Research Program

We seek to understand the neural basis for specific signs and symptoms of brain network disorders, including Parkinson’s disease, isolated dystonia, essential tremor, and Huntington’s disease. Part of our effort is directed to identifying neural correlates of nonmotor symptoms, such as anxiety and depression, in addition to motor signs.

The general approach involves combined cortical and basal ganglia recording in humans. This research effort is complementary to our existing high-volume clinical program, in which approximately 80 new patients per year undergo placement of new deep brain stimulator (DBS) electrodes. Data gathered are used to confirm, refute, or expand upon existing models of basal ganglia and cortical function and dysfunction, to provide a better understanding of the mechanism of action of brain stimulation, and to improve the efficacy of DBS.

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Specific questions addressed are:

1) What brain circuit abnormalities underly specific motor and nonmotor features of movement disorders?

2) How do therapeutic interventions such as DBS normalize activity in the basal ganglia-thalamocortical network?

3) Can the efficacy and adverse effect profile of DBS be improved by incorporated feedback control? Can cortical signals be used to drive adaptive DBS?

Technical approaches

Acute intraoperative recording of cortical and basal ganglia local field potentials

During surgery for implantation of permanent DBS leads, temporary cortical strip electrodes (electrocorticography, ECoG) are introduced into the subdural space via the standard surgical exposure used for DBS implantation. Basal ganglia and cortical LFPs are recorded at rest, during computer-controlled movement tasks, and during acute therapeutic stimulation. Intraoperative CT is used in conjunction with structural MRI to accurately localize recording sites, and diffusion tensor imaging acquired preoperatively may be used to relate cortical findings to the anatomy of specific fiber tracts.

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Interictal electrocorticography in patients undergoing invasive video-ECoG monitoring

In human studies that involve placement of invasive electrodes, true normal control data are not available. However, ECoG data recorded in epilepsy patients, from cortical areas not involved with the epileptic focus, can be considered as a "control" group and be compared to subjects with movement disorders to provide insight into those patterns of brain activity that are specific to subjects with basal ganglia disease.

 

Chronic invasive brain recording

Recordings from a permanently implanted device that both delivers therapeutic stimulation and stores local field potentials (Medtronic Activa PC+S) then wirelessly transmits data used in our research studies.

 

Noninvasive electrophysiological analyses

This type of study uses scalp electroencephalography.