The Effect of Long Duration Postnatal Odour Exposure on the Development of the Rat Olfactory Bulb

Abstract

In the last 20 years it has been clearly demonstrated that experience can have an effect on the structure and function of the brain (Harlow and Harlow 1964; Diamond et al. 1964; Rosenzweig 1971). In a recent review, Walsh (1981) cited evidence which showed that exposing young animals to enriched or impoverished environments produced a wide range of anatomical modifications to the brain. These included changes in brain weight and size, number and size of neurons, and the number of synapses and dendritic branches. Studies using exposure to restricted sensory environments have yielded important information about the structure, function and development of parts of the central nervous system (Wiesel and Hubel 1963; Blakemore 1973; Webster and Webster 1977). For example, Blakemore (1973) described how the orientation neurons of the visual cortex of kittens could be tuned to respond predominantly to vertical lines, by exposing visually deprived 4-week-old kittens to an environment of black and white vertical stripes for 6 h. An analogous effect was found in the olfactory system by Doving and Pinching (1973). They found that exposing 14-day-old rats to a single odorant for 2 or more weeks caused mitral cells in specific regions of the olfactory bulb to appear smaller and more deeply stained than in control rats.