Literature Review of Auditory and Visual StimulationDr. Emily L. Stevens, Ph.D., LPC - Neurobehavioral Consulting
History and Development of Auditory Visual Entrainment
The newest wave of therapies involves non-drug interventions capable of rapidly healing previously resistant pathologies and improving cognitive performance in normal subjects.
The new interventions have arisen out of ongoing research in psychophysiology, electroencephalographic (EEG) biofeedback and QEEG patterns that have been associated with various disorders and psychopathology. For example, in the sixties, EEG feedback was used primarily to promote relaxation and control stress and in the late seventies and early eighties focused on increasing attention in patients with learning problems (Ochs, 1993). However, interest in the effects of light stimulation and brainwaves began hundreds of years prior to the sixties. Visual and auditory stimulation specifically has a significant history that dates back to early medicine and science. In the early stages of research the photic (visual) aspect and the auditory aspect of treatment were utilized and researched separately. The first known documented experimentation with photic stimulation was by Ptolemy c.200 A.D. While watching a spinning spoked wheel in the sun, he noted that the flickering light caused patterns and colors to appear before his eyes (Siever, 2000).
In the seventeenth century there was resurgence and renewed interest in research on photic stimulation. This research examined the frequency at which individual flickering light began to “fuse” into what is defined as the steady light. The phenomenon known as “flicker fusion” was first established in 1834-1835 by the Englishman, Talbot and by the Belgian named Plateau, whose paper is considered a landmark and significant contribution in the field of photic stimulation. They noted that healthy people could notice flickering of light at a higher frequency than a person experiencing ill health could. Then Pierre Janet, a French psychiatrist, found in the late 1800’s reduction in hysteria and an increase in relaxation when he exposed psychiatric patients to flickering light that was delivered by a rotating strobe-wheel illuminated by a lantern. The patients were asked to stare into the strobe-wheel for treatment. This was the first known clinical application using photic stimulation as a treatment tool and protocol (Siever, 2000).
Research continued in this area within clinics and hospitals well into the mid-1900. For example by 1940, James Toman performed a number of simple studies into the effects of flicker or photic stimulation on the flicker potentials of the brain. He studied and recorded the percentage of time that alpha was produced with the eyes closed and the effects that entrainment or stimulation could impact an individuals natural brain wave levels. Toman was able to confirm previous work, which showed that people with strong alpha rhythms had a poor range of entrainment, and those with little or no alpha rhythms could be entrained to a wider range of frequencies. He also observed that the cerebral frequency of stimulation seemed to maintain itself for a period of time following the end of flicker stimulation and he hypothesized that this was due to the mutual interaction of neurons (Toman, 1941). In 1959, Dr. William Kroger and Sidney Schneider reported that the rhythmic flashing of the dot on radar screens of ships and submarines caused some radar operators to readily enter into a relaxed state of mind and others to fall into deep hypnotic states. The conclusion was that these men were being visually stimulated at a frequency near the frequency that the brain was producing. This prompted the creation of a piece of EEG equipment called the “Brain Wave Synchronizer” which was created by Sidney Schneider and tested on approximately 2,500 patients and subjects, some in groups and some individually creating hypnotic states (Kroger, 1959). Later in 1959, John Barrow, MD, from MIT, studied the effects of random photic stimulation on the EEG of patients and confirmed Bartley’s earlier observations (Siever, 2000). Also in 1959, Chatrian and his colleagues at the Rochester State Hospital utilized depth-electrode recording to observe the brain’s response to clicks in either or both ears. They observed an auditory evoked response to clicks at 3 Hz or less. At click rates of 15 Hz, they observed auditory driving effects in the EEG on the brain (Chatrian, 1960).
Then beginning in the 1960’s new generations of EEG equipment became available and computers became faster, researchers developed an expanding understanding of brain wave patterns by utilizing computer based digital EEG techniques. Clinical connections were identified between specific patterns of brain wave activity and pathological, normal, and optimal cognitive performance/states. Research began to skyrocket in the EEG arena.
In 1963, M.S. Sadove, MD, Director of Anesthesiology at the University of Illinois, reported that by using the Brain Wave Synchronizer, photic stimulation put over 90 % of his patients into a trance, which reduced the amount of anesthesia needed for surgery. Sadove believed hypnosis was so powerful that some day many of our drugs might be forgotten or no longer needed (Siever, 2000).
