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Updated: Jan 22, 2026

Intracortical Inhibition Within the Primary Motor Cortex Can Be Modulated by Changing the Focus of Attention
Published on: September 11, 2017
Motor cortex inhibition and modulation in children with ADHD
Donald L Gilbert1, David A Huddleston2, Steve W Wu2
1From the Division of Neurology (D.L.G., D.A.H., S.W.W., E.V.P., P.S.H.) and Department of Psychiatry (E.V.P.), Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, OH; Center for Neurodevelopmental and Imaging Research (K.H., D.C., S.H.M.), Kennedy Krieger Institute, Baltimore; Behavioral Neurology Unit (E.M.W.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda; and Departments of Neurology and Psychiatry (S.H.M.), Johns Hopkins University School of Medicine, Baltimore, MD. Donald.gilbert@cchmc.org.
Children with attention-deficit/hyperactivity disorder (ADHD) exhibit impaired motor cortex inhibition and reduced task-related modulation. These physiological differences correlate with ADHD symptoms and cognitive control deficits.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Developmental Neuroscience
Background:
- Children with ADHD show impaired motor cortex physiology, specifically reduced short-interval cortical inhibition (SICI), compared to typically developing peers.
- Perturbed motor cortex (M1) physiology in ADHD may be linked to behavioral dysfunction in cognitive control tasks.
Purpose of the Study:
- To investigate if M1 physiology abnormalities in children with ADHD are associated with behavioral deficits during a cognitive control task.
- To evaluate M1 physiology during rest and a response inhibition task in children with and without ADHD.
Main Methods:
- A case-control study involving 131 children (66 ADHD, 65 TD) aged 8-12 years.
- Transcranial magnetic stimulation (TMS) assessed M1 physiology (MEP amplitudes, SICI) at rest and during a modified stop-signal reaction task.
- Behavioral ratings and motor skills were also evaluated.
Main Results:
- Children with ADHD exhibited slower and more variable go responses.
- ADHD group showed reduced M1 SICI at rest and during task performance.
- Task-related up-modulation (TRUM) of M1 excitability during inhibition was less robust in ADHD, correlating with symptom severity and slower reaction times.
Conclusions:
- Children with ADHD demonstrate anomalous M1 physiology, including deficient SICI and reduced TRUM.
- These physiological findings are associated with ADHD symptoms and impaired cognitive control, suggesting underlying biological mechanisms warrant further investigation.
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