vastibulo-ocular reflex

[MudPhud20XX]

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Kaplan nueroanatomy has a nice diagram showing how vestibulo-ocular reflex works. So I get that VOR is basically a system that helps our eyes focused during head movement.

So if the head rotates right, then the endolymph flow stimulates hair cells in the right which then stimulates the right oculomotor nucleus and the left abducen nucleus, which help two eye balls look to the left.

Then how does nystagmus play a role in VOR?

Kaplan says nystagmus is rhythmic oscillations of the eyes slowly to one side followed by a rapid reflex movement in the opposite direction. (Nystagmus is defined by the direction of the rapid reflex movement or the fast phase.)

So if I suddenly turn my head to the right, then will the nystagmus occur to the right (fast component) with eyes track (slow component) to the left, correct?

But then, how does exactly nystagmus help us focus during the head movement? All of these concepts were never intuitive to me during my neuro anatomy class. I would appreciate any help.

 

[Miracoli]

Do you think your cerebral cortex will be watching your eyes going the wrong direction? I know you are conscious🙂
You just need cerebral cortex(FEF), PPRF, MLF, CN3, and CN6. Now tell me the patway for the fast response after you turn right?

 

[MudPhud20XX]

Do you think your cerebral cortex will be watching your eyes going the wrong direction? I know you are conscious🙂
You just need cerebral cortex(FEF), PPRF, MLF, CN3, and CN6. Now tell me the patway for the fast response after you turn right?

The fast response would be to the right via the nystagmus governed by the brain stem function, right? But I don't understand how that fast response to the right helps us focus.

 

[ChessMaster3000]

Kaplan nueroanatomy has a nice diagram showing how vestibulo-ocular reflex works. So I get that VOR is basically a system that helps our eyes focused during head movement.

So if the head rotates right, then the endolymph flow stimulates hair cells in the right which then stimulates the right oculomotor nucleus and the left abducen nucleus, which help two eye balls look to the left.

Then how does nystagmus play a role in VOR?

Kaplan says nystagmus is rhythmic oscillations of the eyes slowly to one side followed by a rapid reflex movement in the opposite direction. (Nystagmus is defined by the direction of the rapid reflex movement or the fast phase.)

So if I suddenly turn my head to the right, then will the nystagmus occur to the right (fast component) with eyes track (slow component) to the left, correct?

But then, how does exactly nystagmus help us focus during the head movement? All of these concepts were never intuitive to me during my neuro anatomy class. I would appreciate any help.

I dont think you consciously turning your head to the right constitutes the "fast component" of nystagmus. I'm not sure if nystagmus is technically considered involuntary or not, but you moving your head or your eyes really fast of your own volition is not nystagmus.

 

[Miracoli]

here is the explanation



lesion of the LEFT vestibular labyrinth -->this is seen as if there is stimulation vestibular labyrinth in the right-->increase frequency of APs in the right CN8 and vestibular nucleus-->contraction of RIGHT medial rectus by RIGHT CN3 [ adduct the right eye] and LEFT lateral rectus by LEFT CN6 via MLF[abduct left eye]--> both eyes look to the LEFT(slow component of the nystagmus)
but the cortex realizes the head did not to the right so left frontal eye field(FEF)--> right PPRF-->stimulation of right CN6 and left CN3 via MLF-->both eyes look to the RIGHT(Fast or corrective phase of the nystagmus)