A middle-aged neuroscientist walking down Bourbon Street spots a T-shirt that reads, "I don't know, so maybe I'm not." This stimulus zooms from eyes to brain, neuron by neuron, via tiny junctions called synapses. The results? An immediate chuckle and (sometime later) a groundbreaking book titled The Synaptic Self. To Joseph LeDoux, the simple question, "What makes us...
A middle-aged neuroscientist walking down Bourbon Street spots a T-shirt that reads, "I don't know, so maybe I'm not." This stimulus zooms from eyes to brain, neuron by neuron, via tiny junctions called synapses. The results? An immediate chuckle and (sometime later) a groundbreaking book titled The Synaptic Self. To Joseph LeDoux, the simple question, "What makes us who we are?" represents the driving force behind his 20-plus years of research into the cognitive, emotional, and motivational functions of the brain.
LeDoux believes the answer rests in the synapses, key players in the brain's intricately designed communication system. In other words, the pathways by which a person's "hardwired" responses (nature) mesh with his or her unique life experiences (nurture) determine that person's individuality. Here, LeDoux nimbly compresses centuries of philosophy, psychology, and biology into an amazingly clear picture of humanity's journey toward understanding the self.
Equally readable is his comprehensive science lesson, where detailed circuit speak reads like an absorbing--yet often humorous--mystery novel. Skillfully presenting research studies and findings alongside their various implications, LeDoux makes a solid case for accepting a synaptic explanation of existence and provides to the reader generous helpings of knowledge, amusement, and awe along the way. --Liane Thomas --This text refers to an out of print or unavailable edition of this title.
From Publishers Weekly
Despite ongoing debate about the root cause of psychological disorders, most agree that the development of the self is central to the distinction between normality and psychopathology. Yet neuroscientists have been slow to probe the biological basis for our sense of self, focusing instead on states of consciousness. LeDoux (The Emotional Brain), professor at New York University's Center for Neural Sciences, has come up with a theory: it's the neural pathways the synaptic relationships in our brains that make us who we are. Starting with a description of basic neural anatomy (including how neurons communicate, the brain's embryological development and some of the key neural pathways), LeDoux reviews experiments and research, arguing that the brain's synaptic connections provide the biological base for memory, which makes possible the sense of continuity and permanence fundamental to a "normal" conception of self. Writing for a general audience, he succeeds in making his subject accessible to the dedicated nonspecialist. He offers absorbing descriptions of some of the most fascinating case studies in his field, provides insight into the shortcomings of psychopharmacology and suggests new directions for research on the biology of mental illness. While some may disagree with LeDoux's conclusion that "the brain makes the self" through its synapses, he makes an important contribution to the literature on the relationship between these two entities. Agents, Katinka Matson and John Brockman. (On-sale: Jan. 14)
Copyright 2001 Cahners Business Information, Inc.
--This text refers to an out of print or unavailable edition of this title.
......engram to refer to the neural representation of a memory.
It seemed that the memory loss was related more to the size of the lesion than to its placement in the cortex.
He used a behavioral task that could be solved in different ways.
As the lesions got bigger, more processes were distrupted, leaving the animal with fewer options for solving the problem.
H.M could recall many of the events of his earlier life, especially those that occured up to several years before the surgery, he was unable to form memories for experiences that occured after the surgery, hewas unable to form memories for a few seconds (he had short-term memories), but he couldn't convert this information into long-term memories. He failed to recognize himself in a mirror, for example, but did recognize himself from... (查看原文)
关于记忆,最重要的一点: It's a reconstruction of facts and experiences on the basis of the way they were stored, not as they actually occured. 接着从1904年一个德国科学家寻找engram,到Lashley,再到H.M引出的海马,简单的梳理了下对记忆的探索。 ......engram to refer to the neural representation of a memory. It seemed that the memory loss was related more to the size of the lesion than to its place...
2015-02-09 17:162人喜欢
关于记忆,最重要的一点:
It's a reconstruction of facts and experiences on the basis of the way they were stored, not as they actually occured.引自 Adventures in time
......engram to refer to the neural representation of a memory.
It seemed that the memory loss was related more to the size of the lesion than to its placement in the cortex.
He used a behavioral task that could be solved in different ways.
As the lesions got bigger, more processes were distrupted, leaving the animal with fewer options for solving the problem.
H.M could recall many of the events of his earlier life, especially those that occured up to several years before the surgery, he was unable to form memories for experiences that occured after the surgery, hewas unable to form memories for a few seconds (he had short-term memories), but he couldn't convert this information into long-term memories. He failed to recognize himself in a mirror, for example, but did recognize himself from old pictures.
Paul MacLean, the originator of the limbic system concept, conceived of the hippocampus as the seat of the Freudian id, a place in the brain where ideas could be mixed together and confused.引自 Adventures in time
p101.
开始介绍H.M.可以完成的一些任务。
然后关于记忆系统就有了新的认识。
Procedual memory was therefore later renamed with more neutral designation: nondeclaractive memory. The term explicit and implicit memory, suggested by Dan Schacter, essentially refer to the same memory processes as declarative and nondeclarative memory.
Outputs of each of the cortical areas then converge in the rhinal cortical areas, also known as the parahippocampal region, which integrates information from different sensory modalities before shipping it to the hippocampus proper.引自 Adventures in time
接着提到海马与新皮层之间的连接是相互的。
In this way, cortical areas involved in processing a stimulus can, as we will soon see, also participate in the long term storage of memories about that stimulus.
Convergence zones also allow mental representations to go beyond perceptions and to become conceptions - they make possible abstract representation s that are independent of the concrete stimulus.引自 Adventures in time
这种聚合区就像新皮层,在灵长类最多,哺乳动物次之。
接着区分了一下顺行性遗忘和逆行性遗忘。
There are basically two kinds of amnesia: one is an inability to remember things that happenred before the surgery or brain injury (called retrograge amnesia), and the other is an inability to form new memories (called anterograde amnesia). While we' ve focused so far on anterograde amnesia, both forms are present in patient with damage to the temporal lobe. Interestingly, the degree of retrograde amnesia is graded over time - memory is worse for events right before the surgery than for earlier ones.
The graded effect of retrograde amnesia is now believed to occur because the role of hippocampus changes over time - the hippocampus is needed for memory storage initially, butits role decreases as time goes by.引自 Adventures in time
对此有一种基于connectionist modeling的解释。
So-called interleaved learning prevents new information from interfering with old memories.引自 Adventures in time
But with the interleaved learning, where the reoresentaion is built up slowly over many repetitions, the network gradually refines the representation......引自 Adventures in time
p107.
接着关于记忆从海马参与到逐渐皮层独立的可能做了讨论。
Each reinstatement changes cortical synapses a little. Because the reinstatement depend on the hippocampus, damage to the hippocampus affects recent memories, but not old ones that have already been consolidated in the cortex.引自 Adventures in time
接着提到了关于睡眠期间大脑活动的研究。
Subsequently, when the rats went to sleep, the neural patterns seemed to be repeated in the hippocampus, as if the rats were dreaming about the places they had explored.引自 Adventures in time
目前这方面证据还不充分,只是猜想。
然后提到关于新记忆受损比老记忆严重的另外一种可能的解释。
However, with time, the memory trace comes to involve more and more brain regions, especially cortical regions, so that damage to one area, like hippocampus, fails to produce a deficit, since the other areas compensate.
With time, hippocampal activity decreased and came to be unrelated to memory performance, while cortical activity increased and came to be related to the memory performance.引自 Adventures in time
这里提到了图尔文关于记忆的划分。
He argued that episodic memories are about personal experiences (things happened to you at a particular time and place), while semantic memories are about facts (things you come to know, but have not necessarily experienced)......Tulving suggested that episodic memory, which requires conscious recollection of the time and place of some personal experience, is particular characteristic of humans, whereas semantic memories, being the single storage of a fact rather than a personal experience, is within tha capacity of many animals.引自 Adventures in time
One is that episodic memory, while poor, is still present in the children, and that even a littlespisodic memory capacity may be sufficient to support a gooddeal of semantic knowledge......but episodic deficit may be more readily detect.引自 Adventures in time
第二是脑成像没有解剖可靠。
p110.
受到H.M启发,研究者开始在动物身上做实验。
If conscious retrieval was required, the hippocampus tended to be involved.引自 Adventures in time
介绍了Delayed nonmatch to sample,注意是选没出现过的那个。
It turned out, though, that the effects of the lesions were not due to damage to the amygdala or hippocampus, but to damage of surrounding parahippocampal region.引自 Adventures in time
H.M.的这块也受损了。
In sum it seems that the parahippocampal areas and hippocampus make unique contributions, and the delayed nonmatch to sample task reflects the parahippocampal more than the hippocampal contribution.引自 Adventures in time
接着就介绍了去年诺奖获得者的的研究成果,不知道是不是因此得奖的,听新闻上的描述至少也是类似的实验。
......different cells in the hippocampus are active at different locations.
One of the few tasks that hippocampal leision seemed to impair with any consistency was maze learning, a task that is often solved by spatial cues.引自 Adventures in time
然后就介绍了莫里斯水迷宫实验(Morris water maze)。
Damage to the hippocampus in the primates does produce deficits in spatial memory, along with deficit in nonspatial memory.引自 Adventures in time
关于海马还有一种认为其与declarative memory 关系密切。
Specifically, declarative memories are relational. Thus, activation of a declarative memories can be activated independent of the context in which they were established, and by stimuli other than those that were initially involved in the learning.引自 Adventures in time
Conjunction theory则认为海马将各通道的信息混合在一起,成为一个整体了。
In this theory, the original elements, though, are lost, having been formed into conjunctions, while in the relational theory, the elements remain discrete and the hippocampus links them together.引自 Adventures in time
还有一种改进版的configural theory。
The hippocampus learns conjunctions naturally and rapidly. When the hippocampus is damaged, the neocortex can be forced, through extensive training, to also learn conjunctions, but normally it does not do so.引自 Adventures in time
接着开始讲内隐记忆。
The systems that engage in implicit learning are not strictly speaking memory systems. They were designed to perform specific functions......plasticity (the ability to change as a result of experience) is simply a feature of the neuronal infrstructure of these systems that facilitated their operation.
In this sense, explicit memory is, in Stephen Jay Gould's term, an exaptation.引自 Adventures in time
p118.
