Critical Flicker Fusion Frequency Research Articles

PBDB-T/Pentacene-Based Organic Optoelectronic Synaptic Transistor with Adjustable Critical Flicker Fusion Frequency for Dynamic Vision.

In the era of the Internet of Things and the rapid progress of artificial intelligence, there is a growing demand for advanced dynamic vision systems. Vision systems are no longer confined to static object detection and recognition, as the detection and recognition of moving objects are becoming increasingly important. To meet the requirements for more precise and efficient dynamic vision, the development of adaptive multimodal motion detection devices becomes imperative. Inspired by the varied response rates in biological vision, we introduce the concept of critical flicker fusion frequency (cFFF) and develop an organic optoelectronic synaptic transistor with adjustable cFFF. In situ Kelvin probe force microscopy analysis reveals that light signal recognition in this device originates from charge transfer in the poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene)-co-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)-benzo[1,2-c:4,5-c']dithiophene-4,8-dione)] (PBDB-T)/pentacene heterojunction, which can be effectively modulated by gate voltage. Building upon this, we implement different cFFF within a single device to facilitate the detection and recognition of objects moving at different speeds. This approach allows for resource allocation during dynamic detection, resulting in a reduction in power consumption. Our research holds great potential for enhancing the capabilities of dynamic visual systems.

Transcranial Direct Current Stimulation Combined With Aerobic Exercise for the Treatment of Chronic Nonspecific Low Back Pain

Objective: The purpose of the study is to determine the effectiveness of transcranial direct current stimulation (tDCS) combined with aerobic exercise in the short, medium, and long term. Methods: Two-arms triple-blind randomized controlled trial. Thirty-eight subjects with a diagnosis of nonspecific chronic low back pain. Experimental group will receive real-tDCS and aerobic exercise and control group will be treated with sham tDCS and aerobic exercise. Pain intensity, pressure pain, disability, kinesiophobia, quality of life, catastrophism, heart rate variability, and critical flicker fusion frequency will be measured before and after each session and at 3- and 6-month follow-up. Discussion and Conclusion: This study introduces the novel measurement of heart rate variability and cortical arousal to explore their potential in understanding the effects of tDCS on pain modulation. Trial Registration: ClinicalTrials.gov ID NCT05830851. Date of registration: April 14, 2023.

Efficacy of psychometric hepatic encephalopathy score versus critical flicker fusion frequency in diagnosing subclinical uremic encephalopathy in patients with chronic kidney disease – A pilot study

Background: Cognitive dysfunction can occur in a significant proportion of patients with chronic kidney disease (CKD). Subclinical uremic encephalopathy (SUE) is defined as cognitive impairment (CI) greater than expected for normal aging and educational level. SUE is characterized by declining cognitive function that becomes irreversible if left untreated. However, there is no specific test to confirm the diagnosis of SUE. Aim and Objectives: To determine the diagnostic accuracy of psychometric hepatic encephalopathy score (PHES) and critical flicker fusion frequency (CFFF) tests in SUE in CKD Stage 5 patients and to estimate the prevalence of CI among CKD patients. Materials and Methods: It was a cross-sectional study conducted at a tertiary care center in Chennai, South India, during September 2022–October 2022, among 35 patients diagnosed with CKD Stage 5. All patients were subjected to MMSE (Mini-mental state examination), PHES test, and CFFF test consecutively and their scores were recorded. The collected data were analyzed with IBM SPSS Statistics for Windows, Version 29.0. The scores of PHES and CFFF were compared against MMSE and their diagnostic accuracy was tested using the receiver operating characteristics curve (ROC) along with sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy, and P < 0.05 was considered statistically significant. Results: Of all 35 patients, 19 (54%) were males with a median age of 60 years. Fifteen patients (43%) were on hemodialysis. The prevalence of CI among CKD patients was 60%. CI was detected with MMSE in 21 patients (60%). Out of the 21 patients, 18 were positive with PHES (P < 0.01) and 19 were positive with CFFF (P < 0.05). PHES showed better sensitivity (90.9%), specificity (90.0%), PPV (90.9%), and NPV (90.0%) than CFFF, which showed a sensitivity of (89.7%), specificity (85.3%), PPV (86.8%), and NPV (87.5%). PHES was more accurate (accuracy – 90.5%) than CFFF (85.5%). 29 (83%) patients completed MMSE and 24 (69%) patients completed PHES, whereas all patients (100%) completed CFFF test. The average time taken in minutes to complete MMSE, PHES, and CFFF was 14.68 ± 2.02, 30.11 ± 4.13, and 5.48 ± 1.44 min, respectively. Cognitive function scores did not differ significantly with the duration of CKD and between patients with CKD receiving dialysis. Conclusion: Both PHES and CFFF are effective in detecting impaired cognition and can be used as reliable tools in the diagnosis of SUE. Moreover, CFFF was less time-consuming and easier to complete, making it an ideal bedside test. The prevalence of CI among CKD patients was considerably high (60%). Hence, early detection and treatment would prevent patients from going into overt uremic encephalopathy where CI can become irreversible.

