Neural Correlates of Sociocognitive Processing in Infants with Congenital Visual Impairment

Background:  

Young children with congenital profound or severe visual impairment (VI) have a high risk of developing difficulties in social communication and interaction. However the electrophysiological mechanisms underlying socio-cognitive processes in infants with VI remains unknown. The Subject’s Own Name (SON) is a powerful and unique auditory social stimulus; behavioural, imaging and ERP studies in healthy infants have shown that the SON response can be detected as early as 4-5 months (Mandel, 1995, Grossmann et al., 2010; Blasi et al., 2011, Lloyd-Fox et al., 2012). The SON is considered a reliable measure of socio-cognitive processing (Carmody et al., 2006) and has the potential to demonstrate abnormalities in atypical populations.

Objectives:

We set out to examine ERP responses to the SON in infants with VI at 1 year of age compared to age-matched typically sighted controls. Based on previous SON ERP findings, we predicted that the SON would elicit greater amplitudes compared to the other name in typically sighted infants. We predicted atypical ERP responses in infants with VI compared to sighted controls based on the evidence that children with VI have socio-cognitive difficulties (Dale & Salt, 2008).

Methods:  

23 infants with severe and profound VI (mean 12.7 ± 2.5 months) with ‘simple’ peripheral disorders of the congenital visual system and 14 age-matched typically sighted infants (mean age mean 12.5 ± 2.4 months) underwent ERP recording using a 128-channel EGI Sensor Net. SONs and ‘other’ names spoken by the mother’s voice were presented in an equiprobable design at 70 dB intensity. Two ERP components were identified by selecting peak amplitudes (± 30 ms) of grand averages per group: P300 (213-273 ms) component and N500 (484-544 ms) component.

Results:  

Repeated-measures ANOVAs revealed no effect of the SON on P300 responses in the infants with VI or in the typically sighted control group (all p’s >.05). A significantly larger N500 amplitude (greater response) for the SON compared to Other name at frontal and central sites was observed (Name x Location: F(3,39.1) = 2.5, p<0.05) in the typically sighted control group. However in the infants with VI, no significant name effect on the N500 component was found, with similar magnitude of response to both SON and other name observed (p>.05).

Conclusions:  

This finding for the N500 component in typically sighted group was consistent with Parise et al. (2010), who also found significantly larger negative-going amplitudes (N200-600) at frontal and central sites in response to the SON in 5-month-old typically sighted infants. However, infants with VI showed an atypical response to the SON, showing a reduced SON effect and not localized in the same sites, compared to the typically sighted control group. Therefore, as early as 1 year of age, infants with congenital VI appear to be processing socially salient information differently to age-matched sighted infants and we can detect this at neural level. Further investigation will identify if the ERP SON response acts as an early biomarker for later socio-communicative difficulties in children with VI who are most at risk of emerging autism.