NeuroRegulation

Infra-slow Fluctuation (ISF) electroencephalogram (EEG) biofeedback is a recent development in neurofeedback training. This form of training is focused on the lowest energy the brain produces (< 0.1 Hz). The intervention is performed with a Direct Current (DC) coupled neurofeedback amplifier. It is distinct from Slow Cortical Potential (SCP) training and Infra-Low Frequency (ILF) training. It shares a similar optimization process with ILF that focuses on emergent state shifts within sessions. These state shifts require frequency adjustments that optimize client response to the training in real time. Due to the technical difficulties inherent in recording these frequencies, EEG investigators largely neglected this low energy until recently. As DC amplifiers improved, the slow frequencies became a signal of increasing interest to researchers. Research has demonstrated an important role for the infra-slow oscillations in clinical work. Positive clinical case outcomes suggest that a larger controlled study is warranted. The technical, clinical, and equipment requirements of the intervention make this form of neurofeedback unique in the pantheon of EEG biofeedback interventions.

from standing potential to "DC potential shifts" and slowly changing potential to "slow cortical potentials" (Birbaumer, Elbert, Canavan, & Rockstroh, 1990;Elbert, Rockstroh, Lutzenberger, & Birbaumer, 1980).DC potential shifts are non-oscillatory fluctuations in amplitude measured in millivolts (Collura, 2009).This rise and fall of the large amplitude of the DC potential shift is frequent and impacts the smaller energy of the frequency domain measured in microvolts.
Slow Cortical Potentials (SCP) are changes of cortical polarization lasting several hundred milliseconds to several seconds.SCPs are related to the excitability level of underlying cortical regions.Negative SCP shifts reflect higher cortical excitability while positive shifts reflect reduced excitability or even inhibition.
SCP training has been employed, largely in Europe, for more than 30 years (Elbert et al., 1980).It has been used to train Epilepsy (Birbaumer et al., 1994), Brain-Computer Interface (Wolpaw, Birbaumer, McFarland, Pfurtscheller, & Vaughan, 2002), and ADHD (Birbaumer & Cohen, 2007;Heinrich, Gevensleben, Freisleder, Moll, & Rothenberger, 2004).SCP training is a "one size fits all protocol" with the majority of the training done at the vertex.As first developed, the client attempted to produce cortical excitation, a negative DC shift, in the case of ADHD; or cortical inhibition, a positive DC shift, in the case of Epilepsy over the course of many short trials (Birbaumer, 1999;Birbaumer et al., 1994).More recently SCP training has evolved to train in both negative and positive cortical shifts in the same session with proportions of negative and positive trials dependent on client presentation (Strehl et al., 2006).
Infra-slow Fluctuation (ISF) training is frequency-based training.These slow rhythms are influenced by changes in amplitude and polarization of the DC signal, but ISF neurofeedback is not SCP training.
ISF training owes its lineage to the early Beta/SMR training of Susan Othmer and EEG Spectrum (Kaiser & Othmer, 2000).That intervention was done with a single channel of EEG and an intra-hemispheric bipolar montage on the motor strip and temporal lobes.The starting frequency was in the 12-18 Hz range depending on the targeted hemisphere.The Othmers and others (Putman, Othmer, Othmer, & Pollock, 2005;Stokes & Lappin, 2010), modified this technique to include inter-hemispheric placements beginning on the temporal lobes.Instead of set reward bands, a 3 Hz window was shifted up or down contingent upon client response.The intervention produced immediate state shifts in the client.The trainer targeted state regulation in real time by discovering an optimum frequency through trial and error for each client.Success was defined by the immediate improvement in affect and arousal regulation in session and ultimately by generalized improvements in behavioral and state regulation in life.Over time, it became apparent that the vast majority of clients were finding an optimum clinical response at lower and lower frequencies until 2007, when the beginning frequency was established at 0-3 Hz.
It was at that time that a bifurcation in the field took place with one group of practitioners opting for an AC amplifier and another group, including the lead author, choosing a DC coupled encoder.Both groups continued the downward ramp of frequency optimization, narrowing the training window to less than 3 Hz.
As the optimum frequencies trained descended below 0.1 Hz, it became apparent to the DC amplifier users that optimum response was more readily achieved when training was executed with the amplifier in DC mode.The integration of the lower (DC) and higher (AC) energies produced enough "bounce" in the low alternating current domain to filter and to train the Ultradian Rhythms (< 0.01 Hz) (Palva & Palva, 2012) with more clarity and less noise in the signal.

