演題番号 : P1-m13
本多 祥子 / Yoshiko Honda:1 古田 貴寛 / Takahiro Furuta:2 金子 武嗣 / Takeshi Kaneko:2 柴田 秀史 / Hideshi Shibata:3 佐々木 宏 / Hiroshi Sasaki:1
1:東京女子医科大学・医・解剖学 / Dept. Anatomy, School of Medicine, Tokyo Women's Medical Univ., Tokyo 2:京都大学大学院・医学研究科・高次脳形態学 / Dept. Morphological Brain Science, Graduate School of Medicine, Kyoto Univ., Kyoto 3:東京農工大学大学院・農学研究院・獣医解剖学 / Lab. Veterinary Anatomy, Inst. Agricultural Science, Tokyo Univ. Agriculture and Technology., Tokyo
Layer V of the presubiculum is considered to be a major output layer, which sends many efferent fibers to several parahippocampal and subcortical areas, such as the medial entorhinal area (MEA), retrosplenial cortex (RS), subiculum (Sub), anterior and laterodorsal thalamic nuclei and lateral mammillary nucleus. However, there is no information about the axonal branching patterns of each projection neuron in layer V. We studied the axonal morphology of single layer V neurons of the presubiculum, which were visualized in the rat with a viral vector expressing membrane-targeted green fluorescent protein. Patterns of axonal collateralization of single layer V pyramidal neurons were different in each septotemporal part of the presubiculum. In the septal half of the presubiculum, a single layer V pyramidal neuron provides its axon only to RS with short recurrent collaterals reaching layers V or VI of the presubiculum. In the mid-septotemporal part of the presubiculum, a single layer V pyramidal neuron sends its axon to both RS and Sub. During the courses to these areas, each of the axonal branches gives off some recurrent collaterals mainly to layers V and VI of the presubiculum. In the temporal part, there was a layer V pyramidal neuron, which sends its axonal branches to Sub, deep layers of MEA and subcortical areas, but not to RS. During the courses to these areas, each of the axonal branches provides many recurrent collaterals not only to layers V and VI, but also layers I-III of the presubiculum. Our data demonstrate for the first time that the patterns of axonal collateralization of single layer V pyramidal neurons are different depending on the location of the cell bodies along the septotemporal axis of the presubiculum.