Ilg U J
Sektion für Visuelle Sensomotorik, Neurologische Universitätsklinik, Tübingen, Germany.
Exp Brain Res. 1997 Feb;113(2):361-4. doi: 10.1007/BF02450334.
The directional selectivity of the visual response properties was determined in 148 neurons, all located in area MT of three hemispheres of two macaque monkeys. The preferred direction of every neuron was obtained by analyzing the response obtained by a circular movement of the background while the monkeys fixated a stationary target. The distribution of the preferred directions was isotropic and showed no ipsiversive bias. MT neurons were excited in a directionally selective manner during the execution of optokinetic nystagmus, in a similar way to that produced by visual stimulation during fixation. The majority of neurons showed a sensitivity to the velocity of retinal image slip. Activity during the execution of optokinetic nystagmus could be traced back to residual retinal image slip in the direction of optokinetic stimulation. No dynamic effects of the neuronal activity during the build-up of eye velocity in early optokinetic nystagmus were observed. Obviously, the activity in area MT did not reflect the charging of the velocity storage mechanism. Accordingly, following the cessation of stimulation, the activity dropped to the level of spontaneous activity and did not parallel the execution of optokinetic afternystagmus. These results suggest that area MT is not part of the velocity storage mechanism and, furthermore, that the storage mechanism must be downstream of area MT in the processing of visual motion for the generation of the optokinetic nystagmus and afternystagmus.
在两只猕猴三个脑半球的MT区的148个神经元中测定了视觉反应特性的方向选择性。通过分析当猴子注视静止目标时背景做圆周运动所获得的反应，得到了每个神经元的偏好方向。偏好方向的分布是各向同性的，没有同侧性偏向。在视动性眼震执行期间，MT神经元以方向选择性的方式被兴奋，类似于注视期间视觉刺激所产生的方式。大多数神经元对视网膜图像滑动速度敏感。视动性眼震执行期间的活动可追溯到视动性刺激方向上的残余视网膜图像滑动。在早期视动性眼震眼速度增加过程中，未观察到神经元活动的动态效应。显然，MT区的活动并未反映速度存储机制的充电情况。因此，在刺激停止后，活动降至自发活动水平，且与视动性眼震后眼震的执行情况不一致。这些结果表明，MT区不是速度存储机制的一部分，此外，在视觉运动处理中，为了产生视动性眼震和眼震后眼震，速度存储机制必定位于MT区的下游。
