Correlates in Cerebral Function:
überaus spannende Theorie zum Thema 40 Hz-Wellen,
mit zahlreichen Ableitungen und neuen Sichtweisen auf
and Clinical Implications for Neurofeedback Training
Marvin W. Sams, Th.D., R. EEG T., QEEGT., L.A
cortical and subcortical areas of the brain have spontaneously
occurring 3644 Hz ('40-Hz") activity. Across the
scalp, the EEG peak frequency of 40 Hz is z 39.5 Hz.
A theory is proposed in which the brain has certain
resident resonant frequencies that are subharmonics
of 40-Hz activity. Some of these EEG frequencies are
commonly trained in neurotherapy.
examples are 12-15 Hz and 7-8 Hz activity, which are
third and fifth subharmonics. Other frequencies with
known cognitive and mental processing relation ships
and mathematical associations to 40 Hz include 'Frontal
mid Theta" at 6.5 Hz (sixth subharmonic) and Theta
at 4 Hz (tenth subharmonic).
40 Hz and its sub harmonics may provide further insight
into the mechanics of the neurofeedback process and
lead to more effective and efficient training. It is
also anticipated that if the concept of 40-Hz subharmonics
is explored, the mechanisms of cerebral function might
be better understood.
to the availability of the Quantitative (computerized)
EEG, the recording of high frequency (over 30 Hz) electroencephalographic
(EEG) frequencies could only be done with oscilloscopes
or with special EEG amplifiers (often non-commercial)
and fast paper speed. Oscilloscopes do not lend themselves
to the permanent and reproducible recording requirements
of researchers; recording the EEG with fast paper speed
requires a major financial expenditure for chart paper
and record storage.
Quantitative EEG (QEEG) does allow the recording of
high frequency EEG data and the ability to maintain
retrievable recordings. However, most EEG clinicians
and researchers use a sampling rate of 128 Hz (cycles
per second), restricting the high frequency response
to 32 Hz. Also, if higher sampling rates are used, very
slow (Delta) EEG frequencies are not recorded. As a
result, pathology might be missed clinically, and traditionally
reported EEG data are not available for scientific evaluation
and publication. As a result of these technical limitations,
frequencies above 30 Hz have received little attention
in either clinical or research EEG.
Laureate Francis Crick, codiscoverer of the structure
of DNA, has recently turned his attention to the brain.
In a video recorded interview (The Brain: Our Universe
Within), Professor Crick states that he believes
that 40-Hz pulses control visual mechanisms in the brain.
When we focus, certain neurons fire in a particular
pattern (40 Hz) that create a phase lock with neurons
in other areas of the cortex. He amplifies his speculations
in his recent book, The Astonishing Hypothesis: The
Scientific Search for the Soul (Crick, 1994).
hearing Crick's comments, I remembered reading or hearing
about 40Hz EEG biofeedback several years ago. Rummaging
through my library, I finally found a reference under
"Beta-Wave Training" in The Future of the
Body by Michael Murphy (Tarcher, 1992). Running
the references, I wasamazed to find a large volume of
scientific data regarding 40-Hz EEG and 40-Hz EEG biofeedback
his book, Crick erroneously credits German researchers
for the work behind 40Hz activity and even makes it
seem as if 40Hz is a new idea. While the Germans have
made important contributions, the early research, theory,
and biofeedback work on 40 Hz was done by Americans
in work dating back 30 years
strikingly meticulous research, psychophysiologist Daniel
Sheer and a variety of associates have studied a narrow
EEG frequency band that centers near 40 Hz (Sheer, 1967,
1970, 1972, 1973, 1974; Sheer & Grandstaff, 1970;
Sheer, Grandstaff, & Benignus, 1966; Sheer &
Hix, 1971). Sheer's research found frequencies in the
range of 40 Hz (36-44 Hz) in various zones of the rhinencephalon,
specifically the olfactory bulb, prepiriform cortex,
and amygdala. Rowland (1968) found 40-Hz activity with
conditioned stimulus in the ectosylvian and lateral
cortex, medial geniculate, reticular formation, center
median thalamus, and hippocampus. More recently, these
oscillations were found to be present in the motor and
visual cortex (DeFrance & Sheer, 1988).
to Sheer, 40-Hz activity reflects a focused arousal
associated with memory and learning processes. In his
words: "...40-Hz reflects repetitive stimulation
at a constant frequency for a limited time over a limited
circuitry. The circuitry is defined behaviorally by
the spatial-temporal patterning of sensory inputs, motor
inputs, and reinforcement contingencies. It is 'optimal'
for consolidation because repetitive synchronous excitation
of cells maximizes the efficiency of synaptic transmission
over the limited circuitry." (Sheer, 1975, p.
