This study examines the relationship between a cerebral hemisphere and control of muscles on
the same side of the body (ipsilateral control). One good way to study this relationship is
to record electroencephalogram (EEG) activity directly from the cortical surface. Because
patients with epilepsy who are surgical candidates are already undergoing monitoring with
subdural and/or depth electrodes, they present an opportunity to study ipsilateral control.
Studying the electrocorticographic (ECoG) activity associated with simple voluntary movement
in such patients would not disturb ongoing monitoring of nearby areas of the brain, nor
would it endanger the patients.
Ten patients, who may be children or adults, will be recruited for this study. Brain
activity will be measured while they move the corner of their mouth and their fingers,
wrists, arms, and feet. The baseline measurements will be done with scalp electrodes. Once
subdural electrodes have been placed, a second set of measurements will be done. Surface EMG
electrodes will be placed on the muscles whose movements are being tested. The tests will be
done on no more than 3 separate days, in sessions no longer than 2 hours, for each patient.
A corticomuscular functional relationship has been well addressed in the literature in terms
of the control exerted by the primary motor region of the cerebral cortex over the
contralateral extremities (Mima and Hallet 1999). However, the relationship between a
cerebral hemisphere and ipsilateral motor control is not well understood. We hypothesize
that a cortical motor control region ipsilateral to the extremities is located in Brodmann's
area 6. There are several methods that can be used to study this relationship in terms of
cortical region involved: coherence, correlation, and event-related desynchronization and
synchronization. Cortical EEG activity associated with contralateral limb activity or
stimulation usually is larger than that associated with ipsilateral limb activity.
Furthermore, activity over the scalp that is ipsilateral to motor activity is very small and
difficult to identify as compared with that occurring contralaterally. Recording responses
directly from the cortical surface would improve the ability to identify this activity. An
occasion that would allow us such an opportunity would be invasive monitoring in patients
Epileptic patients who are surgical candidates, but require more precise localization of
epileptogenic zones, typically undergo long-term video-EEG monitoring with subdural and/or
depth electrodes. Some patients may have seizure onsets close to the sensory-motor area of
the brain and require functional mapping in terms of motor function. We would like the
opportunity to study electrocorticographic (ECoG) activity associated with simple movements
in these patients who are undergoing invasive monitoring.
This study will not disturb ongoing monitoring, nor endanger the patient since no activation
or stimulation is involved.
PATIENTS UNDERGOING SUBDURAL IMPLANTATION:
Epileptic patients who are undergoing invasive recording with implanted subdural
electrodes that cover the sensorimotor cortices.
Therefore, we will recruit only those patients with medically intractable epilepsy who are
candidates for surgical treatment, and in whom invasive monitoring was deemed necessary
for the purpose of precise localization of epileptogenic zones.
Patients whose electrode implantation does not cover the sensorimotor cortices.