Large mechanical changes in the bullfrog olfactory bulb evoked by afferent fiber stimulation.

The isolated olfactory bulb of the bullfrog responds to olfactory nerve stimulation with large mechanical changes in the bulb. The sequence of these changes represents: (1) swelling of the bulb associated with action potential production in the secondary neurons; (2) shrinkage during powerful inhibition of the secondary neurons; and (3) swelling accompanied by repetitive firing of action potentials in the bulb. The effects of bicuculline and Cl-free Ringer on these mechanical changes were examined. The shrinkage of the bulb is closely related with the inhibitory postsynaptic potentials (IPSPs) in the mitral cells.