PLASTICITY IN VISUOMOTOR COORDINATION AND SPATIAL VISION

点击翻译按钮获取中文摘要

We investigated adaptation in visuomotor coordination and spatial vision following long-term exposure to left-right reversed vision in human and monkey.For the human study, we conducted an experiment each year in each of which several participants wore left-right reversing spectacles continuously for 37 days. During the experiment, the participants were repeatedly tested with various perceptual and perceptual-motor tasks in cognitive psychological and neuroscientific methodologies. The results were as follows. (1) Position constancy a phenomenon that the visual field does not appear to oscillate even when one moves his/her head, was lost at the onset of reversed vision, but the perceptual oscillation gradually diminished and disappeared in 10 days (by magnitude estimation) or 20 days (by comparing left-right with up-down head movements) of wearing spectacles. (2) Reaching task performance was restored in 10 days of wearing. (3) Brain activation of the primary visual cortex (V1) for hem … More i visual field stimulation was measured by fMRI (functional Magnetic Resonance Imaging), and it was observed that seven out of ten participants showed an adaptive change from contra-lateral to bilateral activation of V1. The timing of the emergence of the bilateral activation was at 3 to 7 weeks of wearing, which suggests, together with behavioral results, that each participant went through visual-somatic reorganization before the adaptive change. Activation spreading to ipsilateral V2 was also observed in the course of adaptation.The monkey study was to see differences in adaptation process and its endpoints between adults and children. Two monkeys aged six months wore left-right reversing spectacles continuously. Adults (human or monkey) are greatly puzzled by the onset of the reversed vision, and, as a result, their behavioral activity is decreased. In contrast, the child monkeys showed no such bewildered behaviors and were quite active at the onset of the reversed vision. Such a contrast between adults and children was to be noted for further research. Less