The Interaction Between Sensory and Nonsensory Factors in the Determination of Brain Structure and Chemistry: a Review

Abstract

Contrary to previous thinking, the brain is now recognized as a plastic organ whose structure and function adapt to the functional demands of the sensory environment. This paper examines the interaction between sensory and nonsensory brain-modifying factors in determining the psychobiological outcome in animals reared under conditions of environmental complexity and deprivation. Stimulant drugs appear to enhance complexity effects and depressants to reduce them. Hormones affected by hypophysectomy or castration do not appear to interfere with sensory effects, though a progestogen norethynodrel does appear to interact with them. For genetic effects, strain, species and sex may interact, with male hybrids being perhaps most susceptible to environmental effects. The picture which is emerging is of the brain as inextricably linked to its environment and suggests that a full study demands a recognition of the ecological context. This picture of multiway interdependence and interdetermination or “omnideterminism” is similar to the holistic organismic picture of the universe of the millenia-old yogi-consciousness disciplines and of modern physics.