M. Serafin et al., ELECTROPHYSIOLOGICAL STUDY OF NUCLEUS GIGANTOCELLULARIS NEURONS IN GUINEA-PIG BRAIN-STEM SLICES, Neuroscience, 73(3), 1996, pp. 797-805
Gigantocellular neurons of the medullary nucleus gigantocellularis rep
resent a major source of reticulospinal pathways. Among other roles, t
hey have been involved in the processing of vestibular information. Th
e aim of the present study was to describe the major intrinsic membran
e properties of these cells in guinea-pig brainstem slices. We found n
ucleus gigantocellularis neurons to be segregated in two cell types. T
ype A nucleus gigantocellularis neurons were characterized by the pres
ence of a single large afterhyperpolarization and a potent transient 4
-aminopyridine-sensitive rectification likely due to the presence of a
transient outward potassium current. In contrast, type B nucleus giga
ntocellularis neurons had a narrower and faster rising action potentia
l followed by an early fast and a delayed slower afterhyperpolarizatio
n. In contrast to type A neurons, type B neurons were, in addition, en
dowed with subthreshold tetrodotoxin-sensitive sodium-dependent platea
u potentials. Whereas both cell types were endowed with high-threshold
calcium-dependent action potentials, only type B nucleus gigantocellu
laris neurons also displayed long-lasting calcium-dependent plateau po
tentials. These results show that nucleus gigantocellularis neurons ca
n be segregated by their intrinsic membrane properties in two cell typ
es which are very similar to those that we have previously described i
n the medial vestibular nucleus. The possibility that these difference
s between type A and B neurons might play a role in the segregation be
tween tonic and kinetic cells is discussed. Copyright (C) 1996 IBRO. P
ublished by Elsevier Science Ltd.