[Recent contributions from magnetoencephalography to the neurobiology of attention-deficit/hyperactivity disorder]

Current theories postulate that the core cognitive deficit in attention-deficit/hyperactivity disorder (ADHD) is an executive dysfunction. Neuroimaging studies on the whole have provided both anatomical and functional evidence supporting the fronto-striatal dysfunction hypothesis in ADHD. However, recent neuroimaging studies have found anatomical and functional impairments in posterior cortical regions, such as the inferior parietal and posterior temporal cortices, which have been related to a deficit in selective attention. Event related potential (ERP) studies show that ADHD children have an impairment in early components (within the first 200 ms of processing), such as P1 or N1, both of which are sensitive to selective attention effects. These findings cast doubt regarding the fronto-striatal/executive dysfunction as the core deficit in ADHD.

One of the main objectives of ADHD research is the search for its core cognitive deficit and the neural networks underlying it, because it has important repercussions over ADHD diagnosis and treatment. High temporal resolution techniques, such as ERP or magnetoencephalography may be particularly useful in distinguishing the precise moment of cognitive processing during which the brain activity of children with ADHD begins to be impaired. As a consequence, this may help to elucidate the core cognitive deficit in ADHD.