Summary: LFP Power Spectra in V1 Cortex: The Graded Effect of Stimulus Contrast
J. Andrew Henrie and Robert Shapley
Center for Neural Science, New York University, New York, New York
Submitted 3 September 2004; accepted in final form 7 February 2005
Henrie, J. Andrew and Robert Shapley. LFP power spectra in V1 cortex:
the graded effect of stimulus contrast. J Neurophysiol 94: 479­490, 2005.
First published February 9, 2005; doi:10.1152/jn.00919.2004. We
recorded local field potentials (LFPs) and single-unit activity simul-
taneously in the macaque primary visual cortex (V1) and studied their
responses to drifting sinusoidal gratings that were chosen to be
"optimal" for the single units. Over all stimulus conditions, the LFP
spectra have much greater power in the low-frequency band ( 10 Hz)
than higher frequencies and can be described as "1/f." Analysis of the
total power limited to the low, gamma (25­90 Hz), or broad (8­240
Hz) frequency bands of the LFP as a function of stimulus contrast
indicates that the LFP power gradually increases with stimulus
strength across a wide band in a manner roughly comparable to the
increase in the simultaneously recorded spike activity. However, the
low-frequency band power remains approximately constant across all
stimulus contrasts. More specifically the gamma-band LFP power

Source: Andrzejak, Ralph Gregor - Departament de Tecnologia, Universitat Pompeu Fabra
Mohri, Mehryar - Computer Science Department, Courant Institute of Mathematical Sciences, New York University

Collections: Computer Technologies and Information Sciences