Section 3b: Vestibular and Vision Flashcards
what does the vestibular system do?
detects head acceleration be determining the head movement and position
what components detect what?
otoliths (end organs)
- saccule: linear vertical acceleration
- urticle: linear horizontal acceleration
semicircular canals: angular acceleration
all based on the head
what is roll, pitch & yaw
x, y and z oration axis
how are otoliths and how do they convert head motion to electrical signals
cochlea and by deflection of hairs
describe how the semicircular canals turn signal into angular acceleration
the canals are filled with a thick liquid called endolymph
when the head moves, the endolymph move in that direction (lag) and will push the hairs causing depolarization in one ear and hyperpolarization in another (depending on direction) which signal the motion
what side does the kinocilium face in the right ear
the kinocilium is on the left (like thumb on RIGHT HAND)
what side does the kinocilium face in the left ear
the kinocilium is on the right (like thumb on LEFT HAND)
what causes the kinocilium to cause depolarization
all the hairs falling on it (kinocilium is thumb)
what happens in semicircular canals when I turn my head in one direction (left or right)
the endolymph moves in the opposite direction or the head turn
example: turning left makes the liquid go right
the left ear will start signalling as the hairs as moving right causing depolarization
the right ear will stop signalling as the hairs are turning right causing hyperpolarization
basic way of figuring out which ear will depolarize
direction of head turn causes depilation in that ear
head rate left= left ear depolarize
describe how the otolith signal head acceleration
otolithic stones on top of hairs that move you hairs in the direction your head moves
(forward is depolarization )
what are the 4 functions of the vestibular system
- maintenance of balance
- gaze stabilization: vestibular ocular reflex (VOR)
- perception of self-motion: head motions tells CNS
- spatial navigation/oritenation
what is VOR
vestibular ocular reflex: eyes rotate to maintain target when head moves
what is the galvanic vestibular stimulation?
its when electrodes are placed behind your ears
anodes stimulation: decreased sway
cathode stimulation: increased sway
sway always toward anode (+)
how much refraction occurs at cornea and lens
2/3 cornea and 1/3 lens
what is the fovea?
part of the retina that allows vision of fine details and only contains cones
what pigment does the fovea lay on and why
melanin so it can absorb any light not captured by the photo receptors
what is the vision field
the region of space that can be seen by the full rotation of eyeballs
what are the 2 parts of the vision field?
central and peripheral
what is peripheral vision?
deals where things are
- environmental context and moving limbs
- mostly rods and sparse cones used
what is central vision?
deals with identifying details
- central 5 dares of field
- mostly cones
what is the nasal hemiretina
the retinas on either side of your nose
what is the temporal hemiretina
the retinas by ur ears
what can the left side of the left eyeball see?
right side of the middle view (right nasal vision)
what can the right side of the left eyeball see?
temporal left of left field (left temporal)
what can the left side of the right eyeball see?
temporal right of right field (right temporal)
what can the right side of the right eyeball see?
left of middle view (left nasal)
basic explanation of what the eyes see
the nasal hemiretinas see the temporal side of the opposite side
the temporal hemiretinas see the middle side of the opposite side
how are the optic nerves connected
right side of both eyes report to the right optic nerve
left side of both eyes report to the left optic nerve
what hemiretinas pass the optic chiasm
nasal hemiretinas
what happens if the left optic nerve is cut
whole left eye vision is gone
what happens when the right optic nerve is cut
whole right eye vision gone
what happens when the optic chiasm is cut
middle view is gone (nasal hemiretina)
what happens when the right optic tract is cut
left of middle and left temporal is gone
what happens when the left optic tract is cut
right of middle and right temporal is gone
what is binocular disparity
difference in image location by the left and right sides
what sees close by things
temporal hemiretinas
what sees far things
nasel hemiretinas
what neuron sees just outside and inside the primary visual cortex (V1)
- retinal ganglion (tiny spots of light)
- LGN (lateral geniculate nucleus): tiny spot of light
ENTER VISION CORTEX - Layer C (tiny spot of light)
- simple: lines and edges in particular orientation
- complex lines/edges in a particular orientation any where in receptive field and moving bars of light
receptive fields get more ______ as you go downstream
bigger and complex
what is the optic flow
once processed in V1 it can go MT (middle temporal) then it goes to the medial superior temporal (MST)
what does MT n MST detect
speed of motion and process object and self motion
what is translational flow
integration info for eye to eye
what is rotational flow
motion due to eye movement
2 factors that generate optic flow
speed and direction of eye movement
disttance between eye and points of focus
what does optic flow give you
stability
self velocity and direction
object movement
time to contact
what is time to contact
for intercepting and avoiding things
what is used to calculate time to contact
- optic flow
- binocular disparity
- oculomotor vergence feedback
what part of vision deal with perception
ventral system (primary corex to temporal lobe)
what part of vision deals with action
dorsal (primary vision to parital)
evidence for perception stream
same different discrimination task (ventral)
- look at something and see f they are the same
evidence for action stream
object manipulation (dorsal)
- hold object at stable point