Effect of habitual breakfast skipping on information processing capacity, cortical response, and cognitive flexibility among medical collegiate- a cross-sectional study.

Breakfast replenishes glucose homeostasis and provides other micro-nutrients for the normal functioning of the body after a long night at night. Habitually skipping breakfast leads not only to metabolic disturbances but also to neurocognitive impairment. Hence, the current study wascarried out to study the effect of skipping breakfast on neurocognitive functions. A 9-item breakfast questionnaire was distributed online to students for identifying habitual breakfast skippers from non-skippers based on inclusion criteria. Random blood glucose was noted and visual and auditory reaction time, critical flicker fusion frequency, and Stroop test were assessed in both groups to assess cognition. Forty one habitual breakfast skippers who met the inclusion criteria showed increased visual reaction time, and auditory reaction time indicating cognitive impairment. A significant reduction in the Stroop test was observed among the non-skipper group when compared to the skipper group. This study suggests that skipping breakfast diminishes neurocognitive functions like problem-solving, planning, judgment, information retention, and reasoning.

Modeling the critical fliker fusion frequency in the human visual system

The temporal resolving power of the visual system is essential for the perception of the objective world. The lowest sampling rate of a sequence of images at which perception becomes fused is called the critical flicker fusion frequency. The variety of experimental data on critical frequency thresholds can be explained from a point of view of a model of the contrast sensitivity of the visual system that based on the tremor modulation signal. The model describes the dependence of critical frequency on stimulus brightness, adaptation brightness, duration, and the angular size of the stimulus. This model demonstrates that for bright stimuli with short duration and a large angular size, critical frequency values lie in the range up to 1000 Hz; the frame rate of 300-500 Hz should be considered optimal for the visual system; for small-sized angular stimuli, the critical frequency lies in the low-frequency region. Differences in the rate of flicker fusion can be explained by temporal sensitivity of magno- and parvocellular neurons.

Comment on Muth et al. Assessing Critical Flicker Fusion Frequency: Which Confounders? A Narrative Review. Medicina 2023, 59, 800.

We first want to thank the authors of the excellent review for their contributions to summarizing the confounders associated with critical flicker fusion frequency (CFFF) [...].

Internet addiction induced critical fusion frequency among young adults.

Critical flicker fusion frequency (CFF) is the frequency at which flickering light can be perceived as continuous and it is used to assess the processing of temporal vision. It is of interest to compare critical fusion frequency (CFF) in mild, moderate & severe internet users. Cross sectional observation study was done among 350 professional students. Internet addictions for around 372 professional students & internet addiction was evaluated by Young's scale of Internet Addiction questionnaire in the age group 18-25 years. CFF was measured using an in-house built LED-based CFF M1 Model instrument. A total of 372 participants (in age group 19-22 years) were recruited. Of the participants 65 % of them were mild internet addictors, 48% were moderate and 7% were severe internet adductors. Among the internet usage, the Kruskal-Wallis test showed a significant difference in internet addiction score, duration of internet usage (hours) and average Critical fusion frequency (Hz) (P<0.001). For the average critical fusion frequency (Hz), the Dwass-Steel-Critchlow-Fligner test showed significant pairwise comparisons between the following: (1) mild internet addictor's vs moderate internet addictors and (2) Mild internet addictors versus severe internet addictors (p<0.001). Critical flicker fusion frequency(CFF) as it is an easy, quick, and non-invasive technique used as a general indicator of cortical processing, visual persistence for cognitive flexibility.

