W3L2 - Central Control of Movement

Question 1

How is M1 distributed?

Answer 1

Somatotropic Distribution

• Each area of M1 correspond to a particular region
• Majority of nerves projecting to spinal cord for body movements starts here

Question 2

What are the nerves that take information from M1 to muscles?

Answer 2

• Lateral tracts:
  
  • Control peripheral muscles for fine, precise, discreet movements
• Ventromedial (Medial) tracts
  
  • Control core muscles for postural movements and bilateral movements

Question 3

Elaborate on descending motor tracts (lateral)

Answer 3

Lateral Tracts: Independent limbs

• Axons from M1 and red nucleus (midbain area involved in arm movements) project to spinal cord and cranial nerves
  
  • Axons cross over to contralateral sides in bulges of medulla (pyramids)
  • Axons also project to cranial nerves directly

Question 4

Elaborate on descending motor tracts (ventromedial)

Answer 4

Ventromedial Tracts: Coordinated movements

• Axons from many part of cerebral cortex (not just M1).
• Axons go to BOTH sides of spinal cord.

Question 5

Explain the brain processess in planning and producing a movement

Answer 5

1. ) PPC
2. ) PFC
3. ) SMC and PMC
4. ) M1

Question 6

Planning movement: PPC

Answer 6

PPC

• Receives information about the location of items in space (Controls aim)
• Passes to PFC

Question 7

Planning movement: PFC

Answer 7

PFC

• Stores sensory information, considers possible outcomes once movement begins.
  
  • Creates an action plan.
• Damage here results in illogical,disorganised movements.
• Important for inhibiting movements

Question 8

Planning movement: PMC

Answer 8

PMC

• Learning and completing complex movements
• Receives non-arbitrary and arbitrary information
  
  • Non-arbitrary: PPC (location of arm); PFC (planned action)
  • Arbitrary: When I do x, do Y
• Damage makes arbitary movements problematic

Question 9

Planning movement: SMC

Answer 9

SMC

• Sequences of movements
• Damage causes sequence out of order
• Inhibition of SMC disrupts sequence
• Important for inhibiting habitual motions

Question 10

What is the basal ganglia (input, outputs)

Answer 10

Large group of structures in the forebrain that forms loops with motor regions.

• Input
  
  • M1, Somatosensory
• Output
  
  • M1, SMC, PMC, Brainstem

Question 11

What are the pathways of basal ganglia? And what does basal ganglia fuction to?

Answer 11

Pathways

• Direct: excitatory effect on movement
• Indirect: inhibitory effect on movement

Function

• Regulate the vigour of movement
  
  • Force modulation
• Important for “self initiated” movements and movement inhibition
  
  • “Don’t touch this”

Question 12

What brain structures are important when inhibiting a movement

Answer 12

PFC and Basal Ganglia (That’s why before age 5, poor inhibition due to slow maturation of PFC)

Question 13

What is the function of cerebellum?

Answer 13

Cerebellum

• Balance and coordination
• Rapid, repetitive movements where aim is important
  
  • Start-Stop movements
  • Continous movements (cycling) unaffected by cerebelluar damage

Question 14

What does the lateral zone of the cerebellum do?

Answer 14

Lateral Zone

​Receives information about movment plan/limb location/etc and send to M1 for modification

Damage results in decomposition of smooth movements

Question 15

Summarize motor control

Answer 15

Movements are initiated in cerebral cortex, but assisted and moified by cerebellum and basal ganglia

Question 16

What does motor imagery activate? And what happens when imagining a demanding task?

Answer 16

Motor imagery

• Imagining a movement activates many of the brain regions involved in the early stage of motor control.
  
  • E.g. SMC, PPC, Basal Ganglia, Cerebellum (imagined practice works?)

Demanding Task

• Cardiovascular and respiration increase and the muscles used have increased activity.
• If imagine performing a task to exhaustion then the muscles involve fatigue more quickly.