Motor overflow in children with attention-deficit/hyperactivity disorder is associated with decreased extent of neural activation in the motor cortex.
Motor overflow is a developmental phenomenon that typically disappears by late childhood. Abnormal persistence of motor overflow is often present in children with attention-deficit/hyperactivity disorder (ADHD). This study employed functional magnetic resonance imaging (fMRI) during a finger-sequencing task to examine whether excessive motor overflow in children with ADHD is associated with decreased extent of motor circuit activation. Thirty-four right-handed children (18 typically developing controls, 16 ADHD) completed fMRI while performing a finger-sequencing task. Motor overflow was evaluated during a finger-sequencing task and a motor examination (the PANESS) performed outside the scanner. Diagnostic differences in behavioral measures of overflow and extent of activation in the contralateral and ipsilateral motor network ROIs were examined, along with correlations between overflow and extent of activation. Children with ADHD demonstrated greater overflow and lesser extent of activation in left primary motor cortex (BA4) and bilateral premotor cortex (BA6) and supplementary motor area (SMA) during right-hand finger-sequencing compared to controls. Decreased extent of primary motor and premotor activation correlated with increased hand-related overflow movements in children with ADHD but not controls. These findings suggest that overflow movements in children with ADHD may reflect decreased recruitment of neural circuitry involved in active inhibition of homologous motor circuitry unnecessary to task execution.
Center for Neurodevelopmental and Imaging Research, Kennedy Krieger Institute, Baltimore, MD, USA.
Andrew
A
Gaddis
Center for Neurodevelopmental and Imaging Research, Kennedy Krieger Institute, Baltimore, MD, USA; Department of Neuropsychology, Kennedy Krieger Institute, Baltimore, MD, USA; Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, School of Medicine, Baltimore, MD, USA. Electronic address: rosch@kennedykrieger.org.
Keri S
KS
Rosch
Center for Neurodevelopmental and Imaging Research, Kennedy Krieger Institute, Baltimore, MD, USA.
Benjamin
B
Dirlikov
Center for Neurodevelopmental and Imaging Research, Kennedy Krieger Institute, Baltimore, MD, USA.
Deana
D
Crocetti
Center for Neurodevelopmental and Imaging Research, Kennedy Krieger Institute, Baltimore, MD, USA.
Lindsey
L
MacNeil
Center for Neurodevelopmental and Imaging Research, Kennedy Krieger Institute, Baltimore, MD, USA.
Anita D
AD
Barber
Center for Neurodevelopmental and Imaging Research, Kennedy Krieger Institute, Baltimore, MD, USA; Department of Biostatistics, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
John
J
Muschelli
Department of Biostatistics, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
Brian
B
Caffo
The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
James J
JJ
Pekar
Center for Neurodevelopmental and Imaging Research, Kennedy Krieger Institute, Baltimore, MD, USA; Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, School of Medicine, Baltimore, MD, USA; The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Stewart H
SH
Mostofsky
D001288:Attention / Q000502:physiology; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis* / Q000378:metabolism*; D002648:Child; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007266:Inhibition, Psychological; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009044:Motor Cortex / Q000378:metabolism*; D009068:Movement / Q000502:physiology; D009415:Nerve Net / Q000378:metabolism*; D010775:Photic Stimulation / Q000379:methods; D017397:Prefrontal Cortex / Q000378:metabolism
Finger-sequencing; Inhibition; PANESS; fMRI