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Theta oscillations in rat infralimbic cortex are associated with the inhibition of cocaine seeking during extinction
Journal article   Open access   Peer reviewed

Theta oscillations in rat infralimbic cortex are associated with the inhibition of cocaine seeking during extinction

Victória A Müller Ewald, Jangjin Kim, Sean J Farley, John H Freeman and Ryan T LaLumiere
Addiction biology, Vol.27(1), pp.e13106-e13106
10/20/2021
DOI: 10.1111/adb.13106
PMCID: PMC8922975
PMID: 34672059
url
https://doi.org/10.1111/adb.13106View
Published (Version of record) Open Access

Abstract

Infralimbic cortical (IL) manipulations indicate that this region mediates extinction learning and suppresses cocaine seeking following cocaine self-administration. However, little work has recorded IL activity during the inhibition of cocaine seeking due to the difficulty of determining precisely when cocaine-seeking behaviour is inhibited within a cocaine-seeking session. The present study used in vivo electrophysiology to examine IL activity across extinction as well as during cocaine self-administration and reinstatement. Sprague–Dawley rats underwent 6-h access cocaine self-administration in which the response lever was available during discrete signalled trials, a procedure which allowed for the comparison between epochs of cocaine seeking versus the inhibition thereof. Subsequently, rats underwent extinction and cocaine-primed reinstatement using the same procedure. Results indicate that theta rhythms (4–10 Hz) dominated IL local-field potential (LFP) activity during all experimental stages. During extinction, theta power fluctuated significantly surrounding the lever press and was lower when rats engaged in cocaine seeking versus when they withheld from doing so. These patterns of oscillatory activity differed from self-administration and reinstatement stages. Single-unit analyses indicate heterogeneity of IL unit responses, supporting the idea that multiple neuronal subpopulations exist within the IL and promote the expression of different and even opposing cocaine-seeking behaviours. Together, these results are consistent with the idea that aggregate synaptic and single-unit activity in the IL represent the engagement of the IL in action monitoring to promote adaptive behaviour in accordance with task contingencies and reveal critical insights into the relationship between IL activity and the inhibition of cocaine seeking.

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