急性毁损猫的初级视区使高级视区细胞失去对视觉刺激的诱发反应

摘要

心理物理学研究提示,初级视区毁损后的视觉残留可能是通过外纹状皮层的神经网络重组介导的,但缺少支持这一假说的电生理实验证据.采用在体细胞外单细胞记录技术,该研究分别检测了初级视区(主要包括17和18区)急性毁损猫和正常对照猫的高级视区(包括19、20和21区)神经元对不同视觉刺激的反应性.结果显示,与对照相比,急性毁损初级视区使99.3％的高级视区神经元丧失对运动光栅刺激的诱发反应,93％的神经元丧失对闪光刺激的反应.该结果表明,急性毁损成年猫的初级视皮层可能会导致其绝大部分视觉能力丧失.在幼年期实施初级视皮层毁损后,成年猫出现的残留视觉可能主要是由于手术后皮层下神经核团与外纹状皮层之间的通路重组引起的.%Psychophysical studies suggest that lateral extrastriate visual cortical areas in cats may mediate the sparing of vision largely by network reorganization following lesions of early visual cortical areas.To date,however,there is little direct physiological evidence to support this hypothesis.Using in vivo single-unit recording techniques,we examined the response of neurons in areas 19,21,and 20 to different types of visual stimulation in cats with or without acute bilateral lesions in areas 17 and 18.Our results showed that,relative to the controls,acute lesions inactivated the response of 99.3％ of neurons to moving gratings and 93％ of neurons to flickering square stimuli in areas 19,21,and 20.These results indicated that acute lesions of primary visual areas in adult cats may impair most visual abilities.Sparing of vision in cats with neonatal lesions in early visual cortical areas may result largely from a postoperative reorganization of visual pathways from subcortical nucleus to extrastriate visual cortical areas.