Why does brain damage impair memory? A connectionist model of object recognition memory in perirhinal cortex

Cowell, Rosemary A. and Bussey, Timothy J. and Saksida, Lisa M. (2006) Why does brain damage impair memory? A connectionist model of object recognition memory in perirhinal cortex. Journal of Neuroscience, 26 (47). pp. 12186-12197. ISSN 1529-2401 (Electronic). (Full text available)

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Abstract

Object recognition is the canonical test of declarative memory, the type of memory putatively impaired after damage to the temporal lobes. Studies of object recognition memory have helped elucidate the anatomical structures involved in declarative memory, indicating a critical role for perirhinal cortex. We offer a mechanistic account of the effects of perirhinal cortex damage on object recognition memory, based on the assumption that perirhinal cortex stores representations of the conjunctions of visual features possessed by complex objects. Such representations are proposed to play an important role in memory when it is difficult to solve a task using representations of only individual visual features of stimuli, thought to be stored in regions of the ventral visual stream caudal to perirhinal cortex. The account is instantiated in a connectionist model, in which development of object representations with visual experience provides a mechanism for judgment of previous occurrence. We present simulations addressing the following empirical findings: (1) that impairments after damage to perirhinal cortex (modeled by removing the perirhinal cortex layer of the network) are exacerbated by lengthening the delay between presentation of to-be-remembered itemsandtest, (2) that such impairments are also exacerbated by lengthening the list of to-be-remembered items, and (3) that impairments are revealed only when stimuli are trial unique rather than repeatedly presented. This study shows that it may be possible to account for object recognition impairments after damage to perirhinal cortex within a hierarchical, representational framework, in which complex conjunctive representations in perirhinal cortex play a critical role.

Item Type: Article
Uncontrolled keywords: inferotemporal cortex, configural, hippocampus, visual perception, medial temporal lobe, ventral visual stream, interference
Subjects: Q Science > QA Mathematics (inc Computing science) > QA 76 Software, computer programming,
Divisions: Faculties > Science Technology and Medical Studies > School of Computing > Computational Intelligence Group
Depositing User: Mark Wheadon
Date Deposited: 29 Mar 2010 12:11
Last Modified: 14 Apr 2014 15:58
Resource URI: http://kar.kent.ac.uk/id/eprint/24044 (The current URI for this page, for reference purposes)
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