356) He bases his conclusions on studies in which he
found 40-Hz activity during visual acquisition of a
visual discrimination in cats (Sheer, 1970), in children
mastering tasks involving short-term learning (Sheer,
1974), and visual problem solving in adults (DeFrance
& Sheer, 1988). Sheer (1976) also found a deficit
of 40-Hz in children with learning disabilities. For
an excellent summary of Sheer's work, see the Theory
section of Biofeedback Training of 40-Hz EEG and Behavior
researchers have confirmed that the average local electrical
activity (the field potential) in the vicinity of increased
neural activity often shows 40-Hz oscillations (Gray &
Singer, 1989; Gray, Konig, Engel, & Singer, 1989;
Gray, Engel, Konig, & Singer, 1992). Some local neurons
put out spikes, not at random moments, but "on the
beat" of other local oscillations. These 40-Hz; neurons
may fire a short burst of two or three spikes that are
in close synchrony with fellow neurons. Accordingly, the
pulses "consolidate" (Sheer, 1970) or "bind"
(Crick, 1994) the various areas of the cortex needed to
process incoming sensory and motor information. Field
potentials under certain visual conditions may be seen
to oscillate in the same phase at two areas of the cortex,
even if the electrodes are as much as 7 nim apart.
Sheer et al.'s work, Giannitrapani (1969) compared the
EEG of middle- and high-I.Q. subjects during mental
multiplication activity. A 40-Hz rhythm occurred just
prior to the subject's answering the question. Forty-Hz
pulses are thought to lead to synchronization and coordination
of neurons assigned to the processing of incoming sensory
stimulation. Put in "computerese," 40 Hz may
be the brain's "operating system" frequency.
EEG biofeedback study by B. L. Bird and associates (Bird,
Newton, Sheer, & Ford, 1978a, 1978b) evaluated three
groups of subjects: one to increase 40 Hz only, another
to bidirectionally increase and decrease 40-Hz activity,
and a control group. The increase 40-Hz group achieved
criteria in six sessions and the bidirectional group
fared less well, but still achieved training. In follow-up
studies, Ford, Bird, Newton, and Sheer (1980) showed
that one to three
later, the previously trained subjects had retained
their ability. Most still produced 40-Hz activity under
task, without having benefit of EEG biofeedback. The
EEG biofeedback research strongly suggests that 40-Hz
biofeedback training helps to improve focused arousal
and memory "consolidation," thereby potentially
relieving certain learning disabilities.
on 40-Hz Research
striking aspect of 40-Hz research is its vision and
depth. There are animal studies, human studies in both
normal people and the learning disabled (LD), biofeedback
studies showing easily trained ability to increase and
decrease 40 Hz, and long-term follow-up studies. Furthermore,
there is matching and correlated scientific theory on
every aspect. While some may argue, there appears to
be as much, if not more, science behind 40-Hz activity
as with SMR, and certainly there is more than that found
with Beta (15-18 and 16-20 Hz) EEG biofeedback
Midline Theta Activity ("Theta2")
the past several months, I have been clinically exploring
"Frontal mid Theta activity," a rhythmic frontal
Theta activity that is reported to occur during the
performance of a mental task. While the original reports
go back to the 1940s (Kennedy, Gottsdanker, Armington,
& Gray, 1948, 1949; Arellano & Schwab, 1950;
Brazier & Casby, 1952; Mundy-Castle, 1951), all
the recent research is reported by theJapanese (Inouye,
Ishihara, & Shinosaki, 1984, 1985; Inouye, Ishihara,
Shinosaki, & Tbi, 1985; Ishihara & Izumi, 1975,
1976; Ishihara & Yoshii, 1972; Mizuki, Tanaka, Osohaki,
Nishijima, & Inanaga, 1976, 1980; Mizuki, 1987;
Yamaguchi & Niwa, 1974; Yamaguchi, 1983). As "Frontal
Mid Theta Activity" seems clumsy, I refer to this
rhythm as "Theta2."