Bernard Margolis, DDS, published an article in 1966 using the Brain Wave Synchronizer to induce hypnosis during dental procedures and decrease post dental procedure complications. He noted that the patients required less anesthesia, had greater control of gagging, less bleeding, and their fear and anxiety was sharply reduced during the dental procedure concluding a positive response to photic stimulation and hypnosis (Margolis, 1966).
Gerald Oster continued the work in the area of auditory stimulation and published an article on the effects of binaural beat auditory stimulation in Scientific American in 1973. He demonstrated the difference between monaural beats and binaural beats, as they are perceived when mixed with other tones (Oster, 1973). Also in 1973, Kinney and her colleagues, at the Naval Submarine Research Laboratory in Connecticut, developed the first successful mathematical model to determine the visual evoked response at frequencies of 4 Hz and higher that has proven to be incredibly accurate (Kinney, 1973).
Several studies performed by neurosurgeon Norman Shealy, M.D., and his associated have shown that cranial electro-stimulation produces rapid and significant increases in serotonin levels. They have also found that ten minutes of photic stimulation produced significant and almost instantaneous increases in serotonin and other biochemicals such as growth hormone, melatonin, oxytocin, beta-endorphin, and luteinizing hormone (Shealy, Cady, Cox, Liss, Clossen, Veehoff, self-published).
Then in the 1980s, Norman Shealy and colleagues studied the effects of 30-minute sessions of 10 HZ photic stimulation. Blood levels of serotonin, endorphin, melatonin, and norepinephrine were taken regularly. They identified a drop in the daytime level of melatonin and substantial increases in levels of endorphin, serotonin and norepinephrine. Shealy’s group theorized that an increase in beta-endorphins is associated with a sense of well being, happiness and decreased pain. The increase in norepinephrine and serotonin and the decrease in melatonin suggested an increase in alertness and awareness. They also noted that people had a more positive relaxation response to photic stimulation than from using self-hypnosis, cranioelectrical stimulation or “Hemi-Sync” tapes from the Monroe Institute (Cady & Shealy 1990).
In 1989, Anderson, of the Queen Elizabeth Military Hospital, performed treatment on patients with migraine headaches. All seven subjects in the study experienced one or more migraine related symptoms such as: aura, photophobia or periodic vomiting. And no subject had positive medication response. The subjects were instructed to use auditory visual entrainment at the onset of a migraine. Out of the 50 migraines reported, 49 were rated being helped and 36 of the 49 were rated as being “stopped”. One of the most important aspects of the treatment was in regards to post treatment pain. Pre-treatment migraines on average lasted six hours while post-treatment migraines lasted an average of 35 minutes revealing a significant difference in debilitation from the headaches (Anderson, 1989).
Boersman and Gagnon, at the University of Alberta, published a study in 1992 utilizing DAVID Paradise AVE equipment to treat chronic pain. The study involved three back pain injury subjects and measured pain medications used, suicide ideation, anxiety, self-esteem, hopelessness, coping ability and family stability. The results indicated a decrease in symptoms and the need for pain medication (Boersman, 1992).
Work continued in the 90’s with many papers and research projects focused on the use of AVE for a variety of clinical disorders and learning deficits. For example, in 1993, Russell and Carter conducted a study on a group of learning disabled boys between 8 and 12 years of age. The boys were given 40 sessions of AVE stimulation at 10 Hz and 18 Hz and showed an average IQ increase of 8 points on the Raven IQ test and significant improvement (<. 01) in memory, reading and spelling.
Noton presented findings in 1995 and 1996 at the AAPB Annual Conference for a study on pre-menstrual syndrome performed by Anderson from the Postgraduate Medical School in London. The study noted that PMS appears to be a “slow brainwave” disorder and falls into the group of disorders including, Attention Deficit Disorder, Chronic Fatigue Syndrome, and Minor Head Injury. “Of the seventeen women who completed the study, 76% experienced a greater than 50% reduction in their PMS symptoms.” The study indicated the possibility that these results may reflect that AVE may be impacting mostly by increasing cerebral blood flow rather than increasing brainwaves activity level (Noton, 2002).
