Perplexing effects of hippocampal lesions on latent inhibition: a neural network solution.


Journal Article (Review)

Experimental data indicate that hippocampal lesions might impair, spare, or even facilitate latent inhibition (LI). Furthermore, when LI is impaired by the lesions, it might be reinstated by haloperidol administration. The present article applies a neural network model of classical conditioning (N. A. Schmajuk, Y. W. Lam, & J. A. Gray, 1996) to investigate the possible causes of these puzzling results. According to the model, LI is manifested because preexposure of the conditioned stimulus (CS) reduces Novelty, defined as proportional to the sum of the mismatches between predicted and observed events, thereby reducing attention to the CS and retarding conditioning. It is assumed that hippocampal lesions affect the prediction of events. Computer simulations reveal that, depending on the behavioral protocol (i.e., procedure and total time of CS preexposure), Novelty in hippocampal lesioned animals might be larger, equal, or smaller (corresponding to smaller, equal, or larger LI) than in normal controls. Reinstatement of LI by haloperidol administration is explained by assuming that dopaminergic antagonists decrease the value of Novelty, when Novelty increases following hippocampal lesions.

Full Text

Cited Authors

  • Buhusi, CV; Gray, JA; Schmajuk, NA

Published Date

  • April 1998

Published In

Volume / Issue

  • 112 / 2

Start / End Page

  • 316 - 351

PubMed ID

  • 9588481

Pubmed Central ID

  • 9588481

Electronic International Standard Serial Number (EISSN)

  • 1939-0084

International Standard Serial Number (ISSN)

  • 0735-7044

Digital Object Identifier (DOI)

  • 10.1037//0735-7044.112.2.316


  • eng