High Alpha Activity Research Articles

An EEG biofeedback protocol for affective disorders.

INTRODUCTION Despite our own older work which showed that biofeedback with somatosensory evoked EEG potentials can have profound effects on pain perception in rats and it seemed to us quite a leap to think that an application of EEG biofeedback could be effective in treatment of depression and other affective disorders. Yet the logic of developing such an intervention would be no different than that which was used in our work in the pain modality: In that work, we were aware of-a sizable literature documenting evoked EEG potential (EP) correlates of We reasoned simply that if a large value of a particular EP component accompanied intense pain, whereas a smaller value accompanied no pain or analgesia, then if one could train individuals to reduce the particular EP, one ought to see reductions in perceived pain. This approach yielded very promising Thus it seemed to us that a reliable EEG index of affect could be found, then we would be in a position to develop an EEG biofeedback protocol for depression. However, until the recent publication of work from R. J. Davidson's laboratory,g there were no documented reliable indices of affect in the waking EEG. Based on evidence from the neurology literature, Davidson and associates hypothesized that the right frontal cortex contained a neural system mediating negative emotion and avoidance behavior, whereas, in contrast, the left frontal cortex contained a neural system mediating positive affect and approach behavior. An active cortex is known to show higher (13-30 Hz) frequencies in a low amplitude, desynchronized EEG, whereas an idling or inactive cortex is known to show lower (8-12 Hz) frequencies of synchronous (sinusoidal) higher amplitude activity. Davidson and colleagues thus hypothesized that positive emotion should correlate with high beta and low alpha activity in the left frontal cortex and with low beta and high alpha activity in the right frontal cortex. Negative emotion would correlate with the reverse pattern of cortical activity: high left frontal alpha, low lefi frontal beta, high right frontal beta, and low right frontal alpha. Because there are harmonics of electromyographic activity reaching down to the beta range, which could be therefore mistaken as beta, many researchers have focused on the alpha (inverse) indices of emotion. (It is possible to utilize beta, but it requires added steps to correct for electromyographic artifact.) In a series of ingenious, original experiments, Davidson and colleagues provided a strong set of evidence that cortical activation asymmetry as inversely indexed by alpha power or magnitude, was a reliable correlate of positive and negative emotion. The asymmetry metric developed by the Davidson group will be referred to here as the asymmetry score =A, = log R log L where R is alpha power at cortical site F, and L is alpha power at cortical site F, . It is also possible to define an asymmetry score as A, = (R-URtL). Although A, and A, are not mathematically equivalent, they correlate very highly (2 .98).lD1' What has been generally found is that higher A, or A, scores go with positive affect and lower A, or A, scores go with negative affect. (Hereafter, the unsubscripted term A-score will be used to refer to generic alpha asymmetry indexed by either A, orA2). The former condition means greater left frontal activation; the latter means greater right frontal activation. The term relatively is used here because in any individual case, one cannot say from an Ascore whether the critical effects are in the left versus right cortex, or both, since A-scores combine R and L. Davidson and co11eagues9 did a variety of studies to support their hypothesis. For example, they showed that a person's resting frontal alpha asymmetry predicted their affective responses to emotionally positive and negative film clips.12 They also showed that rewards and punishments led to differential asymmetry response^,'^ and showed that facial expressions of emotion were systematically related to asymmetry scores.914 Most relevant to this article, (1) Henriques and Dav ids~n '~ in 1990 showed that currently depressed persons have left frontal hypoactivation (lower A,-scores) in comparison with never depressed persons: (2) Henriques and Davidson16 in 1991 showed that previously depressed but now remitted persons show also a relative left frontal hypoactivation in comparison with never depressed persons. Gotlib, Ranganath, and Rosenfeld in 1998 replicated and extended this finding, in one study, by comparing three groups: currently depressed, formerly depressed,

197 Attention and disattention (hypnotic analgesia) to painful somatosensory tens stimuli differentially affects brain dynamics: A functional magnetic resonance imaging study

