KNES 365 midterm 2

What is gaze movement

Sum of eye and head movement

What contains hair cells

Cupula in ampulla in each SC canals

When are each canals activated

Rotation around: vertical axis: horizontal canals

Ear to ear: ant and post

Front to back: ant and post

What happens when the head moves at constant speed

Endolymph moves at the same speed as the head and doesn’t move the cupula

What is otoconia

Chalk crystals on top of otolithic membrane

What is striola

Separates top and bottom hair cells which detect movement in opposite directions

What does utricle and saccule contain

Otolith organs which detect linear motion

What does tilting the head and holding the head do to otolith organ firing

It continues to fire unlike hair cells in the ampulla which stop firing if head moves at constant speed

What does parietoinsular vestibular cortex(PIVC) do

Integrates vestibular, optic flow, and somatosensory information for proprioception and coordinating movement

What info does 3a and 2v areas of the brain process

Head and neck somatosensory information

CNIV, CN VI, CN III nerve

CN IV = trochlear nerve(controls sup obl muscle)

CN VI = Abducens nerve(Lat rect)

CN III = Oculomotor nerve (the rest of muscles)

What is Nystagmus

For example, when head turns to the right, VOR moves eyes to the left at the speed at which the head turns.

But when the eye reaches its physical limit due to continuous head movement, the eyes saccade quickly to start tracking a new point.

What is Vestibular Head impulse test (VHIT) and catch up saccades

Turning head rapidly to one side to test VOR and catch up saccades occur when eye moves in the same direction as the head turning and has to execute catch up saccades to properly track the target

What is the caloric vestibular testing

Warm water on one side and cold water on the other side, creates a sensation that head is turning and VOR responds to move the eye. It stimulates horizontal SC canals

What is rotational/translational vestibular testing

Done on robotic chair that rotates in darkness and you must determine which way you’re turning. Every hair is covered with clothing to ensure they’re almost only using vestibular system

What reflex pathway does electrical vestibular stimulation effect and what is electrical vestibular stimulation

Vestibulo-spinal pathway and it makes the person sway to the side with positive electrode as a corrective movement

COG, BOS, COP

COG: centre of gravity. COP: sum of ground reaction force

What does the romberg test test

Postural stability

What is bi-pedal walking

Feet moves in antiphase, swing and stance. Always at least one foot is in contact with the ground, and sometimes both feet are touching the ground.

What is bi-pedal running

Never both feet touch ground at the same time, there are times where neither is touching. Swing is longer than stance.

Does medial and lateral vestibular nucleus control muscles bilaterally or ipsilaterally

Medial is bilateral, lateral is ipsi

What is the vestibular-cerebellar pathway

Vestibular nucleus send info to cerebellum, cerebellum sends signal back to the nucleus based on somatosensory information. It also helps distinguish self motion vs impact

At rest, is there current flowing through hair cells.

yes, stretch gated K+ ions are open

Compared to at rest, when hair cells are deflected against their prefered direction, is the firing rate higher or lower

it is lower

Utricle and saccule, which is responsible for horizontal and for vertical

horizontal: utricle

vertical: saccule

What ions enter CGMP gated ion receptors in photoreceptors

Ca++ and Na+

Explain the steps through which CGMP gated channels open and close

Photon interacts with retinal opsin molecules, changing its physical shape.

This leads to a cascade of reactions and activates PDE which breaks down CGMP.

Explain parvo and magnocellular receptive fields

multiple rods connect to a single bipolar: magno

One cone connects to a single bipolar: parvo

What kind of receptor is off centre bipolar cell

mGluR6 receptor