Timing behavior in streptozotocin-induced diabetic rats.

Abstract

There is evidence of deterioration of spatial cognition in streptozotocin (STZ)-induced diabetic rats. Here, we evaluate a possible dissociation in the cognitive deficits due to diabetes by examining another crucial aspect of animal cognition: temporal perception. Timing behavior and temporal memory were evaluated in STZ-induced diabetic rats employing two timing tasks: the peak-interval procedure, with its Gap variant, and the interval bisection task. A spatial memory task, rewarded alternation in the T-maze, was also evaluated to explore spatial cognition. The two timing tasks employed coincide in the finding of a normal timing performance in STZ-induced diabetic rats. The peak-interval procedure provided results that suggest that the timing behavior is equally accurate and precise than in control subjects; in the Gap procedure, an equal change in peak time in both groups indicates that temporal working memory is also intact. In the interval bisection task, we analyzed the acquisition of a temporal discrimination and the sensitivity to changes in the duration of the stimulus; no differences were found in either the acquisition process or the sensitivity index. In contrast, in the rewarded alternation task, STZ-induced diabetic rats exhibited a significant deficit in spatial cognition. The cognitive processes involved in timing behavior and temporal memory are not deteriorated as a consequence of diabetes; the cognitive deficits associated to diabetes thus seem to be restricted to the spatial domain.