Neurofeedback is the name
given to a form of biofeedback training involving teaching subjects to
alter their own brainwaves.
Basic facts about brainwaves
Before discussing neurofeedback, it might
be as well to explain some basic facts about brainwaves. First of all,
they occur at different frequencies — some fast, some slow. Brainwaves
are classified as belonging within one of four different frequency ranges
(note that these are not, however, universally accepted definitions;
different researchers do use slightly different ranges):
- delta:
the slowest — 0-3.5 Hz — with the highest amplitude;
characteristic of deep sleep
- theta:
4-8 Hz; characteristic of a dreamy, relaxed state
- alpha:
8-12 Hz; might perhaps be best described as a state of relaxed
alertness
- beta:
13 Hz and above; this is your alert, focused mode; mentally active
Of course, these aren’t either-or
states; your brain is always producing some amount of all these different
classes of brainwave from different parts of your brain.
A variety of problems — ADHD, learning
disabilities, epilepsy, head injury, even chronic fatigue sometimes —
are associated with a higher ratio of excessively slow brainwaves (usually
theta). When this occurs in the frontal lobes, attention, concentration,
memory and emotional control are all compromised.
Neurofeedback training
Although the ability of subjects
(initially, cats!) to alter particular brainwaves has been known since the
1960s, studies until recently have tended not to be scientifically
rigorous, and a standard methodology has yet to be developed.
The absence of a scientifically validated methodology does mean
that we must regard the field with heightened critical awareness.
Nevertheless, the procedure does seem to be having a measurable and
consistent effect in certain areas, and is clearly worth pursuing.
One of the main areas in which
neurofeedback training has been utilized to apparently good effect is that
of ADHD sufferers. A number of studies have achieved similar levels of
improvement with neurofeedback training as has been achieved with drugs.
Several studies have also shown that
neurofeedback training can improve the performance of learning disabled
children, and adults with head injuries.
How neurofeedback works
What exactly is neurofeedback training
doing?
A recent study found that training to enhance the low beta
components of sensorimotor rhythm (12-15 Hz) resulted in increased
perceptual sensitivity and reduced omission errors and reaction time
variability. Training in enhancing slightly higher frequency beta waves
(15-18 Hz) was associated with faster reaction times and increased target
P300 event-related potential (ERP) amplitudes. (An event-related potential
is the brief blip that occurs when we record a new stimulus; the amplitude
of the electrical wave hits its peak some 300 milliseconds after the onset
of the stimulus. P300 ERP amplitudes are
thus a measure of the way the brain pays attention and discriminates
between potentially important and unimportant stimuli. More unusual
stimuli produce greater amplitudes. Alcoholics tend to have low P300
amplitudes, and alcoholics with a strong family history of alcoholism have
the lowest. On the other hand, those with an anxiety disorder tend to have
high P300 amlitudes.)
While training in increasing beta waves
appears to be useful for learning (particularly attentional) disabilities,
training in other brainwave changes may be appropriate for other
situations — for example, in reducing the debilitating effects of
anxiety and stress. There is some evidence that learning to raise theta
waves over alpha waves improves musical performance in stressful
conditions.
Training variables
Neurofeedback training to date has
involved training in particular fixed frequency bands, but it has been
suggested that individuals vary in their brainwave frequencies, both as a
result of age and individual variability, and that it might be more
effective to tailor training to the individual.
There is great variability in the number
of training sessions considered necessary by different researchers, perhaps because of individual
variability, perhaps because a standard protocol has yet to be
established. However it is generally agreed that a session should be 30-60
minutes long.
Interestingly, and unlike most other learning
strategies, all that is required to learn this new skill, it seems, is
feedback - letting you know what effect, if any, you are having, with
appropriate (i.e., positive or negative) reinforcement. Advice about what to do
does not seem to help particularly. Indeed, even after learning to achieve
the desired effect, many people are not sure exactly what it is they do.
Feedback is generally provided in two
forms: visual and auditory. However, there is some evidence that visual
feedback is far more important.
Web resources
International Society for Neuronal
Regulation http://www.isnr.org/
Association
for Applied Psychophysiology and Biofeedback http://www.aapb.org/i4a/pages/index.cfm?pageid=3281
References
Egner, T. & Gruzelier, J.H. 2004. EEG
biofeedback of low beta band components: frequency-specific effects on
variables of attention and event-related brain potentials. Clinical
Neurophysiology, 115(1), 131-9.
Egner,
T. & Gruzelier, J.H. 2003. Ecological
validity of neurofeedback: modulation of slow wave EEG enhances musical
performance. Neuroreport, 14(9), 1221-1224.
Fernandez,
T., Herrera, W., Harmony, T., Diaz-Comas, L., Santiago, E., Sanchez, L., Bosch,
J.,
Fernandez-Bouzas, A., Otero, G., Ricardo-Garcell, J., Barraza, C., Aubert,
E., Galan, L. & Valdes, R. 2003. EEG and behavioral changes following neurofeedback
treatment in learning disabled children. Clinical
Electroencephalography, 34(3), 145-52.
Fuchs, T., Birbaumer, N., Lutzenberger,
W., Gruzelier, J.H. & Kaise, J. 2003. Neurofeedback
Treatment for Attention-Deficit/Hyperactivity Disorder in Children: A
Comparison with Methylphenidate. Applied Psychophysiology and Biofeedback,
28 (1), 1-12
Gruzelier, J. & Egner, T. 2005.
Critical validation studies of neurofeedback. Child & Adolescent
Psychiatric Clinics of North America, 14(1), 83-104, vi.
Hammond, D.C. An introduction to
neurofeedback. http://neurofeedbacktoday.com/intro2nf.pdf
Holtmann, M., Stadler, C., Leins, U., Strehl,
U.,
Birbaumer, N. & Poustka, F. 2004. [Neurofeedback for the treatment of
attention-deficit/hyperactivity disorder (ADHD) in childhood and
adolescence] Z Kinder Jugendpsychiatr Psychother, 32(3),
187-200.
Orlando, P.C. & Rivera, R.O. 2004.
Neurofeedback for elementary students with identified learning problems.
Journal of Neurotherapy, 8(2), 5-19.
Rossiter, T.
2004. The Effectiveness of Neurofeedback and Stimulant Drugs in Treating
AD/HD: Part I. Review of Methodological Issues. Applied Psychophysiology
and Biofeedback, 29 (2), 95-112
Rossiter, T.
2004. The Effectiveness of Neurofeedback and Stimulant Drugs in Treating
AD/HD: Part II. Replication. Applied Psychophysiology and Biofeedback, 29
(4), 233-243
Siniatchkin, M., Kropp, P. & Gerber,
W-D. 2000. Neurofeedback—The
Significance of Reinforcement and the Search for an Appropriate Strategy
for the Success of Self-regulation. Applied Psychophysiology and
Biofeedback, 25 (3), 167-175.
Vernon,
D., Egner, T., Cooper, N., Compton, T., Neilands, C., Sheri, A. & Gruzelier, J. 2003.
The effect of training distinct neurofeedback protocols on aspects of
cognitive performance. International Journal of
Psychophysiology, 47(1), 75-85.
Vernon, D., Frick, A. & Gruzelier, J.
2004. Neurofeedback as a treatment for ADHD: A methodological review with
implications for future research. Journal of Neurotherapy, 8(2), 53-81.
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