这里介绍了经典条件反射和操作性条件反射。
The subject is passive involved in classical conditioning (the food comes when the stimulus occurs, regardless of what the subject is doing) but in operant conditioning, the subject responds in a certain way.引自 Adventures in time
The emphasis was on conditoning as a tool for sutdying bahavioral relevant neural changes rather than as a direct model of human memory.引自 Adventures in time
2000年诺奖得主Kandel也是这种研究角度。
接着有一个关于杏仁核的很好的总结。
It had been known that the amygdala plays an important role in fear responses and even learning to fear new stimuli.
The lateral nucleus of the amygdala (lateral amygdala) serves as the input zone. It receives information from the various senses, allowing the outside world to be monitored for threatening information.
When the lateral nucleus detects some threatening stimulus, the central nucleus initiates the expression of defensive behaviors.
The lateral amygdala gets inputs about the stimuli from two sources. It receives a crude but fast representation from subcortical area (the sensory thalamus) and a slower but more complete representation from cortical sensory areas.引自 Adventures in time
这里就是一般的high road 和low road了。
两条通路通向同一神经元。
The inputs reach the neurons...... As a result, the cells are then more capable of charging ahead if the cortical information condirms the threat, or of putting on the brakes if the cortical information establishes that no danger is present.引自 Adventures in time
作者这里还做了特别的提醒:
It should not be assumed that high road is aconscious route to the amygdala...... The amygdala engages in implicit processing, including implicit larning, regardless of which pathway provides it with sensory information. As with any other stimulus, we become consciously aware of an emotional stimulus only when that stimulus is processed by networks involved in something called working memory.引自 Adventures in time
接着讲了lateral nucleus的可塑性。
If an animal is lucky enough to survive one dangerous encounter, its brain should store as much about the experience as possible.引自 Adventures in time
p126.
这里讨论了条件反射所必须的脑区。
It was disovered that removal of entire neocortex had no effect on the ability of rabbits to be conditioned. In fact, eye blink conditioningcould occur following removal of the most forebrain, icluding the amygdala, hippocampus, and other areas.
These researcher showed that leisions of a certain areas of the cerebellum prevented conditioning, and that activity of neurons in thses areas changed during the course of conditioning.引自 Adventures in time
这些实验关注的不是眨不眨眼,而是接受外部刺激以及控制动作。
Control of precise movements at just the right time is a fundamental aspect of mauy of acquired brhavioral skill.引自 Adventures in time
接着开始讲味觉。
An infant will spit out spit bitter foods on the first encouter. Infants born with massive parts of the forebrain missing, and rats with lesions of all of the forebarin and midbrain still exhibit taste preferneces, suggest that taste mediated by the hindbrain.引自 Adventures in time
提到了关于taste aversion的条件反射(CTA)。
The taste path way from the tongue goes to a region of the hindbrain called nucleus of the solitary tract, which is involved in taste preferences. The same general region of the hindbrain receives fibers from the gut, telling the brain about nausea and other gastrointestinal conditions...... The two parts of the nucleus of the solitary tract do project onto a common area in the middle brain called parabrachial nucleus.
Removal of the forebrain, which leaves only the brain stem to run the show, disrupts the acquisition of CTA, in spite of the fact that the same procedure leaves taste prefenrences undisturbed. The parabrachial nucleus thus does not work alone in the mediation of CTA and instead depends on the forebrain areas.引自 Adventures in time
p129.
提了下实验中两种条件反射的联系。
But the first step is that the rat has to learn, through classical conditioning, that the tone predicts the shock.引自 Adventures in time
然后回到了有意识的记忆和无意识的记忆。
Hippocampal damage does not distrupt normal conscious awareness.引自 Adventures in time
The patients with hippocampal damage did not condition in the trace task.引自 Adventures in time
而正常被试当中:
Whether they conditioned was closely related to whether they reported, after the experiment, having noticed a relation between the tone and the puff...... This suggested that the trace conditioning requires awareness, and that the hippocampus mekes this awareness possible.引自 Adventures in time
接着介绍了另外一个实验,在一堆字母L(背景)中找字母T(目标),操作了L的样式。
The normals but not the amnesics benefited from the repetition of the background pattern: they were better at finding the T in the repeated pattern than novel ones......The hippocampus, in other words, was required to process and learn about the unattended background stimuli.引自 Adventures in time
Hippocampus......is able to put together many things at once, to relate or configure them into a context.
The key function of the hippocampus is probably processing relations.引自 Adventures in time
介绍了一下《记忆的七宗罪》这本书。
Even in the face of severe memory problems, its sufferers initially remain much the same person they always were —— they walk and talk the same, and have the same basic habits and traits. As the disease spreads widely to other brain areas, those that function implicitly, personality begins to break down.引自 Adventures in time
Brain development is the major battlefield of nature-nurture conflict. It is less common, but no less appropriate, to think of genes as also influencing us in the form of memory. In this case, though, the synaptic memory comes about as a resultif ancestral rather than personal history. 从胚胎阶段整个发育就有环境因素的参与。 The chemical environment of the embryo is, by necessity, in direct cont...
2015-02-04 11:201人喜欢
Brain development is the major battlefield of nature-nurture conflict.
It is less common, but no less appropriate, to think of genes as also influencing us in the form of memory. In this case, though, the synaptic memory comes about as a resultif ancestral rather than personal history.引自 Building the brain
从胚胎阶段整个发育就有环境因素的参与。
The chemical environment of the embryo is, by necessity, in direct contact with the body chemistry of the mother.
In the neural tube, nonneural precusor cells divide and give rise to neurons.
It's important to make a distinction here between neurogenesis——the birth of new neurons——and synaptogenesis——the creation of new synapses between existing neurons.引自 Building the brain
Segregation is under the direct control of a special set of genes called homeotic genes.
Segregated cells eventually differentiate, which means that they on different shapes and sizes, and end up with different transmitters and modulators.引自 Building the brain
这里发现化学环境对神经元最后的功能影响还是大的,特别是未分化的神经元。
As development proceeds, the neural tube expands and bends, eventually assuming a shape that begins to resemble the brain.引自 Building the brain
这里对于这些神经元的“命运”还是很有争论的。
One possibility is that the function of a cell is specified genetically, so that it is destined to end up in specific areas devoted to a specific function before it leaves the neural tube. Another possibility is that cells learn what to do from the context in which they end up.引自 Building the brain
这里作者依然强调突触比神经元本身对回路功能的贡献更大。
Once neurons reach their destinations, they begin to sprout axons.引自 Building the brain
这里有一些蛋白质作为attractant和repellent引导这个过程。
p72.
We probably don't have enough genes to account for the wiring of each of the brains's trillions of synaptic conncetions.引自 Building the brain
这样就产生了火热的争论:instruction 和 selection。
The exact role of neural activity, though, is heatedly debated, with the main issue of contention being whether activity, especially activity initiated by environmental stimulation, helps creat the mature connections or just selects from the initial set of intrinsically established connections those that will be retained.
Selectionists also assume that there's a good deal of randomness involved.引自 Building the brain
神经元会在发展过程中会死亡目前基本是确定的。
The key issue is not whether synapses are eliminated during development (they clear are) but instead whether the decreases that do occur provide conclusive support for strong version of selectionism - the version that claims that activity only prevents the elimination of synapses.引自 Building the brain
p76.
这里介绍了悲惨的独眼小猫。
Hubel and Wiesel concluded that the development of synapticconnections is a competitive proccess, one in which the connections that are used are kept and those that go unused are elimnated.引自 Building the brain
当然,实际情况比这个复杂。
They found that as development proceeded, mauy axons did indeed retract (consistent with a selectionist view), but that the remaining axons also increased in complexity (consistent with an instructional view).引自 Building the brain
It is probably best to think of instruction and selection as two complementary meas by which circuits can be constructed rather than as mutually exclusive theories of brain development.引自 Building the brain
It has taken tremendous amount of work to demonstrate that activity both instructs the formation of new connections and selects used ones from a preexisting pool.引自 Building the brain
p79.
赫布大神出场
In 1949, Donald Hebb, a Canadian psychologist, proposed that if two neurons are active ar the same time, and one is presynaptic to the other, then the connection between them will be strengthened.引自 Building the brain
这一章讲的比较简单,书的接下来还有大量篇幅涉及具体的机制。
Hebbian plasticity involves the released tranmitter to two kinds of postsynaptic receptors. One of these receptors records that the post cell was active, and the other records which presynaptic terminals contracting the postsynaptic cell were active at the same time.
NMDA receptors, appear to be particular important in that they are able to detect the match between activity in the presynaptic and post synaptic neuron.
Another important set of molecules are neurotrophins, special tonic that promote the survival and growth of neurons.引自 Building the brain
这种物质是从postsynaptic cell释放然后被presynaptic cell吸收的。
Cell death is prevented if a presynaptic terminal receives a life-sustaining shot of neurotrophins from postsynaptic partner.
The surviving terminals (those that were active) also begin to spout new connections.引自 Building the brain
p82.
开始讨论“先天”。
One is the
idea that genes make us all the same, giving us trait that we share with other members of our species. The other is that genes make us unique.引自 Building the brain
第一种取向介绍了动物行为学。
The classic method used by ethologists to test innateness was to show that a behavior was present at birth or shortly thereafter, or, mre generally, that it merged in the absence of an opportunity for the organism to have learned from environmental stimulation.引自 Building the brain
接着介绍了对于反驳行为主义的几个经典证据,让你恶心的东西更容易和食物建立联系。
The language may be innate is supported by studies of pidgin language, a simple, crude form of verbal communication among people who speak different languages but live together and have to communicate with one another. Pidgin lacks grammer when it is initially pieced together, but by the second generation, it begins to take on a grammatical structure.
It has been proposed that humans have innate knowledge about numbers, physics, and even about how other human mind work.引自 Building the brain
之后又提了下对于进化心理学的反驳。
其中比较重要的一个反驳是:
As Gould's exaptation argument points out, something can be innate (passed on genetically) even if the role it plays today is not the one form which it evolved.引自 Building the brain
Constructivists accept the principle that genes build the overall structure, and the regressive events like synaptic selection take place, but they argue that epigenetic prewiring and selection alone cannot explain cognition.引自 Building the brain
Together, these findings lead to the conclusion that genes help in the explanation of the behavioral difference between group but not within groups, at least in this case.
