We neuropsychologically assessed cognitive deficits in 109 children with symptoms of attention-deficit/hyperactivity disorder (ADHD) and 51 children with typical development aged 7-8 years and 9-10 years and visually analyzed resting-state electroencephalography (EEG). The EEG recordings of children with ADHD more frequently contained EEG patterns of frontothalamic non-optimal functioning compared with controls, reflected by groups of bilaterally synchronous frontal theta waves (FTWs) and right hemisphere local deviations of brain electrical activity. We found cognitive impairments associated with ADHD in children with different deviations of resting-state EEG. Children with FTWs in both age groups exhibited pronounced difficulties in programming, regulation and control (executive functions), and verbal performance. Children with right hemisphere local EEG abnormalities had executive dysfunction combined with difficulties in nonverbal performance. Executive performance in typically developing children significantly improved from 7-8 to 9-10 years of age. An analysis of neuropsychological scores in children with ADHD symptoms from age 7-8 to 9-10 with the same EEG abnormalities indicated specific age-related improvement of cognitive abilities. In children whose EEG showed patterns of fronto-thalamic involvement presented significant improvement in executive and verbal performance from 7-8 to 9-10 years of age. Overcoming the same age gap in children with right hemisphere local EEG deviations significantly improved only nonverbal performance, whereas improvements in executive function were not statistically significant.

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Executive functions involved in adaptive behavior are among the main subjects of studies on human intellectual activity.This aspect of human psychology first attracted the attention of researchers when the role of the frontal lobes of the brain in the organization of purposive behavior was discovered. Until a certain moment, the frontal cortical regions had been considered "silent areas" because damage to these regions caused neither paralyses nor sensory disorders. As Luriya [1] noted, this notion was revised owing to studies by V.M. Bechterev, L. Bianchi, H. Jackson, I.P. Pavlov, and others who demonstrated that damage to the frontal cerebral regions makes behavior nonpurposive and maladaptive and impairs the assessment of external impressions, coordination between sensory and motor activities, synthesis of purpose-oriented movements, etc.Luriya studied the effects of damage to the frontal lobes and used the original data, as well as the results of other experimental studies and clinical observations, to analyze the executive functions involved in purposive activity [1][2][3]. Afterwards, Luriya united these functions into cerebral block III (the block of executive functions), assuming that the anterior regions of the cerebral hemispheres (mainly, the frontal lobes) are the main cerebral substrate of the executive functions [4,5]. Luriya defined block III as an apparatus programming the movements and activities, controlling current processes, and comparing the effects of activities with initial intentions [4]. In addition, Luriya distinguished the block of tone and wakefulness control (block I) and the block of information perception, processing, and storage (block II). Like the other two blocks, block III plays a specific role in mental activity and behavior control, which is necessary for all types of mental activity [5].Luriya, a Russian researcher, is believed to be among the authors of the term executive functions [6]. In the Russian literature, however, executive functions are also referred to as functions of activity programming, regulation, and control (a literal translation). * Different researchers suggest, in general, similar definitions of executive functions. Anderson [7] notes that executive functions are necessary for goal formation and purposive activity. Lezak [8] believes that these functions allow a person to perform successfully independent, purpose-related, self-supported (self-regulated) behavior. Stuss [9] suggested an integrative model of executive functions comprising a set of abilities that allow an individual to form goals, retain them in active memory, trace their attainment, and control the encountered obstacles. Welsh et al.[10] interpreted executive functions as those facilitating future-oriented behavior by planning, using flexible strategies, impulse control, and organized search.Thus, all authors consider executive functions to account for planning, regulation, and control of purposive behavior.To understand executive functions, it is important to determine their components.Mo...