Dopaminergic modulation of response inhibition: an fMRI study

Abstract

Dopamine has been hypothesized to modulate response inhibition. To test this hypothesis, we used functional magnetic resonance imaging (fMRI) to measure the effects of the dopamine prodrug levodopa on the brain responses to a well-validated response inhibition task (go/no-go, or GNG). Since abnormalities of response inhibition and dopamine have been thought to underlie tics and other symptoms of Tourette syndrome, we studied 8 neuroleptic-naive adults with tic disorders as well as 10 well-matched healthy controls. Subjects were pretreated with the peripheral decarboxylase inhibitor carbidopa, then scanned during GNG and control blocks, both before and during i.v. levodopa infusion. Both groups had similar task performance and task-related regional brain activity before and during levodopa infusion. Levodopa did not affect reaction times or accuracy, so fMRI findings can be interpreted without concern that they simply reflect a performance difference between conditions. Levodopa did affect the magnitude of GNG-related fMRI responses in the right cerebellum and right parietal cortex, significantly reducing both. Pre-levodopa activity in the right cerebellum correlated with reaction times (higher magnitudes associated with faster reaction times), and pre-levodopa activity in the right parietal cortex correlated with false alarm rate (higher magnitudes associated with higher error). In summary, right parietal and cerebellar regions important in mediating specific aspects of the GNG task were modulated by levodopa, suggesting a region-specific role for dopamine in response inhibition. D 2004 Elsevier B.V. All rights reserved.Theme: Neural basis of behavior Topic: Cognition

The utility of rat models of impulsivity in developing pharmacotherapies for impulse control disorders

“…However, opposite effects of this drug and amphetamine are observed on the SST (Bari et al ., 2009; Loos et al ., 2010). Furthermore, administration of the DA precursor L‐DOPA increases impulsive choice (Pine et al ., 2010) in human volunteers, but does not affect SST or go/no‐go performance (Overtoom et al ., 2003; Hershey et al ., 2004). Acute administration of pramipexole also does not affect go/no‐go or delay‐discounting performance in healthy control subjects (Hamidovic et al ., 2008).…”

Abnormal thalamic volume in treatment‐naïve boys with Tourette syndrome

“…For example, neurosurgical interventions on the thalamus decreased TS symptoms in treatment‐refractory TS patients (2–5). Functional neuroimaging study on adult TS patients also showed metabolic abnormalities of the thalamus (6–8).…”

Increased picture–word interference in chronic and recreational users of cocaine

“…The frontostriatal circuitry has been suggested as the neural basis of inhibition (Bari & Robbins, ; Miller & Cohen, ). Dopamine is the main chemical messenger targeted by cocaine (Hershey et al, ); it plays a crucial modulatory role (Arnsten, Wang, & Paspalas, ; Robbins & Arnsten, ). Earlier studies of inhibitory control in cocaine users have shown diminished prefrontal activity compared with healthy controls when performing tasks tapping conflict resolution and inhibitory control (e.g., Go–No go, Stop–Signal, and Stroop; for a review, see Goldstein & Volkow, ).…”