The ISF Signal
Amplifier limitations that led to the elimination of lower frequencies in routine EEG determined the scope of brain research.As commercial DC coupled amplifiers became available, researchers began to address frequencies outside the traditional bandwidth of 0.5-50 Hz.Evidence increased that salient spontaneous EEG activity in human brain activity related to physiological and pathological behavior were being ignored.A group of researchers, largely in Europe, began to investigate this low phenomena.Their process became known as DC-EEG or FB-EEG (Full-band EEG).FB-EEG research suggests that the infra-slow is endogenously driven neuronal activity that is crucial in shaping brain network connectivity (Vanhatalo, Voipio, & Kaila, 2005).
For two decades researchers have proposed that neurons, glial cells, and blood may be regarded as compound generators of these infra-slow bioelectrical phenomena (Hughes, Lőrincz, Parri, & Crunelli, 2011;Zschocke & Speckmann, 1993).Thalamocortical neurons have been observed to exhibit robust infra-slow oscillations (ISOs), in vitro, at approximately 0.005-0.1 Hz (Lőrincz, Geall, Bao, Crunelli, & Hughes, 2009).After a reappraisal of in vivo and in vitro evidence, Crunelli and Hughes (2010) have proposed a three cardinal oscillator model that identifies one cortical and two thalamic sources of infra-slow frequencies.Astrocytes have recently been identified by Hughes et al. (2011) as a source of ISOs in the 0.003-0.1 frequency range.These researchers observed neurons in cat Thalamus succumbing to a cyclic inhibitory influence that they proposed was generated in the slow regime by Thalamocortical astrocytes.This lower frequency band is embedded in DC potential shifts in amplitude.A spectral display (Figure 1) clearly images the correspondence of the ISOs and DC standing potential shifts.As DC fluctuates on the mV scale, the frequency domain responds in the lower regime and at much higher frequencies as well.These cross frequency correlations are well documented (Keković, Sekulić, Podgorac, Mihaljev-Martinov, & Gebauer-Bukurov, 2012;Nir et al., 2008;Pfurtscheller, Daly, Bauernfeind, & Müller-Putz, 2012;Vanhatalo et al., 2004;Zschocke & Speckmann, 1993).It is the interaction of frequency and DC potential shift that drove the choice of the designation ISF training.The DC fluctuations were observed to drive the microvolt changes in the slow frequency regime and offer a target for feedback.In Figure 1 recurrent amplitude change in the ISF signal, sometimes only a fraction of a microvolt, which is the focus of reinforcement, not the return of the slow oscillation itself.It is important to note that when working with very slow signals, although it is possible to quantify the system response as a frequency, it may be equivalently considered as a timeconstant.In linear systems theory, it can be shown that for any filter there is a direct trade-off between frequency response and time-response, and that time and frequency can be considered as equivalent, alternative ways to view the system.The following figure (Figure 2) from Collura (1995) illustrates the relationship between the low-cutoff frequency and the time-constant.A lower cutoff frequency is associated with a longer time-constant.These are shown for a first-order filter, but are representative of any order filter.Specifically, for a first-order filter, the time-constant is defined (approximately) as: t = 1 / 2 * PI * fc .For example, a low-cut frequency of 0.3 Hz would have a time constant of 1 / 2 * PI * 0.3 = 0.53 seconds.The following Figure 3, of a vintage Grass amplifier, shows how this relationship is implicit in an amplifier.The selector for the low-frequency cutoff, with settings of 0.15, 0.3, 1, 3, and 10 Hz, is shown with a second set of indicators beneath, designating, for this amplifier, time-constants of 0.45, 0.24, 0.1, 0.04, and 0.015 seconds.
Because the filter is removing low frequencies, the time-constant reflects the rate at which the output tends to "recover" to the baseline.The lower the corner frequency, the longer it takes to recover.Therefore, lower cutoff frequencies are associated with the ability to "hold" the baseline longer, hence reflect longer-term processes.The time-constant shows that the input does not have to be cyclic or repetitive, but can be viewed as a transient, or fleeting, event, that is passed by the filter only if it reaches a certain magnitude of displacement within a certain time.With a DC amplifier, the output time-constant is infinite, reflecting the fact that the low cutoff frequency is 0.0000 to an arbitrary precision.

