Somatosensory timing and cerebellar-basal ganglia beta-band interactions in Parkinson’s disease
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Background
Parkinson’s disease (PD) has traditionally been viewed through the lens of basal ganglia dysfunction, yet emerging research also implicates the cerebellum and its connections to the basal ganglia.
Objective
To investigate cerebellar and basal ganglia beta-band responses during a somatosensory timing task, with a focus on prediction- and evaluation-related activity in individuals with PD compared to controls.
Methods
Using magnetoencephalography (MEG), we presented participants with tactile stimuli in regular (non-jittered) and irregular (jittered) sequences. In each trial, the final expected stimulus was omitted to probe prediction-related activity before the omission and evaluation-related activity after it. We analyzed beta-band responses and functional connectivity across cerebellum, basal ganglia, thalamus, and motor cortex.
Results
We found prediction-related differences between PD and controls in cerebellum and basal ganglia before the omissions, but no differences between PD and controls in the cerebellar evaluation responses after the omissions. In PD participants, basal ganglia activity favored jittered sequences over non-jittered, whereas the reverse was seen in the controls. Moreover, alterations in cerebellar beta-band responses correlated with symptom severity in PD participants. Finally, we found an interaction in functional connectivity within a sensory-integration network between the two participant groups and the regularity of the stimuli.
Conclusion
We interpret these findings as indicating that the cerebellum may play a compensatory role in predictive timing in PD and that in challenging conditions, the jittered condition, the wider sensory-integration network is harder at work in PD in trying to predict upcoming stimuli.
