Visual Cortical Gamma-Band Activity During Free Viewing of Natural Images

N. Brunet, C.A. Bosman, M. Roberts, R. Oostenveld, T. Womelsdorf, P. de Weerd, P. Fries*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Gamma-band activity in visual cortex has been implicated in several cognitive operations, like perceptual grouping and attentional selection. So far, it has been studied primarily under well-controlled visual fixation conditions and using well-controlled stimuli, like isolated bars or patches of grating. If gamma-band activity is to subserve its purported functions outside of the laboratory, it should be present during natural viewing conditions. We recorded neuronal activity with a 252-channel electrocorticographic (ECoG) grid covering large parts of the left hemisphere of 2 macaque monkeys, while they freely viewed natural images. We found that natural viewing led to pronounced gamma-band activity in the visual cortex. In area V1, gamma-band activity during natural viewing showed a clear spectral peak indicative of oscillatory activity between 50 and 80 Hz and was highly significant for each of 65 natural images. Across the ECoG grid, gamma-band activity during natural viewing was present over most of the recorded visual cortex and absent over most remaining cortex. After saccades, the gamma peak frequency slid down to 30-40 Hz at around 80 ms postsaccade, after which the sustained 50- to 80-Hz gamma-band activity resumed. We propose that gamma-band activity plays an important role during natural viewing.
Original languageEnglish
Pages (from-to)918-926
Number of pages9
JournalCerebral Cortex
Issue number4
Early online date9 Oct 2013
Publication statusPublished - Apr 2015

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