Amplification
ISF training uses Ag/AgCl electrodes and a DC coupled amplifier.As configured for ISF training, BrainMaster's Atlantis amplifier uses first-order Butterworth filters utilizing quadrature methods with an implicit envelope detection method that provides information faster than conventional peak-to-peak detection processes.Depending on the low-cutoff frequency applied in the software, the resulting filter will also have a corresponding timeconstant.For example, with a setting of 0.002 Hz as described in this report, the associated time-constant would be 175 seconds, or 2.92 minutes.This does not imply that the signal must oscillate with a period of 2.92 minutes, however.It simply indicates that when there is a shift in the baseline, the amplifier would require approximately 3 minutes to move the bulk of its recovery back to baseline.In other words, the amplifier "holds" onto the DC level of the value for a very long time, compared to the occurrences of each fluctuation or baseline shift.

Feedback Parametrics
The optimum frequency is reflected back to the client with two reward sounds, a higher tone when the amplitude increases more than 15% and a lower tone when the amplitude decreases more than 15% compared to a damped average of the signal.There is no sustained reward criteria; the client is rewarded the instant the reward parameters are met and continues for the duration of the condition.In addition there is no refractory period between rewards.The reward structure allows for the rapid transmission of information to the client concerning minute changes in amplitude of the ISF signal.
The ISF reward band typically starts at a low band-pass filter setting of 0 to a high band-pass filter setting of 0.002 Hz, and ranges to a high band-pass filter setting of 0.012 Hz.Additionally, in the basic protocol, the EEG is inhibited from 1 to 40 Hz in small bands: 1-3, 4-7, 8-12, 12-15, 15-20, 20-30, and 30-40 Hz.Each band is inhibited 3% of the time with an auto-thresholding function.These inhibits are fed back to the client via dimming of a DVD or the playing of a video game.Advanced protocols render simultaneous bipolar and referential montages allowing for combinations of ISF and synchrony training and ISF and referential enhancement.These sophisticated protocols are applied based on in-training z-score monitoring and pre/post QEEG analysis.

Optimizing Training
Clinical experience has made it clear that the best treatment response occurs when an Optimum Frequency (OF) is identified for each individual client.This process is undertaken for every client at either of two 10/20 sites: T4/P4 or T3/T4.The OF identification process may take place over several neurofeedback sessions and once identified rarely changes.Once the OF is known, frequency adjustments become necessary depending on the cortical area trained and the hemisphere involved.Some trainee outliers optimize above 0.012 and fewer still optimize below 0.002 with the vast majority between 0.002 and 0.012 Hz.The selection of cortical areas to be trained has traditionally been dictated by the relationship between client complaint and areas of cortical function.Recently the process of training site selection has been increasingly influenced by quantitative EEG (QEEG) assessments.
Optimization of frequency is achieved through a colloquy between therapist and client that leads to an optimum state of affect and arousal regulation in session.In addition, peripheral biofeedback measures such as heart rate, heart rate variability, Galvanic skin response, and skin temperature, are used to aid in the identification of autonomic balance and best response to the frequency parametrics.

