RESULTS The fMRI analysis showed that methylpheni date significantly enhanced activation in bilateral inferior frontal cortex (IFC)/insula during inhibition and time discrimination but had no effect on working memory networks .
The meta- analysis , including 14 fMRI data sets and 212 children with ADHD , showed that stimulants most consistently enhanced right IFC/insula activation , which also remained for a subgroup analysis of methylpheni date effects alone .
A more lenient threshold also revealed increased putamen activation .
CONCLUSIONS Psychostimulants most consistently increase right IFC/insula activation , which are key areas of cognitive control and also the most replicated neurocognitive dysfunction in ADHD .
These neurocognitive effects may underlie their positive clinical effects
BACKGROUND Psychostimulant medication , most commonly the catecholamine agonist methylpheni date , is the most effective treatment for attention-deficit/hyperactivity disorder ( ADHD ) .
However , relatively little is known on the mechanisms of action .
Acute effects on brain function can eluci date underlying neurocognitive effects .
We tested methylpheni date effects relative to placebo in functional magnetic resonance imaging ( fMRI ) during three disorder-relevant tasks in medication-naïve ADHD adolescents .
In addition , we conducted a systematic review and meta- analysis of the fMRI findings of acute stimulant effects on ADHD brain function .
Methylphenidate normalises activation and functional connectivity deficits in attention and motivation networks in medication-naïve children with ADHD during a rewarded continuous performance task
BACKGROUND Children with Attention Deficit Hyperactivity Disorder ( ADHD ) have deficits in motivation and attention that can be ameliorated with the indirect dopamine agonist Methylpheni date ( MPH ) . We used functional magnetic resonance imaging ( fMRI ) to investigate the effects of MPH in medication-naïve children with ADHD on the activation and functional connectivity of " cool " attentional as well as " hot " motivation networks . METHODS 13 medication-naïve children with ADHD were scanned twice , under either an acute clinical dose of MPH or Placebo , in a r and omised , double-blind design , while they performed a rewarded continuous performance task that measured vigilant selective attention and the effects of reward . Brain activation and functional connectivity was compared to that of 13 healthy age-matched controls to test for normalisation effects of MPH . RESULTS MPH normalised performance deficits that were observed in children with ADHD compared to controls . Under placebo , children with ADHD showed reduced activation and functional inter-connectivity in bilateral fronto-striato-parieto-cerebellar networks during the attention condition , but enhanced activation in the orbitofrontal and superior temporal cortices for reward . MPH within children with ADHD enhanced the activation of fronto-striato-cerebellar and parieto-temporal regions . Compared to controls , MPH normalised differences during vigilant attention in parieto-temporal activation and fronto-striatal and fronto-cerebellar connectivity ;  MPH also normalised the enhanced orbitofrontal activation in children with ADHD in response to reward . CONCLUSIONS MPH normalised attention differences between children with ADHD and controls by both up-regulation of dysfunctional fronto-striato-thalamo-cerebellar and parieto-temporal attention networks and down-regulation of hyper-sensitive orbitofrontal activation for reward processing . MPH thus shows context -dependent dissociative modulation of both motivational and attentional neuro-functional networks in children with ADHD
RESULTS The fMRI analysis showed that methylpheni date significantly enhanced activation in bilateral inferior frontal cortex (IFC)/insula during inhibition and time discrimination but had no effect on working memory networks .
The meta- analysis , including 14 fMRI data sets and 212 children with ADHD , showed that stimulants most consistently enhanced right IFC/insula activation , which also remained for a subgroup analysis of methylpheni date effects alone .
A more lenient threshold also revealed increased putamen activation .
CONCLUSIONS Psychostimulants most consistently increase right IFC/insula activation , which are key areas of cognitive control and also the most replicated neurocognitive dysfunction in ADHD .
These neurocognitive effects may underlie their positive clinical effects
BACKGROUND Psychostimulant medication , most commonly the catecholamine agonist methylpheni date , is the most effective treatment for attention-deficit/hyperactivity disorder ( ADHD ) .
However , relatively little is known on the mechanisms of action .
Acute effects on brain function can eluci date underlying neurocognitive effects .
We tested methylpheni date effects relative to placebo in functional magnetic resonance imaging ( fMRI ) during three disorder-relevant tasks in medication-naïve ADHD adolescents .
In addition , we conducted a systematic review and meta- analysis of the fMRI findings of acute stimulant effects on ADHD brain function .