Functional magnetic resonance imaging evidence for abnormalities in response selection in attention deficit hyperactivity disorder: differences in activation associated with response inhibition but not habitual motor response.

Mark McIntosh,'s picture
PubMed URL: 
http://www.ncbi.nlm.nih.gov/pubmed/18004945
Author: 
Mostofsky SH
Author List: 
Suskauer SJ
Simmonds DJ
Fotedar S
Blankner JG
Pekar JJ
Denckla MB
Mostofsky SH
Journal: 
J Cogn Neurosci
PubMed ID: 
18004945
Pagination: 
478-93
Volume: 
20
Issue: 
3
Abstract: 
Impaired response inhibition is thought to be a core deficit in attention deficit hyperactivity disorder (ADHD). Prior imaging studies investigating response inhibition in children with ADHD have used tasks involving different cognitive resources, thereby complicating the interpretation of their findings. In this study, a classical go/no-go task with a well-ingrained stimulus-response association (green = go; red = no-go) was used in order to minimize extraneous cognitive demands. Twenty-five children with ADHD and 25 typically developing (TD) children between the ages of 8 and 13 years and group-matched for IQ and performance on the go/no-go task were studied using event-related functional magnetic resonance imaging (fMRI). Analyses were used to examine differences in activation between the ADHD and TD groups for "go" (habitual motor response) and "no-go" (requiring inhibition of the motor response) events. Region-of-interest analyses revealed no between-group difference in activation in association with "go" events. For "no-go" events, the children with ADHD demonstrated significantly less activation than did TD controls within a network important for inhibiting a motor response to a visual stimulus, with frontal differences localized to the pre-supplementary motor area. Although blood oxygenation level-dependent fMRI data show no differences between children with ADHD and TD children in association with a habituated motor "go" response, during "no-go" events, which require selecting not to respond, children with ADHD show diminished recruitment of networks important for response inhibition. The findings suggest that abnormalities in circuits important for motor response selection contribute to deficits in response inhibition in children with ADHD and lend support to the growing awareness of ADHD-associated anomalies in medial frontal regions important for the control of voluntary actions.
Published Date: 
March, 2008

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