Failure of the Bulbar Inhibitory Reticular Formation to Affect Somatic Reflex Activity in the Unanesthetized Cat

¹ From the Department of Physiology, Tulane University School of Medicine, New Orleans, Louisiana

Bulbar inhibition of the patellar reflex was obtained under Nembutal anesthesia in cats at surgery when stimulating electrodes were implanted aseptically in the medullary reticular formation. After periods of 72–322 hours of postoperative recovery it was impossible to obtain inhibition of the patellar reflex even at stimulus voltages which produced convulsive activity. Reinduction of Nembutal anesthesia prior to killing always resulted in the reappearance of bulbar inhibition. Autonomic, respiratory and EEG desynchronization effects were always obtainable whether or not the animal was anesthetized. Etherized animals exhibited the usual bulbar inhibition of the patellar reflex, lost the inhibition when when removed from ether and regained the inhibition when re-anesthetized with ether. The authors conclude that either chemical (anesthetic) or surgical (decerebrate) removal of suprabulbar structures is required for the demonstration of bulbar reticular inhibition of the patellar reflex by direct stimulation of the reticular formation.