consists of trains (long runs) of rhythmic frontal activity
centering at 6.5 Hz with amplitudes reaching the 50-100
yV (microvolt) range. The maximum amplitude is just
anterior to the Fz electrode and a few millimeters to
the left of midline. The field spreads anteriorly to
an area near the Fpz electrode site and posteriorly
to the Cz, C3, and C4 electrodes.
is induced in some people by the performance of a mental
task such as mental arithmetic, tracing a maze, counting
the number of cubes piled in a three-dimensional representation,
and imaging a scene. Because Theta2 is associated with
mental tasks and its influence is seen in evoked potential
latencies, Mizuki (1987) believes that the appearance
of Theta2 closely relates to mechanisms of attention
or arousal. The incidence of Theta2, if measured during
a mental task, is 32-73% of the normal population (Yamaguchi,
is more common in extroverts with low traits of neurosis
and anxiety. For this reason, Mizuki (1987) studied
centrally acting drugs on college students to determine
if differences in anxiety levels and performance existed
between Theta2 producers and non-produceis. Diazepam,
amobarbital, methylphenidate, and a placebo were evaluated.
The State Anxiety Scale of Speilberger's State 7Yait
Anxiety Inventory (STAI) was used to measure anxiety
The mental task was arithmetic addition.
power increased and Theta power decreased after administration
of all drugs, though not with the placebo. In the Theta2
group, the placebo increased the appearance time of
Theta2, decreased anxiety scores, and increased task
performance. Diazepam increased Theta2 and decreased
anxiety, but did not influence task performance. Amobarbital
did not change the appearance of Theta2 or anxiety,
but decreased task performance slightly. Methylphenidate
failed to influence the appearance of Theta2, but did
increase anxiety slightly and markedly increased task
performance. In the nonTheta2 producers, Theta2 appeared
with drug administration even though these subjects
had not previously shown Theta2 over three days of testing.
The appearance time of Theta2 increased in the following
order: diazepam > amobarbital > placebo > methylphenidate.
Anxiety scores decreased .in the same order. Task performance
increased with methylphenidate and the placebo, but
decreased with amobarbital and diazepam. The Mizuki
study suggests that Theta2 is related to task performance
and that decreased anxiety might occur with the appearance
Hz + Theta2 = Revelation
I began trying to understand how rhythmic frontal Theta
and poorly regulated, low amplitude posterior 40-Hz
activity might be related, a fascinating thought came
to me: maybe there is a mathematical association. Dividing
39.5 by 6.5, 1 discovered that Theta2 is a sixth subharmonic
of 40-Hz activity! As I did more calculations, I found
a fascinating relationship.
(12-15 Hz) 13 Hz x 3 = 40 Hz
rhythm 9.5-10 Hz x 4 = 40 Hz
"border" 7.5-8 Hz x 5 40 Hz Theta2 at 6.5
Hz x 6 = 40 Hz
at 4 Hz x 10 40 Hz
1.3 Hz x 30 = 40 Hz
appreciate the 40-Hz mathematical correlation, it is
important to know that "40Hz" activity is
not precisely 40 Hz in frequency tracking (averaging)
peak frequency on the Lexicor NeuroSearch TM system
reveals that 40-Hz activity varies from 38.8 to 40.1,
regardless of the electrode site. The average frequency
is in the ~39.5 range. Rarely, peak frequency is precisely
40 Hz, and even more rarely an average of 40.1 Hz is
observed during a baseline (monitoring) period. When
training begins, however, and the trainee is given audio
feedback regarding 40 Hz, the peak frequency quickly
drops to below 40 Hz.
are some considerations regarding 40-Hz mathematical
of the research and clinical attention in neurofeedback
training has focused on SMR, a 12-15 Hz rhythm found
in the sensory motor region of cats sitting quietly
(Roth, Sterman, & Clemente, 1967; Howe & Sterman,
1972). While to my knowledge no one has identified an
SMR rhythm in humans, it is common to train humans with
a 12-15 Hz frequency band and call it SMR training.