In 1999, Frederick, Lubar, Rasey, Brim and Blackburn completed a study of the effects of 18.5 Hz AVE on 15 college student’s performance. The entraining effect at CZ was measured and the results concluded that entrainment produced the largest brainwave increases at 18.5 Hz. The study also concluded that eyes closed produced better audio and visual entrainment and that combined audio and visual entrainment may not be as effective as individual sensory stimulation (Frederick et al., 1999).
Trudeau studied the effects of 18 Hz stimulation, in 1999, using the DAVID Paradise Jr. with 15 people diagnosed as suffering from Chronic Fatigue Syndrome. Trudeau concluded that this syndrome showed an unusual EEG consisting of high occipital and parietal beta activity in nine of the 15 participants. 60 sessions of AVE revealed a significant reduction in depression (BDI from 17 to 9) and decreased impulsivity when measured on the TOVA continuous performance test (Trudeau, 1999).
There is another advantage to AVE and EEG neuro-feedback over standard medical treatment, which mainly consists of pharmaceutical medications, is that it is a non-invasive treatment for changing brain functioning.
For example, beta-endorphin has been linked to internal control mechanisms for eating and ethanol consumption (Peniston, & Kulkosky, 1989). Based upon an existing literature, Peniston and Kulkosky observed, “If Beta-endorphin is elevated in alcoholics, a return to consumption of ethanol calories would be inevitable” (Peniston & Kulkosky, 1989). Peniston and Kulkosky did find significantly elevated levels of beta-endorphin in the group who received traditional medical treatment. They did not find elevated levels of beta-endorphin in the group who received the brain-wave training. This continues to support that mind technology based treatments actually change brain chemistry and hormones toward healthier levels.
There have been several groups that have compared the effectiveness of AVE to EEG neuro-feedback. Russell, and Carter, has used LS brain-wave training with learning disabled (LD), and ADHD children for increased beta brainwave training (Russell & Carter, 1993). Russell has indicated that he believes that the AVE is just as effective as EEG neuro-feedback for brainwave training. Russell and Carter suggest that use of LS devices and EEG training “may stimulate either the successful establishing of new neural pathways in the brain or re-establishing of old pathways that have been disrupted.”
Brain wave biofeedback techniques are presently being used successfully in the operant conditioning of specific frequency bands. The principle of using sensory stimuli to entrain specific cortical rhythms through the frequency-following response is well documented and recognized as a successful tool for treating some disorders (Gerken, Moushegian, Stilman, & Rupert, 1975; Neher, 1961).
By utilizing identified EEG clinical research patterns EEG biofeedback researchers have been training subjects who have frequency patterns associated with various disorders to alter their brain wave patterns to match those associated with normally functioning individuals (Hutchison, 1990). Auditory visual entrainment and EEG neurofeedback have been found to be an effective intervention for many severe and resistant disorders including, “depression, sleep disorders, seizures, chronic fatigue, headaches, mood swings, anxiety” (Hutchison, 1990), alcoholism, (Peniston & Kulkosky, 1989), addiction, attention deficit hyperactive disorder (ADHD), epilepsy, post-traumatic stress, paralysis and cognitive impairment as a result of a stroke or head injury (Ochs, 1993).
Effects of Binaural (auditory) Stimulation and Entrainment
Binaural-beat signals utilize a powerful form of audio or sound driving to alter brain-wave frequencies. The German scientist H.W. Dove first observed binaural beat signals in 1839. In its simplest form binaural signals consist of two pure tones of different pitch being presented to each ear. Before the advent of electronic oscillators, researchers used tuning forks to produce the tones. A subject can hear monaural beats or one tone with just one ear. Monaural beats are the sounds that can be heard by the ears in the room. Binaural beats occur when the tones are presented separately to each ear. The sound no longer waxes and wanes in the room, but is heard inside the subject’s head as a tone synthesized by the brain which does not exist outside of the subject’s head (Oster, 1973, Carter, 1998).
