Multiplicative Shot Noise: A New Route to Stability of Plastic Networks
Professor Johnatan (Yonatan) Aljadeff
(Neurobiology, UCSD)
ABSTRACT
Fluctuations of synaptic-weights, among many other physical, biological and ecological quantities, are driven by coincident events originating from two `parent' processes. We propose a multiplicative shot-noise model that can capture the behavior of a broad range of such natural phenomena, and analytically derive an approximation that accurately predicts its statistics. We apply our results to study the effects of a multiplicative synaptic plasticity rule that was recently extracted from measurements in physiological conditions. Using mean-field theory analysis and network simulations we investigate how this rule shapes the connectivity and dynamics of recurrent spiking neural networks. We show that the multiplicative plasticity rule, without fine-tuning, gives a stable, unimodal synaptic-weight distribution with a large fraction of strong synapses. The strong synapses remain stable over long times but do not `run away'.
Our results suggest that the multiplicative plasticity rule offers a new route to understand the tradeoff between flexibility and stability in neural circuits and other dynamic networks.
Joint work with Bin Wang
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