Entorhinal but Not Hippocampal or Subicular Lesions Disrupt Latent Inhibition in Rats

E. Coutureau, R. Galani, O. Gosselin, M. Majchrzak, G. Di Scala
Neurobiology of Learning and Memory. 1999-11-01; 72(3): 143-157
DOI: 10.1006/nlme.1998.3895

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1. Neurobiol Learn Mem. 1999 Nov;72(3):143-57.

Entorhinal but not hippocampal or subicular lesions disrupt latent inhibition in
rats.

Coutureau E(1), Galani R, Gosselin O, Majchrzak M, Di Scala G.

Author information:
(1)Laboratoire de Neurosciences Comportementales et Cognitives, UMR 7521 CNRS,
Strasbourg, France. *protected email*

Latent inhibition (LI) is the deficit of conditioning resulting from repeated
nonreinforced preexposure to a conditioned stimulus before its pairing with an
unconditioned stimulus. There are cumulative data showing that large lesions of
the hippocampal formation disrupt LI. However, the effects of selective lesions
of the different components of the hippocampal formation have never been directly
addressed in the same study and conditioning paradigm. The first experiment of
the present study aimed at investigating the effects of excitotoxic lesions of
the hippocampus, subiculum, or entorhinal cortex on LI in an
« off-baseline »-conditioned emotional response procedure. Hippocampus or subiculum
lesions had no effect on either LI or conditioning. In contrast, entorhinal
cortex lesions disrupted LI without modifying conditioning. In Experiment 2,
locomotor activity in a novel environment was assessed in the same rats. Whereas
lesions of hippocampus increased locomotor activity, lesions of the subiculum or
the entorhinal cortex were devoid of effect. Although both LI and habituation to
novel environmental cues are thought to involve interactions between the
hippocampal formation and the mesolimbic pathway, these results indicate a
functional dissociation between the hippocampus and the entorhinal cortex.

Copyright 1999 Academic Press.

DOI: 10.1006/nlme.1998.3895
PMID: 10536094 [Indexed for MEDLINE]


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