Three Strategies for Prospective Mapping of Neurphysiological Measures on to Behavioural Outcomes

Background: It is suggested that neurophysiological measures are more sensitive than behavioral measure in signaling early brain atypicality, which in some infants leads to an autism diagnosis. Notwithstanding the promise of such measures as predictors of clinical outcomes, researchers have also advocated the use of dimensional intermediate phenotypes, viewed as more closely aligned to the genotype than complex clinical characterization. Specifically, measures of quantitative traits associated with ASD are though to be better candidates for gene mapping relative to diagnostic classification. The assumption here is that diagnosed forms of ASD, which are themselves highly variable, are extremes of what is otherwise typical individual variation.

Objectives: We contrast three strategies for mapping of infant brain function measures on to later behavioral outcomes within the same longitudinal cohort. The first strategy is mapping between brain function measures and clinically defined outcomes in toddlerhood. The second and third strategies involve mapping the same infant brain function measures onto emerging atypical or alternatively typical variation in social and communicative skills.

Methods: Participants were from the British Autism Study of Infant Siblings (BASIS). One hundred and four infants (54 high-risk sibs and 50 low-risk controls) were included in the analysis. When aged between 6 and 10 months, ERPs were recorded while the infants viewed dynamic images of females shifting their gaze towards (directed) or away from (averted) the infant. Outcome measures at 2- and 3-years of age included a range of standardized measures combined with expert clinical judgment to ascertain outcome classification.

Results: Relative to the control group, the high-risk siblings group showed both similarities and differences in the amplitude and latency of components related to gaze processing. Variation in individual infant’s ERP response characteristics was correlated with outcome measures irrespective of the strategy used. Different strategies reveal that a range of brain function measures capture complementary aspects of the emerging behavioral phenotype.

Conclusions: As a group, infants at-risk for autism show differences in certain neural components related to the processing of eye gaze. Moreover, individual differences in the infant ERP could be mapped onto behavioral characteristics of the same infants when they reach toddlerhood. The findings help to highlight the potential scientific and clinical utility of infant ERP measures.

The BASIS Team in alphabetical order: Baron-Cohen, S., Bedford, R., Bolton, P., Chandler, S., Fernandes, J., Garwood, H., Gliga, T., Hudry, K., Pasco, G., Tucker, L., Volein, A.