EEG correlates of self-generated happy and sad emotions during counterbalanced conditions of waking and hypnosis were investigated in 16 low (‘lows’) and 15 highly (‘highs’) hypnotizable men, as assessed by the Harvard Group Scale of Hypnotic Susceptibility and the Stanford Hypnotic Susceptibility Scale, Form C. Using log mean spectral magnitude, 11 frequency bands (3.5–42 Hz) were evaluated at frontal (F3, F4), central (C3, C4), and parietal (P3, P4) regions. As anticipated, only parietal hemispheric differences in low alpha activity (7.5–9.45 Hz) differentiated between emotions, whereas mid and high alpha activity (9.5–13.45 Hz) did not. There was significantly less low alpha activity in right parietal (P4) in sad than happy emotions, supportive of prior research showing relatively greater right hemispheric involvement in negative than positive emotions. Yet, overall there was more low alpha activity in the left parietal (P3) region. During sadness only in waking, low beta (13.5–15.45 Hz) activity was greater in the right than left frontal region, greater in the left than right central region, and similar in both hemispheres in the parietal region. As anticipated, in comparison to lows, highs showed significantly greater hemispheric asymmetries (right greater than left) in the parietal region in high theta (5.5–7.45 Hz), high alpha (11.5–13.45 Hz), and beta activity between 16.5 and 25 Hz — all frequency bands that are associated with sustained attentional processing. Results support prior research (for reviews, see Crawford, 1994a; Crawford and Gruzelier, 1992) that highs have greater sustained attentional abilities than do lows, which is reflected in different regional brain dynamics. Future EEG research needs to address narrower EEG frequency bands, as well as consider the moderating effects of hypnotic susceptibility level in observed hemispheric asymmetries.

Self-generated happy and sad emotions in low and highly hypnotizable persons during waking and hypnosis: laterality and regional EEG activity differences

EEG correlates of self-generated happy and sad emotions during counterbalanced conditions of waking and hypnosis were investigated in 16 low (‘lows’) and 15 highly (‘highs’) hypnotizable men, as assessed by the Harvard Group Scale of Hypnotic Susceptibility and the Stanford Hypnotic Susceptibility Scale, Form C. Using log mean spectral magnitude, 11 frequency bands (3.5–42 Hz) were evaluated at frontal (F3, F4), central (C3, C4), and parietal (P3, P4) regions. As anticipated, only parietal hemispheric differences in low alpha activity (7.5–9.45 Hz) differentiated between emotions, whereas mid and high alpha activity (9.5–13.45 Hz) did not. There was significantly less low alpha activity in right parietal (P4) in sad than happy emotions, supportive of prior research showing relatively greater right hemispheric involvement in negative than positive emotions. Yet, overall there was more low alpha activity in the left parietal (P3) region. During sadness only in waking, low beta (13.5–15.45 Hz) activity was greater in the right than left frontal region, greater in the left than right central region, and similar in both hemispheres in the parietal region. As anticipated, in comparison to lows, highs showed significantly greater hemispheric asymmetries (right greater than left) in the parietal region in high theta (5.5–7.45 Hz), high alpha (11.5–13.45 Hz), and beta activity between 16.5 and 25 Hz — all frequency bands that are associated with sustained attentional processing. Results support prior research (for reviews, see Crawford, 1994a; Crawford and Gruzelier, 1992) that highs have greater sustained attentional abilities than do lows, which is reflected in different regional brain dynamics. Future EEG research needs to address narrower EEG frequency bands, as well as consider the moderating effects of hypnotic susceptibility level in observed hemispheric asymmetries.

Uranium-series disequilibrium, sedimentation, diatom frustules, and paleoclimate change in Lake Baikal

