NEURAL CORRELATES OF BRADYKINESIA IN PARKINSON’S DISEASE: A KINEMATIC AND FMRI STUDY

Introduction

Bradykinesia is one of the cardinal signs of Parkinson’s disease (PD) and is usually assessed during repetitive movements [1, 2]. The aim of the study was to investigate the neural correlates of hand tapping performance in patients with PD relative to healthy controls.

Methods

Fifteen PD patients and 15 age- and sex-matched healthy controls were included. All the subjects underwent brain magnetic resonance imaging (MRI) including a hand tapping functional MRI (fMRI) task: subjects were asked to alternatively open and close (hand tapping) their right hand as fast and as ample as possible. Hand tapping speed and amplitude was measured during the fMRI task using an optical fiber data glove.

Results

During the fMRI hand tapping task, patients with PD showed reduced hand tapping amplitude and reduced activity of frontoparietal areas and sensorimotor regions including supplementary motor area (SMA), pre/postcentral gyri, pallidum and cerebellum compared to healthy controls. Decreased activity of SMA, cerebellum lobule VIII and caudate correlated with reduced hand tapping amplitude.

Discussion and Conclusion

As expected, patients with PD showed a worse hand tapping performance in terms of reduced movement amplitude relative to healthy controls. Interestingly, we found a correlation between bradykinesia and brain activity. In particular, areas strongly involved in motor planning such as SMA and caudate correlated with reduced movement amplitude. This study has the major strength of collecting objective motor parameters and brain activity simultaneously, providing a unique opportunity to investigate the neural correlates of bradykinesia in PD. A reduced recruitment of cortical, cerebellar and basal ganglia areas implicated in motor programming is a hallmark of bradykinesia in patients with PD. 

 

Funding: Italian Ministry of Health grant GR-2018-12366005

REFERENCES

[ 1 ] Prange-Lasonder GB, et al. European evidence-based recommendations for clinical assessment of upper limb in neurorehabilitation (CAULIN): data synthesis from systematic reviews, clinical practice guidelines and expert consensus. Journal of Neuroengineering and Rehabilitation. 2021. Doi: 10.1186/s12984-021-00951-y

[ 2 ] Holiga S, et al. Accounting for movement increases sensitivity in detecting brain activity in Parkinson’s disease. PLoS One. 2012. Doi: 10.1371/journal.pone.0036271

[ 3 ] Bologna M, et al. Neurophysiological correlates of bradykinesia in Parkinson’s disease. Brain. 2018. Doi: 10.1093/brain/awy155