Research On Vestibular Balance Function Based On Numerical Simulation And Nystagmus Verification

The vestibular semicircular canals in the inner ear can has the function of sensing angular movement of the head,which depends on the biomechanical mechanism of interplay between the endolymph fluid and cupula,and produces involuntary eye movement through the processes of mechano-electrical transduction to maintain the visual stability and body balance.The malfunction of semicircular canals results in vestibular diseases that seriously disrupts the individual’s daily life and work.However,semicircular canals are the complex structure buried deeply in the inner ear,which is difficult to dissect for measurement.The original structure and physical properties of the balance receptors of cupulae in the semicircular canals will be destroy if they are separated from the relevant internal environment,resulting in the functional mechanism of the semicircular canals still remain ambiguous,which seriously hinders the clinical research on the effective treatment for vestibular diseases.To further research the functional mechanism of semicircular canals in this thesis,mechanics and informatics were deeply intersected to fully exhibit the advantages of interdisciplinary.Based on the physiology of vestibule-ocular reflex,a numerical model of vestibular semicircular canals in biomechanics was established,and volunteers’ nystagmus characteristic in rotating chair experiment was obtained by the method of image processing in informatics.The biomechanical responses of cupula in numerical model of semicircular canals and volunteers’ nystagmus characteristic in rotating chair experiment were combined to find their quantitative relationship,which promoted the study of dialectical relationship between the structure and function in semicircular canals,and provided a reliable numerical basis for the clinical research on vestibular balance function and the diagnosis and treatment in vestibular diseases.The innovative work in this thesis includes the following four aspects:(1)Establishment and experimental verification for a numerical model of semicircular canals in human inner ear.Based on a geometrical model of semicircular canals constructed with anatomical parameters of vestibular system in the human inner ear,a numerical model of semicircular canals including structure of crest was established to simulate the biomechanical responses in semicircular canals for sensing angular movement of the head.Besides,a platform of rotating chair experiment was established,and the nystagmus characteristic of volunteers in the experiment were obtained by image processing.According to the principle of vestibuleocular reflex,the biomechanical responses of cupula in numerical model of semicircular canals and volunteers’ nystagmus characteristic in rotating chair experiment were combined to quantitatively analyze the biomechanical mechanism in semicircular canals for sensing angular movement of the head.Meanwhile,the cupula time constant that reflected the dynamic mechanism in the semicircular canals was obtained by numerical model and experiment respectively,which was used to verify the reliability of the numerical model.(2)The quantitative relationship between the biomechanical responses of cupula and volunteers’ nystagmus characteristic was established.Based on the constructed numerical model of semicircular canals,the biomechanical responses in semicircular canals was simulated numerically under different constant angular acceleration.Besides,the volunteers’ nystagmus characteristic under different constant angular acceleration was obtained by rotating chair experiment.Then,the quantitative relationship between the biomechanical responses of cupula and volunteers’ nystagmus characteristic was established,which provided a basical basis for studying the functional mechanism of semicircular canals.(3)The biomechanical responses in semicircular canals and nystagmus characteristic under different spatial orientations were studied.Based on the constructed numerical model of semicircular canals,the biomechanical responses in semicircular canals under different rotation radii were simulated numerically.The volunteers’ nystagmus characteristic under different rotation radii was obtained experimentally.Simultaneously,the biomechanical responses in semicircular canals under different leaning angles of the head were simulated and the nystagmus characteristic at the corresponding head positions was also obtained.From the perspective of biomechanics in semicircular canals,the reasons of the each semicircular canal’s excitation or inhibition under different spatial orientations and the combined effects on the responses of vestibule-ocular reflex in human were theoretically explained,which provided a reliable numerical basis for evaluating clinical function of semicircular canals.(4)Biomechanical responses of cupula in semicircular canals under different temperature and its application on the alleviation of motion sickness were studied.Firstly,volunteers’nystagmus characteristic under different temperature was obtained experimentally.Secondly,the influence of the variation in endolymphatic properties on the biomechanical responses of cupula was excluded by numerical simulation and analysis.According to the effects of reducing temperature on nystagmus characteristic and quantitative relationship between the biomechanical responses of cupula and nystagmus characteristic,it was determined that reducing temperature of semicircular canals could increase the elastic modulus of cupula.Based on this conclusion,it was applied to the alleviation of motion sickness.Finally,volunteers’motion sickness onset time under different temperature in semicircular canals was compared by vehicle experiment,verifying that reducing the temperature of semicircular canals could effectively alleviate motion sickness.