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Under natural conditions, the visual system often sees a given input repeatedly. This provides an opportunity to optimize processing of the repeated stimuli. Stimulus repetition has been shown to strongly modulate neuronal-gamma band synchronization, yet crucial questions remained open. Here we used magnetoencephalography in 30 human subjects and find that gamma decreases across ~10 repetitions and then increases across further repetitions, revealing plastic changes of the activated neuronal circuits. Crucially, changes induced by one stimulus did not affect responses to other stimuli, demonstrating stimulus specificity. Changes partially persisted when the inducing stimulus was repeated after 25 minutes of intervening stimuli. They were strongest in early visual cortex and increased interareal feedforward influences. Our results suggest that early visual cortex gamma synchronization enables adaptive neuronal processing of recurring stimuli. These and previously reported changes might be due to an interaction of oscillatory dynamics with established synaptic plasticity mechanisms.
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This MEG pupillometry study investigated the stimulus-specific plasticity in human visual gamma-band activity. The results show that both Gamma-band MEG and pupil size responses to visual stimuli adapt across stimulus repetitions. This work will be of broad interest to readers in the fields of non-human primate and human electrophysiology. The claims are fully supported by the data but the links between behavior, pupil size and MEG signals could be investigated further.
(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #2 agreed to share their name with the authors.)
Reviewer #1 (Public Review):
This study investigated the stimulus-specific plasticity in human visual gamma-band activity using MEG. The study found that stimulus repetition modulated gamma band activity. Gamma-band responses decreased across~10 repetitions and then increased across further repetitions. These effects were strongest in early visual cortex and increased interareal feedforward influences. The study was nicely performed and grounded well with the previous literature. Albeit the analysis were performed were state-of-the art, there were quite many unclear issues in the data-analysis, some of which are critical for the interpretation of the results.
Reviewer #2 (Public Review):
Stauch et al linked stimulus-repetition induced changes in behavior, MEG Gamma-band responses, and pupil size. This work is conducted thoroughly, and exhibits a high degree of technical proficiency. The results speak to repetition suppression, sensory adaptation, and the flexibility of neural coding in general. The promise of the present project lies in the combination of measurement modalities in one project, which they do using a regression model approach. The patterns in the data confirm a host of different extant studies' findings, and provide a self-consistent vista on the phenomenon of interest.