A Monthly Summary of News and Events
Vol. 4 No. 10 - October 2001
This newsletter is sponsored by EEG Spectrum International Intl, Inc.,
a leader in providing clinical service and training professionals.
Past issues are available at www.eegspectrum.com/newsletter/
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The opinions related in this newsletter reflect those of the author only.
Copyright (C) 2001 by EEG Spectrum International Intl, Inc. All rights reserved.
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I propose a Functional Model of Mental Health (version 1.1) as an attempt to interject some paradigm into a largely observational science, neurotherapy. Premise #1 is this: Healthy neural systems respond appropriately to stimulation. Stimulation can be either internal (processing demands) or external (sensations) etc. By healthy we mean the obvious, but you can choose a synonym if you like from the biology or neurology such as adaptive or functional.
Now to operationalize this premise, to be able to measure it, we need another premise:
Well, Premise #2 is: No neural tissue is an island.
To process information, neurons must necessarily recruit other neurons into their fantasy. (Isn't all processing at this level a simulation and thus phantasmic?) The ability of tissue to be recruited and unrecruited (freed from recruitment) reflects its stabililty and functionality. Neuroscientists and psychologists witness recruitments on large scales as transitions from moderate to extreme states of functional differentiation and functional conformity. How quickly and easily the two polar extremes are attainable by a system may be the best objective measure of functional health.
By functional differentiation I mean observing dissimilar activity or responsivity in proximal neuronal regions, be they individual cells, neural groups, modules, recording electrodes, or entire hemispheres, whatever your scale of recording. Functional conformity is the opposite: neighboring regions show little or no differences in activity or responsivity. The degree of conformity or differentiation can be quantified with numerous techniques, but I shall briefly examine two QEEG approaches: comodulation and event-related desynchronization.
When an individual's resting or idling state (called set point in the model) hovers around functional conformity, something is probably wrong with this person's brain and ability to function. The set point may tend toward extreme functional conformity (e.g., abnormally high amplitudes during eyes closed baselines, hypercomodulation of frontal sites) in cases of neurological and psychological disorders. If this model holds up, the goal of neurotherapy is to improve the idling condition, to release it from the constraints of functional conformity, and to condition the system so it can freely move between differentiation and conformity and back again.
Functional differentiation
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| Ease between state transitions
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Functional conformity
In comodulation, a single frequency band is evaluated, normally the dominant frequency, and how the spectral magnitude varies for this single band across time is compared between pairs of recording sites. High positive correlations between sites (across time) indicate functional conformity whereas low or zero correlations indicate extreme functional differentiation: the neural groups are acting independently of each other
The comodulation measure often reveals that a depressed person exhibits too much frontal functional conformity, specifically between the left medial frontal site (F3) and its neighbors (Fp1, F7, Fz). F3 follows the activation patterns of its nearby sites, it fails to functionally differentiate, and therefore it cannot be performing all of its normal functions (its functions presumably differ from its neighbors' most of the time and notably include mood elevation). (Perhaps an unstated corollary of premise 2 is violated here: no neural tissue is an island, but also no neural tissue is a continent either, at least not in a healthy individual).
Normative databases evaluate an individual's set point. (I should qualify the previous sentence with "as currently constructed.") Although the eyes closed condition alone tells us how functionally conforming one's resting state is, it fails to depict how readily an individual can leave or transform the state. Including an eyes open condition and challenge tasks allow evaluations of the extent that functional differentiation can occur when processing demands increase.
To quantify conformity and differentiation, and the ease of transition between the two, we now turn to the event-related desynchronization (ERD) technique. In ERD analysis, which is much like EP analysis but within the frequency domain, a subject is engaged in a short, repetitive, well-controlled task; EEG is recorded for these short intervals (trials) and multiple trials are averaged together to eliminate random processes and noise. For instance, for a memory task, a target is presented every 2 or 3 seconds which the subject must respond to. The EEG data recorded for each 3-second trial is submitted to periodic analysis (FFT), using overlapping windows, so that spectral characteristics can be investigated as they change moment to moment across the trial.
In such trials, one sees four general components: a (1) latency and (2) amplitude of event-related desynchronization (ERD), which indicates stimulus processing and preparing and performing a response, and a (3) latency and (4) amplitude of the post-response synchronization (PRS), which occurs after cognitive effort is complete.
The extent of the ERD demonstrates how well the subject can recruit cell groups into performing the cognitive task: how many and how quickly neural groups can be organized away from the synchronized idling state. Thus an ERD analysis provides an index of relative functional differentiation. But even more important to functional capability and health may be the PRS component. The PRS indicates how quickly and well a system can organize activated cells back into a synchronized holding state. The latency and relative amplitude shows what I together with the ERD I call the ease of release dynamic: how well a brain adapts to processing demands, followed by how easily it releases from activation and returns to a background state.
So version 1.1 is released, awaiting improvements, bug reports, and likely to be made obsolete by some Microsoft-like hackware.
