The effect of previous experience upon operant performance following cerebellar lesions in the rat

Abstract

Lesions of the fastigial nuclei and cerebellar vermis, but not lesions of the dentate nuclei, were found to produce marked performance deficits on a differential reinforcement of low rates (DRL) schedule of reinforcement. This deficit was characterized by an abnormal number and distribution of responses within the schedule interval. Lesions, however, did not produce a deficit following preoperative training or when subjects were tested on a fixed-interval (FI) schedule. In addition, when DRL and FI performance was contrasted, all subjects were responsive to schedule contingencies. Results suggest that the DRL deficit following cerebellar lesions is due to a tendency to perseverate in response strategies, and is not related to a global disruption of timing or a pervasive inability to suppress responding.

Effects of lesions to the cerebellar vermis and hemispheres on timing and counting in rats.

“…Sensitivity to time in Part 1 was the same for cerebellar hemisphere, vermis, and sham groups and was extremely stable across presurgery and both postsurgery test sessions. These findings are consistent with previous animal studies that report no apparent deficits in temporal discrimination following lateral cerebellar lesions for durations greater than 15 s (Clarke et al, 1996; Kirk, 1985).…”

“…As yet, remarkably little animal work suggests that the cerebellum plays an important role in temporal discrimination. Perrett and colleagues (Perrett & Mauk, 1995; Perrett, Ruiz, & Mauk, 1993) reported a timing impairment for the nictitating membrane response (NMR) in the rabbit following lesions to the lateral cerebellum with interstimulus intervals ranging from 150 to 1,000 ms. Kirk (1985) found that rats with lesions of the fastigial nucleus and cerebellar vermis showed marked deficits when trained on a differential reinforcement of low rates of responding schedule (DRL 20 s). However, this DRL effect does not appear to reflect a general timing deficit because the rats continued to show appropriate and accurate responding on an explicit timing task, a fixed interval schedule (FI20); rats with lesions to the dentate nucleus were not impaired on either task.…”

“…One alternative to the milliseconds timer hypothesis is that the cerebellum is part of a distributed set of neural structures collectively responsible for timing over an extended temporal domain, from milliseconds to several minutes. To account for the animal and human evidence that cerebellar damage usually produces deficits for interval timing in the milliseconds range but not for durations outside this range (>8 s; Clarke et al, 1996; Ivry & Keele, 1989; Kirk, 1985; Nichelli et al, 1996), we offer instead a constant variability hypothesis, which states that damage to the cerebellum adds constant variability to the sensitivity of timing. Constant variability refers to variability that is the same at all levels of another variable, such as a sensory noise, that may always be present in sensory discrimination irrespective of stimulus magnitude (Getty, 1975).…”

Role of an enriched environment on the restoration of behavioral deficits in Lurcher mutant mice

“…In the present study, mice of both groups had many more open arm entries than in the previous one, probably caused by differences in environmental conditions such as the intensity of room illumination, maze positioning, and maze dimensions. The increased entries and duration of open arm visits by Lurchers may be ascribed to a decrease in behavioral inhibition, as has been found with cerebellar-damaged animals on other tasks, such as spontaneous alternation (Lalonde et al, 1986), differential reinforcement of low rate (Kirk, 1985), and successive discrimination learning (see Watson, 1978).…”