Original Research Article
Ensembles of gustatory cortical neurons anticipate and discriminate between tastants in a single lick
Jennifer R. Stapleton 1*, Michael L. Lavine 2, Miguel A.L. Nicolelis 1, 3, 4, 5, 6, 7 and Sidney A. Simon 1, 4, 6
1 Department of Neurobiology, Duke University, USA
2 Institute of Statistics and Decision Sciences, Duke University, USA
3 Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland
4 Department of Biomedical Engineering, USA
5 Department of Psychological and Brain Sciences, USA
6 Center for Neuroengineering, Duke University, USA
7 Edmond and Lily Safra International Institute of Neuroscience of Natal, Brazil
2 Institute of Statistics and Decision Sciences, Duke University, USA
3 Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland
4 Department of Biomedical Engineering, USA
5 Department of Psychological and Brain Sciences, USA
6 Center for Neuroengineering, Duke University, USA
7 Edmond and Lily Safra International Institute of Neuroscience of Natal, Brazil
The gustatory cortex (GC) processes chemosensory and somatosensory information and is involved in learning and anticipation. Previously we found that a subpopulation of GC neurons responded to tastants in a single lick (Stapleton et al., 2006). Here we extend this investigation to determine if small ensembles of GC neurons, obtained while rats received blocks of tastants on a fixed ratio schedule (FR5), can discriminate between tastants and their concentrations after a single 50 μL delivery. In the FR5 schedule subjects received tastants every fifth (reinforced) lick and the intervening licks were unreinforced. The ensemble firing patterns were analyzed with a Bayesian generalized linear model whose parameters included the firing rates and temporal patterns of the spike trains. We found that when both the temporal and rate parameters were included, 12 of 13 ensembles correctly identified single tastant deliveries. We also found that the activity during the unreinforced licks contained signals regarding the identity of the upcoming tastant, which suggests that GC neurons contain anticipatory information about the next tastant delivery. To support this finding we performed experiments in which tastant delivery was randomized within each block and found that the neural activity following the unreinforced licks did not predict the upcoming tastant. Collectively, these results suggest that after a single lick ensembles of GC neurons can discriminate between tastants, that they may utilize both temporal and rate information, and when the tastant delivery is repetitive ensembles contain information about the identity of the upcoming tastant delivery.
Keywords: bayesian generalized linear model, gustatory cortex, neural ensembles, fixed ratio schedule, multi-electrode neurophysiology, rate and temporal coding, gustation, licking
Copyright: © 2007 Stapleton, Lavine, Nicolelis and Simon. This is an open-access article subject to an exclusive license agreement between the authors and the Frontiers Research Foundation, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.
*Correspondence: Jennifer Stapleton, Department of Neurobiology, Duke University, Durham, NC 27710, USA. Tel.: +1 (919) 668–6107. e-mail: stapleton@neuro.duke.edu
Citation: Stapleton JR, Lavine ML, Nicolelis MA and Simon SA (2007) Ensembles of gustatory cortical neurons anticipate and discriminate between tastants in a single lick. Front. Neurosci. 1,1:161-174. doi:10.3389/neuro.01.1.1.012.2007
Received: 15 August 2007; paper pending published: 01 September 2007; accepted: 01 September 2007; published online: 15 October 2007.
Edited by:
Idan Segev, Hebrew University, Israel
Reviewed by:
Federico Bermudez-Rattoni, Universidad Nacional Autónoma de México, Mexico
Marshall Devor, Hebrew University of Jerusalem, Israel
Marshall Devor, Hebrew University of Jerusalem, Israel
*Correspondence: Jennifer Stapleton, Department of Neurobiology, Duke University, Durham, NC 27710, USA. Tel.: +1 (919) 668–6107. e-mail: stapleton@neuro.duke.edu


