scholarly journals Spectral dependency of the human pupillary light reflex. Influences of pre-adaptation and chronotype

PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0253030
Author(s):  
Johannes Zauner ◽  
Herbert Plischke ◽  
Hans Strasburger
Keyword(s):  
Color Vision ◽  
Stimulus Duration ◽  
Light Stimulus ◽  
Time Of Day ◽  
Controlled Study ◽  
Pupillary Constriction ◽  
Generalized Additive Mixed Models ◽  
Additive Mixed Models ◽  
Light Stimuli ◽  
The Individual

Non-visual photoreceptors (ipRGCs) and rods both exert a strong influence on the human pupil, yet pupil models regularly use cone-derived sensitivity as their basis. This inconsistency is further exacerbated by the fact that circadian effects can modulate the wavelength sensitivity. We assessed the pupillary reaction to narrowband light stimuli in the mesopic range. Pupil size for eighty-three healthy participants with normal color vision was measured in nine experimental protocols with varying series of continuous or discontinuous light stimuli under Ganzfeld conditions, presented after 90 seconds of dark adaptation. One hundred and fifty series of stimulation were conducted across three experiments, and were analyzed for wavelength-dependency on the normalized pupillary constriction (nPC), conditional on experimental settings and individual traits. Traits were surveyed by questionnaire; color vision was tested by Ishihara plates or the Lanthony D15 test. Data were analyzed with generalized additive mixed models (GAMM). The normalized pupillary constriction response is consistent with L+M-cone derived sensitivity when the series of light stimuli is continuous, i.e., is not interrupted by periods of darkness, but not otherwise. The results also show that a mesopic illuminance weighing led to an overall best prediction of pupillary constriction compared to other types of illuminance measures. IpRGC influence on nPC is not readily apparent from the results. When we explored the interaction of chronotype and time of day on the wavelength dependency, differences consistent with ipRGC influence became apparent. The models indicate that subjects of differing chronotype show a heightened or lowered sensitivity to short wavelengths, depending on their time of preference. IpRGC influence is also seen in the post-illumination pupil reflex if the prior light-stimulus duration is one second. However, shorter wavelengths than expected become more important if the light-stimulus duration is fifteen or thirty seconds. The influence of sex on nPC was present, but showed no interaction with wavelength. Our results help to define the conditions, under which the different wavelength sensitivities in the literature hold up for narrowband light settings. The chronotype effect might signify a mechanism for strengthening the individual´s chronotype. It could also be the result of the participant’s prior exposure to light (light history). Our explorative findings for this effect demand replication in a controlled study.

scholarly journals Spectral dependency of the human pupillary light reflex. Influences of pre-adaptation and chronotype.

2021 ◽  
Author(s):  
Johannes Zauner ◽  
Herbert Plischke ◽  
Hans Strasburger
Keyword(s):  
Color Vision ◽  
Stimulus Duration ◽  
Light Stimulus ◽  
Monochromatic Light ◽  
Time Of Day ◽  
Controlled Study ◽  
Pupillary Constriction ◽  
Additive Mixed Models ◽  
Light Stimuli ◽  
The Individual

Non-visual photoreceptors (ipRGCs) and rods both exert a strong influence on the human pupil, yet pupil models regularly use cone-derived sensitivity as their basis. This inconsistency is further exacerbated by the fact that circadian effects can modulate the wavelength sensitivity. We assessed the pupillary reaction to monochromatic light stimuli in the mesopic range. Pupil size for eighty-three healthy participants with normal color vision was measured in nine experimental protocols with varying series of continuous or discontinuous light stimuli under Ganzfeld conditions, presented after 90 seconds of dark adaptation. One hundred and fifty series of stimulation were conducted across three experiments, and were analyzed for wavelength-dependency on the pupillary constriction amplitude (PCA), conditional on experimental settings and individual traits. Traits were surveyed by questionnaire; color vision was tested by  Ishihara plates  or the  Lanthony D15  test. Data were analyzed with generalized additive mixed models (GAMM). The pupillary constriction amplitude response is consistent with L+M-cone derived sensitivity when the series of light stimuli is continuous, i.e., is not interrupted by periods of darkness, but not otherwise. The results also show that a mesopic illuminance weighing led to an overall best prediction of pupillary constriction compared to other types of illuminance measures. IpRGC influence on PCA is not readily apparent from the results. When we explored the interaction of chronotype and time of day on the wavelength dependency, differences consistent with ipRGC influence became apparent. The models indicate that subjects of differing chronotype show a heightened or lowered sensitivity to short wavelengths, depending on their time of preference. IpRGC influence is also seen in the post-illumination pupil reflex if the prior light-stimulus duration is one second. However, shorter wavelengths than expected become more important if the light-stimulus duration is fifteen or thirty seconds. The influence of sex on PCA was present, but showed no interaction with wavelength. Our results help to define the conditions, under which the different wavelength sensitivities in literature hold up for monochromatic light settings. The chronotype effect might signify a mechanism for strengthening the individual´s chronotype, but demands replication in a controlled study.

