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| EEG Feedback Instrument |
The instrument available is: EEG Analyser - FM515
Electrical activity in the brain, the EEG, was discovered by Berger in the late 1920s. He classified the easily-detected signals according to their frequency, giving the label Alpha to activity in the range 10 to 13Hz; the normal wakeful state yields Beta activity with a higher frequency and lower amplitude, and Theta and Delta activity are lower in frequency and associated with sleep or a state close to it.
Alpha production occurs most easily in someone who is in a state of relaxed awareness, neither drowsy nor alert. Mental activity and sleep both interfere with Alpha production, which seems to be found when the mind is blank, though conscious. Meditative trance states are associated with increased Alpha activity.
Alpha wave training has been used to reduce activity and increase attention span in hyperactive children, and for its restful recuperative value in helping a person to achieve a state of not-thinking. It seems to be incompatible with anxiety and so is used as a specific treatment for chronic anxiety. There are also reports of its successful use in pain suppression, and in the treatment of epilepsy and of obsessional neuroses.
It is attracting increasing attention among competitive sportsmen as a tool for psychological preparation for competition; successful performance seems to be associated with a state of mind which can be trained.
![[FM515]](ds5.jpg)
This is a sophisticated and powerful tool for the analysis and feedback of EEG signals. It amplifies the signals, analyses them, and provides a visual display of the amplitude of five different frequency bands. It also provides sound feedback for the presence of signals in a specified frequency band; it times for how long they are present in a timed training session, and warns of the presence of unwanted signals and of muscle activity.
It can pass data to a computer for subsequent analysis, and can switch on a cassette player to give your personal selection of feedback sound.
It represents a major advance in EEG equipment at a very reasonable price. While much more expensive than the Alpha Sensor, its microcomputer control and elaborate filter system and particularly its capacity to look at more than one frequency at a time make it technically far superior. Other multi-frequency EEG systems start at at least twice the price of this one.
The instrument is operated from 6V DC, from batteries or a mains power supply. A headband with gold-plated electrodes is supplied as standard and other electrodes can be provided. Highly discriminating filters separate the signals into the following wavebands:
Separate quantitative indicators show if electrode contact is poor and if artifact is present; only if they are not, and if the signal exceeds the adjustable threshold, can feedback be obtained. The feedback takes the form of a pleasant chirping sound, presented either through the loudspeaker or an earphone. The instrument notes the amount of time during which feedback is supplied, and at the end of the preset session time, 3 to 30 minutes, the 'score' of time above threshold is displayed digitally, alternating with the session time.
As the EMG Channel can register up to 250 µV, the instrument can also be used specifically for EMG feedback. During training, data is passed to an RS232 connector; many computers can accept such a signal.
Last Updated: 2003.05.22
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