Electrophysiological Recordings

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What are micro-electro recordings?
Involves inserting very thin electrodes into the tissue in the hopes of penetrating a single cell. Only carried out on those undergoing brain surgery.
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What do micro-electro recordings measure?
The frequency of action potentials to determine how strong an impulse is.
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What are the strengths of micro-electro recordings (1)?
The most direct and precise measure of brain activity.
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What are the limitations of micro-electro recordings (2)?
Restricted in terms of subjects available and brain areas that can be investigated, strict ethical concerns regarding brain research in animals.
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What is electroencephalography (EEG)?
A non-invasive method that uses between 32 and 64 sensors.
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What does EEG measure?
Changes in voltage, frequency by measuring how rapidly the EEG signal oscillates.
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What can EEG be used to examine?
Sleep behaviour or detecting pathologies (e.g. epilepsy).
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What is higher frequency activity associated with in EEG?
More cortical activity.
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How can epilepsy be observed using EEG?
Abnormal/ excessive synchronisation of post-synaptic potentials in epilepsy results in large amplitude discharges, which can be observed during or between seizures.
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How can conciousness be observed using EEG?
By recording high frequency EEG over the motor cortex to assess concious awareness in patients in a vegetative state.
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What are event-related potentials (ERPs)?
Segments of EEG, time-locked to particular event stimuli. Different types of stimuli are separately averaged then compared.
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What are ERP components?
Features in the waveform.
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How can we attempt to determine the source of EEG/ ERPs?
Brain tissue conducts electricity well, so local field potentials (LFPs) are conducted in all directions. Each point on the head surface reflects cortical activity originating from a distant region.
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How has the problem of pinpointing regions where EEG activity originates been overcome?
By using sophisticated modelling using maths and bio-physics techniques.
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What are the strenghts of EEG (2)?
High temporal resolution so can provide detailed temporal information, the time-course of a component in the ERP along with the scalp tomography can be seen as a spatio-temporal "signature" of a process.
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What are the weaknesses of EEG (1)?
Limited spatial resolution so cannot localise activity in the brain with precision or confidence.
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Other cards in this set

Card 2

Front

What do micro-electro recordings measure?

Back

The frequency of action potentials to determine how strong an impulse is.

Card 3

Front

What are the strengths of micro-electro recordings (1)?

Back

Preview of the front of card 3

Card 4

Front

What are the limitations of micro-electro recordings (2)?

Back

Preview of the front of card 4

Card 5

Front

What is electroencephalography (EEG)?

Back

Preview of the front of card 5
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