Dead zone for express saccades

SummaryThe saccadic eye movements of three humans and one non-human primate (a male rhesus monkey) have been measured for target eccentricities between 0.3 and 15 deg. With a gap task (fixation point offset precedes target onset by 200 ms) and a target at 4 deg, all subjects produced reasonable amounts of express saccades as indicated by a clear peak in the distribution of their saccadic reaction times (SRT): about 100 ms in human subjects and 70 ms in the monkey. This peak disappeared with decreasing target eccentricity below 2 deg, but saccades of longer (regular) reaction times were still present. Thus it was found that there exists a dead zone for express saccades. In addition, small saccades have a much stronger tendency to overshoot the target and their velocity falls above the main sequence as defined by the least square fit of an exponential v=vo(1-exp(-a/ao)) to the maximal velocity (v) versus amplitude (a) relationship (vo and ao are constants fitted). It is concluded that for small saccades the express way is blocked functionally or does not exist anatomically.

[1]  C. Rashbass,et al.  The relationship between saccadic and smooth tracking eye movements , 1961, The Journal of physiology.

[2]  D Wyman,et al.  The oculomotor error signal in the fovea. , 1972, Vision research.

[3]  R. Steinman,et al.  The smallest voluntary saccade: implications for fixation. , 1973, Vision research.

[4]  D Wyman,et al.  Letter: Latency characteristics of small saccades. , 1973, Vision research.

[5]  D Wyman,et al.  Small step tracking: implications for the oculomotor "dead zone". , 1973, Vision research.

[6]  G. Poggio,et al.  Binocular interaction and depth sensitivity in striate and prestriate cortex of behaving rhesus monkey. , 1977, Journal of neurophysiology.

[7]  Reid Finlayson,et al.  Frontal Lobe Lesions , 1978, Canadian Psychiatric Association journal.

[8]  B. C. Motter,et al.  The functional properties of the light-sensitive neurons of the posterior parietal cortex studied in waking monkeys: foveal sparing and opponent vector organization , 1981, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[9]  D. Bouis,et al.  An accurate and linear infrared oculometer , 1983, Journal of Neuroscience Methods.

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

[11]  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.

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

[13]  A K Moschovakis,et al.  Structure-function relationships in the primate superior colliculus. II. Morphological identity of presaccadic neurons. , 1988, Journal of neurophysiology.

[14]  A K Moschovakis,et al.  Structure-function relationships in the primate superior colliculus. I. Morphological classification of efferent neurons. , 1988, Journal of neurophysiology.

[15]  B. Fischer,et al.  Saccadic Reaction Times of Dyslexic and Age-Matched Normal Subjects , 1990, Perception.

[16]  D Guitton,et al.  Movement of neural activity on the superior colliculus motor map during gaze shifts. , 1991, Science.

[17]  T Mergner,et al.  Saccadic reaction times in patients with frontal and parietal lesions. , 1992, Brain : a journal of neurology.

[18]  Kevin W. Bowyer,et al.  The Functional Properties , 1996 .

[19]  B. Fischer,et al.  Human express saccades: extremely short reaction times of goal directed eye movements , 2004, Experimental Brain Research.

[20]  B. Fischer,et al.  The role of fixation and visual attention in the occurrence of express saccades in man , 2004, European archives of psychiatry and neurological sciences.

[21]  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.

[22]  B. Gaymard,et al.  Cortical control of memory-guided saccades in man , 2004, Experimental Brain Research.