Tahvildari Babak, Alonso Angel
Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada.
J Comp Neurol. 2005 Oct 17;491(2):123-40. doi: 10.1002/cne.20706.
The intrinsic electrophysiology and morphology of neurons from layers II and III of the lateral entorhinal cortex (EC) was investigated in a rat brain slice preparation by intracellular recording and biocytin labeling. Morphologically, we distinguished three groups of layer II principal neurons. The most numerous group included cells with multiple radiating dendrites that spread over layers II and I in a fan-like fashion. While morphologically "fan" neurons were similar to the "stellate" cells of the medial EC, electrophysiologically the fan cells lacked the persistent rhythmic subthreshold oscillations and the very pronounced time-dependent inward rectification typical of the stellate cells. The second group consisted of pyramidal cells that manifested regular spike firing and had a more negative resting potential and a longer spike duration than the fan cells. In the third group we included all those neurons that had diverse multipolar appearances distinct from the fan cells. Neurons in this group had electrophysiological profiles intermediate between those of the fan and pyramidal cells. All neurons recorded in layer III were pyramidal in shape with a basal dendritic tree that could extend into layer V and an axon that could also give off collaterals into layer V. Electrophysiologically, layer III pyramidal cells were very similar to those of layer II. On the basis of these and other data we suggest that in different EC regions layer II neurons may be conducting more input-dependent specialized processing, while cells from layer III may perform a more global or generalized function.
通过细胞内记录和生物素标记，在大鼠脑片标本中研究了外侧内嗅皮层（EC）第II层和第III层神经元的内在电生理学和形态学。在形态学上，我们区分出三组第II层主要神经元。数量最多的一组包括具有多个放射状树突的细胞，这些树突以扇形方式分布在第II层和第I层。虽然形态学上的“扇形”神经元与内侧EC的“星状”细胞相似，但在电生理学上，扇形细胞缺乏星状细胞典型的持续性节律性阈下振荡和非常明显的时间依赖性内向整流。第二组由表现出规则锋电位发放的锥体细胞组成，其静息电位比扇形细胞更负，锋电位持续时间更长。在第三组中，我们纳入了所有那些具有不同于扇形细胞的多样多极外观的神经元。该组神经元的电生理特征介于扇形细胞和锥体细胞之间。在第III层记录的所有神经元均为锥体形，其基底树突可延伸至第V层，轴突也可向第V层发出侧支。在电生理学上，第III层锥体细胞与第II层锥体细胞非常相似。基于这些及其他数据，我们认为在不同的EC区域，第II层神经元可能进行更多依赖输入的专门处理，而第III层细胞可能执行更全局或普遍的功能。
