Eyes Closed recordings from 135 subjects.
A Monthly Summary of News and Events
Vol. 3 No. 8 - August 2000
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EEG and the Sun
(Two years later)
August is a month associated with the Sun, a time for escaping the heat and taking vacations from work. Not only does the nearby star dictate our whereabouts this time of year, be it the beach or an air-conditioned hotel room, it dominates most processes within six trillion miles or so. And human EEG is no exception.
Because humans evolved on a spinning planet, it shouldn't be surprising that most of our biological rhythms are synchronized with the rotation period of terra firma. However some continue to question whether EEG exhibits circadian effects. Does EEG activity wax and wane with the positions of the Sun? And if so, what relevance may it hold for neurofeedback and QEEG evaluations?
The first paper to find circadian effects in the EEG was published during the Nixon administration (Scheich, 1969). Many more was published in the mid-80s.
Six years ago I presented ample evidence of the Sun's influence on a wide range of frequency activity (Kaiser and Sterman, 1994). More than 130 subjects, recorded at various times across the day, showed prominent ultradian and semi-circadian effects in multiple frequency bands. For example, alpha activity at recording site Pz shows the following:
Over the years a few scientists have questioned my data and suspected that any circadian rhythm apparent in the EEG was probably due to drowsiness or hunger or lunch. One scientist suggested that if the drowsy epochs were clipped out of my data set, the EEG would remain relatively flat throughout the entire day. Essentially, this person, and others before and after him, argued that EEG is about the only physiological, biochemical, or endocrinological process unaffected by circadian rhythms.
What biological processes are influenced by a 24 hour priod of light and darkness? In short, nearly all of them. Thousands of papers describe circadian rhythms -- in body temperature, heart rate, motor activity-- you name it; far too many to relate here. A recent paper on ultradian cycles in event-related potentials (Polich, 1997) found evidence of ultradian rhythms in the background EEG and in the ERP signals themselves. So why do a few stubburn neuroscientists and psychologists deny the existence or importance of circadian or ultradian rhythms in gross neuroelectric activity? Perhaps the clearer argument would be that such cycles, if they exist, are not relevant to neurofeedback assessment or training. Perhaps... But the following (true) example points to how time of day can be critical in neurofeedback training:
A woman with epilepsy undergoing neurofeedback kept track of the amplitudes of her reward band from session to session. She had two clinicians who supervised her training: her regular clinician, and a less-experienced clinician who substituted for her regular clinician whenever he was out of town (which was often). After a few weeks of training, some by her regular clinician, others by the relative novice, the client noticed something unusual about her training sessions. She performed much better when her regular clinician was unavailable. With her regular clinician, she averaged around 5 microvolts each session in her reward frequency band, but when the substitute trainer was supervising the session, it was not unusual to average 7 or 8 microvolts. A 50% improvement over her regular clinician! Well, it didn't take long before both she was convinced that her regular clinician's approach was inferior to the sub's. She was convinced she had uncovered what in psychology is called an experimenter effect: the person performing an experiment can alter the results. Was an experimenter effect responsible for her performance-- yes and no. It was not the sub's clinical approach or his rapport with her or some other aspect of his person that motivated her exceptional performance each session. It was his dislike of rush hour traffic. You see, the woman normally scheduled her sessions for 5 pm, but the sub hated the drive at this hour so he always scheduled their sessions later, usually 7 pm. The two-hour difference in the time of day was responsible for her higher amplitudes, not any clinical approach.
There's nothing new under the Sun, so the saying goes. The woman and her new trainer had simply rediscovered what was already known. In November 1983, Gertz and Lavie published a paper in the journal Psychophysiology which should have focused attention on the possible confounding influence of circadian rhythms on EEG biofeedback. The paper was for titled: "Biological rhythms in arousal indices: A potential confounding effect in EEG biofeedback" Gertz and Lavie recorded EEG from 11 subjects for about 8 hours each. During this time, arousal was evaluated (albeit subjectively) and between EEG recordings subjects underwent a form of EEG biofeedback. They observed significant ultradian rhythmicity in the EEG (at about 200 min/cycle, the Basic Rest Activity cycle). The rhythmicity was also apparent in the arousal measure. They also reported a more prominent circadian rhythm during eyes closed than during eyes open conditions. They correctly concluded that because "the observed ultradian and circadian EEG rhythmicities could be spuriously interpreted as learning curves under a biofeedback paradigm, it is argued that future designs should incorporate continuous baseline controls." Wise advice which has been entirely ignored.
In 1995 we reported that absolute magnitudes in almost every frequency band were similarly modulated across the day. The Sun had long ago set a timer or two inside the brain and we rediscovered this basic fact. For our efforts, our data and conclusions immediately came under suspicion. Those who should have recognized the obvious role of the Sun in neurophysiology and neurofeedback, who encountered it each and every day, were the most obstinate. Perhaps because they had not discovered the obvious fact on their own.
In the last year, three papers have been published on the confounding influence of circadian and ultradian rhythms in human EEG. Cummings et al (2000) recorded eyes closed and eyes open conditions across a 24 hour period in 18 subjects. Not particularly interested in ultradian rhythms, they recorded data every two hours. They reported notable circadian effects in theta, lower alpha, and lower beta (and looking over their data, potential though less prominent effects can be seen in all bands they analyzed).
They concluded that the circadian effect accounted for 20-30% change in group means; and that any clinical effect that did not control for time of day must be greater than 20% to be taken seriously. They argue that such a large effect requires design changes in pharmaceutical trials -- as it should in any form of QEEG evaluation.
