Eog Flashcards
What is the visual modality in humans?
Among the most important exteroceptive sensory modalities
Where is the density of cones highest in the retina?
In the foveal area
What is the significance of the foveal area?
It is where the highest visual acuity can be achieved
What does the brain attempt to keep on the fovea?
The most salient part of the visual field
How is fixation of an object in the visual field usually accomplished?
By moving the head and/or the eyes
What term describes the movement of the eyes to track objects?
Visual tracking
What are microsaccades?
Minor repetitive, involuntary, quick movements of the eyeball
How can the overall activity of the eye muscles be controlled?
Voluntarily
What are the muscles that move the eyeballs called?
Extrinsic eye muscles
How many extrinsic eye muscles are there?
Six
What is the role of cranial nerve VI?
Innervates the lateral rectus muscle
What does stereo vision require?
Synchronized movements of the two eyeballs
Fill in the blank: The _______ is responsible for the superior oblique muscle.
Trochlear nerve
True or False: The movements of the eyeballs provide the brain with identical images.
False
Which cranial nerve is associated with the oculomotor nerve?
Cranial nerve III
What is the function of the extrinsic eye muscles?
To move the eyeball within the orbit
What is the primary purpose of horizontal and vertical eye movements?
To maintain fixation on an object of interest
What is the primary function of the motor centers located in the frontal lobe of the cortex?
Control of muscles
Includes the remaining four muscles of the eye.
What is the physical structure of the human eyeball described as?
A dipole
Positive terminal in front of the cornea and negative terminal behind the retina.
What potential is generated between the positive and negative terminals of the human eyeball?
Approximately 0.4-1.0 mV
Generated by hyperpolarizations and depolarizations of nerve cells in the retina.
What does electrooculography (EOG) measure?
Movements of the eyeballs as voltage changes
Measured in terms of the potential difference generated by the eyeball’s dipole structure.
How are horizontal movements of the eyeball measured in EOG?
By placing electrode pairs on the temporal side of the two orbits
Vertical movements are measured with electrodes above and below the right eye.
What happens to the EOG signal when the eyeball is in the middle position?
The signal is close to zero
This occurs when the distance from both electrode pairs is equal.
What induces a positive change in voltage in an EOG measurement?
Moving the eyeball horizontally closer to the positive electrode
The opposite movement induces a negative change in voltage.
