Neuroanatomical Variation Research Articles

Differential olfactory bulb contributions to baitshyness and place avoidance learning

Garcia and Ervin [14] hypothesized that neuroanatomically discrete associative mechanisms subserve illness-induced taste aversions and shock-motivated avoidance of telereceptive cues. Such neuroanatomical diversity implies that appropriately placed brain lesions might selectively influence one of these types of learning. While several limbic-system lesions can disrupt shock-motivated compartment avoidance (SMCA) without modifying illness-induced taste aversion (IITA) conditioning, the opposite pattern of selective interference has not been reported. The anterior tips of the olfactory bulbs of male albino rats were removed because neuroanatomical and behavioral data indicated that these lesions might disrupt IITA without influencing SMCA. Larger olfactory-bulb ablations approximating total bulbectomies were also studied for comparison purposes. Both total bulbectomies and anterior bulbectomies partially blocked IITA acquisition. Total bulbectomies also interfered with SMCA conditioning, but this learning was unimpaired by anterior bulbectomies. These anterior-bulbectomy results are consistent with the neuroanatomical-diversity hypothesis. Present findings are also discussed relative to the applied problem of selecting biologically appropriate noxious stimuli for aversion therapy approaches to alcoholism treatment.