Filion M, Tremblay L, Matsumura M, Richard H
Centre de recherche en neurobiologie, Université Laval et Hôpital de l'Enfant-Jésus, Québec, Canada.
Rev Neurol (Paris). 1994 Aug-Sep;150(8-9):627-33.
Data in the literature support two apparently contradictory hypotheses: that of parallel processing and that of informational convergence in the basal ganglia. We present electrophysiological data supporting one and the other. Thus, at the output of the basal ganglia, in the intact monkey, neurons of the pallidum respond almost exclusively and in small number to passive limb movement. The specificity of the responses supports the parallel processing hypothesis. However, when the monkey is rendered parkinsonian by the neurotoxin MPTP, the dopaminergic deficit discloses a strong convergence upon pallidal neurons of information originating from different body parts. Such a convergence is also observed in the case of pallidal responses to electrical stimulation of the striatum. According to data in the recent literature, it is more likely that this information converges into the pallidum through the subthalamo-pallidal rather than the striato-pallidal pathway. On the other hand, pallidal responses to electrical stimulation of the striatum display a topological antagonistic center-surround organization, probably resulting from lateral inhibition. Moreover, changes in neuronal activities induced in the external pallidal segment by local injection of bicuculline display a similar organization and suggest the occurrence of a wide and powerful lateral inhibition in this pallidal segment. Such focusing mechanisms would be useless in an exclusively parallel system. One may therefore think that, in the normal individual, the level of dopamine dynamically focuses the system on the appropriate information. This would allow parallel processing in neuronal channels that are only relatively independent, since they can also demonstrate informational convergence.
基底神经节中的并行处理假说和信息汇聚假说。我们展示了支持这两种假说的电生理数据。因此，在基底神经节的输出端，在正常猴子中，苍白球神经元几乎仅对被动肢体运动做出少量反应。这些反应的特异性支持并行处理假说。然而，当猴子因神经毒素MPTP而患帕金森病时，多巴胺能缺陷揭示了源自不同身体部位的信息强烈汇聚于苍白球神经元。在苍白球对纹状体电刺激的反应中也观察到这种汇聚。根据近期文献中的数据，这种信息更有可能通过丘脑底核 - 苍白球通路而非纹状体 - 苍白球通路汇聚到苍白球。另一方面，苍白球对纹状体电刺激的反应呈现出拓扑拮抗的中心 - 外周组织，这可能是由侧向抑制导致的。此外，通过局部注射荷包牡丹碱在苍白球外侧段诱导的神经元活动变化呈现出类似的组织形式，并表明在该苍白球段存在广泛而强大的侧向抑制。这种聚焦机制在一个完全并行的系统中是无用的。因此可以认为，在正常个体中，多巴胺水平动态地将系统聚焦于适当的信息。这将允许在仅相对独立的神经元通道中进行并行处理，因为它们也能表现出信息汇聚。
