Associative encoding in anterior piriform cortex versus orbitofrontal cortex during odor discrimination and reversal learning.

Full Abstract

Recent proposals have conceptualized piriform cortex as an association cortex, capable of integrating incoming olfactory information with descending input from higher order associative regions such as orbitofrontal cortex (OFC). If true, encoding in piriform cortex should reflect associative features prominent in these areas during associative learning involving olfactory cues. To test this hypothesis, we recorded from neurons in OFC and anatomically related parts of the anterior piriform cortex (APC) in rats, learning and reversing novel odor discriminations. Findings in OFC were similar to what we have reported previously, with nearly all the cue-selective neurons exhibiting substantial plasticity during learning and reversal. Also, many of the cue-selective neurons were originally responsive in anticipation of the outcomes early in learning, thereby providing a single-unit representation of the cue-outcome associations. Some of these features were also evident in firing activity in APC, including some plasticity across learning and reversal. However, APC neurons failed to reverse cue selectivity when the associated outcome was changed, and the cue-selective population did not include neurons that were active prior to outcome delivery. Thus, although representations in APC are substantially more associative than expected in a purely sensory region, they do appear to be somewhat more constrained by the sensory features of the odor cues than representations in downstream areas of OFC.

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Author information

Author/s: Roesch, Matthew R (MR); Stalnaker, Thomas A (TA); Schoenbaum, Geoffrey (G);

Affiliation: Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA. mroes001(-atsign-)umaryland.edu

Grants: DA015718 (Agency:NIDA NIH HHS) ; R01 DA015718-04 (Agency:NIDA NIH HHS) ; T32-DC00054 (Agency:NIDCD NIH HHS) ; T32-NS07375 (Agency:NINDS NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural

Journal: Cerebral cortex (New York, N.Y. : 1991) (Cereb Cortex), published in United States. (Language: eng)

Reference: 2007-Mar; vol 17 (issue 3) : pp 643-52

Dates: Created 2007/02/09; Completed 2007/04/18; Revised 2008/11/20;

PMID: 16699083, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Animals
Association Learning - physiology
Discrimination Learning - physiology
Electrophysiology
Frontal Lobe - cytology; physiology
Male
Neural Pathways

Neural Pathways
Odors
Olfactory Pathways - cytology; physiology
Rats
Rats, Long-Evans
Reversal Learning - physiology
Smell - physiology

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