Phantom array and stroboscopic effect visibility under combinations of TLM parameters

Solid-state light sources can be more prone to larger temporal light modulation (TLM) than conventional sources. TLM visibility depends on wave shape, frequency, modulation depth and duty cycle, and is affected by the sensitivity of the observer. TLM can be visible well above the critical flicker fusion frequency, when there is relative movement between the observer’s eyes and light source, lighted space or moving objects in the field of view. This human subjects experiment explored visibility of the stroboscopic effect (SE) versus the phantom array effect (PAE) with targeted tasks under 74 TLM waveforms. The results showed the SE visibility peaks between 90 Hz and 120 Hz, while the PAE visibility peaks between 500 Hz and 1000 Hz. The phantom array is visible to sensitive participants at 6000 Hz. Both effects are more visible under rectangular versus sinusoidal TLM, higher modulation, and when duty cycles are 10% or 30% versus 50%. Higher sensitivity participants, differentiated using the Leiden Visual Sensitivity Scale, rated TLM waveforms as more visible, especially those inherently harder to see. This work lays a foundation for a PAE metric and guides driver and dimmer designers toward electronic circuits that minimize the visibility of TLM in LED products.

Assessing Critical Flicker Fusion Frequency: Which Confounders? A Narrative Review.

The critical flicker fusion frequency (cFFF) refers to the frequency at which a regularly recurring change of light stimuli is perceived as steady. The cFFF threshold is often assessed in clinics to evaluate the temporal characteristics of the visual system, making it a common test for eye diseases. Additionally, it serves as a helpful diagnostic tool for various neurological and internal diseases. In the field of diving/hyperbaric medicine, cFFF has been utilized to determine alertness and cognitive functions. Changes in the cFFF threshold have been linked to the influence of increased respiratory gas partial pressures, although there exist inconsistent results regarding this effect. Moreover, the use of flicker devices has produced mixed outcomes in previous studies. This narrative review aims to explore confounding factors that may affect the accuracy of cFFF threshold measurements, particularly in open-field studies. We identify five broad categories of such factors, including (1) participant characteristics, (2) optical factors, (3) smoking/drug use, (4) environmental aspects, and (5) breathing gases and partial pressures. We also discuss the application of cFFF measurements in the field of diving and hyperbaric medicine. In addition, we provide recommendations for interpreting changes in the cFFF threshold and how they are reported in research studies.

Dynamics of the functional state of students of the profession “secretary-referent” during the internship

Introduction. During the apprenticeship, students training as secretaries are exposed to a complex of professional and industrial factors that cause functional changes in the body. &#x0D; Materials and methods. Thirty 18-19 years girls were divided according to the Eysenck’s psychological types of personality and to Strelau theory into more adapted and less adapted groups, Heart rhythm variability, mental and physical capabilities, the lability of the visual analyzer, and the psycho-emotional state were evaluated at the beginning and the end of apprenticeship.&#x0D; Results. Trend in heart rate variability in the group of less and more adapted cases differed: the total power of the TR spectrum (ms2) decreased by 50.4% in the group of more adapted, by 54.48% in the group of less adapted. The stress index was 126.9% in the group of more adapted, and 131.9% in the group of the less adapted students. After the apprenticeship work, efficiency decreased by 31.3%, the degree of workability increased by 25.0%, mental stability fell by 16.9%. &#x0D; After the apprenticeship, students’ well-being according to the Scores of Well-being, Activity, Mood (WAM) decreased by 24.5% (p&lt;0.001), activity decreased by 21.6% (p&lt;0.001); mood worsened by 7.4%. Before work practice, critical flicker fusion frequency (CFFF) was 43.4±0.3 Hz, and after it 39.6 ± 0.4 Hz (p&lt;0.001).&#x0D; Limitations. The study was limited to a sample of students learning as secretaries, by age, gender and apprenticeship duration.&#x0D; Conclusion. Heart rate variability indicators reflect the tension of regulatory systems in the process of learning practical skills, caused by the occurrence of situations in apprenticeship conditions, which indicates the need of improving methodological approaches to its management, purposeful development of the first key professionally significant functions from the beginning of training, the implementation of physical exercises during the physical education classes, taking into account the specifics of the future profession. A more discernible degree of tension in the regulation processes in the group of less adapted students (a decrease in the total power of the TR spectrum (ms2) by 54.48% and an increase in IN by 31.9% in this group), and the psycho-emotional state of secretaries-referents, requires a personalized approach to apprenticeship managing.