The human ability to “hear” binaural beats appears to be the result of evolutionary adaptation. Many evolved species can detect binaural beats because of their brain structure. The frequencies at which binaural beats can be detected change depending upon the size of the species’ cranium. In the human, binaural beats can be detected when carrier waves are below approximately 1000 Hz (Oster, 1973). Below 1000 Hz the wavelength of the signal is longer than the diameter of the human skull. Thus, signals below 1000 Hz curve around the skull by diffraction. The same effect can be observed with radio wave propagation. Lower frequency (longer wavelength) radio waves (such as AM radio) travel around the earth over and in between mountains and structures. Higher-frequency (shorter wavelength) radio waves (such as FM radio, TV, and microwaves) travel in a straight line and can’t curve around the earth. Mountains and structures block these high-frequency signals requiring high towers for them to travel back and forth from. Because frequencies below 1000 Hz curve around the skull, incoming signals below 1000 Hz are heard by both ears. But due to the distance between the ears, the brain “hears” the inputs from the ears as out of phase with each other (Oster, 1973). As the sound wave passes around the skull, each ear gets a different portion of the wave. It is this waveform phase difference that allows for accurate location of sounds below 1000 Hz. In summary, it’s the ability of the brain to detect a waveform phase difference is what enables it to perceive binaural beats.
When signals of two different frequencies are presented, one to each ear, the brain detects phase difference between these signals. Under natural circumstances a detected phase difference would provide directional information. The brain processes this anomalous information differently when these phase differences are heard with stereo headphones or speakers. A perceptual integration of the two signals takes place, producing the sensation of a third “beat” frequency. The difference between the signal waxes and wanes as the two different input frequencies mesh in and out of phase. As a result of these constantly increasing and decreasing differences, an amplitude-modulated standing wave –the binaural beat – is heard. The binaural beat is perceived as a fluctuating rhythm at the frequency of the difference between the two auditory inputs. Evidence suggests that the binaural beats are generated in the brainstem’s superior olivary nucleus, the following response originates from the inferior colliculus (Marsh, & Brown, Smith, 1975, Atwater, 1997). This activity is conducted in the cortex where it can be easily recorded by scalp electrodes. This perceptual phenomenon of binaural beating and the objective measurement of the frequency-following response (Hink, Kodera, Yamada, Kaga, & Suzuki, 1980) suggest conditions, which facilitate entrainment of brain waves. “The subjective effect of listening to binaural beats may be relaxing or stimulating, depending on the frequency of the binaural-beat stimulation” (Atwater, 1997). Binaural beats in the delta (1 to 4 Hz) and theta (4 to 8 Hz) ranges have been associated with reports of relaxed, meditative, and creative states (Hiew, 1995), and used as an aid to falling asleep. Beats in the alpha frequencies (8 to 12 Hz) produce increased alpha brain waves associate with relaxation (Foster, 1990) and binaural beats in the beta frequencies (typically 16 to 24 Hz) have been associated with reports of increased concentration or alertness (Monroe, 1985) and improved memory (Kennerly, 1994).
If the difference between the two tones matches a particular brain wave state, such as 4-8 Hz (Theta), then the overall brain activity will tend to match that frequency, and hence enter that brain wave state. The phenomenon is referred to as the Frequency-Following Response or FFR and is a powerful form of brain-wave entrainment (Edrington, & Allen, 1985). The FFR can easily take a subject into Beta, Alpha, Theta, or Delta brain wave states and helps them maintain those states.
Existing research has shown that teachers who have played binaural beat signals in their classrooms have reported a decrease in student distractibility and an increase in academic performance (Owens, 1984). A study conducted with an introductory psychology class found significantly higher scores in the experimental group on five of six tests (Edringon 1985). Another study conducted at a government training center found an increase in scores by 30% for Morse code students (Waldkoetter, 1982a) and 75% on mental-motor skills (Waldkoetter, 1982b) using binaural beat signals in addition to standard teaching procedures. The US Army reported positive results in using binaural beat signals, in this case to improve acquisition of a second language (Pawelek & Larson, 1985). They found that it increased the ability to learn language faster and increased performance. The findings of continued research indicate that binaural beat signals are an effective and worthwhile intervention for improving a student’s educational level functioning.
The results support the ability of binaural beat stimulation to function as an effective stand-alone form of brain-wave training or mind technology. The research does provide support for the observations of teachers who have reported increased grades and fewer behavioral problems with their students while utilizing binaural-beat audio in the classroom.
The data is able to support the conclusions of previous research that binaural-beat audio signals increase a subject’s ability to perform free recall tasks, attend (reduced student distractibility) and persevere at routine tasks (as measured by the Digit Span and Digit Symbol subtests); three important dimensions for success in the classroom.
