Asymmetries in Cerebellar Activation during Finger Movements: A Functional Near-Infrared Spectroscopy Study
Résumé
* Introduction: Research about cerebellar functions has become a trendy field of study, especially regarding the cerebellum involvement in sensorimotor control. The heterogeneity of the findings encourages further investigations in cerebellar activation, hemisphere specificity, but also calls for new techniques to allow easier, cheaper routine assessments. In this study, we investigated hemispheric cerebellar activation during finger movements of the dominant and subdominant hand using functional near-infrared spectroscopy (fNIRS).
* Methods: One healthy right-handed subject performed a finger-tapping task consisting of six repetitive blocks (task + rest), respectively, for the left and right hands. The task was repeated twice for each hand changing the activity periods: first, 10 seconds of tapping followed by 30 seconds of rest; then, 20 seconds of tapping followed by 30 seconds of rest. Cerebellar responses for each repetition were time-locked averaged.
* Results: Similar haemodynamic responses were observed ipsilaterally and contralaterally for both tasks (10 vs 20 seconds activity). The dominant hemisphere (right-handed subject) proved to be involved even during subdominant hand movements. Higher synchronization of the right hemisphere for left-hand movement was observed and validated using frequency domain analysis.
* Conclusion: fNIRS proved to be a good technique to capture cerebellar haemodynamics in a non-clinical setting. Furthermore, the observed asymmetries in cerebellar activation fully agree with similar fMRI studies that suggest the existence of different layers of controls from the cerebellum in the two hemispheres.
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