Determining Work-Rest Schedules for Visual Tasks That Use Optical Head-Mounted Displays Based on Visual Fatigue and Visually Induced Motion Sickness Recovery.

This study aimed to determine work-rest schedules for visual tasks of different lengths by evaluating visual fatigue and visually induced motion sickness (VIMS) using an optical head-mounted display (OHMD). Thirty participants were recruited to perform 15 and 30 min visual tasks using an OHMD. After completing each visual task, participants executed six levels of rest time. Critical flicker fusion frequency (CFF) values, relative electroencephalography indices, and Simulator Sickness Questionnaire (SSQ) scores were collected and analyzed. Results indicated that after completing the 15 and 30 min visual tasks, participants experienced visual fatigue and VIMS. There was no significant difference between baseline CFF values, four electroencephalography relative power index values, and SSQ scores when participants completed a 15 min visual task followed by a 20 min rest and a 30 min visual task followed by a 30 min rest. Based on our results, a 20 min rest for visual fatigue and VIMS recovery after a 15 min visual task on an OHMD and a 25 min rest for visual fatigue and VIMS recovery after a 30 min visual task on an OHMD are recommended. This study suggests a work-rest schedule for OHMDs that can be used as a reference for OHMD user guidelines to reduce visual fatigue and visually induced motion sickness.

The functional state of the visual analyzer and characterological features of children at a primary school age with orthophoria and heterotropia

Objective. To analyze the functional state of the visual analyzer and characterological features of children at a primary school age with orthophoria and heterotropia.Materials and methods. Eighty-four children (168 eyes) aged 6-11 years were examined. Two groups comparable in age and gender were formed. Group 1 included 35 children (70 eyes) with orthophoria with moderate degree hyperopia Hm 4.1 [1.0; 8.75] Dptr; Group 2 consisted of children with concomitant convergent strabismus with a moderate degree hyperopia Hm 4.3 [0.75; 9.75] Dptr - 49 patients (98 eyes). To study the properties of the nervous system (NS) hardwaresoftware complex “NS-Psychotest” (Neurosoft LLC, Ivanovo, Russia, http://neurosoft. com/ru) was used. Neurodynamic indices of sensorimotor reaction were determined according to the methods “Simple visual-motor reaction” (PMR), “Distinguishing reaction” (DR), “Choice reaction” (PC), “Reaction to a moving object” (RMA), “Critical flicker fusion frequency” (CFF), Lusher’s color test.Results. Concomitant strabismus in group 2 children significantly increased “Simple visual-motor reaction” (SVMR), “Discrimination reaction” (RR) and “Choice reaction” (RС) by 43 ms, 80.8 and 57.8 ms, respectively (p&lt;0.05), compared to the group of children with orthophoria, indicating reduced mobility of nervous processes and predominance of inhibitory processes in the central nervous system (CNS).Conclusion. It follows from the results obtained that the presence of heterotrophy in group 2 children reliably leads to a decrease in the mobility of nervous processes and the predominance of inhibitory processes in the CNS. The combination of low reaction rate and expressed inertness of nervous processes in children of the 2nd group indicates a mismatch in the relationship between the centers of the visual and motor analyzers.

Role of ON and OFF Visual Pathways in Rod- and Cone-Driven Flicker Responses.

