Cerebral Cortex Tutorial

Question 1

What is MS? (Multiple Sclerosis)

Answer 1

Autoimmune disease, CNS disorder - only in the brain and spinal cord (not the neurons between the CNS and muscles AKA the PNS)

Attacks the myelin sheath on axons (the insulator)

Question 2

What are the symptoms of MS?

Answer 2

Numbness

Fatigue

Tingling

Muscle spasms, stiffness and weakness

Mobility problems

Pain

Vision problems

Cognitive issues - thinking, learning planning

Question 3

How can brain and nerve stimulation help to confirm the central nature of MS?

Answer 3

Stimulate a part of the brain and see the time it takes for the response

In MS, the response time would be slower as the axons are not myelinated, so nerve impulses are less efficient

Question 4

When a signal is passed through a nerve, what axons are stimulated?

Answer 4

Sensory and motor

Question 5

What are M-waves, F-waves and H reflexes and what information can they provide? Imagine a person has PNS stimulation. What are the M, F and H waves?

Answer 5

M-wave = stimulates purely motor, goes straight down from point of electrical stimulus to the muscle- causes a twitch the fastest

F-wave = is a late response that follows the motor response (M). It is purely motor - motor nerve innervation from electrical stimulus to the cell bodies in the spinal cord, then synapses onto another motor neuron that comes down to cause the twitch

H-wave = reflex therefore causes a twitch after the M wave because it has to go via the spinal cord, all the way around - involves sensory and motor axons - from electrical stimulus up to the spinal cord via sensory axon, then down via motor axon

For PNS stimulation, in someone with MS these responses should be normal as the CNS is not being used. Latency period should only be longer if you stimulate the brain / spinal cord.

Question 6

What can the magnetic cortical stimulation/transcranial magnetic stimulation (TMS) of the motor cortex activate (what major pathways/neurons are activated) and what information can this provide?

Answer 6

Electromagnet delivers magnetic pulse to stimulate the nerve cells int he pre-motor cortex - motor pathways for the movement of the limbs and facial muscles are activated via the corticospinal and corticobulbar tracts

By decreasing activity, the TMS can create a temporary lesion in the brain, and you can look at what functional roles have been taken away????

Question 7

What are the normal latency values from stimulation techniques and investigate how these values compare in patients with MS?

Answer 7

idk