Striatal Dopamine and the Interface between Motivation and Cognition

Brain dopamine has long been known to be implicated in the domains of appetitive motivation and cognition. Recent work indicates that dopamine also plays a role in the interaction between appetitive motivation and cognition. Here we review this work. Animal work has revealed an arrangement of spiraling connections between the midbrain and the striatum that subserves a mechanism by which dopamine can direct information flow from ventromedial to more dorsal regions in the striatum. In line with current knowledge about dopamine's effects on cognition, we hypothesize that these striato-nigro-striatal connections provide the basis for functionally specific effects of appetitive motivation on cognition. One implication of this hypothesis is that appetitive motivation can induce cognitive improvement or impairment depending on task demands

Ventral striatal hyperconnectivity during rewarded interference control in adolescents with ADHD

Objective: Attention-deficit/hyperactivity disorder (ADHD) is characterized by cognitive deficits (e.g., interference control) and altered reward processing. Cognitive control is influenced by incentive motivation and according to current theoretical models, ADHD is associated with abnormal interactions between incentive motivation and cognitive control. However, the neural mechanisms by which reward modulates cognitive control in individuals with ADHD are unknown. Method: We used event-related functional resonance imaging (fMRI) to study neural responses during a rewarded Stroop color-word task in adolescents (14-17 years) with ADHD (n = 25; 19 boys) and healthy controls (n = 33; 22 boys). Results: Adolescents with ADHD showed increased reward signaling within the superior frontal gyrus and ventral striatum (VS) relative to controls. Importantly, functional connectivity analyses revealed a hyperconnectivity between VS and motor control regions in the ADHD group, as a function of reward-cognition integration. Connectivity was associated with performance improvement in controls but not in the ADHD group, suggesting inefficient connectivity. Conclusion: Adolescents with ADHD show increased neural sensitivity to rewards and its interactions with interference control in VS and motor regions, respectively. The findings support theoretical models of altered reward-cognition integration in individuals with ADHD

Group interaction inhibition during gamble pictures.

<p>HCs showed more activation in the bilateral dorsolateral prefrontal cortex, right ventral lateral prefrontal cortex, and right anterior cingulate than PRGs. Results are depicted with a threshold of p<0.001 uncorrected. Colour bar represents corresponding T values.</p

Group interaction negative pictures – neutral pictures.

<p>PRGs showed more activation in the bilateral dorsolateral prefrontal cortex and right dorsal cingulate cortex than HCs. Results are depicted with a threshold of p<0.001 uncorrected to show the extent of the activation. Colour bar represents corresponding T values.</p

Group interaction gamble pictures – neutral pictures.

<p>PRGs showed more activation in the left dorsolateral prefrontal cortex, right ventral striatum, and right anterior cingulate, than HCs. Results are depicted with a threshold of p<0.001 uncorrected to show the extent of activation. Colour bar represents corresponding T values.</p

Group interaction neutral inhibition.

<p>PRGs showed more activation in the bilateral dorsolateral prefrontal cortex cortex, and right anterior cingulate than HCs. Results are depicted at a threshold of p<0.001 uncorrected. Colour bar represents the corresponding T values.</p

Group interaction during positive pictures.

<p>HCs showed more activation in the bilateral dorsolateral prefrontal cortex, and left ventral striatum than PRGs. Results are depicted with a threshold of p<0.001 uncorrected. Colour bar represents corresponding T values.</p

Example of the Go/Nogo Gamble block.

<p>Participants had to respond to gambling related pictures and try to withhold a response to neutral pictures.</p

A: Reaction time during the different Go/NoGo blocks.

<p>HCs = Healthy controls, PRGs = problematic gamblers, msec = milliseconds; ** = significant group difference at p<0.05; * = trend for group differences <i>p</i><0.10; Error bars represent the standard errors of the mean. B: Percentage of impulsive errors during Go/NoGo blocks. HCs = Healthy controls, PRGs = Problematic gamblers, ** = significant group difference at p<0.05; * = trend for group differences <i>p</i><0.10; Error bars represent the standard deviations of the mean.</p

Group interaction positive pictures – neutral pictures.

<p>PRGs showed more activation in the left dorsolateral prefrontal cortex and left inferior frontal gyrus than HCs. Results are depicted with a threshold of p<0.001 uncorrected to show the extent of activation. Colour bar represents corresponding T values.</p