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Charlotte A Hall, Robert P Chilcott
The pupillary light reflex (PLR) describes the constriction and subsequent dilation of the pupil in response to light as a result of the antagonistic actions of the iris sphincter and dilator muscles. Since these muscles are innervated by the parasympathetic and sympathetic nervous systems, respectively, different parameters of the PLR can be used as indicators for either sympathetic or parasympathetic modulation. Thus, the PLR provides an important metric of autonomic nervous system function that has been exploited for a wide range of clinical applications...
March 13, 2018: Diagnostics
João Cavaleiro Rufo, Inês Paciência, Diana Silva, Carla Martins, Joana Madureira, Eduardo de Oliveira Fernandes, Patrícia Padrão, Pedro Moreira, Luís Delgado, André Moreira
BACKGROUND: Endurance swimming exercises coupled to disinfection by-products exposure has been associated with increased airways dysfunction and neurogenic inflammation in elite swimmers. However, the impact of swimming pool exposure at a recreational level on autonomic activity has never been explored. Therefore, this study aimed to investigate how swimming pool attendance is influencing lung and autonomic function in school-aged children. METHODS: A total of 858 children enrolled a cross sectional survey...
2018: PloS One
Vinayak Narayan, Nasser Mohammed, Amey R Savardekar, Devi Prasad Patra, Christina Notarianni, Anil Nanda
BACKGROUND: Traumatic brain injury [TBI] is a leading cause of pediatric morbidity and mortality worldwide and intracranial pressure [ICP] monitoring plays a crucial role in its management. Based on existing literature, the authors review the current practicing non-invasive ICP monitoring devices and their accuracy in predicting raised ICP in pediatric TBI. MATERIALS AND METHODS: A thorough literature search was conducted on PubMed, Medline and Cochrane data base, articles were selected systematically, reviewed completely and relevant data was summarized and discussed...
March 7, 2018: World Neurosurgery
Naresh Mullaguri, Nakul Katyal, Aarti Sarwal, Jonathan M Beary, Pravin George, Naresh Karthikeyan, Premkumar Nattanamai, Christopher R Newey
Although a neurological examination is fundamental to the evaluation of comatose patients, it is less reliable in a medically induced coma. A commonly misinterpreted finding in patients in a pentobarbital coma is altered pupillary reactivity secondary to an exaggerated ciliospinal reflex. Recognizing an exaggerated ciliospinal reflex in patients in a pentobarbital coma is important and may prevent unnecessary intervention. We present a patient induced in a pentobarbital coma for the treatment of status epilepticus who exhibited a nonreactive pupil secondary to an exaggerated ciliospinal reflex confirmed by pupillometry...
December 30, 2017: Curēus
Marco Turi, David Charles Burr, Paola Binda
The pupil is primarily regulated by prevailing light levels but is also modulated by perceptual and attentional factors. We measured pupil-size in typical adult humans viewing a bistable-rotating cylinder, constructed so the luminance of the front surface changes with perceived direction of rotation. In some participants, pupil diameter oscillated in phase with the ambiguous perception, more dilated when the black surface was in front. Importantly, the magnitude of oscillation predicts autistic traits of participants, assessed by the Autism-Spectrum Quotient AQ...
March 6, 2018: ELife
Tsukasa Satou, Sayaka Kato, Akihito Igarashi, Misae Ito, Shuntaro Tsunehiro, Manabu Koshimizu, Takahiro Niida, Kimiya Shimizu
PURPOSE: Pupillometry should be performed under conditions as close to natural viewing as possible. The present study aimed to determine whether pupil size in binocular open-view settings can be predicted based on pupil size measured using the CASIA2 device. METHODS: The present study included 61 participants (25 men and 36 women; mean age, 49 ± 15 years; age range, 22-69 years) with no history of ophthalmic disease other than refractive errors and cataract...
March 2, 2018: International Ophthalmology
Dorothea Hämmerer, Martina F Callaghan, Alexandra Hopkins, Julian Kosciessa, Matthew Betts, Arturo Cardenas-Blanco, Martin Kanowski, Nikolaus Weiskopf, Peter Dayan, Raymond J Dolan, Emrah Düzel
The locus coeruleus (LC) is the principal origin of noradrenaline in the brain. LC integrity varies considerably across healthy older individuals, and is suggested to contribute to altered cognitive functions in aging. Here we test this hypothesis using an incidental memory task that is known to be susceptible to noradrenergic modulation. We used MRI neuromelanin (NM) imaging to assess LC structural integrity and pupillometry as a putative index of LC activation in both younger and older adults. We show that older adults with reduced structural LC integrity show poorer subsequent memory...
