Strong N P, Malach R, Lee P, Van Sluyters R C
Brain Res. 1984 Apr;315(2):179-92. doi: 10.1016/0165-3806(84)90153-6.
We have examined recovery from the acute effects of unilateral and bilateral visual cortex lesions on horizontal optokinetic nystagmus (OKN) in the cat. A single bilateral cortical lesion virtually abolishes monocular OKN in response to temporalward stimulation, and severely reduces OKN in response to nasalward stimulation at higher drum velocities. A unilateral cortical lesion causes deficits in OKN toward the side of the lesion, but these changes are less substantial than those observed after a bilateral lesion. The nature of the acute changes in OKN caused by cortical lesions supports the notion that the visual cortex has two important roles in the OKN system of the cat: first, it mediates OKN in response to temporalward motion of the visual environment during monocular viewing; second, it expands the response range of the OKN system to include higher stimulus velocities. Finally, the results from unilaterally lesioned cats suggest that a single hemisphere can mediate OKN in both directions, with an emphasis on the direction ipsilateral to that hemisphere. The patterns of recovery of OKN in lesioned cats follow two major trends: a small, gradual increase in the overall gain of OKN from its severely depressed level immediately after a large bilateral lesion, and a 'balancing' process that reduces the marked asymmetry between rightward and leftward OKN caused by a unilateral lesion. This balancing of the reflex is accomplished by an improvement in performance in one direction while performance in the opposite direction actually declines. Recovery is faster and more pronounced in lesioned cats with one cortical hemisphere intact, suggesting that the surviving visual cortex compensates for the effects of the lesion by modifying activity in subcortical pathways. These experiments indicate that the visual system of the cat has the capacity to recover at least partially from the deficits in OKN behavior caused by cortical lesions, and that this recovery is the outcome of an interaction between cortical and subcortical pathways mediating this important visuomotor reflex.
我们研究了猫单侧和双侧视觉皮层损伤对水平视动性眼震（OKN）急性影响的恢复情况。单个双侧皮层损伤实际上消除了对颞侧刺激的单眼OKN，并在较高鼓速下严重降低了对鼻侧刺激的OKN。单侧皮层损伤会导致损伤侧的OKN出现缺陷，但这些变化不如双侧损伤后观察到的那么明显。皮层损伤引起的OKN急性变化的性质支持这样一种观点，即视觉皮层在猫的OKN系统中具有两个重要作用：第一，它在单眼观察期间介导对视觉环境颞侧运动的OKN；第二，它扩大了OKN系统的反应范围，以包括更高的刺激速度。最后，单侧损伤猫的结果表明，单个半球可以介导两个方向的OKN，重点是该半球同侧的方向。损伤猫中OKN的恢复模式遵循两个主要趋势：在大的双侧损伤后，OKN的总体增益从严重降低的水平逐渐小幅增加，以及一个“平衡”过程，该过程减少了单侧损伤引起的向右和向左OKN之间的明显不对称。这种反射的平衡是通过一个方向的性能改善而相反方向的性能实际上下降来实现的。在一个皮层半球完整的损伤猫中，恢复更快且更明显，这表明存活的视觉皮层通过改变皮层下通路的活动来补偿损伤的影响。这些实验表明，猫的视觉系统有能力至少部分地从皮层损伤引起的OKN行为缺陷中恢复，并且这种恢复是介导这种重要视运动反射的皮层和皮层下通路之间相互作用的结果。
