The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
John M Findlay - One of the best experts on this subject based on the ideXlab platform.
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Saccadic Eye Movement programming: sensory and attentional factors
Psychological Research, 2009Co-Authors: John M FindlayAbstract:The relationship between attention and Eye Movements is explored by consideration of the variety of ways attention may affect saccade programming. Four forms of attention are distinguished: one exogenous and three endogenous through either locations or objects or features. Each of these can control or influence the Saccadic generation process. Visual onsets generate a rapid transient signal with low resolution that travels from the visual system to the oculomotor system. Generation of an Eye Movement is associated with an attentional signal, probably also with low resolution, travelling from the oculomotor system to the visual system. A high-resolution attentional signal, which appears to require voluntary effort, can also select Saccadic targets.
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Saccadic Eye Movement programming in unilateral neglect
Neuropsychologia, 1996Co-Authors: Robin Walker, John M FindlayAbstract:Abstract The present study examined the Eye Movements made by patients with unilateral neglect under fixation gap and overlap conditions. The prior offset of fixation in a + 100 msec gap condition did not produce an increase in the numbers of contralesional saccades made by 3 out of 4 patients. This finding is incompatible with the view that the deficit in producing contralesional saccades reflects an inability to disengage visual attention from fixation. A significant reduction in saccade latency was, however, obtained in the gap condition (‘gap effect’). The latency reduction in the gap condition is consistent with models which attribute the gap effect to warning signal effects and the release of an ocular rather than an attentional disengagement mechanism. Saccade latency was not increased when two targets were presented bilaterally and simultaneously in both hemifields (in contrast to the increase in latency shown by normal subjects). The lack of a normal ‘bilateral target effect’ in neglect is attributed to an imbalance in the level of activity in the Saccadic system. Three patients showed visual ‘extinction’ and did not make saccades to the contralesional bilateral targets. In contrast R.R. who shows object-based neglect did not show extinction and made saccades to the contralesional bilateral targets. This suggests that visual extinction may be influenced by the form of neglect shown by the patient. The effects on saccade amplitude of presenting two targets in the same hemifield were also examined in a global effect task. One patient showed a much greater global effect than normal when pairs of targets were presented in his ipsilesional hemifield. In contrast R.R. showed a normal magnitude global effect. It appears that the form of neglect shown by a patient is a factor that influences their Eye Movement behaviour on simple saccade tasks and these Eye Movement abnormalities cannot be accounted for by a deficit of attentional disengagement.
Haruyuki Minamitani - One of the best experts on this subject based on the ideXlab platform.
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Dynamics of Saccadic Eye Movement depending on diurnal variation in human alertness
Systems and Computers in Japan, 2002Co-Authors: Akinori Ueno, Tsuyoshi Tateyama, Moriichiro Takase, Haruyuki MinamitaniAbstract:From the viewpoint of traffic accident prevention or intelligent interface construction, the proposal of indices which can simply evaluate alertness is desirable. In this paper, to investigate the possibility of alertness evaluation using Saccadic Eye Movement (SC), we report 24-hour sleep deprivation experiments and investigate the relationship between the diurnal variation and SC dynamics. It has become clear that three parameters of SC, namely, the peak velocity/duration ratio, the normalized peak velocity, and the normalized duration, have strong correlations with the amplitude component of brain waves, sleepiness, and subjective alertness. These results imply that SC dynamics have a high dependence on the two alertness indices, physiological and subjective, and the possibility of application of the SC dynamics to alertness evaluation is shown. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(7): 95–103, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1145
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Parametric analysis of Saccadic Eye Movement depending on vigilance states
Proceedings of 18th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 1996Co-Authors: A Ueno, M Takase, Haruyuki MinamitaniAbstract:The purpose of this study was to investigate the relationship between characteristic of Saccadic Eye Movement and vigilance state. The authors survEyed this by comparing the waveform parameter of Saccadic velocity to EEG parameter obtained from spectral power of /spl alpha/ and /spl beta/ wave band or to subjective vigilance states and sleepness. The authors' result showed that the shapes of Saccadic velocity became blunt according to a decline in the vigilance state and also to a increase in sleepiness. This indicated the possibility for estimation of vigilance states by using characteristics of Saccadic Eye Movement.
