Rowan's Primer Flashcards
Where is the origin of EEG signal?
EEG records and measures voltage changes in neurons within the extracellular matrix (post synaptic potentials)
What are action potentials?
a brief current in the axon with limited potential field
What are post synaptic potentials?
50-200 ms with greater field, likely to be origin of EEG signal
What is chronic neuronal depolarization?
Long term source and likely origin of EEG signals.
What is an Excitatory Post-Synaptic potential?
Neurotransmitters excite the neuron and lead to depolarization of transmembrane potential, dendrites. Inside of the neuronal membrane more positive, outside more negative.
What is inhibitory post synaptic potential?
local hyperpolarization located on the cell body of the neuron
What can lead to rhythmic waves such as sleep spindles?
interaction between the cortex and thalamus.
What are electrodes?
Metal discs made from gold, silver/silver chloride, tin, or platinum with low impedance, collodian may be used in LTM
What is impedance?
Resistance to current flow
How should electrodes be placed?
10-20 system typical, 10-10 system for closer electrode placement
How do potential fields affect the EEG?
Electrical fields generate in rings, with event maximal at a specific electrode and waning as it moves from the point of origin.
How does bipolar recording affect the EEG?
this recording type links successive electrodes in a chain, causing upward or downward deflections. This causes phase reversals in a potential field on the EEG>
If input one is more negative than input two, what is the deflection?
Upward
If input two is more negative than input one, what is the deflection?
Downward
Label upward and downward deflections as positive or negative.
upward- negative, downward-positive.
