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Topographical organization of projections from the subiculum to the hypothalamus in the rat
Author(s) -
Kishi Toshiro,
Tsumori Toshiko,
Ono Katsuhiko,
Yokota Shigefumi,
Ishino Hiroshi,
Yasui Yukihiko
Publication year - 2000
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(20000403)419:2<205::aid-cne5>3.0.co;2-0
Subject(s) - subiculum , mammillary body , hypothalamus , anatomy , neuroscience , anterograde tracing , retrograde tracing , biology , suprachiasmatic nucleus , thalamus , dorsum , hippocampus , dentate gyrus
The projections from the subiculum to the hypothalamus were comprehensively examined in the rat by using the anterograde Phaseolus vulgaris leucoagglutinin (PHA‐L) and retrograde cholera toxin B subunit (CTb) methods. Tracing of efferents with PHA‐L indicated that the medial preoptic region received projection fibers from the temporal two‐thirds of the subiculum, whereas the anterior, tuberal, and mammillary regions received those from the full longitudinal extent of the subiculum. The subicular projections to the anterior and tuberal hypothalamic regions were also found to be organized in a topographical manner such that the temporal‐to‐septal axis of origin in the subiculum determined a ventromedial‐to‐dorsolateral axis of termination in the medial zone of the hypothalamus: Massive labeled fibers from the temporalmost part of the subiculum terminated in the subparaventricular zone and its caudal continuum around the dorsal and medial aspects of the ventromedial nucleus, and those from progressively more septal parts terminated in progressively more dorsolateral parts of the medial zone. In addition, the temporal‐to‐septal axis of origin in the subiculum tended to determine a medial‐to‐lateral axis of termination in the preoptic region as well as a ventral‐to‐dorsal axis of termination in the mammillary region. Furthermore, the temporal‐to‐septal axis of origin in the septal two‐thirds of the subiculum corresponded to a ventrolateral‐to‐dorsomedial axis of termination in the medial mammillary nucleus. The topographical projections from the subiculum to the medial zone of the hypothalamus were confirmed by CTb experiments, representatively in the subicular projections to the anterior hypothalamic region. These results suggest that different populations of neurons existing along the longitudinal axis of the subiculum may exert their influences on the execution of different hypothalamic functions. J. Comp. Neurol. 419:205–222, 2000. © 2000 Wiley‐Liss, Inc.