| |
Abstract:
It is standard procedure in neurosurgery near motor cortex to
localize the functional division between motor and sensory cortex.
This division lies along the central sulcus, the anatomical
boundary separating the frontal and parietal lobes. Localization is
often done by intraoperatively recording somatosensory evoked
potentials from cortical surface electrodes. Advances in high
density ERP recording and inverse modeling may make it possible to
localize this boundary presurgically. We collected 128 channel
motor and somatosensory evoked potentials and whole-head MRI from a
normal volunteer. The MRI was segmented into 5 tissue-types (skin,
bone, cerebrospinal fluid, gray matter, white matter) with an
electrical conductivity estimate assigned to each tissue. We
created an anatomically accurate finite-element volume conductivity
head model from the segmented MRI. We computed a
"surface-to-surface" inverse in this model, calculating the
cortical field distribution from the scalp electrical field. The
lines of polarity inversion in the evoked potentials show the
functional division between motor and sensory cortex. This division
is presented on the cortical surface, showing the relation of the
functional and anatomical central sulcus.
|
