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Eye (London, England) Aug 2022To evaluate static pupillometric measurements and making inter-ocular comparative analysis in healthy subjects for demonstrating the prevalance of physiological...
BACKGROUND
To evaluate static pupillometric measurements and making inter-ocular comparative analysis in healthy subjects for demonstrating the prevalance of physiological anisocoria in various lighting conditions and to compare the variations of the dynamic pupillometric measurements of the patients with physiological anisocoria.
METHODS
Automatic quantitative pupillometry system was used to measure pupillary diameters in low mesopic (0.1 cd/m), high mesopic (1 cd/m), low photopic (10 cd/m) and high photopic (100 cd/m) conditions. After inter-ocular comparison of these data, the prevalance of physiological anisocoria was detected in four different lighting conditions. The inter-ocular dynamic pupillometric parameters (amplitude, latency, duration and velocity of pupil contraction; latency, duration and velocity of pupil dilation) of these patients were further analysed.
RESULTS
After inter-ocular comparison of pupillary diameters of 195 participants [96 females (49.2%) and 99 males (50.8%)] with a mean age of 38.4 ± 18.9 years (range 7-78 years), six (3.1%) participants under high photopic; 11 (5.6%) participants under low photopic; 25 (12.8%) participants under high mesopic, and 34 (17.4%) participants under low mesopic illumination levels exhibited physiological anisocoria. The mean relative amplitude of anisocoric small pupils' contraction was lower than the mean relative amplitudes of pupil contraction of both isocoric and anisocoric large pupils (p = 0.021, p = 0.035, respectively). The mean velocity of anisocoric small pupils' contraction was lower than the mean velocity of anisocoric large pupils' contraction (p = 0.013).
CONCLUSIONS
The mean contraction amplitude and contraction velocity of smaller pupils was lower when compared to fellow larger pupils of anisocoric patients.
Topics: Adolescent; Adult; Aged; Anisocoria; Child; Female; Humans; Lighting; Male; Middle Aged; Miosis; Photic Stimulation; Pupil; Young Adult
PubMed: 34290440
DOI: 10.1038/s41433-021-01696-7 -
Scientific Reports May 2016Detecting and integrating information across the senses is an advantageous mechanism to efficiently respond to the environment. In this study, a simple auditory-visual...
Detecting and integrating information across the senses is an advantageous mechanism to efficiently respond to the environment. In this study, a simple auditory-visual detection task was employed to test whether pupil dilation, generally associated with successful target detection, could be used as a reliable measure for studying multisensory integration processing in humans. We recorded reaction times and pupil dilation in response to a series of visual and auditory stimuli, which were presented either alone or in combination. The results indicated faster reaction times and larger pupil diameter to the presentation of combined auditory and visual stimuli than the same stimuli when presented in isolation. Moreover, the responses to the multisensory condition exceeded the linear summation of the responses obtained in each unimodal condition. Importantly, faster reaction times corresponded to larger pupil dilation, suggesting that also the latter can be a reliable measure of multisensory processes. This study will serve as a foundation for the investigation of auditory-visual integration in populations where simple reaction times cannot be collected, such as developmental and clinical populations.
Topics: Acoustic Stimulation; Adolescent; Adult; Auditory Perception; Dilatation; Female; Humans; Male; Photic Stimulation; Pupil; Visual Perception; Young Adult
PubMed: 27189316
DOI: 10.1038/srep26188 -
Turkish Journal of Ophthalmology Aug 2023To investigate the effects of pupil diameter on the evaluation of lens and corneal densitometry measured by Scheimpflug tomography.
OBJECTIVES
To investigate the effects of pupil diameter on the evaluation of lens and corneal densitometry measured by Scheimpflug tomography.
MATERIALS AND METHODS
This cross-sectional and comparative study used the right eyes of 32 participants. Corneal and lenticular optical densitometries, corneal volume, anterior segment volume, and anterior chamber depth measurements were taken with the Scheimpflug imaging system when the pupils were mid-dilated and fully dilated. The results were statistically compared.
