Researchers from the University of California Davis have been analyzing brain activity in children with ADHD (Attention Deficit Hyperactivity Disorder). The children were led to expect either a visual or auditory signal and their brain activity was monitored. In unaffected children signals are sent from the frontal cortex to the parts of the brain that deal with visual or auditory stimuli to prepare them for action, as it were. These signals led to a drop in alpha waves (the brain's 'screensavers') in the appropriate region. However, in the children with ADHD there was no drop in alpha waves indicating a disconnection between the part of the brain that allocates attention and the parts attention is being allocated to.