cerebral cortex tutorial

Question 1

What is MS?

Answer 1

Autoimmune neurodegenerative condition where myelin is attacked causing dyemilination and therfore affecting neuronal conduction

Question 2

What are main symptoms of MS?

Answer 2

Blurred visioon, fatigue, difficulty walking, spasms, paraesthesia, muscle stiffness

Question 3

What can an electrical stimulus of appropriate intesntiy to a peripheral nerve do?

Answer 3

Can activate both sensory and motor axons

Question 4

What is an M (Motor) wave? What are they recorded by? What is resposible and what rate?

Answer 4

M wave is a quick reflex recorded by EMG that activates Motor axons which causes AP to go down nerve and stimulate msucle contraction in muscle (twitch)

Question 5

What is an H-reflex/wave?

Answer 5

H-reflex is later response caused by activation of sensory neurones which go to spinal cord to activate motor axons which then move down nerve to activate muscle contraction (twitch) - reflex

Question 6

Wjat is an F-wave? Rate? Is it a reflex?

Answer 6

F -wave is wave caused by a large electrical stimulus causing motor axons to move antidromically (opposite direction), motor axons move to spinal cord ot activate lower motor neurones which then go and cause musuclar contraction. It is not a reflex

Question 7

What is orthrodromic and antidromic?

Answer 7

Orthrodromic is travelling in normal direction of nerve fibre, antidromic is opposite direction of nerve fibres

Question 8

What is transcranial magnetic stimulation TMS used for? What can it activate and what is this response called?

Answer 8

TMS is used for cortical motor stimulation of the brain. It can activate UMN so that AP travels down whole motor pathway (LMN too) in order to cause a muscle contraction. This is a motor evoked potential (MEP)

Question 9

What is total motor conduction time TMCT?

Answer 9

Time from the brain to the muscle (MEP latency)

Question 10

What is peripheral motor conduction time PMCT and how is it calculated?

Answer 10

Time from spinal cord to muscle along motor axon (M latency + F latency - 1/) / 2. -1 is time for AP reaching LMN to turn aorund

Question 11

What is central motor conduction time (CMCT)?

Answer 11

TMCT- PCMT

from brain to spinal cord

Question 12

What is seen in brain stimulation in MS? What is seen in peripheral nerve stimulation? Where is the problem?

Answer 12

In MS, longer than usual MEP latency but normal F latency so toal motor conduction time is delayed but peripheral conduction time is not so problem is in CNS