Cortical hierarchies, sleep, and the extraction of knowledge from memory
Cortical hierarchies, sleep, and the extraction of knowledge from memory
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DOI：
10.1016/j.artint.2009.11.013
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发表时间：
2010-02-01
影响因子：
14.4
通讯作者：
McNaughton, Bruce L.
中科院分区：
文献类型：
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作者：
McNaughton, Bruce L.
众神之父奥丁手下有两只大乌鸦。这些乌鸦的名字是Hugin（思想）和Munin（记忆），每天黎明时分，它们都会飞越Midgard（世界）寻找新闻和信息，以了解更多关于人类及其活动的信息。在日落时，他们会回到奥丁那里，在奥丁的肩膀上各坐一个，在他耳边低语他们所看到和听到的一切。经验，作为记忆储存在大脑中，是智力和思想的原材料。已经提出在日落时（即，在睡眠期间），大脑调整其自身的突触矩阵，以通过梯度下降优化过程来实现对未来事件的自适应响应，该梯度下降优化过程涉及最近和较旧记忆的重复再激活以及突触权重的逐渐调整。记忆检索、思维和适应性行为反应的产生涉及通过神经元状态空间的全局协调轨迹，由适当的突触连接介导。人工神经网络被设计为实现甚至最基本形式的记忆和知识提取以及自适应行为，其包含大量对称互连的节点;然而，在大脑皮层中，任意两个任意选择的细胞之间的突触连接的概率是10（-6）的量级，即，如此接近于零，以至于天真的建模者可能会完全忽略这个参数。对称连接的概率甚至更小（10（-12））。那么，思想和记忆又是如何可能的呢？解决方案似乎是模块化、层次化的皮层结构的进化，在这种结构中，模块内部高度连接，但与其他模块的连接很弱。适当的模块间联系是间接介导的，通过共同的联系与更高级别的模块统称为关联皮层。颞叶的海马结构是最高层的联合皮层。它产生的顺序耦合模式的位置和内容的经验，但不包含实际存储的数据。相反，模式充当指向数据的指针或“链接”。在睡眠期间，这些连接模式的自发重新激活可能使存储在皮层较低水平的最近经验序列得以检索，并逐渐从中提取知识。在这篇文章中，我探讨了这些想法，它们的含义，以及它们的神经科学证据。(C)2009年由Elsevier B. V.出版
Odin the Allfather had in his service two great ravens. These ravens' names were Hugin (Thought) and Munin (Memory) and every morning at dawn they would fly off over Midgard (the world) in search of news and information to learn more about humans and their activities. At sundown, they would return to Odin where they would perch one on each of Odin's shoulders, and whisper into his ears all that they had seen and heard. Experience, stored in the brain as memory, is the raw material for intelligence and thought. It has been suggested that at sundown (i.e., during sleep) the brain adjusts its own synaptic matrix to enable adaptive responses to future events by a process of gradient descent optimization, involving repeated reactivations of recent and older memories and gradual adjustment of the synaptic weights. Memory retrieval, thought, and the generation of adaptive behavioral responses involve globally coordinated trajectories through the neuronal state-space, mediated by appropriate synaptic linkages. Artificial neural networks designed to implement even the most rudimentary forms of memory and knowledge extraction and adaptive behavior incorporate massively and symmetrically interconnected nodes; yet, in the cerebral cortex, the probability of a synaptic connection between any two arbitrarily chosen cells is on the order of 10(-6), i.e., so close to zero that a naive modeler might neglect this parameter altogether. The probability of a symmetric connection is even smaller (10(-12)). How then, are thought and memory even possible? The solution appears to have been in the evolution of a modular, hierarchical cortical architecture, in which the modules are internally highly connected but only weakly interconnected with other modules. Appropriate inter-modular linkages are mediated indirectly via common linkages with higher level modules collectively known as association cortex. The hippocampal formation in the temporal lobe is the highest level of association cortex. It generates sequentially coupled patterns unique to the location and content of experience, but which do not contain the actual stored data. Rather, the patterns serve as pointers or 'links' to the data. Spontaneous reactivation of these linking patterns during sleep may enable the retrieval of recent sequences of experience stored in the lower levels of the cortex and the gradual extraction of knowledge from them. In this essay I explore these ideas, their implications, and the neuroscientific evidence for them. (C) 2009 Published by Elsevier B.V.