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Original Research ARTICLE

Comparing the feature selectivity of the gamma-band of the local field potential and the underlying spiking activity in primate visual cortex

Philipp Berens^1,2, Georgios A. Keliris¹, Alexander S. Ecker^1,2, Nikos K. Logothetis^1,3 and Andreas S. Tolias^1,2*

Max Planck Institute for Biological Cybernetics, Tübingen, Germany

Baylor College of Medicine, Department of Neuroscience, Houston, TX, USA

Division of Imaging Science and Biomedical Engineering, University of Manchester, Manchester, UK

The local field potential (LFP), comprised of low-frequency extra-cellular voltage fluctuations, has been used extensively to study the mechanisms of brain function. In particular, oscillations in the gamma-band (30–90 Hz) are ubiquitous in the cortex of many species during various cognitive processes. Surprisingly little is known about the underlying biophysical processes generating this signal. Here, we examine the relationship of the local field potential to the activity of localized populations of neurons by simultaneously recording spiking activity and LFP from the primary visual cortex (V1) of awake, behaving macaques. The spatial organization of orientation tuning and ocular dominance in this area provides an excellent opportunity to study this question, because orientation tuning is organized at a scale around one order of magnitude finer than the size of ocular dominance columns. While we find a surprisingly weak correlation between the preferred orientation of multi-unit activity and gamma-band LFP recorded on the same tetrode, there is a strong correlation between the ocular preferences of both signals. Given the spatial arrangement of orientation tuning and ocular dominance, this leads us to conclude that the gamma-band of the LFP seems to sample an area considerably larger than orientation columns. Rather, its spatial resolution lies at the scale of ocular dominance columns.

Keywords:

local field potential, primary visual cortex, feature selectivity, macaque, spatial resolution, multi unit activity

Citation:

Berens P, Keliris GA, Ecker AS, Logothetis NK and Tolias AS (2008). Comparing the feature selectivity of the gamma-band of the local field potential and the underlying spiking activity in primate visual cortex. Front. Syst. Neurosci. 2:2. doi: 10.3389/neuro.06.002.2008

Received:

18 April 2008;

Paper pending published:

20 May 2008;

Accepted:

29 May 2008;

Published online:

17 June 2008.

Edited by:

Ranulfo Romo, Universidad Nacional Autónoma de México, Mexico

Reviewed by:

Pascal Fries, Radboud University, The Netherlands
Ranulfo Romo, Universidad Nacional Autónoma de México, Mexico

© 2008 Berens, Keliris, Ecker, Logothetis and Tolias. 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:

Andreas S. Tolias, Baylor College of Medicine, Department of Neuroscience, One Baylor Plaza, Houston, TX 77030, USA. e-mail: atolias@cns.bcm.edu