Influence of myelo-architectures on direct cortical response evoked by electrical stimulation

Cyto-myelo architecture vary across brain regions, particularly between primary areas (motor M1, sensory S1), the premotor cortex and the more associative areas such as the Broca, Wernicke, and other association areas. Due to the specific characteristics of electrical stimulation, these architectural variations should be reflected in cortical responses evoked by direct electrical stimulation (DES). We sought to test this hypothesis.

DES was administered directly to different regions of the cortex while recording DCRs (direct cortical responses) in 10 patients. The shapes of the first components P0 and N1 of the signals were analyzed.

The downward slope of the first component (P0) of the signal is statistically greater for responses recorded in precentral motor cortex and S1 than that of EPs recorded in more associative areas.

Precentral motor cortex and S1 are distinguished by the presence of larger diameter, heavily myelinated fibers. These anatomical features explain the response and the increased slope of the P0 component in these regions, compared to associative areas.

The first component of DES-evoked responses reflects myelo architecture in particular. This could form the basis of an electrodiagnostic method using the evoked response.