title: Real-time dopamine measurement in awake monkeys.
abstract: Fast-scan cyclic voltammetry (FSCV) is often used to measure real-time dopamine (DA) concentrations in awake, behaving rodents. Extending this technique to work in monkeys would provide a platform for advanced behavioral studies and a primate model for preclinical research. The present study demonstrates the feasibility of DA recordings in two awake monkeys (Macaca mulatta) using a mixture of techniques adapted from rodent, primate and brain slice work. We developed a long carbon fiber electrode to operate in the larger primate brain. This electrode was lowered into the striatum each day using a recording chamber and a detachable micromanipulator system. A manipulator also moved one or more tungsten stimulating electrodes into either the nearby striatum or the ventral tegmental area/substantia nigra pars compacta (VTA/SNc). We developed an electrical stimulation controller to reduce artifacts during electrical stimulation. We also introduce a stimulation-based methodology for estimating distances between electrodes in the brain. Dopamine responses within the striatum were evoked by either stimulation of the striatum near the FSCV electrode, or stimulation within the VTA/SNc. Unexpected juice rewards also evoked dopamine responses in the ventral striatum. Thus, we demonstrate that robust dopamine responses can be recorded from awake, behaving primates with FSCV. In addition, we describe how a stimulation technique borrowed from the neuroprosthetics field can activate the distributed monkey midbrain dopamine system in a way that mimics rodent VTA stimulation.
authors.affiliation: Laboratory of Neuropsychology, Division of Intramural Research, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Erik W
authors.initials: EW
authors.lastname: Schluter
authors.affiliation: Laboratory of Neuropsychology, Division of Intramural Research, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Mitz
authors.affiliation: Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Cheer
authors.affiliation: Laboratory of Neuropsychology, Division of Intramural Research, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Bruno B
authors.initials: BB
authors.lastname: Averbeck
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism / Q000502:physiology*; D046690:Deep Brain Stimulation / Q000295:instrumentation / Q000379:methods; D004298:Dopamine / Q000378:metabolism*; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods*; D005071:Evoked Potentials; D008253:Macaca mulatta; D008297:Male; D012201:Reward; D014851:Wakefulness
chemical_list: D004298:Dopamine