Associative encoding in posterior piriform 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 and basolateral amygdala (ABL). If true, encoding in piriform cortex should reflect associative features prominent in these areas during associative learning involving olfactory cues. We recently reported that neurons in anterior piriform cortex (APC) in rats exhibited significant plasticity in their responses to odor cues during associative learning. Here, we have repeated this study, recording from neurons in posterior piriform cortex (PPC), a region of piriform cortex that receives much stronger input from ABL. If associative encoding in piriform cortex is driven by inputs from ABL, then we should see more plasticity in PPC neurons than we observed in APC. Consistent with this hypothesis, we found that PPC neurons were highly associative and appeared to be somewhat more likely than neurons recorded in APC to alter their responses to the odor cues after reversal of the odor-outcome associations in the task. Further, odor-selective PPC populations exhibited markedly different firing patterns based on the valence of the odor cue. These results suggest associative encoding in piriform cortex is represented in a topographical fashion, reflecting the stronger and more specific input from olfactory bulb concerning the sensory features of odors in anterior regions and stronger input from ABL concerning the meaning of odors in posterior regions.

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Author information

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

Affiliation: Program in Neuroscience, University of Maryland School of Medicine, 20 Penn Street, Baltimore, MD 21201, USA.

Grants: DA 015718 (Agency:NIDA NIH HHS) ; R01 DA015718-04 (Agency:NIDA NIH HHS) ; T32 DC 00054 (Agency:NIDCD NIH HHS) ; T32 NS 07375 (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-Jun; vol 17 (issue 6) : pp 1342-9

Dates: Created 2007/05/11; Completed 2007/07/03; Revised 2008/11/20;

PMID: 16882682, 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.

Amygdala - cytology; physiology
Animals
Association Learning - physiology
Discrimination Learning - physiology
Electrodes, Implanted
Male
Neurons, Afferent - physiology

Neurons, Afferent - physiology
Odors
Olfactory Bulb - cytology; physiology
Olfactory Pathways - cytology; physiology
Rats
Rats, Long-Evans
Reversal Learning - physiology

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