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Hirokane K, Nakamura T, Kubota Y, Hu D, Yagi T, Graybiel AM, Kitsukawa T. Emergence of rhythmic chunking in complex stepping of mice. iScience 2023; 26:106765. [PMID: 37216111 PMCID: PMC10196557 DOI: 10.1016/j.isci.2023.106765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 03/17/2023] [Accepted: 04/24/2023] [Indexed: 05/24/2023] Open
Abstract
Motor chunking is important for motor execution, allowing atomization and efficiency of movement sequences. However, it remains unclear why and how chunks contribute to motor execution. To analyze the structure of naturally occurring chunks, we trained mice to run in a complex series of steps and identified the formation of chunks. We found that intervals (cycle) and the positional relationship between the left and right limbs (phase) of steps inside the chunks, unlike those outside the chunks, were consistent across occurrences. Further, licking by the mice was also more periodic and linked to the specific phases of limb movements within the chunk. Based on these findings, we propose the rhythm chunking hypothesis, whereby within chunks, the repetitive movements of many body parts are linked by the rhythm parameters: cycle and phase. The computational complexity of movement may thereby be reduced by adjusting movements as the combination of rhythms.
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Affiliation(s)
- Kojiro Hirokane
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Toru Nakamura
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Yasuo Kubota
- McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Dan Hu
- McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Takeshi Yagi
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Ann M. Graybiel
- McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Takashi Kitsukawa
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
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Neural signals regulating motor synchronization in the primate deep cerebellar nuclei. Nat Commun 2022; 13:2504. [PMID: 35523898 PMCID: PMC9076601 DOI: 10.1038/s41467-022-30246-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 04/21/2022] [Indexed: 11/09/2022] Open
Abstract
Movements synchronized with external rhythms are ubiquitous in our daily lives. Despite the involvement of the cerebellum, the underlying mechanism remains unclear. In monkeys performing synchronized saccades to periodically alternating visual stimuli, we found that neuronal activity in the cerebellar dentate nucleus correlated with the timing of the next saccade and the current temporal error. One-third of the neurons were active regardless of saccade direction and showed greater activity for synchronized than for reactive saccades. During the transition from reactive to predictive saccades in each trial, the activity of these neurons coincided with target onset, representing an internal model of rhythmic structure rather than a specific motor command. The behavioural changes induced by electrical stimulation were explained by activating different groups of neurons at various strengths, suggesting that the lateral cerebellum contains multiple functional modules for the acquisition of internal rhythms, predictive motor control, and error detection during synchronized movements.
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