Simple and configural association learning in rats with bilateral quisqualic acid lesions of the nucleus basalis magnocellularis

• Published in: Behavioural brain research 1997-12, Vol.89 (1), p.71-85
• Main Authors: Butt, Allen E, Hodge, Gordon K
• Format: Article
• Language: English
• Subjects: Acetylcholine; Acoustic Stimulation; Alzheimer's disease; Anatomical correlates of behavior; Animals; Association Learning - physiology; Basal forebrain; Basal Ganglia - pathology; Basal Ganglia - physiology; Behavioral psychophysiology; Biological and medical sciences; Cholinergic; Conditioning, Operant - physiology; Configural association theory; Discrimination (Psychology) - physiology; Excitatory Amino Acid Agonists - toxicity; Extinction, Psychological - physiology; Fundamental and applied biological sciences. Psychology; Generalization, Response - physiology; Male; Memory; Photic Stimulation; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Quisqualic Acid - toxicity; Rats
• ISSN: 0166-4328; 1872-7549
• DOI: 10.1016/S0166-4328(97)00062-4

We hypothesized that bilateral quisqualic acid lesions of the nucleus basalis magnocellularis (NBM) in rats would impair configural but not simple association learning. In experiment 1, rats were tested in a negative patterning operant discrimination where they were food-reinforced for responding to a light or a tone (L +, T +) but not for responding to the configural stimulus consisting of the light and tone presented simultaneously (LT −). Consistent with our hypothesis, NBM-lesioned rats showed a transient but significant impairment, responding normally to L + and T + but responding more often to LT −, in addition to responding more often during the inter-trial interval (ITI) than controls. In experiment 2, rats were tested in a simple operant discrimination where rats were food-reinforced for responding to a light (L +) but not for responding to a tone (T −). Although NBM-lesioned rats again responded normally to L + as predicted, NBM-lesioned rats were transiently impaired, making more T − responses and more ITI responses than controls. Together, these results suggest that the NBM is involved in both configural and simple association learning but that this involvement is limited to learning to withhold responding to non-reinforced contextual or discrete stimuli. Finally, rats from experiment 2 underwent extinction trials, where results showed no difference between NBM-lesioned and control groups, suggesting that the NBM is not involved in the extinction of conditioned responding to previously reinforced stimuli.