The large volume of water, approximately one-fifth of the total surface fresh water on the planet, contained in Lake Baikal in southeastern Siberia is distinguished by having a relatively high concentration of uranium (ca. 2 n M), and, together with the surface sediments, an unusually high 234U 238U alpha activity ratio of 1.95. About 80% of the input of uranium to the lake, with a 234U 238U ratio of 2.0, comes from the Selenga River. Profiles of uranium, as well as the extent of isotopic disequilibrium in a 9 m sediment core collected on Academic Ridge, generally show high values during interglacial periods corresponding to high diatom frustule numbers (DiFr) and biogenic silica (BSi) data that have been reported elsewhere. During glacial periods (low DiFr and BSi), uranium progeny ( 234U and 230Th) were in secular equilibrium with low concentrations of their parent 238U. Radionuclide distributions were interpreted in terms of a quantitative model allowing for adsorption of riverine inputs of uranium onto two classes of sedimenting particles with differing 238U 232Th ratios and uranium progeny in secular equilibrium. If the 234U 238U activity ratio of adsorbed uranium has remained constant, mean sedimentation rates can be independently estimated as 3.6 ± 0.6 and 3.7 ± 0.9 cm · kyr −1 for the decay of 234U and in-growth of 230Th, respectively. These rates are consistent with a mean rate of 3.76 cm · kyr −1, calculated by optimization of the correspondence between adsorbed 238U and δ 18O in dated oceanic sediments. The adsorbed uranium apparently tracks variable river flow during interglacials and is drastically reduced during periods of glaciation. Evidently, uranium has not been significantly redistributed within Baikal sediments over at least the past 250 kyr and is a unique, biologically non-essential, tracer for climate-sensitive processes, which provide their own internal geochronometers, potentially useful for ages up to 1 Myr BP.

EEG Biofeedback for the Enhancement of Attentional Processing in Normal College Students

College students diagnosed as free of any neurological or attention deficit disorder received EEG biofeedback to enhance beta (16-22 hertz) activity while simultaneously inhibiting high theta and low alpha (6-10 hertz) activity in order to evaluate improvements in attentional measures. Following short-term treatment (mean number of sessions=20), subjects were evaluated as either learners or non-learners based upon standard preversus post-treatment neurofeedback measures. Attention quotients taken from pre and post-treatment measurements using the Intermediate Visual and Auditory (IVA) Continuous Performance Test identified significant improvements in attentional measures in learners, while non-learners showed no significant improvements. Results suggest that some normal young adults can learn to increase EEG activity associated with improved attention. Twenty sessions, however, even for this population may represent the lower limit for achieving significant improvement.

Induction of cyclooxygenase and prostaglandin E2 production by the bovine pre-embryo

A study was conducted to determine the induction of cyclooxygenase production in the cleaved and non-cleaved oocyte and to measure the secretion of prostaglandin E2 (PGE2), PGF2 alpha and tumour necrosis factor-alpha (TNF alpha) in the conditioned medium of non-mature oocytes (denuded), mature oocytes (oocyte-cumulus complex), cleaved oocytes, and non-cleaved oocytes (mature oocytes incubated in the absence of sperm). Cyclooxygenase was readily detectable in 48-h cleaved oocytes whereas the signal for the enzyme in the non-cleaved oocytes was weak or undetectable. Cyclooxygenase expression in the cleaved oocytes was transient and enzyme concentrations at the early morula stage (72 h) were low. Measurable amounts of both PGE2 and TNF alpha were secreted during the first 24 h of maturation and 6 h after fertilization, whereas PGF2 alpha was undetectable at these times. There was a dramatic enhancement in PGE2, PGF2 alpha and TNF alpha secretion 48 h after fertilization. At 72 h after fertilization, PGE2 concentrations were much lower and PGF2 alpha was again undetectable which corresponded to a low concentration of cyclooxygenase. In contrast, high TNF alpha activity continued to be detected even 72 h after fertilization. It is possible that the induction of the production of cyclooxygenase and the secretion of PGs and TNF alpha by fertilized oocytes at specific times after fertilization plays a role in the regulation of embryonic development, maternal immunological recognition of pregnancy, and the maintenance of a suitable hormonal environment for embryonic viability.

Cerebral asymmetries and stimulus intensity relationships in EEG spectra of VEPs in unmedicated schizophrenic patients: relationships with Active and Withdrawn syndromes

