title: Changes in GABA and glutamate concentrations during memory tasks in patients with Parkinson's disease undergoing DBS surgery.
abstract: Until now direct neurochemical measurements during memory tasks have not been accomplished in the human basal ganglia. It has been proposed, based on both functional imaging studies and psychometric testing in normal subjects and in patients with Parkinson's disease (PD), that the basal ganglia is responsible for the performance of feedback-contingent implicit memory tasks. To measure neurotransmitters, we used in vivo microdialysis during deep brain stimulation (DBS) surgery. We show in the right subthalamic nucleus (STN) of patients with PD a task-dependent change in the concentrations of glutamate and GABA during an implicit memory task relative to baseline, while no difference was found between declarative memory tasks. The five patients studied had a significant decrease in the percent concentration of GABA and glutamate during the performance of the weather prediction task (WPT). We hypothesize, based on current models of basal ganglia function, that this decrease in the concentration is consistent with expected dysfunction in basal ganglia networks in patients with PD.
authors.affiliation: Division of Neurosurgery, Seton Brain and Spine Institute Austin, TX, USA ; Department of Psychology, University of Texas at Austin Austin, TX, USA ; Department of Psychiatry, UT Southwestern Medical School Dallas, TX, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Buchanan
authors.affiliation: Department of Neurosurgery, University of Minnesota Medical School Minneapolis, MN, USA.
authors.forename: David P
authors.initials: DP
authors.lastname: Darrow
authors.affiliation: Department of Neurology, University of Utah School of Medicine Salt Lake City, UT, USA.
authors.forename: Kevin T
authors.initials: KT
authors.lastname: Meier
authors.affiliation: Department of Psychology, Department of Electrical and Chemical Engineering, Department of Kinesiology, Auburn University MRI Research Center, Auburn University Auburn, AL, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Robinson
authors.affiliation: Department of Psychology, VA San Diego Healthcare System, Research Service San Diego, CA, USA.
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Schiehser
authors.affiliation: Department of Psychiatry, Yale School of Medicine New Haven, CT, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Glahn
authors.affiliation: Division of Neurosurgery, Seton Brain and Spine Institute Austin, TX, USA ; Department of Psychology, University of Texas at Austin Austin, TX, USA ; Department of Cognitive Psychology, Eötvös Loránd University Budapest, Hungary ; NeuroTexas Institute, St. David's HealthCare Austin, TX, USA.
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Nadasdy
keywords: DBS; GABA; Parkinson disease; STN; WPT; glutamate; implicit memory; microdialysis