TEMPORAL ANALYSIS OF THE ACCELERATION AND DECELERATION PHASES FOR VISUAL SACCADES

Previous studies showed that the relation for product of peak velocity and duration against saccadic amplitude was highly linear correlated. The velocity profile was related as a triangular profile and referred to the saccadic amplitude as an integration of the profile, so that the amplitude is proportional to the product of peak velocity and duration. The saccadic amplitude can be described as a function of peak velocity and duration. In this study, in addition to the triangular profile, the rational power function was applied to explain the above linear relation. The acceleration and deceleration phases can be described, respectively, with the different shape parameters (n1 and n2). Finally, we described the product of peak velocity and acceleration time relating to the acceleration amplitude, and the product of peak velocity and deceleration time relating to the deceleration amplitude. The results show that the acceleration and deceleration phase parameters could be used to accurately delineate the saccadic characteristics.

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Evidence That the Superior Colliculus Participates in the Feedback Control of Saccadic Eye Movements

Journal of Neurophysiology ◽

10.1152/jn.00886.2000 ◽

2002 ◽

Vol 87 (2) ◽

pp. 679-695 ◽

Cited By ~ 91

Author(s):

Robijanto Soetedjo ◽

Chris R. S. Kaneko ◽

Albert F. Fuchs

Keyword(s):

Superior Colliculus ◽

Firing Rate ◽

Saccadic Eye Movements ◽

Burst Duration ◽

Saccadic Amplitude ◽

Optimal Vector ◽

Deceleration Phase ◽

Acceleration And Deceleration ◽

Motor Error ◽

Saccade Duration

There is general agreement that saccades are guided to their targets by means of a motor error signal, which is produced by a local feedback circuit that calculates the difference between desired saccadic amplitude and an internal copy of actual saccadic amplitude. Although the superior colliculus (SC) is thought to provide the desired saccadic amplitude signal, it is unclear whether the SC resides in the feedback loop. To test this possibility, we injected muscimol into the brain stem region containing omnipause neurons (OPNs) to slow saccades and then determined whether the firing of neurons at different sites in the SC was altered. In 14 experiments, we produced saccadic slowing while simultaneously recording the activity of a single SC neuron. Eleven of the 14 neurons were saccade-related burst neurons (SRBNs), which discharged their most vigorous burst for saccades with an optimal amplitude and direction (optimal vector). The optimal directions for the 11 SRBNs ranged from nearly horizontal to nearly vertical, with optimal amplitudes between 4 and 17°. Although muscimol injections into the OPN region produced little change in the optimal vector, they did increase mean saccade duration by 25 to 192.8% and decrease mean saccade peak velocity by 20.5 to 69.8%. For optimal vector saccades, both the acceleration and deceleration phases increased in duration. However, during 10 of 14 experiments, the duration of deceleration increased as fast as or faster than that of acceleration as saccade duration increased, indicating that most of the increase in duration occurred during the deceleration phase. SRBNs in the SC changed their burst duration and firing rate concomitantly with changes in saccadic duration and velocity, respectively. All SRBNs showed a robust increase in burst duration as saccadic duration increased. Five of 11 SRBNs also exhibited a decrease in burst peak firing rate as saccadic velocity decreased. On average across the neurons, the number of spikes in the burst was constant. There was no consistent change in the discharge of the three SC neurons that did not exhibit bursts with saccades. Our data show that the SC receives feedback from downstream saccade-related neurons about the ongoing saccades. However, the changes in SC firing produced in our study do not suggest that the feedback is involved with producing motor error. Instead, the feedback seems to be involved with regulating the duration of the discharge of SRBNs so that the desired saccadic amplitude signal remains present throughout the saccade.

