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New preprint out, where we show that TMS-induced pupil dilations can be used as a measurable proxy of cortical excitability. With: @frasermacrae.bsky.social @freekvanede.bsky.social @daspainbrain.bsky.social @drsmschabrun.bsky.social et al. Details below 🧵 [1/n]

Speculations about the nexus between pupil size and cortical excitability have existed for a while, but evidence for this link is scarce and mainly indirect. We wanted to test it out, by measuring TMS-induced pupil dilations at different TMS intensities and before vs after tDCS inhibition. [2/n]

In three experiments (total n = 59) we found consistent TMS-induced pupil dilations, that peaked approx. 1 s after TMS. We showed this consistent effect in two different isoluminant conditions (300 & 400 lux) and with two different eye-trackers (eyelink & tobii). [3/n]

These TMS-induced dilations were dissociable across TMS intensities and between sham & active TMS. [4/n]

Further, following inhibitory tDCS, we found a decrease in the TMS-induced pupil dilation peaks as compared to baseline, reflecting the anticipated cortical excitability decrease. [5/n]