10-16-2008 10:01 AM
good morning to all,
i'm doing a project in EEG but i only going make it in 8 channel. there is something i dun understand that is the palcement in the brain. i have a pic below there are some location for placement. Can anyone tell me if i would like to make only 8 chanel where should i put?
what do we use for the Eref , in the amplifier. it from the electrode placement or voltage we supply in. but our brain only in mircV
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10-16-2008 11:50 AM
There is an international standard for electrode placement called the "10-20" system. It defines standard electrode placement (like your diagram) plus a series of "electrode montages" or subsets of these electrodes that are connected to the amplifier inputs in a variety of configurations depending on the number of channels that you are recording simultaneously. Some of these montages are "referential", meaning that each electrode is referred to a single common reference (like an ear, for instance), while other montages are termed "bipolar" or "chained" since the electrodes are arranged in pairs, linked one to the next (one channel's reference electrode is another channel's active electrode). When there are a small number of channels, you must use several recordings to achieve complete coverage (some "longitudinal" and some "lateral").
I really depends on what you are trying to capture during your recording. If you are doing seizure monitoring and you don't know where the seizures (or other abnormal waveforms) are likely to appear, you must have very good coverage (and lots of simultaneous channels). Seizure monitoring systems usually employ 32 more channels (many use 64 or more). If you are just monitoring EEG to determine sleep stages, alertness, or other more general patterns, then you only need a few channels (overnight sleep recordings often only use 4-8 channels of EEG).
This is a complex subject - here's a reference to a good book for further background: Link
10-16-2008 08:47 PM
steve, thanks for u comment on it! i think mayb i will need more channel for my project since my lecture wan me try to detect n capture the signal, like we think it in the mind, but it speak or display in the computer where we control it using the signal when we think.
this subject really complex and diffucult to understand well~
can u show me the pair for general analysis?