Neuro-Intermuscular Coordination Enhancement (NICE) Rehabilitation Through Human-Machine Interaction in Chronic Stroke

Motor impairment after stroke will be measured by upper extremity FMA (UE-FMA). The maximum UE-FMA motor score is 66 (i.e., 0: complete motor impairment; 66: normal motor performance). Each item is scored on a 3-point scale (0 = cannot perform, 1 = performs partially, 2 = performs fully). The FMA score reflects the level of upper extremity motor impairment.

Surface EMGs will be recorded from 8 key arm muscles during a 54-target isometric force generation task. A dimensionality reduction method (non-negative matrix factorization (NNMF)) will be applied to identify intermuscular coordination patterns - operational definition of motor modules in the field of motor neuroscience. They are mathematically 8-dimensional unit vectors. Similarity score is the scalar product (or dot product) between a pair of intermuscular coordination patterns in comparison (i.e., motor modules). We compute the similarity score between the less-affected and the more-affected arms. Also, surface EMGs will be recorded from 8 key arm muscles during 3D dynamic reaching tasks. NNMF will be applied to EMGs to identify and compare intermuscular coordination patterns. Similarity score is the scalar product between motor modules (i.e., intermuscular coordination patters) of the more-affected arm in stroke group and dominant arm in healthy group.

Kinematic synergies are a representation of multi-joint coordination. It will be identified using NNMF algorithm applied to the joint kinematic data obtained from 3D dynamic point-to-point reaching tasks. Kinematic synergy similarity between stroke and healthy will be calculated using their scalar product.

Pairwise joint angle-to-angle correlation is a way to see the joint coupling using kinematic data. It will be calculated using Pearson's correlation coefficient between joint angles during the point-to-point reaching task.

The active range of motion will be calculated from full active range tasks for shoulder flexion/extension, internal/external rotation, abduction/adduction, elbow flexion/extension, and wrist pronation/supination. Kinematic joint positions and angles will be used to calculate the same.

EEG-derived spectral power ratios will be calculated, in resting and task conditions, across different frequency bands (delta, theta, alpha, beta, gamma) and different events (onset, successful match, etc.) across four different directions of target match.

The revised brain symmetry index with EEG signals will be computed in the resting state during eyes open and closed conditions.

Functional connectivity using a directed transfer function will be computed to identify the information flow and coherence among EEG and EMG signals in the desired brain region and muscle activation associated with directional 4-target isometric force generation.

Functional connectivity using a directed transfer function will be computed to identify the information flow and coherence among EEG signals from different regions of interest (sources, e.g., ipsi and contralesional fronto-parietal regions, primary motor cortex and somatosensory cortices).

Recruitment rate will be calculated as the number of participants enrolled per month during the recruitment period. This is a feasibility outcome.

Intervention adherence will be calculated as the percentage of scheduled intervention sessions completed by each participant. This is a feasibility outcome.

Participant tolerance will be measured as the number and percentage of participants who complete intervention sessions without stopping due to discomfort, fatigue, pain, or other intolerance-related reasons. This is a feasibility outcome.

Intervention fidelity will be calculated as the percentage of intervention sessions delivered according to the study protocol. This is a feasibility outcome.

Dose equivalence will be assessed by comparing total intervention dose between groups, measured as total minutes of training and/or number of completed sessions per participant. This is a feasibility outcome.

NICE-specific feasibility will be assessed as the percentage of NICE intervention sessions in which the NICE training system/protocol is successfully implemented as intended. This is a feasibility outcome.

Retention rate will be calculated as the percentage of enrolled participants who complete each scheduled follow-up assessment. This is a feasibility outcome.

Successful data acquisition will be calculated as the percentage of expected EMG, EEG, kinematic, and clinical outcome datasets successfully collected and usable for analysis. This is a feasibility outcome.

The gross manual dexterity and upper extremity coordination will be assessed through BBT, which involves transfer of blocks from one compartment of a box to the other within 60 seconds. The score is the number of blocks successfully transferred to the other side within 60 seconds.

The increase in muscle tone will be assessed through MAS around the elbow and shoulder. MAS score ranges from 0 to 5. The MAS score reflects the severity of muscle spasticity.

Motor function will be assessed through WMFT, which evaluates both the time and quality of performance across 17 tasks that range from simple joint movements to complex functional activities (like lifting a can or folding a towel). Performance Time (sec) is measured, with a maximum time limit (usually 120 seconds). Functional Ability Scale rates the quality of movement, using a 6-point ordinal scale (0 = Does not attempt with the involved arm, 1 = Attempted but cannot complete task, 2 = Completes task with great difficulty or poor movement quality, 3 = Completes task with moderate difficulty or noticeable impairment, 4 = Completes task with minor difficulty or near-normal movement, 5 = Normal movement quality and speed). The WMFT score assesses upper extremity motor function.