Structure, Function and Evolution
Volume 519 pp.69-79

Electrophsiology of the Terminal Nerve in Cyprinids

National Institute for Physiological Sciences
Okazaki, Aichi 444, Japan

I studied the intracellular responses of the carp terminal nerve ganglion cells (TN cells) evoked by electrical stimulation of the olfactory nerve (ON), medial (MOT) or lateral (LOT) olfactory tracts. TN cells impaled were located in the medial part of the ON at the rostral level of the olfactory bulb. Intracellular staining showed that these cells were morphologically distinct from other neurons in the olfactory bulb. All TN cells showed long-lasting hyperpolarizing potentials in response to MOT stimulation, but showed no response to LOT stimulation. In about half of the TN cells, MOT stimulation also evoked an antidromic action potential. ON stimulation elicited no response in 24% of the TN cells (type I), while long-lasting hyperpolarizing potentials were evoked in the other 76% (type II). Responses to MOT, LOT and ON stimulation differed in several respects between the TN cells and mitral cells. The present results provide criteria for identifying the TN cells electrophysiologically.