Cd. Balaban et G. Beryozkin, ORGANIZATION OF VESTIBULAR NUCLEUS PROJECTIONS TO THE CAUDAL DORSAL CAP OF KOOY IN RABBITS, Neuroscience, 62(4), 1994, pp. 1217-1236
This study used retrograde and anterograde tracing methods to characte
rize the origin and terminal distribution of vestibular nuclear projec
tions to the caudal dorsal cap of the inferior olive in albino rabbits
. Comparisons of the retrograde labeling patterns from Cholera toxin B
fragment-horseradish peroxidase and Fluoro-Gold injection sites centr
ed in either the caudal dorsal cap or the rostral dorsal cap plus vent
rolateral outgrowth revealed that they receive projections from differ
ent vestibular nuclear regions. Tracer injections in the rostral dorsa
l cap and ventrolateral outgrowth produced a sparse bilateral distribu
tion of labeled neurons in the superior vestibular nucleus and an almo
st exclusively ipsilateral pattern of labeled neurons in caudal pars a
lpha of the lateral vestibular nucleus. Injections in the caudal dorsa
l cap, though, labeled neurons bilaterally in the rostral medial vesti
bular nucleus, predominantly ipsilaterally in pars beta of the lateral
vestibular nucleus and almost exclusively ipsilaterally in caudal par
s alpha of the lateral vestibular nucleus and the rostral aspect of th
e inferior vestibular nucleus. Vestibular nucleus injections of the an
terograde tracer Phaseolus vulgaris leucoagglutinin indicated (1) that
a predominantly ipsilateral projection to the caudal dorsal cap origi
nates bilaterally from the pars beta of the lateral vestibular nucleus
and the rostroventral aspect of the rostral medial vestibular nucleus
, (2) that the medial half of the caudal medial vestibular nucleus is
the source of a predominantly contralateral projection to dorsal cap,
(3) that the caudal aspect of nucleus prepositus hypoglossi contribute
s a predominantly ipsilateral projection to the medial accessory olive
and (4) that the rostral aspect of inferior vestibular nucleus and th
e dorsal and lateral aspects of the caudal medial vestibular nucleus p
roject to nucleus beta of the medial accessory olive. In addition, axo
ns containing anterogradely transported PHA-L were observed bilaterall
y in the oculomotor and abducens nuclei from injection sites involving
pars beta of the lateral vestibular nucleus. It is hypothesized that
bilateral vestibulo-caudal dorsal cap pathways coordinate activity in
the left and right flocculus and nodulus during horizontal head moveme
nts to facilitate the performance of conjugate vestibule-ocular and op
tokinetic reflexes.