ADHD Research Today is a free monthly online journal that collates and summarizes the latest research about ADHD, including details on attention-deficit hyperactivity disorder, drugs, treatment, symptoms. | ||||||||
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The ipsilateral silent period in boys with attention-deficit/hyperactivity disorder.Garvey MA, Barker CA, Bartko JJ, Denckla MB, Wassermann EM, Castellanos FX, Dell ML, Ziemann U Pediatric Movement Disorders Unit, Human Motor Control Section, MNB, NINDS, National Institutes of Health, Bethesda, MD 20892, USA. marjorie.garvey@medstar.net OBJECTIVE: Characterize maturation of transcallosal inhibition (ipsilateral silent period [iSP]) in attention deficit/hyperactivity disorder (ADHD) using transcranial magnetic stimulation (TMS). BACKGROUND: Maturation of the iSP is related to acquisition of fine motor skills in typically developing children suggesting that dexterous fine motor skills depend upon mature interhemispheric interactions. Since neuromotor maturation is abnormal in boys with ADHD we hypothesized that iSP maturation in these children would be abnormal. We studied iSP maturation in 12 boys with ADHD and 12 age-matched, typically developing boys, 7-13 years of age. METHODS: Surface electromyographic activity was recorded from right first dorsal interosseus (FDI). During background activation, focal TMS was delivered at maximal stimulator output over the ipsilateral motor cortex. RESULTS: Maturation of finger speed in boys with ADHD was significantly slower than that in the control group. The iSP latency decreased with age in the control group but not in the ADHD group. CONCLUSIONS: These findings suggest the presence of a complex relationship between abnormalities of certain interhemispheric interactions (as represented by iSP latency) and delayed maturation of neuromotor skills in boys with ADHD. SIGNIFICANCE: These data provide preliminary physiologic evidence supporting delayed or abnormal development of interhemispheric interactions in boys with ADHD. Published 29 July 2005 in Clin Neurophysiol, 116(8): 1889-96.
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