Genes may play a role in placing a function in the brain of every human, and at the same time make a relatively small contribution to differences in the way that function is wired in individuals.引自 Building the brain
An seldom is any brain function as complex as those involved in behavioral or mental process under the control of one gene.引自 Building the brain
接着介绍了关键期,敏感期对学习的影响。
Language learning is more flexible in children than in adults, as anyone who has tried to learn a second language after puberty knows.
Whether math or music learning has acritical period of synaptic development is not known.引自 Building the brain
这里有一个很有趣的观点:
the early years are crucial not because the window of opportunity closes but because what is learned at this time becomes the foundation of subsequent learning.引自 Building the brain
Following the cognitive revolution, though, motivations, like emotions, were overlooked by many psychologists and brain scientists. Whether all motivated actions are necessarily based on emotional activity is debatable. But that emotions are powerful motivation. 然后从Hull的驱力理论(drive theory)讲起。 That is, what we do today in a certain situation is function of what we did in the past wha...
2015-04-14 11:17
Following the cognitive revolution, though, motivations, like emotions, were overlooked by many psychologists and brain scientists.
Whether all motivated actions are necessarily based on emotional activity is debatable. But that emotions are powerful motivation.引自 THE LOST WORLD
然后从Hull的驱力理论(drive theory)讲起。
That is, what we do today in a certain situation is function of what we did in the past what was successful in reducing drives in similar way.引自 THE LOST WORLD
这里再次提到了两种条件反射的区别。
Instrumental conditioning contrasts with Pavlovian or classical conditioning, where the rewarding or punishing stimulus occurs regardless of what the animal does.引自 THE LOST WORLD
从某些驱力理论解释不了的现象有引出了诱因理论(incentive theory)。
I believe that all we need to acceot is that in the presence of conditioned (learned) or unconditioned (innate) incentives, emotion systems are activated, placing the brain in a state where an instrumental response becomes a highly probable outcome.引自 THE LOST WORLD
把实验分为两个阶段,第一个阶段形成的反应,在第二个阶段也能保持。
The shock, by the way, was never presented in the new chamber. The tone had become a negative secondary incentive, and behaviours that eliminated this simuluswere reinforced and learned as a habit.引自 THE LOST WORLD
用恐惧的好处是作者对杏仁核很熟,通过人工损毁发现了分离。
Damage to the lateral nucleus prevented the learning of the escape response, but central nucleus leision had no effect.
...... the central nucleus was found to be involved in fear reaction but not fear action, and the basal nucleus in the fear action but not reaction.引自 THE LOST WORLD
p244.
开始讲快乐中枢的发现(pleasure center)。
The reason these sites were so effective wa not because the hypothalamus is the reward center of the brain, but because a major nerve pathway passes through the hypothalamus.引自 THE LOST WORLD
从这个实验来看。
This is a motivational version of my notion that emotional beahaviors are not necessarily caused by emotional feelings.引自 THE LOST WORLD
Although there are rewarding conditions that do not depend on dopamine , much of what we know about rewards centers around the role of dopamine.引自 THE LOST WORLD
通过阻断多巴胺。
......the animals still "like" the reward when they consuming it, but they are no longer motivated to work for it. Dopamie is thus more involved in anticipatory behaviors (looking for food or drink or a sexual partner) than in cosummatory responses (eating, drinking, having sex).引自 THE LOST WORLD
接着提到了伏隔核。
......the nucleus accumbens, a region of sriatum located in front of the amygdala near the bottom of the forebrain.
...... nucleus accumbens sits ar the crossroads of emotion and movement, and that dopamine release in this region plays crucial role in motivated or goal directed behavior.引自 THE LOST WORLD
Once an emotional habit is well learned, the brain systems involved in expressing it become simpler. The amygdala, for example, drops out of the circuit...... The accumbens likewise drops out once the response is learned.......引自 THE LOST WORLD
p252.
开始提到情绪在行为选择中的作用。
达马西奥的研究是必须出现的。
He and his collegues have shown that patient with damage to the orbital prefrontal region have poor judgement and often make decisions that lead to socially in appropriate courses of action....... to use emotional information to guide action.引自 THE LOST WORLD
在实验室中一般倾向如去定位特定的区域和功能。
......in more natural setting, where decisions involve the integration of cognitive and emotional information, it is likely that interaction rather than dissociations between the areas will be commonplace.引自 THE LOST WORLD
介绍了一些早期的神经元与记忆的关系猜想,重点是赫布。 When an axon of cell A is near enough to excite cell B or repeatedly and consistently takes part firing it, some growth process or metabolic changes take place in one or both cells such that A's efficiency, as one of the cells firing B is increased. 两个刺激之间能有联系,则 This means that there has to be some neuron (or a set of neurons) tha...
2015-02-14 09:03
介绍了一些早期的神经元与记忆的关系猜想,重点是赫布。
When an axon of cell A is near enough to excite cell B or repeatedly and consistently takes part firing it, some growth process or metabolic changes take place in one or both cells such that A's efficiency, as one of the cells firing B is increased.引自 Small change
两个刺激之间能有联系,则
This means that there has to be some neuron (or a set of neurons) that receives information about both stimuli.引自 Small change
接着就介绍了一些早期的研究。
Repetitive stimulation of nerves going to the spinal cord led to an increase in size of the electrical response elicited in post synaptic nrurons in the spinal cord.引自 Small change
但是这种情况维持的时间很短。
又介绍了一个关于猫的habituation的实验。
Habituation is a form of learning in which repeated presentation of a stimulus leads to a weakening of response.
Thompson and Spencer ruled out changes in the ability of the input and output nerves to transmit signals, and concluded that the plastic changes must have crucially involved the interneurons.引自 Small change
He noticed that a brief burst of electrical stimuli delivered ot fibers headed for the hippocampus in the rabbit led to a dramatic and long-lasting increase in transmission at synapse in the hippocampus.引自 Small change
这个就是长时程增强(LTP)。
The key finding was that, following the potentiating pulses, the synaptic response got bigger, relative to the baseline response, and remained bigger for hours.引自 Small change
Rapid acquisition, persistence, specificity, and associativity are all features one would expect of a memory mechanism.
Giving potentiating inputs to one pathway, therefore, does not automatically change all of the synapses on the postsynaptic neurons; it only changes those synapses that were stimulated.引自 Small change
两条通路。
When each was stimulated in succession with weak stimuli, no LTP resulted. But if the two pathways were stimulated simultaneously with the weak stimuli, the stimuli could combine (cooperate) to produce LTP in both pathways.引自 Small change
这里有一副比较简单易懂的长时程增强的图。
后来通过人工激活突触后神经元,
When a weak presynaptic input arrived during this induced activity, synapses over which it was transmitted to the postsynaptic cell was strengtherned.引自 Small change
p144.
这里介绍了glutamate receptor和钙离子对LTP的影响。
The two findings actually complement each other, since it is the special glutamate receptor that allows calcium to rise in the postsynaptic cell when an action potential occurs.引自 Small change
这里简单提了下AMPA和NMDA受体。
Once glutamate has activated the postsynaptic cell (caused it to fire an action potential) by binding to AMPA receptors, the block on the NMDA receptors is removed, and glutamate can open the receptor channel and allow calcium to enter the cell. LTP is the result.
For NMDA receptors to pass calcium, both presynaptic and postsynaptic cell must be active. This is the basic requirement for Hebbian plasticity.
The rise in calium inside the post synaptic cell then leads to the activation of kinases that travel to the cell nucleus where addttional molecular processes occur, including gene activation, which in turn lads to the synthesis of new protein that contribute to the strengthing the synapses.
When synaptic activity in the strong pathway activated the postsynaptic cell, the block on NMDA receptors will be removed, even at weak synapses.
NMDA receptors ...... they are able to register that presynaptic and postsynaptic neurons were active at the same time.引自 Small change
It has been known for several decades that if animals are given drugs that prevent the brain from making new proteins, they are able to learn normally but are unable to form long-lasting memories.引自 Small change
这里有个定义,第二信使:
Their job is to initiate chemical recation within the cell on the basis of information provided from outsaide the cell during neurotransmission by first messengers.引自 Small change
这里介绍了启动kinases 对于AMPA受体的作用。
As a result, after the induction of LTP, the same amount of glutamate released from the presynaptic cell by an action potential will have more AMPA receptors to bind to.引自 Small change
关于突触前神经元在这个过程中是否发生改变目前还有争议。
One possible way this could happen is by the means of retrograde messengers, substances released by the postsynaptic cell after LTP is induced and taken up by the presynaptic terminal, which cause changes in the case of glutamate release here.引自 Small change
When the new proteins are subsequently made in the cell body, they are then shipped out to essentially all possible synapses in the cell, but only synapses that were tagged during the initial stimulation are able to use the new proteins to stabilized the connection with the presynaptic terminal.
Weak HFS leads to a short-lasting form of LTP (early LTP) that does not require gene expression and protein synthesis. However, it does creat the tag.引自 Small change
除了树突自己的变化。
The other part of the explanation is related to the actual growth of new synapses.
Recent studies demonstrate that proteins can be synthesized in denderites.引自 Small change
再接着介绍了阻断NMDA受体的小鼠进行水迷宫实验的情况。
Particular difficult to ascertain has been the issue of whether NMDA blockade produces a specific effect on learning itself, or instead changes other less specific capacities, such as the ability to preceive a given stimulus or the ability of desire to perform the appropriate response.引自 Small change
In some studies, hippocampal-dependent learning is unaffected by treatments that block LTP. This type of result, though, has been fairly rare, and centainly is not compelling enough to undermine the whole field. Futher, we now know that there are variety of different forms of LTP, some involving NMDA receptors and some not......引自 Small change
这里说了这么多,但都没有直接证明外显的学习与LTP的关系。
Rogan instead started with a circuit known to be involved in fear conditioning and then asked whether LTP occured in that circuit. The reversal of the strategy (starting with a learning circuit and looking for plasticity in it, rather then starting with a form of plasticiy and asking how it might related to learning) turned out to be very advantageous.引自 Small change
他用声音做条件刺激,电击做无条件刺激。在成功配对后,单独呈现声音也在杏仁核的相关区域引起LTP。
Indeed, Rogan's results showed that fear conditioning and LTP induction produced very similar changes in the electrical responses of amygdala cells to sound stimuli.
