Baizer J S, Kralj-Hans I, Glickstein M
Department of Physiology, SUNY, Buffalo, New York 14214, USA.
J Neurophysiol. 1999 Apr;81(4):1960-5. doi: 10.1152/jn.1999.81.4.1960.
If a laterally displacing prism is placed in front of one eye of a person or monkey with the other eye occluded, they initially will point to one side of a target that is located directly in front of them. Normally, people and monkeys adapt easily to the displaced vision and correct their aim after a few trials. If the prism then is removed, there is a postadaptation shift in which the subject misses the target and points in the opposite direction for a few trials. We tested five Macaque monkeys for their ability to adapt to a laterally displacing prism and to show the expected postadaptation shift. When tested as normals, all five animals showed the typical pattern of adaptation and postadaptation shift. Like human subjects, the monkeys also showed complete interocular transfer of the adaptation but no transfer of the adaptation between the two arms. When preoperative training and testing was complete, we made lesions of various target areas on the cerebellar cortex. A cerebellar lesion that included the dorsal paraflocculus and uvula abolished completely the normal prism adaptation for the arm ipsilateral to the lesion in one of the five monkeys. The other four animals retained the ability to prism-adapt normally and showed the expected postadaptation shift. In the one case in which the lesion abolished prism adaptation, the damage included Crus I and II, paramedian lobule and the dorsal paraflocculus of the cerebellar hemispheres as well as lobule IX, of the vermis. Thus in this case, the lesion included virtually all the cerebellar cortex that receives mossy-fiber visual information relayed via the pontine nuclei from the cerebral cortex. The other four animals had damage to lobule V, the classical anterior lobe arm area and/or vermian lobules VI/VII, the oculomotor region. When tested postoperatively, some of these animals showed a degree of ataxia equivalent to that of the case in which prism adaptation was affected, but prism adaptation and the postadaptation shift remained normal. We conclude that in addition to its role in long-term motor learning and reflex adaptation, the region of the cerebellum that was ablated also may be a critical site for a short-term motor memory. Prism adaptation seems to involve a region of the cerebellum that receives a mossy-fiber visual error signal and probably a corollary discharge of the movement.
如果将一个使影像向外侧移位的棱镜置于人的一只眼前，同时遮挡另一只眼，人和猴子最初会指向位于他们正前方目标的一侧。正常情况下，人和猴子很容易适应这种移位的视觉，并在几次尝试后校正他们的瞄准。如果随后移除棱镜，会出现适应后偏移，即受试者会错过目标并在相反方向指向几次。我们测试了五只猕猴适应使影像向外侧移位的棱镜并表现出预期的适应后偏移的能力。当作为正常情况进行测试时，所有五只动物都表现出典型的适应和适应后偏移模式。与人类受试者一样，猴子也表现出适应的完全眼间转移，但两臂之间没有适应转移。术前训练和测试完成后，我们在小脑皮质的各个目标区域制造损伤。包括背侧副绒球和蚓垂的小脑损伤完全消除了五只猴子中一只猴子患侧手臂的正常棱镜适应。其他四只动物保留了正常棱镜适应的能力，并表现出预期的适应后偏移。在损伤消除棱镜适应的那个案例中，损伤包括小脑半球的I和II脚、旁正中小叶和背侧副绒球以及蚓部的IX小叶。因此，在这种情况下，损伤几乎包括了所有从小脑皮质接收经由脑桥核从大脑皮质中继而来的苔藓纤维视觉信息的区域。其他四只动物的V小叶、经典的前叶手臂区域和/或蚓部小叶VI/VII（动眼神经区域）受到损伤。术后测试时，其中一些动物表现出与棱镜适应受影响的案例相当程度的共济失调，但棱镜适应和适应后偏移仍然正常。我们得出结论，除了其在长期运动学习和反射适应中的作用外，被切除的小脑区域也可能是短期运动记忆的关键部位。棱镜适应似乎涉及小脑的一个区域，该区域接收苔藓纤维视觉误差信号，并且可能接收运动的伴随放电。
