Dopamine modulates processing speed in the human mesolimbic system

Eckart, Cindy; Bunzeck, Nico

doi:10.1016/j.neuroimage.2012.11.001

Cited by 35 publications

(35 citation statements)

References 52 publications

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“…We have recently shown that-in the absence of reward-neural novelty signals are accelerated to o100 ms following levodopa administration (Eckart and Bunzeck, 2013). Under the assumption that reward prospect leads to dopamine release (Schott et al, 2008;Schultz et al, 1997;Tobler et al, 2005), these and our current results suggest that there is no linear but an inverted u-shaped relationship between dopamine levels and the temporal dynamics of novelty processing (Figure 4).…”

Section: Discussionsupporting

confidence: 61%

“…Under the assumption that reward prospect leads to dopamine release (Schott et al, 2008;Schultz et al, 1997;Tobler et al, 2005), these and our current results suggest that there is no linear but an inverted u-shaped relationship between dopamine levels and the temporal dynamics of novelty processing (Figure 4). That means, with 'normal' dopamine levels (ie, in the absence of reward or pharmacological manipulations), old/new responses typically emerge at B200 ms after stimulus onset (Rugg and Curran, 2007); if dopamine levels are slightly enhanced to an 'optimum', either by pharmacological means (Eckart and Bunzeck, 2013) or in the context of reward motivation (Bunzeck et al, 2009), these old/new responses peak at B100 ms. If, on the other hand, dopamine levels exceed the optimal range-as in our study, that is, in the context of reward together with levodopa administration-the onset of old/new responses is even slower than 'normal' and thus emerges not earlier than B400 ms after stimulus presentation.…”

Section: Discussionmentioning

confidence: 99%

“…Levodopa is licensed for the treatment of Parkinson's disease and provokes only little to no side effects if taken in low dosages. It has been used in previous imaging studies (eg, Guitart-Masip et al, 2012;Bunzeck et al, 2013;Eckart and Bunzeck, 2013).…”

Section: Participantsmentioning

confidence: 99%

“…These findings show that the chronometry of neural novelty processing (ie, differences in event-related responses to old vs new items) can be modulated by reward motivation, and they suggest that such acceleration might be due to a functional interaction between novelty and reward, which is based on common neural substrates in the dopaminergic mesolimbic system. Support for this notion comes from a recent study using magnetoencephalography (MEG) together with a non-rewarded memory task (Eckart and Bunzeck, 2013). It revealed that stimulating the dopaminergic system through levodopa leads to faster novelty responses during the incidental encoding of repeatedly presented scene images.…”

Section: Introductionmentioning

confidence: 99%

“…In the placebo group, we expected reward-driven early old/new effects (peaking at B100 ms) over temporal/occipital sensors (Bunzeck et al, 2009) that would be modulated by levodopa. One hypothesis was that stimulating the dopaminergic system leads to further acceleration indicating a monotonic relationship between dopamine levels and the onset of neural novelty responses (Eckart and Bunzeck, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Dopamine Controls the Neural Dynamics of Memory Signals and Retrieval Accuracy

Apitz

Bunzeck

2013

Neuropsychopharmacol

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The human brain is capable of differentiating between new and already stored information rapidly to allow optimal behavior and decision-making. Although the neural mechanisms of novelty discrimination were often described as temporally constant (ie, with specific latencies), recent electrophysiological studies have demonstrated that the onset of neural novelty signals (ie, differences in event-related responses to new and old items) can be accelerated by reward motivation. While the precise physiological mechanisms underlying this acceleration remain unclear, the involvement of the neurotransmitter dopamine in both novelty and reward processing suggests that enhanced dopamine levels in the context of reward prospect may have a role. To investigate this hypothesis, we used magnetoencephalography (MEG) in combination with an old/new recognition memory task in which correct discrimination between old and new items was rewarded. Importantly, before the task, human subjects received either 150 mg of the dopamine precursor levodopa or placebo. For the placebo group, old/new signals peaked at B100 ms after stimulus onset over left temporal/occipital sensors. In contrast, after levodopa administration earliest old/new effects only emerged after B400 ms and retrieval accuracy was reduced as expressed in lower d 0 values. As such, our results point towards a previously unreported role of dopamine in controlling the chronometry of neural processes underlying the distinction between old and new information. They also suggest that this relationship follows a nonlinear function whereby slightly enhanced dopamine levels accelerate neural/cognitive processes and excessive dopamine levels impair them.

