Control of the rat olfactory bulb activity induced by biologically significant odors (author's transl)

In acute experiments, unitary activity was recorded from mitral cells of the rat olfactory bulb. The animals were stimulated with odors that have been shown in previous experiments to give a distinct emotional behavior. In curarized rats an odor giving alarm behavior evoked a greater number of inhibitory than excitatory responses was elicited by a neutral odor. In rats under Nembutal anesthesia an alarming odor evoked a greater number of inhibitory than excitatory responses; a reassuring odor evoked a greater number of excitatory than inhibititory responses; and equal number of inhibitory and excitatory responses; a reassuring or a neutral odor evoked an equal number of inhibitory and excitatory responses. After sectioning the olfactory peduncles, the difference in ratio between excitatory and inhibitory responses for alarming or reassuring odors was no longer present. The results are discussed in terms of a modulation of mitral cell activity by higher nervous centers in relation to the biological significance of the stimulating odors.