ANATOMICAL ORGANIZATION OF SEPTAL PROJECTIONS IN MAINTENANCE OF DRL BEHAVIOR IN RATS

Placed lesions in tracts associated with the septum to assess their contributions to decrements observed on differential reinforcement of low rates of responding following large septal lesions. Ss were 38 male Long-Evans hooded rats. Septal and large fornical lesions, which disrupted both dorsal fornical and fimbrial fibers, produced marked deficits. However, smaller lesions restricted to the medial aspects of the fornix, sparing the fimbria, had little effect. Lesions of the stria medullaris produced less severe deficits which were more transient than those found after the other lesions. Results suggest that septal connections with fields CA 3 and 4 of the hippocampus via the fimbria form a major component of a system important in response inhibition and timing behavior. The rostral field CA 1 and associated fibers in the dorsal and postcommissural fornix were not implicated in such an inhibitory function. (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.