In spatial learning, a rat is free to learn about any of the may stimuli present in the environment, making it difficult to determine, in Hebbian terms, precisely what's being asspciated with what. INcontrast, fear conditioning is a straightforward form of associative learning that is easy to define in terms of Hebbian plasticity, where strong (foot shock) and weak (sound) stimuli interact at synapses on the same cells.
......disruption in the lateral amygdala of protein syntheisis or of some of the same kinases that prevent the induction of late LTP in the hipppcampus interferes with the formation of long-term memory for fear conditioning without affecting short-term memory.
Fear conditioning and lateral amygdala LTP thus seem to require the same mix of molecules that has been implicited in synaptic plasiticy and memory in the hippocampus.引自 Small change
最后总结了下这些研究更广泛的意义,以及一些未解决的问题。
Also unsolved is the locus of memory storage - plasticity in the lateral amygdala is clearly involved, but whether this is the only site of change that is maitiained over time remains to be determined.引自 Small change
接着介绍了一种消除创伤后记忆的可能办法,穿越虫洞上也提到过。
That is, if you take a memory out of storage you have to make new proteins (you have to store, or reconsolidate it) in order for the memory to remain a memory.引自 Small change
p162.
用无脊椎动物中海兔属的的实验来当做例子,介绍这个领域的研究。
The gill withdrawal reflex exhibits several forms of learning, including habituation: the gill retracts less if the mantle is touched repeatedly...... Habituation can reversed rapidly by giving a strong stimulus, such as an electric shock, to some other part of the mollusk's body, like the tail. Touch of the mantle after a shock results in a big response. This is an independent form of nonassociative learning called sensitization.
Associative learning - namely, classical defense or fear conditioning - also occurs in the gill withdrawal reflex.
Conditioning and sensitzation are similar in that a strong stimulus changes the response to a weak one. But they differ in specificity: in associative conditioning, the amplified response only occurs in the reaction to a stimulus that was paired with the shock, whereas in sensitization the response to stimuli that have no relation to the shock is bigger.引自 Small change
The serotonin binds to serotonin receptors located on the presynaptic axon terminal, and leads to the activation of protein kinase A (PKA), whichi results in a greater amount of glutamate release and thus a bigger postsynaptic response.
Because the increase in the efficiency of transmission between the sensory and motor neuron is due entirely to alteration in the sensory seuron terminal, it is refered to as presynaptic facilitation. Because the state of the activity of the postsynaptic neuron is irrelevant sensitization by dedinition is a form of non-Hebbian plasticity.
The two effects (persistent of PKA and formation of new connections) combine to produce long-lasting increase in transmission between the sensory and motor neurons, and stronger reflex responses.引自 Small change
One way of understanding this is that nonassociative (non-Hebbian) presynaptic facilitation functions as the presynaptic component of associative (Hebbian) plasticity.
Also the possibility that fear conditioning, amygdala LTP, and several forms of hippocampal plasticity might, like plasticity in Aplysia, involve presynaptic as well as postsynaptic changes futher strengthens the notion similar mechanisms are used to make memories in diverse species.引自 Small change
最后讲了变种果蝇的研究。
When given the choice between going into a chamber that contained an odor associated with the shock and a chamber that held a different oder, the flies oftern avoided the former chamber.
It is important to keep in mind that a mutant animal goes through its entire life with the genetic alteration, sometimes making it difficult to distinguish effects on learning and memory from other more general consequences of having grown up without certain proteins and their and products.
In each of this mutants, learning actually did take place to come extent, but then decayed rapidly after training.引自 Small change
通过集中学习和分散学习间的差距来测量记忆的效果。
......increase the level of gene transcription factor CREB available in flies at the time just before training...... with extra CREB, a single training trail could accomplish what required multiple trails in normal flies - creat a memory that lasts for days.引自 Small change
p2. My notion of personality is pretty simple: it's that your "self," the essence of who you are reflects patterns of interconnectivity between neurons in your brain. 其他人可能会认为对自我的描述还应该包含心理,社会,道德,美学和精神的方面。 作者提出以下回应: My theory......It is rather, an attempt to portray the way the psychological, social, moral, aesthetic, or spirtual self is realized. 接...
2015-01-17 10:18
p2.
My notion of personality is pretty simple: it's that your "self," the essence of who you are reflects patterns of interconnectivity between neurons in your brain.引自 The big one
其他人可能会认为对自我的描述还应该包含心理,社会,道德,美学和精神的方面。
作者提出以下回应:
My theory......It is rather, an attempt to portray the way the psychological, social, moral, aesthetic, or spirtual self is realized. 引自 The big one
接着大概的讨论了下先天和后天的关系。
引用了同卵双胞胎间的差异和实验室里没见过猫的耗子。
带了下freeze——fight or flight的第一步可能的作用。
然后就引出了杏仁核(amygdala)及其大概的作用。
杏仁核的通路也是新经验表达恐惧的通路:
The brain can, as a result, deal with novel dangers by taking advantage of evoliutionarily fine-tuned ways of responding.引自 The big one
learning is not a function that those system originally were designed to perform.
Learning (synaptic plasticity) is just a feature that help them do their better job.引自 The big one
The question Synaptic Self asks is not "How does consciousness come out of the brain?" but rather "How does our brain make us who we are?"引自 The big one
作者这里也提到了无意识,但他特别说明了一下。
what I mean by this term is the many things that the brain does that are not available to consciousness.引自 The big one
相对于无意识,意识是最近才出现的。
在最后提到了两本题材相关的书籍,只是关注点不同。
《The feeling of what happens》
《The mind's past》
后记:第一次读这本书是两年以前了,中途读读停停,这次重读,收获还是很多的。
一开始就引用了詹姆斯的, a man's self is the sum total of all that he can call his...... 接着接介绍了一个由梵蒂冈赞助的高端会议,主题是: God to influence people's lives without violating the law of physics. 简单的扯了下如何解释上帝和我们的世界的关系。 My reason for discussing this conference and issues it raised is not so much to argue the point that it would be difficult, and maybe impossible...
2015-01-20 15:04
一开始就引用了詹姆斯的,
a man's self is the sum total of all that he can call his......引自 Seeking the self
接着接介绍了一个由梵蒂冈赞助的高端会议,主题是:
God to influence people's lives without violating the law of physics.引自 Seeking the self
简单的扯了下如何解释上帝和我们的世界的关系。
My reason for discussing this conference and issues it raised is not so much to argue the point that it would be difficult, and maybe impossible, to find scientific solutions to theological riddles, but rather to demonstrate that a spiritual view of the self isn't (or doesn't have to be) completely incompatible with biological one.引自 Seeking the self
接着转向哲学对这个问题的讨论。
几句带过了希腊时代。
重点讲了下笛卡尔,
His solution was to propose that "the mental" and "the physical" were separate substances that met and interacted at a place in the brain.引自 Seeking the self
The extent to which other animals have any kind of consciousness is, unfortunately, impossibe to know.
Philosophy will probably not give us the kind of foundationwe need to pursue the relation between and the brain.引自 Seeking the self
p22.
大致梳理了下各个心理学派对意识的观点。
其中行为主义和认知的这部分引用的比较好:
Some of its adherents were methodological brhaviorists, which meant they didn't necessarily reject the existence of consciousness, but simply believed it couldn't be studied. Radical behaviorists, in contrast, actually denied that consciousness existed. For them, mental states were illusions created by tendencies to act in one way or another.
Cognitive scientists, however, were studying mental process rather than the content of consciousness.
But we are not usually aware of the process that were involved in generating that content.
The fact that cognitive processes are not dependent on consciousness (actually consciousness depends on unconscious cognitive processed).引自 Seeking the self
But because many are at least partly correct......synthesize across them.
From here on, when I use the term the self I am referring to the totality of the living organism.引自 Seeking the self
The self is the totality of what an organism in physically, biologically, psychologically, socially and culturally.
It includes......things that others know about us that what we do not realize.引自 Seeking the self
一开始介绍了几个大众文化对于脑的曲解或误读:只用10%,各种功能分别位于特定的脑区,激素、神经递质满脑子跑决定我们的心智状态。 前两点比较基础,第三种看起来很有理, chemicals are also impartant, but mainly because of their work at synapses within founctional system. 接着大概讲了下前脑,中脑,后脑的划分和跨物种的比较。 接着讲了下新皮层, the wrinkled outer layer, the neocortex. Researchs were able ...
chemicals are also impartant, but mainly because of their work at synapses within founctional system.引自 The most unaccountable of machinery
接着大概讲了下前脑,中脑,后脑的划分和跨物种的比较。
接着讲了下新皮层,
the wrinkled outer layer, the neocortex.
Researchs were able to use this information to find the equivalent (or at least the semblance) of a neocortex in both birds and reptiles, suggesting both that is wasn't so new after all and that it certainly wasn't unique to mammals.引自 The most unaccountable of machinery
interactions between neurons across contact barries make possible memory, consciousness and other facets of mind.引自 The most unaccountable of machinery
佛洛依德的contact barriers没造成很大影响,后来谢灵顿提出的突触成为目前的教材标配。
By knowing the function performed by a few cells of most organs in the body, whether the liver, kidney, or gall bladder, you can deduce the organ's overall function.引自 The most unaccountable of machinery
接着就介绍了神经元的结构,特别强调一下:
many dendrites have little knobs called spined extending from them.
Spines are often where axons from other neurons terminate and form synapses.引自 The most unaccountable of machinery
The electrical change produced in the dendrite has to be propagated to the cell body, and then to axon.
Action potential is generated in the initial part of the axon where it connects with the cell body.引自 The most unaccountable of machinery
If you were to place a microphone in the chandelier at the center of the room high above the crowd, you probably wouldn't be able to make out what was being said, for the many unrelated conversations would blend together in the microphone.
A circuit is agroup of neurons that are linked together by synaptic connections. A system is a complex circuit that performs some specific function, like seeing or hearing, or dectecting and responding to danger.引自 The most unaccountable of machinery
分别介绍了下:projection neurons, interneurons。
Interneurons, also called local circuit cells, send their short axons to nearby neurons, oftern projection neurons, and are involved in information processing within a given level of a hierarchical circuit.引自 The most unaccountable of machinery
以及三种简单的回路模式:hierarchical circuit, local circuit, single source divergent circuit。
The balance between excitatory and inhibitory inputs to a neuron determines whether it will fire.引自 The most unaccountable of machinery
Whether the postsynaptic cell fire depends not only on the counterbalancing force of GABA inhibition, but also on other chemicals that are present at the time. These are called modulators.引自 The most unaccountable of machinery
They can affect dramatically the ability of a cell to be fired by other inputs, but cannot do so with precise timing.