Clinical Rationale
Researchers in Russia first identified the infra-slow rhythm nearly 60 years ago (Aladjalova, 1957;Aladjalova, 1964).Scientists at the Institute of Biophysics in Moscow implanted electrodes in the brains of rabbits and observed two general rhythms: one in the 6-8 second, 0.6-0.8Hz range; and the other slow periodic oscillation was identified in the 60-90 second, 0.023-0.0165Hz range.Aladjalova labeled these rhythms "infra-slow" to distinguish them from the "slow wave" of the EEG.
The infra-slow band was observed to increase in amplitude and frequency when experimental animals were subjected to stress-producing stimuli.The Russian researchers observed that poisoning, asphyxia, and irritation of subcortical structures intensified ISOs.
They theorized that the increase in amplitude of the ISOs reflected the Hypothalamus's reparative, parasympathetic, response.Supporting a role in the function of the neuroendocrine system, Marshall (Marshall, Mölle, Fehm, & Born, 2000) discovered an association between ISOs and Hypothalamic-Pituitary secretory activity.An increase in the amplitude of infra-slow periodicities between 64 and 320 seconds was coupled with the onset of the pulse of the Luteinizing hormone.This hormone, released by the Hypothalamus, triggers ovulation and stimulates the production of testosterone.
ISOs' prominence during sleep has been established.However, the functional significance of ISOs for sleep physiology remains unclear.The low regime has been postulated to coordinate activity between cortico-cortical networks (Buzsaki, 2006).In this way, the infraslow frequencies appear to organize a broad dissociation of cortical and sub-cortical activities during sleep (Picchioni et al., 2011) in areas that include the paramedian heteromodal cortices.Simultaneous positive associative correlations were established for the ISOs in the Cerebellum, Thalamus, Basil Ganglia, lateral neocortices, and Hippocampus.According to Picchioni, this suggests a role for ISOs in the organization of sleep-dependent neuroplastic processes generally and the consolidation of episodic memory specifically.
Recent research suggests that ISOs are embedded in and determinant of the excitability cycle of higher frequencies (Ko, Darvas, Poliakov, Ojemann, & Sorensen, 2011;Vanhatalo et al., 2004).Ko and workers revealed that the Default Mode Network (DMN) is characterized by high gamma band (65-110 Hz) coherence at infra-slow frequencies.This coherence, centered at 0.015 Hz, forms the neurophysiological basis of the DMN.Vanhatalo et al. (2004) established a role for the infra-slow frequencies in the control of gross cortical excitability.This research detected a close association between the ISOs and cyclic modulation of fast EEG activity.The phase of the ISO revealed a robust correlation with the amplitude of faster frequencies.Moreover, these low frequencies were observed to be tightly associated with K complexes, the largest event in the human EEG, and interictal epileptiform discharges: high amplitude paroxysmal activity.In fact, Vanhatalo became so convinced of the ISOs' centrality in cortex that he stated that any attempt to attenuate the signal eliminates the most salient features of the human EEG (Vanhatalo et al., 2005).Pfurtscheller (1976) reported the first observations of embedded frequencies in the human EEG, and observed ISOs in the alpha (8-14 Hz) frequency band.Later studies expanded on this work identifying human fluctuations in the theta, alpha, and beta (14-30 Hz) frequency bands that were power law autocorrelated in time scales from tens to hundreds of seconds exhibiting scale free, fractal like dynamics across the infra-slow frequency band (Ko et al., 2011;Linkenkaer-Hansen, Nikouline, Palva, & Ilmoniemi, 2001).Direct cortical recordings in animals and humans observed the amplitudes and coherence of frequencies from delta to high gamma (100-150 Hz) exhibit robust ISOs and spectral power-law scaling (Ko et al., 2011).
According to researchers, (Dong et al., 2012;Mairena et al., 2012;Monto, Palva, Voipio, & Palva, 2008) human behavioral performance is correlated with the ISFs in ongoing brain activity.Monto detected a strong correlation between a subject's ability to detect a sensory stimuli and the phase of the low frequency signal.Mairena and co-workers posited that the ISO is nested in six frequency bands and is related to fluctuations in sensory detection.
