演題番号 : P3-h04
加藤 利佳子 / Rikako Kato:1 高浦 加奈 / Kana Takaura:1,2 池田 琢朗 / Takuro Ikeda:1 吉田 正俊 / Masatoshi Yoshida:1,2 伊佐 正 / Tadashi Isa:1,2
1:生理学研究所 認知行動発達機構研究部門 / Dept of Dev. Physiol. Nat'l Inst. Physiol. Sci., Okazaki, Japan 2:総合研究大学院大学 / The Graduate Univ. for Advanced Studies, Hayama, Japan
The primary visual cortex (V1) is the main gateway to the cerebral cortex for visual information processing and the damage to V1 is known to cause loss of visual awareness. However, previous studies demonstrated that some patients and monkeys with V1 lesions could locate visual targets with hand or eye movements. After V1 lesion, the retinotectal pathway and the pathway via the LGN to the extrastriate cortex are supposed to compensate for absence of pathway via V1. In this study, to examine the role of retinotectal pathway in the visuo-motor processing for the control of saccadic eye movements, we inactivated the superior colliculus (SC) of the monkeys (n=2) with unilateral V1 lesion and analyzed the effect on visually guided saccades. Experiments were made after the recovery of their performance. Injection dose of muscimol was adjusted to the range causing the moderate motor deficits of visually guided saccades in normal monkeys. The target was presented randomly in one of eight possible locations arranged radially with the same intervals (45 deg). One location was set at the topographical representation of the injection site.After injections to the contralesional SC, the monkeys could make saccades to the target toward the spatial representation of the injection site. We observed only minor deficits, such as the effects to amplitudes and latencies. In contrast, after injections to the ipsilesional SC, the monkeys could not make a saccade to the target encoded by the injection site. Most saccades ended at the points with over 45 deg of directional error beyond neighboring targets. The monkeys occasionally ignored the target and kept their eye at the fixation point during the period of target presentation. The effects of ipsilesional SC inactivation were much more severe. Our study demonstrated that the visual processing via the retino-tectal pathway plays an essential role in the control of visually guided saccade after the V1 lesion.