To evaluate the effects of various retinal neurotransmitters on temporal resolution, particularly, on the Critical Flicker Fusion Frequency (CFF), which has been previously applied in ophthalmic pathophysiologic research. A binocular physiologic electroretinogram was performed on adult mice. Animals in the control group were injected in the right eye with 1 μL of phosphate-buffered saline (PBS). Animals in the experimental group were injected in the left eye with 1 μL of PBS and in the right eye with 1 μL of PBS to which different molecules were added: 2-amino-4-phosphonobutyric acid (APB), Glutamate, γ-aminobutyric acid (GABA), 6,7-dinitroquinoxaline-2,3-dione (DNQX), Bicuculline, Glycine, and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES). Initially, rod response was recorded and later the cone response. APB suppressed the rod-driven, but not the cone-driven flicker response. The other agents severely affected the lower flickering frequency response amplitude, in particular, at 3 Hz. The threshold of CFF was lowered from 50 Hz to 40 Hz after applying APB, Glycine, and HEPES. GABA remarkably enhanced rod-driven and cone-driven flicker response at 3 Hz, whereas Glutamate and GABA/Glutamate only did in rod-driven flicker response. Both ON and OFF visual pathways were implied in cone-driven response, but only the ON visual pathway appears to play a relevant role in rod-driven flicker response. Flicker response seems to be enhanced by horizontal cells both in rod-driven and cone-driven response. In addition, due to the greater sensitivity of the flicker at low frequencies, it is suggested that pathophysiological studies should be carried out at said frequencies.

Usefulness of critical flicker fusion frequency measurement and its laterality for evaluating compressive optic neuropathy due to pituitary neuroendocrine tumors.

Critical flicker fusion frequency (CFF) is a short but sensitive method for evaluating optic nerve function. We measured CFF in patients with pituitary neuroendocrine tumors (Pit-NETs) to assess its usefulness. Data from 184 patients with nonfunctioning Pit-NETs, who had been treated with transsphenoidal surgery and had no medical history of eye diseases, was used in this retrospective study. Visual acuity decline (VAD) was defined as > 0.10 reduction in logMAR visual acuity and CFF decline (CFD) was defined as CFF value < 35Hz. Visual field defect (VFD) was evaluated by automated perimetry on a Humphrey visual field analyzer. Potential associations between abnormal test results and tumor height from the suprasellar were analyzed. Contact between the optic nerve or chiasma and the tumor was present and absent in 161 and 23 patients, respectively. In patients showing contact, the difference in CFF between the left and right eyes was larger (p = 0.0008), and the optimal cutoff value using the receiver operating characteristic curve was 3Hz. Therefore, ≥ 3Hz was considered positive for CFF laterality (CFL), the most prevalent condition. Tumor height was lower in patients with CFL positivity compared to those with VAD or VFD (p < 0.01). The prevalence of test abnormalities was the highest for small tumors compared to those of other tests. Changes in CFL permit early detection of Pit-NETs. Our results indicate that CFF laterality can be seen in the early stages of compressive optic neuropathy due to Pit-NET.

Đánh giá khả năng chịu đựng các yếu tố lao động bay của học viên phi công quân sự Việt Nam và Liên bang Nga

The article studies the characteristics of tolerance to the occupational factors of flying labor in military pilots (MP) of the Socialist Republic of Vietnam with the aim of fulfill the psychophysiological training system for military pilots. The study involved 17 Vietnamese and 24 Russian MP between the ages of 19 and 22. Conducted an endurance assessment against flight factors such as overload, hypoxia and effects of balance dynamics on the basis of using statoergometric, hypoxia test and vestibular organ test “OR-10”. Before and after being subjected to the above effects, MP were evaluated for psychophysiological characteristics by measuring critical flicker fusion frequency (CFFF) and reaction time test (RTT) and physiological indicators about computer balance ability during hypoxia. In addition, height and weight indexes were also included in the study. The results showed that there was a significant difference between the two study groups with the difference in height, weight, BMI and flying overload capacity in the Russian MP group were higher. At the same time, there was also a difference in psychophysiological indicators between the two groups. Assessment of hypoxia tolerance and cochlear vestibular testing (OR-10) based on computerized balance indices showed different predispositions for each group. This is because in the Vietnamese MP group, there has appeared an adaptive mechanism in a state of greater exertion than in the Russian group. The results of the study show that it is necessary to improve the psychophysiological training system for Vietnamese pilots in order to improve their ability to resist the effects of occupational factors during flight operations highly maneuverable aircraft manufactured by the Russian Federation.