Monoamines produce global state changes in many brain areas simultaneously.引自 The most unaccountable of machinery
这里还提了下特别提了下血清素的作用。
HORMONES:
Because hormones reach the brain though the blood stream, they can influence many regions simultaneously. However, since only certain circuit in those areas, posses the relevant receptors, considerable specificity can be achieved by hormonal modulation.引自 The most unaccountable of machinery
In order for two neurons to communicate electrically, their membranes have to fuse in such a way as to allow the dircet flow of electricity from one to the other. These point of fusion are called gap junction.
Our abilities to see, hear, remember, fear danger, and desire happiness all involve excitatory (glutamate) synaptic transmission regulated by inhibitory (GABA) synapses and modulated by peptides, amines, and hormones.引自 The most unaccountable of machinery
Valium, which works by facilitating GABA transmission.
Drugs like Prozac work by increasing the amount of serotonin available at synapses.引自 The most unaccountable of machinery
Because psychological and behavioral functions are mediated by aggregates of cells joined by synapses and working together rather than by individual neurons in isolation.引自 The most unaccountable of machinery
Brain development is the major battlefield of nature-nurture conflict. It is less common, but no less appropriate, to think of genes as also influencing us in the form of memory. In this case, though, the synaptic memory comes about as a resultif ancestral rather than personal history. 从胚胎阶段整个发育就有环境因素的参与。 The chemical environment of the embryo is, by necessity, in direct cont...
2015-02-04 11:201人喜欢
Brain development is the major battlefield of nature-nurture conflict.
It is less common, but no less appropriate, to think of genes as also influencing us in the form of memory. In this case, though, the synaptic memory comes about as a resultif ancestral rather than personal history.引自 Building the brain
从胚胎阶段整个发育就有环境因素的参与。
The chemical environment of the embryo is, by necessity, in direct contact with the body chemistry of the mother.
In the neural tube, nonneural precusor cells divide and give rise to neurons.
It's important to make a distinction here between neurogenesis——the birth of new neurons——and synaptogenesis——the creation of new synapses between existing neurons.引自 Building the brain
Segregation is under the direct control of a special set of genes called homeotic genes.
Segregated cells eventually differentiate, which means that they on different shapes and sizes, and end up with different transmitters and modulators.引自 Building the brain
这里发现化学环境对神经元最后的功能影响还是大的,特别是未分化的神经元。
As development proceeds, the neural tube expands and bends, eventually assuming a shape that begins to resemble the brain.引自 Building the brain
这里对于这些神经元的“命运”还是很有争论的。
One possibility is that the function of a cell is specified genetically, so that it is destined to end up in specific areas devoted to a specific function before it leaves the neural tube. Another possibility is that cells learn what to do from the context in which they end up.引自 Building the brain
这里作者依然强调突触比神经元本身对回路功能的贡献更大。
Once neurons reach their destinations, they begin to sprout axons.引自 Building the brain
这里有一些蛋白质作为attractant和repellent引导这个过程。
p72.
We probably don't have enough genes to account for the wiring of each of the brains's trillions of synaptic conncetions.引自 Building the brain
这样就产生了火热的争论:instruction 和 selection。
The exact role of neural activity, though, is heatedly debated, with the main issue of contention being whether activity, especially activity initiated by environmental stimulation, helps creat the mature connections or just selects from the initial set of intrinsically established connections those that will be retained.
Selectionists also assume that there's a good deal of randomness involved.引自 Building the brain
神经元会在发展过程中会死亡目前基本是确定的。
The key issue is not whether synapses are eliminated during development (they clear are) but instead whether the decreases that do occur provide conclusive support for strong version of selectionism - the version that claims that activity only prevents the elimination of synapses.引自 Building the brain
p76.
这里介绍了悲惨的独眼小猫。
Hubel and Wiesel concluded that the development of synapticconnections is a competitive proccess, one in which the connections that are used are kept and those that go unused are elimnated.引自 Building the brain
当然,实际情况比这个复杂。
They found that as development proceeded, mauy axons did indeed retract (consistent with a selectionist view), but that the remaining axons also increased in complexity (consistent with an instructional view).引自 Building the brain
It is probably best to think of instruction and selection as two complementary meas by which circuits can be constructed rather than as mutually exclusive theories of brain development.引自 Building the brain
It has taken tremendous amount of work to demonstrate that activity both instructs the formation of new connections and selects used ones from a preexisting pool.引自 Building the brain
p79.
赫布大神出场
In 1949, Donald Hebb, a Canadian psychologist, proposed that if two neurons are active ar the same time, and one is presynaptic to the other, then the connection between them will be strengthened.引自 Building the brain
这一章讲的比较简单,书的接下来还有大量篇幅涉及具体的机制。
Hebbian plasticity involves the released tranmitter to two kinds of postsynaptic receptors. One of these receptors records that the post cell was active, and the other records which presynaptic terminals contracting the postsynaptic cell were active at the same time.
NMDA receptors, appear to be particular important in that they are able to detect the match between activity in the presynaptic and post synaptic neuron.
Another important set of molecules are neurotrophins, special tonic that promote the survival and growth of neurons.引自 Building the brain
这种物质是从postsynaptic cell释放然后被presynaptic cell吸收的。
Cell death is prevented if a presynaptic terminal receives a life-sustaining shot of neurotrophins from postsynaptic partner.
The surviving terminals (those that were active) also begin to spout new connections.引自 Building the brain
p82.
开始讨论“先天”。
One is the
idea that genes make us all the same, giving us trait that we share with other members of our species. The other is that genes make us unique.引自 Building the brain
第一种取向介绍了动物行为学。
The classic method used by ethologists to test innateness was to show that a behavior was present at birth or shortly thereafter, or, mre generally, that it merged in the absence of an opportunity for the organism to have learned from environmental stimulation.引自 Building the brain
接着介绍了对于反驳行为主义的几个经典证据,让你恶心的东西更容易和食物建立联系。
The language may be innate is supported by studies of pidgin language, a simple, crude form of verbal communication among people who speak different languages but live together and have to communicate with one another. Pidgin lacks grammer when it is initially pieced together, but by the second generation, it begins to take on a grammatical structure.
It has been proposed that humans have innate knowledge about numbers, physics, and even about how other human mind work.引自 Building the brain
之后又提了下对于进化心理学的反驳。
其中比较重要的一个反驳是:
As Gould's exaptation argument points out, something can be innate (passed on genetically) even if the role it plays today is not the one form which it evolved.引自 Building the brain
Constructivists accept the principle that genes build the overall structure, and the regressive events like synaptic selection take place, but they argue that epigenetic prewiring and selection alone cannot explain cognition.引自 Building the brain
Together, these findings lead to the conclusion that genes help in the explanation of the behavioral difference between group but not within groups, at least in this case.
Genes may play a role in placing a function in the brain of every human, and at the same time make a relatively small contribution to differences in the way that function is wired in individuals.引自 Building the brain
An seldom is any brain function as complex as those involved in behavioral or mental process under the control of one gene.引自 Building the brain
接着介绍了关键期,敏感期对学习的影响。
Language learning is more flexible in children than in adults, as anyone who has tried to learn a second language after puberty knows.
Whether math or music learning has acritical period of synaptic development is not known.引自 Building the brain
这里有一个很有趣的观点:
the early years are crucial not because the window of opportunity closes but because what is learned at this time becomes the foundation of subsequent learning.引自 Building the brain
Following the cognitive revolution, though, motivations, like emotions, were overlooked by many psychologists and brain scientists. Whether all motivated actions are necessarily based on emotional activity is debatable. But that emotions are powerful motivation. 然后从Hull的驱力理论(drive theory)讲起。 That is, what we do today in a certain situation is function of what we did in the past wha...
2015-04-14 11:17
Following the cognitive revolution, though, motivations, like emotions, were overlooked by many psychologists and brain scientists.
Whether all motivated actions are necessarily based on emotional activity is debatable. But that emotions are powerful motivation.引自 THE LOST WORLD
然后从Hull的驱力理论(drive theory)讲起。
That is, what we do today in a certain situation is function of what we did in the past what was successful in reducing drives in similar way.引自 THE LOST WORLD
这里再次提到了两种条件反射的区别。
Instrumental conditioning contrasts with Pavlovian or classical conditioning, where the rewarding or punishing stimulus occurs regardless of what the animal does.引自 THE LOST WORLD
从某些驱力理论解释不了的现象有引出了诱因理论(incentive theory)。
I believe that all we need to acceot is that in the presence of conditioned (learned) or unconditioned (innate) incentives, emotion systems are activated, placing the brain in a state where an instrumental response becomes a highly probable outcome.引自 THE LOST WORLD
把实验分为两个阶段,第一个阶段形成的反应,在第二个阶段也能保持。
The shock, by the way, was never presented in the new chamber. The tone had become a negative secondary incentive, and behaviours that eliminated this simuluswere reinforced and learned as a habit.引自 THE LOST WORLD
用恐惧的好处是作者对杏仁核很熟,通过人工损毁发现了分离。
Damage to the lateral nucleus prevented the learning of the escape response, but central nucleus leision had no effect.
...... the central nucleus was found to be involved in fear reaction but not fear action, and the basal nucleus in the fear action but not reaction.引自 THE LOST WORLD
p244.
开始讲快乐中枢的发现(pleasure center)。
The reason these sites were so effective wa not because the hypothalamus is the reward center of the brain, but because a major nerve pathway passes through the hypothalamus.引自 THE LOST WORLD
从这个实验来看。
This is a motivational version of my notion that emotional beahaviors are not necessarily caused by emotional feelings.引自 THE LOST WORLD
Although there are rewarding conditions that do not depend on dopamine , much of what we know about rewards centers around the role of dopamine.引自 THE LOST WORLD
通过阻断多巴胺。
......the animals still "like" the reward when they consuming it, but they are no longer motivated to work for it. Dopamie is thus more involved in anticipatory behaviors (looking for food or drink or a sexual partner) than in cosummatory responses (eating, drinking, having sex).引自 THE LOST WORLD
接着提到了伏隔核。
......the nucleus accumbens, a region of sriatum located in front of the amygdala near the bottom of the forebrain.