More broadly, ISO has been associated with the DMN of the human cerebral cortex (Liu, Fukunaga, de Zwart, & Duyn, 2010) and appears to be related to ADHD symptom status (Helps et al., 2010;Tye et al., 2012).Supporting this correlation, Broyd (Broyd, Helps, & Sonuga-Barke, 2011) found attention-induced deactivations of the ISF signal do not occur in Default Mode areas of cortex in subjects with ADHD, suggesting that they get "stuck" in selfreferential processing and are unable to turn off areas of cortex when appropriate.This resting brain network is anti-correlated with a task-positive network.The ISF reflects a toggling mechanism that switches between the DMN, the network of introspective and selfreferential thought, and the task positive network that responds to extrospective stimuli.
The ISO becomes intensified by agents that elicit a defense reaction similar to the response to "stress."Although the detailed physiological mechanisms underlying these Ultradian Rhythms have yet to be determined, some of the earliest research may provide data from which we can speculate on a precise mechanism of action of ISF training.In addition to its role in organizing neuronal networks, Aladjalova's research (Aladjalova, 1957(Aladjalova, , 1964) ) suggests the efficacy of ISF training may lie in the impact on the Hypothalamus.
The Hypothalamus is situated within the limbic system in the temporal lobes and plays an integral role in affective response as well as a vital role in maintaining homeostasis.It is the control center for many autonomic functions of the peripheral nervous system.Hypothalamic hormones control pituitary hormone secretion, which in turn manages adrenal secretion of epinephrine and norepinephrine, the hormones that organize sympathetic nervous system response.Known as the Hypothalamic-Pituitary-Adrenal (HPA) Axis, this organ system has feedback loops that promote reparative, parasympathetic nervous system, response as well.
ISF training places an electrode on the temporal lobes as one of two bipolar placements on the scalp.The other placement may be any of the other nineteen 10/20 sites.It is proposed that this configuration may explain the behavioral data of calming, arousal reduction, and attention promotion observed among trainees.Our clinical data suggest that a bipolar electrode configuration and an optimum frequency promote the normalization of activation, as well as the communication between and within neuronal networks.So theoretically it regulates the activation of brain areas linked in chronic autonomic stress and normalizes the communication between the hypothalamic and limbic areas, separating the non-temporal area from the HPA distress signal.Palva and Palva (2012) make a demarcation between the infra-slow (0.01-0.1 Hz) and the Ultradian rhythm (< 0.01 Hz) and refer to the former as ISFs.They point out in their research that the blood oxygenation-level dependent (BOLD) signals are correlated with constellations of brain regions that are very similar to networks that are correlated with the ISF signal.They note the direct association between ISFs in amplitude and behavioral performance with ISFs in the BOLD signal.The researchers concluded that ISFs arise from local cellular level mechanisms, as well as blood, and reflect the same underlying physiological phenomena: a superstructure of interrelating ISFs that regulates the integration within and decoupling between active neuronal networks.
We propose that ISF neurofeedback addresses this superstructure of interrelating neuronal networks.We submit that our pre-post QEEGs reveal changes in activation measures but especially in network dynamics as reflected by the coherence metric.The modification of information sharing between cortical areas produced by ISF training is consistent with research that demonstrates a role for the ISF in the regulation of neuronal networks.Addressing the integration of networks responsible for memory, affective response, autonomic regulation, and attention-to mention a few-may account for the reduction in symptom severity among our clients.
Our pre-post behavioral data is consistent with the theory that ISF regulates autonomic function.Appropriate affective behavior in a school setting was the general outcome for special needs children trained in this form of neurofeedback.ASD and emotionally disturbed children demonstrated improvements on the Child Behavior Checklist related to tantrums and aggressive behavior.Moreover, the ability to attend was improved as was social functioning.The pre-post training QEEG data is consistent with the ISO research in demonstrating an interaction with the phase relationships between cortical areas.In addition to improvements in absolute power, our data demonstrates substantial change in coherence relationships between cortical regions.The remediation of coherence values is resonant with the research that suggests a central role for the ISO in functional network communication (See the following case studies).

