Bevan M D, Booth P A, Eaton S A, Bolam J P
Medical Research Council Anatomical Neuropharmacology Unit, Oxford, OX1 3TH, United Kingdom.
J Neurosci. 1998 Nov 15;18(22):9438-52. doi: 10.1523/JNEUROSCI.18-22-09438.1998.
A subpopulation of neurons in the globus pallidus projects to the neostriatum, which is the major recipient of afferent information to the basal ganglia. Given the moderate nature of this projection, we hypothesized that the pallidostriatal projection might exert indirect but powerful control over principal neuron activity by targeting interneurons, which comprise only a small percentage of neostriatal neurons. This was tested by the juxtacellular labeling and recording of pallidal neurons in combination with immunolabeling of postsynaptic neurons. In addition to innervating the subthalamic nucleus and output nuclei, 6 of 23 labeled pallidal neurons projected to the neostriatum. Both the firing characteristics and the extent of the axonal arborization in the neostriatum were variable. However, light and electron microscopic analysis of five pallidostriatal neurons revealed that each neuron selectively innervated neostriatal interneurons. A large proportion of the boutons of an individual axon (19-66%) made contact with parvalbumin-immunoreactive interneurons. An individual parvalbumin-immunoreactive neuron (n = 27) was apposed on average by 6.7 boutons (SD = 6.1) from a single pallidal axon (n = 2). Individual pallidostriatal boutons typically possessed more than one symmetrical synaptic specialization. In addition, 3-32% of boutons of axons from four of five pallidal neurons contacted nitric oxide synthase-immunoreactive neurons. Descending collaterals of pallidostriatal neurons were also found to make synaptic contact with dopaminergic and GABAergic neurons of the substantia nigra. These data imply that during periods of cortical activation, individual pallidal neurons may influence the activity of GABAergic interneurons of the neostriatum (which are involved in feed-forward inhibition and synchronization of principle neuron activity) while simultaneously patterning neuronal activity in basal ganglia downstream of the neostriatum.
苍白球中的一个神经元亚群投射到新纹状体，新纹状体是基底神经节传入信息的主要接收者。鉴于该投射的适度性质，我们推测苍白球-纹状体投射可能通过靶向中间神经元对主要神经元活动施加间接但强大的控制，中间神经元仅占新纹状体神经元的一小部分。通过对苍白球神经元进行近胞体标记和记录，并结合对突触后神经元的免疫标记来对此进行测试。除了支配丘脑底核和输出核外，23个标记的苍白球神经元中有6个投射到新纹状体。新纹状体中轴突分支的放电特征和范围都是可变的。然而，对五个苍白球-纹状体神经元的光镜和电镜分析表明，每个神经元都选择性地支配新纹状体中间神经元。单个轴突的大部分终扣（19%-66%）与小白蛋白免疫反应性中间神经元接触。平均而言，单个小白蛋白免疫反应性神经元（n = 27）被来自单个苍白球轴突（n = 2）的6.7个终扣（标准差 = 6.1）所毗邻。单个苍白球-纹状体终扣通常具有不止一个对称的突触特化结构。此外，五个苍白球神经元中有四个的轴突终扣的3%-32%与一氧化氮合酶免疫反应性神经元接触。还发现苍白球-纹状体神经元的下行侧支与黑质的多巴胺能和GABA能神经元形成突触联系。这些数据表明，在皮质激活期间，单个苍白球神经元可能会影响新纹状体中GABA能中间神经元的活动（这些中间神经元参与前馈抑制和主要神经元活动的同步），同时对新纹状体下游基底神经节中的神经元活动进行模式化。
