IRCS Colloquium: Professor Misha Tsodyks: Synaptic theory of working memory

Misha Tsodyks

Department of Neurobiology
Weizmann Institute of Science

http://www.weizmann.ac.il/home/bnmisha/

Synaptic theory of working memory

We recently proposed that short-term working memory could be residing in
selective facilitation of recurrent connections in dedicated neocortical
circuits. This mechanism can account for low persistent firing rates
observed in monkeys performing delayed memory tasks, and is robust to
external perturbations. In this presentation I will extend the theory to
the case of continuous variables, such as orientation, and show that
synaptic facilitation can dramatically increase the stability of memory
to random perturbation of connectivity. I will also present our analysis of
recordings of large number of single neurons in prefrontal cortex of
monkeys performing parametric working memory tasks, obtained in the
laboratory of Professor Ranulfo Romo. The results of the analysis show
that information about the stimulus in the delay period is encoded in a
highly dynamic manner, in particular the population activity does not
faithfully represent the stimulus for for a certain period during the
delay. Synaptic facilitation can account for some of the features of the
data.

http://www.ircs.upenn.edu/colloq/2009/fall/tsodyks.htm