Active and Withdrawn syndromes in schizophrenia have been associated with different patterns of lateral asymmetry: higher left than right hemisphere activity in the Active syndrome and the opposite pattern in the Withdrawn syndrome. Here validation was explored with a power spectral analysis of the visual evoked potential recorded to flashes of five different intensities from primary sensory occipital cortex (O1, O2) and from temporal (T3, T4) cortex. Unmedicated schizophrenic patients were categorised as Active or Withdrawn syndrome by clinical ratings. Pattern of lateral asymmetry of electrodermal orienting responses was recorded and was found to be as predicted: larger on the left than right hand in the Active syndrome with the opposite pattern in the Withdrawn syndrome. Normal controls were also examined. At occipital placements the main results were in beta (18–22 Hz) in which (1), syndromes showed opposite asymmetry patterns consistent with predictions: higher power on the left in the Active syndrome and on the right in the Withdrawn syndrome and (2), there was an absence of normal stimulus intensity/beta power relations in the Withdrawn syndrome. The Active syndrome showed abnormal relations at the temporal location, reflected in high alpha activity (10–14 Hz), together with an abnormal asymmetry in 2–6 Hz activity in the direction of more slow wave activity in the right hemisphere, a lateral asymmetry consistent with the model. When compared with the controls the Withdrawn syndrome was dysfunctional at lower, sensory cortex, levels of processing while the Active syndrome was dysfunctional at higher, temporal cortex, stages of processing. Schizophrenic patients as a group were characterised by abnormal desynchronisation of left temporal activity.

Analysis of human hair and lung samples from contaminated and non-contaminated regions of belorussia using the solid state nucleuar track detection technique

Five human hair and five lung samples, received towards the end of 1990 from supposedly contaminated and non-contaminated regions around the site of the Chernobyl nuclear disaster of April 1986, were analysed using the Solid State Nuclear Track Detection (SSNTD) technique. The samples, which included control specimens from the former Soviet Union as well as a British control hair sample, were prepared by ashing at 300°C, and were found to have levels of alpha-activity ranging from 21 to 62 Bq kg −1 for the hair samples, and from 3 to 66 Bq kg −1 for the solid lung tissue. These levels are broadly comparable to those expected in a normal healthy subject. Statistical analysis indicates that the 62 Bq kg −1 level for one of the hair samples is the only statistically significant result ( p < 0.01) showing high alpha-activity. These findings can, therefore, be said to corroborate the IAEA Report on Chernobyl (IAEA, 1991), which suggests that the ill effects found in the area are primarily due to factors other than abnormally high levels of radiation.

Analysis of human hair and lung samples from contaminated and non-contaminated regions of Belorussia using the solid state nuclear track detection technique

Five human hair and five lung samples, received towards the end of 1990 from supposedly contaminated and non-contaminated regions around the site of the Chernobyl nuclear disaster of April 1986, were analysed using the Solid State Nuclear Track Detection (SSNTD) technique. The samples, which included control specimens from the former Soviet Union as well as a British control hair sample, were prepared by ashing at 300°C, and were found to have levels of alpha-activity ranging from 21 to 62 Bq kg −1 for the hair samples, and from 3 to 66 Bq kg −1 for the solid lung tissue. These levels are broadly comparable to those expected in a normal healthy subject. Statistical analysis indicates that the 62 Bq kg −1 level for one of the hair samples is the only statistically significant result ( p < 0.01) showing high alpha-activity. These findings can, therefore, be said to corroborate the IAEA Report on Chernobyl (IAEA, 1991), which suggests that the ill effects found in the area are primarily due to factors other than abnormally high levels of radiation.

