Bilkey D K, Schwartzkroin P A
Department of Neurological Surgery, University of Washington, Seattle 98195.
Brain Res. 1990 Apr 23;514(1):77-83. doi: 10.1016/0006-8993(90)90437-g.
A proportion of pyramidal cells in region CA3 of the mammalian hippocampus generate bursts of action potentials when stimulated with an intracellular injection of depolarizing current. Although a previous study has suggested that burst-type cells are more likely to be located in subregion CA3a than CA3b, it has been unclear if, or how, this burst-type firing was related to cell morphology. In the present study, a sample of pyramidal cells located in subregions CA3a, b and c were recorded intracellularly. Many of these cells were filled with Lucifer yellow, allowing correlation of gross morphology with electrophysiology. Contrary to previous results, it was determined that the proportion of cells which generated bursts did not differ significantly across CA3 subregions. It was found, however, that cells with somata located close to the stratum pyramidale (s.p.)/oriens border ('deep' cells) were more than twice as likely to generate burst-type responses than were cells located closer to stratum radiatum ('shallow' cells). One notable morphological feature of the deep cells was the greater length of the initial portion of their apical dendrite, as measured from soma to primary branching point. This observation is consistent with the hypothesis that burst-type responses are generated or modulated by ion channels on this section of the dendrite.
当用细胞内注入去极化电流刺激时，哺乳动物海马体CA3区的一部分锥体细胞会产生动作电位爆发。尽管先前的一项研究表明，爆发型细胞更有可能位于CA3a亚区而非CA3b亚区，但尚不清楚这种爆发型放电是否与细胞形态有关，以及如何相关。在本研究中，对位于CA3a、b和c亚区的锥体细胞样本进行了细胞内记录。这些细胞中的许多都用荧光黄填充，从而可以将大体形态与电生理学相关联。与先前的结果相反，研究确定在CA3亚区中产生爆发的细胞比例没有显著差异。然而，发现胞体位于靠近锥体层（s.p.）/原层边界的细胞（“深层”细胞）产生爆发型反应的可能性是位于靠近辐射层的细胞（“浅层”细胞）的两倍多。深层细胞的一个显著形态特征是其顶端树突起始部分从胞体到初级分支点的长度更长。这一观察结果与以下假设一致，即爆发型反应是由树突这一部分上的离子通道产生或调节的。
