Effects of septal and caudate lesions were compared on brightness and spatial discrimination and reversal. Further analyses of the effects of these lesions and low-level electrostimulation of the septal area were made on a spatial-alternation problem. Septal lesions selectively impaired reversal of spatial, but not brightness, discrimination. Conversely, caudate lesions selectively disrupted brightness discrimination. Septal lesions, in contrast to septal stimulation or caudate lesions, blocked acquisition of spatial alternation and generally induced faster performance time. These results provide evidence of at least two dissociable dysfunctions associated with septal lesions. Further dissociation of septal and caudate functions is indicated, but the data do not rule out some commonality of operation.

Adult mice were administered the common parasite Toxocara canis or lead or both. The parasite clearly altered mouse performance on tests of exploration, activity, learning, and motor coordination; behavioral effects in mice receiving lead alone were less general. Consequence of Toxocara administration appeared attenuated in animals receiving both agents. Parasite larvae were found in the central nervous system in all infected mice.

When given the opportunity to control illumination, rats with septal lesions changed illumination conditions more often, but spent less total time in the light, than control animals. Therefore, compared with control rats, animals with septal lesions displayed both a greater preference for stimulus change and enhanced aversion for the illumination level used. A finding that such alterations in reactivity to light were maintained for 14 days was interpreted as being analogous to the effects of septal lesions on consumption of palatable and unpalatable fluids.