Investigating the measurement capability of densely-distributed subdermal EEG electrodes

This paper studies the effect of bipolar subdermal EEG lead placement on measurement sensitivity distributions. The electrodes were subdermally located on the skull of a realistic human head and arranged in a 5×5 matrix of electrodes located at the apex of the cranial vault. The effects on the measurement sensitivity were studied by means of the half-sensitivity volume (HSV). The results indicate that subdermal measurements focus the accuracy and specificity of EEG measurement; however, the size of the half sensitivity volume varies due to electrode location across one or more gyri, gray matter and cerebrospinal fluid (CSF) thickness. The results of the study suggest that subdermal needle electrodes could provide specific and accurate measurements of cortical activation but warrant further studies to understand how much the measurement sensitivity is influenced by placement of the subdermal electrodes over the gyri versus sulci.