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MeSH: Pupil-physiology

30 záznamů v Medvik Filtry

Článek

Vliv velikosti zornice na hodnotu subjektivní refrakce

Pivoňková, Bára
Autor Pivoňková, Bára Katedra optometrie a ortoptiky, LF MU v Brně
Vlasák, Ondřej, 1984-
Autor Autorita Katedra optometrie a ortoptiky, LF MU v Brně

Česká oční optika. 2022 ; 2022 (3) : 40-42.

ISSN 1211-233X
Medvik
Zdroj

Článek

Eye pupil - a window into central autonomic regulation via emotional/cognitive processing

Physiological research. 2021 ; 70 (Suppl. 4) : S669-S682. [pub] 20211230

Physiol. Res. (Print)
ISSN 1802-9973
Medvik
Zdroj

If the eyes are windows into the soul, then the pupils represent at least the gateway to the brain and can provide a unique insight into the human mind from several aspects. The changes in the pupil size primarily mediated by different lighting conditions are controlled by the autonomic nervous system regulated predominantly at the subcortical level. Specifically, parasympathetically-linked pupillary constriction is under the Edinger-Westphal nucleus control and sympathetically-mediated pupillary dilation is regulated from the posterior hypothalamic nuclei. However, the changes in the pupil size can be observed at resting state even under constant lighting, these pupillary changes are mediated by global arousal level as well as by various cognitive factors. In this context, autonomic pathways modulating changes in the pupil size in response to the different light levels can be influenced by multiple central descending inputs driving pupillary changes under steady lighting conditions. Moreover, as the pupillary response is involved in emotional (task-evoked pupillary dilation as an index of emotional arousal) and cognitive (task-evoked pupillary dilation as an index of cognitive workload) stimulation, it can be used to detect the impact of mutual subcortical and cortical structures (i.e. overlapping brain structures included in autonomic, emotional and cognitive regulation) on the pupillary innervation system. Thus, complex understanding of the baseline pupil size ́ and pupillary dynamics ́ mechanisms may provide an important insight into the central nervous system functioning pointing to the pupillometry as a promising tool in the clinical application.

MeSH
arousal fyziologie MeSH
autonomní nervový systém fyziologie MeSH
emoce * MeSH
kognice fyziologie MeSH
lidé MeSH
pupila * fyziologie MeSH
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lidé MeSH
Publikační typ
časopisecké články MeSH

Článek

Pupil size variation as a response to stress in European catfish and its application for social stress detection in albino conspecifics

PLoS One. 2020 ; 15 (12) : e0244017. [pub] 20201231

ISSN 1932-6203
Medvik
Zdroj

Hormonal changes such as increased cortisol level in blood plasma in response to stress and social environmental stimuli are common among vertebrates including humans and typically accompanied by other physiological processes, such as changes in body pigmentation and/or pupil dilatation. The role of pupil size variation (PSV) as a response to stress have yet to be investigated in fish. We exposed albino and pigmented European catfish to short-term stress and measured changes in pupil size and cortisol level. Albinos showed lower pupil dilatation and higher cortisol levels than did pigmented conspecifics. A clear positive relationship between pupil dilatation and cortisol concentrations was observed for both pigmented and albino specimens, suggesting that PSV can be used as a stress indicator in fish, irrespective of albino's inability to express social communication by coloring. During the follow-up, we investigated whether a penultimate contest between albino individuals would impact contestants' social stress during subsequent contact. We observed PSV during the contact of unfamiliar albino catfish with different penultimate experiences (winner (W) and/or loser (L)). Then, the following treatment combinations were tested: WW, WL and LL. Twenty-four-hour contact of two unfamiliar catfish resulted in higher pupil dilatation among individuals with previous winner experience. Among treatment combinations, a WL contest displayed the highest pupil dilatation for winners. PSV reflected socially induced stress in individuals that was accompanied by the "winner" experience and dominancy in albinos. To conclude, the present study validates pupil dilatation as a non-invasive method to evaluate stress level in pigmented as well as albino fish in various contexts.

MeSH
hydrokortison krev MeSH
komunikace zvířat * MeSH
pigmentace kůže MeSH
psychický stres krev patofyziologie MeSH
pupila fyziologie MeSH
sumci fyziologie MeSH
zvířata MeSH
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zvířata MeSH
Publikační typ
časopisecké články MeSH
práce podpořená grantem MeSH

Článek

Počtvrté se Speciální olympiádou

Česká oční optika. 2020 ; 61 (1) : 42-43.

