The Vestibular System

Question 1

what is the vestibular system responsible for

Answer 1

balance, spatial orientation, and coordination of movement

Question 2

anatomy of the vestibular system

Answer 2

made up of 2 labyrinths in each inner ear
each of these labyrinths contain 3 semicircular canals and 2 otolith organs

Question 3

what do the semicircular canals do

Answer 3

detect angular acceleration of the head

Question 4

what do the otoliths do

Answer 4

detect linear acceleration of the head

Question 5

what are the 3 semicircular canals called

Answer 5

-anterior/ superior
-posterior
-horizontal/ lateral

Question 6

what are the 2 otolith organs called

Answer 6

-utricle
-saccule

Question 7

vestibular projections

Answer 7

vestibular nerve projects to the vestibular nuclei in the brain stem, as well as the cerebellum
from vestibular nuclei - projects to spinal cord, eye muscles, thalamus and additional cerebellum projections
thalamic vestibular signals go to the cortex and hippocampus

Question 8

where is the vestibular in the cortex

Answer 8

no unimodal vestibular cortical region!
vestibular signals are found throughout the brain
parietal lobe is the main region

Question 9

3 types of vestibular reflexes

Answer 9

-vestibuloocular reflex
-vestibulospinal reflex
-vestibulocollic reflex

Question 10

vestibuloocular reflex

Answer 10

stabilises gaze

Question 11

vestibulospinal reflex

Answer 11

stabilises body posture

Question 12

vestibulocollic reflex

Answer 12

stabilises the head

Question 13

methods to test the vestibular system

Answer 13

-turntables
-caloric vestibular stimulation
-galvaric vestibular stimulation

Question 14

turntables

Answer 14

put pp on a rotating chair
input certain movement path
pre-determined acceleration on a given axis/ plane

Question 15

pros of turntables in researching the vestibular system

Answer 15

-highly controlled
-quite naturalistic

Question 16

cons of turntables in researching the vestibular system

Answer 16

-passive vestibular stimulation - experimenter controls pp movement so not the same as movements in everyday life

Question 17

caloric vestibular stimulation

Answer 17

use of temperature to alter vestibular signals
results in characteristic eye movements
ice water - injected into inner ear canal to change the movement of the fluid inside semicircular ear canal

Question 18

pros of caloric vestibular stimulation

Answer 18

-well controlled
-well regarded

Question 19

cons of caloric vestibular stimulation

Answer 19

-not very precise - onset of timing hard to determine
-short exposure - can’t test pps for minutes or days
-side effects - pps may feel dizzy or sick

Question 20

galvaric vestibular stimulation

Answer 20

electrical currents to stimulate vestibular nerve
positive electrode one side, negative other side
results in a feeling of roll rotation towards the cathode (negative electrode)

Question 21

pros of galvaric vestibular stimulation

Answer 21

-well controlled
-lots of different wave forms - flexible

Question 22

cons of galvaric vestibular stimulation

Answer 22

-not every pp is eligible - you are using electric currents!

Question 23

higher level functions of the vestibular system

Answer 23

-body perception
-self-motion perception
-gravity

Question 24

where do the eyes move during caloric vestibular stimulation

Answer 24

-warm water stimulation = eyes move quickly towards the stimulated ear
-cold water stimulation = eyes move quickly away from the stimulated ear

Question 25

why is it difficult to research the vestibular system

Answer 25

because the vestibular system is 'always on' - we are always receiving vestibular signals so it is hard to test

Question 26

body perception

Answer 26

-body schema: size and shape of the body -body ownership: feeling as if my body belongs to me -self-location: feeling like my body is located in a single place in space

Question 27

gravity

Answer 27

vestibular gravity signals (otoliths) linked to verticality perception (a sense of what is up and down), joint position sense (proprioception) and behavioural control strategies

Question 28

why is the vestibular system involved in body perception

Answer 28

could be because it is to do with gravity detected by otolith organs thus need vestibular input to understand

Question 29

self-motion perception

Answer 29

movement of body through space dependent on a visuo-vestibular integration visuo-vestibular conflicts can lead to motion sickness

Question 30

microgravity

Answer 30

microgravity (e.g. in space) causes 'shutdown' of the vestibular system -early phase: space adaptation syndrome might take a few days to adapt might feel motion sickness -in later phase: adapted to microgravity (although might have problems when returning to normal gravity)

Question 31

clinical factors related to the vestibular system

Answer 31

vestibular conditions typically include vertigo/ dizziness and instability -peripheral conditions -central conditions

Question 32

what are peripheral conditions

Answer 32

involve vestibular nerve and/or labyrinths don't tend to involve brain related vestibular areas vertigo, instability, oscillopsia (shaky vision)

Question 33

examples of peripheral conditions

Answer 33

-BBPV - otoconia in semicircular canals -Menieres Disease - pressure in inner ear -Vestibular neuritis - inflammation of vestibular nerve

Question 34

what are central conditions

Answer 34

central conditions involve structures within the CNS

Question 35

examples of central conditions

Answer 35

-stroke -vestibular migraines

Question 36

vestibular dysfunction

Answer 36

any disruption to vestibular signalling can have profound impacts on the individual, beyond vestibular symptoms -anxiety -depression -memory impairments -depersonalisation/ derealisation -out of body experiences -altered verticality/ motion perception