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Results for “Pupil dynamics”

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15 recordsLinked to original sources
PubMed2025

Pupil dynamics in macaque recognition memory tasks: investigating physiological mechanisms.

Cognitive deficits are common in primates, particularly in memory and emotional processes. Rhesus monkey (Macaca mulatta), widely used in cognitive and behavioral research, are central to memory studies. The relationship between recognition memory performance and pupillary dynamics in rhesus monkeys remains underexplored. This study investigated pupil dynamics during recognition memory tasks and their physiological correlates in five sexually mature male rhesus monkeys. We measured pupil diameter and oscillatory features during tasks and analyzed the relationship between behavioral performance and physiological indicators. We found that the average correct response rate exceeded the random success level, and reaction times were significantly shorter during successful recognition than failures, highlighting their cognitive efficiency. During recognition of familiar scenes, average pupil diameter increased, while maximum change in pupil size decreased, indicating reduced cognitive load. Both the frequency and amplitude of pupillary oscillation were lower during successful trials, reflecting decreased cognitive conflict and effective processing. This change reflects a decrease in cognitive conflict and suggests that information processing was more effective. The absolute value of the pupil peak slope decreased during successful recognition, indicating more stable cognitive state. These results support that pupillary dynamics can serve as physiological markers of cognitive effort in rhesus monkeys. Future studies should investigate how stimulus characteristics influence recognition and incorporate measures, such as intracranial EEG and fMRI, to enhance our understanding of their neural mechanisms. This research supports the rhesus monkey model in cognitive neuroscience and contributes to understanding primate cognition and its physiological foundations, with implications for clinical and translational research.

Animals↗
PubMed1977

Neuro-optometry: an evolving specialty clinic.

Neuro-optometry is evolving as an optometric clinical specialty focusing on neurological dysfunctions of the visual system. Initially, we focused upon abnormalities of ocular movements, and our investigations have now broadened to include static and dynamic measurements of eye movements, accommodation, and the pupil. We feel the clinic serves three fundamental purposes: (1) to provide service to the patient, (2) to perform clinical research, and (3) to broaden the scope of the students' clinical experience. Operation of the clinic, technical methods of measurement, the testing protocol, and examples of interesting clinical recordings are described.

Accommodation, Ocular↗
PubMed1978

A study of the hygienic aspects of the pedagogic process.

A knowledge of the laws governing changes in the functional state of the organism of pupils during lessons at school is one of the principal bases for solving the hygienic problems of organizing the teaching. The main concern is the dynamics of changes in the actual functional state of the CNS as a result of a whole complex of endogenous and exogenous factors as well as the school work of the pupil itself. Changes in the functional state of the optic and acoustic analysors deserve special attention in this respect because of their great exposure in pedagogical work. The existing interindividual differences in performance and in the work rate of pupils should be solved by an adequate pedagogical approach. Correct use of the principle of differentiated tuition can be a positive contribution to solving some of the topical problems of hygiene of the pedagogical process.

Acoustic Stimulation↗
PubMed1976

Potentiation of the effects of topical epinephrine on the pupil and intraocular pressure in the sympathetically denervated rabbit eye by a catechol-O-methyl transferase inhibitor.

Dose-response curves of increase in pupil size and decrease in intraocular pressure with topical epinephrine have been determined in the sympathetically denervated rabbit eye. Topical pretreatment with the catechol-O-methyl transferase inhibitor U-0521 potentiated the effects of epinephrine on both the pupil and pressure. These observations suggest a possible role for catechol-O-methyl transferase in the aqueous humor dynamics of the supersensitive eye. The possible use of the denervated rabbit eye as an experimental model for the glaucomatous eye in evaluating the ocular effects of adrenergic agents is discussed.

Administration, Topical↗
PubMed1976

Pharmacokinetics of chlorpromazine-induced miotic response in rabbits.

The time variation of changes in the chlorpromazine-induced pupil diameter decrease was studied following varying bolus and slowly infused intravenous doses administered to rabbits. The observed pharmacological response data were coverted, via, the use of a dose-effect curve, to values theoretically corresponding to relative biophasic drug levels. These values were, in turn, used to construct a linear pharmacokinetic model of the drug bioavailability input equilibrium pharmacological response output dynamics of the system. The use of a time domain, MULTIFIT, computerized method of fitting the data to obtain a pharmacokinetic model was compared to the use of a frequency response, PLTEST, approach. The fidelity of the model in quantitatively relating the time course of systemic drug bioavailability to observed pupil response was verified by the satisfactory agreement obtained by directly comparing experimentally known amounts of drug intravenously infused with corresponding values computed from observed changes in pupil size. The applicability of using pharmacological data for quantitative bioavailability and pharmacokinetic analysis of chlorpromazine is demonstrated. This finding is particularly significant because no suitable chemical or radiological direct assay technique exists for determining levels of chlorpromazine, except for high doses, in body fluids.

Animals↗
PubMed1977

The pupillary, the intraocular pressure and the vasomotor responses to noradrenaline in rabbits.

1. A study has been made of the cause of the temporal disparity between the pupillary and intraocular pressure responses to noradrenaline applied topically. 2. Over a 5-day experimental period, the quantitative characteristics of the pupillary response to noradrenaline applied either once or several times daily remained essentially unchanged. In the same rabbits the delay in pressure response to noradrenaline on the first day was increased by a second application and, on subsequent days, multiple applications of noradrenaline induced a biphasic pressure response. 3. Intravenous phenoxybenzamine inhibited both the pupillary and the biphasic pressure responses to noradrenaline. Phenoxybenzamine applied topically inhibited the ocular hypertensive but not the hypotensive and pupillary responses. 4. Analysis of aqueous humour dynamics by manometric procedures showed that the hyper- and hypotensive responses were associated with increase and decrease, respectively, of the resistance to outflow of the aqueous humour.

