Pupil Dynamics Research Articles

Responses of human visual cortex to uniform surfaces.

Surface perception is fundamental to human vision, yet most studies of visual cortex have focused on the processing of borders. We therefore investigated the responses of human visual cortex to parametric changes in the luminance of uniform surfaces by using functional MRI. Early visual areas V1 and V2/V3 showed strong and reliable increases in signal for both increments and decrements in surface luminance. Responses were significantly larger for decrements than for increments, which was fully accounted for by differences in retinal illumination arising from asymmetric pupil dynamics. Responses to both sustained and transient changes of illumination were transient. Signals in early visual cortex scaled linearly with the magnitude of change in retinal illumination, as did subjects' subjective ratings of the perceived brightness of the stimuli. Our findings show that early visual cortex responds strongly to surfaces and that perception of surface brightness is compatible with brain responses at the earliest cortical stages of processing.

Forecasting Models in the State Education System

This paper presents model-based assessment and forecasting of the Lithuanian education system in the period of 2001-2010. In order to obtain satisfactory forecasting results, constructing of models used for these aims should be grounded on some interactive data mining. Data mining of data stored in the system of the Lithuanian teacher's database and of data from other sources representing the state of education system and the demographic changes in Lithuania was used. The models cover the estimation of data quality in the databases, the analysis of flow of teachers and pupils, the clustering of schools, the model of dynamics of pedagogical staff and pupils, and the quality analysis of teachers. The main results of forecasting and integrated analysis of the Lithuanian teachers' database with other data reflecting the state of the education system and demographic changes in Lithuania are presented.

A Non‐geographical Application of Spatial Information Systems in Pupillometry

AbstractSpatial analysis and spatial information systems have great potential in many non‐geographic domains. This paper presents an example of the utility of spatial analysis in a non‐geographic domain. A technique of pupillometry using digital infrared video loosely coupled with a Spatial Information System and a spreadsheet is developed to accurately quantify pupil dilation magnitude and constriction onset latency for participants of different cognitive ability and under different cognitive loads. Spatio‐temporal pupil dynamics of participants are recorded using digital infrared video. The pupil to iris area ratio is calculated for over 470,000 temporally sequenced de‐interlaced video fields by automatic feature extraction using a combination of threshold analysis, spatial smoothing and areal filtering. Pupil dilation magnitudes and constriction onset latencies are calculated through post‐processing in a spreadsheet. The study identifies inadequacies in current spatial analytical techniques for automatic feature extraction not necessarily evident in geographic applications. Issues impeding the employment of spatial analysis in non‐geographic domains including the lack of a generic spatial referencing system are identified and discussed.

Quantitative Forecasting and Assessment Models in the State Education System

This paper presents model-based forecasting of the Lithuanian education system in the period of 2001–2010. In order to obtain satisfactory forecasting results, development of models used for these aims should be grounded on some interactive data mining. The process of the development is usually accompanied by the formulation of some assumptions to background methods or models. The accessibility and reliability of data sources should be verified. Special data mining of data sources may verify the assumptions. Interactive data mining of the data, stored in the system of the Lithuanian teachers’ database, and that of other sources representing the state of the education system and demographic changes in Lithuania was used. The models cover the estimation of data quality in the databases, analysis of the flow of teachers and pupils, clustering of schools, the model of dynamics of the pedagogical staff and pupils, and the quality analysis of teachers. The main results of forecasting and integrated analysis of the Lithuanian teachers’ database with other data reflecting the state of the education system and demographic changes in Lithuania are presented.

The analysis of the Lithuanian teacher's databases in the scope of mathematics' teaching

In the paper we present the results of integrated analysis of data stored in the system of the Lithuanian teacher's database and of data from other sources representing the state of education system and the demographical changes in Lithuania. The research covers the analysis of dynamics of pedagogical staff and pupils, and the prognosis of tendency that have impact on the development of information society. Special emphasis is placed on teachers of mathematics.

Neurologial Interpretations and the Information in the Cognitive Pupillary Response

It has been known for 70 years that the human pupil dilates when a person responds to a cognitive task. Further, it is known that parasympathetic pupillary innervation decreases with raised attention state while sympathetic innervation increases. But the information the pupil transmits during elevated attention states about such neurological dynamics and a quantitative measure of this information have defied statistical modelling. Now we describe experiments using a short-term memory task called an acoustic impulse test in which the pupillary dynamics in response to random acoustic impulses are recorded with a high resolution (0.01 mm) pupillometer with the result that parasympathetic and sympathetic pupillary dilation components are quantifiable, as is the information transmitted by these components.

Artifact detection and signal reconstruction in the pupillogram

Just as the EEG reflects different wake and sleep stages, changes in pupil dynamics reflecting different levels of vigilance are also to be found. The literature contains numerous reports on experimental set-ups for the recording of the pupillogram. Interesting methods of signal processing are to be found in [7] and [5]. Currently, such recordings are being used to check the success of sleep therapy. A problem that still needs solving is the optimal handling of artifacts caused by blinking. The present article proposes a procedure for artifact detection by back-propagation networks, and subsequent reconstruction of the signal by an AR model. Estimation of the signal is first demonstrated by a test signal, and then by a corrupted pupillogram.

