AJP - Regulatory, Integrative and Comparative Physiology, Vol 246, Issue 3 389-R395, Copyright © 1984 by American Physiological Society
Brain stem reticular influences on lumbar axial muscle activity. I. Effective sites
P. A. Femano, S. Schwartz-Giblin and D. W. Pfaff
Lumbar axial muscle responses to electrical stimulation of the brain stem
reticular formation were used to characterize reticular influences on these
muscles. Electromyographic recordings were obtained from the
transversospinalis, medial longissimus, and lateral longissimus systems in
the urethan-anesthetized rat. Ipsilateral stimulation of the pontomedullary
reticular formation evoked excitatory responses in these muscles. Trains of
pulses were required, but currents as low as 15 microA were effective.
Contralateral reticular stimulation with currents similar to those that
elicited activation during ipsilateral stimulation at the same brain stem
levels could inhibit lumbar electromyographic activity. The results suggest
that the motoneurons innervating the lumbar axial musculature in the rat
receive strong reticulospinal influences that could be important for
postural maintenance and the expression of certain behaviors.
