The Influence of Briefly Presented Randomized Target Motion on the Extraretinal Component of Ocular Pursuit

Abstract

We assessed the ability to extract velocity information from brief exposure of a moving target and sought evidence that this information could be used to modulate the extraretinal component of ocular pursuit. A step-ramp target motion was initially visible for a brief randomized period of 50, 100, 150, or 200 ms, but then extinguished for a randomized period of 400 or 600 ms before reappearing and continuing along its trajectory. Target speed (5–20°/s), direction (left/right), and intertrial interval (2.7–3.7 s) were also randomized. Smooth eye movements were initiated after about 130 ms and comprised an initial visually dependent component, which reached a peak velocity that increased with target velocity and initial exposure duration, followed by a sustained secondary component that actually increased throughout extinction for 50- and 100-ms initial exposures. End-extinction eye velocity, reflecting extraretinal drive, increased with initial exposure from 50 to 100 ms but remained similar for longer exposures; it was significantly scaled to target velocity for 150- and 200-ms exposures. The results suggest that extraretinal drive is based on a sample of target velocity, mostly acquired during the first 150 ms, that is stored and forms a goal for generating appropriately scaled eye movements during absence of visual input. End-extinction eye velocity was significantly higher when target reappearance was expected than when it was not, confirming the importance of expectation in generating sustained smooth movement. However, end-extinction eye displacement remained similar irrespective of expectation, suggesting that the ability to use sampled velocity information to predict future target displacement operates independently of the control of smooth eye movement.

Keep your eyes on the ball: smooth pursuit eye movements enhance prediction of visual motion

“…This finding is not unexpected. In line with Barnes and Collins (2008), we found that a sampling period of 100 ms was sufficient to produce a reliable smooth pursuit response in a substantial number of all trials with pursuit instruction (73%) but still in fewer trials than for longer presentation durations (300 ms: 91%, 500 ms: 93%). The decrease in pursuit performance at the shortest presentation duration during the last analysis interval might also reflect the small amount of pursuit executed when targets disappeared before the onset of pursuit (pursuit latency: M ϭ 150.8, SD ϭ 2.2; interestingly, latency was similar for longer presentation durations, 300 ms: M ϭ 150.2 Ϯ 4.1, 500 ms: M ϭ 149.9 Ϯ 4.2), and when the analysis interval started at ϳ350 ms (ϳ150 ms latency ϩ 200 ms until start of analysis interval) after the targets disappeared.…”

Evidence for a Link Between the Extra-Retinal Component of Random-Onset Pursuit and the Anticipatory Pursuit of Predictable Object Motion

“…Six human subjects, who had all participated in our earlier experiment (Barnes and Collins 2008), took part with voluntary consent. They had no known neurological or oculomotor problems and had normal or corrected-to-normal vision.…”

“…The starting point for this investigation was a recent experiment in which the effects of expectation were shown to influence the development of the extra-retinal component of random-onset pursuit (Barnes and Collins 2008). In one task (referred to as mid-ramp extinction), a moving target, randomized in speed, direction, and timing, was initially exposed for a brief period (50 -200 ms) prior to extinction for Յ600 ms and subsequent reappearance.…”

Disappearance of the inversion effect during memory-guided tracking of scrambled biological motion

“…In other words, the inversion effect disappeared only when the scrambled biological motion was occluded. According to Barnes and Collins (2008), when there is a complete loss of the visual feedback signal after target disappearance, smooth pursuit continues at a reduced gain and is maintained by extraretinal information processing. It has been recognized that the extraretinal input is a more complex arrangement reflecting velocity-coded information (Barnes & Asselman, 1991;Bennett & Barnes, 2004;Churchland et al, 2003), which is influenced by cognitive factors such as perception, expectation, and attention (Beutter & Stone, 1998;Madelain & Krauzlis, 2003;Pola & Wyatt, 1997;Tanaka & Lisberger, 2001).…”

“…However, the predictive mechanism in ocular pursuit during transient occlusion was influenced by such low-level factors as pre-and postocclusion target velocity (Becker & Fuchs, 1985;Mrotek & Soechting, 2007;Orban de Xivry et al, 2006) and preocclusion viewing time (Bennett, Orban de Xivry, Barnes, & Lefèvre, 2007;Orban de Xivry, Missal, & Lefèvre, 2009). According to Barnes and Collins (2008), during sustained pursuit of a continuously visible target, retinal and extraretinal signals work together to maintain a stable response with high gain. Retinal input comes from direct feedback of visual motion signals and has an inherent visuomotor delay of 80-100 ms (Carl & Gellman, 1987).…”