Using Parkinson's Disease to Study the Role of the Substantia Nigra Pars Reticulata

Parkinson's Disease (PD) is a movement disorder causing either uncontrolled movement,
slowness of movement, slowness of initiation of movement or rigidity of muscles. One method
of easing PD symptoms is the FDA-approved method of Deep Brain Stimulation (DBS) for patients
who no longer get effective treatment from the best available medication. The location in the
brain where the electrode is placed during DBS surgery for PD is called the Subthalamic
Nucleus or STN. During placement of the DBS electrode, the patient is awake and is asked to
do motor tasks to determine the correct placement in the STN and proper functioning of the
DBS electrode. This study aims to investigate another location in the brain, the Substantia
nigra pars reticulata or SNr, during the normal placement of the DBS electrode. This location
is also known to be involved in motor control of muscles and may be involved in the process
by which the initiation of movement occurs. The path through the brain to the STN used for
DBS surgery goes into the SNr but currently, no testing of the SNr is performed. We will
conduct a simple and well documented visual motor test to document the patient's stimulus
perception and motor intention both at rest and during neural stimulation of the SNr.

Inclusion Criteria:

- Clinical diagnosis of Parkinson's disease

- must be able to undergo awake surgery DBS

- must have unaided vision to view visual motor task

Exclusion Criteria:

- corrective eyeglasses or contact lenses