Sensory Components Of Motor Control Part 2 Flashcards
Vestibular system
Sensory system responsible for providing brain with info about motion, head position and spatial orientation involved with motor functions
What does the vestibular allow us to do
Keep balance
Stabilize head and body during movement
Maintain posture
3 parts of vestibular structure
Otoliths (utriculus and sacculus)
3 semi-circular canals
Otoliths
Stones or crystals that detect linear acceleration, head tilt and gravity
2 type of otoliths
- Utriculus (anterior-posterior motion)
- speed up slow down in car - Sacculus (vertical movement)
- elevator
3 semicircular canals
Detect angular (rotational) acceleration
- anterior, posterior, horizontal/lateral
What do otoliths sit on
Hair bundles
Neural connections of vestibular system
Afferent via 8th cranial nerve to vestibular nuclei in medulla
Efferent sets gain of vestibular system
Gain
Change in the eye angle divided by the change in head angle during the head turn
What does gain modulation allow
CNS to pay more or less attention to vestibular system
- depends on task
The vestibular neural connections are what compared to visual ones
Faster
4 functions of vestibular system
- Control eye (vestibulo-ocular reflex)
- Controls head on trunk position (head +body controlled differently)
- Maintains upright posture
- Support Lower limb extensions during locomotion
Vestibulo-ocular reflex (VOR)
Stabilizes image on retina when head moves
What does vestibular system do during VOR
Sends info about how fast the head is moving
What does occulomotor systems so during VOR
Uses info from vestibular to move eyes so the image is stable
3 symptoms of vestibular system dysfunction
Vertigo
Nystagmus
Postural imbalance
Vertigo
Sensation of you or the environment moving even though you are stationary
- BPPV
BPPV
Benign paroxysmal positional vertigo
Nystagmus
Involuntary eye movement (beating)
Postural imbalance
Dizziness, falls, leaning
What 2 dysfunctions often go hand in hand
Vertigo and nystagmus
What is the preferred way to get sensory info
Vision
Why did people adjust posture not to fall in room where wall moved but floors didn’t
Rely more on visual then mechanoreceptors we have for proprioception
Evidence of relying more on vision
- beginnner typists look at their fingers
- beginner dancers look at their feet
Parts of human eye
Optic nerve, iris, cornea, pupil, lens, retina, macula, fovea
Neural components of the eye and vision
Retina, fovea centralis, optic disc, rods, cones, optic nerve (cranial nerve II)
Retina
Light sensitive nerves at back of eye
Receives images - sends to optic nerve - to brain
Fovea centralis
- central vision, most objects seen here
- provide brain with info about what is being seen and how to use it to complete motor skill
Optic disc
- round spot on retina- passage of axons of retinal ganglion cells
- transfer signals from photoreceptors to optic nerve
Rods
Detect low light level
Cones
Detect high light level, colours
Optic nerve (cranial nerve II)
- from retina to brains visual cortex
- transmission of sensory info to brain
When light changes why does blindness occur
Switching from rods to cones or opposite
How is the image refracted on the retina
Upside down and rotated backwards
What does size of image on retina depend on
Distance from the eye
3 techniques for investigating the role of vision in motor control
- Eye movement recording
- Temporal occlusion techniques
- Event occlusion technique
Eye movement recording
- tracks foveal visions ‘point of gaze’
- new vs experienced learner
Ex) what person is looking at
Temporal occlusion techniques
- stop video or film at various times then ask what they are focused on
- spectacles with liquid crystal lenses
Event occlusion technique
Mask view on video or film of specific events or characteristics and ask what focused on
Monocular vision
One eye
What is binocular vision important for
Depth-perception when 3 dimensional features are involved in situation
Ex of when binocular vision important
Reaching- grasping objects
Walking on cluttered pathway
Intercepting a moving object
What is often underestimated without binocular vision
Distances and size of objects
Synonym for central vision
Foveal vision
What is central vision
Directly in front
Middle 2-5 degrees of visual field
What does central vision provide
Specific info to allow us to achieve goals
- size, shape, texture
Examples of specific goals central vision allows
- Reaching/grasping object - specific characteristics like size and shape and required to prepare, move and grasp
- Walking on pathway - specific info to stay on pathway is needed
What is peripheral vision detect
Info beyond central vision limits (upper limit of ~200 degrees)
What does peripheral vision provide
Info about environmental context and moving limbs
When we go through environment, how does peripheral vision detect info
Assessing optical flow patterns
Optical flow
Rays of light that strike the retina
Vision for perception
Central vision
What is central vision anatomically referred to
Ventral stream from visual cortex to temporal lobe
What is central vision for
Fine analysis of a scene (form, features, colour, texture)
Typically available to consciousness
Vision for action
Peripheral vision
What is peripheral vision anatomically referred to as
Dorsal stream from visual cortex to posterior parietal lobe
What is peripheral vision for
Detecting spatial characteristic of a scene and guiding movement
Typically not available to consciousness (ex. Sport, driving a car)
Can still get info (subconscious)
What is perception referred to as
“Coupling” of vision and movement
Example of perception in research
Results showed that spatial and temporal characteristics of limb movements occurred together with specific spatial and temporal characteristics of eye movements (eye before movement)
Examples of when eyes move before limb movements
Catching a ball
Picking up pen
Putting key in keyhole
needed for movement corrections
Vision as feedback
Vision’s feedback role during movement
What is the amount of time needed for movement corrections
Do not know amount of time to detect an error and make correction
If speed is too fast or distance too short to allow any movement modification, what does success at catching the ball depend on
Initial hand position
If person climbing stairs too fast to allow for foot position adjustments while foot on flight, what increases
Risk of falling
What are the 5 roles of vision in motor control
- Monocular vs binocular vision
- Central and peripheral vision
- Perception
- Amount of time needed for movement corrections
- Time to contact
What situations does time to contact (optical variable) concern
- object moving to person must be intercepted (catch or hit ball)
- person moving toward object needs to contact or avoid contact with object
What provides info about time-to-contact
Vision, which the motor control system uses to initiate movement
How does vision initiate movement
Automatic: specification based on changing size of object on retina
- at critical size, requisite movement initiated (ex. Moving out of way of something coming at you)
What is the motor control benefit to vision
Automatic movement initiation
