Slow phasic and tonic activity of ventral pallidal neurons during cocaine self-administration
Article first published online: 3 NOV 2011
Copyright © 2011 Wiley Periodicals, Inc.
Volume 66, Issue 2, pages 106–127, February 2012
How to Cite
Root, D. H., Fabbricatore, A. T., Pawlak, A. P., Barker, D. J., Ma, S. and West, M. O. (2012), Slow phasic and tonic activity of ventral pallidal neurons during cocaine self-administration. Synapse, 66: 106–127. doi: 10.1002/syn.20990
- Issue published online: 7 DEC 2011
- Article first published online: 3 NOV 2011
- Accepted manuscript online: 27 SEP 2011 07:35PM EST
- Manuscript Accepted: 14 SEP 2011
- Manuscript Received: 10 MAR 2011
- National Institute on Drug Abuse Grants. Grant Numbers: DA 006886, DA 026252
- National Institute of Mental Health Grant. Grant Number: MH 0919957
Ventral pallidal (VP) neurons exhibit rapid phasic firing patterns within seconds of cocaine-reinforced responses. The present investigation examined whether VP neurons exhibited firing rate changes: (1) over minutes during the inter-infusion interval (slow phasic patterns) and/or (2) over the course of the several-hour self-administration session (tonic firing patterns) relative to pre-session firing. Approximately three-quarters (43/54) of VP neurons exhibited slow phasic firing patterns. The most common pattern was a post-infusion decrease in firing followed by a progressive reversal of firing over minutes (51.16%; 22/43). Early reversals were predominantly observed anteriorly whereas progressive and late reversals were observed more posteriorly. Approximately half (51.85%; 28/54) of the neurons exhibited tonic firing patterns consisting of at least a two-fold change in firing. Most cells decreased firing during drug loading, remained low over self-administration maintenance, and reversed following lever removal. Over a whole experiment (tonic) timescale, the majority of neurons exhibited an inverse relationship between calculated drug level and firing rates during loading and post-self-administration behaviors. Fewer neurons exhibited an inverse relationship of calculated drug level and tonic firing rate during self-administration maintenance but, among those that did, nearly all were progressive reversal neurons. The present results show that, similar to its main afferent the nucleus accumbens, VP exhibits both slow phasic and tonic firing patterns during cocaine self-administration. Given that VP neurons are principally GABAergic, the predominant slow phasic decrease and tonic decrease firing patterns within the VP may indicate a disinhibitory influence upon its thalamocortical, mesolimbic, and nigrostriatal targets during cocaine self-administration. Synapse, 2012. © 2011 Wiley Periodicals, Inc.