Environmental influences on the neocortex in later life.

Publisher Summary This chapter discusses the environmental influences on the neocortex in later life. The focus is on the effects of differential environmental experience on dendrites of cortical pyramidal cells in adult rats. The conditions commonly used in the differential environmental experience paradigm are—(1) the enriched condition (EC), in which 12 rats of the same sex are housed in a large cage, exposed daily to a new set of 6 or more toys, and placed for about a half hour each day in a Hebb-Williams maze apparatus; (2) the social or standard condition (SC), in which three rats of the same sex are housed in a standard laboratory cage without any toys or exploration of the Hebb-Williams apparatus; (3) the isolated condition (IC), in which a single rat is housed in a cage similar in size to SC cages without toys and placed in a quiet and dimly illuminated room. The results show that environmental influences are indeed capable of affecting cortical structure and function in rats. An increase in branching and in length of dendritic processes in pyramidal neurons in the visual cortex of adult rats can be induced by an enriched environment. This additional dendritic outgrowth in adulthood is found to occur in a fashion similar to that observed in the rat cortex during normal development.

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