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Relationship between vigilance levels and characteristics of Saccadic Eye Movement
Proceedings of 17th International Conference of the Engineering in Medicine and Biology Society, 1995Co-Authors: A Ueno, M Takase, Haruyuki MinamitaniAbstract:The purpose of this study was to investigate the possibility for evaluating vigilance levels using a parameter of Saccadic Eye Movement. EEG was measured and analyzed by means of fast Fourier transform, and the spectral power of /spl alpha/ and /spl beta/ wave bands were obtained so as to extract [/spl beta/]/[/spl alpha/+/spl beta/] which was assumed to reflect vigilance levels. Eye Movement was measured so as to calculate Saccadic peak velocity (SPV) and relative SPV (RSPV) which was normalized by the mean SPV at the corresponding amplitude of saccade. The relationship between [/spl beta/]/[/spl alpha/+/spl beta/] and RSPV was investigated and it revealed that RSPV decreased according to the decline in the vigilance level. This indicates the possibility for evaluating vigilance levels using RSPV.
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Adaptive Process Of Visually Triggered Saccadic Eye Movement
[1990] Proceedings of the Twelfth Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 1Co-Authors: M. Ohmori, T. Inagaki, Y. Takahashi, Yoshinobu Ebisawa, Haruyuki MinamitaniAbstract:Adaptive process of visually triggered saccade has been investigated. Two types of the double target step methods which are developed so as to remove the re-adaptation are used. The one is SDexperiment to increase Saccadic gain, while the other is ODexperiment to decrease it. Gain adaptation of the saccade differs within the direction of Eye Movement. Also the adaptation has different time courses for SD and OD states. Furthermore, the change of gain for the adapted Eye has influences on the gain for the non-adapted Eye. As a result, adaptive process of visually triggered saccade is parametric.
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Parametric and amplitude-specific gain adaptability of Saccadic Eye Movement
Images of the Twenty-First Century. Proceedings of the Annual International Engineering in Medicine and Biology Society, 1Co-Authors: M. Ohmori, T. Inagaki, Yoshinobu Ebisawa, Haruyuki MinamitaniAbstract:Properties of adaptation in the human visually triggered Saccadic system are studied. A previously published double step experimental method is improved to remove the redundant adaptation process. The difference of adaptation in the direction of Eye Movement, the effect of recovering the inherent condition during rest of the double step adaptation experiments, and the effect of repetition of the experiments are presented. The parametric adaptability is discussed by comparing the present study other experimental methods and results. It is concluded that the amplitude-specific adaptability of the Saccadic Eye Movement is parametric. >
Edward J. Tehovnik - One of the best experts on this subject based on the ideXlab platform.
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Conditions that alter Saccadic Eye Movement latencies and affect target choice to visual stimuli and to electrical stimulation of area V1 in the monkey.
Visual neuroscience, 2008Co-Authors: Peter H. Schiller, Geoffrey L. Kendall, Warren M. Slocum, Edward J. TehovnikAbstract:In this study, we examined procedures that alter Saccadic latencies and target selection to visual stimuli and electrical stimulation of area V1 in the monkey. It has been shown that Saccadic Eye Movement latencies to singly presented visual targets form a bimodal distribution when the fixation spot is turned off a number of milliseconds prior to the appearance of the target (the gap period); the first mode has been termed express saccades and the second regular saccades. When the termination of the fixation spot is coincident with the appearance of the target (0 ms gap), express saccades are rarely generated. We show here that a bimodal distribution of Saccadic latencies can also be obtained when an array of visual stimuli is presented prior to the appearance of the visual target, provided the elements of the array overlap spatially with the visual target. The overall latency of the Saccadic Eye Movements elicited by electrical stimulation of area V1 is significantly shortened both when a gap is introduced between the termination of the fixation spot and the stimulation and when an array is presented. However, under these conditions, the distribution of Saccadic latencies is unimodal. When two visual targets are presented after the fixation spot, introducing a gap has no effect on which target is chosen. By contrast, when electrical stimulation is paired with a visual target, introducing a gap greatly increases the frequency with which the electrical stimulation site is chosen.
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Phosphene Induction and the Generation of Saccadic Eye Movements by Striate Cortex
Journal of neurophysiology, 2004Co-Authors: Edward J. Tehovnik, Warren M. Slocum, Christina E. Carvey, Peter H. SchillerAbstract:The purpose of this review is to critically examine phosphene induction and Saccadic Eye Movement generation by electrical microstimulation of striate cortex (area V1) in humans and monkeys. The fo...
Matthew W Mosconi - One of the best experts on this subject based on the ideXlab platform.
