Effects of experience on brain development

influence the developing and mature brain and proposes a new categorization scheme based upon the type of information stored and the brain mechanisms that appear to be involved in storing it. In this scheme, experience-expectant infonnation storage refers to incorporation of environmental in-formation tliat is ubiquitous in the environment and common to all species members, such as the basic elements of pattem perception. Experience-expectant processes appear to have evolved as a neural preparation for incorporating speciBc infonnation: in many sensory systems, synaptic connec-tions between nerve cells are overproduced, and a subsequent selection process occurs in which aspects of sensory experience determine the pattem of connections that remains. Experience-dependent infonnation storage refers to incorporation of environmental information that is idiosyn-cratic, or unique to the individual, such as leaming about one's specific physical environment or vocabulary. The neural basis of experience-dependent processes appears to involve active formation of new synaptic connections in response to tfie events providing the information to be stored. Although these processes probably do not occur entirely independently of one another in develop-ment, the categories oflfer a new view more in accord with neural mechanisms than were terms like "critical " or "sensitive period.&quot