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THE PEAK VELOCITY AND SKEWNESS RELATIONSHIP FOR THE REFLEXIVE SACCADES

Biomedical Engineering Applications Basis and Communications ◽

10.4015/s1016237202000115 ◽

2002 ◽

Vol 14 (02) ◽

pp. 71-80 ◽

Cited By ~ 2

Author(s):

YUNG-FU CHEN ◽

HSUAN-HUNG LIN ◽

TAINSONG CHEN ◽

TZU-TUNG TSAI ◽

I-FEN SHEE

Keyword(s):

Peak Velocity ◽

Normal Subjects ◽

Saccadic Amplitude ◽

Wide Range ◽

Acceleration And Deceleration ◽

History Of ◽

Saccadic Velocity ◽

Highly Correlated ◽

The Relationship ◽

Reflexive Saccades

The main sequence relations of saccades stated that the duration was linearly correlated to the saccadic amplitude for a wide range, whereas the peak velocity correlated exponentially to the amplitude with saturation occurred at 30°-40°. Skewness was used efficiently in delineating the asymmetry between the acceleration and deceleration phases of the saccadic velocity profiles. It can be estimated from the shape parameter obtained by applying gamma function to the velocity profile. The relationship between peak velocity and skewness was derived according to the following observations. (1) At the same target amplitude and under the similar test conditions, data from previous investigations showed that great intra- and inter-subject variation of the peak velocity and the skewness were always observed. (2) Although the velocity was substantially decreased and the duration greatly increased, accuracy was not affected with the saccadic amplitude was almost unchanged for the subjects after diazepam had been taken. (3) The duration of acceleration phase is almost unchanged for different amplitudes. Fifteen normal subjects (range 21 to 26 years with mean of 23.6) without history of neurological disease were recruited and tested in this study. Electro-oculograph (EOG) was used for recording the eye movements with amplitudes ranging from 10° to 60°. The results show that the data were highly correlated to the derived peak velocity and skewness relation with correlation coefficient (R) as high as 0.66-0.92 for great amplitudes (>30°). This study provides an alternative method in quantitative analysis of saccadic dynamics

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Abstract 2281: Mitral E Wave Deceleration Time to Peak E Velocity Ratio And Cardiovascular Outcome in Hypertensive Patients During Anti-Hypertensive Treatment: the LIFE Echo-Substudy.

Circulation ◽

10.1161/circ.116.suppl_16.ii_498 ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Marcello Chinali ◽

Rakesh K Mishra ◽

Giovanni de Simone ◽

Gerard P Aurigemma ◽

Eva Gerdts ◽

...

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Cox Regression ◽

Peak Velocity ◽

Cox Model ◽

Velocity Ratio ◽

Univariate Analysis ◽

Positive Association ◽

Hypertensive Patients ◽

Deceleration Time

Background: Early mitral flow deceleration time (DTE) is a prognostically validated marker of LV chamber stiffness. However, for any given LV stiffness, a higher E peak velocity (E) is associated with longer DTE, suggesting that the prognostic relevance of DTE might be influenced by variations in cardiac preload (e.g. during anti-hypertensive treatment). It is not known whether normalization of deceleration time for E-velocity (DTE/E) might be a more stable diastolic index for prediction of incident cardiovascular (CV) events in hypertensive patients during treatment, as compared to DTE. Methods: We evaluated 770 hypertensive patients (66±7 years; 42% women) with ECG-LV hypertrophy enrolled in the LIFE echo-substudy. Echocardiographic exams were performed annually for 5 years during anti-hypertensive treatment. Prognostic value of basal DTE/E was preliminary evaluated. Variation over time of both DTE/E and DTE were therefore analyzed in relation to incident combined fatal and non-fatal CV events. Results: During follow-up, 69 CV events occurred (9% of study population). Mean basal DTE/pE was 3.55±1.55 sec 2 /cm*10 −3. In univariate analysis baseline DTE/E was associated positively with age (r=0.10; p<0.01), relative wall thickness (r=0.13; p<0.01) and isovolumic relaxation time (r=0.26; p<0.001) and negatively with heart rate (r=−0.20; p<0.001); no association was found with systolic blood pressure, diastolic blood pressure, LV mass or ejection fraction. Unadjusted Cox regression showed a positive association between baseline DTE/E and CV events [(HR=1.21 (95%CI= 1.07–1.37); p=0.002]. In time-varying Cox model, independently of age, gender, type of anti-hypertensive treatment and in-treatment heart rate, higher in-treatment DTE/E was associated with higher rate of CV events [(HR=1.26 (95%CI= 1.04 –1.80); p<0.026], whereas no association was found for in-treatment DTE (p=NS). Conclusions: In a population of treated hypertensive patients with ECG-LV hypertrophy, the ratio of in-treatment DTE/E, but not DTE alone, independently predicts incident CV events. In high-risk hypertensive patients, normalization of DTE for E peak velocity might be preferred to DTE in evaluating diastolic function during anti-hypertensive treatment.

