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Neuroimage. 2014 Jul 1;94:185-192. doi: 10.1016/j.neuroimage.2014.03.011. Epub 2014 Mar 15.

Dopaminergic stimulation facilitates working memory and differentially affects prefrontal low theta oscillations.

Author information

1
Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
2
Cognition and Brain Plasticity Group, University of Barcelona, Bellvitge Hospital, C/Feixa Llarga S/N, 08907 L'Hospitalet de Llobregat, Spain.
3
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.

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.

KEYWORDS:

Dopamine; Electroencephalography; Theta oscillations; Working memory

[Indexed for MEDLINE]

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