Properties of the olfactory efferent system.

Abstract

SUMMARYAppropriately timed afferent stimulation of one olfactory bulb can depress afferent induced activity in the opposite bulb, the depression being mediated by the true commissural component of the anterior commissure which is part of the olfactory efferent system. Bulbar retrograde responses evoked by lateral olfactory tract stimulation are depressed by continuous high frequency stimulation of the anterior commissure, and this is considered to be further evidence for a depressive action of the efferent system in the olfactory bulb. Stimulation of the efferent system evokes monophasic negative waves in the bulb which, on continuous stimulation, summate to give a sustained negativity. The appearance of this negative shift is correlated with the onset of the depressive influence. Lateral olfactory tract stimulation evokes polyphasic, dominantly positive, waves in the bulb which do not summate but rapidly fatigue on repetitive stimulation at high frequencies.