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Continuous-scan capability at SSRL and applications to X-ray diffraction

Journal of Synchrotron Radiation ◽

10.1107/s1600577516008225 ◽

2016 ◽

Vol 23 (4) ◽

pp. 909-918 ◽

Cited By ~ 2

Author(s):

Chunlei Li ◽

Andrew M. Kiss ◽

Douglas G. Van Campen ◽

Alex Garachtchenko ◽

Yuriy Kolotovsky ◽

...

Keyword(s):

Signal To Noise Ratio ◽

X Ray Diffraction ◽

Scanning Method ◽

X Ray ◽

Motor Controller ◽

Acceleration And Deceleration ◽

Data Points ◽

Total Measurement Time ◽

Zno Powder ◽

Deceleration Time

Typical X-ray diffraction measurements are made by moving a detector to discrete positions in space and then measuring the signal at each stationary position. This step-scanning method can be time-consuming, and may induce vibrations in the measurement system when the motors are accelerated and decelerated at each position. Furthermore, diffraction information between the data points may be missed unless a fine step-scanning is used, which further increases the total measurement time. To utilize beam time efficiently, the motor acceleration and deceleration time should be minimized, and the signal-to-noise ratio should be maximized. To accomplish this, an integrated continuous-scan system was developed at the Stanford Synchrotron Radiation Lightsource (SSRL). The continuous-scan system uses an in-house integrated motor controller system and counter/timer electronics.SPECsoftware is used to control both the hardware and data acquisition systems. The time efficiency and repeatability of the continuous-scan system were tested using X-ray diffraction from a ZnO powder and compared with the step-scan technique. Advantages and limitations of the continuous-scan system and a demonstration of variable-velocity continuous scan are discussed.

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Evaluation of the Acceleration and Deceleration Phase-Rectified Slope to Detect and Improve IUGR Clinical Management

Computational and Mathematical Methods in Medicine ◽

10.1155/2015/236896 ◽

2015 ◽

Vol 2015 ◽

pp. 1-9 ◽

Cited By ~ 7

Author(s):

Salvatore Tagliaferri ◽

Andrea Fanelli ◽

Giuseppina Esposito ◽

Francesca Giovanna Esposito ◽

Giovanni Magenes ◽

...

Keyword(s):

Intrauterine Growth Restriction ◽

High Performance ◽

Neonatal Outcome ◽

Pearson Correlation ◽

Roc Curves ◽

Deceleration Phase ◽

Pearson Correlation Test ◽

Acceleration And Deceleration ◽

Gestational Week ◽

Standard Linear

Objective.This study used a new method called Acceleration (or Deceleration) Phase-Rectified Slope, APRS (or DPRS) to analyze computerized Cardiotocographic (cCTG) traces in intrauterine growth restriction (IUGR), in order to calculate acceleration- and deceleration-related fluctuations of the fetal heart rate, and to enhance the prediction of neonatal outcome.Method.Cardiotocograms from a population of 59 healthy and 61 IUGR fetuses from the 30th gestation week matched for gestational age were included. APRS and DPRS analysis was compared to the standard linear and nonlinear cCTG parameters. Statistical analysis was performed through thet-test, ANOVA test, Pearson correlation test and receiver operator characteristic (ROC) curves (p<0,05).Results.APRS and DPRS showed high performance to discriminate between Healthy and IUGR fetuses, according to gestational week. A linear correlation with the fetal pH at birth was found in IUGR. The area under the ROC curve was 0.865 for APRS and 0.900 for DPRS before the 34th gestation week.Conclusions.APRS and DPRS could be useful in the identification and management of IUGR fetuses and in the prediction of the neonatal outcome, especially before the 34th week of gestation.

