Biomedical subjects

Erik Corthout

Publications and source records attributed to Erik Corthout.

2 recordsLinked to original sources

PubMed2003

Interference with vision by TMS over the occipital pole: a fourth period.

We investigated the effect of single-pulse transcranial magnetic stimulation (TMS) over the occipital pole on a forced-choice visual letter-identification task. Magnetic stimuli were applied on the midline but with the initial current directed pseudorandomly toward either left or right hemisphere; visual stimuli were presented randomly in either left or right hemifield; magnetic-visual stimulus onset asynchrony varied randomly between 12 values: -500 ms and from -50 ms to +50 ms in 10 ms steps. The data revealed the existence of a hitherto unknown fourth task-interfering TMS effect that was maximal at -10 ms and specific for magnetic stimulus polarity and visual stimulus location. This -10 ms effect cannot be explained by reflex blinking (as the -50 ms effect can) and direct disruption of letter-induced activity (as the +20 ms and +100 ms effects can), but it could be explained by direct disruption of pre-letter activity or indirect disruption of letter-induced activity.

Adult↗

PubMed2002

Early visual cortical processing suggested by transcranial magnetic stimulation.

Single-pulse transcranial magnetic stimulation (TMS) was applied to the occipital pole of healthy subjects while they performed a forced-choice visual letter-identification task. Pulses were applied on the midline but with a left-right asymmetric polarity; pulse application occurred at a variable delay after letter presentation onset; letters were presented in left or right hemifield. Averaging data over subjects and hemifields showed that performance attained local minima at 20 ms and 100 ms; averaging data over subjects and delays showed that performance was biased towards the same hemifield during both delay intervals; averaging data over subjects showed that the hemifield bias progressively decreased from 20 ms to 50 ms. The data are consistent with the possibility that also the earlier delay interval reflects visual cortical processing.

Adult↗