Gruberg E R, Wallace M T, Caine H S, Mote M I
Biology Department, Temple University, Philadelphia, Pa.
Brain Behav Evol. 1991;37(2):92-103. doi: 10.1159/000114350.
Unilateral lesions of the nucleus isthmi result in a scotoma to visually presented prey and threat stimuli in the contralateral monocular visual field. There is a correlation between the size of the scotoma and the amount of n. isthmi ablated. Following the lesion, there is a regression of the scotoma in the nasal part of the visual field which then stabilizes. Upon longer behavioral examination, the animals can be divided into two classes: (1) animals in which the scotoma remains relatively stable in size for up to two years, and (2) animals which recover from the scotoma. In the latter group, there tends to be damage to both the n. isthmi and the posterodorsal tegmental nucleus which lies mediocaudal to the n. isthmi. Electrophysiological recording from positions within the area of the optic tectum representing the scotoma reveal an average threefold increase in the size of the multiunit receptive fields compared to mirror image positions in the contralateral optic tectum.
峡核单侧损伤会导致对侧单眼视野中视觉呈现的猎物和威胁刺激出现暗点。暗点大小与被切除的峡核数量之间存在相关性。损伤后，视野鼻侧部分的暗点会逐渐消退，然后趋于稳定。经过更长时间的行为学检查，动物可分为两类：（1）暗点大小在长达两年的时间内保持相对稳定的动物；（2）暗点恢复的动物。在后一组中，峡核和位于峡核中尾内侧的后背部被盖核往往都有损伤。在代表暗点的视顶盖区域内进行电生理记录发现，与对侧视顶盖中的镜像位置相比，多单位感受野的大小平均增加了三倍。
