Using Eye Movements to Establish a Normative Database of Control Participants Across the Lifespan
Saccades , Oculomotor System , Development , Aging , Eye Movements
As the brain develops and ages, cognitive abilities (e.g., attention and memory) undergo significant functional fluctuations. In order to differentiate neuropathology from natural changes that occur due to development and aging, the goal of our study is to develop an understanding of changes in cognitive control that occur across the lifespan. The oculomotor system is an ideal model to probe cognitive function through the analysis of saccadic eye movements. We used a video-based eye tracker capable of measuring various saccade metrics on an interleaved pro- and anti-saccade task in healthy participants 5-85 years of age. The interleaved pro- and anti-saccade task requires the generation of pro-saccades (automatic eye movements toward a salient stimulus) and/or anti-saccades (voluntary eye movements away from a salient stimulus) depending upon a visual colour instruction. Participant head position was stabilized using a fixed head mount and participants sat in front of a computer screen to conduct the task. Our results show that individuals between 17 and 29 years of age outperformed younger and older participants by generating the fastest correct pro- (Mean = 146ms to 160ms) and anti-saccades (Mean = 225ms to 232ms). Participants between 21 and 29 years of age generated the fewest anti-saccade direction errors (Mean = 13.3%), which occur when an automated pro-saccade is initiated towards the target. Younger children (5-13 years-old) and older adults (50-85 years-old) had the slowest anti-saccade reaction times (Mean = 285ms to 339ms and 265ms to 290ms, respectively). Among younger participants (5-16 years-old), direction error rates decreased with age (Mean = 60.3% to 29.8%). Taken together, these results demonstrate strong developmental- and age-related effects in participant performance, reflecting maturation and deterioration of the nervous system. This study provides valuable insight into the natural oculomotor changes that take place across the lifespan, providing a foundation for future comparisons between clinical, preclinical and healthy populations.