...... nucleus accumbens sits ar the crossroads of emotion and movement, and that dopamine release in this region plays crucial role in motivated or goal directed behavior.引自 THE LOST WORLD
Once an emotional habit is well learned, the brain systems involved in expressing it become simpler. The amygdala, for example, drops out of the circuit...... The accumbens likewise drops out once the response is learned.......引自 THE LOST WORLD
p252.
开始提到情绪在行为选择中的作用。
达马西奥的研究是必须出现的。
He and his collegues have shown that patient with damage to the orbital prefrontal region have poor judgement and often make decisions that lead to socially in appropriate courses of action....... to use emotional information to guide action.引自 THE LOST WORLD
在实验室中一般倾向如去定位特定的区域和功能。
......in more natural setting, where decisions involve the integration of cognitive and emotional information, it is likely that interaction rather than dissociations between the areas will be commonplace.引自 THE LOST WORLD
介绍了一些早期的神经元与记忆的关系猜想,重点是赫布。 When an axon of cell A is near enough to excite cell B or repeatedly and consistently takes part firing it, some growth process or metabolic changes take place in one or both cells such that A's efficiency, as one of the cells firing B is increased. 两个刺激之间能有联系,则 This means that there has to be some neuron (or a set of neurons) tha...
2015-02-14 09:03
介绍了一些早期的神经元与记忆的关系猜想,重点是赫布。
When an axon of cell A is near enough to excite cell B or repeatedly and consistently takes part firing it, some growth process or metabolic changes take place in one or both cells such that A's efficiency, as one of the cells firing B is increased.引自 Small change
两个刺激之间能有联系,则
This means that there has to be some neuron (or a set of neurons) that receives information about both stimuli.引自 Small change
接着就介绍了一些早期的研究。
Repetitive stimulation of nerves going to the spinal cord led to an increase in size of the electrical response elicited in post synaptic nrurons in the spinal cord.引自 Small change
但是这种情况维持的时间很短。
又介绍了一个关于猫的habituation的实验。
Habituation is a form of learning in which repeated presentation of a stimulus leads to a weakening of response.
Thompson and Spencer ruled out changes in the ability of the input and output nerves to transmit signals, and concluded that the plastic changes must have crucially involved the interneurons.引自 Small change
He noticed that a brief burst of electrical stimuli delivered ot fibers headed for the hippocampus in the rabbit led to a dramatic and long-lasting increase in transmission at synapse in the hippocampus.引自 Small change
这个就是长时程增强(LTP)。
The key finding was that, following the potentiating pulses, the synaptic response got bigger, relative to the baseline response, and remained bigger for hours.引自 Small change
Rapid acquisition, persistence, specificity, and associativity are all features one would expect of a memory mechanism.
Giving potentiating inputs to one pathway, therefore, does not automatically change all of the synapses on the postsynaptic neurons; it only changes those synapses that were stimulated.引自 Small change
两条通路。
When each was stimulated in succession with weak stimuli, no LTP resulted. But if the two pathways were stimulated simultaneously with the weak stimuli, the stimuli could combine (cooperate) to produce LTP in both pathways.引自 Small change
这里有一副比较简单易懂的长时程增强的图。
后来通过人工激活突触后神经元,
When a weak presynaptic input arrived during this induced activity, synapses over which it was transmitted to the postsynaptic cell was strengtherned.引自 Small change
p144.
这里介绍了glutamate receptor和钙离子对LTP的影响。
The two findings actually complement each other, since it is the special glutamate receptor that allows calcium to rise in the postsynaptic cell when an action potential occurs.引自 Small change
这里简单提了下AMPA和NMDA受体。
Once glutamate has activated the postsynaptic cell (caused it to fire an action potential) by binding to AMPA receptors, the block on the NMDA receptors is removed, and glutamate can open the receptor channel and allow calcium to enter the cell. LTP is the result.
For NMDA receptors to pass calcium, both presynaptic and postsynaptic cell must be active. This is the basic requirement for Hebbian plasticity.
The rise in calium inside the post synaptic cell then leads to the activation of kinases that travel to the cell nucleus where addttional molecular processes occur, including gene activation, which in turn lads to the synthesis of new protein that contribute to the strengthing the synapses.
When synaptic activity in the strong pathway activated the postsynaptic cell, the block on NMDA receptors will be removed, even at weak synapses.
NMDA receptors ...... they are able to register that presynaptic and postsynaptic neurons were active at the same time.引自 Small change
It has been known for several decades that if animals are given drugs that prevent the brain from making new proteins, they are able to learn normally but are unable to form long-lasting memories.引自 Small change
这里有个定义,第二信使:
Their job is to initiate chemical recation within the cell on the basis of information provided from outsaide the cell during neurotransmission by first messengers.引自 Small change
这里介绍了启动kinases 对于AMPA受体的作用。
As a result, after the induction of LTP, the same amount of glutamate released from the presynaptic cell by an action potential will have more AMPA receptors to bind to.引自 Small change
关于突触前神经元在这个过程中是否发生改变目前还有争议。
One possible way this could happen is by the means of retrograde messengers, substances released by the postsynaptic cell after LTP is induced and taken up by the presynaptic terminal, which cause changes in the case of glutamate release here.引自 Small change
When the new proteins are subsequently made in the cell body, they are then shipped out to essentially all possible synapses in the cell, but only synapses that were tagged during the initial stimulation are able to use the new proteins to stabilized the connection with the presynaptic terminal.
Weak HFS leads to a short-lasting form of LTP (early LTP) that does not require gene expression and protein synthesis. However, it does creat the tag.引自 Small change
除了树突自己的变化。
The other part of the explanation is related to the actual growth of new synapses.
Recent studies demonstrate that proteins can be synthesized in denderites.引自 Small change
再接着介绍了阻断NMDA受体的小鼠进行水迷宫实验的情况。
Particular difficult to ascertain has been the issue of whether NMDA blockade produces a specific effect on learning itself, or instead changes other less specific capacities, such as the ability to preceive a given stimulus or the ability of desire to perform the appropriate response.引自 Small change
In some studies, hippocampal-dependent learning is unaffected by treatments that block LTP. This type of result, though, has been fairly rare, and centainly is not compelling enough to undermine the whole field. Futher, we now know that there are variety of different forms of LTP, some involving NMDA receptors and some not......引自 Small change
这里说了这么多,但都没有直接证明外显的学习与LTP的关系。
Rogan instead started with a circuit known to be involved in fear conditioning and then asked whether LTP occured in that circuit. The reversal of the strategy (starting with a learning circuit and looking for plasticity in it, rather then starting with a form of plasticiy and asking how it might related to learning) turned out to be very advantageous.引自 Small change
他用声音做条件刺激,电击做无条件刺激。在成功配对后,单独呈现声音也在杏仁核的相关区域引起LTP。
Indeed, Rogan's results showed that fear conditioning and LTP induction produced very similar changes in the electrical responses of amygdala cells to sound stimuli.
In spatial learning, a rat is free to learn about any of the may stimuli present in the environment, making it difficult to determine, in Hebbian terms, precisely what's being asspciated with what. INcontrast, fear conditioning is a straightforward form of associative learning that is easy to define in terms of Hebbian plasticity, where strong (foot shock) and weak (sound) stimuli interact at synapses on the same cells.
......disruption in the lateral amygdala of protein syntheisis or of some of the same kinases that prevent the induction of late LTP in the hipppcampus interferes with the formation of long-term memory for fear conditioning without affecting short-term memory.
Fear conditioning and lateral amygdala LTP thus seem to require the same mix of molecules that has been implicited in synaptic plasiticy and memory in the hippocampus.引自 Small change
最后总结了下这些研究更广泛的意义,以及一些未解决的问题。
Also unsolved is the locus of memory storage - plasticity in the lateral amygdala is clearly involved, but whether this is the only site of change that is maitiained over time remains to be determined.引自 Small change
接着介绍了一种消除创伤后记忆的可能办法,穿越虫洞上也提到过。
That is, if you take a memory out of storage you have to make new proteins (you have to store, or reconsolidate it) in order for the memory to remain a memory.引自 Small change
p162.
用无脊椎动物中海兔属的的实验来当做例子,介绍这个领域的研究。
The gill withdrawal reflex exhibits several forms of learning, including habituation: the gill retracts less if the mantle is touched repeatedly...... Habituation can reversed rapidly by giving a strong stimulus, such as an electric shock, to some other part of the mollusk's body, like the tail. Touch of the mantle after a shock results in a big response. This is an independent form of nonassociative learning called sensitization.
Associative learning - namely, classical defense or fear conditioning - also occurs in the gill withdrawal reflex.
Conditioning and sensitzation are similar in that a strong stimulus changes the response to a weak one. But they differ in specificity: in associative conditioning, the amplified response only occurs in the reaction to a stimulus that was paired with the shock, whereas in sensitization the response to stimuli that have no relation to the shock is bigger.引自 Small change
The serotonin binds to serotonin receptors located on the presynaptic axon terminal, and leads to the activation of protein kinase A (PKA), whichi results in a greater amount of glutamate release and thus a bigger postsynaptic response.
Because the increase in the efficiency of transmission between the sensory and motor neuron is due entirely to alteration in the sensory seuron terminal, it is refered to as presynaptic facilitation. Because the state of the activity of the postsynaptic neuron is irrelevant sensitization by dedinition is a form of non-Hebbian plasticity.
The two effects (persistent of PKA and formation of new connections) combine to produce long-lasting increase in transmission between the sensory and motor neurons, and stronger reflex responses.引自 Small change
One way of understanding this is that nonassociative (non-Hebbian) presynaptic facilitation functions as the presynaptic component of associative (Hebbian) plasticity.
Also the possibility that fear conditioning, amygdala LTP, and several forms of hippocampal plasticity might, like plasticity in Aplysia, involve presynaptic as well as postsynaptic changes futher strengthens the notion similar mechanisms are used to make memories in diverse species.引自 Small change
最后讲了变种果蝇的研究。
When given the choice between going into a chamber that contained an odor associated with the shock and a chamber that held a different oder, the flies oftern avoided the former chamber.
