Repetitive auditory stimulation at a critical prenatal period modulates the postnatal functional development of the auditory as well as visual system in chicks (Gallus domesticus)

Abstract

The extrinsic sensory stimulation plays a crucial role in the formation and integration of sensory modalities during development. Postnatal behavior is thereby influenced by the type and timing of presentation of prenatal sensory stimuli. In this study, fertilized eggs of white Leghorn chickens during incubation were exposed to either species-specific calls or no sound. To find the prenatal critical period when auditory stimulation can modulate visual system development, the former group was divided into three subgroups: in subgroup A (SGA), the stimulus was provided during embryonic day (E)10 to E16, in SGB E17- hatching, and in SGC E10-hatching. The auditory and visual perceptual learning was recorded at posthatch day (PH) 1-3, whereas synaptic plasticity (evident from synaptophysin and PSD-95 expression), was observed at E19, E20, and PH 1-3. An increased number of responders were observed in both auditory and visual preference tests at PH 1 following stimulation. Although a decrease in latency of entry and an increase in total time spent were observed in all stimulated groups, it was most significant in SGC in auditory preference and in SGB and SGC in visual preference test. The auditory cortex of SGC and visual Wulst of SGB and SGC revealed higher expression of synaptic proteins, compared to control and SGA. A significant inter-hemispheric and gender-based difference in expression was also found in all groups. These results indicate facilitation of postnatal behaviour and synaptogenesis in both auditory and visual systems following prenatal repetitive auditory stimulation, only when given during prenatal critical period of development.

Expression of the postsynaptic scaffold PSD‐95 and development of synaptic physiology during giant terminal formation in the auditory brainstem of the chicken

“…However, several candidates of homologous genes can be found in the chicken genome (Hillier et al ., ). Therefore, the occurrence of a close PSD‐95 homologue in birds was predicted from the genomic data and has indeed been shown to occur on the mRNA level in the avian brain (Chaudhury et al ., ; Roy et al ., ) and at synaptic sites in cell cultures of chicken neurons (Honjo et al ., ). We thus expected that PSD‐95 would also occurred in the chicken CN.…”