Relating dopaminergic and cholinergic polymorphisms to spatial attention in infancy.

Early selective attention skills are a crucial building block for cognitive development, as attention orienting serves as a primary means by which infants interact with and learn from the environment. Although several studies have examined infants' attention orienting using the spatial cueing task, relatively few studies have examined neurodevelopmental factors associated with attention orienting during infancy. The present study examined the relationship between normative genetic polymorphisms affecting dopamine and acetylcholine signaling and attention orienting in 7-month-old infants during a spatial cueing task. We focused on 3 genes, including the CHRNA4 C¹⁵⁴⁵T SNP (rs10344946), DAT1 3'UTR VNTR, and COMT Val¹⁵⁸Met SNP (rs4680), as previous adult research has linked spatial attention skills to these polymorphisms. Behavioral measures included both facilitation of orienting at the cued location as well as inhibition of return (IOR), in which attention orienting is suppressed at the cued location. Results indicated that COMT Val carriers showed robust IOR relative to infants with the Met/Met genotype. However, COMT was unrelated to infants' facilitation responses, and there were no effects of CHRNA4 or DAT1 on either facilitation or IOR. Overall, this study suggests that variations in dopamine signaling, likely in prefrontal cortex, contribute to individual differences in orienting during early development.