Tracing the timing of human analysis of motion and chromatic signals from occipital to temporo-parieto-occipital cortex: a transcranial magnetic stimulation study.
In human visual analysis, the initial processing of motion and chromatic signals may be mediated by feed-forward pathways from striate cortex to segregated areas of extrastriate cortex. The time-course of occipital to temporo-parieto-occipital motion processing was unknown, as was the selectivity of the effect of transcranial magnetic stimulation (TMS) on motion processing. TMS delivered over occipital cortex degraded the discrimination of motion-defined form (MDF) in a discrete time window beginning 100-120 ms from the onset of the visual stimulus. Bilateral focal TMS delivered over the temporo-parieto-occipital junction (TPO) disrupted the discrimination of MDF in a time window beginning 20-40 ms later than the effect of TMS delivered over occipital cortex. Bilateral focal TMS delivered over TPO also degraded the discrimination of CDF, motion direction, and color.
Anand
S
S
Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA.
Olson
J D
JD
Hotson
J R
JR
D000293:Adolescent; D000328:Adult; D001921:Brain; D003118:Color Perception; D006801:Humans; D008875:Middle Aged; D009039:Motion Perception; D011601:Psychophysics; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation / Q000009:adverse effects*