February 12, 2018: Proceedings of the National Academy of Sciences of the United States of America
Pauline van der Wel, Henk van Steenbergen
Pupillometry research has experienced an enormous revival in the last two decades. Here we briefly review the surge of recent studies on task-evoked pupil dilation in the context of cognitive control tasks with the primary aim being to evaluate the feasibility of using pupil dilation as an index of effort exertion, rather than task demand or difficulty. Our review shows that across the three cognitive control domains of updating, switching, and inhibition, increases in task demands typically leads to increases in pupil dilation...
February 12, 2018: Psychonomic Bulletin & Review
Olga I Rozanova, Andrey G Shchuko, Tatyana S Mischenko
Background: The accommodation has considerable interactions with the pupil response, vergence response and binocularity. The transformation of visual reception processing and the changes of the binocular cooperation during the presbyopia development are still poorly studied. So, the regularities of visual system violation in the presbyopia formation need to be characterized. This study aims to reveal the transformation of visual reception processing and to determine the role of disturbances in binocular interactions in presbyopia formation...
2018: Eye and Vision (London, England)
Tomaž Čegovnik, Kristina Stojmenova, Grega Jakus, Jaka Sodnik
This paper presents a driving simulator study in which we investigated whether the Eye Tribe eye tracker (ET) is capable of assessing changes in the cognitive load of drivers through oculography and pupillometry. In the study, participants were asked to drive a simulated vehicle and simultaneously perform a set of secondary tasks with different cognitive complexity levels. We measured changes in eye properties, such as the pupil size, blink rate and fixation time. We also performed a measurement with a Detection Response Task (DRT) to validate the results and to prove a steady increase of cognitive load with increasing secondary task difficulty...
April 2018: Applied Ergonomics
João Costa, André Moreira, Pedro Moreira, Luís Delgado, Diana Silva
BACKGROUND: Obesity has been linked to autonomic dysfunction, which is thought to be one of the main contributors for hypertension, cardiac remodelling and death. Exercise and diet-based weight loss are the mainstay therapy for obesity, but there is a paucity of data regarding the effect of weight changes in autonomic nervous system (ANS) activity. OBJECTIVE: To describe the impact of weight changes in autonomic nervous system. METHODS: A systematic literature search of four biomedical databases was performed evaluating effects of weight changes, thorough diet and/or exercise-based interventions, in the following ANS outcomes: heart rate variability, namely low frequency (LF)/high frequency (HF) ratio (LF/HF ratio), normalized units of LF (LFnu) and HF (HFnu), muscle sympathetic nerve activity (MSNA), noradrenaline spillover rate (NA-SR), standard deviation of normal-to-normal intervals (SDNN), root mean square of successive differences (RMSSD), baroreflex sensitivity and pupillometry...
January 9, 2018: Clinical Nutrition: Official Journal of the European Society of Parenteral and Enteral Nutrition
John A Emelifeonwu, Kirsten Reid, Jonathan Kj Rhodes, Lynn Myles
There is good evidence that pupil reactivity is useful for prognostication in acute head injuries. Despite this, most pupil assessments are subjective and are performed by physicians who may not be experts. They can therefore be unreliable. We present a case of a patient with seemingly irreversible demise from an acute traumatic subdural haematoma. This was determined by assessment of his pupils, which were non-reactive to light at the time of arrival to the neurosurgical theatre. He was transferred to the neurointensive care for brainstem death testing, where assessment by objective pupillometry determined that his pupils were in fact reactive...
February 1, 2018: Brain Injury: [BI]
Miriam Schwalm, Eduardo Rosales Jubal
The mammalian thalamocortical system generates intrinsic activity reflecting different states of excitability, arising from changes in the membrane potentials of underlying neuronal networks. Fluctuations between these states occur spontaneously, regularly, and frequently throughout awake periods and influence stimulus encoding, information processing, and neuronal and behavioral responses. Changes of pupil size have recently been identified as a reliable marker of underlying neuronal membrane potential and thus can encode associated network state changes in rodent cortex...
