A short-latency transition in saccade dynamics during square-wave tracking and its significance for the differentiation of visually-guided and predictive saccades

SummarySeveral recent studies indicate that saccades elicited in the absence of a visual target are slower than visually-guided movements of the same size. In addition, we have shown earlier that the slower saccades observed in two different paradigms had more asymmetrical (skewed) velocity profiles. Recently, it has been reported that predictive saccades are also slower. An interesting question, which arises if predictive and visually-guided saccades do have different velocity profiles, is whether the time when the transition occurs can be determined from their dynamic characteristics (peak velocity and skewness) and whether this transition latency can serve as a plausible criterion for distinguishing predictive and visually-guided saccades. To investigate this problem, visually-guided and predictive saccades were elicited by various experimental paradigms in six normal human subjects. Eye movements were measured using the double-magnetic induction method. We found that scatter plots of normalized peak velocity against latency showed an abrupt, small (10–20%) increase at a surprisingly short latency (about 30–70 ms). Furthermore, skewness of the saccadic velocity profile showed a significant drop at comparable latencies. There was a tight correlation between the peak velocity and skewness transition latencies of each subject. Considering the shape of the latency histograms in this and earlier studies, as well as other data, it appears unlikely that these very short transition latencies demarcate the distinction between predictive and fully visually-guided saccades. Instead, we suggest the possibility that the visual stimulus can speed up saccades at an earlier time than it can initiate and guide them. If this is the case, the very short transition latencies (mean: about 50 ms) probably represent the sum of afferent and efferent pure time delays in the system and do not include the time needed for the computation of saccade metrical properties.

[1]  B. Fischer,et al.  Human express saccades: effects of randomization and daily practice , 2004, Experimental Brain Research.

[2]  P. E. Hallett,et al.  The differentiation of visually guided and anticipatory saccades in gap and overlap paradigms , 2004, Experimental Brain Research.

[3]  B. Fischer,et al.  Saccadic eye movements after extremely short reaction times in the monkey , 1983, Brain Research.

[4]  W. Becker,et al.  An analysis of the saccadic system by means of double step stimuli , 1979, Vision Research.

[5]  John M. Findlay,et al.  Spatial and temporal factors in the predictive generation of saccadic eye movements , 1981, Vision Research.

[6]  R. Wurtz,et al.  Activity of superior colliculus in behaving monkey. 3. Cells discharging before eye movements. , 1972, Journal of neurophysiology.

[7]  J. Droulez,et al.  Some collicular efferent neurons code saccadic eye velocity , 1986, Neuroscience Letters.

[8]  A. J. van Opstal,et al.  Experimental test of two models for the generation of oblique saccades , 2004, Experimental Brain Research.

[9]  P. Schiller,et al.  Single-unit recording and stimulation in superior colliculus of the alert rhesus monkey. , 1972, Journal of neurophysiology.

[10]  D. Sparks,et al.  Dissociation of visual and saccade-related responses in superior colliculus neurons. , 1980, Journal of neurophysiology.

[11]  S. Gielen,et al.  A quantitative analysis of generation of saccadic eye movements by burst neurons. , 1981, Journal of neurophysiology.

[12]  B Fischer,et al.  The preparation of visually guided saccades. , 1987, Reviews of physiology, biochemistry and pharmacology.

[13]  D A Robinson,et al.  Saccades and the quick phase of nystagmus. , 1972, Vision research.

[14]  D. Robinson.  Eye movements evoked by collicular stimulation in the alert monkey. , 1972, Vision research.

[15]  A. J. Van Opstal,et al.  Skewness of saccadic velocity profiles: A unifying parameter for normal and slow saccades , 1987, Vision Research.

[16]  L. Bour,et al.  The Double Magnetic Induction Method for Measuring Eye Movement - Results in Monkey and Man , 1984, IEEE Transactions on Biomedical Engineering.

[17]  D. Sparks.  Functional properties of neurons in the monkey superior colliculus: Coupling of neuronal activity and saccade onset , 1978, Brain Research.

[18]  C. Kennard,et al.  Predictive eye saccades are different from visually triggered saccades , 1987, Vision Research.

[19]  Lawrence Stark,et al.  Predictive Control of Eye Tracking Movements , 1962 .

[20]  P. Dallos,et al.  Learning behavior of the eye fixation control system , 1963 .

[21]  J. E. Lieberman,et al.  Frequency limitations of the two-point central difference differentiation algorithm , 1982, Biological Cybernetics.

[22]  C. Prablanc,et al.  Saccadic responses evoked by presentation of visual and auditory targets , 2004, Experimental Brain Research.

[23]  Bernice W. Polemis.  Nonparametric Statistics for the Behavioral Sciences , 1959 .

[24]  R. Douglas,et al.  Frontal lobe lesions in man cause difficulties in suppressing reflexive glances and in generating goal-directed saccades , 2004, Experimental Brain Research.

[25]  R. Wurtz,et al.  Visual and oculomotor functions of monkey substantia nigra pars reticulata. I. Relation of visual and auditory responses to saccades. , 1983, Journal of neurophysiology.

[26]  R. Wurtz,et al.  Modification of saccadic eye movements by GABA-related substances. I. Effect of muscimol and bicuculline in monkey superior colliculus. , 1985, Journal of neurophysiology.

[27]  J. V. Van Gisbergen,et al.  Skewness of saccadic velocity profiles: a unifying parameter for normal and slow saccades. , 1987, Vision research.

[28]  John H. R. Maunsell,et al.  The effect of frontal eye field and superior colliculus lesions on saccadic latencies in the rhesus monkey. , 1987, Journal of neurophysiology.

[29]  C. Kennard,et al.  Predictive ocular motor control in Parkinson's disease. , 1985, Brain : a journal of neurology.

[30]  J. V. Gisbergen,et al.  A parametric analysis of human saccades in different experimental paradigms , 1987, Vision Research.

[31]  Irene A. Stegun,et al.  Handbook of Mathematical Functions. , 1966 .

[32]  F. A. Miles,et al.  Short-latency ocular following responses of monkey. I. Dependence on temporospatial properties of visual input. , 1986, Journal of neurophysiology.

[33]  A. Fuchs,et al.  Further properties of the human saccadic system: eye movements and correction saccades with and without visual fixation points. , 1969, Vision research.

[34]  C. Bruce,et al.  Primate frontal eye fields. I. Single neurons discharging before saccades. , 1985, Journal of neurophysiology.

[35]  M. Saslow.  Effects of components of displacement-step stimuli upon latency for saccadic eye movement. , 1967, Journal of the Optical Society of America.

[36]  L. Stark,et al.  The main sequence, a tool for studying human eye movements , 1975 .

[37]  L. Rabiner,et al.  An approach to the approximation problem for nonrecursive digital filters , 1970 .

[38]  L. E. Ross,et al.  Children's and adults' predictive saccades to square-wave targets , 1987, Vision Research.