Vestibulo Ocular Reflex Mode Biomedelingl.pptx

Modeling and Simulation

1. Vestibulo -Ocular Reflex Model Presented To engr. Abdul Hanan Taqi Presented by M. Faisal Mehmood (2021-bme-102) Husnain ali (2021-bme-103) Ezzat Fatima (2021-bme-126)

2. Objective Observed eye movement during head rotation. Simulated eye movement output generated by the model. In simpler terms, the objective i s to make the model of eye movement .

3. Introduction It’s conjugate ocular movement opposite to head movement and it’s stimulated by vestibular system

4. Cont … VOR is reflex where Activation of vestibular system causes eye movements. This Reflex function stabilize image on retina. During head movements, producing eyes movements in opposite direction to head movement thus persevering (original state) on the central visual field. Vestibular system has sensory system (semicircular canals) which is located in inner layer of ear which can detect the rotational movement. Whenever head move the motion receptors activated and vestibular stimulate the nerves which control extra ocular muscle.

5. Cont …. Semicircular canals act as balance receptors by containing fluid that moves due to head rotation. This movement bends hair cells within the canals, sending signals to the brain about head movement and maintaining balance.

6. The vestibulo -ocular reflex (VOR) uses information from the vestibular labyrinth of the inner ear to generate eye movements that stabilize gaze during head movements. Left Right

7. Cont … Cranial Nerve III, IV and VI involves. CN III called as Oculomotor nerve. CN IV called as Trochlear nerve. CN VI called as Abducens nerve. When head is turned left, both semicircular canals are rotated in opposite rotational direction, which triggers the eyes to move in opposite direction. For left cervical rotation, the right lateral rectus and left medial rectus involve. For right cervical rotation, the left lateral rectus and right medial rectus involve.

8. Example If head is moving right 30 degree so eye should move 30 degree left to focus the image and vice versa.

9. Model Description The vestibulo -ocular reflex (VOR) enables the eyes to move at the same speed and in the opposite direction as the head, so that vision is not blurred when the head moves during normal activity. For example, if the head turns in one direction, the eyes turn in the opposite direction, with the same speed. The file sdoVOR_Data.mat contains uniformly sampled data of stimulation and eye movements. Eye data flipped vertically, would overlay exactly on top of a plot of head motion data. Such a system would be described by a gain of 1 and a phase of 180 degrees. However, when we plot the data in the file sdoVOR_Data.mat , the eye movements are close, but not perfectly compensatory.

10. Output plot The eye movement data does not perfectly overlay the head motion data, and this can be modeled by several factors, like: Neural Processing Delay Gain Measurement noise Non-linearity

11. Parameters There are four parameters in the model:  Delay Gain Tc  Tp. The Delay parameter models the fact that there is some delay in communicating the signals from the inner ear to the brain and the eyes. T his delay is due to the time needed for chemical neurotransmitters to traverse the synaptic clefts between nerve cells.

12. Cont …. The Gain parameter models the fact that the eyes do not move quite as much as the head does. The Tc parameter models the dynamics associated with the semicircular canals, as well as some additional neural processing. T he Tp parameter models the dynamics of the oculomotor plant, i.e. the eye and the muscles and tissues attached to it.

13. Simulink Model

14. Compare Measured Data to Initial Simulated Output

15. Output

16. Sensitivity Analysis

17. Benefits of VOR Model

18. Conclusion The vestibulo -ocular reflex has provided information about the the mechanics and dynamics of how the body maintains visual stability during head movements. Through the systematic modeling of the VOR, using parameters such as Delay, Gain, Tc, and Tp , we have been able to simulate and understand the underlying physiological processes involved in this reflex. Sensitivity analysis showed that Gain and Tp have the most significant influence on the model output, while Delay and Tc have minimal impact. We can fix Delay and Tc during optimization to improve efficiency.

19. References https://www.sciencedirect.com/topics/neuroscience/vestibulo-ocular-reflex# : https://www.mathworks.com/help/sldo/ug/identify-key-parameters-for-estimation-code.html https://youtu.be/r_6y2D-6oDQ?si=4i002BuF_Mc2sbPT https://apsc450computationalneuroscience.wordpress.com/oculomotor-system/