The Measurement of Brain Waves

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The cerebral cortex is composed of neurons that are interconnected to each other in networks and also receive inputs from other areas of the brain.  Electrical activity in the form of nerve impulses being sent and received to and from cortical neurons is always present, even during sleep. Biologically, medically and legally, the absence of cortical activity signifies death.

The electrical activity you are measuring reflects both the intrinsic activity of neurons in the cerebral cortex and the information sent to it by subcortical structures and the sense receptors. This composite activity is called an electroencephalogram or EEG.


An EEG electrode will mainly detect the activity in the brain region just under it. Nevertheless, the electrodes receive the activity from thousands of neurons.  In fact, one square millimeter of cortex has more than 100,000 neurons.  It is only when the input to a region is synchronized with electrical activity occurring at the same time that you begin to distinguish simple periodic waveforms in the EEG.


Four simple periodic rhythms recorded in the EEG are alpha, beta, delta, and theta. These rhythms are identified by frequency (Hz or cycles/sec) and amplitude. The amplitudes recorded by scalp electrodes are in the range of microvolts (μV or 1/1,000,000 of a volt).


rhythm Freq (Hz) Amp(μV)














Luciana will be in Mexico City August 6th

Conciencia aumentada con neurofeedback. Arte interactivo generativo con electroencefalografía (EEG)

Luciana is giving a lecture with EEG interaction via brainmachines for CENART, at 6pm, August 6th, 2012:
5to. Encuentro Internacional Arte y Nuevas Ciencias 2012

The 5th international meeting of Art and new sciences and 2 workshops 10am -1pm on August 6th and August 7th