(1985) extensively studied the EEG of normal children
under a large variety of mental tasks. (See also The
EEG of Mental Activities, edited by Giannitrapani &
Murri, 1988.) Using 16 2-Hz filter bands ranging from
0 to 32 Hz, measurements were made at 16 electrode sites
(the vertex electrode sites were not included). Direct
correlation was made of the EEG frequencies and the
Weschler Intelligence Scale for Children (WISC).
one would expect, the study found that EEG frequencies
associated with various mental tasks are found in a
number of frequency bands and electrode sites. Unexpected,
at least to me, was the finding that the primary EEG
power correlated with most mental tasks is in a 12-14
Hz frequency band. The power is maximal at the central
electrode sites. Of interest to some neurotherapists,
the 14-16 Hz band shows little or no association with
intelligence and mental activity. The next highest band
for most tasks is the 10-12 Hz band.
Giannitrapani EEG results suggest that so-called SMR
training may be widely effective, not because of the
existence of a sensory-motor rhythm, but because of
resonance. It may be the brain's affinity for a resonant
frequency close to 13 Hz, which is captured by the 12-15
Hz frequency band. Should this challenging thought be
true, socalled SMR training should be renamed, for example,
implication for neurotherapy is that if increased intelligence
and mental efficiency is the objective, then a frequency
band with a 13-Hz center should be used. A more desirable
frequency band than 12-15 Hz is 11.5-14.5 Hz. The Giannitrapani
study agrees with the sensory/motor electrode sites
(C3, CQ proposed by Lubar (1991),
(1993), Sterman (1972), and others. EEG activity at
the Cz electrode was not studied, so its association
is not known.
peak frequency of Alpha in most people is in the 9.5-
to 10-Hz range, a fourth subharmonic of 40 Hz. Starting
in 1938 with Berger (Gloor, 1969), a number of studies
have been published concerning the Alpha rhythm. See,
for example, Andersen and Andersson (1968, 1974).
neurons firing with 100-ms pulses (10 Hz) are common
and Alpha is the largest rhythm in the ink-written EEG,
it has been theorized that Alpha is the primary rhythm
of the brain. Therefore, almost all of the early work
around attention and consciousness is based on the Alpha
rhythm. The association of Beta and attention is a relatively
new idea (Mundy-Castle, 1951).
and Walter (1950) both agree that Alpha is the brain's
scanning mechanism. In light of logic and current neurophysiological
information, this makes sense. For example, when the
eyes are closed and the visual centers in the occipital
and parietal regions are deprived of visual stimuli,
Alpha amplitude in the posterior head regions usually
increases dramatically. Furthermore, Galin and Omstein
(1972) found Alpha magnitude decreases over the hemisphere
of the brain that is under task.
rhythm, then, appears to be only indirectly involved
in the brain's attentional mechanism. Alpha is the brain's
scanning (idling) frequency, denoting a brain "standing
by," waiting to give way to Beta should attention
be required, or to be the bridge, the gate, to Theta
and Delta for drowsiness, sleep, and certain cognitive
challenges. Alpha is therefore an important cerebral
rhythm, perhaps being mathematically a resonant piece
of the 40-Hz Grand Conductor's ensemble of frequencies.
fascinating possibility is the harmonic association
of 40-Hz activity and the Alpha/Theta Neurofeedback
training for addictions. If the 40-Hz/subharmonics theory
is correct, the objective in addictive work is to teach
the brain to open the fifth subharmonic "gate"
of 40 Hz (7-8 Hz).
may be the frequency correlate of Kenneth Blum's theory
of the Cascade Theory of Reward (1990), which leads
to the Reward Deficiency Syndrome. In Blum~s theory,
because of genetic anornalies, the neurocheniistry in
some people is satisfied with a drink (or bite) or two
while the neurochemistry of the addicted person drives
him or her into an unrelenting spiral of craving. Tying
the 40-Hz theory with Blunfs theory, it appears that
those with genetic anomalies (addictive tendencies)
can be "locked out" of certain EEG frequencies,
and thus certain neurochen-listry (or vice versa). As
a result, those with addictive craving are not able
to feel rewarded (satisfied) while non-addictive people
there are exceptions in EEG patterning, the alcoholic's
EEG while sober often demonstrates a low voltage Beta
pattern mixed with low amplitude Theta and Delta activity
It is the type of low-voltage fast, "non-Alpha"
EEG that is commonly associated with anxiety. If the
alcoholic takes a relatively small amount of alcohol,
he or she may quickly slip into a relaxed physiologic
state and exhibit a relatively high amplitude, well-modulated
Alpha rhythm. With that first drink, however, the brain
of the alcoholic demands more alcohol. Instead of mellowing
into an Alpha/Theta state as "normal" people
do, additional amounts of alcohol cause a rapid descent
into higher and higher amplitude Theta and Delta activity.
