Hamam Bassam N, Amaral David G, Alonso Angel A
Department of Neurology and Neurosurgery, Montreal Neurological Institute and McGill University, Montreal, Quebec H3A-2B4, Canada.
J Comp Neurol. 2002 Sep 9;451(1):45-61. doi: 10.1002/cne.10335.
The intrinsic electrophysiological and morphological properties of lateral entorhinal area (LEA) layer V neurons were investigated by sharp electrode intracellular recording and biocytin labeling in vitro. The morphological analysis revealed that layer V of the LEA contains three distinct subtypes of principal neurons, which were classified as pyramidal, horizontal, and polymorphic neurons. Pyramidal cells were the most abundant subtype (57%) and could be further subdivided into neurons with large, small, and star-like somas. Similarly to pyramidal cells, horizontal neurons (11%) had a prominent apical dendrite. However, their distinctive basal dendritic plexus extended primarily in the horizontal plane. Polymorphic neurons (32%) were characterized by a multipolar dendritic organization. Electrophysiological analysis of neurons in the three categories demonstrated a diversity of electrophysiological profiles within each category and no significant differences between groups. Neurons in the three subgroups could display instantaneous and/or time-dependent inward rectification and different degrees of spike frequency adaptation. None of the recorded cells displayed an intrinsic oscillatory bursting discharge. Many neurons in the three subgroups, however, displayed slow (3.5-14 Hz), sustained, subthreshold membrane potential oscillations. The morphological and electrophysiological diversity of principal neurons in the LEA parallels that previously reported for the medial entorhinal area and suggests that, with respect to the deep layers, similar information processing is performed across the mediolateral extent of the entorhinal cortex. Layer V of the entorhinal cortex may undertake very complex operations beyond acting as a relay station of hippocampal processed information to the neocortex.
通过体外尖锐电极细胞内记录和生物素标记，研究了外侧内嗅区（LEA）第V层神经元的内在电生理和形态学特性。形态学分析显示，LEA的第V层包含三种不同亚型的主要神经元，分别被归类为锥体细胞、水平细胞和多形细胞。锥体细胞是最丰富的亚型（57%），可进一步细分为具有大、小和星形胞体的神经元。与锥体细胞类似，水平细胞（11%）有一个突出的顶树突。然而，它们独特的基底树突丛主要在水平平面延伸。多形细胞（32%）的特征是多极树突组织。对这三类神经元的电生理分析表明，每一类中电生理特征存在多样性，而各组之间无显著差异。这三个亚组中的神经元可表现出瞬时和/或时间依赖性内向整流以及不同程度的放电频率适应。所记录的细胞均未表现出内在振荡爆发性放电。然而，这三个亚组中的许多神经元表现出缓慢（3.5 - 14 Hz）、持续的阈下膜电位振荡。LEA中主要神经元的形态和电生理多样性与先前报道的内侧内嗅区相似，这表明就深层而言，在内嗅皮质的内外侧范围内进行着类似的信息处理。内嗅皮质的第V层可能承担着非常复杂的操作，而不仅仅是作为海马处理信息到新皮质的中继站。
