Estimation of Cognitive State Improvement using EEG Brain Imaging after TDCS Stimulation Therapy

Abstract

Brain is the most important organ in human body. The effects of brain impairment are wide ranging and includes cognition, fatigue, sleep issues, headaches, dizziness, impaired self-awareness, clinical depression, attention and concentration problems, epilepsy, struggling in making decisions and many more. Brain rehabilitation via noninvasive techniques such as tDCS helps patients relearn functions and improvement in cognition, lost as a result of a brain impairment. Transcranial direct current stimulation (tDCS) is one such noninvasive, safe and convenient neuro-modulatory technique in neurological rehabilitation, treatment, and other aspects of brain disorders. The efficacy of tDCS in estimation of brain cognitive state improvement using changes in small electrical brain voltages recorded by Electroencephalogram (EEG) of 10 subjects is assessed by applying Event related De synchronization (ERDs) to Motor Imagery Period (MIP) and Rest Period (RP) of pre stimulation and post stimulation data and features extraction technique such as common spatial pattern (CSP).The results suggest a decrease of contralateral ERDs oscillatory activity related to an event as per the hypothesis in anodal post stimulation than pre stimulation across all channels for six subjects. Further Linear Discrimination Analysis (LDA) a machine learning model applied on CSP and ERDs proved that the classification accuracy between Motor imagery period (MIP) and Rest period (RP) after the stimulation therapy is higher than the Pre stimulation Motor Imagery period (MIP) and Rest period (RP).