Presentation Information
[P1-04]Neuronal signals in the primate cerebellum underlying the detection of rhythmic deviations
*Masashi Kameda1, Masaki Tanaka1 (1. Hokkaido university graduate school of medicine (Japan))
Keywords:
Rhythm,Prediction,Non-human primate,Cerebellum
When we are feeling the rhythm, we often notice any subtle deviation. This ability relies on accurate prediction of periodic event timing. The cerebellum, known for its role in motor control, is also implicated in sensory timing prediction. Previous studies in our lab showed that neurons in the cerebellar dentate nucleus (DN) exhibit periodic firing modulation during the missing oddball detection task, in which animals were required to detect omissions of regularly presented visual stimuli (Ohmae et al., 2013). These neurons also showed greater directional modulation by stimulus location, suggesting a role in sensory rather than motor processing (Kameda et al., 2023). However, it remains unclear whether they contribute to the detection of subtle rhythmic deviations independently of movement.To address this point, we trained monkeys to detect slight changes in rhythm and examined the relationship between their behavioral performance and the activity of DN neurons. In the modified oddball detection task, a slightly longer interstimulus interval was introduced within a series of visual stimuli presented at regular 400-ms intervals. Monkeys were rewarded for responding with a hand movement to either a delayed stimulus (Hit) or subsequent omission (Miss). During recording sessions in two monkeys, we presented delays of 60–160 ms and compared neuronal activity between Hit and Miss trials. The firing rate immediately before the delayed stimulus was significantly greater in Hit than Miss trials (paired t-test; p < 10–7, n = 37), while the activity at the time of the preceding stimulus showed no difference (p = 0.65). We also optogenetically manipulated neuronal activity in the DN to elucidate its causal role in behavior. After expressing ChR2 specifically in Purkinje cells of the cerebellar clus lobules, we illuminated their terminals within the DN to suppress neuronal activity. Optical stimulation immediately before the delayed stimulus significantly reduced Hit rate for delays that originally produced a Hit rate between 30% and 70% (p < 0.05, n = 23). These findings suggest that periodic neuronal activity in the DN encodes sensory timing predictions and contributes to the detectability of rhythmic deviations.