Mednikova Y S, Karnup S V
Institute of Higher Nervous Activity and Neurophysiology, Moscow, Russia.
Neuroscience. 1995 Nov;69(1):115-23. doi: 10.1016/0306-4522(95)00189-p.
On guinea-pig neocortical slices the spatial organization of dendrites sensitive to excitatory amino acids was studied. Extracellular recording were obtained from the the soma of layer V neurons. Responses of 135 neurons to iontophoretically applied glutamate or aspartate have been analysed. An increased firing rate to somatic and most of dendritic applications were of short latency not exceeding 500 ms. Dendritic applications caused somatic responses with far longer latencies (up to 2-3 s) in 18% of cases. Latencies of responses to excitatory amino acids applied to several dendritic sites of the same neuron had similar values. The greatest reactions were obtained in response to excitatory amino acids imposed to the soma and proximal dendrites. At a distance of 100 microm beyond the soma in the basal region and region and further than 300 microm in the apical region excitatory amino acid applications produced two to three times less intensive somatic response. The area where dendritic activation gave rise to change in neuronal firing was confined to 350 and 800 microm for basal and apical dendrites, respectively. Topography of effective dendritic sites fell into the area corresponding to anatomically known outline of dendritic tree of pyramidal neurons. This fact implies that in our experiments we basically dealt with layer V pyramids. The results obtained suggest that local activation of distal dendrites may elicit spike generation in the soma. Different electrical properties of somatic and dendritic membranes are discussed.
在豚鼠新皮质切片上，研究了对兴奋性氨基酸敏感的树突的空间组织。从第V层神经元的胞体进行细胞外记录。分析了135个神经元对离子电泳施加的谷氨酸或天冬氨酸的反应。对胞体和大多数树突施加刺激时，放电频率增加，潜伏期短，不超过500毫秒。在18%的情况下，对树突施加刺激会引起潜伏期长得多（长达2 - 3秒）的胞体反应。对同一神经元的几个树突部位施加兴奋性氨基酸时，反应潜伏期的值相似。对胞体和近端树突施加兴奋性氨基酸时获得的反应最大。在基部区域距胞体100微米以外以及顶端区域超过300微米处，施加兴奋性氨基酸产生的胞体反应强度要低两到三倍。树突激活引起神经元放电变化的区域，基部树突和顶端树突分别局限于350微米和800微米。有效树突部位的拓扑结构位于与锥体神经元树突的解剖学已知轮廓相对应的区域。这一事实表明，在我们的实验中，我们主要处理的是第V层锥体神经元。获得的结果表明，远端树突的局部激活可能会在胞体中引发动作电位发放。文中还讨论了胞体膜和树突膜不同的电特性。
