The nervus terminalis of the shark: the effect of efferent impulses on ganglion cell activity.

Tonic activity was recorded extracellularly in the nervus terminalis of the bonnethead shark. Cutting or cooling the nerve central to its ganglion eliminated these spikes, and was followed by an increase in multi-unit activity which appeared to arise from the ganglion. After cutting centrally, electrical stimulation of the distal stump of the nerve suppressed this multi-unit activity. The data suggest that efferent impulses may normally suppress ganglion cell activity.