scholarly journals Do Daily Fluctuations in Psychological and App-Related Variables Predict Engagement With an Alcohol Reduction App? A Series of N-Of-1 Studies (Preprint)

2019 ◽  
Author(s):  
Olga Perski ◽  
Felix Naughton ◽  
Claire Garnett ◽  
Ann Blandford ◽  
Emma Beard ◽  
...  
Keyword(s):  
Mixed Models ◽  
Perceived Usefulness ◽  
Group Level ◽  
Individual Level ◽  
Generalized Additive Mixed Models ◽  
Additive Mixed Models ◽  
The Individual ◽  
Rate Ratios ◽  
Ecological Momentary ◽  
Alcohol Reduction

BACKGROUND Previous studies have identified psychological and smartphone app–related predictors of engagement with alcohol reduction apps at a group level. However, strategies to promote engagement need to be effective at the individual level. Evidence as to whether group-level predictors of engagement are also predictive for individuals is lacking. OBJECTIVE The aim of this study was to examine whether daily fluctuations in (1) the receipt of a reminder, (2) motivation to reduce alcohol, (3) perceived usefulness of the app, (4) alcohol consumption, and (5) perceived lack of time predicted within-person variability in the frequency and amount of engagement with an alcohol reduction app<italic>.</italic> METHODS We conducted a series of observational <italic>N</italic>-of-1 studies. The predictor variables were measured twice daily for 28 days via ecological momentary assessments. The outcome variables were measured through automated recordings of the participants’ app screen views. A total of nine London-based adults who drank alcohol excessively and were willing to set a reduction goal took part. Each participant’s dataset was analyzed separately using generalized additive mixed models to derive incidence rate ratios (IRRs) for the within-person associations of the predictor and outcome variables. Debriefing interviews, analyzed using thematic analysis, were used to contextualize the findings. RESULTS Predictors of the frequency and amount of engagement differed between individuals, and for the variables 'perceived usefulness of the app' and 'perceived lack of time', the direction of associations also differed between individuals. The most consistent predictors of within-person variability in the frequency of engagement were the receipt of a daily reminder (IRR=1.80-3.88; <italic>P</italic>&lt;.05) and perceived usefulness of the app (IRR=0.82-1.42; <italic>P</italic>&lt;.05). The most consistent predictors of within-person variability in the amount of engagement were motivation to reduce alcohol (IRR=1.67-3.45; <italic>P</italic>&lt;.05) and perceived usefulness of the app (IRR=0.52-137.32; <italic>P</italic>&lt;.05). CONCLUSIONS The utility of the selected psychological and app-related variables in predicting the frequency and amount of engagement with an alcohol reduction app differed at the individual level. This highlights that key within-person associations may be masked in group-level designs and suggests that different strategies to promote engagement may be required for different individuals.

scholarly journals Cataract type and pupillary response to blue and white light stimuli

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Manami Kuze ◽  
Kazuno Negishi ◽  
Toshiyuki Koyasu ◽  
Mineo Kondo ◽  
Kazuo Tsubota ◽  
...  
Keyword(s):  
Blue Light ◽  
Stimulus Duration ◽  
White Light ◽  
Light Stimulus ◽  
Pupillary Response ◽  
Ocular Lens ◽  
Light Stimulation ◽  
Significant Difference ◽  
Light Stimuli ◽  
Pupil Reaction

