The importance of regressive changes in the development of the nervous system: towards a neurobiological theory of child development.

In this paper we propose that theories of early personality development be revised to consider knowledge of neurodevelopment. Research findings are reviewed that have established the presence of regressive changes in the normal development of the brain. These regressive changes, consisting of neuronal death and process and synapse elimination, are theoretically linked to three precursors of personality: sex differences, temperamental traits and perceptual-motor coordination. Evidence supporting these hypotheses is provided from studies examining how the effects of genetic, environmental, and experiential factors on brain development may determine the development of these personality features.