Eye Movements Flashcards
What is the main function of eye movements?
to ensure clear, stable vision by keeping visual scene focused on the retina and compensating for changes in head position or environment shifts
What are compensatory eye movements?
Movements that stabilize vision during head or visual field shifts, including VOR (Vestibulo-ocular Reflex) and OKN (Optokinetic Nystagmus)
Why do we study eye movements?
Eye movements provide insights into brain function, as they rely on complex neural circuits and can reveal issues in the brain when abnormal.
What makes eye movements useful for diagnosing brain-related issues?
Abnormal eye movements can signal neurological problems because they involve complex brain systems, making them a valuable tool for detecting conditions like Parkinson’s disease or multiple sclerosis.
What is the difference between accommodative vergence and fusional vergence?
Accommodative vergence: Caused by changes in focus (lens accommodation) when looking at near objects.
Fusional vergence: Caused by binocular disparity, used to align the eyes and maintain single vision when viewing objects at different distances.
How do VOR (Vestibulo-Ocular Reflex) and OKN (Optokinetic Nystagmus) differ in their functions?
VOR: Stabilizes gaze during head movements by moving the eyes in the opposite direction of the head.
OKN: Stabilizes gaze during movement of the visual field (not head movement), causing eye movements that follow the motion of the environment.
What is the role of saccades in targeting eye movements?
Saccades are rapid, voluntary or reflexive eye movements used to redirect the line of sight to a new target.
What is saccadic suppression?
During saccades, visual processing is suppressed to prevent the perception of blur caused by the fast eye movements, ensuring stable vision.
During saccades, visual processing is suppressed to prevent the perception of blur caused by the fast eye movements, ensuring stable vision.
Why is it important for smooth pursuit to only work with predictable and slow-moving objects?
Slow movement allows the eyes to match the velocity of the target, while predictability helps the brain to anticipate and adjust for the target’s motion, ensuring smooth tracking.
Why does OKN involve a combination of smooth pursuit and saccades?
smooth pursuit to follow the motion and saccades to reset the eyes once they reach the edge of the visual field.
Why does OKN involve a combination of smooth pursuit and saccades?
smooth pursuit to follow the motion and saccades to reset the eyes once they reach the edge of the visual field.
How does the brain coordinate eye movements (VOR, smooth pursuit, saccades, OKN) when running and targeting a ball?
the brain prioritizes smooth pursuit and saccade to focus on the ball, while reflexive systems like OKN are suppressed to avoid distraction from the motion of the visual field. VOR plays a complementary role to stabilize your gaze during head movements. This allows you to maintain sharp focus on the ball despite the dynamic environment.
What is the function of VOR?
Compensates for head movement by moving the eyes in the opposite direction to stabilize vision.
What is the stimulus for VOR
signals from the inner ear (vestibular system).
Describe the eye movement in VOR
Eyes move in the opposite direction to head moment
What is the function of OKN
stabilize vision when the visual field moves
What drives OKN ie what results in OKN being activated
Retinal slip: image moves across retina
What are saccades?
Quick, ballistic eye movements that redirect gaze to a new target
What’s the function of Smooth pursuit?
Tracking a slow-moving object
What are the requirements for smooth persuit and why
Slow- so eyes are able to match the objects velocity
Predictable- brain can anticipate the objects position at a given point in time
What stimulates vergence?
Blur or disparity
Which part of the visual pathway is involved in saccadic suppression?
magnocellular pathway at the LGN (lateral geniculate nucleus).
