Vestibular System Flashcards
the vestibular system can be considered our sense of _________
equilibrium; keeping yourself stable despite world around you
4 things involved in the vestibular system
spatial orientation
vestibulo-ocular reflex
balance
vestibulo-autonomic reflexes
in the vestibular system, you are constantly …
adjusting your position yet you always feel stable
issues tied to vestibular system
spatial disorientation
- any impairment of spatial orientation
dizziness
- nonspecific spatial disorientation
vertigo
- a sensation of rotation or spinning
imbalance
blurred vision
illusory self-motion
spatial orientation
perception of angular motion, linear motion, and overall tilt
examples:
- angular: rotation of head from side to side
- linear: your bus slams on the breaks
- tilt: your orientation with respect to gravity
balance
processes of postural control by weight distribution, allowing us to stay upright and stable
vestibulo-ocular reflex
the countermovement of your eyes in response to a head movement in order to maintain stable fixation
- shaking finger = blur, shaking head = still finger
vestibulo-autonomic responses
vestibular system communicates with autonomic system like blood pressure, gastrointestinal, etc. about equilibrium
- things like motion sickness tied to this, and control of blood flow when standing vs. laying
sense of equilibrium is ______
active
afferent and example
external inputs about the world
world info going to brain
ex. graviception, vestibular system is how your body seemingly automatically understands gravity
efferent
inputs about muscle movements
info exiting brain going to muscles, guiding movement
semicircular canals
3 of them!
toroidal (donut like) tubes that sense changes in angular velocity/acceleration
otolith organs
2 of them!
mechanical structures that sense linear acceleration and gravity
when talking about vestibular sensing we’ll talk about 3 directional planes:
x (forward and back)
y (left/right)
z (up/down)
orientation is relative to your ____
head
linear motion can be represented in terms of … while angular motion can be represented as …
change along x, y, z; rotation along x, y, z
roll vs. pitch vs. yaw
roll: rotation on x-axis
pitch: rotation on y-axis
yaw: rotation on z-axis
moving at a constant velocity does not produce response in the ______ ________
vestibular organs
part of why you don’t feel like you’re moving in your car or the earth spinning
how do we transduce “equilibrium”?
hair cells and mechanoreception
2 difference between vestibular hair cells and auditory hair cells?
vestibular is based on head movement instead of sound vibration
vestibular hair cells release a baseline constant amount of neurotransmitter at “rest”
bending the stereocilia in vestibular hair cells can result in … based on the direction (what direction?)
depolarization (left/towards kinocilium) or hyperpolarization (right/towards shortest stereocilia)
any hair cell can code a particular set of ______/_______
directions/rotations
kinocilium
largest stereocilia
bony labyrinth
each is ~3/4 of a toroid shape (donut) filled perilymph fluid
bony exterior to keep in place
membranous labyrinth
inside bony labyrinth, separated by the perilymph is a smaller, membrane toroid filled with endolymph fluid
jelly/membrane interior, change info for how fluid presses against hair cells
the bony and membranous canals/labyrinths meet at a chamber called the
vestibule
semicircular canals run ______ to each other
perpendicular
horizontal semicircular canal rotates on __-axis (and term)
z; yaw
anterior and posterior semicircular canal rotates on both __-axis’ (and term)
x+y; roll+pitch
ampulla
contain the structures that allow for transduction
where semicircular canals swell into
features inside the ampulla
crista
- ~7000 hair cells are anchored and connected to nerve fibers
cupula
- a jelly-like, elastic dam into which stereocilia project
hair cells in each ampulla are arranged in the same direction with respect to their
kinocilium
as you rotate tour head, endolymph movement lags due to _____
inertia
the endolymph presses in the _____ direction on the cupula, deflecting the ________ of the hair cells
opposite; stereocilia
your two ears respond in _________ fashions in relation to the endolymph movement; meaning when one side is depolarized, the other is _________
complementary; hyperpolarized
opposing posterior/anterior canals have _____ planes, so the push/pull complementary nature is between posterior/anterior from opposite ears (what does this mean)
parallel; one sides anterior is opposite of the other sides posterior canal
since afferent are firing steadily, the can code …
both decreases and increases in angular acceleration and amount is based on how deflected the hair cells become
why do we use sine waves to measure back and forth movements of the head?
many movements return to baseline and you can also deconstruct complex movements into simple sine waves
2 organs that sense acceleration and tilt (overall term for them both then individual names and differences)
otolith organs
- utricle: 30,000 hair cells
- saccule: 16,000 hair cells
macula
“spot”
present on both otolith organs, specialized to detect linear acceleration and gravity/detect shear forces
the macula are planar, so the utricle macula is ______ while the saccular macula is ______
horizontal; vertical
striola
hair cells aligned relative to a midline structure in the macula
otoconia
ear stones present on top of stereocilia in macula
exacerbate the inertia of the gel membrane and also weigh it down relative to gravity
______ accelerations move otoconia more; meaning that change in receptor’s potential is _______ to the magnitude of that movement
large; proportional
3 ways to test vestibular perception
threshold estimation
- what is the minimum motion needed to correctly perceive motion direction
magnitude estimation
- participants report how much they think they tilted, rotated, or translated
matching
- participants are tilted and then orient a line with the direction of gravity. done in a dark room with only the line visible to avoid any visual cues
velocity storage
perception of “stop” lags behind the time course of the neurons’ habituation
when reproducing translations, the vestibular system is not only good at producing ______, but also _____
direction; velocity
vestibular system detects velocity by doing ________ ________
mathematical integration
which part of the vestibular system physically causes hair cells to bend in response to fluid inertia from angular motion?
a. cupula
b. saccule
c. utricle
d. ampulla
cupula
do you know what angular rotation and tilt looks like on graphs?
yes, on slide 6 for touch presentation
is there a vestibular cortex?
nope
vestibulo-spinal responses
a set of reflexes that help you almost automatically adjust your body as you transfer weight
vestibular organs project to the _______ _____ in the brain stem
vestibular nuclei
the vestibular nuclei project to _______ where it is integrated with muscle/skin input and from there, goes to multiple cortical regions, many of which also receive visual input –> _______ ______
thalamus; multisensory integration
multisensory integration
vestibular inputs combined at multiple points with other senses
vection
anything that gives you a sense of motion/physical movement/rotation despite not moving at all
ex. being on a boat all day and then stepping off but still feeling as though you are on a boat