The Alpha/Theta border of 78 Hz is seemingly "passed
may be that the addicted person can open 40-Hz's fourth
Harmonic gate (Alpha) with the alcohol or drugs. But,
whether it is an anomalous gene, aberrant EEG frequencies,
inappropriate neurochemistry a neurochemical "lock
out," or some other reason, the alcoholic is not
able to open the fifth subharmonic 7-8 Hz gate. Instead
of entering the Alpha/Theta state, the person sinks
into the high-amplitude slow waves of profoundly lowered
Neurofeedback results in some 80% of those addicts properly
trained becoming non-craving, having a mellow personality
and significantly adjusted neurochemistry (Peninston
& Kulkosky, 1990). Alpha/Theta training may be a
process by which the previously closed fifth subharmonic
gate (40-Hz divided by 5) can be opened and certain
critical neurochemistry accessed.
Beta to fit the 40-Hz/Subharmonics, theory, the frequency
would have to be = 19.6 (= 39.5 divided by 2). Peak
frequency evaluations of the 18-22 Hz Beta band in a
small number of subjects show that = 19.6 Hz
is close to the band's frequency peak.
the 40-Hz/subharmonics theory and early results are
correct, Beta should be trained, not at the 15-18 Hz
frequency band as suggested by Othmer (1991) or the
16-20 Hz range as proposed by Lubar (1991), but at 18-22
Hz. Lubar's 16-20 Hz band seems close to the theoretical
Beta frequency band, but his 16-20 Hz band is marginal.
The ~19.5 frequency center is to the far limits of the
filter, probably restricting full access to the desired
to Inouye, Ishihara, Shinosaki, and Toi (1988), Theta2
has a prominent spectral peak at 6.5 Hz with smaller
peaks at 3.2 and 13 Hz. The figure shown in their article
(Figure 3), however, shows the lower spectral peak to
be approximately 2 Hz (a twentieth subharmonic of 40
Hz) instead of 3.2 Hz as stated in the text. The 13-Hz
finding is a second harmonic of Theta2, a third subharmonic
of 40 Hz, and the primary frequency that Giannitrapani
(1969) found with most mental functioning.
at 4 Hz
to Cavanagh (1972), Theta at 4 Hz corresponds to a full
memory search. Theta, then, like Alpha, is a scanning
frequency. Cavanagh began by compiling a number of studies
dealing with different classes of stimuli (digits, colors,
letters, words, geometrical shapes, random forms, and
nonsense symbols). Each class of stimuli was found to
have a characteristic reaction time. However, he found
a constant of 243.2 ms when multiplying the reaction
time for a single item by the maximum number of items
in a given class. This indicated to Cavanagh that each
item class was scanned at a different speed, but that
scanning of the full memory is always executed at a
speed of 4 Hz.
(1985) states that according to the Cavanagh (1972)
research, the brain has different scanning frequencies
available for items of different degrees of complexity.
I assume, based on the comments, that these scanning
frequencies are all in the Theta range. The Giannitrapani
study also shows a positive relationship between the
level of performance for certain verbal subtests (WISC
Information, Comprehension, Vocabulary, Block Design,
and Verbal IQ) and 3-7 Hz Theta activity.
conclusion one could make from these data are that the
brain uses Theta band frequencies for important scanning
and memory functions. Therefore, inhibiting Theta during
neurofeedback training could conceivably be detrimental
to memory storage and cognition.
