Understanding the neurobiology of life experience. Research should examine and specify the ways that life experiences, operating intensively or over long segments of the life cycle, produce lasting changes in the nervous system. An illustration of this research approach is the recent development of a model for research on the biological effects of the experience of racism (Clark et al., 1999). The model offers plausible links from experienced racism to psychological stress to biological manifestations in the endocrine and cardiovascular systems that may in turn be associated with cognitive functioning. Developments more broadly in psychoneuroimmunology (Ader and Cohen, 1993; Maier et al., 1994) and related fields that link life experiences to health outcomes (e.g., Karasek and Theorell, 1990; Rushing et al., 1992; Schnall et al., 1994; Seeman, 1996; Wang and Mason, 1999) are improving the capability to conduct research on the ways in which behavioral variables affect the complex biological systems that support cognition. Research on the neural effects of training and practice may also suggest causal mechanisms that link life experiences to specific neural changes. Such progress in linking experiential to physiological variables is bringing the field of neurobiology of life experience to the edge of development.
Research in this emerging field should focus on identifying specific kinds and durations of experience that alter the brain in ways that affect the course of cognitive aging and on identifying the mechanisms by which these effects occur. Research under this initiative could include studies of the neural consequences of professional expertise; cognitive training and practice; emotional and motivational activity; education and sociocultural involvement; retirement; changes in family structure; social interactions and social support; experiences associated with social class, race, and ethnic group membership; spirituality; and other experiential factors that may affect cognitive functioning through effects on neural processes. It could also include studies that examine the neural effects of adaptations to the above kinds of experience. Additional studies could test experiential interventions (e.g., types of training) that might affect the brain in ways that help protect against cognitive decline. The studies would include both attempts to establish causal relationships and to develop process models that further clarify chains of causation. They would also aim to specify life experiences that alter the brain, particularly those that protect against cognitive decline and that could be used to prolong the ability of older people to perform cognitive tasks.
It is worth emphasizing that research on the neurobiology of experience turns on its head the usual understanding of how biology relates to behavior. Rather than reducing social categories to neural phenomena, it would attempt to understand how individual and social experiences shape the brain. Progress in this research direction requires new collaborations between social scientists and neuroscientists that focus on a neglected aspect of biology-culture interactions. We believe social scientists will be attracted to studying