Summary
1. We studied saccades to briefly flashed targets in 8 human subjects. The target flash occurred (i) during smooth pursuit (“ramp-flash”), (ii) just before a saccade to another target (“step-flash”), or (iii) during steady fixation (“flash only”). All lights were extinguished after the target flash so that smooth pursuit or saccadic eye movements occurred during the interval of complete darkness between the target flash and the saccade to it. We compared these saccades to those made without intervening eye movement (flash only), and quantified the extent to which the saccadic system compensated for the change in eye position that occurred during the dark interval. 2. Saccades to control flashes were reasonably accurate (mean gain 0.87) and consistent. Compensation for the intervening eye movement in the ramp-flash and step-flash paradigms was highly variable from trial to trial. On average, subjects compensated for 27% of the intervening pursuit eye movement on ramp-flash trials and for 58% of intervening saccadic movement on step-flash trials. 3. Multiple regression analysis showed that the variability did not depend on factors such as variations in underlying saccadic gain, response latency, timing of stimuli or size of the required response. We conclude that this variability is intrinsic to saccadic responses that require the use of an eye position signal. 4. These results show that an eye position signal is available to the saccadic system but that this signal has low fidelity. The high variability and low fidelity of the eye position signal suggest that the saccadic system does not normally operate in spatial coordinates, which require the use of an accurate eye position signal, but rather in retinal coordinates.
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References
Albano JE, Wurtz RH (1982) Deficits in eye position following ablation of monkey superior colliculus, pretectum, and posterior-medial thalamus. J Neurophysiol 48: 318–337
Becker W (1988) Metrics of saccades. In: Wurtz RH, Goldberg ME (eds) The Neurobiology of saccadic eye movements. Reviews of oculomotor research, Vol III. Elsevier, Amsterdam pp 13–67
Becker W, Jürgens R (1979) An analysis of the saccadic system by means of double step stimuli. Vision Res 19: 967–983
Bock O (1986) Contribution of retinal versus extraretinal signals towards visual localization in goal-directed movements. Exp Brain Res 64: 476–482
Bridgeman B, Hendry D, Stark L (1975) Failure to detect displacement of the visual world during saccadic eye movements. Vision Res 15: 719–722
Carpenter RHS (1988) Movements of the eyes, 2edn. Pion, London
Dassonville P, Schlag J, Schlag-Rey M (1990) A damped representation of eye position is used in oculomotor localization. Soc Neurol Abstr 16: 1085
Gellman RS, Fletcher WA (1990) Poor “spatial” signal in human saccadic system. Soc Neurol Abstr 16: 1083
Hallett PE, Lightstone AD (1976a) Saccadic eye movements toward stimuli triggered by prior saccades. Vision Res 16: 88–106
Hallett PE, Lightstone AD (1976b) Saccadic eye movements to flashed targets. Vision Res 16: 107–114
Hansen RM, Skavenski AA (1977) Accuracy of eye position information for motor control. Vision Res 17: 919–926
Hansen RM, Skavenski AA (1985) Accuracy of spatial localizations near the time of saccadic eye movements. Vision Res 25: 1077–1082
Hays AV, Richmond BJ, Optican LM (1982) A UNIX-based multiple process system for real-time data acquisition and control. WESCON Conf Proc 2: 1–10
Honda H (1989) Perceptual localization of visual stimuli flashed during saccades. Percept Psychophys 45: 162–174
Jeannerod M (1983) How do we direct our actions in space?. In: Hein A, Jeannerod M (eds) Spatially oriented behaviour. Springer Berlin, Heidelberg, New York p 1–13
Matin L, Matin E, Pearce DG (1969) Visual perception of direction when voluntary saccades occur: I. Relation of visual direction of a fixed target extinguished before a saccade to a flash presented during a saccade. Percept Psychophys 5: 65–80
Mays LE, Sparks DL (1980) Saccades are spatially, not retinocentrically, coded. Science 208: 1163–1165
McIlwain JT (1988) Effects of eye position on electrically evoked saccades: a theoretical note. Vis Neurosci 1: 239–244
McKenzie A, Lisberger SG (1986) Properties of signals that determine the amplitude and direction of saccadic eye movements in monkeys. J Neurophysiol 56: 196–207
Robinson DA (1975) Oculomotor control signals. In: Lennerstrand G, Bach-y-Rita P (eds) Basic mechanisms of ocular motility and their clinical implications. Pergamon Press, Oxford pp 337–374
Schiller PH, Sandell JH (1983) Interactions between visually and electrically elicited saccades before and after superior colliculus and frontal eye field ablations in the rhesus monkey. Exp Brain Res 49: 381–392
Schiller PH, Stryker M (1972) Single-unit recording and stimulation in superior colliculus of the alert rhesus monkey. J Neurophysiol 35: 915–924
Schlag J, Schlag-Rey M, Dassonville P (1990) Saccades can be aimed at the spatial location of targets flashed during pursuit. J Neurophysiol 64: 575–581
Skavenski AA, Steinman RM (1970) Control of eye position in the dark. Vision Res 10: 193–203
Sparks DL, Mays LE (1983) Spatial localization of saccade targets. I. Compensation for stimulation-induced perturbations in eye position. J Neurophysiol 49: 45–63
Sparks DL, Mays LE, Porter JD (1987) Eye movements induced by pontine stimulation: interaction with visually triggered saccades. J Neurophysiol 58: 300–318
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Gellman, R.S., Fletcher, W.A. Eye position signals in human saccadic processing. Exp Brain Res 89, 425–434 (1992). https://doi.org/10.1007/BF00228258
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DOI: https://doi.org/10.1007/BF00228258