Objective: To identify changes in effective (i.e. directed) connectivity in the executive motor network during finger tapping. To compare the effects of two rehabilitation strategies. 

Background: Current rehabilitation strategies for Parkinson’s disease (PD) include motor training (MOT) and motor imagery (MI). A more recent development is neurofeedback (NF) training during which patients are provided with real-time feedback  from motor regions involved in MI. The current study assessed the effect of NF + MOT vs MOT on the effective connectivity between motor regions during a motor task in PD patients.  

Methods: 26 PD patients had completed a 10-week randomized controlled trial that evaluated the clinical efficacy of real-time fMRI-NF training as described previously [1]. Briefly, patients were randomly assigned to one of two intervention groups matched for age, gender and medication. One group completed MI based NF combined with MOT (NF group), the other group completed MOT training only (MOT group) using a Nintendo Wiifit® machine. Before and after the intervention, both groups completed a visually cued right-hand finger tapping task “off” medication during which fMRI data were acquired. After quality control of fMRI data, scans from 21 early stage (Hoehn & Yahr stages I-III) PD patients (4/16/1, respectively) were included. Dynamic causal modelling (DCM) was applied to the fMRI data to estimate the effective connectivity between brain regions of the motor network involved in this task [2]. Bayesian Model Selection was used to determine which connectivity models best explained the data. 

Results: Network analyses revealed that in both the NF group and MOT group, global connectivity strength pre-post intervention has increased. Further, model comparison between pre-post intervention showed a change in the network structure for the NF group. The preferred model post intervention included new connections from primary motor area (M1) to the cerebellum and from M1 to the putamen. In contrast, no change in network structure was observed in the MOT group.

Conclusions: Both NF and MOT training led to increased connectivity between brain regions of the executive motor network. Further, changes in network structure were only observed in the NF group. Given that only the NF group showed significant clinical improvement as reported earlier [1], we suggest that NF can potentially enhance compensatory network organization in PD.

References: 1) Subramanian L, Morris MB, Brosnan M, Turner DL, Morris HR and Linden DEJ (2016). Functional Magnetic Resonance Imaging Neurofeedback-guided Motor Imagery Training and Motor Training for Parkinson’s Disease: Randomized Trial. Front. Behav. Neurosci. 10:111. doi: 10.3389/fnbeh.2016.00111

2) Friston KJ, Harisson L, Penny W (2003). Dynamic causal modelling. NeuroImage. (4): 1273–1302. doi:10.1016/S1053-8119(03)00202-7

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MDS Abstracts - https://www.mdsabstracts.org/abstract/modulation-of-executive-motor-network-after-neurofeedback-training-in-parkinsons-disease/