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Topic: Saccades

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	Saccade - Wikipedia, the free encyclopedia
		One reason for saccades of the human eye is that only the central part of the retina, the fovea, has a high concentration of color sensitive photoreceptor cells called cone cells.
		In saccades larger than 60 degrees, the peak velocity remains constant at the maximum velocity attainable by the eye.
		This phenomenon, known as saccadic masking or saccadic suppression, is known to occur in the time preceding a saccadic eye movement, suggesting that there are neurological functions at work rather than simple mechanical or optical functions, such as retinal blur.
	en.wikipedia.org /wiki/Saccade (840 words)

	SACCADE TESTS
		Saccadic velocity cannot be altered voluntarily and is not affected substantially by age or gender.
		Saccadic latencies are calculated from the difference in time between target displacement and the onset of the first saccade towards the new target position.
		Normal saccadic latencies are independent of target amplitude and are insensitive to the method used to record eye movements, but vary according to target luminance, size, contrast, whether the target is visual, auditory or both, and the predictability of the target (Leigh and Zee, 1991).
	www.dizziness-and-balance.com /practice/saccade.htm (4202 words)

	Roger Carpenter's Eye Movements Page
		Of course, in real life there are many objects in the world around us that might be targets for saccades, so in addition to neural machinery in the brainstem to get the eye on to a designated target, we also need mechanisms higher up for choosing what target to look at in the first place.
		Some of this selection seems to be done in the frontal part of the cerebral cortex, where there are units whose firing seems to reflect the processes of choosing and discriminating between targets.
		Work on saccadic reaction times in humans seems to suggest that the brain runs a kind of race between signals representing different possible targets, with more probable targets starting nearer the finishing post than less probable ones.
	www.cai.cam.ac.uk /people/rhsc/oculo.html (879 words)

	SACCADE TESTS
		Disorders which affect vertical saccades to a greater extent than horizontal saccades include disorders of the midbrain, such as progressive supranuclear palsy (PSP), and the ocular muscle involvement typical of thyroid disease.
		One cause is the opsoclonus syndrome or it's relative, ocular flutter.
		(1986) Contrapulsion of saccades and ipsilateral ataxia: A unilateral disorder of the rostral cerebellum.
	www.tchain.com /otoneurology/practice/saccade.htm (3882 words)

	Journal of Vision - Express saccades: the conditions under which they are realized and the brain structures involved, ...
		What is learned is the vector of the saccade to be produced, not the location of the target is space or the orbital position of the eye.
		Express saccades are made with high frequency to the second of two successive targets as long as the vector is one that has been learned.
		But superior colliculus lesions eliminate express saccades; no recovery is evident It appears therefore that the cortical areas involved in express saccade generation send their signals to the brainstem through the superior colliculus.
	journalofvision.org /2/7/174 (374 words)

	Journal of Vision - Attentional enhancement along the path of a sequence of saccades, by Gersch, Schnitzer, Sanghvi, ...
		Dual-task studies have demonstrated superior perceptual performance at the saccadic goal, implying that a single attentional filter is used by saccades and perception (e.g., Gersch et al., 2004).
		To address the conflict between the immediate demands of saccades and the larger needs of vision, we examined the distribution of attention during saccadic sequences.
		Perceptual performance was enhanced at the goal of the upcoming saccade (as expected), but enhancement was also observed elsewhere along the saccadic path (the target of future saccades, and previously-visited locations).
	www.journalofvision.org /6/6/89 (378 words)

	The Saccades of the oculomotor system in vision
		The minor saccades can also be subdivided into the minisaccades (or flicks) that are generally between 2 minutes of arc (0.033 degrees) and 1.2 degrees in amplitude and the even smaller microsaccades with a typical amplitude of 40 seconds of arc (0.01 degrees).
		Large saccades occur relatively infrequently (typically in the 3-20 second range)and are frequently associated with changing the orientation of the head and body.
		The minor saccadic motions of the eyes, microsaccades and minisaccades (flicks), are the key to the ability of the visual system to perceive and interprete images.
	www.4colorvision.com /reading/saccades.htm (1342 words)

