EEG Flashcards

1
Q

An ERP is the summation of…

A

postsynaptic potentials in pyramidal cells.

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2
Q

What is a postsynaptic potential?

A

When neurotransmitter bind to the membrane of the postsynaptic cell.

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3
Q

What is an electric dipole?

A

A separation of positive and negative charges.

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4
Q

Scalp electrodes measure the voltage from…

A

the summation of multiple dipoles.

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5
Q

Observed ERP waveforms reflect the sum of several independent…

A

latent (hidden) components.

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6
Q

The temporal resolution of EEG is in…

A

milliseconds.

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7
Q

What are the advantages of EEG?

A

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

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8
Q

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

A

neuro-cognitive processes.

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9
Q

What areas of basic research can be done with ERPs?

A

Attention
Memory
Language
Visual cognition

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10
Q

What areas of clinical research can be done with ERPs?

A

Schizophrenia
Neurodegenerative disorders
Depression & anxiety

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11
Q

What is divergence of temporal resolution?

A

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

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12
Q

Divergence allows us to say that the brain…

A

discriminates between 2 conditions at a specific time.

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13
Q

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

A

stimulus processing, decision making

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14
Q

Divergence cannot tell us…

A

when discrimination between conditions begins.

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15
Q

What is sub-division of processing?

A

Identifying differences between ERPs at different time points.

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16
Q

Sub-division of processing s dependent on…

A

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

17
Q

Covert monitoring can assess neural processes in people who…

A

may have difficulty providing a response.

18
Q

Without overt behaviour in cover monitoring it can be…

A

difficult to interpret the results.

19
Q

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

A
  • 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.
20
Q

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

A
  • Principal component analysis

- Independent component analysis

21
Q

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

A

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

22
Q

Why are postsynaptic potentials recorded rather than action potentials?

A

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

23
Q

What issues are there with interpreting/measuring ERPs?

A
  • 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.
24
Q

What is the superposition problem?

A
  • 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.
25
Q

What is latency jitter?

A

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

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