ISSN 1211-233X
Medvik
Zdroj

MeSH
diagnostické techniky oftalmologické * normy přístrojové vybavení MeSH
lidé MeSH
nitrooční tlak MeSH
para sportovci MeSH
percepce hloubky fyziologie MeSH
postižení MeSH
pupila fyziologie MeSH
rohovková topografie metody MeSH
testy barvocitu MeSH
zraková ostrost MeSH
zrakové testy metody MeSH
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lidé MeSH

Článek

Pupil size reflects successful encoding and recall of memory in humans

Scientific reports. 2018 ; 8 (1) : 4949. [pub] 20180321

Sci Rep
ISSN 2045-2322
Medvik
Zdroj

Pupil responses are known to indicate brain processes involved in perception, attention and decision-making. They can provide an accessible biomarker of human memory performance and cognitive states in general. Here we investigated changes in the pupil size during encoding and recall of word lists. Consistent patterns in the pupil response were found across and within distinct phases of the free recall task. The pupil was most constricted in the initial fixation phase and was gradually more dilated through the subsequent encoding, distractor and recall phases of the task, as the word items were maintained in memory. Within the final recall phase, retrieving memory for individual words was associated with pupil dilation in absence of visual stimulation. Words that were successfully recalled showed significant differences in pupil response during their encoding compared to those that were forgotten - the pupil was more constricted before and more dilated after the onset of word presentation. Our results suggest pupil size as a potential biomarker for probing and modulation of memory processing.

MeSH
dospělí MeSH
kognice fyziologie MeSH
lidé MeSH
mladý dospělý MeSH
pupila fyziologie MeSH
rozpomínání fyziologie MeSH
světelná stimulace MeSH
velikost orgánu fyziologie MeSH
zdraví dobrovolníci pro lékařské studie MeSH
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dospělí MeSH
lidé MeSH
mladý dospělý MeSH
mužské pohlaví MeSH
ženské pohlaví MeSH
Publikační typ
časopisecké články MeSH
práce podpořená grantem MeSH

Článek

The norepinephrine system and its relevance for multi-component behavior

Neuroimage. 2017 ; 146 (-) : 1062-1070. [pub] 20161005

ISSN 1095-9572
Medvik
Zdroj

The ability to execute several actions in a specific temporal order to achieve an overarching goal, a process often termed action cascading or multi-component behavior, is essential for everyday life requirements. We are only at the beginning to understand the neurobiological mechanisms important for these cognitive processes. However, it is likely that the locus coeruleus-norepinephrine (LC-NE) system may be of importance. In the current study we examine the relevance of the LC-NE system for action cascading processes using a system neurophysiological approach combining high-density EEG recordings and source localization to analyze event-related potentials (ERPs) with recordings of pupil diameter as a proximate of LC-NE system activity. N=25 healthy participants performed an action cascading stop-change paradigm. Integrating ERPs and pupil diameter using Pearson correlations, the results show that the LC-NE system is important for processes related to multi-component behavior. However, the LC-NE system does not seem to be important during the time period of response selection processes during multi-component behavior (reflected in the P3) as well as during perceptual and attentional selection (P1 and N1 ERPs). Rather, it seems that the neurophysiological processes in the fore period of a possibly upcoming imperative stimulus to initiate multi-component behavior are correlated with the LC-NE system. It seems that the LC-NE system facilitates responses to task-relevant processes and supports task-related decision and response selection processes by preparing cognitive control processes in case these are required during multi-component behavior rather than modulating these processes once they are operating.

Článek

The norepinephrine system affects specific neurophysiological subprocesses in the modulation of inhibitory control by working memory demands

