Molecular Genetics and the Development of Reflexive Visual Attention
Dannemiller, James L.
Doctor of Philosophy
This study elucidates genetic influences on the development of reflexive attention. Reflexive attention refers to processes that rapidly shift attention, typically from one location in space to another (such as to an object that appears suddenly or moves). Our previous work has shown that normal adults differ by genotype on a reflexive attention task (Lundwall, Guo & Dannemiller, 2012). The current study attempts to show that normal children show similar genotypic differences. Differences in reflexive attention by genotype are not certain because gene expression and experience differ in children compared to adults. However, understanding association by genotype could be important to the early identification and treatment of attention-related disorders commonly diagnosed in childhood (e.g., attention deficit disorder; ADHD). Here I follow-up with children (aged nine -16 years; N = 332) who participated as infants in visual attention studies (see Dannemiller, 2004). I investigate genetic associations with reflexive attention measures at both time points as well as associations with stress, health, and academic performance. The genetic markers (i.e., APOE, BDNF, CHRNA4, COMT, DRD4, HTR4, IGF2, MAOA, SLC5A7, SLC6A3, and SNAP25) are related to brain development and/or to the availability of neurotransmitters such as acetylcholine, dopamine, or serotonin. One of the more interesting findings is that markers on CHRNA4, DRD4, IGF2, and MAOA predict the trajectory of the development of reflexive attention from infancy to childhood. Another interesting finding is that, unlike with our previous study with adults where cost dim was most sensitive to individual differences, with this child sample cost bright (the response time cost of a single bright, contralateral pre-cue) was associated with markers on BDNF, MAOA, and SNAP25. These genes are associated with brain growth, neurotransmitters such as dopamine, and neurotransmitter release into the synapse, respectively. A specific marker (rs6323) on MAOA was associated with seven child attention-task outcomes. From these and related results, I conclude that individual differences in reflexive attention and its development are related to several genetic markers including dopaminergic genes (implicated in disorders of attention such as ADHD).