Time marches on
by Jay Gunkelman - December 27, 2012
As we wrap up 2012, it sure is an exciting time!
We see the rapid technological improvements in the field of EEG. It seems like only yesterday when I was working on tube-type amplifiers on Grass model I and III monstrosities as the state of the art, but these were all replaced over the years with solid state amplifiers. The older analog amplifiers from the classical "Ofner "T" type" and the Beckman Instrument line have long since been replaced with digital amplifiers. Signal processing has also improved from the days of pen alignment and baseline drift concerns of old analog EEGs, with digital techniques now able to remove artifact in ways we could not imagine in the 1970s when I started in EEG.
The amplifiers used to record the EEG have improved, with newer amplifiers showing a flat frequency response from DC to well over 100 Hz commonly now, but in the 1970s it was difficult to produce such a device, and many were unable to perform past 25 to 30 Hz. These older amplifiers were OK if you were doing 50 Hz sampling across each channel, as the Nyquist cutoff would be in the mid-20s anyway. With modern computer speeds, these old slower sampling rates are not used, and an old high frquency response of 30 Hz misses Gamma, which is a critical spectral presence if you are interested in conscious brain function. New devices allow for Gamma and even Gamma II (80-100 Hz) to be seen.
It is easy to appreciate the advances in the field, though even now some are held back by adherence to older approaches.
We are happy to be on the leading edge of the technological advances in EEG, and we will be bringing small pieces of these advances to your attention with this blog.
From my perspective, the future of EEG/qEEG has never been as bright.... we welcome in 2013 along with all the freshness a New Year's perspective holds!