	Express Saccades (Site not responding. Last check: 2007-09-10)
		Express saccades are a visually guided saccades that constitute an early mode (peak) around 70-80 ms in the monkey and around 100 ms in man in bi- or even trimodal distribution of saccadic reaction times.
		Express saccades occur also as erratic saccades (prosaccades to the stimulus) in the antisaccade task.
		Express saccades occur often as erratic prosaccades in an antisaccade task.
	www.optomotorik.de /blicken/express.htm (183 words)

	Comparison of the main sequence of reflexive saccades and the quick phases of optokinetic nystagmus -- Garbutt et al. ...
		It is impossible to voluntarily alter the velocity of a saccade
		The duration of saccades and OKN quick phases differed slightly, but were not statistically different (see Table 1, Fig 2A).
		Figure 2 Scatter plot of the saccadic and OKN quick phase main sequences for duration (A) and for peak velocity (B) for a typical subject (subject 9).
	bjo.bmj.com /cgi/content/full/85/12/1477 (3613 words)

	Saccades (Site not responding. Last check: 2007-09-10)
		Saccades are frequent rapid long-latency voluntary ballistic conjugate accurate foveating eye movements.
		You make saccades about 3 times per second; they can be voluntarily suppressed during such activities as aiming a gun or threading a needle.
		saccade to the target, in spite of the fact that the retinal error was purely vertical.
	www.engin.brown.edu /courses/en122/Lcturs/sacc05.html (1473 words)

	Control of volitional and reflexive saccades in Tourette's syndrome -- LeVasseur et al. 124 (10): 2045 -- Brain
		In the delayed saccade task, SRT was measured from FP disappearance to the onset of the eye movement.
		saccades that were between 18 and 21° in amplitude.
		Saccades in Huntington's disease: predictive tracking and interaction between release of fixation and initiation of saccades.
	brain.oxfordjournals.org /cgi/content/full/124/10/2045 (6648 words)

	Neuronal Correlates for Preparatory Set Associated with Pro-Saccades and Anti-Saccades in the Primate Frontal Eye Field ...
		A, Mean correlation coefficients between neuronal activity and saccadic reaction times in 10 msec bins from 200 msec before to 100 msec after stimulus presentation for pro-saccades (thick lines) and anti-saccades (thin lines) in the response field of the neuron (solid lines) and to opposite position (dashed lines).
		C, The saccade activity (A, shaded area) of individual neurons on express saccade trials (mean, 97.1 ± 16.9 spikes/sec) is plotted against the saccade activity on regular saccade trials (mean, 98.2 ± 19.4 spikes/sec).
		C, The saccade activity (A, shaded area) of individual neurons on pro-saccade trials is plotted against the saccade activity on anti-saccade trials.
	www.jneurosci.org /cgi/content/full/20/1/387 (8051 words)

	Effects of TMS over the Right Prefrontal Cortex on Latency of Saccades and Convergence -- Coubard et al. 44 (2): 600 -- ...
		of fixation, thereby facilitating the onset of the saccade.
		The target LED could be (1) one of the two lateral LEDs at 150 cm (pure saccade); (2) the center at 20 cm (pure convergence); or (3) one of the two lateral LEDs at 20 cm (combined movement).
		For pure saccades, results are presented in Figure 3.
	www.iovs.org /cgi/content/full/44/2/600 (5036 words)

	The Planning and Guiding of Reading Saccades: a Repetitive Transcranial Magnetic Stimulation Study -- Leff et al. 11 ...
		A cross is presented to the left of the screen for the duration of the interstimulus interval (4 s), and the subjects are instructed to fixate on this.
		Muri R, Rosler K, Hess C (1994) Influence of transcranial magnetic stimulation on the execution of memorised sequences of saccades in man. Exp Brain Res 101:521–524.
		Oyachi H, Ohtsuka K (1995) Transcranial magnetic stimulation of the posterior parietal cortex degrades accuracy of memory-guided saccades in humans.
	cercor.oxfordjournals.org /cgi/content/full/11/10/918 (4649 words)

