The cerebellum is well-established in sub-second motor timing, but its role in supra-second interval timing remains unclear. Here, we investigated how cerebellar output influences time estimation over longer timescales. Male rats performed a nose-poke interval timing task in which reward availability could be predicted either from a fixed 2.5 s auditory cue (cued trials) or had to be estimated internally during uncued 3.5 s trials that demanded self-timing. Chemogenetic inhibition of the lateral cerebellar nucleus produced bidirectional effects: delayed action initiation in predictable trials and premature (∼100-160 ms) responses when self-timing was required. Despite a slowing of movement, overall task success rates remained unchanged. Because motor slowing is likely to lead to later, not earlier, action initiation, these results implicate the lateral cerebellar nucleus in computing internal time estimates. These findings demonstrate that the cerebellum integrates motor and cognitive processes for supra-second timing, with differential effects on externally guided and self-generated timing. Significance Statement The cerebellum, a brain region best known for fine-tuning movements with sub-second accuracy, may also be involved in judging longer time intervals. Rats were trained on an interval timing task where supra-second auditory tones signaled either a predictable cue or unpredictable cue that required estimating time that was dependent on self-timing. By reversibly inhibiting lateral cerebellar output we show that rats misjudge time over seconds, either over or underestimating time depending on whether they rely on an external cue or on self-timing. Locomotor slowing was modest and success rates were preserved, dissociating temporal estimation from execution deficits. The findings are therefore consistent with the cerebellum contributing to both sub-second motor and supra-second cognitive self-timing processes.
Boven et al. (Thu,) studied this question.