TR on Hippocampus and Neocortex

[Randall C. O'Reilly]

The following technical report is now available for downloading as:
ftp://grey.colorado.edu/pub/oreilly/papers/oreillyrudy99_hipconj_tr.ps

				- Randy

	 Conjunctive Representations in Learning and Memory:
	   Principles of Cortical and Hippocampal Function

		Randall C. O'Reilly and Jerry W. Rudy

		       Department of Psychology
			University of Colorado
			  Boulder, CO 80309

		      ICS Technical Report 99-01

Abstract:

We present a theoretical framework for understanding the roles of the
hippocampus and neocortex in learning and memory.  This framework
incorporates a theme found in many theories of hippocampal function,
that the hippocampus is responsible for developing conjunctive
representations binding together stimulus elements into a unitary
representation that can later be recalled from partial input cues.
This idea appears problematic, however, because it is contradicted by
the fact that hippocampally lesioned rats can learn nonlinear
discrimination problems that require conjunctive representations.  Our
framework accommodates this finding by establishing a principled
division of labor between the cortex and hippocampus, where the cortex
is responsible for slow learning that integrates over multiple
experiences to extract generalities, while the hippocampus performs
rapid learning of the arbitrary contents of individual experiences.
This framework shows that nonlinear discrimination problems are not
good tests of hippocampal function, and suggests that tasks involving
rapid, incidental conjunctive learning are better.  We implement this
framework in a computational neural network model, and show that it
can account for a wide range of data in animal learning, thus
validating our theoretical ideas, and providing a number of insights
and predictions about these learning phenomena.

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| Dr. Randall C. O'Reilly        |                                            |
| Assistant Professor            |                                            |
| Department of Psychology       | Phone: (303) 492-0054                      |
| University of Colorado Boulder | Fax:   (303) 492-2967                      |
| Muenzinger D251C               | Home:  (303) 448-1810                      |
| Campus Box 345                 | email:  oreilly at psych.colorado.edu         |
| Boulder, CO 80309-0345         | www:    http://psych.colorado.edu/~oreilly |
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