Rationale: Parkinson's disease patients with deep brain stimulation electrodes represent a unique opportunity to study the influence of basal ganglia on neurocognitive function. Intervention: Patients' deep brain stimulators will be turned off or on and the frequency will be changed to either theta or gamma. Objectives: To identify differences in higher cognitive functions with stimulation "on" and "off" and theta versus gamma frequency stimulation. Study population: 12 patients who had previously undergone bilateral STN deep brain stimulation implantation. Study methodology: Patients will undergo four sessions of neuropsychological testing (RNGT, verbal fluency, D-KEFS CWIT) at baseline, no stimulation, theta stimulation and gamma stimulation, in random order over one day. Study outcomes: Test results of RNGT, verbal fluency, D-KEFS CWIT. Follow-up: none Statistics: Test results will be analyzed using within-subjects statistical tests.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
12
Stimulation of existing DBS device at 100Hz, with other parameters at baseline
Stimulation of existing DBS device at 130Hz, with other parameters at baseline
Existing DBS device turned off
Keck hospital of the University of Southern California
Los Angeles, California, United States
Delis-Kaplan Executive Function System Verbal Fluency
Number of words per category in one minute
Time frame: 5-15 minutes following stimulation frequency setting change.
Delis-Kaplan Executive Function System Color Word Interference Task
Time to completion of a color-word interference task
Time frame: 5-15 minutes following stimulation frequency setting change.
Random Number Generation
Listing of 100 numbers at 1 Hz in a random order. Evan's RNG: a measure of disproportion with which one number follows another in a sequence. Scores range from 0 (equal proportion of sequence pairs) to 1 (maximum disproportion of sequence pairs). A higher score indicates a lower randomness and poorer exective function. Count score 1: a measure of propensity to count in steps of 1. The length of each sequence with steps of 1 is squared. The total of these is summed. Scores range from 0 (no sequences with steps of 1) to 100000 (all sequences with steps of 1). A higher score indicates lower randomness and poorer exective function. Count score 2: a measure of propensity to count in steps of 2. The length of each sequence with steps of 2 is squared. The total of these is summed. Scores range from 0 (no sequences with steps of 2) to 100000 (all sequences with steps of 2). A higher score indicates lower randomness and poorer exective function. Evan's RNG, count score 1 and cou
Time frame: 5-15 minutes following stimulation frequency setting change.
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