Abstract TP158: Direct Path Functional Connectivity Changes in Stroke Survivors’ Brain Motor Areas Using a Brain Computer Interface Intervention for Upper Extremity Recovery

Abstract

Objective: This research seeks to identify changes in frequency specific directional flow of information transmission (functional connectivity) as a result of BCI intervention. Direct path functional connectivity (isolated effective coherence (iCOH)) changes between motor-related brain areas (Brodmann areas (BA) 1-7) are thought to relate to electrophysiological signatures of motor learning. Methods: N=16 right hemisphere stroke survivors participated in 9-15 sessions with the BCI. Participants executed hand movements prompted by visual cues on a monitor concordantly with the corresponding audio instructions (e.g., Left, Right, Rest). The ‘screening’ sessions (i.e. pre and post BCI intervention) contained two runs, each consisting of 15 trials for rest, left hand, and right hand movements (i.e., 5 trials for each of the three conditions, the order of trials in a run was random). iCOH is based on formulating a multivariate autoregressive model from time series measurements, and calculating the corresponding partial coherences after setting all irrelevant connections to zero, according to Pascual-Marqui et al. 2014. From the spectral density matrix (including Mu[8-12 Hz] and Beta[18-26 Hz] ranges) obtained from estimated signals in the selected ROI, the partial coherences between any pair of nodes can be calculated. The t-statistics was performed for iCOH values between post and pre of the impaired (left) hand movement trials and thresholded at p=0.05( t=2.13, uncorrected). Results: In the Mu band, iCOH decreased pre to post from contralesional BA 4 to ipsilesional BA 5 and increased from ipsilesional BA 4 to ipsilesional BA 6. In Beta band, iCOH decreased pre to post from ipsilesional BA 5 to contralesional BA 7 and increased from ipsilesional BA 4 and & contralesional BA 7 to ipsilesional BA 6 and also from ipsilesional BA 1,2,3 to contralesional BA 4. Conclusion: There is a consistent change in the direction of information flow, as measured by iCOH, toward the ipsilesional motor and pre-motor areas (BA 4,6). Significant iCOH increases are observed in both Mu and Beta from ipsilesional BA 4 to ipsilesional BA 6 suggesting an increase in participation of motor brain areas associated with motor planning and execution with participation in BCI intervention.