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An Ascending Aortic Haemodynamic Comparison Between Normotensive and Hypertensive Subjects

International Journal of Medical and Dental Sciences ◽

10.18311/ijmds/2013/19816 ◽

2018 ◽

Vol 2 (1) ◽

pp. 16

Author(s):

Vijay Kumar Narayana ◽

Rajeev Sharma ◽

Niranjan Murthy

Keyword(s):

Blood Pressure ◽

Blood Flow ◽

Ejection Fraction ◽

Pressure Gradient ◽

Aortic Blood Flow ◽

Ejection Time ◽

Acceleration Time ◽

Aortic Blood ◽

Ascending Aortic Diameter ◽

Deceleration Time

Background: Systemic hypertension, a common disorder with potentially serious complications, exerts ill effects through structural and functional modifications of arterial wall. Haemodynamics play an important role in the development of atherosclerosis. Local hemodynamic temporal pressure and wall shear stress are important for understanding the mechanisms leading to various complications in cardiovascular function.Objectives: Since we could not find such a study in literature involving Indian population, this prompted us to investigate and establish the relationship between the blood pressure and the ascending aortic pulse wave parameters in normal individuals and compare the same with hypertensives.Material and Methods: A case control study was done in a tertiary care hospital involving 25 hypertensive parents and further compared with 25 normotensive subjects of same age group acting as control. The GE ̶ P 100 Doppler echocardiography machine was used to study acceleration time, deceleration time, ejection time, ejection fraction, peak flow velocity and pressure gradient in hypertensives and compared the same with age matched normotensive. Also ascending aortic diameter was mapped at the annulus.Results: The results of our study confirmed our assumption that in hypertensive the ascending aortic haemodynamic parameters are abnormal and both systolic and diastolic blood pressure does exert a statistically significant influence on the Doppler parameters of ascending aorta. The acceleration time, deceleration time, pressure gradient and ejection time showed statistically significant increase in hypertensives when compared to normotensive. At the same time the ejection fraction and the ascending aortic diameter showed a statistically significant decrease than normotensive.Conclusion: We would conclude to say that the Doppler parameters of ascending aortic blood flow are abnormal in hypertensives. This altered haemodynamics may lead to further ill effects by way of altered peripheral haemodynamics. This Doppler evaluation of ascending aortic blood flow can be developed as a clinical tool for evaluating hypertensives and assessing the benefit of treatment of hypertension.

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Research on S Type Acceleration and Deceleration Time Planning Algorithm with Beginning and End Speed Non-zero

Journal of Mechanical Engineering ◽

10.3901/jme.2016.23.199 ◽

2016 ◽

Vol 52 (23) ◽

pp. 199 ◽

Cited By ~ 2

Author(s):

Liangliang YANG

Keyword(s):

Acceleration And Deceleration ◽

Planning Algorithm ◽

Time Planning ◽

Deceleration Time

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Evaluation of Left Ventricular Outflow Gradients During Staged Exercise Stress Echocardiography Helps Differentiate Pediatric Patients With Hypertrophic Cardiomyopathy From Athletes and Normal Subjects

Pediatric Exercise Science ◽

10.1123/pes.2020-0217 ◽

2021 ◽

pp. 1-7

Author(s):

Mansi Gaitonde ◽

Shannon Jones ◽

Courtney McCracken ◽

Matthew E. Ferguson ◽

Erik Michelfelder ◽

...