Radon transport into a detached one-story house with a basement

We describe the results of a five-month study during which 222Rn (radon) concentration, air- exchange (or ventilation) rate, and weather and radon source parameters were continuously monitored in a house near Chicago, with a view to accounting for the radon entry rate. The results suggest that the basement sump and perimeter drain-tile system played an important role in influencing the radon entry rate and that pressure-driven flow was more important than diffusion as a mechanism for radon entry. For the first 15 weeks of the study period the mean indoor radon concentration and air-exchange rate were 2.6 pCiℓ −1 (96 Bq m −3) and 0.22h −1, respectively; both parameters varied over a wide range. Radon concentration measured at the sump cover varied bimodally between 0 and 10 pCiℓ −1 (0–400 Bqm −3) and 300–700 pCiℓ −1 (10,000–30,000 Bq m −3). These two modes corresponded well to periods of low and high indoor radon concentration; average indoor concentrations for these periods were 1.5 and 6.5 pCiℓ −1 (55 and 240 Bq m −3), respectively. For data sorted into two groups according to radon activity at the sump, the indoor radon concentration showed little dependence on air-exchange rate. This result is accounted for by a model in which the radon entry rate, determined by mass balance, has two components—one diffusive, the other a pressure-driven flow component which is presumed to be proportional to the air-exchange rate. In fitting this model to the data we found that (1) the flow component dominated the diffusive component for periods of both high and low activity at the sump and (2) the magnitude of the diffusive component agreed well with the expected contributions of radon emanating from concrete and soil and diffusing into the house. To account for the flow component, we hypothesize that pressure drives air carrying a high concentration of radon generated in the soil, either through the bulk of the soil or along the outside of the basement walls, then into the basement through cracks and openings. During the final six weeks of the study, measurements were made with the water level in the sump maintained first below, then above the entrance of the pipe connected to the perimeter drain tile system. Average indoor radon concentrations during these two periods were 10.6 and 3.5 pCiℓ −1 (390 and 130 Bq m −3), respectively. The relatively high latter value compared with the mean for the first 15 weeks, combined with the observation of intervals of high airborne alpha activity at the sump during this period, suggest that the level of water in the sump does not, by itself, account for the variation in alpha activity at the sump that we had previously observed. Fireplace operation substantially increased the air-exchange rate, but had only a small effect on indoor radon concentration, providing corroborative evidence that pressure-driven flow is an important mechanism for radon entry into this house.

Lucid dreaming and alpha activity: a preliminary report.

10 good dream recallers spent 2 nights in the sleep lab during which they were awakened 4 times per night from REM sleep, twice during their highest alpha activity in REM, and twice during low REM alpha. 5 were given alpha feedback training prior to sleep onset. Arousals from high alpha REM sleep yielded significantly higher lucidity ratings. Alpha feedback had no effect upon lucidity or REM alpha levels. Similarities between lucid dreams and meditative phenomena are discussed.

Terminal deoxynucleotidyl transferase activity and cell surface antigens of two unique cell lines (NALM-1 and BALM-2) of human leukemic origin.

Two unique cell lines, NALM-1 and BALM-2 derived from lymphoblast-like cells of chronic myelogenous leukemia and rare B cell acute lymphoblastic leukemia patients, respectively, were compared with fresh parent cells from the patients and with a Philadelphia chromosome positive K-562 cell line previously established from a chronic myelogenous leukemia patient in blastic phase. NALM-1 resembled the parent cells in the presence of Philadelphia chromosome, non-T/non-B acute lymphoblastic leukemia specific antigens and lack of T or B cell markers, whereas BALB-2, like the parent cells, had two chromosome markers and bore kappa, delta and mu immunoglobulins. NALM-1 lacked Epstein-Barr virus genome, whereas BALM-2 showed the presence of Epstein-Barr virus genome. K-562 cells lacked all the antigen markers examined. All cells had high DNA polymerase alpha activity and low DNA polymerase gamma activity. NALM-1, like the parent cells and unlike K-562 cells, had high terminal deoxynucleotidyl transferase activity of about 200 mu/mg DNA, whereas BALM-2, like its parent cells, had terminal deoxynucleotidyl transferase activity of 1-2 mu/mg DNA (1 u = 1 nmole Mn++-dGTP/h on dA12-18 initiator). Terminal deoxynucleotidyl transferase was characterized by its chromatographic and sedimentation behavior, thermal sensitivity and specific inhibition by streptolydigin and terminal deoxynucleotidyl transferase antisera. These results indicate that NALM-1 and K-562 may represent different phenotypes of cells in CML blastic crisis. Moreover, NALM-1 and BALM-2 seem to have retained the characteristics of original leukemic cells from which they may have been derived.

Feedback for high EEG alpha does not maintain performance or mood during sleep loss.

