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Effects of “Short-Term” versus “Long-Term” L-Dopa Therapy in Parkinsonism on Critical Flicker Frequency
No full text This study investigated shorter and longer range effects of L-Dopa therapy in parkinsonism on critical flicker frequency (CFF) scores. Three equated groups of 15 Ss were selected to include “short-term,” “long-term,” L-Dopa patients and a control group. Binocular CFF thresholds were obtained for each S on two separate occasions. Results indicate that: (1) the control group scored significantly higher on CFF indicating superior neural integration when compared with the “short-term” or “long-term” L-Dopa group; (2) the “short-term” L-Dopa group scored significantly higher than the “long-term” L-Dopa group demonstrating better cerebral efficiency. Evidence suggests that a peculiar clinical state interfering with neural transmission may develop in parkinsonian patients on L-Dopa therapy prolonged 2 yr. or more. </jats:p
Flicker Frequency
No full textThis package includes both the dataset and the PsychoPy experiment designed to investigate flicker frequency
Inferior Parietal Lobule Encodes Visual Temporal Resolution Processes Contributing to the Critical Flicker Frequency Threshold in Humans
No full textThe measurement of the Critical Flicker Frequency threshold is used to study the visual temporal resolution in healthy subjects and in pathological conditions. To better understand the role played by different cortical areas in the Critical Flicker Frequency threshold perception we used continuous Theta Burst Stimulation (cTBS), an inhibitory plasticity-inducing protocol based on repetitive transcranial magnetic stimulation. The Critical Flicker Frequency threshold was measured in twelve healthy subjects before and after cTBS applied over different cortical areas in separate sessions. cTBS over the left inferior parietal lobule altered the Critical Flicker Frequency threshold, whereas cTBS over the left mediotemporal cortex, primary visual cortex and right inferior parietal lobule left the Critical Flicker Frequency threshold unchanged. No statistical difference was found when the red or blue lights were used. Our findings show that left inferior parietal lobule is causally involved in the conscious perception of Critical Flicker Frequency and that Critical Flicker Frequency threshold can be modulated by plasticity-inducing protocols
Korelasi NIlai Critical Flicker Frequency dengan Kadar Amonia Darah pada Ensefalopati Hepatik Minimal
Get PDFEnsefalopati hepatik minimal (EHM) merupakan variasi klinik ensefalopati hepatik (EH) yang insidennya terjadi pada 60 – 70 % pasien dengan sirosis hati. Kondisi ini terdiri dari penurunan kognitif yang diamati pada pasien dengan sirosis hati yang tidak memiliki klinis nyata ensefalopati. Ensefalopati hepatik minimal akan menyebabkan berkurangnya kualitas hidup dan mempengaruhi kemampuan dari pasien untuk melakukan tugas sehari-hari. Pengukuran kadar amonia darah sebagai modalitas diagnostik ensefalopati hepatik dapat dilakukan untuk mengkonfirmasi diagnosis pada pasien dengan penyakit hati kronik. Belakangan ini, tes Critical Flicker Frequency (CFF) telah dikembangkan untuk diagnosis ensefalopati hepatik minimal, di mana CFF ini memiliki keuntungan karena tidak tergantung pada bahasa, verbal, penghitungan atau numerik dan penggunaaanya telah dilakukan di banyak negara. Penelitian ini dilakukan untuk menilai korelasi Critical Flicker Frequency dengan kadar amonia darah pada ensefalopati hepatik minimal. Penelitian dilakukan di Instalasi Rawat Inap dan Rawat Jalan Bagian Penyakit Dalam RSUP Dr. M Djamil Padang selama 6 bulan. Subjek penelitian adalah pasien sirosis hati yang telah didiagnosis secara klinis dan USG abdomen. Dari hasil penelitian didapatkan korelasi yang bermakna (p<0,001) antara penurunan nilai Critical Flicker Frequency dengan peningkatan kadar amonia darah pada ensefalopati hepatik minimal dengan gradasi sangat kuat (r=-0,826). Disimpulkan bahwa penurunan nilai Critical Flicker Frequency berkorelasi dengan peningkatan kadar amonia darah pada ensefalopati hepatik minimal.
Kata kunci :
Critical Flicker Frequency, amonia darah, ensefalopati hepatik minima
Inferior parietal lobule encodes visual temporal resolution processes contributing to the critical flicker frequency threshold in humans
No full textThe measurement of the Critical Flicker Frequency threshold is used to study the visual temporal resolution in healthy subjects and in pathological conditions. To better understand the role played by different cortical areas in the Critical Flicker Frequency threshold perception we used continuous Theta Burst Stimulation (cTBS), an inhibitory plasticity-inducing protocol based on repetitive transcranial magnetic stimulation. The Critical Flicker Frequency threshold was measured in twelve healthy subjects before and after cTBS applied over different cortical areas in separate sessions. cTBS over the left inferior parietal lobule altered the Critical Flicker Frequency threshold, whereas cTBS over the left mediotemporal cortex, primary visual cortex and right inferior parietal lobule left the Critical Flicker Frequency threshold unchanged. No statistical difference was found when the red or blue lights were used. Our findings show that left inferior parietal lobule is causally involved in the conscious perception of Critical Flicker Frequency and that Critical Flicker Frequency threshold can be modulated by plasticity-inducing protocols. © 2014 Nardella et al
The visual acuity and critical flicker frequency after treatment in cases 1–7.