Clinical Data
What follows are clinical examples of ISF training.First we present pre-post ISF training behavioral data on a group of special needs children trained in a school setting.Two individual cases with pre-post QEEGs are then offered to demonstrate the remediation of network communication and absolute power distribution that results from ISF training.

Results of a School-Based Program
ISF neurofeedback was used as an intervention for a group of school-aged children in New York City.The population consisted of children with varying degrees of learning and developmental disabilities, including some who met criteria for high-functioning autism, others who met criteria for Asperger's syndrome, and still others with disorders of anxiety.All of the children also had sensory processing issues, some more severe than others.In addition, all of the participants were having significant difficulties meeting the demands of their school environment, despite being placed in supportive, specialized academic settings and receiving the services indicated on their Individual Education Plan (IEP).More information about each participant is included below.Admission to the neurofeedback program was based on parent or teacher referral, and students were excluded if they displayed signs of psychosis, uncontrolled seizures, recent traumatic brain injury, or if their medication regimen was too complex and/or unstable.
In total, 17 students were enrolled in the program, ranging in age from 6 to 15 years.In order to help conceptualize the experimental group and the effects of treatment, students were grouped into two broad clinical categories, Emotional Disorders (ED) or Pervasive Developmental Disorders (PDD).Participants in the ED group included students with a primary diagnosis of anxiety or another mood-related disorder, while those in the PDD group included children who were diagnosed to be on the autistic spectrum.Regardless of clinical category, all of the participants were having trouble meeting the academic and/or social demands of their school environment.In the most extreme cases, students were at serious risk of a forced transfer to a different school.Therefore, in addition to being grouped by their main diagnostic category, participants were also grouped according to the amount of difficulty they were having at school (i.e., high, moderate, or low risk) as shown in Table 1.Fourteen of the 17 students had a definite positive response to ISF neurofeedback training that involved either: (1) a significant reduction of behavioral disruptions, (2) a reduction or elimination of psychotropic medication, and/or (3) improved ability to sustain attention during class and continued academic progress.Of the remaining two students, one had a positive response that is confounded by the initiation of an SSRI at the beginning of the program (a selectively mute child who saw a tremendous improvement in symptoms after about only one week on the SSRI and two weeks with neurofeedback).The other two students were determined to be at status quo at the completion of treatment.For 11 of the 12 students for which CBCL data was available, improvements of greater than one standard deviation on relevant clinical scales were demonstrated.Data from each of these students is plotted in Figure 5. Case study 1.The client, a 12-year-old male, was diagnosed with Autism after undergoing a developmental regression at 15 months old.He was relatively high functioning in his communication and had good eye contact when we started working with him in June 2010.He was 9 years old at the beginning of treatment.His presenting complaintssevere OCD, perseverative thinking, hyperactivity, and significant behavioral problemsprevented him from continuing in a mainstream school setting.He had recently been assigned to a school for children with behavioral problems and was learning at three grade levels below his age.Initial trials with ISF, then limited to a 3-decimal place optimal frequency adjustment, resulted in a hyperactive response.
Initially he received Z-score training, which provided positive results, albeit slowly.Both parents observed other children receiving ISF training and noted the rapid shifts in behavior.Several trials of ISF training were performed at their request, all resulting in short-term hyperactivity but with bigger positive gains following.In November 2010, 4-decimal places optimal frequency adjustment were made available and the client was switched exclusively to ISF training with a suitable optimal frequency.He completed two ISF sessions each week and showed a rapid reduction in hyperactivity and behavioral issues.In March 2011 he received the "Student of the Month" award from his school for his exceptional behavior.Over the next year, ISF brain training reduced his level of OCD and perseverative thinking dramatically.At the end of 2012, his academic gap had closed; he tested between the 4th and 5th grade levels on the Structure of Intellect (SOI) rating scale and his OCD issues were resolved.His diagnosis has been changed to high-functioning Asperger's.Case study 2. The client, a 55-year-old African American male, presented with insomnia and PTSD.His early childhood was characterized by brutal, repetitive domestic violence between his parents.He witnessed his father's attempted murder of his mother.His father fractured his skull with a baseball bat.He was removed from the home by Child Services and placed in foster care at age eight.He was witness to beatings and gang rapes in group homes.The client was both shot and stabbed as an adult.He reported being a drug addict and alcoholic who had maintained abstinence for several years.At the beginning of training, he suffered with overwhelming anxiety, depression, and difficulty managing his anger.He reported sleeping with a rifle for protection.At the initiation of treatment, the client was extremely labile.His focus on fear and failure imagery had an obsessive quality that he felt powerless to control.
Treatment consisted of 31 sessions of ISF training targeting anxiety and depression.Areas trained included right pre-frontal and right parietal regions, bilateral temporal, and left pre-