November 2017: ENeuro
Özge Yüzgeç, Mario Prsa, Robert Zimmermann, Daniel Huber
During wakefulness, pupil diameter can reflect changes in attention, vigilance, and cortical states. How pupil size relates to cortical activity during sleep, however, remains unknown. Pupillometry during natural sleep is inherently challenging since the eyelids are usually closed. Here, we present a novel head-fixed sleep paradigm in combination with infrared back-illumination pupillometry (iBip) allowing robust tracking of pupil diameter in sleeping mice. We found that pupil size can be used as a reliable indicator of sleep states and that cortical activity becomes tightly coupled to pupil size fluctuations during non-rapid eye movement (NREM) sleep...
January 11, 2018: Current Biology: CB
Kemal Tekin, Mehmet Ali Sekeroglu, Hasan Kiziltoprak, Sibel Doguizi, Merve Inanc, Pelin Yilmazbas
BACKGROUND: This study sought to determine normative static and dynamic pupillometry data in different age groups in a healthy population, and to investigate the effects of age on pupillometric characteristics. METHODS: Pupillometry measurements were undertaken on 155 healthy participants using an automatic quantitative pupillometry system. Static pupillometry measurements were undertaken; these included scotopic pupil diameter (PD), mesopic PD, low photopic PD and high photopic PD values...
January 21, 2018: Clinical & Experimental Optometry: Journal of the Australian Optometrical Association
Ronen Hershman, Avishai Henik, Noga Cohen
Pupillometry (or the measurement of pupil size) is commonly used as an index of cognitive load and arousal. Pupil size data are recorded using eyetracking devices that provide an output containing pupil size at various points in time. During blinks the eyetracking device loses track of the pupil, resulting in missing values in the output file. The missing-sample time window is preceded and followed by a sharp change in the recorded pupil size, due to the opening and closing of the eyelids. This eyelid signal can create artificial effects if it is not removed from the data...
January 16, 2018: Behavior Research Methods
Sanket S Shah, Sudhi P Kurup, Hantamalala Ralay Ranaivo, Rebecca B Mets-Halgrimson, Marilyn B Mets
BACKGROUND: Marfan syndrome (MFS) is a genetic disorder that affects multiple organ systems, including the eye. The most common ocular manifestations include ectopia lentis and retinal detachment. The current literature qualitatively cites that MFS patients have miotic or "poorly dilating" pupils. This study was the first to quantitatively assess pupillary function in MFS patients. MATERIALS AND METHODS: 57 eyes from 29 MFS patients, 36 eyes from 18 pediatric age- and gender-matched controls, and 44 eyes from 22 adult age-matched controls were measured in a clinic-based cross sectional study...
January 16, 2018: Ophthalmic Genetics
Sebastiaan Mathôt, Jasper Fabius, Elle Van Heusden, Stefan Van der Stigchel
Measurement of pupil size (pupillometry) has recently gained renewed interest from psychologists, but there is little agreement on how pupil-size data is best analyzed. Here we focus on one aspect of pupillometric analyses: baseline correction, i.e., analyzing changes in pupil size relative to a baseline period. Baseline correction is useful in experiments that investigate the effect of some experimental manipulation on pupil size. In such experiments, baseline correction improves statistical power by taking into account random fluctuations in pupil size over time...
January 12, 2018: Behavior Research Methods
Alexander Papangelou, Elizabeth K Zink, Wan-Tsu W Chang, Anthony Frattalone, Daniel Gergen, Allan Gottschalk, Romergryko G Geocadin
Introduction: Transtentorial herniation (TTH) is a life-threatening neurologic condition that typically results from expansion of supratentorial mass lesions. A change in bedside pupillary examination is central to the clinical diagnosis of TTH. Materials and. Methods: To quantify the changes in the pupillary examination that precede and accompany TTH and its treatment, we evaluated 12 episodes of herniation in three patients with supratentorial mass lesions using automated pupillometry (NeurOptics, Inc...
January 1, 2018: Military Medicine
Vladislav Ayzenberg, Meghan R Hickey, Stella F Lourenco
An unusual, but common, aversion to images with clusters of holes is known as trypophobia. Recent research suggests that trypophobic reactions are caused by visual spectral properties also present in aversive images of evolutionary threatening animals (e.g., snakes and spiders). However, despite similar spectral properties, it remains unknown whether there is a shared emotional response to holes and threatening animals. Whereas snakes and spiders are known to elicit a fear reaction, associated with the sympathetic nervous system, anecdotal reports from self-described trypophobes suggest reactions more consistent with disgust, which is associated with activation of the parasympathetic nervous system...
2018: PeerJ
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