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Morphological correlations between spontaneously discharging primary vestibular afferents and vestibular nucleus neurons in the cat
Author(s) -
Sato Fumi,
Sasaki Hiroshi
Publication year - 1993
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/cne.903330408
Subject(s) - vestibular nuclei , biology , vestibular system , horseradish peroxidase , soma , postsynaptic potential , nucleus , neuron , anatomy , vestibular nerve , medial vestibular nucleus , semicircular canal , neuroscience , biochemistry , receptor , enzyme
Synaptic connections between physiologically classified primary vestibular afferents (PVAs) and their target vestibular nucleus (VN) neurons were examined by a combination of intra‐axonal staining and electron microscopic techniques. PVAs originating from the horizontal semicircular canal were electrophysiologically classified as either regular‐ or irregular‐type based on the regularity of their spontaneous discharge patterns, and were intra‐axonally labeled with horseradish peroxidase (HRP). HRP‐labeled PVAs of both types had many swellings along their course that contacted VN neurons. These swellings contained spherical synaptic vesicles and showed asymmetric postsynaptic specialization. Target VN neurons of both types of PVAs were distributed primarily in the superior, medial, and inferior VN. Irregular‐type PVAs made more axosomatic contacts than did regular‐type PVAs. The soma size of target VN neurons and the number of terminal boutons per target VN neuron were larger for irregular‐type PVAs than for regular‐type PVAs. Large VN neurons (presumably kinetic neurons) were innervated exclusively by irregular‐type PVAs. Small VN neurons were innervated by PVAs of the regular‐type and the irregular‐type. These results demonstrate that there is a correlation between the physiological properties and morphological characteristics of PVAs and their target VN neurons. © 1993 Wiley‐Liss, Inc.