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32 Cards in this Set
- Front
- Back
Derivation
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The paring of eletrodes in a differential amplifier
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Channel
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Displays the difference in electrical potential recorded between 2 electrodes of the derivation
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Montage
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Logically sequencing dervations by planes to systematically view the electrical energy of the brain
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What is the 10-10 system?
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Used in epilepsy and others- when electrodes are placed inbewteen the 10-20 electrodes for a more
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What are the two types of montages?
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Bipolar and referential
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What is a bipolar montage?
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Created when input 2 electrode is the input 1 electrode of the next channel
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Longitudinal Bipolar
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Anterior to posterior (front to back) - double banana
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Transverse Bipolar
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(left to right across the head)
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Circumferential Bipolar
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Around the head passing through 10% marks (hatband/halo)
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What channels make up the left parasagittal?
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Fp1 - F3; F3 - C3; C3 - P3- P3 - 01
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What channels make up the right parasagital?
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Fp2 - f4; F4 - C4; C4 - P4; P4 - O2
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What channels make up the left temporal?
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Fp1 - F7; F7 - T3; T3 - T5; T5 - O1
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What channels make up the right temporal?
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Fp2 - F8; F8 - T4; T4 - T6; T6 - O2
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What channels make up the sagittal?
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Fz - Cz; Cz - Pz
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What is an advantage of a longitudinal montage?
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Clear tracing due to noise cancelation- each group starts with an eye movement artifact and ends with alpha- phase reversals easy to identify- easy to view symmetry between hempispheres
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What is a Common Mode?
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The area between two electrodes that both electrodes pick up and is therefore canceled out
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What are the disadvantages of a longitudinal Montage?
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not a true representation of volatage due to cancelation - difficult to determine if activity that stands out is dominant in the parasagittal or temporal areas- end of chains are only partially localized
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Advantages of transvers bipolar montage
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clear tracing due to noise cancellation- left to right across midline helps distinguish if activity that stands out is dominant in the parasagittal or temporal areas
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Disadvantage of a transverse bipolar montage
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Symmetry between hemispheres not as well detected as LB
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Advantages of a circumferential Bipolar Montage?
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Further localize at the end of the chain - effects Fp1- Fp2- O1- O2
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Disadvantage of a circumfrential bipolar montage
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Can be confusing when looking at frontopolar and occipital areas
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Advantages of a referntial Montage?
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True representation of voltage (quiet reference)
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Disadvantages of referntial Montage?
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Contaminated reference- Reference electrode not really neutral.
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What are the arrangements of referential montage?
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Left/Right Military style- Vertex Style (referenced to Cz)
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What is an average reference montage?
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Mathematical calculation - adds the voltages of each electrode and divides the total number of electrodes. Usually omits electrodes with higher voltages and electrodes effected by a focus
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advantages of an average reference montage
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true representation of voltage (quiet reference)- localilize focal activity- if the same noise is present in all electrodes then the refernce elecrode will cancel all that out
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disadvantages of an average reference montage
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reference is not really neutral- hard to determine what electrodes to use in the reference- contamination of reference
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Laplacian reference montage
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The reference is a mathmatical average of four surrounding electrodes (example C3 - referenced to average (F3 + P3 + Cz + Tz)/4
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advantages of laplacian reference
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true representation of voltage- helps localize focal activity
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disadvantages of laplacian reference
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reference electrode not really neutral- hard to determine electrodes to include when 1 electrode is on the edge of the array- contamination of reference- different reference for each electrode
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Things to help us visually see an EEG
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Leave a gap between planes- change color of planes
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What is the system reference?
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incoming signal is recorded using a common reference electrode- the computer then cancels out what is common in all of the electrodes to get the true voltage of each input and cancel out the reference montage
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