Seeing in the dark: Phosphene thresholds with eyes open versus closed in the absence of visual inputs

Brain Stimulation
T A de GraafA T Sack

Abstract

Voluntarily opening or closing our eyes results in fundamentally different input patterns and expectancies. Yet it remains unclear how our brains and visual systems adapt to these ocular states. We here used transcranial magnetic stimulation (TMS) to probe the excitability of the human visual system with eyes open or closed, in the complete absence of visual inputs. Combining Bayesian staircase procedures with computer control of TMS pulse intensity allowed interleaved determination of phosphene thresholds (PT) in both conditions. We measured parieto-occipital EEG baseline activity in several stages to track oscillatory power in the alpha (8-12 Hz) frequency-band, which has previously been shown to be inversely related to phosphene perception. Since closing the eyes generally increases alpha power, one might have expected a decrease in excitability (higher PT). While we confirmed a rise in alpha power with eyes closed, visual excitability was actually increased (PT was lower) with eyes closed. This suggests that, aside from oscillatory alpha power, additional neuronal mechanisms influence the excitability of early visual cortex. One of these may involve a more internally oriented mode of brain operation, engaged by closing the ...Continue Reading

Citations

Apr 24, 2019·Journal of Cognitive Neuroscience·Tahnée EngelenAlexander T Sack
Jan 17, 2020·The European Journal of Neuroscience·Tom A de GraafAlexander T Sack
Jan 9, 2019·Frontiers in Neuroscience·Tom A de GraafAlexander T Sack
May 12, 2019·Brain Topography·Agnese ZazioDomenica Veniero
Mar 26, 2021·Clinical Neurophysiology : Official Journal of the International Federation of Clinical Neurophysiology·Mohd Faizal Mohd ZulkiflyWalter Paulus
Aug 15, 2018·Neuropsychologia·Florian HerpichLorella Battelli
Jun 16, 2021·Scientific Reports·Maria J S GuerreiroBrigitte Röder
Oct 14, 2021·Scientific Reports·Takaaki KomiyamaSatoshi Shimegi

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