Physiology of Motor Control

Question 1

What are the differences between hierarchal and parallel processing?

Answer 1

Hierarchal is a higher level of control involved in cognitive and information processing. Involves abstract information from multiple sources.
Parallel is the same signal processed by several different structures through the cerebellum and basal ganglia.

Question 2

What are the 5 levels of the perception/action hierarchy?

Answer 2

1) spinal cord
2) brain stem
3) Cerebellum
4) Diencephalon
5) Cerebral hemispheres (cerebral cortex and basal ganglia)

Question 3

What is the role of the spinal cord?

Answer 3

• lowest level of processing
• “final common pathway” before muscle activation
• reception and processing of somatosensory information
• simple sensory/motor relationships (M1 reflexes)
• reflexes

Question 4

What is the “final common pathway”, and who coined that phrase?

Answer 4

Sherrington called the motor neurons of the spinal cord the final common pathway because they are the last level of processing before muscle activation.

Question 5

What is the role of the Brain Stem?

Answer 5

Contains important nuclei involved in postural control and locomotion, including the vestibular nuclei.
Contains ascending and descending pathways transmitting sensory and motor info to other parts of the CNS.
Receives somatosensory input from the skin and muscles of the head, as well as sensory input from the vestibular and visual systems.
Sends motor output to the neck, face, and eyes.

Question 6

What information does the brainstem receive?

Answer 6

Receives somatosensory input from the skin and muscles of the head, and sensory input from the vestibular and visual systems.

Question 7

What information does the brainstem send out?

Answer 7

Transmits motor output signals to the neck, face, and eyes.

Question 8

What is the role of the Cerebellum?

Answer 8

Receives inputs from the spinal cord and from the cerebral cortex.

Question 9

What information does the cerebellum receive from the spinal cord?

Answer 9

It receives input from the spinal cord regarding movement feedback.

Question 10

What info does the cerebellum receive from the cerebral cortex?

Answer 10

Planning feedback from the cerebral cortex

Question 11

What role does the cerebellum play in regards to the conceptual model?

Answer 11

It is the comparator…compares feedback from the motor areas and cerebral cortex….ACTUAL VS DESIRED STATES

Question 12

What two structures compose the Diencephalon?

Answer 12

Thalamus

Hypothalamus

Question 13

What is the thalamus responsible for?

Answer 13

It receives and processes information from parallel inputs going to the cortex.

Question 14

What parallel input pathways does the thalamus receive information?

Answer 14

Spinal cord
Cerebellum
Brain Stem

Question 15

What does the hypothalamus link?

Answer 15

CNS info to the pituitary gland for hormonal responses.

Question 16

What two areas are within the cerebral hemispheres?

Answer 16

Cerebral cortex

Basal Ganglia

Question 17

What is the role of the basil ganglia?

Answer 17

Receives information from the cerebral cortex and sends it to the motor cortex via the thalamus. (desired state)

Question 18

What is the role of the cerebral cortex?

Answer 18

Identifies targets
Chooses actions
Programs movements

Question 19

What areas are contained within the cerebral cortex?

Answer 19

Parietal area
premotor areas
Motor cortex

Question 20

What is the role of the parietal and premotor areas?

Answer 20

Identification of targets, choosing a course of action, and programming movements.

Question 21

What does the premotor area do?

Answer 21

Sends outputs to the motor cortex

Question 22

What is the pathway involved for pouring milk?

Answer 22

Sensory input from periphery.
Sensory info about the task: size of glass, weight of milk carton.
Higher centers in the cortex make action plan based on information from sensory areas.
From sensory map in cortex, movement plan established by parietal and premotor cortices.
Plan sent to the motor cortex and muscle groups are specified.
Plan also sent to the cerebellum and basal ganglia to modify and refine the movement to avoid obstacles, etc.
The cerebellum sends uptdate of the movement output plan to the motor cortex and brain stem.
The Descending pathways from the motor cortex and brainstem activate spinal cord networks.
Spinal motor neurons activate the muscles and you reach for milk.
If the milk carton is full when you thought it was empty, spinal reflex pathways will compensate for the extra weight and activate more motor neurons.
Sensory consequences will be evaluated and the cerebellum will update the movement.

Question 23

Summarize the pathway for getting milk.

Answer 23

Input to nonmotor cortex
Sensory map created in parietal and premotor.
Plan sent to motor cortex.
Plan also to cerebellum and basal ganglia.
Cerebellum sends updated info to motor cortex and brain stem.
Motor cortex and brain stem send info to descending pathways.
Spinal motor neurons activate muscles.
Cerebellum evaluates additional sensory information to further refine movement.

Question 24

What is the resting potential of a neuron?

Answer 24

-70mV
K+ inside, Na+ outside
Neuron at rest

Question 25

What is the action potential of a neuron?

Answer 25

K+ moves out, Na+ in Voltage jumps across the cell membrane when voltage reaches -40mV Voltage increases to +30mV

Question 26

What is spacial summation?

Answer 26

multiple synapses on a post synaptic neuron

Question 27

What is temporal summation?

Answer 27

Single presynaptic neuron that sends signal rapidly.

Question 28

What is synaptic facilitation?

Answer 28

When more neurotransmitter is released and depolarization is easier due to a threshold of -55mV

Question 29

What is habituation?

Answer 29

When less neurotransmitter is released. Depolarization is harder Threshold is -40mV

Question 30

Whta is the somatosensory system?

