TR on Working Memory in PFC and BG

[Randall C. O'Reilly]

The following technical report is now available for downloading from:
http://psych.colorado.edu/~oreilly/pubs-abstr.html#03_pbwm

				- Randy

    Making Working Memory Work: A Computational Model of Learning
	     in the Prefrontal Cortex and Basal Ganglia

			 Randall C. O'Reilly

		       Department of Psychology
			University of Colorado
			  Boulder, CO 80309

		      ICS Technical Report 03-03

Abstract:

The prefrontal cortex has long been thought to subserve both working
memory (the holding of information online for processing) and
``executive'' functions (deciding how to manipulate working memory and
perform processing). Although many computational models of working
memory have been developed, the mechanistic basis of executive
function remains elusive. In effect, the executive amounts to a
homunculus. This paper presents an attempt to deconstruct this
homunculus through powerful learning mechanisms that allow a
computational model of the prefrontal cortex to control both itself
and other brain areas in a strategic, task-appropriate manner. These
learning mechanisms are based on structures in the basal ganglia (NAc,
VTA, striosomes of the dorsal striatum, SNc) that can modulate
learning in other basal ganglia structures (matrisomes of the dorsal
striatum, GP, thalamus), which in turn provide a dynamic gating
mechanism for controlling prefrontal working memory
updating. Computationally, the learning mechanism is designed to
simultaneously solve the temporal and structural credit assignment
problems. The model's performance compares favorably with standard
backpropagation-based temporal learning mechanisms on the challenging
1-2-AX working memory task, and other benchmark working memory tasks.

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| Dr. Randall C. O'Reilly   |                                    |
| Associate Professor       | Phone: (303) 492-0054              |
| Department of Psychology  | Fax:   (303) 492-2967              |
| Univ. of Colorado Boulder |                                    |
| 345 UCB                   | email: oreilly at psych.colorado.edu  |
| Boulder, CO 80309-0345    | www:   psych.colorado.edu/~oreilly |
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