Neural Plasticity and the Development of Intersensory Functioning in Bobwhite Quail (Colinus virginianus)

Abstract

Previous research has demonstrated that augmented prenatal sensory stimulation can influence the emergence of normal or species-typical patterns of intersensory perception. For example, unusually early visual experience can produce a facilitative effect on subsequent postnatal perceptual responsiveness, while substantially augmented prenatal visual stimulation can interfere with early postnatal responsiveness. In constructing a link between early experience and neuronal plasticity, it has been established that unusual visual experience can produce measurable changes in post-synaptic structures, particularly dendritic morphology, in brain areas responsible for vision. In avian species, the brain area responsible for vision is the visual Wulst, thought to be analogous to the mammalian visual cortex.

This study examined the effects of differing amounts of augmented prenatal visual stimulation on the plasticity of neurons in the visual Wulst and on subsequent postnatal visual responsiveness to maternal cues in bobwhite quail chicks. Results revealed that the pattern of neuronal organization and postnatal behavior was influenced by the amount of prenatal visual experience subjects were provided. Specifically, chicks exposed to 240 min of prenatal visual stimulation during the last 24 hr prior to hatching had neurons with significantly fewer spines/10 mm dendrite and displayed accelerated patterns of species-typical visual responsiveness. In contrast, chicks provided 900 min of prenatal visual stimulation had more complex neurons (including more spines, longer dendrites, and more branches) and failed to display normal species-specific visual responsiveness in the days following hatching. These results suggest that neuronal organization in the bobwhite Wulst proceeds in a selective fashion, molded by experience, and appears to influence early perceptual development and organization during the perinatal period