AbstractWe evaluated the pupil reaction to blue and white light stimulation in 70 eyes with cataract and in 38 eyes with a selective blue-light filtering intra-ocular lens. The diameter of the pupil before stimulation was set as baseline (BPD) and, after a stimulus duration of 1 s, the post-illumination pupillary response (PIPR) was measured using an electronic pupillometer. The BPD showed no significant difference among three grades of nuclear sclerosis (NS). In contrast, the PIPRs differed significantly among the NS grades eyes including with and without subcapsular cataract (SC) and IOL eyes for white light (p < 0.05, Kruskal–Wallis test), but not for blue light. Subcapsular opacity did not affect the BPD or PIPR in all cataract grades for either light stimulus. The tendency of larger PIPR in the pseudophakic eyes than the cataract eyes for both lights, however significant difference was found only for white light (p < 0.05 for white light, p > 0.05 for blue light). Our study demonstrates retention of the PIPR for blue light, but not for white light in cataract eyes. We also confirmed that the pupillary response in pseudohakic eyes with a selective blue light-filtering intra ocular lens was greater than that in cataractous eyes for white light.

scholarly journals Do Daily Fluctuations in Psychological and App-Related Variables Predict Engagement With an Alcohol Reduction App? A Series of N-Of-1 Studies

10.2196/14098 ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. e14098 ◽  
Author(s):  
Olga Perski ◽  
Felix Naughton ◽  
Claire Garnett ◽  
Ann Blandford ◽  
Emma Beard ◽  
...  
Keyword(s):  
Mixed Models ◽  
Perceived Usefulness ◽  
Group Level ◽  
Individual Level ◽  
Generalized Additive Mixed Models ◽  
Additive Mixed Models ◽  
The Individual ◽  
Rate Ratios ◽  
Ecological Momentary ◽  
Alcohol Reduction

Background Previous studies have identified psychological and smartphone app–related predictors of engagement with alcohol reduction apps at a group level. However, strategies to promote engagement need to be effective at the individual level. Evidence as to whether group-level predictors of engagement are also predictive for individuals is lacking. Objective The aim of this study was to examine whether daily fluctuations in (1) the receipt of a reminder, (2) motivation to reduce alcohol, (3) perceived usefulness of the app, (4) alcohol consumption, and (5) perceived lack of time predicted within-person variability in the frequency and amount of engagement with an alcohol reduction app. Methods We conducted a series of observational N-of-1 studies. The predictor variables were measured twice daily for 28 days via ecological momentary assessments. The outcome variables were measured through automated recordings of the participants’ app screen views. A total of nine London-based adults who drank alcohol excessively and were willing to set a reduction goal took part. Each participant’s dataset was analyzed separately using generalized additive mixed models to derive incidence rate ratios (IRRs) for the within-person associations of the predictor and outcome variables. Debriefing interviews, analyzed using thematic analysis, were used to contextualize the findings. Results Predictors of the frequency and amount of engagement differed between individuals, and for the variables 'perceived usefulness of the app' and 'perceived lack of time', the direction of associations also differed between individuals. The most consistent predictors of within-person variability in the frequency of engagement were the receipt of a daily reminder (IRR=1.80-3.88; P<.05) and perceived usefulness of the app (IRR=0.82-1.42; P<.05). The most consistent predictors of within-person variability in the amount of engagement were motivation to reduce alcohol (IRR=1.67-3.45; P<.05) and perceived usefulness of the app (IRR=0.52-137.32; P<.05). Conclusions The utility of the selected psychological and app-related variables in predicting the frequency and amount of engagement with an alcohol reduction app differed at the individual level. This highlights that key within-person associations may be masked in group-level designs and suggests that different strategies to promote engagement may be required for different individuals.

scholarly journals Stochastic Properties of Discrete Waves of the Limulus Photoreceptor

1970 ◽  
Vol 56 (6) ◽  
pp. 751-767 ◽  
Author(s):  
Richard Srebro ◽  
Stephen Yeandle
Keyword(s):  
Time Course ◽  
Horseshoe Crab ◽  
Light Stimulus ◽  
Bimodal Distribution ◽  
Latency Distribution ◽  
Time Curve ◽  
Light Stimuli ◽  
The Individual ◽  
Stochastic Properties ◽  
Arbitrary Intensity

