Lec 7: Motor Control

Question 1

electromyography (EMG)

Answer 1

• used to measure and record the electrical activity produced by skeletal muscles
• can measure extent to which they are contracted or relaxed

Question 2

neuromuscular junction

Answer 2

• where muscle fibre and motor neuron communicate
• communicate via acetylcholine (Ach)
• release of Ach can trigger muscle contraction

Question 3

Plegia

Answer 3

paralysis of a body region

Question 4

Paresis

Answer 4

weakness/partial paralysis

Question 5

What can damage about T1 produce?

Answer 5

quadriplegia: inability to move all 4 limbs
- because somatosensory and motor info for whole body is at the top of the spinal cord

Question 6

What can damage below T1 produce?

Answer 6

paraplegia: inability to move lower 2 limbs

Question 7

When is bilateral motor impairment common?

Answer 7

• spinal cord injury
• common because spinal cord is a bundle of nerves adjacent to each other controlling the left and ride side of the body

Question 8

When is unilateral motor impairment common?

Answer 8

most common with brain injury

Question 9

Corticospinal tract

Answer 9

• signal orignates in the primary motor cortex
• travels down the midbrain and medulla
• signal crosses at the medullary pyramids
• goes down to the level of the spine that is appropriate given what it is controlling
  ie. if controlling arms it will branch off to higher part of the spine

Question 10

internal capsule

Answer 10

• large bundle of white matter that carries motor and sensory signals to and from the cerebral cortex
• leaves motor cortex en route to brainstem

Question 11

hemiplegia

Answer 11

paralysis of half of the body

Question 12

hemiparesis

Answer 12

weakness/partial paralysis of half of the body

Question 13

Central pattern generators

Answer 13

way to code complex movement that is highly learned and overpracticed
- can explain why animals can still walk after spinal cord resection

Question 14

Hierarchical control of movement

Answer 14

brain may just be activating the central pattern generator which then activates necessary movement

Question 15

M1 neurons

Answer 15

• code the direction of a movement
• different ones have preferred directions of movement

Question 16

population vectors

Answer 16

• represents the collective firing activity of a group of neurons, each of which contributes a component of the vector based on its firing rate and preferred direction (or preferred movement direction)
• different directions of movement combine together to get a desired direction

Question 17

Pariteal cortex and spatial planning

Answer 17

• has 3 different areas that care about the destination of movement
• part of the dorsal stream
  1. Parietal reach region (PRR) reaching
  2. Lateral intraparietal area (area LIP) eye movements
  3. anterior intraparietal area (area AIP) grasping

Question 18

Premotor cortex (PMC)

Answer 18

important for observational learning and understanding actions of others

Question 19

Discovery of mirror neurons in PMC

Answer 19

• originally measuring PMC in monkeys and how the neurons activate with certain movements
• noticed when experimenter would walk up and set something on the table in front of the monkey, PMC would start to activate strongly
• also noticed activation when monkey senses movement even in absence of vision that something is being grabbed from it or monkey grabs something in the dark
• sounds associated with clear actions also activate PMC, probably because we are trying to consider the action causing the sound

Question 20

PMC neurons and peripersonal vs extrapersonal space

Answer 20

• neurons care about where the action is relevant to you
• specific neurons respond to the peripersonal space and others to extrapersonal
• most neurons activate to both

Question 21

Action proximity on PMC activity

Answer 21

• activity is modulated as a function of distance
  extrapersonal: further away the action is from you, the higher the activity
  peripersonal: closer the action is, higher the activity

Question 22

Supplementary motor area (SMA)

Answer 22

• involved in set of actions we have already learned how to do
• strongly activates at first action in a sequence we were taught as if it is trying to deploy knowledge on how to engage the rest of the sequence

Question 23

Cerebellum

Answer 23

• role in motor coordination
• smoothes out movements
• complex
• different parts of the cerebellum control different things