Figure 1 .
Figure 1.Top graph labeled: Infra-slow Fluctuation uV.Images the Alternating Current ISF signal in microvolts, the white line, with the damped average of the signal, the green line.Bottom graph labeled: DC Fluctuation mV.Images the amplitude fluctuations of Direct current measured in milivolts, the white line, with the damped average of the signal, the green line.Notice the similarity between the rise and fall in amplitudes of the two signals.

Figure 2 .
Figure 2. Relationship between cutoff frequency (top) and holding time-constant (bottom).A lower cutoff frequency is associated with a longer time-constant.These are shown for a first-order filter, but are representative of any order filter.Specifically, for a first-order filter, the time-constant is defined (approximately) as: t = 1 / 2 * PI * fc .For example, a low-cut frequency of 0.3 Hz would have a time constant of 1 / 2 * PI * 0.3 = 0.53 seconds.The following Figure3, of a vintage Grass amplifier, shows how this relationship is implicit in an amplifier.The selector for the low-frequency cutoff, with settings of 0.15, 0.3, 1, 3, and 10 Hz, is shown with a second set of indicators beneath, designating, for this amplifier, time-constants of 0.45, 0.24, 0.1, 0.04, and 0.015 seconds.

Figure 3 .
Figure 3. Grass EEG amplifier showing combined "low frequency / time-constant" control, illustrating the interdependence of these two settings.

Figure 4 .
Figure 4. Pre-treatment breakdown of participants by diagnosis and presenting concern *ED = Emotional Disorder or **PDD = Pervasive Developmental Disorder.Results based on operationally defined construct (i.e., low, moderate, or high risk).

Figure 5 .
Figure 5. CBCL Results, Change on Marker of Primary Concern.CBCL results were available for 12 of the 17 students.The graph above plots the CBCL scaled score for each student's primary area of concern.There was an average improvement of 16 scaled score points, or 1.6 standard deviations of improvement.

Figure 6 .
Figure 6.Pre/post QEEGs depicting near global remediation of coherence in all bands, with normalization of the deviant absolute power in the high beta band at the frontal midline.
, the morphology of the two signals are shown compared to the damped average of each signal.DC is measured in millivolts, while ISF is rendered in microvolts.It is this

Table 2
Summary of Treatment Population