Iris Vascular Changes in Newborns of Diabetic Mothers

Routine ophthalmic examinations of 600 full-term neonates, including 54 born to mothers with insulin-dependent diabetes mellitus and 12 whose mothers had developed gestational diabetes, revealed significant tortuosity and dilatation of the iris vessels in over half of the infants born to diabetic mothers. Ninety percent of the newborns in the diabetic group presented hypoplasia of the iris stroma and pupil dynamics were altered in 85%. The vessel changes resolved spontaneously within 2 weeks after birth. These changes, which have also been observed in cocaine-intoxicated newborns, should raise the suspicion of adverse vascular effects in the fetus caused by maternal diabetes.

精間疲労推定のための瞳孔対光反応の解析

The purpose of this study is to objectively and quantitatively estimate mental fatigue through analysis of pupillary light response with minimum constraint on subjects. Three experiments were performed as follows. First, the effect of retinal dark adaptation on the pupillary dynamics was analyzed. Secondly, pupillary light response and CFF were measured during a two-hour addition task. Thirdly, the relation between mental fatigue and visual organs was investigated. Results were as follows : (i) The magnitude of constriction changes with the retinal adaptation, while, other dynamic characteristics do not. (ii) Mental fatigue caused by the addition task decreases the constriction and dilatation velocities of the pupil. (iii) The changes in the pupillary dynamics in this study can be explained as an elevated state of the parasympathetic nervous system caused by mental workload.

The Effect of Acupuncture on Pupillary Dynamics

The Effect of Acupuncture on Pupillary Dynamics

Infrared pupillometry in the assessment of autonomic function

In order to study normal dynamic pupillary function and to determine reference limits for various pupillary variables, 81 healthy subjects aged between 32 and 60 years were examined using a portable infrared pupillometer. Additionally, 36 patients with type I diabetes mellitus were studied. In healthy subjects, sex had no, or only marginal, effect on the responses. Body mass index or smoking habits had no effect on pupillary dynamics. The relative reflex amplitude (RRA) was independent of age. The time to minimum diameter t min was dependent on maximum constriction velocity (MCV) ( P < 0.001) but not on age, initial diameter or reflex amplitude (RA). The MCV, maximum redilatation velocity (MRV) and time to 75% redilatation ( t 75%) were strongly dependent on RRA ( P < 0.001 for each), but age had no or only a marginal effect. No correlation existed between the results of pupillometry and those of Valsalva or deep breathing tests. The lowest normal value for RRA was 29%. The reference limits for MCV, MRV and t 75% were calculated in relation to RRA. The smaller the RRA was, the slower the velocities and the shorter the t 75% were. Using these reference limits, 25% of the diabetic patients without cardiac autonomic neuropathy and 50% with definite cardiac autonomic neuropathy had abnormalities in at least one out of four pupillary variables. It is concluded that infrared pupillometry may be a useful additional method for the assessment of autonomic function.

Pupillary Dynamics in Down's Syndrome

Pupillary Dynamics in Down's Syndrome

Le constructivisme ne résout pas tous les problèmes

Constructivism cannot solve all the problems , Maria Arcà Silvia Caravita Constructivist theories origin from nineteenth century empirlsm, but the more recent developments derive from genetlcal epistemology and contemporary cognitive science. The underlying model is of a biological type : the organism as an active protagonist constructs and organizes a knowledge which is appropriate for understanding its environment but which does not correspond to the true nature of facts. What problems do emerge when one tries to apply constructivism to school context ? The dynamic of learning processes may differ from the various cognitive dynamics of pupils, and classroom implicite contracts may impede self construction of knowledge at school. However the three key phrases of school constructivism (“children are the authors of their own knowledge", “knowledge is always built on the grounds of previous knowledge", “knowledge is built through conflicts") have deeply Influenced teaching practices. Yet a constructivist renewal of the teaching system could only take place within Institutional structures able to sustain teachers training, to organize hierarchically subjects contents and to evaluate teaching and learning processes.

Pupillographic analysis of visual fatigue caused by VDT work .

The purpose of this study is to objectively and quantitatively estimate the visual fatigue caused by VDT work through analysis of pupillary light response with minimum constraint of subjects. Three experiments were performed as follows. First, the effect of retinal dark adaptation on the pupillary dynamics was analyzed. Secondly, pupillary light response and CFF were measured before and after the VDT task. Thirdly, the relation between visual fatigue and visual organs was investigated. Results were as follows:(i)Such staticcharacteristics of the pupil as an initial diameter change with the retinal adaptation, while, the dynamic characteristics do not.(ii)The adverse effect of VDT work reduces the constriction and dilatation velocities of the pupil.(iii)The changes in the pupillary dynamics are mainly brought about by an elevated state of the parasympathetic nervous system caused by VDT work.