EEG microstate changes according to mental fatigue induced by aircraft piloting simulation: An exploratory study

BackgroundA continuous flight task load can induce fatigue and lead to changes in electroencephalography (EEG). EEG microstates can reflect the activities of large-scale neural networks during mental fatigue. This exploratory experiment explored the effects of mental fatigue induced by continuous simulated flight multitasking on EEG microstate indices. MethodsTwenty-four participants performed continuous 2-hour aircraft piloting simulation while EEG were recorded. The Stanford sleepiness scale (SSS) and critical flicker fusion frequency (CFF) were measured before and after the task. Microstate analysis was applied to EEG. Four microstate classes (A–D) were identified during the pre-task, post-task, beginning, and end phases. The effects of mental fatigue were analyzed. ResultsCompared with the pre-task, the post-task had a higher global explained variance (GEV) and time parameters of class C but lower occurrence and coverage of class D. The end had a higher GEV but lower duration and coverage of class D than at the beginning. After 2 h of multitasking, the transition probability between A and D, and between B and D decreased but between A and C increased. Subjective fatigue scores were negatively correlated with occurrence and coverage of class D. Task performance was negatively correlated with duration and coverage of class C but positively correlated with duration and occurrence of class B. ConclusionTime parameters and transition probability of EEG microstates can detect mental fatigue induced by continuous aircraft piloting simulation. The global brain network activation of mental fatigue can be detected by EEG microstates that can evaluate flight fatigue.

Effects of three-dimension movie visual fatigue on cognitive performance and brain activity.

To further develop three-dimensional (3D) applications, it is important to elucidate the negative effects of 3D applications on the human body and mind. Thus, this study investigated differences in the effects of visual fatigue on cognition and brain activity using visual and auditory tasks induced by watching a 1-h movie in two dimensions (2D) and 3D. Eighteen young men participated in this study. Two conditions were randomly performed for each participant on different days, namely, watching the 1-h movie on television in 2D (control condition) and 3D (3D condition). Before and after watching the 1-h movie on television, critical flicker fusion frequency (CFF: an index of visual fatigue), and response accuracy and reaction time for the cognitive tasks were determined. Brain activity during the cognitive tasks was evaluated using a multi-channel near-infrared spectroscopy system. In contrast to the control condition, the decreased CFF, and the lengthened reaction time and the decreased activity around the right primary somatosensory cortex during Go/NoGo blocks in the visual task at post-viewing in the 3D condition were significant, with significant repeated measures correlations among them. Meanwhile, in the auditory task, the changes in cognitive performance and brain activity during the Go/NoGo blocks were not significant in the 3D condition. These results suggest that the failure or delay in the transmission of visual information to the primary somatosensory cortex due to visual fatigue induced by watching a 3D movie reduced the brain activity around the primary somatosensory cortex, resulting in poor cognitive performance for the visual task. This suggests that performing tasks that require visual information, such as running in the dark or driving a car, immediately after using a 3D application, may create unexpected risks in our lives. Thus, the findings of this study will help outlining precautions for the use of 3D applications.

Critical Flicker Fusion Frequency and Visual Reaction Time in Six Different Colors in Students with Different Grade of the Perceived Stress

Perceived stress is the thoughts or feelings one has about their level of experienced stress. Theonset of fatigue and perceived stress could be detrimental to the cognitive functioning and ability.Visual reaction time indicates the sensory motor coordination and critical flicker fusion frequencyindicates detrimental to the cognitive functioning and ability. In this study the levels of perceivedstress and their effect on visual reaction time and critical fusion frequency is measured.Methods: A total of 75 apparently healthy students in the age group of 18-40 years students wereincluded in the study. The perceived stress scores were measured using the questionnaire andparticipants were divided into mild (group I) and moderate stress group (group II). The visualreaction time recording was done using different color like red, green, blue, yellow, purple andaqua. Critical flicker fusion frequency was also measured.Results: The average visual reaction time for red, green and blue was less when compared topurple, yellow and aqua. The mean reaction time for red color in mild stress group I (392 ± 44msec) was more when compared to group II (379 ± 40 msec). similar findings were found inall other colors except purple were mean reaction time same in both the group. There was nodifference in the CFFF between the groups.Conclusion: It found that sensory coordination in the mild stress group was diminished whencompared to participants in moderate stress group. There are no changes in cognitive ability (CFFF) between the groups.