It is important to keep in mind that a mutant animal goes through its entire life with the genetic alteration, sometimes making it difficult to distinguish effects on learning and memory from other more general consequences of having grown up without certain proteins and their and products.
In each of this mutants, learning actually did take place to come extent, but then decayed rapidly after training.引自 Small change
通过集中学习和分散学习间的差距来测量记忆的效果。
......increase the level of gene transcription factor CREB available in flies at the time just before training...... with extra CREB, a single training trail could accomplish what required multiple trails in normal flies - creat a memory that lasts for days.引自 Small change
关于记忆,最重要的一点: It's a reconstruction of facts and experiences on the basis of the way they were stored, not as they actually occured. 接着从1904年一个德国科学家寻找engram,到Lashley,再到H.M引出的海马,简单的梳理了下对记忆的探索。 ......engram to refer to the neural representation of a memory. It seemed that the memory loss was related more to the size of the lesion than to its place...
2015-02-09 17:162人喜欢
关于记忆,最重要的一点:
It's a reconstruction of facts and experiences on the basis of the way they were stored, not as they actually occured.引自 Adventures in time
......engram to refer to the neural representation of a memory.
It seemed that the memory loss was related more to the size of the lesion than to its placement in the cortex.
He used a behavioral task that could be solved in different ways.
As the lesions got bigger, more processes were distrupted, leaving the animal with fewer options for solving the problem.
H.M could recall many of the events of his earlier life, especially those that occured up to several years before the surgery, he was unable to form memories for experiences that occured after the surgery, hewas unable to form memories for a few seconds (he had short-term memories), but he couldn't convert this information into long-term memories. He failed to recognize himself in a mirror, for example, but did recognize himself from old pictures.
Paul MacLean, the originator of the limbic system concept, conceived of the hippocampus as the seat of the Freudian id, a place in the brain where ideas could be mixed together and confused.引自 Adventures in time
p101.
开始介绍H.M.可以完成的一些任务。
然后关于记忆系统就有了新的认识。
Procedual memory was therefore later renamed with more neutral designation: nondeclaractive memory. The term explicit and implicit memory, suggested by Dan Schacter, essentially refer to the same memory processes as declarative and nondeclarative memory.
Outputs of each of the cortical areas then converge in the rhinal cortical areas, also known as the parahippocampal region, which integrates information from different sensory modalities before shipping it to the hippocampus proper.引自 Adventures in time
接着提到海马与新皮层之间的连接是相互的。
In this way, cortical areas involved in processing a stimulus can, as we will soon see, also participate in the long term storage of memories about that stimulus.
Convergence zones also allow mental representations to go beyond perceptions and to become conceptions - they make possible abstract representation s that are independent of the concrete stimulus.引自 Adventures in time
这种聚合区就像新皮层,在灵长类最多,哺乳动物次之。
接着区分了一下顺行性遗忘和逆行性遗忘。
There are basically two kinds of amnesia: one is an inability to remember things that happenred before the surgery or brain injury (called retrograge amnesia), and the other is an inability to form new memories (called anterograde amnesia). While we' ve focused so far on anterograde amnesia, both forms are present in patient with damage to the temporal lobe. Interestingly, the degree of retrograde amnesia is graded over time - memory is worse for events right before the surgery than for earlier ones.
The graded effect of retrograde amnesia is now believed to occur because the role of hippocampus changes over time - the hippocampus is needed for memory storage initially, butits role decreases as time goes by.引自 Adventures in time
对此有一种基于connectionist modeling的解释。
So-called interleaved learning prevents new information from interfering with old memories.引自 Adventures in time
But with the interleaved learning, where the reoresentaion is built up slowly over many repetitions, the network gradually refines the representation......引自 Adventures in time
p107.
接着关于记忆从海马参与到逐渐皮层独立的可能做了讨论。
Each reinstatement changes cortical synapses a little. Because the reinstatement depend on the hippocampus, damage to the hippocampus affects recent memories, but not old ones that have already been consolidated in the cortex.引自 Adventures in time
接着提到了关于睡眠期间大脑活动的研究。
Subsequently, when the rats went to sleep, the neural patterns seemed to be repeated in the hippocampus, as if the rats were dreaming about the places they had explored.引自 Adventures in time
目前这方面证据还不充分,只是猜想。
然后提到关于新记忆受损比老记忆严重的另外一种可能的解释。
However, with time, the memory trace comes to involve more and more brain regions, especially cortical regions, so that damage to one area, like hippocampus, fails to produce a deficit, since the other areas compensate.
With time, hippocampal activity decreased and came to be unrelated to memory performance, while cortical activity increased and came to be related to the memory performance.引自 Adventures in time
这里提到了图尔文关于记忆的划分。
He argued that episodic memories are about personal experiences (things happened to you at a particular time and place), while semantic memories are about facts (things you come to know, but have not necessarily experienced)......Tulving suggested that episodic memory, which requires conscious recollection of the time and place of some personal experience, is particular characteristic of humans, whereas semantic memories, being the single storage of a fact rather than a personal experience, is within tha capacity of many animals.引自 Adventures in time
One is that episodic memory, while poor, is still present in the children, and that even a littlespisodic memory capacity may be sufficient to support a gooddeal of semantic knowledge......but episodic deficit may be more readily detect.引自 Adventures in time
第二是脑成像没有解剖可靠。
p110.
受到H.M启发,研究者开始在动物身上做实验。
If conscious retrieval was required, the hippocampus tended to be involved.引自 Adventures in time
介绍了Delayed nonmatch to sample,注意是选没出现过的那个。
It turned out, though, that the effects of the lesions were not due to damage to the amygdala or hippocampus, but to damage of surrounding parahippocampal region.引自 Adventures in time
H.M.的这块也受损了。
In sum it seems that the parahippocampal areas and hippocampus make unique contributions, and the delayed nonmatch to sample task reflects the parahippocampal more than the hippocampal contribution.引自 Adventures in time
接着就介绍了去年诺奖获得者的的研究成果,不知道是不是因此得奖的,听新闻上的描述至少也是类似的实验。
......different cells in the hippocampus are active at different locations.
One of the few tasks that hippocampal leision seemed to impair with any consistency was maze learning, a task that is often solved by spatial cues.引自 Adventures in time
然后就介绍了莫里斯水迷宫实验(Morris water maze)。
Damage to the hippocampus in the primates does produce deficits in spatial memory, along with deficit in nonspatial memory.引自 Adventures in time
关于海马还有一种认为其与declarative memory 关系密切。
Specifically, declarative memories are relational. Thus, activation of a declarative memories can be activated independent of the context in which they were established, and by stimuli other than those that were initially involved in the learning.引自 Adventures in time
Conjunction theory则认为海马将各通道的信息混合在一起,成为一个整体了。
In this theory, the original elements, though, are lost, having been formed into conjunctions, while in the relational theory, the elements remain discrete and the hippocampus links them together.引自 Adventures in time
还有一种改进版的configural theory。
The hippocampus learns conjunctions naturally and rapidly. When the hippocampus is damaged, the neocortex can be forced, through extensive training, to also learn conjunctions, but normally it does not do so.引自 Adventures in time
接着开始讲内隐记忆。
The systems that engage in implicit learning are not strictly speaking memory systems. They were designed to perform specific functions......plasticity (the ability to change as a result of experience) is simply a feature of the neuronal infrstructure of these systems that facilitated their operation.
In this sense, explicit memory is, in Stephen Jay Gould's term, an exaptation.引自 Adventures in time
p118.
这里介绍了经典条件反射和操作性条件反射。
The subject is passive involved in classical conditioning (the food comes when the stimulus occurs, regardless of what the subject is doing) but in operant conditioning, the subject responds in a certain way.引自 Adventures in time
The emphasis was on conditoning as a tool for sutdying bahavioral relevant neural changes rather than as a direct model of human memory.引自 Adventures in time
2000年诺奖得主Kandel也是这种研究角度。
接着有一个关于杏仁核的很好的总结。
It had been known that the amygdala plays an important role in fear responses and even learning to fear new stimuli.
The lateral nucleus of the amygdala (lateral amygdala) serves as the input zone. It receives information from the various senses, allowing the outside world to be monitored for threatening information.
When the lateral nucleus detects some threatening stimulus, the central nucleus initiates the expression of defensive behaviors.
The lateral amygdala gets inputs about the stimuli from two sources. It receives a crude but fast representation from subcortical area (the sensory thalamus) and a slower but more complete representation from cortical sensory areas.引自 Adventures in time
这里就是一般的high road 和low road了。
两条通路通向同一神经元。
The inputs reach the neurons...... As a result, the cells are then more capable of charging ahead if the cortical information condirms the threat, or of putting on the brakes if the cortical information establishes that no danger is present.引自 Adventures in time
作者这里还做了特别的提醒:
It should not be assumed that high road is aconscious route to the amygdala...... The amygdala engages in implicit processing, including implicit larning, regardless of which pathway provides it with sensory information. As with any other stimulus, we become consciously aware of an emotional stimulus only when that stimulus is processed by networks involved in something called working memory.引自 Adventures in time
接着讲了lateral nucleus的可塑性。
If an animal is lucky enough to survive one dangerous encounter, its brain should store as much about the experience as possible.引自 Adventures in time
p126.
这里讨论了条件反射所必须的脑区。
It was disovered that removal of entire neocortex had no effect on the ability of rabbits to be conditioned. In fact, eye blink conditioningcould occur following removal of the most forebrain, icluding the amygdala, hippocampus, and other areas.
These researcher showed that leisions of a certain areas of the cerebellum prevented conditioning, and that activity of neurons in thses areas changed during the course of conditioning.引自 Adventures in time
这些实验关注的不是眨不眨眼,而是接受外部刺激以及控制动作。
Control of precise movements at just the right time is a fundamental aspect of mauy of acquired brhavioral skill.引自 Adventures in time
接着开始讲味觉。
An infant will spit out spit bitter foods on the first encouter. Infants born with massive parts of the forebrain missing, and rats with lesions of all of the forebarin and midbrain still exhibit taste preferneces, suggest that taste mediated by the hindbrain.引自 Adventures in time
提到了关于taste aversion的条件反射(CTA)。
The taste path way from the tongue goes to a region of the hindbrain called nucleus of the solitary tract, which is involved in taste preferences. The same general region of the hindbrain receives fibers from the gut, telling the brain about nausea and other gastrointestinal conditions...... The two parts of the nucleus of the solitary tract do project onto a common area in the middle brain called parabrachial nucleus.