Animals↗
PubMed1975

The neuropathological findings in irreversible coma. A critque of the "respirator".

1. Postmortem examinations were made on 240 of the 459 cases succumbing (52 percent of the deaths) in the Collaborative Study on Cerebral Survival; the central nervous system was examined in 226 cases. 2. The autopsy was performed on an average of 15.3 hours after death. 3. The mean weight of the brains was 1450 plus or minus 196 grams; the mean weight of the brains of patients on whom resuscitation was stopped, presumably on the basis of "cerebral death," was greater than that of the patients succumbing to cardiac failure. There was a tendency for the brain to increase in weight about 24 hours after the initiation of resuscitative measures. At that time, swelling, discoloration, softening, congestion, and brain herniations also became more prominent. 4. On the basis of a survey of American neuropathologists and the data from this study, the entity commonly termed "respirator brain" may be confirmed. This is a dynamic process that is complicated by concurrent postmortem changes. The respirator brain requires time (approximately 24 hours) for maturation; many patients die a cardiac death during the metamorphosis. If the patient survives for 3 to 4 days, the percentage dying with typical respirator brains is less, and more patients have electroencephalograms with biological activity. 5. The following clinical factors tend to be associated with an increased number of respirator brains: A. Cerebral trauma B. Subnormal body timperature C. Low systolic blood pressure D. Dilated pupils E. Pupils unresponsive to light F. Absence of cephalic reflexes G. Electrocerebral Silence (ECS) 6. The following factors have no apparent effect on the number of respirator brains or tend to be associated with fewer respirator brains: A. Severe drug intoxications B. Small reacting pupils C. Medications D. Presence of spinal reflexes E. Presence of biological activity (BA) in the electroencephalogram 7. A set of common criteria for a respirator brain was used to test the following: A. The local and consultant neuropathologist's diagnosis of respirator brain B. The significance of critical perfusion pressure and critical oxygen tension in respirator brain C. The role of cardiac output in the production of a respirator brain 8. Since a respirator brain is an imperfectly defined entity, an exact correlation with any combination of clinical and EEG findings could not be expected. The use of a standardized measurement of CBF seems a logical and promising confirmatory test for respirator brain.

Adult↗
PubMed1978

Television pupillometry via digital time processing.

A new modification of the dynamic, infrared recording pupillometer of the closed-circuit television type has been developed, utilizing recent developments in high speed electronic counters. The pupillometer is simple and reliable in operation, has excellent response characteristics, and can be used over a broad range of research and clinical applications.

Animals↗
PubMed1978

Pupillary abnormalities in schizophrenic patients during long-term administration of psychotropic drugs: dissociation between light and near vision reactions.

Pupillographic studies were made of the reactions to light and near vision in 12 schizophrenic patients under long-term administration of psychotropic drugs. The results showed a significant reduction in the light reaction, while the near vision reaction was preserved. The pupillographic study revealed not only reduction in amplitude of the light reaction but also changes in dynamic aspects of the reaction, i.e., prolonged latency time, shortened constriction time, and half redilatation time after the light stimulus. The mechanisms underlying the dissociation between light reaction and near vision reaction induced by long-term administration of psychotropic drugs are obscure, but both the peripheral and central actions of these drugs may be involved.

Adult↗
PubMed1978

Accommodative convergence response to off-foveal retinal images.

A special stimulus device was designed and developed to present blur stimulation through off-foveal retinal images. An infrared reflecting eye movement monitor was used to measure the dynamic accommodative convergence response to both foveal and off-foveal blur stimulation. In most subjects studies a substantial off-foveal accommodative vergence response was found; however, this response diminished rapidly as image distance from the fovea increased. Considerable variation in the response was noted between subjects, and, to a lesser extent, in the same subject for left-versus-right off-foveal image positions.

Adaptation, Ocular↗
PubMed1979

[Time parameters of the retinal control of light intensity and influencing parameters].

The variability of the pupillomotoric control of light intensity was analysed in response to changes in the duration of the light flash, the respiratory phase during stimulation and the age of the subjects. The method of infrared pupillography was used to determine dynamic time parameters. With increasing duration of the light flash from 8 to 125, 250 and 500 ms we observed an acceleration of the latencies whilst the other time parameters were prolonged. There was no significant influence of the time of stimulation during the respiratory cycle. With growing age increased latencies and reduced time parameters of the pupillomotoric transient response were found. The possible reason and importance of the observed changes are discussed.

Adolescent↗
PubMed1979

Changes in pupillary dynamics in young men during prolonged severe exercise.

Infrared pupillography has been performed on 9 male cadets taking part in a combat course lasting for 5 days. The combat course involved lack of sleep, strong physical exercise and caloric deficit. During the course pupillary size was determined after rapid adaptation to darkness and the rate of concentration and the rate of dilatation after stimulation of the opposite eye with light was determined. Dilatation time increased by 50% towards the end of the course and pupillary size before light stimulation was reduced by 14%. On day 3 and 5, but not on day 1, small amplitude pupillary oscillations were observed. The speed of contraction was, however, unchanged.

Adult↗