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Source: Scientific American (October 1973)
"Auditory Beats in the Brain"
by Gerald Oster
Slow modulations called binaural beats are perceived when tones of different frequency are presented separately to each ear. The sensation may show how certain sounds are processed in the brain.
If two tuning forks of slightly different pitch are struck simultaneously, the resulting sound waxes and wanes periodically. The modulations are referred to as beats; their frequency is equal to the difference between the frequencies of the two original tones.
Binaural beats have been widely regarded as a mere curiosity. A recent textbook on hearing does not mention them at all. Yet the measurement of binaural beats can explain the processes by which sounds are located --a crucial aspect of perception. It is possible that hormonally induced physiological behavior changes may be made apparent by measuring the binaural-beat spectrum.
Source: SCIENCE, VOL. 249 (1989)
"The Mind Revealed"
by Marcia Barinaga
Some neuroscientists think that recently discovered oscillations of electrical potential at 40 hertz hold the key to how the brain assembles sense impressions into a single object.
Has Wolf Singer uncovered the cellular basis of consciousness? Some neuroscientists think he may have, although Singer himself stops short of such a bold claim.
It was in his recording that Singer noticed that, for short periods of less than half a second, the field potential was oscillating--alternately rising and dipping--with a frequency of 40 hertz. Those oscillations reflected a synchronous, repeating pattern of current flow into the neurons in the vicinity of the electrode. And since such an ion flow often triggers an action potential, that meant that many of those neurons must be firing action potentials together, in brief phase-locked synchrony.
"We think of consciousness as occurring in different ways," Crick says. "You can be conscious of pain; you can be self-conscious; you can be conscious of hearing, seeing, even of making plans. Our hypothesis is that all of these may have something in common and therefore why not study the easiest one? We think the easiest one is visual awareness."
One of the features that makes the 40 hertz oscillations attractive as a mediator of visual awareness, Koch says, is that their time scale corresponds with that of attention flitting from one object to another. The neurons typically stay phase-locked for several hundred milliseconds, which would allow them to make and break their liaisons in roughly the same period that a person's attention moves from one subject to the next.
As different subjects compete for attention, different sets of neurons may set up oscillations, Koch proposes. One wins momentarily, and attention is briefly focused. Then that oscillation fatigues and attention is directed elsewhere. "It's a very beautiful picture," he enthuses. As the experimentalists pursue the oscillations in their biological context, the theorists are cheering from the sidelines. Von der Malsburg, for one, is eagerly awaiting the next round of results. "Wolf Singer and the others are onto something extremely important," he says. "If this experimental-theoretical story materializes even further, it will open the door to a completely new era."
Source: HEALTH/SCIENCE, New Mexican April 7, 1995
"A New Theory of Consciousness"
For scientists who study the human brain, even its simplest act of perception is an event of astonishing intricacy.
40 Hz brain activity may be a kind of binding mechanism, said Dr. Rodolfo Llinas a professor of neuroscience at New York University.
Llinas believes that the 40-cycle-per-second wave serves to connect structures in the cortex where advanced information processing occurs, and the thalamus, a lower brain region where complex relay and integrative functions are carried out.
The Brain Wave Frequencies of Health
by Jean Charles Genet, Director of The National Center for Integrative Medicine and The National Research Center for Chronic Fatigue
The ability of the brain to enter and maintain certain frequencies while sleeping may determine the level of health a person experiences.
Individuals suffering from the symptoms of Chronic Fatigue (waking up tired, stressed, experiencing symptomatic pain, depression, confused thinking, memory loss, headaches, nervous stomach, or having sleeping disorders, etc.) were solicited by the National Research Center for Chronic Fatigue in Denver, Colorado.
Patients were measured by electroencephalographic (EEG) brain wave recordings. It was revealed that certain frequencies could not be maintained. Although, as with any group, the response to one measured frequency is different from one person to the next, the overall response from those tested showed seven frequencies to be consistently weaker.
These seven frequencies seemed to be guide posts within the subconscious that lead the brain into and out of specific functions necessary for the nightly reconstructive process of the body to occur while in the sleep cycle. The weakness or inability to reach and maintain these frequencies related directly to the specific symptom or ailment experienced.
REDUCTION IN LEVELS OF EXHAUSTION Those who suffer from Chronic Fatigue exhaust very easily. When moved to 4HZ these individuals showed marked improvement in the length of time between the occurrence of exhaustion after certain exercises were completed.
SOLUTIONS TO PROBLEMS At 7.5 HZ subjects who before suffered from confused thinking reported an ease at finding solutions to troublesome problems after a re-evaluation was conducted.
LESS EFFECT FROM SYMPTOMS Those individuals whose ailments have manifested into the fourth stage of Chronic Fatigue, where some form of disease is apparent, experienced a release from the negative sensation of their symptoms when moved into 1.5HZ.
NEW YORK TIMES: SCIENCE SECTION 1989
"Theta; The Gateway to Learning and Memory" |
