The effect of prenatal sensory stimulation on the parvalbumin neurons in entopallium and visual Wulst

Conserved genetic mechanisms participate in developing brain asymmetries in vertebrates, but the effect of prenatal sensory stimulation on lateralised neural circuits is less understood. In birds, lateralisation emerges from the interaction of genetic factors and prenatal experience. Light exposure during a sensitive stage of embryonic development asymmetrically stimulates the two eyes, causing lateralised visual functions. However, nothing is known about its effects on the cell composition of visual areas. Here, we investigated the effects of sensory stimulation on the neuroanatomy of the two primary visual areas of the bird telencephalon (entopallium and visual Wulst) by analysing the density of parvalbumin neurons in domestic chicks. We found that both areas are sensitive to light incubation, showing denser parvalbumin neurons in the left hemisphere of light-incubated chicks than dark-incubated chicks. Light-incubated chicks also showed denser parvalbumin neurons in the left hemisphere than in the right one. In contrast, no asymmetry was present in dark-incubated chicks. We show that prenatal experience influences neural compositions in the telencephalon.