Deniau J M, Chevalier G
Brain Res. 1985 May 20;334(2):227-33. doi: 10.1016/0006-8993(85)90214-8.
Besides the nigro-collicular pathway, the nigro-thalamic projection to the ventromedial thalamic nucleus represents another efferent system of the basal ganglia through which striatum can influence motor centers. Since the striato-nigrothalamic circuit is composed of two successive GABAergic inhibitory links and the SNR is tonically active, we tested that by inhibiting nigrothalamic cells, the striatum may exert a facilitatory influence on VM-thalamocortical cells. We show that a transitory block of SNR (substantia nigra pars reticulata) firing (induced by either intranigral application of GABA or by stimulating the inhibitory striato-nigral pathway), causes a perfectly time-locked increase of activity in a large number of VM cells projecting to motor cortex. Moreover, the striatally evoked excitation of VM-thalamocortical cells requires the functional integrity of the GABAergic striato-nigral link. We conclude that the double inhibitory striato-nigrothalamic pathway acts on VM-thalamocortical cells through a disinhibitory mechanism. The functional implication of such a mechanism is discussed.
除黑质-中脑顶盖通路外，黑质向丘脑腹内侧核的投射代表了基底神经节的另一个传出系统，纹状体可通过该系统影响运动中枢。由于纹状体-黑质-丘脑环路由两个连续的γ-氨基丁酸能抑制环节组成，且黑质网状部有紧张性活动，我们推测通过抑制黑质-丘脑细胞，纹状体可能对丘脑腹内侧-丘脑皮质细胞产生易化作用。我们发现，短暂阻断黑质网状部（SNR）的放电（通过向黑质内注射γ-氨基丁酸或刺激抑制性纹状体-黑质通路诱导），会导致大量投射至运动皮层的丘脑腹内侧细胞的活动出现完全同步的增加。此外，纹状体诱发的丘脑腹内侧-丘脑皮质细胞兴奋需要γ-氨基丁酸能纹状体-黑质环节的功能完整。我们得出结论，双重抑制性纹状体-黑质-丘脑通路通过去抑制机制作用于丘脑腹内侧-丘脑皮质细胞。本文讨论了这种机制的功能意义。
