Abstract
Purpose :
Volitional saccades toward and in a direction opposite to a remembered target location have been quantified as a means of assessing working memory and response inhibition capacity. In the present study, we sought to establish how eye movement latency for remembered antisaccades systematically changes over a range of delays after the target location has been cued and remembered. Accordingly, this approach allowed for understanding of the temporal constraints of how working memory and response inhibition affect volitional eye movements.
Methods :
Eight subjects, (mean age=31yr ±16), six females) participated. While fixating at a central white target, a peripheral target appeared for 100ms and then disappeared. The subject made an antisaccade (eye movement in opposite direction) to the remembered target location only after the visual cue appeared (change of white central target to black). The visual delay cue appeared after delay periods of 0, 0.125, 0.250, 0.500, 1.0 and 2s. Eye movements were measured using GazepointGP3 eye tracker with a sampling rate of 150Hz. The remembered antisaccade latency, disinhibitions (eye movements incorrectly made prior to the visual display cue during delay) and directional errors (eye movements incorrectly towards the peripheral target after the delay) were determined.
Results :
There was a significant effect of duration of delays on latencies of remembered antisaccade (F (5,30) = 6.3, p = 0.0004). Mean saccadic latency was longer for 0 delay (Mean =471.9±136msec) compared to 0.250 (Mean =337.1±88msec), 0.500 (Mean = 367.6±70msec), 1.00 (Mean=306.0±24msec) and 2.00 (Mean =341.7±75msec) but not for 0.125sec (Mean=442.1±122msec). The number of disinhibitions (%) and directional errors (%) did not show significant difference with the duration of delay period.
Conclusions :
Saccades opposite to a remembered target location showed longer latencies with shorter delays despite showing no effect on disinhibitions and directional errors. The delay period provides enough time to plan and initiate correct antisaccades by retrieving the information on target location from working memory and suppressing the reflexive saccades towards the target. This eye movement task may be a useful diagnosing tool to understand the neural integrity of normal brain functions and in neurological conditions.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.