Developmental alterations in brain network asymmetry in 3- to 9-month infants with congenital sensorineural hearing loss

Auditory exposure plays a crucial role in shaping brain development, but little is known about whether and how an initial lack of auditory exposure might disrupt the development of functional network lateralization. We addressed this issue by acquiring functional near-infrared spectroscopy data from infants aged 3 to 9 months with congenital sensorineural hearing loss (SNHL). The SNHL infants showed efficient small-world characteristics within each hemisphere. However, unlike typically developing controls, who showed an age-related leftward lateralization of network efficiencies, SNHL infants did not exhibit the emergence of hemispheric asymmetry. Intriguingly, lateralization of frontal efficiency was preserved in SNHL infants with mild hearing loss but declined significantly with increasing severity of hearing impairment. These findings suggest that even SNHL infants with some residual hearing experience disruption in the development of functional lateralization. This underscores the importance of providing early auditory access to SNHL infants to support robust functional integration during early development.