Lecture 24

Question 1

What does the prefrontal cortex to do for the planning + initiating of movement with an example?

Answer 1

• decisions to move
• plan desired movement outcome
• e.g I plan to sit 10 rows up in the lecture theatre

Question 2

What does the premotor cortex to do for the planning + initiating of movement with an example?

Answer 2

• organizing movement sequence for desired outcome
• e.g walk to the stairs, climb up 10 stairs, step into aisle, sit in seat

Question 3

What does the primary motor cortex to do for the planning + initiating of movement with an example?

Answer 3

• directs voluntary movement
• e.g activate knee flexors, etc

Question 4

What are the features of the basal nuclei?

Answer 4

• influence posture + automatic movements
• refine movements, select which to allow vs which to inhibit
• alters sensitivity of neurons

Question 5

What are the features of the cerebellum?

Answer 5

• stores and facilitates learning, planning and execution of motor programs
• monitors sensory input to compare actual movement to planned input
• organizes timing of muscle contractions and modifies ongoing activity

Question 6

What are the key features of the neuromuscular junction (NMJ)?

Answer 6

• specialized chemical synapse
• between axon terminal of motor neuron and skeletal muscle fibre
• relases ACh, always excitatory
• ACh binds to chem gated Na+ channels and propagates AP to sarcolemms
• summation not usually needed

Question 7

What are the main differences between voluntary and reflex responses?

Answer 7

• voluntary = longer and highly variable latency, reflex = shorter and consistent latency
• voluntary = can be trained to be faster and is complex, reflex = can’t be trained, relatively more simple

Question 8

How does the stretch and reflex response work?

Answer 8

1. tendon tap causes fast, sudden stretch of quads
2. proprioceptors/stretch receptors within muscle get stretched
3. mechanically gated Na+ channels open in membrane of dendritic endings of proprioreceptors
4. Na+ entry causes depolarization that leads to AP, propagates along sensory axon to spinal cord
5. synaptic transmission from sensory axon terminal causes depolarization in motor neuron cell body
6. AP fires and propagates along motor axon to NMJ of quads
7. stimulating quads contract, cause foot to kick out

Question 9

How does the withdrawal reflex work?

Answer 9

1. nociceptors activated
2. sensory neuron depolarizes, AP propagates to spinal cord
3. sensory neuron stimulates interneurons
4. leads to excitation of motor neurons that stimulate flexors, inhibition of motor neurons that stimulate extensors, enables withdrawal of limb