	Binocular Coordination of Saccades in Children with Strabismus before and after Surgery -- Bucci et al. 43 (4): 1040 -- ...
		Individual average disconjugacy of saccades (A), of the conjugate (B) and disconjugate (C) component of postsaccadic eye drift expressed as a ratio to the amplitude of the saccade; values are shown for each subject before (empty bars) and after (fl bars) surgery; the letter X indicates divergent strabismus.
		Means are based on 40 to 69 saccades before surgery and on 35 to 71 saccades after surgery.
		amplitude of saccades for the dominant and for the nondominant
	www.iovs.org /cgi/content/full/43/4/1040 (4446 words)

	Effects of lesions of the human posterior thalamus on ocular fixation during voluntary and visually triggered saccades ... (Site not responding. Last check: 2007-09-10)
		Effects of lesions of the human posterior thalamus on ocular fixation during voluntary and visually triggered saccades -- Rafal et al.
		Saccade latency was measured with an Eye Trac 210 scleral reflectance
		Saccadic eye movements following kainic acid lesions of the pulvinar in monkeys.
	jnnp.bmjjournals.com /cgi/content/full/75/11/1602 (3039 words)

	Effects of Ketamine on Leading Saccades During Smooth-Pursuit Eye Movements May Implicate Cerebellar Dysfunction in ...
		saccadic eye movements is related to schizophrenia vulnerability.
		These values were not significantly different for the ratio of leading saccades to pursuit response time (F=0.67, df=1, 36, p>0.05) or for the ratio of leading to total saccade time (F=0.77, df=1, 36, p>0.05).
		The baseline values for the first-degree relatives were significantly higher than the baseline values of the normal subjects for the ratio of leading saccades to pursuit response time (F=5.45, df=1, 36, p<0.05) and for the ratio of leading to total saccade time (F=5.06, df=1, 36, p<0.05).
	ajp.psychiatryonline.org /cgi/content/full/159/9/1490 (3914 words)

	Primate Superior Colliculus
		* Recent muscimol (a GABA agonist) studies that the superior colliculus is involved in calculation of saccade amplitude and direction.
		Foveation Hypothesis - The foveation hypothesis states that the role of the superior colliculus is to code the location of a visual target relative to the fovea and to intitiate a saccade that will produce foveal acquisition of the target.
		The hypothesis is that the superior colliculus codes for saccades in motor-error coordinates (position of eyes in the orbit relative to the target position), i.e.
	www.keck.ucsf.edu /~sabes/Cortex/SC.htm (1082 words)

	Pathophysiology of slow vertical saccades in progressive supranuclear palsy -- Bhidayasiri et al. 57 (11): 2070 -- ...
		Pathophysiology of slow vertical saccades in progressive supranuclear palsy -- Bhidayasiri et al.
		Pathophysiology of slow vertical saccades in progressive supranuclear palsy
		Vertical saccades were slowed more than horizontal saccades
	www.neurology.org /cgi/content/abstract/57/11/2070 (528 words)

	Evaluating Large Saccades in Patients with Brain-Stem or Cerebellar Disorders -- KUMAR et al. 1039 (1): 404 -- Annals ...
		Evaluating Large Saccades in Patients with Brain-Stem or Cerebellar Disorders -- KUMAR et al.
		waveform of large saccades, it is possible to examine more closely
		of saccades occur; such velocity waveforms cannot be modeled
	www.annalsnyas.org /cgi/content/abstract/1039/1/404 (335 words)

	International Society of Presbyopia - Links - Saccades (Site not responding. Last check: 2007-09-10)
		International Society of Presbyopia - Links - Saccades
		We subscribe to the HONcode principles of the
		NCM 2001 Poster Abstract - The Nature of Variability in Saccades
	www.wophth.com /w_ophth/physiol/ph_15.htm (166 words)

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