News & Reviews
NEW BOOKS
The Forensic Evaluation of Traumatic Brain Injury: A Handbook for Clinicians and Attorneys
by Gregory J. Murrey
Stress and Health: Research and Clinical Applications
Functional Imaging in the Epilepsies
Essential Guide to Depression
Autism Spectrum Disorders: A Transactional Developmental Perspective
Dual Diagnosis Recovery Sourcebook: Addiction with an Emotional Disorder
Stroke: A Practical Guide to Management
Alpha and beta band power changes in normal and dyslexic children.
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A strong beta-1b desynchronization above Broca's area (FC5) and the angular gyrus (CP5, P3), appears to reflect the graphemicphonetic encoding of words.
Which Patients with Major Depression Benefit from Prefrontal Repetitive Magnetic Stimulation
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Negative predictors of response to prefrontal rTMS are advanced age, cognitive impairment in frontal tasks, and non-response to electroconvulsive therapy, among other factors.
Does EEG predict response to valproate versus lithium in patients with mania?
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The presence of nonepileptiform EEG abnormalities predicts response to valproate and non-response to lithium to a moderate degree.
Excess beta activity in children with ADHD: an atypical electrophysiological group.
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Excess-beta group (primarily in frontal lobe) were more prone to temper tantrums and to be moody, but otherwise was similar to other ADHD children.
Neuropsychology of multiple sclerosis: contributions of neuroimaging research.
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A review of individual differences in the neuropsychology of MS, with emphasis on neuroimaging studies.
Localization of MDMA-induced brain activity in healthy volunteers using LORETA
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MDMA produces widespread decrease of slow and medium frequency activity and an increase of fast frequency activity in anterior temporal and posterior orbital cortex as analyzed using LORETA.
Psychopathology as a predictor of adolescent drug use trajectories.
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Drug use prevention programs should target youths with early symptoms of psychopathology.
Brain metabolic changes associated with symptom factor improvement in major depressive disorder.
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Improvement in cognitive disturbance in depression is associated with increasing dorsolateral prefrontal cortex metabolism.
Predicting Relapse to Alcohol and Drug Abuse via Quantitative EEG
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Enhanced amount of high frequency (19.5-39.8 Hz) beta activity was observed in patients who later relapsed compared to those who maintained abstinence and controls.
Frontal lobe changes in alcoholism: a review of the literature.
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A review of literature supports the concept of frontal lobe pathology in alcoholism.
Upcoming Courses
Prerequisites:
All Adv. classes require successful completion of the 4 Day Comprehensive Beta/SMR.
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Conferences for Neurofeedback Clinicians & Researchers | ||
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| CONFERENCE | LOCATION | DATES |
| SNR - http://www.snr-jnt.org./NewsPlus/2001/2001-sched.htm | Monterey, CA | Oct 27-30 |
Large-N Project II
In 1992, while working in Barry Sterman's laboratory at UCLA, I began a personal project which I titled the Large-N study. I devoted a single manilla folder to the project at first -- not a very auspicious beginning. However this folder contained promise; it contained subject information, recording procedures, and copies of completed questionnaires from all the data files recorded in our lab. In 1994 I sorted through the now-larger and growing data set. Many of the recordings were short in duration or included atypical tasks, but records from 130 subjects were homogeneous enough to be compiled and compared.
This data set allowed Barry and I to investigate components of the EEG not readily identified in smaller batches of 20 or so. In September 1994 the first fruits of this pet project were presented at the 7th Annual Summer Sleep Workshop Multi-Site Training Program for Basic Sleep Research, at Lake Arrowhead, California. We presented quantitative topographic EEG during baseline conditions to demonstrate the impact of circadian and ultradian rhythms on the EEG. I joined EEG Spectrum, Inc. the following year and eventually posted our presentation on their website to support my "EEG and the Sun" newsletter articles. (The poster is apparently not available at the new site, but it's mirror resides at Periodicity of Standardized EEG Spectral Measures across the Waking Day - David A. Kaiser and M.B. Sterman )
I would now like to propose a Large-N II project, one for the entire field of neurotherapy. Such a project centers around a single website, currently unnamed, preferably one with anonymous FTP access. It will become a repository for EEG files that anyone can upload and download freely. Think of an "open-source" data set analogous to the Linux operating system. I use the term "data set" instead of "database" because I can foresee people organizing these data files into value-added databases and these probably need to be proprietary to compensate these efforts (else who could afford to put in the work). Some method of compensating file contributors such as free or reduced cost copies of the final database might be the site's general contractual agreement.
One benefit of this project will be the evolution of a standardized data acquisition methodology. As people witness data collection techniques on a large scale -- the how, what, and why of QEEG from numerous clinicians and researchers -- we might settle on a list of standards for recording EEG data for the field.
Another benefit of such a project is circulation. Keep the data in circulation. Say you collect EEG from a dozen or so autistics and years later move on to greener pastures and an MBA degree. There are many who could benefit from the 1's and 0's slowly decaying on your now-incompatible hard drives and backup tapes. Such an online archive will also be extremely helpful in teaching EEG methods.
I make this personal proposal on November 1, 2001 but realize that a team of people are necessary to pull this off, so who's game?
And you should know the basic facts before claiming anything about another person's work. Don't you think?