No full textThe visual acuity and critical flicker frequency after treatment in cases 1–7.</p
A study on critical flicker frequency in Migraineurs.
Get PDFMigraine is a condition wherein a variety of visual phenomena are
frequently encountered.
Migraine with and without aura involve changes in visual
perceptions during an attack.
Scintillations, scotomata and fortification spectra characterize the
visual aura. However, blurring of vision and photosensitivity are seen
even among those patients who do not experience visual aura.
Visual changes that occur during an attack of migraine help in
clarifying the clinical picture. However, the visual response during the
inter-attack period also provide valuable information. Few studies that
exist in this area point to differences in visual processing in migraine
patient, even when they are not experiencing an attack.
The human visual system processes information from the
environment in three ways: spatially, temporally and chromatically. In
migraine, responses to spatial stimuli have been most frequently
investigated.
Few studies have evaluated the temporal responsiveness of visual
system in migraineurs. Khalil et al investigated temporal contrast
sensitivity in migraineurs. Coleston et al investigated temporal
responsiveness of the visual system through background modulation
method.7 Critical flicker frequency is one such simple test to discern the
temporal responsiveness of the visual system.
AIM OF THE STUDY :
• To assess the temporal responsiveness of the visual system in migraineurs.
• To compare the critical flicker frequency in migraineurs with aura and without aura.
• To assess the temporal responsiveness of the visual system in migraineurs with visual stimuli as migraine trigger.
SUMMARY AND CONCLUSION :
The temporal responsiveness of the visual system is reduced in migraineurs. This is comparable with most studies conducted earlier.
The critical flicker frequency is lowest in migraineurs with aura followed by migraineurs without aura and highest in controls. The
observed difference in the three groups is statistically significant.
The temporal responsiveness of the visual system is lowered in migraineurs whose migraine headache is triggered by visual stimuli.
Among the sub groups whose migraine headache is triggered by visual stimuli, temporal responsiveness is lower in migraineurs with aura
compared to migraineurs without aura
Diurnal changes of critical flicker frequency in patients with liver cirrhosis and their relationship with sleep disturbances
No full textBackground: We aimed to measure the diurnal changes of critical flicker frequency in healthy subjects and cirrhotic patients and to investigate their relationship with sleep disturbance. Methods: Cirrhotic patients and healthy volunteers were included. All groups completed the Pittsburgh Sleep Quality Index and a simple sleep questionnaire. Sleep disturbance was defined as a Pittsburgh Sleep Quality Index score of >5. Critical flicker frequency was measured twice a day to detect diurnal abnormalities. Results: Overall, 59 cirrhotic patients (54.2% males, Mean Age 59 +/- 11 years) and 18 controls (39.9% males, Mean Age 58 +/- 9 years) were included. Sleep disturbances were more common in cirrhotics (66.1%) than controls (38.9%, p < 0.05). In cirrhotics, the critical flicker frequency was not related to decompensation. The nocturnal values were higher than the morning values in cirrhotics (64.4%), but not in controls (p < 0.0001). Additionally, sleep disturbances were more common in cirrhotics who had higher nocturnal values (p < 0.05). Conclusions: Changes in the diurnal critical flicker frequency were observed in cirrhotics but not in controls. Sleep disturbances in cirrhotics appear to be associated with deviations of the diurnal rhythm of critical flicker frequency rather than with clinical parameters such as the clinical stages of cirrhosis and the Model For End-Stage Liver Disease and Child-Pugh scores. (C) 2014 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved
Wavelength Effects on Critical Flicker Frequency in Human Infants
No full text We examined 3-mo.-old human infants' ability to detect flicker in 454-nm blue and 627-nm red lights at 1.5 log cd/m2. Infants showed the same critical flicker frequency (CFF) to both wavelengths, suggesting that retinal cones mediate the detection of flicker at this luminance level. Infants' CFFs for chromatic stimuli were much lower than those reported for achromatic stimuli and also much lower than adults' CFFs tested under the same conditions. </jats:p
Flicker frequency responses are normal in the absence of TRIP8b.
No full text<p><i>A)</i> Representative waveforms from flicker ERGs of WT, TRIP8b<sup>−/−</sup>, and HCN1<sup>−/−</sup> (n = 3 mice for each genotype). Dark-adapted mice were stimulated with a flash intensity of 3.1 cd.s/m<sup>2</sup> at frequencies of 0.5, 1, 2, 3, 5, 7, 10, 12, 15, 18, 20, and 30 Hz. <i>B)</i> ERG amplitudes plotted as a function of flicker frequency.</p
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