Basic neurophysiology

Question 1

What does an EEG electroencephalogram measure?

Answer 1

Electrical activity of the brain

• produces evoked potentials due to stimulation eg, visual, somatosensory, auditory
• can measure neurotransmission speed

Question 2

What does an EMG electromyography measure?

Answer 2

Electrical activity of skeletal muscles

• motor unit potentials, fibres are spread out in muscle
• small units are recruited early, larger ones when more force is needed

Question 3

What can an EEG provide evidence for?

Answer 3

• Epilepsy, classification and management
• Non-convulsive status epilepticus (prolonged absence, not an obvious attack)
• Non-epileptic attack disorder

Question 4

What are event-related potentials? What are somatosensory evoked potentials?

Answer 4

Event-related potentials = when potentials emerge before the task, so they cannot be evoked but they are related

Somatosensory evoked potentials (SEP/SSEP) - access somatosensory function