Spear P D, Tong L, McCall M A
Department of Psychology and Neurosciences Training Program, University of Wisconsin, Madison 53706.
Brain Res. 1988 Apr 26;447(1):79-91. doi: 10.1016/0006-8993(88)90967-5.
The aim of the present study was to investigate the mechanisms of physiological compensation that is seen in the posteromedial lateral suprasylvian (PMLS) cortex of cats that received visual cortex (areas 17, 18, and 19) damage early in life. The strategy was to compare the response properties of PMLS neurons just after visual cortex damage (before any compensation has occurred) with the properties of PMLS neurons in normal cats and cats with long-standing visual cortex damage. Fourteen animals (aged 8 weeks, 18 weeks, 26 weeks, or adult) received a unilateral visual cortex lesion and recordings were made from ipsilateral PMLS cortex within about 24 h. An additional 4 adult cats were studied within either 24 or 3 h of a bilateral visual cortex lesion. Results from these animals were compared with results from normal cats and cats with long-standing visual cortex damage studied previously in this laboratory. At all ages studied, an acute visual cortex lesion reduced the percentage of direction-sensitive cells in PMLS cortex from nearly 80% in normal cats to about 20% after the lesion. In 8- and 18-week-old kittens, nearly all of the remaining PMLS cells responded best to stimulus movement but were not direction sensitive. In 26-week-old and adult cats, the remaining cells were divided between those that responded to movement without a directional preference and those that responded as well to stationary flashed stimuli as to moving stimuli. The presence of receptive-field surround inhibition was not affected significantly by an acute lesion at any age. In addition, few PMLS cells were orientation selective to elongated slits of light in cats with an acute lesion, just as in normal cats. The ocular dominance distributions of PMLS neurons also were normal following an acute visual cortex lesion at all ages studied. These results suggest that the influences of areas 17, 18, and 19 on the response properties of PMLS neurons are the same when the properties first reach maturity as in adult cats. The results also suggest that the mechanisms of physiological compensation for an early visual cortex lesion differ for different response properties. Compensation of direction sensitivity and orientation selectivity (an anomalous property) develops de novo after the early lesion. In contrast, compensation of ocular dominance appears to be due to the maintenance of a preexisting property that is present immediately after the lesion. Thus, plasticity after early visual cortex damage represents multiple developmental changes in the remaining visual pathways.
本研究的目的是探究早期生活中接受视觉皮层（17、18和19区）损伤的猫，其大脑后内侧上薛氏回（PMLS）皮层出现生理补偿的机制。研究策略是比较视觉皮层损伤后即刻（在任何补偿发生之前）PMLS神经元的反应特性，与正常猫以及长期存在视觉皮层损伤的猫的PMLS神经元特性。14只动物（年龄分别为8周、18周、26周或成年）接受单侧视觉皮层损伤，并在约24小时内从同侧PMLS皮层进行记录。另外4只成年猫在双侧视觉皮层损伤后的24小时内或3小时内接受研究。将这些动物的结果与本实验室之前研究的正常猫以及长期存在视觉皮层损伤的猫的结果进行比较。在所有研究的年龄阶段，急性视觉皮层损伤使PMLS皮层中方向敏感细胞的百分比从正常猫的近80%降至损伤后的约20%。在8周和18周龄的小猫中，几乎所有剩余的PMLS细胞对刺激运动反应最佳，但不具有方向敏感性。在26周龄和成年猫中，剩余的细胞分为两类，一类对运动无方向偏好，另一类对静止闪烁刺激和运动刺激的反应相同。在任何年龄，急性损伤对感受野周围抑制的存在均无显著影响。此外，与正常猫一样，急性损伤的猫中很少有PMLS细胞对细长光缝具有方向选择性。在所有研究的年龄阶段，急性视觉皮层损伤后PMLS神经元的眼优势分布也正常。这些结果表明，当17、18和19区的特性首次成熟时，它们对PMLS神经元反应特性的影响与成年猫相同。结果还表明，早期视觉皮层损伤的生理补偿机制因不同的反应特性而异。方向敏感性和方向选择性（一种异常特性）的补偿在早期损伤后重新发展。相比之下，眼优势的补偿似乎是由于损伤后立即存在的预先存在的特性得以维持。因此，早期视觉皮层损伤后的可塑性代表了剩余视觉通路中的多种发育变化。
