Lecture 7

Question 1

proprioceptive closed-loop control

Answer 1

• message goes from motor program to spinal cord to the muscle
• M1 loops back to the spinal cord
• M2 loops back to motor program to readjust

Question 2

information pathway

Answer 2

• two essentially separate visual systems underlie human functioning
• info goes to posterior parietal cortex (dorsal stream) where? ACTION
• info goes to inferotemporal cortex (ventral stream) what? PERCEPTION
• use info from both streams to guide all of our movements

Question 3

ventral stream processing “perception”

Answer 3

• the ventral stream provides info about the WHAT in motor control
• it is sensitive only to events in central vision
• ventral stream vision has access to consciousness: uses the info processing stages
• leads to ACTION
• critical for the identification of objects
• lighting is very important for perception

Question 4

how do we know this about perception?

Answer 4

• optic ataxia- perception only

- no idea how to pick up an object but know what it is

Question 5

dorsal stream movement control “action”

Answer 5

• can interact with an object but do not know what it is
• specialized for online movement control: the WHERE in motor control
• involves the entire visual field; operates non-consciously
• optical flow provides an array of info

Question 6

how do we know this about action?

Answer 6

-visual agnosia- action only

Question 7

optic flow

Answer 7

• time to contact info
• as things moves closer, they look bigger and move faster
• dorsal stream (action) processes this info

Question 8

optical array

Answer 8

optical array: the collection of rays of lights that are reflected from objects in our visual environment

Question 9

optical flow

Answer 9

optical flow: specific to retina, the change of pattern of light rays, from the environment as they flow over the retina during continuous movement of the eye through the environment

Question 10

optical flow and balance

Answer 10

-visual system is able to provide the basis for the smallest of correction to hold posture steady
how do we know this?
-moving walls experiment: built a structure where the walls could move forward or backwards: child would move forward if they walls moved away from them and vise versa
-played with optic flow and peripheral vision
-found that changes in the optic flow of our peripheral vision has an impact on our balance

Question 11

ventral stream of movement control “perception”

Answer 11

• our perception of objects- the difference between a pen and a pencil, or a cup of coffee and a glass of water
• allows us to interact with the object accordingly
• info allows for dorsal stream management of movement

Question 12

addition of the dorsal loop to diagram

Answer 12

• non-conscious
• loops back constantly to guide our movement
• ventral? -we don’t have that loop of info (included in exteroceptive feedback)

Question 13

hearing and motor control

Answer 13

• a delay in hearing auditory feedback can result in slowed speech and errors in timing and movements such as playing an instrument
• vision (even if incorrect) can override correct auditory info
• McGurk effect: visual and auditory don’t match, but the visual overrides the auditory
• we know that vision is dominant over other senses, but it doesn’t always produce a correct outcome

Question 14

hearing and motor control how do we know this?

Answer 14

-sound accompanying movement
How do we know this?
-stroke patients and in those with CP, in a reaching task: RT and MT are faster, and movement trajectories are actually smoother, more consistent from trial to trial
-dance ex)