recent months, I have monitored the Peak Frequency of
0-32 Hz activity on every neurofeedback session. I have
found that peak frequency at a variety of electrode
sites may be as low as .9 and as high as 4.2 Hz. The
average peak frequency in the vast majority of patients
is, however, in the 1.21.4 range, averages that are
in mathematical alignment with the 40-Hz theory. Delta
also has mental/EEG associations: WISC Information (right
fronto-central), Comprehension (left central), Vocabulary
(right temporal), Digit Span (right occipital), Verbal
on Decrease Theta and Decrease Delta Training
the past two years or so, I have been doing Decrease
Delta training on children and adults with attention
problems. I have found that if the training objective
is to increase SMR or Beta, teaching Delta to downtrend
at Cz or Pz will generally be more effective than attempting
to reward the increase of SMR or Beta.
am discussing Decrease Delta and Theta training at this
time and in the context of this theoretical paper due
to my personal communication with others regarding this
training. It seems important to clarify my training
protocol, in case of second-hand misinformation, especially
in light of the information presented.
I first started doing Decrease training, I began with
Decrease Theta at 48 Hz. Results were admittedly quite
good, at least in regard to increasing SMR and Beta.
When I read about Theta2, however, I realized that there
could possibly be some interference with cognitive processing
by decreasing Theta above 5.5 Hz- As a result, I changed
my primary Theta band to 3-6 Hz, calling it Thetal,
and created a new secondary frequency band of 5.5-8
Hz, which became Theta2.
time, I decided that any Decrease Theta training might
be counterproductive to certain cognitive tasks,memory
in particular (Cavanagh, 1972). The Delta frequency
band, which I had changed to 0-3 Hz, then became my
preferred band for the downtrending of slow wave activity.
is not known how many children in the Giannitrapani
(1985) study would be diagnosed with attention deficit
disorder. Considering the sampling (general population),
however, some probably were. In any case, Giannitrapani
found that both Theta and Delta frequency bands have
associations with mental processing. For example,Delta
is seen in the EEG during the administration of the
WISC comprehension test.
training objective then is not to decrease Delta or
Theta per se. The objective is to teach Delta to
downtrend under a performance challenge such as
the Game Boy" strategy game Tetris". Once
the "decrease under task" goal is achieved,
Decrease training is considered complete. The next training
as specified in my clinical strategy protocol is then
interesting thing about teaching Delta to downtrend
under task is that the resting Delta magnitude may actually
increase as a result of the training. Higher amplitude
Delta (implying more Delta is available) that decreases
under task as SMR or Beta increases suggest that mental
and attentional flexibility is improved. It appears
that by doing Decrease training, Delta and certain fast
frequencies are "unstuck." This flexibility
is in alignment with the Giannitrapani study (1985)
which shows that specific frequencies need to be available
for certain mental tasks, Delta included. In the case
of increased magnitude or percent power of Delta or
Theta activity on a reference database, the clinical
neurofeedback objective, of course, is to reduce the
abnormal slow waves to normal magnitude levels.
Hz/40 Hz Notes
interesting mathematical correlation with 40 Hz is the
EEG during meditation. Banquet (1973) found 20- and
40-Hz EEG changes in advanced Transcendental Meditators
during the third stage of meditation (considered to
be deep meditation or "transcendence"). The
EEG was characterized by a dominant Beta rhythm at 20
the ink written record, Beta periods appeared at both
20 and 40 Hz. The amplitude of the background activity
reached a surprisingly high voltage of 30-60 yV. Beta
was mainly in the anterior head regions, but was sometimes
present diffusely. In the compressed spectral arrays
(CSA), the 20-Hz Beta power peaks seem to lie on an
unvarying straight line with high amplitude, suggesting
unusually regular frequency and amplitude. Forty-Hz
activity, in comparison, is of significantly lower amplitude
and of less steady regularity. The CSA shown in Banquet's
article (1973) fits Cricles description of 40 Hz (1994),
which he says is "more like a freehand drawing
of a wave than a very regular mathematical wave of constant
frequency." The spectral array also demonstrated
a marked amplitude increase in the Delta range. Unfortunately,
the peak frequency of the slow waves is not stated in
and Gastaut (1955), recording from seven trained Yogis,
reported high amplitude levels of 40-Hz activity during
the Samadi state, which is the final, most intense concentration
state in this form of meditation. Pollini and Peper
(1976) reported Beta activity at 18-20 Hz in subjects
In summary, when the body is profoundly relaxed and
the mind is in a state of high focus and concentration,
20- and 40-Hz brain activity can be seen in the raw
and quantitative EEG of some subjects. It is possible
that 18-22 Hz Beta and possibly 40-Hz neurofeedback
training may help create a "relaxed body/focused
mind" state of consciousness.
