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Behavioral/Systems/Cognitive Signal Propagation and Logic Gating in Networks of
 

Summary: Behavioral/Systems/Cognitive
Signal Propagation and Logic Gating in Networks of
Integrate-and-Fire Neurons
Tim P. Vogels and L. F. Abbott
Volen Center for Complex Systems and Department of Biology, Brandeis University, Waltham, Massachusetts 02454-9110
Transmission of signals within the brain is essential for cognitive function, but it is not clear how neural circuits support reliable and
accurate signal propagation over a sufficiently large dynamic range. Two modes of propagation have been studied: synfire chains, in
which synchronous activity travels through feedforward layers of a neuronal network, and the propagation of fluctuations in firing rate
across these layers. In both cases, a sufficient amount of noise, which was added to previous models from an external source, had to be
includedtosupportstablepropagation.Sparse,randomlyconnectednetworksofspikingmodelneuronscangeneratechaoticpatternsof
activity. We investigate whether this activity, which is a more realistic noise source, is sufficient to allow for signal transmission. We find
that, for rate-coded signals but not for synfire chains, such networks support robust and accurate signal reproduction through up to six
layers if appropriate adjustments are made in synaptic strengths. We investigate the factors affecting transmission and show that
multiplesignalscanpropagatesimultaneouslyalongdifferentpathways.Usingthisfeature,weshowhowdifferenttypesoflogicgatescan
arise within the architecture of the random network through the strengthening of specific synapses.
Key words: rate coding; sensory processing; propagation; integrate-and-fire neurons; network models; synfire chains; logic gates
Introduction
Cognitive processing involves signal propagation through multi-
ple brain regions and the activation of large numbers of specific
neurons. Computational approaches are useful for studying the

  

Source: Abbott, Laurence - Center for Neurobiology and Behavior & Department of Physiology and Cellular Biophysics, Columbia University

 

Collections: Biology and Medicine