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From Brain Science to Intelligent Machines

Dynamics of recurrent neural network and its implication for higher order cognitive function

Date: Tuesday26/04/2016

Venue: MS020

Time: 10.00 am

Speaker:    Prof. Da-Hui Wang

Affiliation:  Beijing Normal University, China

                 

Dynamics of recurrent neural network and its implication for higher order cognitive function

By 

Prof. Da-Hui Wang

Beijing Normal University, China

Abstract

The cortical part of the brain has plenty of recurrent connectivity, which provides rich repertoire of neural circuit dynamics, and providing neural substrates for higher order cognitive functions such as working memory and decision-making. In this talk, I will discuss how the dynamics of a recurrent network implements multiple-item visual working memory and discrimination between multiple alternative motion directions formed by random moving dots. In the network, neurons are uniformly placed on a ring, labeled by their preferred directions. The connections between excitatory pyramidal cells are structured as a Gaussian function of the difference in the preferred directions, and the connections onto and from the inhibitory interneurons are uniform. The excitatory synaptic currents are mainly mediated by NMDA receptors. This network can simultaneously elicit multiple localized activities after withdrawal of external stimulations, representing the memorization of multiple items. The competition between excitation and inhibition determines the fading/merging of localized activity, furthering the capacity of working memory. The network can be reduced as an analytically tractable, partial integro-differential system. Using nonlinear dynamical analysis, we characterize the multiple-choice decision behaviors and the time course of neural activities underlying decisions, providing a mechanistic explanation for the observations noted in the experiments.

Short Bio

Da-Hui Wang is a Professor in the School of Systems Science and State Key Laboratory for Cognitive Neuroscience and Learning, at Beijing Normal University (BNU), China. He obtained his PhD in systems theory in 2002 from BNU. Dr. Wang focuses on the complexity in neural system, especially, the neural dynamics underlying cognitive function such as working memory, decision-making, and neural modulation.