62 Neurophysiology tutorial 3 Collective property of cortex

Question 1

EEG (Electroencephalogram) is a non-invasive and painless technique that record activities from ______________________ by surface macro electrodes placed at specific locations on the _________.

Answer 1

a large population of neurons simultaneously;

scalp

Question 2

Alpha rhythms has a lower/higher amplitude than beta, representing a relaxed/intense mental state.

Answer 2

higher;
relaxed

• beta: high frequency small amplitude

Question 3

Why does concussion causes

1. retrograde amnesia?
2. anterograde amnesia?

Answer 3

1. Hippocampus is affected and shut down due to inadequate blood supply to it during the trauma, memory cannot be formed during the event
2. Recovery of the hippocampus takes time, cannot form new memory right away

Question 4

What kind of neural activity in the brain does EEG record?

Answer 4

• Both action potential and synaptic potential.
• synaptic potential more (by summation) because it lasts longer and has higher chance to be superimposed - easily summated and be picked up.

AP- fast, non-synchorized

Question 5

How surface macro electrode could pick up small electrical activities inside the brain?

Answer 5

record electrical activity from small areas of the brain (summation of neural signals> big enough to be picked up by electrodes) > measure synchronised signals from large population of neurons

Question 6

Limitations of EEG?

Answer 6

• cannot get information from deep brain areas like the basal ganglia, only cortical activity
• low spatial resolution (limited no. of electrodes

Question 7

Advantages of EEG?

Answer 7

1. convenient
2. non-invasice
3. real-time recording (vs MRI)

Question 8

What does sharp, big amplitude ossification mean in EEG?

Answer 8

Focal epilepsy seizures.

= in some cortical areas only not entire (VS general epilepsy)

Question 9

Hallucination of burning smell?

Answer 9

Primary olfactory area is around uncus and entorhinal area with close proximity to the hippocampus