Abstract
Saccadic suppression is an important neuronal mechanism for visual stability. Healthy aging is characterized by a loss of visual contrast sensitivity and prolonged saccadic latencies, but little is known about age effects on saccadic suppression with exception of a single study showing greater suppression in children and adolescents (Bruno et al., J. Neurophysiology, 2006). We used an adaptive staircase procedure to measure contrast sensitivity for the detection of a luminance line stimulus flashed 8 ms above or below the horizontal midline. Thresholds were measured during central fixation and 15 ms after the onset of a 10° horizontal saccade to the left or right. Eye position signals were recorded with an EyeLink 2000 system. 49 observers from 8 to 78 years participated, with 25 younger observers (average 26.4y) and 24 older observers (average 64.6y). All subjects had normal or corrected to normal vision. As expected, luminance contrast thresholds increased with age (5.3% for the younger group vs 8.0% for the older group). The comparison of younger and older subjects revealed a significant age effect on saccadic suppression. Suppression was 59% for the younger and 71% for the older group (t47= 3.03; p< 0.01). A linear regression showed an increase in saccadic suppression of 3% every 10 years. We found a significant increase with age for saccadic suppression of luminance, but with 3% per decade it is relatively small in magnitude. It is different in sign from the decrease in surround suppression reported earlier (Betts et al., JoV 2009). Therefore mechanisms for saccadic suppression seem to be quite stable during healthy aging.
Acknowledgement: Deutsche Forschungsgemeinschaft SFB/TRR 135