Gahery Y, Towe A L
Unite de Neurosciences Integratives, Centre National de la Recherche Scientifique, Marseille, France.
Exp Brain Res. 1993;94(2):273-8. doi: 10.1007/BF00230296.
The distribution of optic chiasm input to different types of neurons in pericruciate cortex of cats agreed with previous work using light flashes. Neuron response times served to differentiate the input pathways to pericruciate cortex, and the types of neurons they influence. Input from the optic chiasm arrived in three distinct surges: the first via the superior colliculus, the second via an unidentified pathway, and the third via the visual cortex. A fourth, diffuse surge arrived in the postcruciate cortex via some unidentified pathway. Stimulation of the contralateral side of the optic chiasm had a weaker effect than stimulation of the ipsilateral side; it evoked activity at a higher threshold, with fewer spikes per response, and at a longer latency. The difference in response latency between the two sides was largest on neurons responding to the first surge, decreasing in later surges, and being least on those neurons responding to the last surge. About 2.3% of the postcruciate and 15% of the precruciate neurons responded only to optic chiasm stimulation; they were isolated in the granular layers, and their responses could not be influenced by prior cutaneous input. It is suggested that much of the visual input to pericruciate cortex serves to modulate on-going cortical output and, thereby, the behavior of the animal.
猫十字沟周围皮层中不同类型神经元的视交叉输入分布与先前使用闪光的研究结果一致。神经元反应时间有助于区分到十字沟周围皮层的输入通路以及它们所影响的神经元类型。来自视交叉的输入以三种不同的波峰形式到达：第一个通过上丘，第二个通过一条未明确的通路，第三个通过视觉皮层。第四个弥散波峰通过一些未明确的通路到达十字沟后皮层。对视交叉对侧的刺激比同侧刺激的效果弱；它在更高的阈值下诱发活动，每次反应的尖峰数量更少，潜伏期更长。两侧反应潜伏期的差异在对第一个波峰有反应的神经元上最大，在随后的波峰中减小，在对最后一个波峰有反应的神经元上最小。约2.3%的十字沟后神经元和15%的十字沟前神经元仅对视交叉刺激有反应；它们孤立于颗粒层，其反应不受先前皮肤输入的影响。有人提出，到十字沟周围皮层的大部分视觉输入用于调节正在进行的皮层输出，从而调节动物的行为。
