Module 2: Upper Motor Neurons

Question 1

what is the M1

Answer 1

primary motor area

Question 2

what is PMA

Answer 2

premotor area

Question 3

what is SMA

Answer 3

supplementary motor area

Question 4

where are upper motor neurons located

Answer 4

on the dorsal/lateral as well as the medial surface of the brain

Question 5

what parts of the body does the corticospinal tract innervate

Answer 5

upper extremities, trunk, lower extremities

Question 6

what does the corticobulbar tract innervate

Answer 6

face

Question 7

what are the three major motor cortical areas

Answer 7

primary motor, premotor, supplementary motor cortex

Question 8

where do the 1b afferents synapse?

Answer 8

onto inhibitory interneurons that synapse on the same alpha motor neuron that is contracting

Question 9

1b afferents function

Answer 9

inhibit ‘over-contraction’

Question 10

what happens when the AMPA receptor is open

Answer 10

the channel undergoes rapid desensitization, stopping the current

Question 11

where does the corticospinal tract come from

Answer 11

direct output from the primary motor cortex

Question 12

how to determine which cortical motor neurons to include in decoding upper motor neuron activity

Answer 12

neurons that reliably fire prior to the movement are likely participating in the movemtn

Question 13

step one of decoding upper neuron activity that controls the direction of arm movements

Answer 13

determine which cortical motor neurons to include: those that control muscle activity for a given movement

Question 14

step 2a of decoding upper neuron activity that controls the direction of arm movement

Answer 14

record activity of a single neuron prior to arm movement in 8 directions

Question 15

what is the use of a raster plot

Answer 15

showing a long string of linear data on a trial-by-trial basis

Question 16

step 2b of decoding upper neuron activity that controls the direction of arm movement

Answer 16

plot a directional tuning curve that depicts all of the raster plots as a curve

Question 17

how can you identify the neuron’s ‘preferred’ direction of movement?

Answer 17

the direction prior to which it fires the most

Question 18

step 3a of decoding upper neuron activity that controls the direction of arm movement

Answer 18

represent that neuron’s firing level prior to each of the 8 directions as a vector; the angle of the vector is the preferred direction of movement

Question 19

step 3b of decoding upper neuron activity that controls the direction of arm movement

Answer 19

do step 3a for all of the neurons you recorded

Question 20

Imagine the arm is controlled by just two neurons. One neuron prefers firing prior to movement in the 0 degree direction. The other prefers firing prior to movement in the 90 degree direction. If they both fire equally, which way will the arm move?

Answer 20

45 degrees

Question 21

how is the population vector calculated

Answer 21

the contributions of cells that fire during movement in a particular direction are added vectorially to produce a population vector; the direction of the vector indicates direction

Question 22

mirror neurons

Answer 22

cortical neurons that exhibit both motor and sensory properties

Question 23

when do mirror neurons fire

Answer 23

• prior to a movement (premotor)
• when the animal sees another being perform the same movement (sensory)
• when a subject hears the sound normally associated with that movement

Question 24

what are mirror neurons well-situated for

Answer 24

• mimicry
• empathy
• interpreting intent of another’s action

Question 25

plasticity in neuroscience

Answer 25

means changeable

Question 26

synaptic plasticity

Answer 26

synapses get stronger or weaker

Question 27

anatomical plasticity

Answer 27

changes in the structure of neural connections

Question 28

behavioral plasticity

Answer 28

learning

Question 29

three medial descending tracts involved in head position, balance, and posture

Answer 29

tectospinal, reticulospinal, vestibulospinal

Question 30

where does the reticulospinal tract project from/to

Answer 30

from the reticular formation to local circuit neurons that coordinate axial and proximal limb muscles

Question 31

what is the reticulospinal tract controlled by

Answer 31

other motor centers in cortex or brainstem

Question 32

what is the reticulospinal tract important for

Answer 32

stabilizing posture dring ongoing movements

Question 33

mesencephalic and rostral pontine reticular formation function

Answer 33

modulates forebrain activity

Question 34

caudal pontine and medullary reticular formation function

Answer 34

premotor coordination of lower somatic and visceral motor neuronal pools

Question 35

what kind of mechanism does postural control entail

Answer 35

feedforward mechanisms

Question 36

how are the connections between upper and lower motor neurons organized

Answer 36

somatotopically

Question 37

true or false: there is little evidence for anticipatory control

Answer 37

false

Question 38

true or false: the upper motor neuron system neurons are segmentally organized

Answer 38

true

Question 39

true or false: upper motor neurons exhibit a medial to lateral organization

Answer 39

true

Question 40

true or false: there is plasticity in the organization of the upper motor neuron systems

Answer 40

true

Question 41

what pathway is the red nucleus involved in

Answer 41

lateral pathways

Question 42

where does the motor cortex project to (upper motor neurons)

Answer 42

red nucleus, reticular nucleus, superior collliculus and vestibular nuclei

Question 43

what pathway is the reticular nuclei involved in

Answer 43

ventromedial pathways

Question 44

what pathway is the superior colliculus and vestibular nuclei involved in

Answer 44

ventromedial pathways