EEG
EEG is a test of neural function, not structure.
It records electrical activity from the cortex.
An EEG is more likely to show abnormalities.
Used in epilepsy, coma, diffuse encephalopathies, CJD
Not useful for headache, dizziness, psychiatric disorders, posterior fossa disorders
reflects net effect of synaptic activity (EPSPs and IPSPs in pyramidal neurons, not action potentials) in pyramidal neurons
graphs voltage vs time
multiple electrodes: at least 21, but can be many more
record 30 minutes of time
- a normal EEG, or repeated ones, don't exclude epilepsy, as you need to catch the seizure
huge range of normal expression - different ages; awake versus drowsy
alpha - 8-13 Hz
beta - greater than 13 Hz
theta - 3.5-7.5 Hz - occurs during sleep onset
delta - 3 Hz or less - occurs during deepr sleep