versus 12-15 Hz,
15-18 and 16-20 Hz Training
is not yet known whether 40 Hz, a subharmonic of 40
1U, or harmonically unrelated other frequencies are
the most efficient training for the remediation of cerebral
dysfunction (learning disabilities) and attentional
problems (Attention Deficit Disorder). As pointed out
by Sheer et al. (1966), memory consolidation and learning
impairments have not been adequately addressed in EEG
biofeedback. Most of the research has been directed
toward attempting to quiet the child's motor activity,
that is, hyperactivity, rather than dealing with the
learning problems and attentional flexibility. Subsequently,
Increase SMR/Decrease Theta has historically been the
most popular neurofeedback training. As 40 Hz specifically
addresses the area of learning disabilities and memory
consolidation ("focused arousal"), the training
of 40 Hz may have a place in neurotherapy.
strong consideration in any discussion of 40-Hz biofeedback
training is the difficulty of training such a fast frequency.
Significant electromyographic (EMG) contamination can
naturally infringe and contaminate the training band.
Sheer (1976), with further sophistication by Bird et
al. (1978a), worked to overcome the EMG contamination
problem by devising biofeedback equipment with a special
"comparator' circuit. If EMG (at 72-78 Hz) occurs
concurrently with 40-Hz activity (35-45 Hz), the "comparator"
circuit discontinues EEG biofeedback until the EMG subsides.
my knowledge, "comparator" circuits are not
available on any commercially available EEG biofeedback
equipment. The Lexicor NeuroSearch" (and probably
others) allows the silencing of the audio feedback should
the magnitude of tbe frequency bands selected (EMG included)
exceed the threshold set by the therapist. This filtering
arrangement, while helpful, is probably not adequate
to allow training of 40 Hz in tense and restless
with 40-Hz Biofeedback Training
is thought to be either "off" or "on."
For this reason, the neurofeedback objective may be
to increase the amount of time that 40 Hz is on, rather
than to attempt to increase its amplitude. The audio
reward tone is therefore adjusted for a "flat"
tone response rather than a "sliding" tone
that becomes higher-pitched with increasing amplitude.
seems important to train 40 Hz in brain areas that are
associated with known sensory and motorprocessing, that
is, the central and posteriorly placed electrodes (C3,
C4, Cz, T5, T6, P3, P4, Pz, 01, and 02). It is important
to avoid the midtemporal electrode sites because of
the temporalis muscle.
Lexicor NeuroSearch"' requires a sampling rate
of 256 to record 40-Hz activity
EMG file in Bands was changed to 48-52 Hz. If EMG is
excessive, it is inhibited at the 20% level. A marked
increase in EMG with a concomitant increase in 40 Hz
suggests that the 40-Hz frequency band is being contaminated
with EMG artifact. Forty-Hz magnitude increases should
bediscounted in these cases and in intersession training
doing 40-Hz training, the client/patient should be continuously
engaged in a cognitive task such as TetriS T1. Non-verbal
tasks and tasks with low potential for EMG contamination
Clinical Notes on Theta2 Training
Theta2 (Frontal mid Theta in the literature) is by definition
rhythmical may present a technical problem. 'Ib my knowledge,
no EEG biofeedback equipment has a "rhythmicity
filter," which would allow the recording of rhythmic
activity to the exclusion of non-rhythmic activity In
spite of this, I decided to trust the innate wisdom
of the brain and attempt the training of Theta2.
of children and adult trainees alike report improved
behavior and performance after Theta2 training. However,
neither have been measured with standard instruments.
To complicate matters further, I have not done Theta2
training exclusively on any patient; it has always been
done in combination with Increase SMR (12-15 Hz) or
Beta (15-18 Hz), Decrease Delta and/or Theta, and a
variety of Coherence, Phase and Symmetry training.
said, a notable positive experience that seems directly
attributable to Theta2 training is that of a 10-year
old boy, heavy into knives under the mattress and the
drawing of violent war scenes of robot warriors. This
boy quickly mellowed with
training, much as is reported with Alpha/Theta training.