RESULTS
The mean lens density was 19.20±3.05 when the pupils were mid-dilated (mean pupil diameter 2.98±0.89 mm) and 23.25±3.88 at full dilation (mean pupil diameter 5.01±0.92 mm) (p<0.001). The mean corneal density was 16.15±0.99 with mid-dilated pupils and 16.38±0.95 with fully dilated pupils (p=0.065). Anterior chamber depth and anterior segment volume measurements increased with larger pupil diameter (p<0.05).
CONCLUSION
The lens densitometry values increased with an increase in pupil diameter. The corneal density measurements increased minimally but the differences were not statistically significant. This study revealed that lens densitometry was significantly affected by pupil diameter.
Topics: Humans; Cross-Sectional Studies; Cornea; Pupil; Densitometry
PubMed: 37602578
DOI: 10.4274/tjo.galenos.2022.42724 -
Proceedings. Biological Sciences Sep 2022The locus coeruleus (LC), a nucleus in the pons of the brainstem, plays a significant role in attention and cognitive control. Here, we use an adapted auditory oddball...
The locus coeruleus (LC), a nucleus in the pons of the brainstem, plays a significant role in attention and cognitive control. Here, we use an adapted auditory oddball paradigm and measured the pupil dilation response, to provide a marker of LC activity in humans. In Experiment 1, we show event-related pupil responses to rare auditory events which were further elevated by task relevant. In Experiment 2, by asking participants to silently count the number of oddballs, we demonstrated that the task-relevance elevation was not a result of the generation or execution of the manual response. In Experiment 3, we observed two separate effects of reward on the pupil response. First, we found an overall increase in pupil area in the high compared to the low-reward blocks: a sustained effect reminiscent of the tonic changes that occur in LC. Second, we found elevated event-related pupil responses to behaviourally relevant stimuli in the high-reward condition compared with the low-reward condition, consistent with phasic changes in LC in response to a stimulus. These results highlight the complexity of the relationship between the pupil response and reward, and the inferred role of LC in both top-down and bottom-up cognitive control.
Topics: Attention; Humans; Locus Coeruleus; Pupil; Reward
PubMed: 36100024
DOI: 10.1098/rspb.2022.1545 -
Journal of Neurophysiology Dec 2021Pupil diameter fluctuates in association with changes in brain states induced by the neuromodulator systems. However, it remains unclear how the neuromodulator systems...
Pupil diameter fluctuates in association with changes in brain states induced by the neuromodulator systems. However, it remains unclear how the neuromodulator systems control the activity of the iris sphincter (constrictor) and dilator muscles to change the pupil size. The present study compared temporal patterns of pupil dilation during movement when each muscle was pharmacologically manipulated in the human eye. When the iris sphincter muscle was blocked with tropicamide, the latency of pupil dilation was delayed and the magnitude of pupil dilation was reduced during movement. In contrast, when the iris dilator muscle was continuously stimulated with phenylephrine, the latency and magnitude of rapid pupil dilation did not differ from the untreated control eye, but sustained pupil dilation was reduced until the end of movement. These results suggest that the iris sphincter muscle, which is under the control of the parasympathetic pathway, is quickly modulated by the neuromodulator system and plays a major role in rapid pupil dilation. However, the iris dilator muscle receives signals from the neuromodulator system with a slow latency and is involved in maintaining sustained pupil dilation. By pharmacologically manipulating the pupil dilator and constrictor muscles of human eye separately, we found that the pupil constrictor muscle is a primary controller of rapid pupil dilation upon brain arousal. However, the pupil dilator muscle, which is innervated by the sympathetic nervous system and is generally considered as a major regulator of pupil dilation, is not involved in rapid pupil dilation, but was involved in long-lasting pupil dilation.
