An Interdisciplinary Approach to Analysis of the Cerebral Mechanisms of Learning Difficulties in Children. Experience of Studies of Children with Signs of ADHD
We present here an interdisciplinary approach to studies of the cerebral mechanisms of learning difficulties in children of junior school age. A complex electroencephalographic (EEG) and neuropsychological analysis was used to identify neurophysiological factors for cognitive deficits in children aged 7–8 and 9–10 years with signs of attention deficit hyperactivity disorder (ADHD). EEG traces in calm waking in children with signs of ADHD contained patterns characteristic of a nonoptimal state of the frontothalamic regulatory system, with bilaterally synchronous groups of frontal theta waves, along with local deviations in cortical electrical activity in the right hemisphere significantly more commonly than traces from children of the control group. In addition, children with signs of ADHD had a higher frequency of EEG changes pointing to a deficit in the total level of activation by the brainstem reticular formation, in the form of a hypersynchronous alpha rhythm and/or groups of theta waves in the caudal areas, than the control group. Children with signs of ADHD showed a relationship between the characteristics of the cognitive deficit and the presence of one of these three types of EEG abnormality. Children of both age groups with EEG signs of the nonoptimal state of the frontothalamic system demonstrated marked deficiency of programming functions, regulation and control of activity (executive functions), along with difficulties in performing auditory-verbal tasks. In children with local abnormalities of electrical activity in the right hemisphere, the deficit in executive functions was combined with difficulties in performing nonverbal tasks. Decreases in the level of nonspecific activation mainly affected work capacity and the rate of performance of cognitive tasks in both age groups. Children aged 7–8 years with signs of decreased activation also showed difficulty in processing nonverbal information. Thus, the results obtained by interdisciplinary investigations identified at least three types of abnormalities in the functional state of the brain which could produce decreases in the effectiveness of different components of cognitive activity in children with ADHD.