Westby G W, Collinson C, Redgrave P, Dean P
Department of Psychology, Sheffield University, UK.
Eur J Neurosci. 1994 Aug 1;6(8):1335-42. doi: 10.1111/j.1460-9568.1994.tb00324.x.
We recently showed (Westby et al., Eur. J. Neurosci., 5, 1378-1388, 1993) that the cerebellar interpositus nucleus is a source of excitatory drive for a population of spontaneously active neurons in the lateral intermediate layers of the contralateral superior colliculus. Anatomical and physiological studies have shown that this region of the colliculus contains cells of origin of the crossed descending tectoreticulospinal tract and receives GABAergic input from the ipsilateral basal ganglia. In the present study we tested the hypothesis that the same neurons receiving excitatory drive from the cerebellum also receive tonic inhibitory input from the substantia nigra pars reticulata. From a sample of 73 spontaneously active collicular cells we found that in 53% the firing rate was suppressed by GABA microinjection into the contralateral deep cerebellar nuclei; a further 15% showed a frequency increase. Of the collicular cells identified as receiving excitatory cerebellar input, 85% were found to be disinhibited by nigral GABA microinjection. The remainder were all inhibited by nigral GABA. These data show that the main excitatory influence from the cerebellum and the main inhibitory influence from the substantia nigra converge on at least one population of spontaneously active cells in the lateral intermediate layers of the superior colliculus. This finding is discussed in relation to the possible function of these spontaneous cells in movement control and nociception.
我们最近的研究表明（韦斯特比等人，《欧洲神经科学杂志》，第5卷，第1378 - 1388页，1993年），小脑间位核是对侧上丘外侧中间层一群自发活动神经元兴奋性驱动的来源。解剖学和生理学研究表明，上丘的这个区域包含交叉的下行顶盖网状脊髓束的起源细胞，并接受来自同侧基底神经节的GABA能输入。在本研究中，我们检验了这样一个假设：那些从小脑接受兴奋性驱动的相同神经元，也接受来自黑质网状部的紧张性抑制性输入。从73个自发活动的上丘细胞样本中，我们发现，向对侧小脑深部核团微量注射GABA后，53%的细胞放电率受到抑制；另有15%的细胞放电频率增加。在被确定为接受小脑兴奋性输入的上丘细胞中，发现85%的细胞在向黑质微量注射GABA后解除了抑制。其余细胞均被黑质GABA抑制。这些数据表明，来自小脑的主要兴奋性影响和来自黑质的主要抑制性影响汇聚于上丘外侧中间层至少一群自发活动的细胞。结合这些自发细胞在运动控制和痛觉感受中的可能功能对这一发现进行了讨论。
