Spatial localization of saccade targets. I. Compensation for stimulation-induced perturbations in eye position.

Sparks, David L.; Mays, Lawrence E.

doi:10.1152/jn.1983.49.1.45

Cited by 298 publications

(168 citation statements)

References 34 publications

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“…Generation of accurate corrective saccades, with latencies less than the latency of visual feedback, has also received much empirical and theoretical interest (Hallett and Lightstone 1976a;Sparks and Mays 1983) because such correction is thought to require use of a movement vector, which must be updated for the change of eye position produced by the erroneous saccade. One mechanism hypothesized to account for fast on-line error correction may be a comparison of the spatial location of the goal with the current eye displacement.…”

Section: Parallel Programming During Error Correctionmentioning

confidence: 99%

Control of Predictive Error Correction During a Saccadic Double-Step Task

Sharika¹,

Ramakrishnan²,

Murthy³

2008

Journal of Neurophysiology

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Sharika KM, Ramakrishnan A, Murthy A. Control of predictive error correction during a saccadic double-step task. J Neurophysiol 100: 2757-2770, 2008. First published September 24, 2008 doi:10.1152/jn.90238.2008. We explored the nature of control during error correction using a modified saccadic double-step task in which subjects cancelled the initial saccade to the first target and redirected gaze to a second target. Failure to inhibit was associated with a quick corrective saccade, suggesting that errors and corrections may be planned concurrently. However, because saccade programming constitutes a visual and a motor stage of preparation, the extent to which parallel processing occurs in anticipation of the error is not known. To estimate the time course of error correction, a triple-step condition was introduced that displaced the second target during the error. In these trials, corrective saccades directed at the location of the target prior to the third step suggest motor preparation of the corrective saccade in parallel with the error. To estimate the time course of motor preparation of the corrective saccade, further, we used an accumulator model (LATER) to fit the reaction times to the triple-step stimuli; the best-fit data revealed that the onset of correction could occur even before the start of the error. The estimated start of motor correction was also observed to be delayed as target step delay decreased, suggesting a form of interference between concurrent motor programs. Taken together we interpret these results to indicate that predictive error correction may occur concurrently while the oculomotor system is trying to inhibit an unwanted movement and suggest how inhibitory control and error correction may interact to enable goal-directed behaviors.

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Section: Parallel Programming During Error Correctionmentioning

confidence: 99%

Control of Predictive Error Correction During a Saccadic Double-Step Task

Sharika¹,

Ramakrishnan²,

Murthy³

2008

Journal of Neurophysiology

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“…For example, the amount of electrical stimulation needed to evoke a saccade in the SC increases if a subject's fixation is required to be more intent (Schiler & Sandell, 1983;Sparks & Mays, 1983). This inhibition seems to have at least two sources: the substantia nigra pars reticulata (SNr) (Hikosaka & Wurtz, 1983d) and the 'rostral region of the superior colliculus (Munoz & Wurtz, 1992).…”

Section: Why Consider a Possible Physiological Basis For Express Saccmentioning

confidence: 99%

Express saccades elicited during visual scan in the monkey

Sommer

1994

Vision Research

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Monkeys trained to saccade to visual targets can develop separate "express" and "regular" modes in their distribution of saccadic latencies. The purpose of this study was to determine whether this occurs under more natural viewing conditions, when targets are suddenly presented in a structured visual field during visual scan. It was found that scanning saccades stopped appearing 60 msec after a target's onset, and subsequent saccades, which were directed toward the suddenly appearing target, had a bimodal distribution of latencies. Express saccades were more likely to occur as the target was presented later in a fixation. Regular mode saccades were more likely to occur with longer target durations. Scanning saccades made to stimuli of the structured visual field always had unimodal inter-saccadic interval distributions. All these effects were apparent after only 2-3 days of training. These findings, taken together with recent physiological results, suggest that the visuomotor cells of the superior collculus mediate latency bimodality.

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“…This result strongly supports a scheme with independent control of amplitude and direction, such as the rate noise version of our model (see also Becker & Jiirgens, 1979), and cannot be explained by the pure location-jitter version. Since the extreme versions of the model can explain some saccade amplitude depends on electrical-current strength (Sparks & Mays, 1983).…”

Section: Test Of the Two Modelsmentioning

confidence: 99%

“…Electrical stimulation studies in the deeper layers of the monkey superior colliculus, currently performed in our laboratory (manuscript submitted), reveal that lowering the electrical stimulation strength strongly influences the amplitude of the forthcoming saccades (cf Sparks & Mays, 1983) but not their direction. It is also a consistent finding that repeated stimulation with a constant current strength yields elliptical saccade endpoint histograms just as we found in the present behavioural experiments.…”

Section: Test Of the Two Modelsmentioning

confidence: 99%

Scatter in the metrics of saccades and properties of the collicular motor map

1989

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Abstract-Saccades, elicited by an identical visual stimulus in repeated trials, exhibit a certain amount of amplitude and direction scatter. The present paper illustrates how this scatter may be used to discern various properties of the subsystem that determines the metrics of a saccade. It is found in humans that scatter along the eccentricity axis is consistently more pronounced than along the direction axis. The ratio of amplitude scatter and direction scatter is approximately constant for all target positions tested. In addition, the absolute amount of scatter increases roughly linearly with target eccentricity but does not depend on target direction. We have explored whether these findings may reflect noisy variations in the neural representation of the saccade vector at the level of the collicular motor map. There are good reasons to assume that the motor map, at least in the monkey, (1) is organized in polar coordinates, (2) has a nonhomogeneous (roughly logarithmic) representation of saccade amplitude and (3) is anisotropic in nature (Robinson, 1972; Ottes, Van Gisbergen & Eggermont, 1986;Van Gisbergen, Van Opstal & Tax, 1987). To account for the intertrial variability in saccades, we have slightly extended an existing model for the collicular role in the coding of saccade metrics by allowing small variations in both the total amount and the location of the collicular population activity. We discuss how such noisy variations at the level of the motor map would be expressed in the metrics of saccadic responses and consider alternative models which could explain our data.

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Spatial localization of saccade targets. I. Compensation for stimulation-induced perturbations in eye position.

Cited by 298 publications

References 34 publications

Control of Predictive Error Correction During a Saccadic Double-Step Task

Control of Predictive Error Correction During a Saccadic Double-Step Task

Express saccades elicited during visual scan in the monkey

Scatter in the metrics of saccades and properties of the collicular motor map

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