title: Dopaminergic stimulation facilitates working memory and differentially affects prefrontal low theta oscillations.
abstract: We used electroencephalography (EEG) together with psychopharmacological stimulation to investigate the role of dopamine in neural oscillations during working memory (WM). Following a within-subjects design, healthy humans either received the dopamine precursor L-Dopa (150 mg) or a placebo before they performed a Sternberg WM paradigm. Here, sequences of sample images had to be memorized for a delay of 5 s in three different load conditions (two, four or six items). On the next day, long-term memory (LTM) for the images was tested. Behaviorally, L-Dopa improved WM and LTM performance as a function of WM load. More precisely, there was a specific drug effect in the four-load condition with faster reaction times to the probe in the WM task and higher corrected hit-rates in the LTM task. During the maintenance period, there was a linear and quadratic effect of WM load on power in the high theta (5-8 Hz) and alpha (9-14 Hz) frequency range at frontal sensors. Importantly, a drug by load interaction--mimicking the behavioral results--was found only in low theta power (2-4 Hz). As such, our results indicate a specific link between prefrontal low theta oscillations, dopaminergic neuromodulation during WM and subsequent LTM performance.
authors.affiliation: Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
authors.forename: Cindy
authors.initials: C
authors.lastname: Eckart
authors.affiliation: Cognition and Brain Plasticity Group, University of Barcelona, Bellvitge Hospital, C/Feixa Llarga S/N, 08907 L'Hospitalet de Llobregat, Spain.
authors.forename: Lluís
authors.initials: L
authors.lastname: Fuentemilla
authors.affiliation: Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
authors.forename: Eva M
authors.initials: EM
authors.lastname: Bauch
authors.affiliation: Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; Department of Psychology, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany. Electronic address: n.bunzeck@uke.de.
authors.forename: Nico
authors.initials: N
authors.lastname: Bunzeck
mesh_terms: D000328:Adult; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology; D001931:Brain Mapping; D004298:Dopamine / Q000378:metabolism*; D015259:Dopamine Agents / Q000494:pharmacology; D059290:Dopaminergic Neurons / Q000187:drug effects / Q000502:physiology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007980:Levodopa / Q000494:pharmacology*; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008570:Memory, Short-Term / Q000187:drug effects / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology; D017397:Prefrontal Cortex / Q000187:drug effects / Q000502:physiology*; D013647:Task Performance and Analysis; D013826:Theta Rhythm / Q000187:drug effects / Q000502:physiology*
chemical_list: D015259:Dopamine Agents; D007980:Levodopa; D004298:Dopamine
keywords: Dopamine; Electroencephalography; Theta oscillations; Working memory