Areas V1 and V2 show microsaccade-related 3-4-Hz covariation in gamma power and frequency

Eur J Neurosci. 2016 May;43(10):1286-96. doi: 10.1111/ejn.13126. Epub 2015 Dec 16.


Neuronal gamma-band synchronization (25-80 Hz) in visual cortex appears sustained and stable during prolonged visual stimulation when investigated with conventional averages across trials. However, recent studies in macaque visual cortex have used single-trial analyses to show that both power and frequency of gamma oscillations exhibit substantial moment-by-moment variation. This has raised the question of whether these apparently random variations might limit the functional role of gamma-band synchronization for neural processing. Here, we studied the moment-by-moment variation in gamma oscillation power and frequency, as well as inter-areal gamma synchronization, by simultaneously recording local field potentials in V1 and V2 of two macaque monkeys. We additionally analyzed electrocorticographic V1 data from a third monkey. Our analyses confirm that gamma-band synchronization is not stationary and sustained but undergoes moment-by-moment variations in power and frequency. However, those variations are neither random and nor a possible obstacle to neural communication. Instead, the gamma power and frequency variations are highly structured, shared between areas and shaped by a microsaccade-related 3-4-Hz theta rhythm. Our findings provide experimental support for the suggestion that cross-frequency coupling might structure and facilitate the information flow between brain regions.

Keywords: electrophysiology; gamma-band response; monkey; saccade; visual system.

MeSH terms

  • Animals
  • Cortical Synchronization*
  • Gamma Rhythm*
  • Macaca mulatta
  • Male
  • Neural Pathways / physiology
  • Photic Stimulation
  • Saccades*
  • Signal Processing, Computer-Assisted
  • Theta Rhythm*
  • Visual Cortex / physiology*