Scalp topography of event-related brain potentials and cognitive transition during childhood.

This study examined the relation between cognitive development and the ontogenesis of event-related brain potentials (ERPs) during childhood. First, the level of cognitive development was assessed in girls between 5 and 7 years of age with a standard Piagetian conservation kit. Then these children performed 2 experimental tasks: a visual selective attention (oddball) task and an experimental analogue of the Piagetian conservation of liquid quantity task. The oddball task required the child to count silently the number of rare stimuli presented in a series of frequent stimuli. The ERPs elicited in this task showed a positive wave with a centroparietal scalp distribution and a maximum amplitude at around 600 ms poststimulus. In the experimental analogue of the conservation of liquid quantity task, the child was presented with a choice stimulus requiring a left- or right-hand button press. The proportion of correct responses discriminated successfully between conservers and nonconservers as established by traditional Piagetian assessment procedures. The ERPs obtained in the experimental analogue of the conservation task were characterized by a broad positivity with a centroparietal scalp distribution. The broad positivity discriminated significantly between nonconservers and conservers but not between age groups. These findings received additional support from topographic and symmetric dipole analyses of the ERPs. The results of the dipole analysis suggested more anterior ERP sources for the nonconservers during the early part of stimulus analysis and more lateralized ERP sources for conservers during the later part of information processing. It is concluded that ERPs may provide a window on the relation between brain maturation and stage-wise cognitive development.