All signs of violent behavior stopped. The robot cartoons
continued to be drawn, but were essentially noncombative.
My clinical experience with this boy is in alignment
with Mizuki's (1987) drug studies showing less anxiety
and neurotic behavior in those with Theta2.
clinical experience with Theta2 thus far suggests the
present training objective with Theta2 training is to
make Thetal (3-5.5 Hz) and Theta2 (5.5-8-0) autonomous.
That is, while the trainee is under cognitive challenge,
Thetal should independently decrease over the session
as Theta2 increases. When Theta2 stabilizes (remains
the same over a session or two) as Thetal decreases,
I consider Theta2 training to be complete.
training session time may be shorter than my usual training
session time of 20 to 25 minutes. At the first clear
indication of Theta2 downtrending (two quick decreases
in the Theta2 magnitude averages while the trainee is
under continuous cognitive challenge), stop the session.
If the session is continued, Theta2 averages tend to
downtrend and advances quickly decay. The Theta2 downturn
can occur as early as 10 minutes into the session so
the clinician should constantly monitor the magnitude
a few sessions are indicated for Theta2 training. Sessions
should only continue until Theta2 increases and Thetal
downtrends while the trainee is doing a cognitive task.
If sessions are continued after this point, the trainee
seems to rapidly lose Theta2 magnitude gains. Only around
five or seven sessions have been required in those trained
doing Theta2 training, the client/patient should be
continuously engaged in a cognitive task such as Tetris".
Non-verbal tasks and tasks with low potential for EMG
contamination are preferred.
training protocol is based on my current electrophysiological
perceptions. Much research and experience are needed
to determine the proper protocol for Theta2. What is
even more important is that it must be clinically determined
whether increasing the magnitude or percentage time
of Theta2 will yield such anticipated benefits as increased
mental performance, improvement in anxiety states, and
improved socialization in those with antisocial or unsocial
theories regarding 40 Hz are proposed:
known clinical EEG frequencies, especially those shown
to remediate attention problems and quiet hyperactivity
(12-15 Hz), alcohol and drug addictions (Alpha/Theta
at 7.5-8 Hz), and mental processing (Theta2 at 6.5 Hz
and Theta at 4 Hz) mathematically relate to 40 Hz, an
EEG frequency band centering at = 39.5 Hz.
is proposed that those with attention problems, addictions,
and mental processing problems (such as learning disabilities)
may have restricted, limited, or no access to critical
areas of cognitive and neurological functioning. Neurofeedback
aids in the opening of certain critical, frequency-related
"gates" in cerebral function to which the
trainee previously had restricted, limited, or no access.
activity represents a chord-a computation- composed
of several resident key brain frequencies. If these
resonant frequencies are fully and dynamically present,
maximum cerebral potential (volitional accessibility
to specific neuronal functions, multiple states and
levels of consciousness, and attentional flexibility)
deficiency, or excess in one or more key frequencies
leads to discordance of 40-Hz activity, which in turn
leads to hampered ability (a deficit) of some specific
operation in cerebral functioning. Neurofeedback aids
in the restoration of specific key resonant frequencies,
thereby restoring full clarity to the 40 Hz.
readers with an interest or background in physics, it
will be clear that 40 Hz itself may be a subharmonic
of a still higher cerebral frequency EEG frequencies
over 40 Hz have been reported and I have recorded what
appears to be true EEG activity at frequencies up to
is anticipated that the 40Hz/Subharmonic theory will
be met with both intrigue and skepticism. The contribution
is presented to stimulate dialogue in anticipation that
in doing so, the process of what we call neurofeedback
will be better understood. Comments and questions are
recommendations or claims are made regarding the efficiency,
efficacy, or safety of a specific frequency or type
of neurofeedback (EEG biofeedback) training. The reader,
whether researcher or clinician, is solely responsible
for the outcome of any training done on the basis of
the information and theory presented.
articles on 40 Hz *
summary article on 40-Hz **
Key articles on Theta2 ***
Key summary article on Theta2 tt
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