Objective: To investigate brain activation and connectivity dynamics in individuals with idiopathic dystonia during motor tasks using Electroencephalography (EEG), Functional Magnetic Resonance (fMRI) and Functional Near-Infrared Spectroscopy (fNIRS).

Background: Research findings suggest abnormal brain connectivity in dystonia, the mechanisms underlying the malfunction in these networks are still not clear; multimodal neuroimaging may provide insights into this matter.

Method: Patients with idiopathic right upper limb dystonia and age-matched controls were assessed during the finger-tapping and writing tasks. Functional images were acquired in a 3.0 T MRI equipment, a portable 8×8 fNIRS system and a 32-channel EEG. EEG and fNIRS were acquired simultaneously.  With EEG, we applied power spectrum analyses considering the mu and beta rhythms of the motor cortex, and analyzed complex networks and microstates.

Results: Patients’ fMRI showed increased activation in the right cerebellar lobules (V and Vl) during the right-hand finger-tapping. Power spectra analysis showed that patients had a loss of event-related desynchronization (ERD) of the mu rhythm under this condition. Patients also showed decreased activation of in left frontal cortex, ipsilateral and medial somatosensory areas (fNIRS). During the writing task, patients had increased activation in left somatosensoial cortex and the loss of desynchronization of beta rhythm. We observed differences in the structure of the connective core in the beta rhythm, as well as in the intensity of the patients’ hubs. Abnormalities were also identified in microstates of the patients’ default mode network.

Conclusion: In dystonia, increased or decreased brain activation may be task-dependent, as shown by the contrasting results during finger-tapping and writing. Patients did not present the expected ERD in both motor tasks, suggesting changes in their intracortical inhibition mechanisms. The cerebellum may be a relevant node to further investigate in dystonia, although we cannot determine whether cerebellar disparities are compensatory or disease-causing.

« Back to MDS Virtual Congress 2020

MDS Abstracts - https://www.mdsabstracts.org/abstract/multimodal-neuroimaging-during-motor-tasks-in-upper-limb-dystonia/