Effects of Photic (Visual) Stimulation and EntrainmentInterest and research in visual brainwave response and brainwave entrainment is not new. As early as 200 AD, Ptolemy experimented with photic stimulation by spinning a spoked wheel into the sun and reported the apparent immobility of the wheel radius at a certain speed. He also noted the flickering caused patterns and colors to appear before the eyes accompanied by an added sense of euphoria, which was later identified as the “flicker fusion phenomenon”. Talbot and Plateau wrote their thesis on this phenomenon, which is described as a landmark in this field photic stimulation and response (Siever, 2000).
Photic stimulation began to be recognized again in 1895 when the illusion of colors produced by flickering light were demonstrated by Benham through the invention of what is called the “artificial spectrum top”. Then in the early 20th century, the French psychologist, Pierre Janet, noted a reduction in hysteria and an increase in relaxation with his patients when exposed to flickering light (Siever, 2000).
The effects of photic stimulation on brain wave activity were finally clarified and documented in 1946 by Walter, Dewey and Shipton. They introduced the electronic stroboscope to psychophysiological and EEG research. Thousands of subjects were exposed to intense flickering white light and all reported visual sensations of pattern, movement and color. Some individuals reported the impressions, which were particularly visually intense but only at specific frequencies. Dr. W. Grey Walter published this work in the scientific journal, “Nature” in April, 1956 and since then, hundreds of research articles have been published in various medical journals demonstrating brain wave responses to light and sound stimulation (Siever, 2000).
Clinical photic stimulation and entrainment is a noninvasive, painless, and passive form of biofeedback or EEG neurofeedback. The patient sits in a comfortable chair wearing dark glasses that have a set of tiny lights mounted on the lenses.
The research supports that the way in which visual information travels from the eyes to the brain is different from the way sensory and motor information travels to the brain. The eyes are wired so that the left visual field of our total vision for both eyes goes to the right side of the brain and the right visual field goes to the left side of the brain. The visual neural pathways in humans begin with the rods and cones, located at the back of the eye and end at the visual cortex, located at occipital in the back of the brain. The visual signals travel from the rods and cones through two to four synapses, which are nerve cell connections that are located behind the retina. The nerve impulses from the ganglion cells leave the eye via the optic nerve. During the process some visual analysis has already taken place, which delays the visual signal for a few milliseconds. The nerve impulses from each eye travel through the optic nerve, which consists of approximately one million nerve fibers and ends at the brain. The optic nerve from each eye splits into the optic chiasm which is the nerve network that routes the visual images from the visual fields of both eyes to a nest of neurons called the lateral geniculate and on to the visual cortex. This means that visual input seen in both visual fields of each eye goes to both the left and right side of the brain (Carter, 1998).
The geniculate cells are attached physically and by synapses to the thalamus, the brain’s main sensory coordinator or “gateway”to the brain. Photic stimulation evokes potentials into the thalamus. The thalamus relays sensory information into the neo-cortex and the visual impulses are then distributed into the neo-cortex. This produces more brainwave entrainment at the frontal and central areas of the brain rather than in the visual cortex. This works well for most low arousal disorders with medical applications or diagnosis because most arousal and dysfunctional disorders involve the frontal and central areas of the brain.
Each and every flash of light that enters the eye imprints itself on the rods and cones, which in turn evokes a response in the optic nerve. The electrical firing from the optic nerve stimulates the primary visual cortex, which creates a response known as the visual evoked response. It is at this point where the many individual visual evoked responses become the cortical frequency following response (Edrington & Allen, 1985). In other words, the response of the brain is to follow the frequency of the stimuli. This frequency following response is now usually referred to as brainwave entrainment or audio-visual entrainment (AVE) as cited previously.
Research clearly indicates the possibility of entraining specific frequencies of brain waves by presenting subjects with frequency-specific flickering lights (Arnibar & Pfurtscheller, 1978; Nogawa, Katayama, Tabata, Ohshio, & Kawahara, 1976; Regan, 1996; Williams & West, 1975; Yaguchi &Iwahara, 1976). For example, alpha-frequency brain waves may be entrained by exposing subjects to a light stimulus flickering at a rate within the alpha frequency range. The tendency for the electrical rhythms of the brain to become entrained to frequencies of sensory stimuli in the environment is called the frequency-following response (Moushegian, Rupert, & Stillman, 1978; Sohmer, Pratt, & Kinarti, 1977; Stillman, Crow, & Moushegian, 1978).
