抄録
During target-reaching movements, humans can make mid-flight adjustments (switching) when the target jumps to new positions. To examine if the primary visual cortex is involved in the adjustment, we have established a method to suppress the visual cortex during the movement. Three normal human subjects, who gave informed consents, participated in experiments. They sat ca. 40 cm in front of a CRT monitor, with their chin supported by a chin rest. A figure-of-eight coil for transcranial magnetic stimulation (TMS) was held over the primary visual cortex as described previously (Kammer et al., 2005), whose position was checked on MRI brain images from each subject (Navigation System, NexStim). When subjects gazed at a 1 cm square target in the center of the screen, sound GO signal was given to reach to the target. After 25 ms from the movement onset, the center target sometimes disappeared, and a new target could appear either transiently (duration<10 ms) or constantly. It appeared 10 cm left or right to, and 2 cm below the central target. TMS was sometimes delivered over the visual cortex 70 or 100 ms after appearance of the new target. Subjects were instructed to reach the new target, and their arm positions were monitored by Optotrak system (NDI). After each trial, subjects reported if and where they saw a new target. In two of the subjects, we succeeded to suppress visual perception during reaching, without disturbing the movement. We further analyzed suppression effects on the arm movement. [J Physiol Sci. 2008;58 Suppl:S193]