In the dark-adapted photoreceptor of the horseshoe crab, Limulus, transient discrete depolarizations of the cell membrane, discrete waves, occur in total darkness and their rate of occurrence is increased by illumination. The individual latencies of the discrete waves evoked by a light stimulus often cannot be resolved because the discrete waves overlap in time. The latency of the first discrete wave that follows a stimulus can be determined with reasonable accuracy. We propose a model which allows us to make an estimate of the distribution of the latencies of the individual light-evoked discrete waves, and to predict the latency distribution of the first discrete wave that follows a stimulus of arbitrary intensity-time course from the latency distribution of the first discrete wave that follows a brief flash of light. For low intensity stimuli, the predictions agree well with the observations. We define a response as the occurrence of one or more discrete waves following a stimulus. The distribution of the peak amplitudes of responses suggests that the peak amplitude of individual discrete waves sometimes has a bimodal distribution. The latencies of the two types of discrete waves, however, follow similar distributions. The area under the voltage-time curve of responses that follow equal energy long (1.25 sec) and short (10 msec) light stimuli follows similar distributions, and this suggests that discrete waves summate linearly.

Spatiotemporal distribution of foraging in a marine predator: behavioural drivers of hotspot formation

2020 ◽  
Vol 635 ◽  
pp. 187-202
Author(s):  
T Brough ◽  
W Rayment ◽  
E Slooten ◽  
S Dawson
Keyword(s):  
Time Of Day ◽  
Spatiotemporal Distribution ◽  
Temporal Effects ◽  
Marine Predator ◽  
Marine Predators ◽  
Additive Mixed Models ◽  
Density Analysis ◽  
The Times ◽  
Passive Acoustic ◽  
Spatial Locations

Many species of marine predators display defined hotspots in their distribution, although the reasons why this happens are not well understood in some species. Understanding whether hotspots are used for certain behaviours provides insights into the importance of these areas for the predators’ ecology and population viability. In this study, we investigated the spatiotemporal distribution of foraging behaviour in Hector’s dolphin Cephalorhynchus hectori, a small, endangered species from New Zealand. Passive acoustic monitoring of foraging ‘buzzes’ was carried out at 4 hotspots and 6 lower-use, ‘reference areas’, chosen randomly based on a previous density analysis of visual sightings. The distribution of buzzes was modelled among spatial locations and on 3 temporal scales (season, time of day, tidal state) with generalised additive mixed models using 82000 h of monitoring data. Foraging rates were significantly influenced by all 3 temporal effects, with substantial variation in the importance and nature of each effect among locations. The complexity of the temporal effects on foraging is likely due to the patchy nature of prey distributions and shows how foraging is highly variable at fine scales. Foraging rates were highest at the hotspots, suggesting that feeding opportunities shape fine-scale distribution in Hector’s dolphin. Foraging can be disrupted by anthropogenic influences. Thus, information from this study can be used to manage threats to this vital behaviour in the locations and at the times where it is most prevalent.

Objective Measurement of Sustained Pupillary Constriction: A Pilot Study Using an App-Based Pupilometer

2020 ◽  
pp. 57-63
Keyword(s):  
Ganglion Cells ◽  
Modern Technology ◽  
Objective Measurement ◽  
Retinal Ganglion ◽  
Case Examples ◽  
Pupillary Reaction ◽  
Sympathetic Nervous Systems ◽  
Pupillary Constriction ◽  
The Individual ◽  
The Right

Background: The pupillary reaction is controlled by the two main branches of the autonomic nervous system, namely the parasympathetic and sympathetic nervous systems. New discoveries in pupil research has identified that intrinsically photosensitive retinal ganglion cells have an impact on pupillary constriction, particularly sustained pupillary constriction. In the current paper, an objective measurement of sustained pupillary constriction versus the inability to maintain sustained pupillary constriction are observed. The variability in the sustained pupillary constriction, i.e. Alpha Omega pupil, can be objectively identified with the use of modern technology. Case Examples: Two female subjects were adapted to dim illumination, and then two objective pupil measurements of the right eye using Reflex – PLR Analyzer by BrightLamp© (Indianapolis, IN, USA) with sustained illumination were obtained. Subject 1, a 25 year-old-female, demonstrated normal ability of the pupil to constrict and sustain constriction for 10 seconds. She was used as a control for subject 2. Subject 2, a 27 year-old-female, demonstrated the inability to sustain pupillary constriction. She reported being under great psychological stress. Her pupil began to re-dilate between 2 and 3 seconds after the initial constriction. Conclusion: Objective pupillometry can be used to assist in many diagnoses and provides the clinician invaluable information on the state of the individual, and qualifications of sustained pupillary constriction can now be assessed in an objective manner.