In 1985 G.D. Solomon reported in Headache, a peer-reviewed journal, on a preliminary study of flashing light as a treatment for muscle contraction headaches. He used a device that flashed in both eyes simultaneously at slow frequencies in the range of 1 to 3 HZ and his study showed a high level of effectiveness, even though the patients were treated for only five minutes per session. Fourteen out of fifteen patients with acute muscle contraction headaches reported complete relief of their headaches. However, migraine suffers did not appear to benefit.
Independently, D.J. Anderson developed a flashing light device for migraine, which flashed alternately in left and right eyes. With this device he achieved considerable success with migraine patients, using the device mainly in the higher part of the frequency range between 20-50 Hz. In a preliminary study, also published n Headache, Anderson reported that out 50 migraine patients, headaches 30 had significant differences in frequency and intensity as well as some “stopped”. The median duration of headaches was reduced in all patients and the interval between migraines headaches appeared to be increased. The patients utilized the device for 30 minutes to terminate a headache, though subsequent work appeared to indicate that 15 minutes per day was effective for prevention (Anderson, 1989).
In the late 1980’s, Russell and associates performed extensive studies of the effects of flashing light combined with synchronous sound on the performance and intelligence scores of boys with attention deficit disorder. Their flashing light protocol was quite unusual: the lights flashed synchronously in both eyes at a frequency of 10 Hz for two minutes, then were turned off for half a minute, then flashed at 18 Hz for two minutes, and then were turned off again for half a minute. This sequence was repeated five times, for a total of 25 minutes. These trials, published in The Texas Researcher, showed significant increases in intelligence measures (Siever, 2000).
The most carefully executed study of flashing light treatment to date was a trial of flashing light for premenstrual syndrome by D.J. Anderson and his colleagues at The Royal Postgraduate Medical School, Hammersmith Hospital, London, reported in The Journal of Obstetrics and Gynecology, 1997. In an open study 17 women with confirmed, severe, and long-standing PMS were treated with photic flashing lights for 15 minutes a day for three months.
The flashing light device consisted of a foam-covered mask, which covered the eyes shutting out all light. Mounted in the mask were red LED lamps, one in front of each eye, which flashed alternately in left and right eyes. The device was portable and designed to be used by the patient at home. The brightness of the light and the frequency of flashing were controlled by the patient, with ranges of approximately 10 to 45 mce and .5 to 50 Hz respectively (one frequency cycle consisting of light in the left eye for half the cycle and then light in the right eye for half the cycle). The patients were instructed to start at the brightest setting and at the flicker-fusion point (around 30 Hz) and then to adjust the brightness and frequency for best comfort. The patients were asked to use the device for 15 minutes per day, every day throughout their menstrual cycle . They recorded their symptoms daily for two menstrual cycles before treatment, three cycles during treatment, and one cycle after treatment was stopped. The seventeen women experienced a median reduction in their PMS symptoms of 76%. At end of trial twelve of the women could no longer be considered to have PMS. This level of improvement is greater than that reported for any other PMS treatment, be it fluoxetine (Prozac), hormones, relaxation, or vitamin and herbal supplements.
Clearly the use of photic stimulation has significant clinical uses for a variety of disorders and warrants continued research as non-invasive brain wave treatment tool.
Relationship of Study to Current Literature
EEG-slowing is associated with symptoms such as anxiety, depression, irritability, fatigue, hyperactivity, distractibility, mood swings, confusion, disorganization, sleep disorders, concentration, reading comprehension, memory, and attention. The increase in low-frequency brain wave activity is a typical pattern that has been observed in many chronic health problems.
Some researchers believe that EEG-slowing occurs when the integrating function of the brain’s cerebral cortex is blocked. All the symptoms of depression identified above are associated with slower brain waves, or what is called EEG-slowing.