Topics: Adult; Arousal; Female; Humans; Male; Muscle, Smooth; Mydriatics; Neural Pathways; Parasympathetic Nervous System; Phenylephrine; Pupil; Tropicamide; Young Adult
PubMed: 34851753
DOI: 10.1152/jn.00401.2021 -
Biological Psychology May 2020Pupil diameter is dynamically modulated by a number of factors, including emotion, motor activity, and attention. Here, pupil modulation was examined as it varies with...
Pupil diameter is dynamically modulated by a number of factors, including emotion, motor activity, and attention. Here, pupil modulation was examined as it varies with locus of control during aversive processing. Participants could control aversive exposure either by escape (terminating the event) or avoidance (blocking the event entirely), or they had no control. Highly anxious (n = 19), moderately anxious (n = 23), and less anxious (n = 23) participants saw cues that signaled whether a fast button press would terminate, prevent, or not affect subsequent presentation of an aversive picture. Pupil diameter was measured throughout the cuing interval. Pupil diameter was larger when preparing to escape or avoid compared to anticipating uncontrollable exposure. All participants, regardless of reported anxiety, showed increased pupil diameter in coping, relative to uncontrollable, contexts. Results support hypotheses that pupil diameter reflects action preparation and that differences in trait anxiety do not modulate this aspect of coping behavior in healthy subjects.
Topics: Adaptation, Psychological; Anxiety; Attention; Cues; Emotions; Female; Humans; Male; Motivation; Pupil; Young Adult
PubMed: 32278595
DOI: 10.1016/j.biopsycho.2020.107885 -
Scientific Reports Dec 2023The alignment between visual pathway signaling and pupil dynamics offers a promising non-invasive method to further illuminate the mechanisms of human color perception....
The alignment between visual pathway signaling and pupil dynamics offers a promising non-invasive method to further illuminate the mechanisms of human color perception. However, only limited research has been done in this area and the effects of healthy aging on pupil responses to the different color components have not been studied yet. Here we aim to address this by modelling the effects of color lightness and chroma (colorfulness) on pupil responses in young and older adults, in a closely controlled passive viewing experiment with 26 broad-spectrum digital color fields. We show that pupil responses to color lightness and chroma are independent from each other in both young and older adults. Pupil responses to color lightness levels are unaffected by healthy aging, when correcting for smaller baseline pupil sizes in older adults. Older adults exhibit weaker pupil responses to chroma increases, predominantly along the Green-Magenta axis, while relatively sparing the Blue-Yellow axis. Our findings complement behavioral studies in providing physiological evidence that colors fade with age, with implications for color-based applications and interventions both in healthy aging and later-life neurodegenerative disorders.
Topics: Humans; Aged; Pupil; Color Perception; Color
PubMed: 38092848
DOI: 10.1038/s41598-023-48513-7 -
Cognition & Emotion Aug 2022Sensitivity to others' emotional signals is an important factor for social interaction. While many studies of emotional reactivity focus on facial emotional expressions,...
Sensitivity to others' emotional signals is an important factor for social interaction. While many studies of emotional reactivity focus on facial emotional expressions, signals such as pupil dilation which can indicate arousal, may also affect observers. For example, observers' pupils dilate when viewing someone with dilated pupils, so-called pupillary contagion. Yet it is unclear how pupil size and emotional expression interact as signals. Further, examining individual differences in emotional reactivity to others can shed light on its mechanisms and potential outcomes. In the current study, adults' ( = 453) pupil size was assessed while they viewed images of the eye region of individuals varying in emotional expression (neutral, happy, sad, fearful, angry) and pupil size (large, medium, small). Participants showed pupillary contagion regardless of the emotional expression. Individual differences in demographics (gender, age, socioeconomic status) and psychosocial factors (anxiety, depression, sleep problems) were also examined, yet the only factor related to pupillary contagion was socioeconomic status, with higher socioeconomic status predicting less pupillary contagion for emotionally-neutral stimuli. The results suggest that while pupillary contagion is a robust phenomenon, it can vary meaningfully across individuals.
