New method of detecting dynamic pupil response (LPR) stimulated by sensory deprivation for assessing the level of activation of the autonomic nervous system (AUN) using rheological models
Studies of reflex regulatory mechanisms in the cardiovascular and respiratory systems are an important element in the development of clinical and experimental diagnostics. Understanding the physiological basis of these mechanisms and the applied methods of performance evaluation is crucial in developing new methods to measure and evaluate the performance of central structures of the Autonomic Nervous System (ANS) influenced by factors such as fatigue, drowsiness, stress. They are also modulated by pathological factors related to hypertension, heart failure or diabetes. All these elements change the ANS activity. In the course of the reflex reaction, the relationship between the sympathetic and parasympathetic parts of the autonomic system changes in favor of one of them. The effects are visible in the effectors located in the cardiovascular system, including the sinus node. This affects the heart rate, iłs inotropism, peripheral resistance.
Most of the literature on fatigue detection and the current psychophysical condition monitored under dynamic conditions clearly focuses on physiological parameters related to the activity of the visual organ itself. The works present descriptions of devices that determine changes in viewing direction, blinking speed and frequency and the actual time of eyeball obscuration by eyelid. Most of these methods have been designed and tested under laboratory conditions and have limited possibilities for use under real conditions.
The purpose of the work is to develop a method for assessing the level of AUN activation based on the assessment of the parameters of the dynamic model describing the pupil reflex and conducting validation tests of the developed method. The method will allow for measurement in a very short time (max. 2 seconds) and the use of rheological models will provide information on the performance characteristics of two systems independently, the sympathetic (SNS) and the parasympathetic (PNS). In the course of the work, two phenomena associated with the eye’s pupil response will be used. The first phenomenon will be reaction of the pupillary on light stimulation (PLR). This reflex is modulated by the accommodation stałe of the eye, and factors of sensory and emotional origin. The effectors are contracting and relaxing iris muscles.
Pupillary unrest index (PUI) is a parameter relating to pupil size instability. It is related to the latter mechanism. Increasing oscillations of pupil movements are the result of decreased activity on the part of sympathetic nervous system (SNS). The main assumption of the project is to confirm, by means of the developed method the possibility of precise and quick identification of changes within ANS on the basis of data from the experiment carried out in conditions of sensory deprivation after long-term use of computer applications in the form of games verified by using VEP (Visual Evoked Potential) and EEG measurement for reference tests. The obtained results will also allow to develop new measurement solutions that could a supplement to indirect and direct methods, i.e. measurements of catecholamines, isotopic methods and microneurography to assess the state of ANS.
As part of the BIOTECHMED-1 Research Grant “Excellence Initiative – Research University” Research Area – Biotechnology and Biomedical Engineering, WUT
Warsaw University of Technology, Centre for Advanced Materials and Technologies CEZAMAT
Central Clinical Hospital of the Ministry of Interior and Administration in Warsaw
Outpatient Clinic and Ophthalmology Hospital “Retina” in Warsaw
200 000 pln
Krzysztof Różanowski PhD Eng.