Abstract
Purpose:
Orientation is a fundamental property of visual scene elements. The perception of orientation is supported by orientation-tuned neurons, which are organized into functional columns in visual cortex. Cortical orientation maps develop under genetic control, and genetic factors contribute to individual differences in their configuration. However, it is unknown whether genetic polymorphisms actually contribute to individual differences in the ability to detect orientation.
Methods:
In a cohort of 1060 healthy young adults, we measured psychophysical thresholds for visual discrimination of orientation, which was introduced into random dot textures by modulating density along an oblique axis (gratings), or by incorporating coherently oriented dot pairs (Glass patterns). We then assessed, under a linear allelic dosage model, univariate and multivariate associations of the two behavioral phenotypes with 642 758 single-nucleotide polymorphism (SNP) markers distributed throughout the genome.
Results:
The strongest univariate (P = 5.9 × 10−8; Pfamilywise = .02) and multivariate (P = 1.1 × 10−7; Pfamilywise = .04) associations were observed between orientation discrimination performance and a marker in the gene HEBP1. In addition, there were suggestive associations with regulatory elements believed to modulate expression of genes encoding gap junction proteins (GJB2 and GJA3), cytochrome P450 enzymes (CYP26C1 and CYP26A1) and netrins (NTN4).
Conclusions:
The primary genetic associate of orientation discrimination, HEBP1, encodes an evolutionarily ancient heme-binding protein with prenatal expression in neocortex. Several secondary associates have known roles in the development of cortical architecture: GJB2 expression is critical to the establishment of functional orientation columns; CYP26C1 and CYP26A1 encode hemoproteins that jointly regulate anteroposterior brain patterning during embryonic development; and NTN4 encodes an axonal guidance molecule that is highly expressed in cortex. Our results thus point to a pathway from genetic mechanisms to behavior via structure and function: the associated genes may influence the ability to detect orientation in visual textures by affecting the functional organization of visual cortex.
Keywords: 539 genetics •
641 perception •
755 visual cortex