Pheromone discrimination ability of olfactory bulb mitral and ruffed cellsin the goldfish (Carassius auratus)

Significant anatomical differences characterizing mitral cells and ruffed c ells were published by Kosaka and Hama in three teleost species. Physiologi cal responses from both types of relay neurons have now been recorded extra cellularly and simultaneously in the plexiform layer using a single tungste n microelectrode. During interstimulus intervals mitral cells responded wit h higher, frequently burst-like impulse rates triggered by the activity of epithelial receptor neurons. Ruffed cell impulse rates were low, and each a ction potential triggered a long-lasting, continuously variable, integrated granule cell potential. During olfactory stimulation with important biolog ical stimuli such as preovulatory and ovulatory pheromones, a probable alar m pheromone and amino acids contrasting interactions between mitral cells a nd ruffed cells resulting in a drastic intensification of centrally transmi tted information were frequently recorded. Individual neurons excellently d iscriminated stimuli. Irrespective of the physiological relevance of stimul i, however, similarities were recorded in the distribution of excitatory, i nhibitory and indifferent responses.