Huxlin Krystel R, Pasternak Tatiana
Department of Ophthalmology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA.
Cereb Cortex. 2004 Jan;14(1):81-90. doi: 10.1093/cercor/bhg106.
Unilateral ibotenic acid lesions of the lateral suprasylvian (LS) cortex severely impair the ability of cats to integrate local motion signals (measured as direction range thresholds) and to extract motion signals from noise (measured as motion signal thresholds) in their contra-lesional visual hemifields. These deficits were found up to several months after the lesions and were limited to thresholds measured with random-dot stimuli, while contrast sensitivity for discriminating the direction of motion of sine-wave gratings remained unaffected. Our goal was to determine whether deficits of complex motion perception could recover and whether the recovery was spontaneous or required retraining. In each cat, a single location in the impaired visual hemifield was selected for visual retraining, which required the animals to discriminate motion direction using random-dot stimuli in which the range of dot directions was varied. Fifteen to 40 days of intensive retraining led to a gradual, complete recovery of motion integration. The recovery was stimulus specific since it did not transfer from direction range to motion signal thresholds, and it was largely restricted to the visual field locations retrained. Delaying the onset of retraining by several days to several months had no significant impact on the extent or rate of recovery. Once recovery was achieved, performance remained stable over a period of several months. These results suggest that recovery of complex visual motion perception after lesions of extrastriate visual cortex is an active process that requires extensive, stimulus- and retinotopically-specific visual retraining.
外侧上薛氏（LS）皮质的单侧鹅膏蕈氨酸损伤严重损害了猫在其患侧视觉半视野中整合局部运动信号（以方向范围阈值衡量）以及从噪声中提取运动信号（以运动信号阈值衡量）的能力。这些缺陷在损伤后长达数月都能被发现，并且仅限于用随机点刺激测量的阈值，而用于辨别正弦波光栅运动方向的对比敏感度仍未受影响。我们的目标是确定复杂运动感知的缺陷是否能够恢复，以及这种恢复是自发的还是需要重新训练。在每只猫中，选择受损视觉半视野中的一个单一位置进行视觉再训练，这要求动物使用点方向范围变化的随机点刺激来辨别运动方向。15至40天的强化再训练导致运动整合逐渐完全恢复。这种恢复是刺激特异性的，因为它不会从方向范围转移到运动信号阈值，并且很大程度上局限于接受再训练的视野位置。将再训练开始时间推迟数天至数月对恢复程度或恢复速度没有显著影响。一旦实现恢复，在数月时间内表现保持稳定。这些结果表明，纹外视觉皮质损伤后复杂视觉运动感知的恢复是一个主动过程，需要广泛的、刺激特异性和视网膜拓扑特异性的视觉再训练。
