Although there is evidence to suggest that the retrosplenial cortex is involved in spatial learning and memory, many lesion studies have left the more caudal part of this region intact so leaving its role untested. In the first experiment, rats with neurotoxic lesions of the caudal half of the retrosplenial cortex (RspC1) were tested on a reference memory task in the water-maze. The RspC1 anima...

Six maze-experienced hooded rats were timed during five trials on which they collected water from all arms of an eight-arm radial maze, then made five more choices. All subjects frequently exhibited a "task-completion pause:" The subjects rarely spent more than 1 sec in the center of the maze between choices until they had entered all eight arms, then stopped in the center of the maze. In contr...

Anecdotal observations of the behavior of rats with a vitamin K-deficiency suggested that this deficiency was associated with hypoactivity, general malaise, and a lack of exploratory behavior. These observations were pursued by assessing locomotor activity in a circular photocell-monitored track, open-field activity, and radial-arm maze performance in rats rendered vitamin K-deficient by dietar...

The behavior of rats white solving a 12-arm radial maze was investigated using measures of response bias, choice latencies, and behavioral organization. Response bias decreased as a function of choice number, while the amount of time spent on the center platform between choices increased substantially during the last few choices. This increase in time between choices was largely accounted for b...

The radial-arm maze is an established method for testing an animal's spatial win-shift behavior. Research on mammals, birds, and fish has shown that the mastery of this task is commonly mediated, to different degrees, by two types of strategy: those based on external cues and those based on response stereotypy. In the present study we trained four red-footed tortoises (Geochelone carbonaria) to...

The present study provides the 1st report on the effects of selective lesions of the dysgranular portion of the retrosplenial cortex in rats. Excitotoxic lesions of the dysgranular area were sufficient to impair behavior in the radial-arm maze by biasing the strategy used to solve the task. In particular, rats with dysgranular retrosplenial lesions were less reliant on distal visual cues to con...

This research reports the effects of two metabolic groups of bacteria on physiological activity and cognitive function in C57BL/6 mice. In one experiment, the mice on a diet supplemented with red kidney bean for 24 hr were able to complete an eight-arm radial learning maze in a shorter time than mice on a diet without red kidney beans. The median time required for mice to complete the maze when...

Rats experienced a spatial pattern of baited and unbaited arms in an eight-arm radial maze. The spatial pattern remained constant over trials, but the spatial locations that were baited varied unpredictably. Although there was no evidence of control by the spatial pattern during free choice training trials, the rats' ability to locate baited arms in forced choice test trials was superior to tha...

We examined the effects of long-term adrenalectomy (ADX) on hippocampal anatomy and behavioral learning in two spatial memory tasks. We assessed damage throughout the hippocampus by stereological analysis of the dentate gyrus and Ammon's horn. Rats were ADX or sham operated, and then tested in the Morris water maze 12 weeks after surgery, followed by testing on an eight-arm, alternating-baited ...