Neural Computation, Vol 8, 1245-1265, Copyright © 1996 by The MIT Press
Spike train processing by a silicon neuromorph: the role of sublinear summation in dendrites
DP Northmore and JG Elias
Department of Psychology, University of Delaware, Newark 19716, USA.
A dendritic tree, as part of a silicon neuromorph, was modeled in VLSI as a
multibranched, passive cable structure with multiple synaptic sites that
either depolarize or hyperpolarize local "membrane patches," thereby
raising or lowering the probability of spike generation of an
integrate-and-fire "soma." As expected from previous theoretical analyses,
contemporaneous synaptic activation at widely separated sites on the
artificial tree resulted in near-linear summation, as did neighboring
excitatory and inhibitory activations. Activation of synapses of the same
type close in time and space produced local saturation of potential,
resulting in spike train processing capabilities not possible with linear
summation alone. The resulting sublinear synaptic summation, as well as
being physiologically plausible, is sufficient for a variety of spike train
processing functions. With the appropriate arrangement of synaptic inputs
on its dendritic tree, a neuromorph was shown to discriminate input pulse
intervals and patterns, pulse train frequencies, and detect correlation
between input trains.
