Asymmetries in Cerebellar Activation during Finger Movements: A Functional Near-Infrared Spectroscopy Study

Resumé :
Introduction : The last decades have seen a tremendous increase of research about cerebellar functions. There is a series of theories – not necessarily mutually exclusive – regarding the cerebellum involvement in sensorimotor control supported by a wide range of cerebellar studies.

The heterogeneity of the findings encourages further investigations in cerebellar activation, especially hemisphere specificity, and calls for new techniques to allow easier routine assessment. We investigated the cerebellar hemispheres activation during finger movement of the dominant and sub-dominant hand with functional Near-Infrared Spectroscopy (fNIRS).

Material and Methods : One healthy subject performed a finger tapping task consisting of 6 repetitive blocks (task + rest) respectively for the left and right hand. The task was repeated twice for each hand changing the activity periods: first, 10 s of tapping followed by 30 s of rest; then, 20 s of tapping followed by 30 s of rest. Cerebellar responses for each repetition were time-locked averaged.

Results : A similar hemodynamic response was observed ipsilaterally and contralaterally for both tasks (10s vs 20s activity). The dominant hemisphere (right-handed subject) was involved even during the sub-dominant hand movement. A frequency domain analysis showed higher synchronization of the right hemisphere for left hand movement.

Discussion/Conclusion : fNIRS proved to be a good technique to capture cerebellar hemodynamics in a non-clinical setting. The asymmetries in cerebellar activation agree with previous fMRI studies. They suggest the existence of different layer of controls from the cerebellum in the two hemispheres: one for precise movements and the other for repetitive ones.

Mots clés : cerebellum, fNIRS, hemispheric specialization

Auteurs : Giulia Rocco, Jerome Lebrun, Olivier Meste, Marie-Noele Magnié Mauro

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