MC exam 2: Sensory and Closed Loop Control

Question 1

What is a the closed loop control system?

Answer 1

theory that sensory information is a result of performed actions

essentially after movement nervous system compares to memory for reference of correctness

Question 2

What are exteroreceptors?

Answer 2

tells us about movement in the envirnoment

Question 3

What are proprioceptors?

Answer 3

tells us about movement within our own body

Question 4

What can feedback control be?

Answer 4

1. can be cognitive influence- longer duration like driving a car
2. can be reflexive CNS influence
3. can give you info even if movement happens suddenly

Question 5

What is feed forward control?

Answer 5

sending a signal that readies system for up and coming motor command, bypass feedback like swinging a baseball bat

Question 6

Why can’t we tickle ourselves?

Answer 6

b/c it is the result of the feedback information not matching the feedforward information

Question 7

What is reflexive closed loop control?

Answer 7

allows fast corrective response, decreased time spent in response processing stage

Question 8

What are 3 types of reflexes?

Answer 8

1. monosynaptic stretch reflex- 30-50 ms
2. long loop reflex (50-80 ms)
3. triggered reaction ( 80-120 ms)- this is a highly over learned skill

Question 9

What is closed loop control steps?

Answer 9

1. input
2. reference mechanism
3. executive level
4. effector level
5. environment
6. feedback

Question 10

What are overall characteristics of closed loop control?

Answer 10

not very efficient

roughly 150 ms

Question 11

How does light come into the eyes?

Answer 11

focused by cornea and lens then travels to the retina where there are photoreceptors

Question 12

What are the two photoreceptors?

Answer 12

rods- night vision

cones- daylight and color vision

Question 13

Where does the signals from nasal retina cross?

Answer 13

optic chiasm

Question 14

How does eye vs brain image differ?

Answer 14

eyes- see basic features

brain- reassembles images

Question 15

What is the role of vision?

Answer 15

tell us about our movement and movement in environment as well as posture, locomotion and manipulation

Question 16

Who were Mishkin and Ungerleider?

Answer 16

the theorized the dorsal and ventral stream in vision

Question 17

What is the ventral stream?

Answer 17

The “what” stream- mostly central responsible for object ID and perception of the environment like color, contours and contrast

defecits in this area lead to - agnosias

Question 18

What part of brain is ventral stream?

Answer 18

inferotemporal

Question 19

What is the dorsal stream?

Answer 19

Where and How stream, full visual field 180 degrees

info about environment when walking like movement depth and coarse detail

Question 20

What part of brain is dorsal stream?

Answer 20

posterior parietal

Question 21

What is simultaneous agnosia?

Answer 21

can tell two items apart but when they are together the pt can’t recognize btwn the two objects

Question 22

What is optic ataxia?

Answer 22

can see objects but can;t localize them- dorsal stream lesion

Question 23

What is face blindness?

Answer 23

prosopagnosia, can see face features but can’t tell who it is

Question 24

What is object blindness?

Answer 24

visual agnosia, trouble seeing words and objects- ventral stream lesion

Question 25

What is the size of a retinal image?

Answer 25

“A”, change in size of object as it approaches

bigger as it approaches

Question 26

What was Woodworth’s experiment to measure time required to process visual feedback?

Answer 26

repetitive aiming with/without vision, tried to slow down a movement to allow for longer time for vision

estimated 250 ms

Question 27

What was Keele and Posner experiment?

Answer 27

refined Woodworth’s experiment for discrete aiming movements

time: 250 ms

Question 28

What was Zelaznik experiment?

Answer 28

135 ms if allowed to participate

Question 29

What is the vestibular system?

Answer 29

the conflict resolver between vision and somatosensory system

Question 30

What are two otolith organs?

Answer 30

saccule and utricle

sensitive to gravity and linear motion

Question 31

What are 3 semicircular canals?

Answer 31

fluid filled half circles, determine rotation of head

contain hair cells that are innervated by nerves

Question 32

What is the cochlear?

Answer 32

part of auditory system to help localize objects in the inner ear

Question 33

What is organ of corti?

Answer 33

sensory organ of hearing

Question 34

What is the somatosensory system?

Answer 34

the perception of stimuli from skin and internal organs of body aka proprioceptive system

fastest of all three sensory systems, very imp for motor control but great undervalued

Question 35

What are 3 major components of somatosensory system?

Answer 35

1. muscle receptors- muscle spindle and golgi tendon organ
2. joint receptors
3. cutaneous receptors- mechano-, thermo-, nociceptors

Question 36

What are muscle spindles?

Answer 36

senses position/stretch, maintains muscle stiffness, helps regulate muscle length during movement

Question 37

What types of afferent fibers originate from muscle spindle?

Answer 37

Ia and II- sensory afferent

Question 38

What do gamma motor neurons do with muscle spindles?

Answer 38

send efferent signal to intrafusal muscle fibers

Question 39

What do intrafusal muscle fibers do?

Answer 39

keep correct muscle tension when muscle is shortened or lengthened

contract to stretch muscle spindle

Question 40

What type of reflex is associated with a muscle spindle?

Answer 40

monosynaptic stretch reflex

Question 41

What is role of Type 1a fibers?

Answer 41

wrap around most elastic part of muscle fiber (nuclear bag) and are most sensitive to muscle stretch (dynamic)

Question 42

What is role of type 2 fibers?

Answer 42

wrap around less elastic muscle region of the muscle fibers and therefore most sensitive to static stretch

Question 43

How does a monosynaptic reflex work?

Answer 43

1. muscles is streched- exites 1A fibers
2. excitatory monosynaptic connection to the alpha motor neuron to activate agonist
3. activates synergist muscles
4. also synapse on interneurons to inhibit antagonist

Question 44

What is long loop reflex?

Answer 44

functional stretch reflex- modifiable according to the task of the environment

Question 45

What is role of gamma motor neurons?

Answer 45

activated same time as muscle during voluntary contraction, allows muscle spindles to be active during a voluntary contraction