Electrophysiological evaluation of human brain development.

The complex development of the human brain during infancy can only be understood by convergent structural, functional, and behavioral measurements. The evaluation of event-related potentials (ERPs) is the most effective current way to look at infant brain function. ERP paradigms can be used to examine the simple transmission of sensory information to the cortex and the discrimination of this information within the cortex. The main developmental changes involve localization of function as the brain becomes tuned to the experienced world (related to synaptic pruning) and a speeding up of transmission as pathways become efficient (related to myelination). ERPs that occur in relation to different temporal aspects of a stimulus (onset-responses, offset-responses, sustained potentials and steady-state responses) and ERPs recorded at different stimulus rates may help track perceptual development from a temporal perspective. Particularly important in human development are the ERP changes that occur in the processing of speech sounds and human faces. At present, ERP studies can show differences between groups of subjects that can demonstrate developmental disorders or elucidate mechanisms of development. However, because of their variability, ERPs are less helpful in determining whether an individual infant is developing abnormally. Where possible, ERP measurements should be used in conjunction with behavioral tests so as to relate performance to mechanism, and with anatomical brain measurements to relate mechanism to structure.