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James Dannemiller; A Gene X Gene Interaction Between COMT and DAT1 in the Attentional Cost of an Invalid Visual Cue. Journal of Vision 2012;12(9):671. doi: 10.1167/12.9.671.
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The reaction time to a simple target can be lengthened reliably (relative to a neutrally cued baseline) by preceding that target with a briefly flashed cue that appears at a different location in the visual field (Posner, Snyder, & Davidson, 1980). The additional steps of disengaging and shifting attention from its current focus to another location require extra time, leading to longer reaction times on invalidly cued trials. Using a sample of 161 observers across the age range from 18 to 61 years, we have previously shown that the additional time required to respond on invalid trials with a cue-target SOA of 150 msec, especially when a low luminance cue is used, depends on an observer's genotype on certain dopaminergic genes (COMT, DAT1; Lundwall, Guo & Dannemiller, 2010). On both of these genes, larger attentional costs are associated with genotypes having less available dopamine. We now show using a novel classification and regression tree (CART) analysis with appropriate 10-fold cross-validation that the effects of these two genes on the attentional costs produced by an invalid, dim cue are not additive. The final decision tree model has two splits. Split 1 divides the complete sample using the COMT SNP: [GG] vs. [AG or AA] with the GG genotype (less available dopamine) showing a mean of 14 msec larger attentional cost. Split 2 then further subdivides only the subgroup of COMT observers having more available dopamine [AG or AA] by their DAT1 genotype: [6R/6R] vs. [5R/6R or 5R/5R] with the 6R/6R genotype (less available dopamine) showing a mean of 16 msec larger attentional costs. It is only the subjects with more available dopamine based on their COMT genotypes whose attentional costs are further significantly differentiated by their DAT1 genotype. These results represent a novel gene x gene interaction in cued visual orienting.
Meeting abstract presented at VSS 2012
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