Experience and Brain Development

Abstract

This article considers how experience can 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 information storage refers to incorporation of environmental information that is ubiquitous in the environment and common to all species members, such as the basic elements of pattern perception. Experience-expectant processes appear to have evolved as a neural preparation for incorporating specific information: in many sensory systems, synaptic connections between nerve cells are overproduced, and a subsequent selection process occurs in which aspects of sensory experience determine the pattern of connections that remains. Experience-dependent information storage refers to incorporation of environmental information that is idiosyncratic, or unique to the individual, such as learning 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 the events providing the information to be stored. Although these processes probably do not occur entirely independently of one another in development, the categories offer a new view more in accord with neural mechanisms than were terms like "critical" or "sensitive period."

Brain and cognitive evolution: Forms of modularity and functions of mind.

“…Experience-based change in brain functioning and topographic organization has also been demonstrated in normally developing brains, beginning with the seminal studies of Rosenzweig and colleagues (e.g., Rosenzweig & Bennett, 1972;Rosenzweig, Krech, Bennett, & Diamond, 1962;Rosenzweig, Krech, Bennett, & Zolman, 1962) and Greenough and colleagues (see Greenough et al, 1987). In the former studies, newly weaned rats were exposed to varying degrees of social and environmental enrichment or impoverishment.…”

“…The mechanisms underlying the interaction between experience-independent architecture and experience-dependent modifications are not fully understood. One view is that overgeneration of synaptic connections in the neocortex of some mammals results in an increased sensitivity to early experiences (Huttenlocher, 1990) and that actual experience patterns result in the selective maintenance (active connections) or degeneration (inactive connections) of synaptic connections (Greenough et al, 1987). Some recent work suggests that the mechanism may be more complex, whereby experiential patterns dynamically influence the organization of cortical fields rather than simply maintaining preorganized fields (White et al, 2001).…”

“…One end is represented by the position that brain and mind are a constellation of modular systems with a high degree of inherent constraint (Fodor, 1983;Lenneberg, 1967;Pinker, 1994;Tooby & Cosmides, 1995), although the expression of different features of these systems can be contingent on early experiences (Greenough, Black, & Wallace, 1987). As an example, the brain and cognitive systems involved in processing phonemes (e.g., ba, da) are conceptualized as inherent, but the phenotypic expression of one phonemic system or another is contingent on early exposure to associated sounds (Cosmides & Tooby, 1994).…”

Developmental cognitive neuroscience: progress and potential

“…However, it became evident that such hard-and-fast distinctions are too simplistic, and this is acknowledged in later terminology (such as experience-expectant and experience-dependent processes, which incorporate genetic and environmental factors): Experience-expectant processes [33]: processes that utilize environmental information that is highly reliable for all members of the species (e.g. for humans, hearing a language) Experience-dependent processes [33]: processes that utilize environmental information that can vary across individuals (e.g. for humans, the particular language that is heard) Sensitive periods: time-limited windows when specific experiences have their largest effects.…”

“…[31,32]). Learning plays a key role in an activity-mediated competition process through which some of these synapses are eliminated or pruned, and others are stabilized and strengthened [1,33,34].…”