Abstract
Abstract: :
Purpose: Previously, we demonstrated that saccadic and smooth pursuit parameters are significantly correlated among monozygotic twins and suggested that performance may be determined by both genetic and environmental factors. The purpose of the current study was to delineate the genetic influence on saccadic eye movements. Methods: Eye movements of 115 siblings from 50 families were recorded with an infra–red system in two sessions separated by several weeks. Siblings (83 females and 32 males) were healthy, young (21–30 years old), social drinkers. Two saccade tasks were used: a task for eliciting anti–saccades and a task for eliciting visually–guided saccades. Latency, peak velocity, fraction of reflexive anti–saccades, and other parameters of saccades were evaluated. Results: A genetic analyses (SOLAR software package) revealed that latency and velocity of visually–guided saccades are significantly heritable (latency: h2=0.7, p=0.006; velocity: h2=0.86, p=0.002). Velocity of the anti–saccades was also significantly heritable (h2=0.65, p=0.01), while latency and fraction of reflexive anti–saccades were marginally heritable (latency: h2=0.4, p=0.09; fraction of reflexive anti–saccades: h2=0.4, p=0.08). The test–retest reliability of saccadic parameters between sessions (Pearson correlation coefficient) was on average 0.6, p<0.01. Conclusions: The study confirmed the genetic influence on saccadic performance, demonstrated high test–retest reliability of saccadic parameters and suggested that saccadic performance may serve as a biological marker or an indicator of genetic liability.
Keywords: eye movements: saccades and pursuits • genetics