theta EROs and genotypic variants of 21 single nucleotide polymorphisms (SNPs) from cholinergic genes CHRM2, CHRNA3, CHRNA5, CHRNA6, CHRNB1, CHRNB3, and CHRNB4, measured by effect sizes of genotypic covariates in the regression analysis, were found to vary with age, sex, task modality, and scalp locality. Seven of the SNPs had significant effects with considerable age spans for some sex-modality combination. Eight of the SNPs had significantly different effects in males and females with considerable age spans for either one or both modalities. No SNP at any age-modality combination had significant effects in the same direction for males and females. Principal component analysis (PCA) of the genotypic profiles (vector of values of genotypic associations) of phenotypes identified the age variation in genotypic profiles which discriminate sex, modality, and locality differences in phenotypes. The physiological processes responsible for large sex differences in genotypic effect on brain function have yet to be determined.
