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

Journal article

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.

Authors: Corthout, E; Hallett, M; Cowey, A

• Publication status: Published
• Journal: Neuroreport
• Volume: 14
• Issue: 4
• Pages: 651-655
• Publication date: 2003-03-01
• DOI: 10.1097/00001756-200303240-00026
• EISSN: 1473-558X
• ISSN: 0959-4965
• Language: English
• Keywords: Choice Behavior; Humans; Brain Mapping; Adult; Photic Stimulation; Visual Perception; Magnetics; Discrimination (Psychology); Male; Functional Laterality; Reaction Time; Electric Stimulation; Occipital Lobe; Female