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Section: Discussionsupporting

confidence: 61%

Section: Discussionmentioning

confidence: 99%

Section: Participantsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dopamine Controls the Neural Dynamics of Memory Signals and Retrieval Accuracy

Apitz

Bunzeck

2013

Neuropsychopharmacol

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Individual differences in EEG correlates of recognition memory due to DAT polymorphisms

et al. 2017

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IntroductionAlthough previous research suggests that genetic variation in dopaminergic genes may affect recognition memory, the role dopamine transporter expression may have on the behavioral and EEG correlates of recognition memory has not been well established.ObjectivesThe study aims to reveal how individual differences in dopaminergic functioning due to genetic variations in the dopamine transporter gene influences behavioral and EEG correlates of recognition memory.MethodsFifty‐eight participants performed an item recognition task. Participants were asked to retrieve 200 previously presented words while brain activity was recorded with EEG. Regions of interest were established in scalp locations associated with recognition memory. Mean ERP amplitudes and event‐related spectral perturbations when correctly remembering old items (hits) and recognizing new items (correct rejections) were compared as a function of dopamine transporter group.ResultsParticipants in the dopamine transporter group that codes for increased dopamine transporter expression (10/10 homozygotes) display slower reaction times compared to participants in the dopamine transporter group associated with the expression of fewer dopamine transporters (9R‐carriers). 10/10 homozygotes further displayed differences in ERP and oscillatory activity compared to 9R‐carriers. 10/10 homozygotes fail to display the left parietal old/new effect, an ERP signature of recognition memory associated with the amount of information retrieved. 10/10 homozygotes also displayed greater decreases of alpha and beta oscillatory activity during item memory retrieval compared to 9R‐carriers.ConclusionCompared to 9R‐carriers, 10/10 homozygotes display slower hit and correct rejection reaction times, an absence of the left parietal old/new effect, and greater decreases in alpha and beta oscillatory activity during recognition memory. These results suggest that dopamine transporter polymorphisms influence recognition memory.

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Striatal and midbrain connectivity with the hippocampus selectively boosts memory for contextual novelty

Kafkas

Montaldi

2015

Hippocampus

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The role of contextual expectation in processing familiar and novel stimuli was investigated in a series of experiments combining eye tracking, functional magnetic resonance imaging, and behavioral methods. An experimental paradigm emphasizing either familiarity or novelty detection at retrieval was used. The detection of unexpected familiar and novel stimuli, which were characterized by lower probability, engaged activity in midbrain and striatal structures. Specifically, detecting unexpected novel stimuli, relative to expected novel stimuli, produced greater activity in the substantia nigra/ventral tegmental area (SN/VTA), whereas the detection of unexpected familiar, relative to expected, familiar stimuli, elicited activity in the striatum/globus pallidus (GP). An effective connectivity analysis showed greater functional coupling between these two seed areas (GP and SN/VTA) and the hippocampus, for unexpected than for expected stimuli. Within this network of midbrain/striatal–hippocampal interactions two pathways are apparent; the direct SN–hippocampal pathway sensitive to unexpected novelty and the perirhinal–GP–hippocampal pathway sensitive to unexpected familiarity. In addition, increased eye fixations and pupil dilations also accompanied the detection of unexpected relative to expected familiar and novel stimuli, reflecting autonomic activity triggered by the functioning of these two pathways. Finally, subsequent memory for unexpected, relative to expected, familiar, and novel stimuli was characterized by enhanced recollection, but not familiarity, accuracy. Taken together, these findings suggest that a hippocampal–midbrain network, characterized by two distinct pathways, mediates encoding facilitation and most critically, that this facilitation is driven by contextual novelty, rather than by the absolute novelty of a stimulus. This contextually sensitive neural mechanism appears to elicit increased exploratory behavior, leading subsequently to greater recollection of the unexpected stimulus. © 2015 The Authors Hippocampus Published by Wiley Periodicals, Inc.

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Dopamine modulates processing speed in the human mesolimbic system

Cited by 35 publications

References 52 publications

Dopamine Controls the Neural Dynamics of Memory Signals and Retrieval Accuracy

Dopamine Controls the Neural Dynamics of Memory Signals and Retrieval Accuracy

Individual differences in EEG correlates of recognition memory due to DAT polymorphisms

Striatal and midbrain connectivity with the hippocampus selectively boosts memory for contextual novelty

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