Thalamocortical communication is a dynamic process influenced by both presynaptic and postsynaptic mechanisms. In this study, we recorded single-unit responses from cortical neurons that received direct input from the lateral geniculate nucleus (LGN) to address the question of whether prior patterns of cortical activity affect the ability of LGN inputs to drive cortical responses. By examining the ongoing activity that preceded the arrival of electrically evoked spikes from the LGN, we identified a number of activity patterns that were predictive of suprathreshold communication. Namely, cortical neurons were more likely to respond to LGN stimulation when their activity levels increased to 30-40Hz and∕or their activity displayed rhythmic patterns (30 ms intervals) with increased power in the gamma frequency band. Cortical neurons were also more likely to respond to LGN stimulation when their activity increased 30-40 ms prior to stimulation, suggesting that the phase of gamma activity also contributes to geniculocortical communication. Based on these results, we conclude that ongoing activity in the cortex is not random, but rather organized in a manner that can influence the dynamics of thalamocortical communication.
Keywords: V1, LGN, lateral geniculate nucleus, spike rate, coding
Citation: Farran Briggs and W. Martin Usrey (2007). Cortical activity influences geniculocortical spike efficacy in the macaque monkey. Front. Integr. Neurosci. 1:3. doi: 10.3389/neuro.07/003.2007
Received: 31 July 2007;
Paper pending published: 7 September 2007;
Accepted: 30 October 2007; Published online: 30 November 2007.
Edited by:Sidney A. Simon, Duke University Medical Center, USA
Reviewed by:Asif A. Ghazanfar, Princeton University, USA
Copyright: © 2007 Briggs and Usrey. 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: W. Martin Usrey, Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95618, USA. e-mail: firstname.lastname@example.org