EEG

Question 1

An ERP is the summation of…

Answer 1

postsynaptic potentials in pyramidal cells.

Question 2

What is a postsynaptic potential?

Answer 2

When neurotransmitter bind to the membrane of the postsynaptic cell.

Question 3

What is an electric dipole?

Answer 3

A separation of positive and negative charges.

Question 4

Scalp electrodes measure the voltage from…

Answer 4

the summation of multiple dipoles.

Question 5

Observed ERP waveforms reflect the sum of several independent…

Answer 5

latent (hidden) components.

Question 6

The temporal resolution of EEG is in…

Answer 6

milliseconds.

Question 7

What are the advantages of EEG?

Answer 7

High temporal resolution
Relatively cheap (compared with fMRI)
Non-invasive

Question 8

ERP component is a scalp-recorded voltage change that reflects specific…

Answer 8

neuro-cognitive processes.

Question 9

What areas of basic research can be done with ERPs?

Answer 9

Attention
Memory
Language
Visual cognition

Question 10

What areas of clinical research can be done with ERPs?

Answer 10

Schizophrenia
Neurodegenerative disorders
Depression & anxiety

Question 11

What is divergence of temporal resolution?

Answer 11

When waveforms for 2 conditions (e.g. - faces and cars) diverge.

Question 12

Divergence allows us to say that the brain…

Answer 12

discriminates between 2 conditions at a specific time.

Question 13

EEG can explain the time course and stages of _______ _______ & _______ ________.

Answer 13

stimulus processing, decision making

Question 14

Divergence cannot tell us…

Answer 14

when discrimination between conditions begins.

Question 15

What is sub-division of processing?

Answer 15

Identifying differences between ERPs at different time points.

Question 16

Sub-division of processing s dependent on…

Answer 16

prior knowledge of what processing stages are involved in a task.

Question 17

Covert monitoring can assess neural processes in people who…

Answer 17

may have difficulty providing a response.

Question 18

Without overt behaviour in cover monitoring it can be…

Answer 18

difficult to interpret the results.

Question 19

Why is it difficult to deconstruct an ERP waveform into its components?

Answer 19

• Peaks & troughs are not always a good reflection of underlying components.
• Changes in amplitude of one underlying component can appear to change the amplitude and latency of a different component in a waveform.
• Differences in peak latency do not always correspond with changes in component timing.

Question 20

What methods can be used to deconstruct ERP waveforms into their underlying components?

Answer 20

• Principal component analysis

- Independent component analysis

Question 21

Why must the results of many trials (usually in the order of 100 or more) be averaged together?

Answer 21

To average out random brain activity, so that just the relevant waveform to remains, called the ERP.

Question 22

Why are postsynaptic potentials recorded rather than action potentials?

Answer 22

Because they last longer, and action potentials may cancel each other out.

Question 23

What issues are there with interpreting/measuring ERPs?

Answer 23

• Waveforms do not reflect all neural activity .
• PSPs last many milliseconds - new mental processes are beginning as previous activations persist.
• Multiple ERP components (related to dipoles) are active simultaneously.
• Superposition problem.
• Latency jitter.
• Between-subjects variability.

Question 24

What is the superposition problem?

Answer 24

• ERP peaks do not = ERP components.
• The observed ERP average is made up of multiple components.
• The shape and latency of underlying components is hidden.

Question 25

What is latency jitter?

Answer 25

The timing of components is not the same on each trial.

Effects the earliest and latest onset/offset time and effects peak amplitude.