ABSTRACTCan performance and mood during sleep loss be maintained by self‐induced high EEG alpha activity? In a previous study, most of the performance and mood measures showed sleep‐loss impairment regardless of EEG alpha level, but attention and reported sleepiness were less impaired for the high‐alpha group (although the differences were of doubtful significance). A constructive replication was carried out. In Group A (N=10) auditory feedback was contingent on high alpha, and in Group B (N=10) auditory feedback was contingent on low alpha and low theta. All subjects were repeatedly measured on auditory vigilance, addition, immediate recall, and feelings of sleepiness for 40 hrs during which no sleep was permitted. Sixty min of EEG feedback were given during each block of 220 min. Group A did produce significantly more alpha for the first 24 hrs but this difference was not maintained. Both groups had significant sleep‐loss impairment on all measures. There were no significant differences between the groups in the amount of impairment. Self‐enhanced EEG alpha activity does not prevent impairment of performance or mood during sleep loss.

Alpha wave phase and alpha attenuation

1. 1. Previous reports indicated that phase of the occipital alpha wave and cortical excitability are related. Habituation of the alpha attenuation response (AAR) to both visual and auditory stimuli was examined with a view to determining whether different degrees of habituation would be demonstrated when stimuli are presented at different phases of the alpha wave. In addition, contingent alpha attenuation in a paired click-flash sequence was examined. 2. 2. Subjects with abundant, fairly high amplitude alpha activity were assigned randomly to one of five groups determined by the point on the alpha wave at which they were stimulated. The groups were further divided into four subgroups, each of which had the procedure repeated with stimuli presented at one of the other points on the alpha wave. Stimuli were delivered by an automatic alpha recognition device using zero crossing detection. Forty presentations of single and paired stimuli were presented during runs of alpha activity with at least 5 sec and one unstimulated train of alpha waves between successive stimuli. 3. 3. The duration of the AAR decreased with successive blocks of trials to the least extent and most slowly for subjects stimulated randomly. Duration decreased most rapidly for the group stimulated at the peak of alpha wave with clicks and for the group stimulated midway on the up-going portion of the wave with flashes. In the paired condition, there was a tendency for those subjects stimulated at the trough of the wave to reach criterion in the fewest number of trials. 4. 4. The results of the present study suggest that phase of the alpha wave is associated with cortical excitability. When phase is corrected for conduction time, most rapid habituation to the flash and click stimuli occurs when the alpha cycle is moving toward surface positivity. However, the trend toward most rapid contingent AAR occurs when the contingent stimulus is presented as the alpha phase is moving toward surface negativity.

Spontaneous awake eeg patterns in three lines of primate evolution

Awake scalp EEGs were recorded from 170 restrained animals, including tree shrews, prosimians, New World simians, and Old World simians. Percent scores were determined for alpha and beta range frequencies and the alpha-beta ratios were compared. It was determined that: (a) the tree shrew has a highly variable and disorganized EEG with no particular frequency range consistently represented, whereas the true monkeys show relatively consistent and stable frequency patterns; (b) high alpha activity appears to be related to level of evolutionary development; and (c) low alpha or high beta activity is not related to phylogeny but appears to be related to life style.

Intensity and coherence contours during self-regulated high alpha activity

Spectral intensity and coherence analysis of EEG activity during rest and during a period of self-regulated high alpha in two subjects indicate that: (1) Slow frontal activity, which is due primarily to eye movements, is less intense during successful alpha regulation than during baselines. (2) There is little evidence for increased intensity in frequency ranges other than the alpha range during alpha regulation. (3) Occipital alpha tends to be more coherent with frontal than with temporal alpha during occipital alpha regulation.

Bispectrum analysis of electroencephalogram signals during waking and sleeping.

The degree of interaction of component waves making up a single electroencephalogram trace was strongly correlated with alpha activity, lead placement, and state of consciousness. Significant quadratic coupling of the waves was found only for awake subjects with high alpha activity. For these subjects about 50 percent of beta activity can be attributed to harmonic coupling with the alpha peak. During sleep, the degree of interaction was of borderline significance and did not follow a consistent pattern with respect to subject, frequency, state, or lead.

The naturally occurring alpha-ray activity of foods.

Most of the activity is due to members of the thorium and radium series. There is a factor of 20,000 between the most active and least active foods. The most active food so far measured is the Brazil nut; breakfast cereals have the next highest alpha activity. In general, values in milk products, fruits, and vegetables are low. The alpha activity seems to increase with the phosphorus content of foods. In general, an adequate diet will not contain less than 2 x 10/ sup -12/ c of alpha /day. (auth)