AVE has been used to improve grades and grade-point averages in college students (Budzynski, Jordy, Budzynski, Tang, & Claypoole, 1999). It has been used to induce relaxation (Manns, Miralles & Adrian, 1981; Morse & Chow, 1993), hypnotic states (Kroger & Schneider, 1959; Lewerenz, 1963; Margolis, 1966) and dissociation (Leonard, Telch & Harrington, 1999). AVE has been used clinically to reduce chronic pain (Boersma & Gagnon, 1992), to treat migraine headaches (Anderson, 1989), and to treat depression (Kuano, Horie, Shidara, Kuboki, Suematsu & Yasushi, 1996). As a treatment it has produced significant reductions in anxiety and has been used as a treatment for low-arousal brain disorders such as pre-menstrual syndrome (PMS) (Noton, 2002), chronic fatigue syndrome (Trudeau, 1999), fibromyalgia (Berg & Siever, 2000) and seasonal affective disorder (Berg & Siever, 2000). Low arousal brain disorders are disorders that can be characterized by abnormal EEG patterns. ADHD is recognized as one of these disorders (Noton, 2002; Carter & Russell, 1992). Carter & Russell (1992) conducted a pilot study using AVE to treat learning and attention disorders. The results revealed improvement in IQ scores and behavior. Russell (1997) stated that AVE achieves the same results as EEG neurofeedback but at less cost and in less time, which is more treatment and patient friendly.
The beneficial effects of brain tools can also be explained by this paradigm: the devices produce changes in brain and body chemistry that can ameliorate symptoms. The major difference is that instead of producing biological changes by putting some synthetic substance into the brain and body, mind machines seem to stimulate the brain/body naturally to produce the biological changes. Since there is no synthetic substance entering the system, there is little chance of producing harmful or upsetting side effects, or of producing addiction. In that sense, the use of brain tech to naturally produce biochemical changes seems preferable to the use of pharmaceuticals.
But changes in biochemistry are only a part of a wide spectrum of psychobiological effects produced by AVE. It’s been well established, for example, that various types of brain technology ranging from flickering lights to binaural beats to EEG feedback produce rapid and profound changes in brainwave frequencies. It has also been well established for decades that a variety of disorders are linked to abnormal brainwave activity. The use of mind tools for brainwave “entrainment” or “driving” has enabled therapists to produce increased brainwave activity in desired ranges and thereby to “normalize” formerly abnormal brainwave activity and associated disorders.
Research has also shown that if a person’s brain does not seem to entrain to the frequencies being presented it does not mean that the individual will not benefit. Studies show that photic stimulation increases cerebral blood and production of neurotransmitters regardless of whether or not it changes the baseline brainwave frequencies, with each aspect playing a different part in the overall AVE experience (Fox & Raichle, 1985, Fox, P., Raichle, M., Mintum, M. & Dence, C., 1988).
A study by Dr. Walton and associates in 1992, presented at the Second International Symposium on Serotonin, showed that increased serotonin metabolism is associated with superior job performance and leadership ability. This may be the reason people that suffer from depression have commented that AVE has reduced their depression. Whatever the reason, all the participants suffering from pain in a chronic pain study by Dr. Boersma in 1992, had substantial decreases in their depression, drug usage and suicidal ideation plus an improvement in their quality of life within one year after using white light AVE stimulation.
Fox and Raichle’s 1985 study showed that cerebral blood flow in the visual cortex increased by 29% at 7.8 Hz. The increases were primarily in the visual cortex and don’t occur frontally, although whole brain oxygen metabolism was shown to have increased by 5%. This indicates that blood flow increases in that particular area may help reduce visual processing problem associated with birth defects or occipital head injuries. An interesting point about photic stimulation is that it produces maximal increases in cerebral blood flow at 7.8 Hz, the Schumann Resonance frequency (the frequency that electro-magnetic radiation circles the earth). Some researchers have indicated that the neo-cortex functions in harmony with the earth’s Schumann Resonance as we do with other rhythms in nature. Revealing that we are more connected than we realize to the earth’s vibrations and frequencies.
Fox’s 1988 paper indicated a 50% increase in cerebral visual cortex blood flow and increased glucose uptake with little changes in oxygen consumption during photic stimulation, as measured with positron emission tomography (PET). Sappey-Mariner’s research paper of 1992, using magnetic resonance imaging, showed increased cerebral visual cortex blood lactate, indicating non-oxidative glucose consumption by an average of 250% in the first six minutes of 2 Hz photic stimulation. Fox also indicated that there was an overall 5% increase in whole brain oxygen metabolism.
It is clear from many years of research and more advanced technology that AVE warrants continued research as a viable treatment adjunct or alternative.
Copyright © 2002, Dr. Emily L. Stevens, Ph.D., LPC., Neurobehavioral Consulting. All rights reserved. Many thanks to Dr. Stevens for her kind and generous permission to present this literature review, and for her invaluable clinical experience and technical advice, without which this site would not be possible.
