LFP power spectra in V1 cortex: The graded effect of stimulus contrast

J. Andrew Henrie, Robert Shapley

Research output: Contribution to journalArticlepeer-review


We recorded local field potentials (LFPs) and single-unit activity simultaneously 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 "l/f." Analysis of the total power limited to the low, gamma (25-90 Hz), or broad (8-240 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 increases differentially more with respect to baseline than either higher or lower bands as stimulus contrast increases. At the highest stimulus contrasts, we report as others have previously, that the power spectrum of the LFP typically contains an obvious peak in the gamma-frequency band. The gamma-band peak emerges from the overall broadband enhancement in LFP power at stimulus contrasts where most single units' responses have begun to saturate. The temporal/spectral structures of the LFP located in the gamma band-which become most evident at the highest contrasts-provide additional constraints on potential mechanisms underlying the stimulus response properties of spiking neurons in V1.

Original languageEnglish (US)
Pages (from-to)479-490
Number of pages12
JournalJournal of neurophysiology
Issue number1
StatePublished - Jul 2005

ASJC Scopus subject areas

  • General Neuroscience
  • Physiology


Dive into the research topics of 'LFP power spectra in V1 cortex: The graded effect of stimulus contrast'. Together they form a unique fingerprint.

Cite this