- BOOK THE WAY TO Original (PDF)
- the monthly aspectarian january Manual
- vjdbhog.tk Ebooks and Manuals
- ISBN 13: 9782294700538
Triggering of express type of saccades is believed to involve a shorter circuit, e. The second goal of this study is to examine accuracy and speed characteristics of saccades. Saccade velocity depends mainly on function of brainstem structures Paramedian Pontine reticular Formation — PPRF for horizontal saccades, the rostral interstitial nucleus of medial longitudinal fasciculus — riMLF for vertical ; accuracy of saccades depends on both cortical and subcortical areas Leigh and Zee, The metrics and dynamics of saccadic eye movements have not yet been studied in patients with DLB.
In the literature, the effect of normal aging on the accuracy of saccades is controversial. For horizontal saccades in healthy elderly, some studies Sharpe and Zackon, ; Tedeschi et al. However, many other studies Warabi et al. A similar controversy exists for vertical saccades Huaman and Sharpe, ; Yang and Kapoula, On the other hand, abnormality in accuracy of saccades has been found in patients with dementia, such as AD, frontotemporal dementia and semantic dementia Shafiq-Antonacci et al.
Concerning the speed of saccades many studies described reduction in peak velocity in normal elderly relative to young subjects Sharpe and Zackon, ; Tedeschi et al. Note that in another study Munoz et al. Thus whether saccade accuracy and speed are subject to aging is controversial. But there is evidence for their abnormalities in dementia.
As DLB patients are reported to have both cortical and subcortical deficits we expect to find abnormalities in all parameters of saccades latency, accuracy and speed. Finally, patients with DLB are known to have cognitive performance with high fluctuation of attention. We wondered to what extent clinically assessed fluctuation is associated with variability in saccade parameters.
A few previous studies Munoz et al. More recently, the former group also reported high variability of saccade latency in elderly Peltsch et al. High variability of saccade latency in studies with patients can point particular neural deficits. For instance, Blekher et al. Thus, the present study including variability of all parameters allows complete characterization of saccade performance in DLB patients.
Ten healthy subjects aged between 65 and 88 years mean No subject showed visual, neurological, psychiatric disorders or received medication with neural system effects.
BOOK THE WAY TO Original (PDF)
Recruitment was done using the consensus guidelines to diagnose DLB. All DLB patients had progressive cognitive decline of sufficient magnitude to interfere with normal social or occupational function and at least two following signs: fluctuating cognition with pronounced variation in attention and alertness, visual hallucinations and spontaneous features of parkinsonism. Moreover, DLB patients were different from Alzheimer patients by their neuropsychological characteristics sub cortico-frontal memory profile, visuo-spatial deficits, executive syndrome. Subjects with other cerebral pathology e.
All subjects with known history of macular degeneration or coexisting medical illness that could interfere with cognitive or visual testing were excluded. For 4 of 19 subjects no eye movement recording was possible because of recording difficulty or refusing the task.
Ten patients with DLB completed all the oculomotor tests. Their ages were from 73 to 89 years mean Demographical and clinical characteristics of these groups were shown in Table 1. Informed consent was obtained from all subjects after the nature of the procedure had been explained.
The visual display, shown in Figure 1 A, was composed by five white luminous dots angular size 0. Figure 1. Experimental design.
- BLUE PLAGUE Original (PDF).
- Author Contributions!
- Original Research ARTICLE!
- ORL, ophtalmologie, chirurgie maxillofaciale et stomatologie?
- My Shopping Bag.
- Erotic Nude Picture Book, Raw Real And Ready: Chloe Wet & Wild.
A Spatial arrangement. Five white luminous dots angular size 0. B,C Temporal arrangement. Each trial started by lighting one central dot during approximately — ms. For the gap task, between the fixation offset and the target onset, there was a gap of ms B ; for the overlap task, the fixation stays on ms after the target onset C.
The target, one of the eccentric dots, appears for ms. The subject was comfortably seated in an adapted chair, his head resting on a chin and frontal support. The subject viewed binocularly; all dots were highly visible. Each trial started by lighting a fixation dot at the center. The fixation dot stayed on for a random period between 1. In the gap task, there was a time interval of ms between the offset of the fixation point and the onset of the saccade target.
The target dot was kept on for 1. In the overlap task, the fixation point remained illuminated for ms after the target dot appeared. The target stayed on also for another 1. Subjects were required to make a saccade to the target point as rapidly and accurately as possible. A period of complete darkness of ms was for break. Subjects were instructed to use this period for blinks. The total mean length of each trial was about 4 s. One block for each task lasted 4—5 min.
the monthly aspectarian january Manual
Total duration of the recording was about 10 min. From these recordings we extracted calibration factors. Horizontal and vertical eye movements were recorded binocularly with the EyeLink II device. Each channel was sampled at Hz. The system has a spatial resolution of 0. The process was performed automatically by the computer, and the verification was made by visual inspection of the individual eye position and velocity traces. Peak velocity of the primary saccade were also analyzed. To evaluate the variability of each parameter, we calculated the coefficient of variation CV , the relative standard deviation expressed as a unitless proportion of each subjects mean van Beers, ; Peltsch et al.
- Tangled Souls!
- NEW BIBLE FREE EDITION PDF Original - Free E-Book Download.
- Quelques nouvelles terrifiantes (Collection 2.0.12 classique - SF, fantastique, horreur) (French Edition)!
- Gabriel Andral.
- Ophtalmologie ORL Stomatologie.
- American Hospital of Paris.
Examples of saccade latencies distribution with trials from some controls and DLB patients in the gap task. All three DLB patients show abnormal long latency.
vjdbhog.tk Ebooks and Manuals
Eye movements in the wrong direction, with latency shorter than 80 ms anticipation or longer than ms, or contaminated by blinks were rejected. Express latencies were defined as those falling in the range from 80 to ms; the rate of express saccades refers to the total number of valid saccades.
A three-way analysis of variance ANOVA was performed on individual mean latency with the between subjects factor — group healthy, DLB and the within-subjects factors — the oculomotor task gap, overlap and the direction left, right, up and down. Two-way ANOVA was performed on individual mean accuracy and velocity means with the between subjects factor healthy, DLB and the within-subjects factor saccade direction.
Post hoc comparisons were done with the Least Significant Differences test. For the rates of express latency and for the CV of each parameter, the non-parametric Mann—Whitney U -test was used for comparisons between healthy elderly and patients with DLB; for within-subjects comparisons between different directions the Friedman and Wilcoxon test was used. Figure 3 shows group mean latencies of saccades with standard error SE for different directions under the gap a and the overlap b tasks in healthy elderly and patients with DLB.
The mean values of gap effect were and ms for healthy elderly and patients with DLB, respectively. Figure 3. Group mean latency of saccades with standard error in gap and overlap tasks, for four directions in healthy elderly and DLB patients; longer latencies of saccades for DLB patients than for healthy elderly for each condition.
Figure 4 shows some individual examples of latency variability. Latencies are displayed over successive trials in the gap task.
ISBN 13: 9782294700538
The healthy subjects produce almost similar latency from one trial to next. In contrast, large fluctuations of latency are seen for the DLB subjects. Figure 4. Figure 5 shows group mean CV in latency for different direction under the gap a and the overlap b conditions in healthy elderly and patients with DLB. The Mann—Whitney U -test showed the group effect, i. Figure 5. Group mean coefficient of variation CV in saccade latency in gap and overlap tasks, for each direction in healthy elderly and DLB patients. Variability is higher for DLB patients for all conditions. Table 2 shows individual rate of express latency in the gap task for each direction.
In the gap task substantial number of express latency was found.