Influence of some biologically meaningful odorants on the vigilance states of the rat.

In freely moving rats, mitral cells multiunit activity and vigilance states (EEG and neck muscles EMG) were recorded during stimulations by some odorous stimuli known from previous experiments to elicit distinct emotional behaviors. An awaking influence may be pointed out; the greatest awaking influence is noted for the opposite most biologically meaningful stimuli: odor of fox (predator of the rat) and odor of grouped rats. Mitral cells responsiveness is not only modulated by the biological meaning of the olfactory stimulus but is also under the control of the arousal level of the animal; it decreases from wakefulness (W) to slow wave sleep (SWS).