Human brain mapping. 2017 ; 38 (1) : 68-81. [pub] 20160813

Hum Brain Mapp
ISSN 1097-0193
Medvik
Zdroj

Inhibitory control processes are known to be modulated by working memory demands. However, the neurobiological mechanisms behind these modulations are inconclusive. One important system to consider in this regard is the locus coeruleus (LC) norepinephrine (NE) system. In the current study the role of the LC-NE system by means of pupil diameter recordings that are integrated with neurophysiological (EEG) and source localization data were examined. A combined mental-rotation Go/Nogo task was used. The results show that increases in working memory load complicate response inhibition processes. On a neurophysiological level these effects were reflected by specific modulations in event-related potentials (ERPs) reflecting motor inhibition processes (i.e., Nogo-P3). Attentional selection processes (reflected by the P1 and N1) as well as pre-motor inhibition or conflict monitoring processes (reflected by the Nogo-N2) were not affected. Activity of the LC-NE systems, as indexed by the pupil diameter data, predicted neurophysiological processes selectively in the Nogo-P3 time range. Source localization analyses suggest that this modulation occurs in the right middle and inferior frontal gyrus. The study provides evidence that the LC-NE system is an important neurobiological system modulating the effects of working memory load on response inhibition processes. More specifically, it modulates a subset of dissociable cognitive processes that are related to prefrontal cortical regions. Hum Brain Mapp 38:68-81, 2017. © 2016 Wiley Periodicals, Inc.

Článek

Chromatic pupillography in hemianopia patients with homonymous visual field defects

Graefe's archive for clinical and experimental ophthalmology. 2017 ; 255 (9) : 1837-1842. [pub] 20170630

Graefes Arch Clin Exp Ophthalmol
ISSN 1435-702X
Medvik
Zdroj

PURPOSE: The pupil light reflex is considered to be a simple subcortical reflex. However, many studies have proven that patients with isolated occipital lesions with homonymous hemianopia show pupillary hemihypokinesia. Our hypothesis is that the afferent pupillary system consists of two pathways: one via intrinsically photosensitive retinal ganglion cells (ipRGCs), the other running through the normal RGCs via the visual cortex. The purpose of this study was to test the hypothesis of these two separate pupillomotor pathways. METHODS: 12 patients (59.1 ± 18.8 years) with homonymous hemianopia due to post-geniculate lesions of the visual pathway and 20 normal controls (58.6 ± 12.9 years) were examined using chromatic pupillography: stimulus intensity was 28 lx corneal illumination, stimulus duration was 4.0 s, and the stimulus wavelengths were 420 ± 20 nm (blue) and 605 ± 20 nm (red), respectively. The examined parameters were baseline pupil diameter, latency, and relative amplitudes (absolute amplitudes compared to baseline), measured at maximal constriction, at 3 s after stimulus onset, at stimulus offset, and at 3 s and 7 s after stimulus offset. RESULTS: The relative amplitudes for the red stimulus were significantly smaller for hemianopia patients compared to the normal controls [maximal constriction: 35.6 ± 5.9% (hemianopia) to 42.3 ± 5.7% (normal); p = 0.004; 3 s after stimulus onset: p = 0.004; stimulus offset: p = 0.001]. No significant differences in any parameter were found between the two groups using the blue stimulus. CONCLUSIONS: The results support the hypothesis that the ipRGC pathway is mainly subcortical, whereas a second, non-ipRGC pathway via the occipital cortex exists.

Článek

Demands on response inhibition processes determine modulations of theta band activity in superior frontal areas and correlations with pupillometry - Implications for the norepinephrine system during inhibitory control

Neuroimage. 2017 ; 157 (-) : 575-585. [pub] 20170621

ISSN 1095-9572
Medvik
Zdroj

Response inhibition processes are important for goal-directed behavior and particularly demanded when it is unlikely to inhibit automatically executed responses. It has been suggested that the norepinephrine (NE) system is important to consider for such likelihood effects. As an indirect measure of the NE system activity we used the pupil diameter and integrated this data with neurophysiological (EEG) data and beamforming analyses. The study shows that inhibitory control processes reflected by theta oscillations are strongly modulated by the likelihood to employ these processes and that these mechanisms were related to neural processes in the SMA and SFG. Probably, the modulations observed for theta band activity may reflect modulations in the encoding of a surprise, or conflict signal. Interestingly, correlation analyses of neuronal activity at the sensor and the source level with pupil diameter data revealed strong correlations that were only seen in the condition where inhibitory control processes were rarely demanded. On the basis of findings and theoretical models suggesting that the pupil diameter can be interpreted as a proximate of NE system activity the results may be interpreted that the NE system modulates inhibitory control processes via theta band activity in the SFB when the likelihood to inhibit a prepotent response tendency is low. From this it may be speculated that the NE system dynamically gains and loses relevance to modulate inhibitory control depending on boundary conditions that determine the mode of responding.