Removal of the forebrain, which leaves only the brain stem to run the show, disrupts the acquisition of CTA, in spite of the fact that the same procedure leaves taste prefenrences undisturbed. The parabrachial nucleus thus does not work alone in the mediation of CTA and instead depends on the forebrain areas.引自 Adventures in time
p129.
提了下实验中两种条件反射的联系。
But the first step is that the rat has to learn, through classical conditioning, that the tone predicts the shock.引自 Adventures in time
然后回到了有意识的记忆和无意识的记忆。
Hippocampal damage does not distrupt normal conscious awareness.引自 Adventures in time
The patients with hippocampal damage did not condition in the trace task.引自 Adventures in time
而正常被试当中:
Whether they conditioned was closely related to whether they reported, after the experiment, having noticed a relation between the tone and the puff...... This suggested that the trace conditioning requires awareness, and that the hippocampus mekes this awareness possible.引自 Adventures in time
接着介绍了另外一个实验,在一堆字母L(背景)中找字母T(目标),操作了L的样式。
The normals but not the amnesics benefited from the repetition of the background pattern: they were better at finding the T in the repeated pattern than novel ones......The hippocampus, in other words, was required to process and learn about the unattended background stimuli.引自 Adventures in time
Hippocampus......is able to put together many things at once, to relate or configure them into a context.
The key function of the hippocampus is probably processing relations.引自 Adventures in time
介绍了一下《记忆的七宗罪》这本书。
Even in the face of severe memory problems, its sufferers initially remain much the same person they always were —— they walk and talk the same, and have the same basic habits and traits. As the disease spreads widely to other brain areas, those that function implicitly, personality begins to break down.引自 Adventures in time
Brain development is the major battlefield of nature-nurture conflict. It is less common, but no less appropriate, to think of genes as also influencing us in the form of memory. In this case, though, the synaptic memory comes about as a resultif ancestral rather than personal history. 从胚胎阶段整个发育就有环境因素的参与。 The chemical environment of the embryo is, by necessity, in direct cont...
2015-02-04 11:201人喜欢
Brain development is the major battlefield of nature-nurture conflict.
It is less common, but no less appropriate, to think of genes as also influencing us in the form of memory. In this case, though, the synaptic memory comes about as a resultif ancestral rather than personal history.引自 Building the brain
从胚胎阶段整个发育就有环境因素的参与。
The chemical environment of the embryo is, by necessity, in direct contact with the body chemistry of the mother.
In the neural tube, nonneural precusor cells divide and give rise to neurons.
It's important to make a distinction here between neurogenesis——the birth of new neurons——and synaptogenesis——the creation of new synapses between existing neurons.引自 Building the brain
Segregation is under the direct control of a special set of genes called homeotic genes.
Segregated cells eventually differentiate, which means that they on different shapes and sizes, and end up with different transmitters and modulators.引自 Building the brain
这里发现化学环境对神经元最后的功能影响还是大的,特别是未分化的神经元。
As development proceeds, the neural tube expands and bends, eventually assuming a shape that begins to resemble the brain.引自 Building the brain
这里对于这些神经元的“命运”还是很有争论的。
One possibility is that the function of a cell is specified genetically, so that it is destined to end up in specific areas devoted to a specific function before it leaves the neural tube. Another possibility is that cells learn what to do from the context in which they end up.引自 Building the brain
这里作者依然强调突触比神经元本身对回路功能的贡献更大。
Once neurons reach their destinations, they begin to sprout axons.引自 Building the brain
这里有一些蛋白质作为attractant和repellent引导这个过程。
p72.
We probably don't have enough genes to account for the wiring of each of the brains's trillions of synaptic conncetions.引自 Building the brain
这样就产生了火热的争论:instruction 和 selection。
The exact role of neural activity, though, is heatedly debated, with the main issue of contention being whether activity, especially activity initiated by environmental stimulation, helps creat the mature connections or just selects from the initial set of intrinsically established connections those that will be retained.
Selectionists also assume that there's a good deal of randomness involved.引自 Building the brain
神经元会在发展过程中会死亡目前基本是确定的。
The key issue is not whether synapses are eliminated during development (they clear are) but instead whether the decreases that do occur provide conclusive support for strong version of selectionism - the version that claims that activity only prevents the elimination of synapses.引自 Building the brain
p76.
这里介绍了悲惨的独眼小猫。
Hubel and Wiesel concluded that the development of synapticconnections is a competitive proccess, one in which the connections that are used are kept and those that go unused are elimnated.引自 Building the brain
当然,实际情况比这个复杂。
They found that as development proceeded, mauy axons did indeed retract (consistent with a selectionist view), but that the remaining axons also increased in complexity (consistent with an instructional view).引自 Building the brain
It is probably best to think of instruction and selection as two complementary meas by which circuits can be constructed rather than as mutually exclusive theories of brain development.引自 Building the brain
It has taken tremendous amount of work to demonstrate that activity both instructs the formation of new connections and selects used ones from a preexisting pool.引自 Building the brain
p79.
赫布大神出场
In 1949, Donald Hebb, a Canadian psychologist, proposed that if two neurons are active ar the same time, and one is presynaptic to the other, then the connection between them will be strengthened.引自 Building the brain
这一章讲的比较简单,书的接下来还有大量篇幅涉及具体的机制。
Hebbian plasticity involves the released tranmitter to two kinds of postsynaptic receptors. One of these receptors records that the post cell was active, and the other records which presynaptic terminals contracting the postsynaptic cell were active at the same time.
NMDA receptors, appear to be particular important in that they are able to detect the match between activity in the presynaptic and post synaptic neuron.
Another important set of molecules are neurotrophins, special tonic that promote the survival and growth of neurons.引自 Building the brain
这种物质是从postsynaptic cell释放然后被presynaptic cell吸收的。
Cell death is prevented if a presynaptic terminal receives a life-sustaining shot of neurotrophins from postsynaptic partner.
The surviving terminals (those that were active) also begin to spout new connections.引自 Building the brain
p82.
开始讨论“先天”。
One is the
idea that genes make us all the same, giving us trait that we share with other members of our species. The other is that genes make us unique.引自 Building the brain
第一种取向介绍了动物行为学。
The classic method used by ethologists to test innateness was to show that a behavior was present at birth or shortly thereafter, or, mre generally, that it merged in the absence of an opportunity for the organism to have learned from environmental stimulation.引自 Building the brain
接着介绍了对于反驳行为主义的几个经典证据,让你恶心的东西更容易和食物建立联系。
The language may be innate is supported by studies of pidgin language, a simple, crude form of verbal communication among people who speak different languages but live together and have to communicate with one another. Pidgin lacks grammer when it is initially pieced together, but by the second generation, it begins to take on a grammatical structure.
It has been proposed that humans have innate knowledge about numbers, physics, and even about how other human mind work.引自 Building the brain
之后又提了下对于进化心理学的反驳。
其中比较重要的一个反驳是:
As Gould's exaptation argument points out, something can be innate (passed on genetically) even if the role it plays today is not the one form which it evolved.引自 Building the brain
Constructivists accept the principle that genes build the overall structure, and the regressive events like synaptic selection take place, but they argue that epigenetic prewiring and selection alone cannot explain cognition.引自 Building the brain
Together, these findings lead to the conclusion that genes help in the explanation of the behavioral difference between group but not within groups, at least in this case.
Genes may play a role in placing a function in the brain of every human, and at the same time make a relatively small contribution to differences in the way that function is wired in individuals.引自 Building the brain
An seldom is any brain function as complex as those involved in behavioral or mental process under the control of one gene.引自 Building the brain
接着介绍了关键期,敏感期对学习的影响。
Language learning is more flexible in children than in adults, as anyone who has tried to learn a second language after puberty knows.
Whether math or music learning has acritical period of synaptic development is not known.引自 Building the brain
这里有一个很有趣的观点:
the early years are crucial not because the window of opportunity closes but because what is learned at this time becomes the foundation of subsequent learning.引自 Building the brain
2 有用 Lucia 2016-04-28
全部是事实和理论,没有可以校准行为的反馈,看不下去
0 有用 蝉 2013-12-26
:无
0 有用 Y7UK2 2016-10-19
水平有限,只看懂一点皮毛
0 有用 莎翁 2020-06-08
在网上找的各类此书版本排版和错误简直令人绝望...
0 有用 weihu 2016-09-11
看看
0 有用 C.Oreki 2021-01-06
ledoux就像一个大学里随处可见的教授,自己做着还算有用或有趣的研究,但授课方式一板一眼枯燥无味,没有大量背景或者对内容本身感兴趣的话根本听不下去。我以为这是一本科普,但ledoux生生把它写成了教科书+文献综述,偶尔穿插着一些干巴巴的个人观点。这人在象牙塔里待了太久,思维方式纯学术式,和现实世界基本对接不上了。最后四五章值得一读,但时刻记住,多数实验在小鼠或灵长类动物身上完成,私认为不能直接拓... ledoux就像一个大学里随处可见的教授,自己做着还算有用或有趣的研究,但授课方式一板一眼枯燥无味,没有大量背景或者对内容本身感兴趣的话根本听不下去。我以为这是一本科普,但ledoux生生把它写成了教科书+文献综述,偶尔穿插着一些干巴巴的个人观点。这人在象牙塔里待了太久,思维方式纯学术式,和现实世界基本对接不上了。最后四五章值得一读,但时刻记住,多数实验在小鼠或灵长类动物身上完成,私认为不能直接拓展于人脑。对neuroscience有种幻灭感,还是metzinger那样的哲学家有意思。 (展开)
0 有用 莎翁 2020-06-08
在网上找的各类此书版本排版和错误简直令人绝望...
1 有用 Sprittte 2017-08-04
数年前尝试读过,没读懂;去年重读,些微懂了些。讲突触是如何形成,变化,且定义自我的。要注意心理学家对「情绪」的定义,与大众印象中的「情绪」并不相同。脑科学很好的科普入门书。
0 有用 Y7UK2 2016-10-19
水平有限,只看懂一点皮毛
0 有用 weihu 2016-09-11
看看