Active and passive avoidance performances following bilateral olfactory bulbectomy

Three experiments were performed to study the effects of bilateral olfactory bulbectomy upon active and passive avoidance conditioning. In the first experiment, olfactory bulbectomized rats were found not to be impaired on a one-way active avoidance task but showed a fear retention deficit. In Experiment 2, sham-operated rats demonstrated a degree of fear retention that was a positive linear function of the number of shock presentations; olfactory bulbectomized rats showed a total absence of fear retention. In the third experiment olfactory bulbectomized rats failed to demonstrate the inverse relationship between shock intensity and two-way avoidance performance normally evidenced. The pattern of data obtained suggests that while bulbectomized rats do not show any general avoidance impairment they do seem to be unaffected by the suppressive effects of shock upon ongoing behavior.