Effect of interleukin-1 beta on EEG power density during sleep depends on circadian phase

1996 ◽  
Vol 270 (4) ◽  
pp. R830-R837 ◽  
Author(s):  
M. Lancel ◽  
S. Mathias ◽  
J. Faulhaber ◽  
T. Schiffelholz
Keyword(s):  
Power Density ◽  
Interleukin 1 ◽  
Time Of Day ◽  
Controlled Study ◽  
Randomized Experiments ◽  
Eeg Activity ◽  
Circadian Phase ◽  
Activity Phase ◽  
Eeg Power ◽  
A Minor

The cytokine interleukin (IL)-1 is a key mediator of the somnogenic response to immune challenge. In this vehicle-controlled study we evaluated circadian interference with the sleep-promoting effects of IL-1 beta. In two randomized experiments, rats were injected intracerebroventricularly with 5 ng IL-1 beta either at the beginning of the rest phase or at the beginning of the activity phase. Recordings were made during the 24 h preceding the injections (baseline) and during the first 12 postinjection hours. To avoid masking effects of light, the rats were maintained under a skeleton photoperiod during recording. During both the rest and activity phase, IL-1 beta induced fever and initially promoted non-rapid eye movement sleep (REMS). The effect of IL-1 beta on the duration of non-REMS and electroencephalogram (EEG) power densities within non-REMS was related to circadian phase. During the rest phase, IL-1 beta resulted in a minor increase in non-REMS duration but a prominent enhancement in EEG activity in the delta (0.5-4 Hz) and most other frequency bands. During the activity phase, IL-1 beta evoked a larger increase in the duration of non-REMS but hardly affected EEG activity within this state. Thus the effects of IL-1 beta on non-REMS are strongly influenced by diurnal phase. The alterations in EEG power density are in contrast to those elicited by sleep deprivation, which are largely independent of time of day. It is concluded that IL-1 beta activates EEG regulatory mechanisms mediated by processes that depend on circadian phase.

scholarly journals Effectiveness of brushing teeth in patients with reduced oral hygiene by laypeople: a randomized, controlled study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Anna Greta Barbe ◽  
Aya Al-Barwari ◽  
Stefanie Hamacher ◽  
Renate Deinzer ◽  
Ulrike Weik ◽  
...  
Keyword(s):  
Oral Hygiene ◽  
Group Intervention ◽  
Controlled Study ◽  
Care Gap ◽  
Parallel Group ◽  
Dental Professional ◽  
The Individual ◽  
Time Required ◽  
Powered Toothbrush ◽  
Dental Professionals

Abstract Background To evaluate the success of plaque reduction after external toothbrushing by instructed laypeople versus dental professionals using either a manual or powered toothbrush. Longitudinal, randomized, parallel-group intervention study in periodontitis patients with reduced oral hygiene quality undergoing anti-infective therapy. Patients were randomly and equally assigned to one of four groups: laypeople using a manual or powered toothbrush or dental professionals using a manual or powered toothbrush. Plaque reduction (Quigley–Hein-Index (QHI), Marginal Plaque Index (MPI)), gingivitis (papilla bleeding index), and cleaning time (seconds) were investigated. Results Thirty-nine patients participated in the study. Neither the choice of toothbrush (p = 0.399) nor the use of a dental professional (p = 0.790) had a significant influence on plaque levels achieved. However, multivariate modeling indicated statistically significant differences in the external cleaning time between brushing groups, with longer time required by laypeople (p = 0.002) and longer use of the powered toothbrush (p = 0.024). Conclusion When the ability to carry out personal oral hygiene is reduced, external brushing by dental professionals or instructed laypeople who meet previously defined criteria such as sufficient personal oral hygiene at home could help to fill the emerging dental care gap. A combination of oral hygiene approaches adapted to the individual needs of the patients in need of external help is necessary for optimum oral hygiene. Trial registration: German Clinical Trials register (https://www.germanctr.de; number DRKS00018779; date of registration 04/11/2019).

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