期刊
BRAIN AND COGNITION
卷 69, 期 2, 页码 337-343出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.bandc.2008.08.006
关键词
Temporal order judgment; Sensory latency; Right posterior parietal cortex; Transcranial magnetic stimulation
资金
- Korea Research Foundation [KRF-2004-042-H00025]
- Ministry of Science and Technology of the Republic of Korea
Perceived order of two consecutive stimuli may not correspond to the order of their physical onsets. Such a disagreement presumably results from a difference in the speed of stimulus processing toward central decision mechanisms. Since previous evidence suggests that the right posterior parietal cortex (PPC)3 plays a role in modulating the processing speed of a visual target, we applied single-pulse TMS over the region in 14 normal subjects, while they judged the temporal order of two consecutive visual stimuli. Stimulus-onset-asynchrony (SOA) randomly varied between - 100 and 100 ms in 20-ms steps (with a positive SOA when a target appeared on the right hemi-field before the other on the left), and a point of subjective simultaneity was measured for individual subjects. TMS stimulation was time-locked at 50, 100, 150, and 200 ms after the onset of the first Stimulus, and results in trials with TMS on right PPC were compared with those in trials without TMS. TMS over the right PPC delayed the detection of a visual target in the contralatelal, i.e., left hemi-field by 24 (+/-7 SE) ms and 16 (+/-4 SE) ms, when the stimulation was given at 50 and 100 ins after the first target onset. In contrast, TMS on the left PPC was not effective. These results show that the right PPC is important in a timely detection of a target appearing on the left visual field, especially in competition with another target simultaneously appearing in the opposite field. (C) 2008 Elsevier Inc. All rights reserved.
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