Chapter 5 (lectures 5-7)

Question 1

Main sensory frames of reference

Answer 1

Proprioception
exproprioception
exteroception

Question 2

proprioception

Answer 2

-sense of position and movement relative to another

Question 3

exproprioception

Answer 3

provides information about the position and movement of a part of the body relative to the exernal environment

Question 4

exteroception

Answer 4

provides information about the location of objects in the external environment

Question 5

Touch receptors

Answer 5

Meissner's corpuscle: light touch 
Merkle's corpuscle: touch 
Pacinian corpuscle: vibration and deep pressure 
free nerve endings: pain 
Ruffini corpuscle: warmth

Question 6

Touch and Motor control

Answer 6

provides:
1. movement accuracy
2. movement consistency
3. movement force adjustments
4. helps with the control of balance
5. provide proprioceptive information

Question 7

How is proprioception sensed

Answer 7

Muscle spindles: sense when muscle is lengthening involuntarily
golgi tendon organs: detect force within the muscle
joint receptors: nerve endings, joint angle, especially active at the end range of the joint

Question 8

Manipulating proprioception

Answer 8

Deafferentation: the interruption or destruction of the afferent connections of nerve cells,
Tedon vibration: to investigate kinesthetic illusions in the isometric limb and end point control in the moving limb

Question 9

Role of proprioception

Answer 9

• affects movement accuracy
• affects timing of movements
• affects coordination of movements (postural control, ability to adapt to different environmental situations)

Question 10

Vestibular system

Answer 10

-provides information about the head position; assists in visual fixation during head and/or body movement; important for posture and balance

Question 11

The visual system

Answer 11

• PRIMARY exteroceptive source of sensory information

- primary source of sensory information that is used for controlling goal directed movements

Question 12

Vision pathways

Answer 12

• Visual cortex on the opposite side of the brain

- pathways cross over at the optic chiasm

Question 13

Central vision

Answer 13

• foveal/focal vision

- can only process information in small areas (2-5 degrees)

Question 14

peripheral vision

Answer 14

-everything outside the limits of central vision

Question 15

Time to use vision (hitting a baseball)

Answer 15

• hitting a softball is actually harder (less time to react)

- players only have about 0.400 seconds to make a decision and swing the bat

Question 16

2 visual streams

Answer 16

-once vision reaches the primary cortex, processed in two parallel decoding pathways

Question 17

ventral stream

Answer 17

“what” stream. Helps us identify objects in our visual environment
-primary input is limited to central vision

Question 18

dorsal stream

Answer 18

“where stream” helps us guide our movements

Question 19

evidence of two visual streams

Answer 19

• brain imaging studies
• individuals with brain injuries (sometimes can see something but cannot place it)
• interacting with visual illusions

Question 20

Time to contact (Tau)

Answer 20

• the amount fo time remaining before you will make contact with an object in the environment
• appears to be a function that is determined by our brain, by measuring the rate of change of the size of an object on the retina

Question 21

Lifting a glass: what sensory receptors and information would be used if we had to walk to the table

Answer 21

• visual to see the glass: central vision with dorsal and ventral streams
• tau: to determine when we will contact the glass
• proprioception and exteroception

Question 22

What is a reflex?

Answer 22

• an action that is performed as a response to a stimulus and without conscious thought
• requirements:
  1. input (stimulus)
  2. automatic processing
  3. response

Question 23

The stretch reflex

Answer 23

1) stimulus- fast stretch of muscle
2) sense organ excited- muscle spindle Ia and II sensory neurons
3) primary response- muscle that is stretched contracts rapidly

Question 24

Typical reflex arc

Answer 24

1) sensory neuron- detects stimulus
2) interneurons- most often, can be excitatory or inhibitory
3) motor neurons- produce muscle contraction, motor response

Question 25

Synapse

Answer 25

group Ia and group II

Question 26

Group Ia synapses

Answer 26

monosynaptic connections with alpha motor neurons (fastest reflex known, delay about 1 msec)

Question 27

Group II synapses

Answer 27

1) make monosynaptic connections- direct to motor neuron | 2) polysynaptic connections to motor neuron (through interneruons)

Question 28

Other components to stretch reflex

Answer 28

1) excite synergist muscles: spindle afferents also make excitatory monosynaptic connections with synergist muscles 2) inhibit antagonist muscles

Question 29

Function of stretch reflex

Answer 29

- Maintaining balance when standing 1) tilting forward stretches the muscled on the back of the leg 2) muscles rapidly contract to maintain balance

Question 30

Typical reflex

Answer 30

1) sensory neuron 2) internuron carry signal 3) motor neuron

Question 31

long loop reflexes

Answer 31

myotatic reflexes (autogenetic), long-loop reflexes, triggered reactions, reaction time

Question 32

Reaction time (RT)

Answer 32

- used to determine how long it takes to prepare and initiate movement - the time from stimulus identification and response initiation - provides a window into the mental processes underlying motor skill performance

Question 33

Simple RT

Answer 33

stimulus is one signal | response is one action

Question 34

choice reaction time

Answer 34

more than one signal, each with its own response

Question 35

is RT trainable?

Answer 35

Not really, people can try to cheat it though

Question 36

How can we improve reaction time?

Answer 36

- change the intensity of the signal - change the clarity of the signal - limit number of choices - simplify the task

Question 37

Practice for RT

Answer 37

a) helps us key in on relevant stimuli | b) helps us build stimulus-response compatibility

Question 38

Ways to cheat reaction time

Answer 38

- prior knowledge | - anticipation

Question 39

Hick's Law

Answer 39

reaction time is proportional to the number of equally likely choices an individual has RT=b*log(base 2) (n+1) -b is a constant, n=number of choices

Question 40

Bits of information

Answer 40

- the units of the log2(n) term in the Hick's Law equation - # of choices= 2^n (bits) - yes/no choice = 1 bit

Question 41

Application of Hick's law

Answer 41

- volleyball (pass, to set to hit) | - hockey (making decison to save puck)

Question 42

How do we control our movement?

Answer 42

tons of theories - closed loop control - open loop control - motor programs

Question 43

theories

Answer 43

- help understand phenomena - explain why phenomena exist or the behaviour - can help optimize learning, instruction and feedback

Question 44

Closed Loop control vs. open loop control

Answer 44

closed loop uses feeback, open loop does not

Question 45

Closed loop control

Answer 45

- feedback is used by the CNS to make corrections to the ongoing movements - slower than open loop - sensory feedback can originate from a number of sources - goal is to stay within a certain area (kind of like thermostat) - processes DO NOT reuire detailed initial movement plans - ongoing movement is regulated by an error detection processes

Question 46

Keele and posner (1986) study

Answer 46

- participants were trained to move a hand held stylus ti small target at different movement times - after practice, the lights were turned off - no difference in movement accuracy when movement time was short - error increased when movement was 350ms - further increase in error when movement was 450ms

Question 47

Smith, Roberts and Atkins (1972) study

Answer 47

- sensory nerves blocked with anesthetic - CNS did not receive information from muscle spindles - task was to have participants touch their own noes - hand crashed into face

Question 48

Benefits of closed loop control

Answer 48

used to produce new movements provides flexibility used to provide accurate movements during fine motor tasks

Question 49

Cons of closed loop control

Answer 49

- requires attention - increased accuracy demands require increased error corrections - time constraints (generally takes about 100-200ms before corrections can be made, too slow for ballistic motor skills)