Aeschbach et al (1999) reported two distinct circadian rhythms and possible mechanisms. Theta activity peaked one hour after the onset of melatonin secretion and high alpha activity exhibited a minimum close to the body temperature minimum. They conclude that differnces in the rhythm timing indicated different functional significance of these EEG activities. They did not analyze for ultradian effects; however there appears to be indications of ultradian rhythms in the data they presented.
Chapotot et al. (200) examined ultradian effects in the QEEG in 12 subjects recorded across the day. They reported ultradian rhythms of 180-240 minutes in almost all frequency bands from 1 to 45 Hz.
All in all, circadian and ultradian rhythms may be less a problem in neurofeedback training than in QEEG evaluation. Most people who see a clinician regularly do so at about the same time of day each time, due to work or school schedules. Time of day is more likely to vary between widely-spaced recording sessions (assessments) than between shortly-spaced sessions (training). And most clinicians nowadays work with reinforcement schedules (e.g., 70% above threshold, 80% above threshold, etc.) more than amplitude values. Assessments, which are usually widely-spaced sessions, are more vulnerable to time of day effects. The best solution adopted by many offices is to test people only at one time during the day, typically around 10:00 am in the morning. But what happens when the client is running late? When they appear at 11:30 am, are they rescheduled for the next day or are they re-tested anyway then and there? In other words, do you let the Sun into your data or not?
DK
Chapotot F, Jouny C, Muzet A, Buguet A, Brandenberger G. (2000). High frequency waking EEG: reflection of a slow ultradian rhythm in daytime arousal. Neuroreport, 11, 2223-7.
Aeschbach D, Matthews JR, Postolache TT, Jackson MA, Giesen HA, Wehr TA. (1999). Two circadian rhythms in the human electroencephalogram during wakefulness. American Journal of Physiology, 277, R1771-9.
Cummings L, Dane A, Rhodes J, Lynch P, Hughes AM. (2000). Diurnal variation in the quantitative EEG in healthy adult volunteers. British Journal of Clinical Pharmacology, 50, 21-26.
Synopsis of Neuropsychiatry
The Scientific American Book of the Brain
Madness on the Couch: Blaming the Victim in the Heyday of Psychoanalysis
Brain Mystery Light and Dark: The Rhythm and Harmony of Consciousness
Language and the Brain
The Brain: Degeneration, Damage and Disorder
Neuropsychiatry and Mental Health Services
Case Studies in Neuropsychological Rehabilitation
Diurnal variation in the quantitative EEG in healthy adult volunteers. : QEEG recordings (eyes open and closed) taken at 2-hr intervals throughout the day in 18 subjects revealed circadian rhythms in theta, low alpha, and low beta wavebands. Time of day confounds QEEG analysis and must be controlled for.
Review of neuroimaging studies of child and adolescent psychiatric disorders from the past 10 years. : A review of neuroimaging studies of childhood-onset psychiatric disorders, notably schizophrenia, autistic disorder, ADHD, and anorexia nervosa, found that although structural abnormalities were consistently reported, the nature of these abnormalities differed across studies.
Neurobiology of addiction. Toward the development of new therapies. : Drug addiction is a chronic functional dysregulation characterized by neurobiological changes that result in positive reinforcing effects of drugs and a vulnerability to relapse and re-entry into the addiction cycle.
Abnormal neuropsychological findings are not necessarily a sign of cerebral impairment : Abnormal test findings in the absence of neurologic impairment may not be a reliable sign of cerebral impairment.
Neuropsychological functioning in nonreferred siblings of children with ADHD : Neuropsychological functioning of nonreferred siblings of children with ADHD is often impaired. Siblings with ADHD were impaired on the Stroop test and on verbal learning and memory.
Family environment in ADHD, oppositional defiant and conduct disorders. : Conduct disorder and oppositional defiant disorder, but not ADHD, are associated with poorer family environments. Improving the quality of family life, particularly in early childhood, may prevent the development of conduct problems.
Ecological Validity of Neuropsychological Assessment in Childhood Traumatic Brain Injury. : Standardized neuropsychological tests do not predict everyday functioning of childhood TBI patients very well.
Brain mapping of bilateral interactions in ADHD and control boys. : Brain mapping indicates multilevel deficits in ADHD boys affecting visuo-attentional and pre-motor processes.
Neuropsychological Deficits in Psychotic Versus Nonpsychotic Major Depression and No Mental Illness. : As expected, patients with psychotic major depression are more impairmed than patients with nonpsychotic major depression. Psychotic major depression is associated with impairment in frontal and mediotemporal cortical function.
Lesion pattern in patients with multiple sclerosis and depression. : Depressed multiple sclerosis patients have larger temporal lesion load than non-depressed MS patients, especially on the right side.
Task switching and attention deficit hyperactivity disorder. : Executive control processes required for the coordination of multiple tasks were evaluated using switching tasks. Unmedicated ADHD children showed substantially larger switch costs than controls.
| EEG Spectrum International Intl is offering a series of workshops addressing topics of interest to professionals working in the field of neurofeedback. Class size is limited to 25 to allow for informal interaction. | |
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Psychopharmacology, Nutrition, and Neurofeedback
Bruce Goderez, M.D. Boston, MA Sep 23-24, 2000 Beta/SMR Skills Enhancement & Case Review Sue Othmer, BCIA Encino CA Oct 7-8, 2000 | |
For information, call EEG Spectrum International Intl at 818-789-3456 x 810 or email training@eegspectrum.com
PREREQUISITES FOR EITHER PRACTICUM:
Conferences for Neurofeedback Clinicians & Researchers | ||
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| CONFERENCE | LOCATION | DATES |
| SNR | Minneapolis, MN | Sep 20 - 24 |
Reactive Attachment Disorder (RAD)
a letter by Sebern Fisher
A reply to a an adoptive father's request for information on RAD and neurofeedback.
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Sebern |