Keyword(s):

Hypertrophic Cardiomyopathy ◽

Left Ventricular ◽

Exercise Stress ◽

Peak Exercise ◽

Acceleration Time ◽

Left Ventricular Outflow ◽

Stage 1 ◽

Normal Controls ◽

Peak Gradient ◽

Deceleration Time

Background: Elevated left ventricular outflow tract (LVOT) gradients during exercise can occur in patients with hypertrophic cardiomyopathy (HCM) as well as in athletes and normal controls. The authors’ staged exercise protocol calls for imaging at rest and during each stage of exercise to evaluate the mechanism of LVOT obstruction at each stage. They investigated whether this staged approach helps differentiate HCM from athletes and normal controls. Methods: They reviewed pediatric exercise stress echocardiograms completed between January 2009 and October 2017 at their center and identified those with gene-positive HCM, athlete’s heart, and normal controls. Children with inducible obstruction (those with no LVOT gradient at rest who developed a LVOT peak gradient > 25 mm Hg during exercise) were included. LVOT peak gradient, velocity time integral, acceleration time, and deceleration time were measured at rest, submaximal stages, and peak exercise. Results: Compared with athletes, HCM patients had significantly higher LVOT peak gradients at rest (P = .019), stage 1 of exercise (P = .002), and peak exercise (P = .051), as well as a significantly higher change in LVOT peak gradient from rest to stage 1 (P = .016) and from rest to peak (P = .038). The acceleration time/deceleration time ratio of the LVOT Doppler was significantly lower in HCM patients compared with normal controls at peak exercise. Conclusions: The HCM patients who develop elevated LVOT gradients at peak exercise typically manifest early obstruction in the submaximal stages of exercise, which helps to differentiate them from athletes and normal controls.

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Effects of Voluntary Blinks on Saccades, Vergence Eye Movements, and Saccade-Vergence Interactions in Humans

Journal of Neurophysiology ◽

10.1152/jn.2002.88.3.1220 ◽

2002 ◽

Vol 88 (3) ◽

pp. 1220-1233 ◽

Cited By ~ 46

Author(s):

H. Rambold ◽

A. Sprenger ◽

C. Helmchen

Keyword(s):

Eye Movements ◽

Peak Velocity ◽

Saccade Onset ◽

Vertical Saccades ◽

Acceleration And Deceleration ◽

Tightly Coupled ◽

Measured Effect ◽

Straight Ahead ◽

Omnipause Neurons ◽

Saccade Duration

Blinks are known to change the kinematic properties of horizontal saccades, probably by influencing the saccadic premotor circuit. The neuronal basis of this effect could be explained by changes in the activity of omnipause neurons in the nucleus raphe interpositus or in the saccade-related burst neurons of the superior colliculus. Omnipause neurons cease discharge during both saccades and vergence movements. Because eyelid blinks can influence both sets of neurons, we hypothesized that blinks would influence the kinematic parameters of saccades in all directions, vergence, and saccade-vergence interactions. To test this hypothesis, we investigated binocular eye and lid movements in five normal healthy subjects with the magnetic search coil technique. The subjects performed conjugate horizontal and vertical saccades from gaze straight ahead to targets at 20° up, down, right, or left while either attempting not to blink or voluntarily blinking. While following the same blink instruction, subjects made horizontal vergence eye movements of 7° and combined saccade-vergence movements with a version amplitude of 20°. The movements were performed back and forth from two targets simultaneously presented nearby (38 cm) and more distant (145 cm). Small vertical saccades accompanied most vergence movements. These results show that blinks change the kinematics (saccade duration, peak velocity, peak acceleration, peak deceleration) of not only horizontal but also of vertical saccades, of horizontal vergence eye movements, and of combined saccade-vergence eye movements. Peak velocity, acceleration, and deceleration of eye movements were decreased on the average by 30%, and their duration increased by 43% on the average when they were accompanied by blinks. The blink effect was time dependent with respect to saccade and vergence onset: the greatest effect occurred 100 ms prior to saccade onset, whereas there was no effect when the blink started after saccade onset. The effects of blinks on saccades and vergence, which are tightly coupled to latency, support the hypothesis that blinks cause profound spatiotemporal perturbations of the eye movements by interfering with the normal saccade/vergence premotor circuits. However, the measured effect may to a certain degree but not exclusively be explained by mechanical interference.

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