Oscillatory MEG motor activity reflects therapy-related plasticity in stroke patients

Abstract

Background: A goal of stroke rehabilitation is to harness the capacity of the brain to reorganize following neurological damage and enable restoration of function.

Objective: To understand how neural oscillatory motor responses change following a therapeutic intervention and to illuminate whether these neurophysiological alterations correlate with improvements on behavioral measurements.

Methods: Magnetoencephalography (MEG) was used to evaluate plasticity in motor networks following 2 weeks of intensive task-oriented therapy, which was paired with sham or peripheral nerve stimulation (PNS). Patients completed unilateral finger tapping before and 3 weeks after therapy as whole-head MEG data were acquired. MEG data were imaged using beamforming, and the resulting event-related synchronizations and desynchronizations (ERSs/ERDs) were subjected to region-of-interest (ROI) analyses. For each ROI, the authors compared the baseline and postintervention MEG response amplitude, volume, and peak location for premovement β ERD, movement-onset γ ERS, and postmovement β ERS.

Results: Following therapy, all patients showed reduced postmovement β ERS response amplitudes in bilateral precentral gyri and reduced γ ERS amplitudes in the precentral gyrus of the affected hemisphere. This latter response also distinguished treatment groups, as the posttherapy γ reduction was greater in patients who received PNS. Finally, both β and γ response amplitudes were significantly correlated with improvement on several behavioral indices of motor function.

Discussion: These case-series data indicate that oscillatory MEG responses may be useful in gauging plasticity in motor cortices following therapy in stroke patients.