Topics: Adult; Arousal; Emotions; Facial Expression; Humans; Individuality; Pupil
PubMed: 35536560
DOI: 10.1080/02699931.2022.2073973 -
Behaviour Research and Therapy Oct 2022Notwithstanding the success of CBT, it is relatively unknown how individuals can better profit from corrective learning experiences. Various theories postulate that...
Notwithstanding the success of CBT, it is relatively unknown how individuals can better profit from corrective learning experiences. Various theories postulate that prediction errors - the difference between what is occurring and what is expected - are the driving force of associative (re)learning. While prediction errors are typically operationalized as violations of cognitive outcome expectancies, direct physiological indices of prediction errors could capture potentially more essential automatic and emotional processes in associative learning. Although physiological responses have previously been suggested to reflect prediction errors, it remains elusive if these measures actually predict changes in subsequent conditioned responding. In three fear-conditioning experiments, we compared pupil dilation and skin conductance responses to unexpected outcomes - unconditioned stimulus (US) presentations or omissions - with expected outcomes, and tested whether outcome responses predicted actual changes in subsequent conditioned responding. We found evidence for increased physiological responses to unexpected outcomes, but the results were inconsistent across experiments. Furthermore, only pupil responses to US presentations consistently predicted an increase in conditioned responding, making it difficult to reconcile our findings with associative learning models. Both pupil dilation and skin conductance can thus index unexpected outcomes, but the relationship of these responses to future learning is not evident and requires further investigation.
Topics: Conditioning, Classical; Emotions; Fear; Galvanic Skin Response; Humans; Learning; Pupil
PubMed: 35994954
DOI: 10.1016/j.brat.2022.104164 -
NeuroImage Dec 2023The size of the eyes' pupils determines how much light enters the eye and also how well this light is focused. Through this route, pupil size shapes the earliest stages...
The size of the eyes' pupils determines how much light enters the eye and also how well this light is focused. Through this route, pupil size shapes the earliest stages of visual processing. Yet causal effects of pupil size on vision are poorly understood and rarely studied. Here we introduce a new way to manipulate pupil size, which relies on activation of intrinsically photosensitive retinal ganglion cells (ipRGCs) to induce sustained pupil constriction. We report the effects of both experimentally induced and spontaneous changes in pupil size on visual processing as measured through EEG. We compare these to the effects of stimulus intensity and covert visual attention, because previous studies have shown that these factors all have comparable effects on some common measures of early visual processing, such as detection performance and steady-state visual evoked potentials; yet it is still unclear whether these are superficial similarities, or rather whether they reflect similar underlying processes. Using a mix of neural-network decoding, ERP analyses, and time-frequency analyses, we find that induced pupil size, spontaneous pupil size, stimulus intensity, and covert visual attention all affect EEG responses, mainly over occipital and parietal electrodes, but-crucially-that they do so in qualitatively different ways. Induced and spontaneous pupil-size changes mainly modulate activity patterns (but not overall power or intertrial coherence) in the high-frequency beta range; this may reflect an effect of pupil size on oculomotor activity and/ or visual processing. In addition, spontaneous (but not induced) pupil size tends to correlate positively with intertrial coherence in the alpha band; this may reflect a non-causal relationship, mediated by arousal. Taken together, our findings suggest that pupil size has qualitatively different effects on visual processing from stimulus intensity and covert visual attention. This shows that pupil size as manipulated through ipRGC activation strongly affects visual processing, and provides concrete starting points for further study of this important yet understudied earliest stage of visual processing.
Topics: Humans; Evoked Potentials, Visual; Visual Perception; Vision, Ocular; Retinal Ganglion Cells; Pupil; Photic Stimulation
PubMed: 37871758
DOI: 10.1016/j.neuroimage.2023.120420