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Saccadic Eye Movement abnormalities in autism spectrum disorder indicate dysfunctions in cerebellum and brainstem
Molecular Autism, 2014Co-Authors: Lauren M Schmitt, Edwin H Cook, John A Sweeney, Matthew W MosconiAbstract:Individuals with autism spectrum disorder (ASD) show atypical scan paths during social interaction and when viewing faces, and recent evidence suggests that they also show abnormal Saccadic Eye Movement dynamics and accuracy when viewing less complex and non-social stimuli. Eye Movements are a uniquely promising target for studies of ASD as their spatial and temporal characteristics can be measured precisely and the brain circuits supporting them are well-defined. Control of saccade metrics is supported by discrete circuits within the cerebellum and brainstem - two brain regions implicated in magnetic resonance (MR) morphometry and histopathological studies of ASD. The functional integrity of these distinct brain systems can be examined by evaluating different parameters of visually-guided saccades. A total of 65 participants with ASD and 43 healthy controls, matched on age (between 6 and 44-years-old), gender and nonverbal IQ made saccades to peripheral targets. To examine the influence of attentional processes, blocked gap and overlap trials were presented. We examined saccade latency, accuracy and dynamics, as well as the trial-to-trial variability of participants’ performance. Saccades of individuals with ASD were characterized by reduced accuracy, elevated variability in accuracy across trials, and reduced peak velocity and prolonged duration. In addition, their saccades took longer to accelerate to peak velocity, with no alteration in the duration of saccade deceleration. Gap/overlap effects on saccade latencies were similar across groups, suggesting that visual orienting and attention systems are relatively spared in ASD. Age-related changes did not differ across groups. Deficits precisely and consistently directing Eye Movements suggest impairment in the error-reducing function of the cerebellum in ASD. Atypical increases in the duration of Movement acceleration combined with lower peak saccade velocities implicate pontine nuclei, specifically suggesting reduced excitatory activity in burst cells that drive saccades relative to inhibitory activity in omnipause cells that maintain stable fixation. Thus, our findings suggest that both cerebellar and brainstem abnormalities contribute to altered sensorimotor control in ASD.
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Saccadic Eye Movement abnormalities in autism spectrum disorder indicate dysfunctions in cerebellum and brainstem
Molecular Autism, 2014Co-Authors: Laure M Schmi, Edwin H Cook, John A Sweeney, Matthew W MosconiAbstract:Individuals with autism spectrum disorder (ASD) show atypical scan paths during social interaction and when viewing faces, and recent evidence suggests that they also show abnormal Saccadic Eye Movement dynamics and accuracy when viewing less complex and non-social stimuli. Eye Movements are a uniquely promising target for studies of ASD as their spatial and temporal characteristics can be measured precisely and the brain circuits supporting them are well-defined. Control of saccade metrics is supported by discrete circuits within the cerebellum and brainstem - two brain regions implicated in magnetic resonance (MR) morphometry and histopathological studies of ASD. The functional integrity of these distinct brain systems can be examined by evaluating different parameters of visually-guided saccades. A total of 65 participants with ASD and 43 healthy controls, matched on age (between 6 and 44-years-old), gender and nonverbal IQ made saccades to peripheral targets. To examine the influence of attentional processes, blocked gap and overlap trials were presented. We examined saccade latency, accuracy and dynamics, as well as the trial-to-trial variability of participants’ performance. Saccades of individuals with ASD were characterized by reduced accuracy, elevated variability in accuracy across trials, and reduced peak velocity and prolonged duration. In addition, their saccades took longer to accelerate to peak velocity, with no alteration in the duration of saccade deceleration. Gap/overlap effects on saccade latencies were similar across groups, suggesting that visual orienting and attention systems are relatively spared in ASD. Age-related changes did not differ across groups. Deficits precisely and consistently directing Eye Movements suggest impairment in the error-reducing function of the cerebellum in ASD. Atypical increases in the duration of Movement acceleration combined with lower peak saccade velocities implicate pontine nuclei, specifically suggesting reduced excitatory activity in burst cells that drive saccades relative to inhibitory activity in omnipause cells that maintain stable fixation. Thus, our findings suggest that both cerebellar and brainstem abnormalities contribute to altered sensorimotor control in ASD.
J. C. Lynch - One of the best experts on this subject based on the ideXlab platform.
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Functionally defined smooth and Saccadic Eye Movement subregions in the frontal Eye field of Cebus monkeys
Journal of Neurophysiology, 1996Co-Authors: Jun-ru Tian, J. C. LynchAbstract:1. Intracortical microstimulation was used to localize and define the smooth and Saccadic Eye Movement subregions of the frontal Eye field (FEF) and the supplementary Eye field (SEF) in nine hemisp...
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Corticocortical input to the smooth and Saccadic Eye Movement subregions of the frontal Eye field in Cebus monkeys
Journal of neurophysiology, 1996Co-Authors: Jun-ru Tian, J. C. LynchAbstract:1. The locations and connections of the smooth and Saccadic Eye Movement subregions of the frontal Eye field (FEFsem and FEFsac, respectively) were investigated in seven hemispheres of five Cebus m...
