Medical Electroencephalography questions

[Simfish]

SO they characterize it into alpha,beta,gamma,and delta waves. Are those just different behavioral patterns of the same wave or distinct waves that can all be seen on the same diagram? There isn't a good explanation of the electroencephalography anywhere - not in my neuroscience textbook, not on Wikipedia, they only describe what different amplitudes of each means...

 

[Taliesin]

Alpha, beta, gamma and delta "waves" are not strictly waves, but are bands of the frequency spectrum of the EEG. Different cognitive states (such as attention or sleep) tend to be associated with different proportions of power in the different EEG bands. I think the current thinking is that the EEG arises from coordinated activity across neuronal populations, and may indicate cooperation among brain areas. This link has a neat summary of the different bands (note that this link goes to a company that claims to "boost your potential" by manipulating these waves).

 

[quantumcarl]

SO they characterize it into alpha,beta,gamma,and delta waves. Are those just different behavioral patterns of the same wave or distinct waves that can all be seen on the same diagram? There isn't a good explanation of the electroencephalography anywhere - not in my neuroscience textbook, not on Wikipedia, they only describe what different amplitudes of each means...

Maybe you've seen this site. It goes into some detail regarding your thread.

Brain waves are attributed to electrical activities of the brain which are manifest as alternating potential differences at the scalp surface. When acquired through scalp electrodes, such potential differences result in time-continuous signals termed electroencephalogram (EEG). From a physical point of view, it is opportune to model the wave-like qualities of EEG as a finite sum of harmonic oscillations at discrete vibration rates triggered by a central pace-maker. Hence, brain-waves can analoguously be interpreted like sound waves in acoustics which consist of a fundamental oscillation superimposed by higher harmonics. Each of these partial tones is uniquely characterized by 2 quantities, its frequency ("pitch") and its amplitude ("loudness").
In terms of this model, brain-waves are composed of a series of "partial tones" ranging in frequency between 0.25Hz and 64Hz (7 octaves), whereby the "tonal composition" essentially depends on the state of consciousness, such as wakefulness or sleep stages.

From: http://www.bli.unizh.ch/BLI/Subhome/enceph.html

 

[PIT2]

I read somewhere that the brainwaves of less complex animals have a higher frequency than the more complex ones. What is the explanation for this?