Differences in gamma frequencies across visual cortex restrict their possible use in computation

Neuron. 2010 Sep 9;67(5):885-96. doi: 10.1016/j.neuron.2010.08.004.


Neuronal oscillations in the gamma band (30-80 Hz) have been suggested to play a central role in feature binding or establishing channels for neural communication. For these functions, the gamma rhythm frequency must be consistent across neural assemblies encoding the features of a stimulus. Here we test the dependence of gamma frequency on stimulus contrast in V1 cortex of awake behaving macaques and show that gamma frequency increases monotonically with contrast. Changes in stimulus contrast over time leads to a reliable gamma frequency modulation on a fast timescale. Further, large stimuli whose contrast varies across space generate gamma rhythms at significantly different frequencies in simultaneously recorded neuronal assemblies separated by as little as 400 microm, making the gamma rhythm a poor candidate for binding or communication, at least in V1. Instead, our results suggest that the gamma rhythm arises from local interactions between excitation and inhibition.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Brain Mapping*
  • Contrast Sensitivity / physiology
  • Electroencephalography*
  • Entropy
  • Evoked Potentials, Visual / physiology*
  • Eye Movements / physiology
  • Macaca mulatta
  • Male
  • Neurons / physiology*
  • Numerical Analysis, Computer-Assisted*
  • Pattern Recognition, Visual / physiology
  • Photic Stimulation / methods
  • Time Factors
  • Visual Cortex / cytology
  • Visual Cortex / physiology*
  • Visual Pathways / physiology
  • Wakefulness