Nocturnal Eyes in Slipper Lobsters (Decapoda Scyllaridae): Physiological and Ecological Implications of Habitat Depths for Visual Traits

The light characteristics of an ecosystem drive evolutionary adaptations in visual traits, enhancing the diversity and abundance of species living there. The visual systems of crustaceans are highly diverse and often correspond to the optical properties of their preferred environments. Although habitat depth is known to greatly influence visual specialization in marine crustaceans, it remains unclear whether depth drives visual adaptions in nocturnal species. Slipper lobsters (Scyllaridae) are nocturnal benthic marine crustaceans distributed throughout a wide range of depths. In order to understand the visual adaptive capabilities of slipper lobsters inhabiting different depths, we characterized the eye structures of a shallow-water species (Parribacus japonicas), an intermediate-depth species (Scyllarides squammosus) and a deep-water species (Ibacus novemdentatus). Moreover, we measured by electroretinogram (ERG) the spectral sensitivities and temporal resolutions for each species using the following light stimuli: UV (λmax 386 nm), blue (λmax 462 nm), green (λmax 518 nm), yellow (λmax 590 nm), and red (λmax 632 nm). Our histological experiments show that all three species possess a typical superposition compound eye with square facets, and their ERG measurements revealed a single sensitivity peak for each species. Notably, peak spectral sensitivity corresponded to habitat depth, with the estimated peak for I. novemdentatus (493.0 ± 9.8 nm) being similar to that of S. squammosus (517.4 ± 2.1 nm), but lower than that of P. japonicus (537.5 ± 9.9 nm). Additionally, the absolute sensitivities at respective peak wavelengths for I. novemdentatus and P. japonicus were higher than that of S. squammosus. No differences were observed among the three species for maximum critical flicker fusion frequency (CFFmax) across light stimuli. However, P. japonicus had lower CFFmax values than the other two species. These data suggest that all three nocturnal slipper lobsters are likely monochromatic and well adapted to dim light environments. Significantly, the deep-water slipper lobster displayed higher spectral sensitivities at shorter wavelengths than the shallow water species, but temporal resolution was not compromised.

The safety and feasibility of endoscopic submucosal dissection using a flexible three-dimensional endoscope for early gastric cancer and superficial esophageal cancer: A prospective observational study.

Endoscopic submucosal dissection (ESD) is performed as one of standard treatments for patients with early gastric cancer (EGC) and superficial esophageal squamous cancer (SESCC). A prototype of a flexible endoscope with a 3-D system has been recently developed. This study aimed to investigate the safety and feasibility of ESD using a 3-D flexible endoscope (3-D ESD) for EGC and SESCC. This single-center, prospective, observational study enrolled patients who underwent planned 3-D ESD. The clinical outcomes, including the incidence of adverse events and treatment results, were analyzed. Visibility and manipulation during 3-D ESD were evaluated using a visual analog scale (VAS). We also evaluated the effect of the 3-D system on the endoscopist using VAS and the critical flicker fusion frequency (CFFF). We analyzed 47 EGC and 20 SESCC cases. There are no bleeding cases that required transfusion and perforation during 3-D ESD in both EGC and SESCC patients. However, the incidence of delayed bleeding and delayed perforation was 1.5% (one case) each. The mean VAS scores for recognizing the submucosal layer during the submucosal dissection, visual perception of blood vessel, and depth perception were 72.7±22.2, 74.7±21.8, and 78.2±19.9, respectively. In contrast, the mean VAS score for manipulation was 25.4±19.7. Among endoscopists, there was no significant difference in the VAS of eyestrain and headache before and after ESD, and there was no significant difference in the CFFF. The safety and feasibility of 3-D ESD for EGC and SESCC are acceptable in both patients and endoscopists.