Pupillary dynamics in parkinson's disease

Pupillary dynamics in parkinson's disease

Static and dynamic pupillometry for determination of the course of gradual detoxification of opiate-addicted patients

In order to assess the course of methadone (Heptadone) substitution therapy, 29 inpatients at the Vienna Psychiatric University Clinic (21 males, mean age = 27 years, SD 4 years; 8 females, mean age 29.75 years, SD 5.28 years) who were addicted to opium tea or to a mixture of opium and heroin were investigated by means of computer-assisted "static"- and "light-evoked dynamic" pupillometry. Pupillary measurements were carried out before the start of withdrawal, on the 2nd day 48 h after the administration of 10 mg methadone, and again after the maximum and half of the maximum dose of methadone had been administered. The constricted pupils (the effect of opiate) showed dilatation after the withdrawal syndrome appeared, but immediately after the start of the detoxification treatment, as well as 1 day after administration of the maximum methadone dose a decrease of pupillary diameter was observed. The narrowing of the pupil was followed by an increase in pupillary diameter, which peaked 48 h after the last minimal dose of methadone and nearly reached the normal level. The widening of the pupil reflects an increase of noradrenergic activity under conditions of opiate withdrawal. An increase of spontaneous fluctuations was observed during withdrawal and was only inhibited by the maximum dose of methadone. Finally, pupillary dynamics (shortening of latency time and increase of relative changes) improved during therapy. The pupillary measurement corresponded with clinical observations as well as with self-evaluation during treatment. Thus pupillometry seems to be a useful instrument for assessment of treatment of opiate-addicted patients.

Pupillary dynamics in Parkinson's disease

We reviewed retrospectively 20 cases of optociliary vein over the past 5 years. Fifteen of the 20 cases (75%) were over 40 years of age. There was no sex differences (9 males and 11 females). Causative ocular diseases were: central retinal vein occlusion (14 cases, 70%); optic disc drusen (2 cases, 10%); and optic nerve sheath meningioma, high myopia, glaucoma, congenital anomaly (1 case each, total 20%). The number of patients with an optociliary vein was high in central retinal vein occlusion (14/190 cases, 7.4%). We concluded that occurrence of optociliary vein is not restricted to cases with optic nerve sheath meningioma and this shunt vessel may occur under other conditions in which central retinal venous return is seriously disturbed. The most common cause of optociliary vein is central retinal vein occlusion.

Pupillary dynamics in response to light in neoplastic disease patients

Pupillary dynamics in response to light in neoplastic disease patients

Pupillary changes due to work using visual display terminals

In order to measure the degree of ocular fatigue and general fatigue among the workers using visual display terminal (VDT), pupillary dynamics were measured with open-loop light stimulation for 26 subjects of a mean age of 25.9 years. VDT loads were TV games for 30 min under indirect light of 100 lux. The eight parameters of pupillary light reflex with open-loop pupillometer were examined before and after VDT loads. On the right eyes, two parameters and one value increased 9.2% (Student's t-test: P less than 0.005, max.), 25.7% (Student's t-test: P less than 0.005, Min.) and 14.8% (Student's t-test: P less than 0.005, min/max) just after the load and then gradually decreased and returned to the pre-load level after a 10 to 15-min rest period. Two parameters increased 11.7% (Student's t-test: P less than 0.05, 1/2C) and 12.9% (Student's t-test: P less than 0.05, VD), one parameter decreased -9.0% (Student's t-test: P less than 0.05, 0.63D) and three parameters were constant (Student's t-test: L, A and VC) just after the load. On the left eyes, the same tendencies were observed. But there were no significant differences (Student's t-test) between the right and left eyes. The change pattern of the eight parameters were small in degree and similar to the changes when the sympathetic nervous system was activated.

Pupillary light reflex in patients with hemispheric cerebrovascular disease.

Pupillary dynamics were investigated in 41 patients with hemispheric CVD by means of computerized open-loop videopupillography. The patients were alert and showed either abnormal high- or low-density areas on CT scan. Fourteen cases were examined in the acute stage (within 7 days from onset), 28 cases in the subacute stage (between 8 and 28 days) and 11 cases in the chronic stage (over 29 days). In the acute stage, the parasympathetic nervous functions (maximum velocity and acceleration of pupillary constriction) were hyporeactive and showed no significant differences between the ipsilateral and contralateral side of the lesion. In the subacute stage, these functions were significantly more hyperreactive on the ipsilateral side than on the contralateral side, that is, the parasympathetic functions of the healthy hemisphere became significantly improved in comparison with those in the acute stage. In the chronic stage, no significant differences were observed between the two sides. In contrast, the sympathetic nervous function (maximum velocity of dilatation) showed no differences with respect to either laterality or the time course after onset. The above data suggest that bilateral parasympathetic hypofunctions exist in the acute stage of hemispheric CVD, with an ipsilateral improvement of these functions with the passage of time, and that such autonomic dysfunctions may play some role in the pathophysiology of CVD.