Friday, September 07, 2007
Yasser Roudi*, Peter E. Latham
A critical component of cognition is memory—the ability to store information, and to readily retrieve it on cue. Existing models postulate that recalled items are represented by self-sustained activity; that is, they are represented by activity that can exist in the absence of input. These models, however, are incomplete, in the sense that they do not explain two salient experimentally observed features of persistent activity: low firing rates and high neuronal variability. Here we propose a model that can explain both. The model makes two predictions: changes in synaptic weights during learning should be much smaller than the background weights, and the fraction of neurons selective for a memory should be above some threshold. Experimental confirmation of these predictions would provide strong support for the model, and constitute an important step toward a complete theory of memory storage and retrieval.
. . .we no longer know how the brain holds so many memories. Roudi and Latham speculate that the answer lies in multiple, weakly coupled networks. However, until that, or some other idea, is shown to be correct, we will have to be content with just remembering, without the added knowledge of how we remember.
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