EEG coherence analysis in subjects after rehabilitation from stroke with motor imagery

Abstract

Stroke is caused by a lack of blood supply in a particular region of the brain that may be a consequence of clot formation or rupture of the blood vessel. It presents high incidence, generating permanent neurological sequelae, which leads to motor impairment and functional limitations. It is necessary to identify techniques of motor rehabilitation that favour the cortical reorganization and the functional recovery of affected individuals. Motor imagery (MI) is a technique used in motor rehabilitation of individuals with motor deficit, defined as mental simulation of movements without movement actually occurring. MI activates the same cortical regions as the execution of the movement, especially the motor area and the somatosensory cortex. The objective of this study was to investigate changes in cortical activity related to MI rehabilitation (during 1 month—three session/week) in hemiparetic individuals after stroke. EEG signals from eight post-stroke individuals were registered one week before MI rehabilitation (BMI) and 1 month after rehabilitation (Follow-up), during motor task execution (MOV) and motor task imagination (IMG). Magnitude squared of coherence (MSC) was evaluated, using 50 epochs of the EEG signal considered without artefact. The delta band presented the highest MSC values in both conditions (MOV and IMG), mainly in frontal and central regions. Only two volunteers presented MSC values in the Follow-up period higher than in the period before mental rehabilitation, mainly on electrodes F3 (p = 0.04), C3 (p = 0.036) and F4 (p = 0.02).