INFORMATION-PROCESSING IN CHILDREN WITH MINOR NEUROLOGICAL DYSFUNCTION - BEHAVIORAL AND NEUROPHYSIOLOGICAL INDEXES

Minor neurological dysfunction (MND) refers to deviant function of the central nervous system in the absence of localizable neurological dis orders. Children with no signs (n = 28) and with varying grades of MND (n = 48), classified according to failure on circumscript neurologica l subsystems, were administered selective and sustained attention task s at the age of twelve. During the execution of one of the tasks, elec trocortical activity of the brain was recorded at the Fz, Cz, Pz and O z scalp locations. Of main interest were behavioural and electrophysio logical indices of deficits in attentional control. With respect to th e latter category, the investigation was focused on differences in eve nt-related potential amplitudes reflecting subprocesses of cognitive p rocessing (processing negativity, P300). Following a linear stage mode l of information processing, it was found that children who failed on three or more neurological subsystems (in particular on fine manipulat ion and coordination), exhibited deficits in the encoding, search and decision stages of processing. Furthermore, the children with MND show ed a reduced positive parietal shift on target presentation. Under com plex task conditions, children without MND showed a decrease in P300 a mplitude which reflects the impact of processing negativity as a resul t of increased task demands; this effect was absent in children with M ND. These electrocortical differences suggest imbalances in the extern al and internal neural regulation of the flow of information in the br ain.