Mapping the Human Primary Somatosensory Cortex Using Dense-array EEG: An Analysis of the Somatosensory Evoked Potential

In principle, dense-array EEG (dEEG) technology has the ability to localize cortical brain activity with adequate spatial resolution such that anatomically and functionally distinct regions can be studied. The present study employs dEEG to map activity of the primary somatosensory cortex (SI), which is functionally and anatomically defined. EEG recordings were acquired from 10 participants as their thumbs were stimulated by a custom-made piezoelectric stimulator. Early components of the somatosensory evoked potential (SEP), which reflect activity from SI, were evaluated in individual participants to assess topographic distribution at the scalp. In a subset of participants, we build high-resolution electric head models that describe how current propagates from the cortex to the scalp surface, where the SEP is measured, and we use this model to localize the early SEP components. We report on the localization accuracy relative to the expected location (SI).