Answer 30

Proprioception, visual, and vestibular information

Question 31

What comprises muscle spindles?

Answer 31

Intrafusal fibers Sensory neurons Gamma motor neurons

Question 32

What are Intrafusal fibers?

Answer 32

Small, specialized muscle fibers that provide signals to the 1a and 2 afferent nerves

Question 33

What role do nuclear bag intrafusal fibers play?

Answer 33

Stretch quickly when lengthened and signal 1a neurons to rate of change and dynamic muscle length

Question 34

What is the role of nuclear chain intrafusal fibers?

Answer 34

Stretch slowly when lengthened and signals 1a and 2 afferent nerves to both dynamic and static muscle length

Question 35

What do 1a sensory nerves indicate?

Answer 35

1a are sensitive to rate of change, or dynamic muscle length and receive info from nuclear bag and chain fibers.

Question 36

What do 2 afferent nerves respond to?

Answer 36

steady state, static muscle length from nuclear chain fibers

Question 37

What are gamma motor neurons?

Answer 37

Activate both bag and chain muscle fibers

Question 38

What is the dynamic role of gamma motor neurons?

Answer 38

Innervate dynamic bag muscle fibers to enhance dynamic response of 1a afferents

Question 39

What is the static role of gamma motor neurons?

Answer 39

innervates both static bag and chain, and enhances static response of 2 afferents

Question 40

What is the role of dorsal root ganglion in sensation?

Answer 40

these first order neurons send info from somatosensory systems (muscles, proprio, visual, etc) to higher brain centers

Question 41

What info do anteriolateral systems provide?

Answer 41

Info about crude touch and pressure. | Info about thermal and pain to higher centers

Question 42

What areas do dorsal and anteriolateral systems go to?

Answer 42

Thalamus and somatosensory cortex (parietal, premotor)

Question 43

What information does the thalamus receive?

Answer 43

Info from both ascending tracts | Info from other brain centers

Question 44

What other roles does the thalamaus serve?

Answer 44

Relays between subcortical structures and cerebral cortex. | Also processes sensory info

Question 45

What is the role of the somatosensory cortex?

Answer 45

major processing area for ALL somatosensory modalities. Conscious awareness of sensation. Integrates multiple sources of informatoin to provide ino about movement of a given body area.

Question 46

What are the two visual streams?

Answer 46

Dorsal and Ventral

Question 47

What info is carried through the Dorsal Stream?

Answer 47

Info through retina to primary visual cortex Posterior parietal cortex For visual control of movement Action

Question 48

What info is the ventral stream responsible for?

Answer 48

Info through retina to primary visual cortex, into inferotemporal cortex. Cognitive info about environment - identification and recognition Perception of what something is.

Question 49

What comprises the vestibular system?

Answer 49

Peripheral receptors | Central Connections

Question 50

What are the peripheral recepters?

Answer 50

part of the inner ear labyrinth Semicircular canals Utricle and Saccule

Question 51

What are the semicircular canals?

Answer 51

Detect angular motion of the head

Question 52

What do the Utricle and Saccule do?

Answer 52

Identify body position with reference to gravity and linear acceleration of the head

Question 53

Where does info from the peripheral receptors of the vestibuluar system go?

Answer 53

the ascend to vestibular nuclei

Question 54

What areas comprise the Motor cortex?

Answer 54

primary motor cortex Supplementary motor area Premotor cortex

Question 55

What is the role of the motor cortex?

Answer 55

Interacts with the sensory processing areas to identify where we want to move, plan movement, and execute actions.

Question 56

What areas does the motor cortex interact with?

Answer 56

Sensory processing areas of the parietal lobe, the basal ganglia, and cerebellum

Question 57

What is the role of the Primary motor cortex?

Answer 57

provides map of the body | enervate muslces

Question 58

What does the primary motor cortex provide info about?

Answer 58

Absolute force | Movement speed

Question 59

Where does the primary motor cortex get info from?

Answer 59

``` Basal Ganglia Cerebellum Sensory areas Somatosensory cortex Association cortices of parietal lobe ```

Question 60

Where does the primary motor cortex send info TO?

Answer 60

Corticospinal tract Monosynaptic connections with alpha motor neurons (M2) Polysynaptic connections to gamma motor neurons Polysynaptic connections with spinal cord

Question 61

Where does the supplementary motor area get information from?

Answer 61

Thalamus Basal Ganglia Parietal Cortex

Question 62

Where does the supplementary motor area send info to?

Answer 62

primary motor cortex | spinal cord

Question 63

What is the supplementary motor area responsible for?

Answer 63

Motor planning, learning internally reference movements Controls internally initiated movements Activates motor programs Learns sequences

Question 64

What are the association areas of the frontal cortex responsible for?

Answer 64

``` Prefrontal cortex Executive decision attention decision making motor planning integration of sensory information selection of motor response ```

Question 65

What are the three areas of the cerebellum?

Answer 65

Flocculonodular lobe Vermis and intermediate hemispheres Lateral hemispheres

Question 66

What is the role of the flocculonodular lobe?

Answer 66

Receives input from visual and vestibular systems, and outputs return to the vestibular nuclei

Question 67

What is the role of the vermis and intermediate hemispheres?

Answer 67

Receives proprioceptive feedback and cutaneous inputs from the spinal cord. visual vestibular auditory info also

Question 68

What do the lateral hemispheres do?

Answer 68

receives info from brainstem which relays info from wide areas of the cerebral cortex. Plans movement and evaluates sensory info for the motor learning process