Increase In Alpha Frequency Research Articles

Development of the Alpha Rhythm Is Linked to Visual White Matter Pathways and Visual Detection Performance.

Alpha is the strongest electrophysiological rhythm in awake humans at rest. Despite its predominance in the EEG signal, large variations can be observed in alpha properties during development, with an increase in alpha frequency over childhood and adulthood. Here, we tested the hypothesis that these changes in alpha rhythm are related to the maturation of visual white matter pathways. We capitalized on a large diffusion MRI (dMRI)-EEG dataset (dMRI n = 2,747, EEG n = 2,561) of children and adolescents of either sex (age range, 5-21 years old) and showed that maturation of the optic radiation specifically accounts for developmental changes of alpha frequency. Behavioral analyses also confirmed that variations of alpha frequency are related to maturational changes in visual perception. The present findings demonstrate the close link between developmental variations in white matter tissue properties, electrophysiological responses, and behavior.

Interferential Current Ability to Change the Pattern of Brain Activity in Patients With Nonspecific Low Back Pain

Objectives: Chronic low back pain (CLBP), along with physical limitations that affect the quality of life, is one of the most important problems in the health community. The pain causes a wide range of structural, functional, and neurological changes in the brain. However, these changes have not been well studied, as brain changes in other chronic pains. This study aimed to evaluate the changes in the electroencephalogram (EEG) of patients with nonspecific CLBP, and also to evaluate the effects of interferential current (IFC), as one of the common treatment methods in these patients, on the EEG. Methods: This randomized control trial was performed in the Physiotherapy Clinic of Rehabilitation Faculty of Tabriz University of Medical Sciences from July 2021 to February 2022. A total of 20 patients with nonspecific CLBP and 20 healthy individuals participated in this study. Healthy subjects were in the control group, and the patients were randomly divided into two groups: intervention and placebo. Participants’ EEG and pain intensity were recorded before and after one session of IFC. Results: The results of statistical analyses to compare the EEG of patients and healthy individuals did not show a significant difference between the two groups. The results of statistical tests to evaluate the effects of IFC on participants’ EEG showed a significant increase in alpha frequency in all three groups. In addition, a significant increase in theta frequency was recorded in the placebo group, and an increase in the beta frequency in the intervention group. Pain intensity showed a significant decrease only in the intervention group. Discussion: The results of this study suggest that changes in EEG in patients with low back pain may be related to the severity of pain and neurological involvement. In addition, the increased power of EEG following the application of IFC may be due to sensory stimulation of the skin surface.

Caffeine effects on resting-state arousal in children

From previous work in our laboratory, increases in skin conductance level (SCL), together with global (across-scalp) decreases in electroencephalogram (EEG) alpha power and increases in alpha frequency, are useful indices of arousal increase, and here we sought to identify changes in these indices with caffeine ingestion in children. We explored the effects of a single oral dose of caffeine (80 mg) in a randomised double-blind placebo-controlled repeated-measures cross-over study. Thirty healthy children aged between 8 and 13 years (mean age 10.5 years; 11 females) participated in two sessions, 1 week apart. EEG and SCL from a 3 min eyes-closed epoch, commencing approximately 30 min after ingestion of caffeine or placebo, were examined. Caffeine was associated with increased SCL, and a global reduction in EEG power in the theta and alpha bands, as well as topographically-focused reductions in delta and beta power, and a focal increase in alpha frequency. Only global alpha level demonstrated the expected inverse relationship with SCL in both placebo and caffeine conditions. These results are generally consistent with recent electrodermal and EEG studies of arousal. Together with our previous adult data, they indicate that caffeine can be used to increase arousal in both adults and children, without the potential confounds associated with varying task demands. Caffeine appears useful as a simple tool for manipulating arousal in studies exploring its role in physiological and behavioural functioning. This may be helpful in determining the role of hypothetical arousal anomalies in syndromes such as attention-deficit/hyperactivity disorder.

Caffeine effects on resting-state arousal

Objective This study examined the use of caffeine to manipulate arousal level without the confounds associated with task-related activation. From previous work in our laboratory, an increase in skin conductance level (SCL) and EEG alpha frequency, together with a global decrease in alpha power, were used as markers of arousal increase, and we sought to identify these effects with caffeine ingestion. Methods We examined the effect of a single oral dose of caffeine (250 mg) in a randomised double-blind placebo-controlled repeated-measures cross-over study. Eighteen healthy university students (mean age 21 years; 13/18 females) participated in two sessions 1 week apart. EEG and autonomic data (SCL, heart rate, systolic and diastolic blood pressure, and respiration rate) from a 2 min eyes-closed epoch, commencing approximately 30 min after ingestion of caffeine or placebo, were examined. Results Caffeine was associated with increased SCL, a global reduction in EEG power in the alpha band, and a global increase in alpha frequency. There were no cardiovascular effects. Conclusions The positive results are consistent with recent electrodermal and EEG studies of arousal and suggest that caffeine may be utilised as a task-free means of manipulating arousal in future investigations. Further work is necessary to clarify the absence of cardiovascular effects, and to integrate those data with emerging conceptualisations of arousal and activation. Significance The present data support the use of caffeine as a simple tool to explore the role of arousal in both normal and atypical functioning, and this may be useful in determining the validity and importance of supposed hyper- or hypo-arousal in such syndromes as attention-deficit/hyperactivity disorder (AD/HD).

Mecamylamine reduces some EEG effects of nicotine chewing gum in humans

Spontaneous EEG was recorded in nine cigarette smokers who had been abstinent from tobacco for 12 hr. Subjects were treated with a capsule containing either centrally acting nicotine blocker, mecamylamine (10 mg), or placebo. At each of three 60-min intervals after the capsule was ingested, the subjects chewed two pieces of gum containing a total of 0, 4 or 8 mg of nicotine. Nicotine and mecamylamine dose combinations were randomized across subjects. Two three-minute periods of spontaneous EEG were recorded before the capsule and before and after gum chewing from bipolar electrode montages at the following positions: Cz-T5, Cz-T6, Cz-F7 and Cz-F8. During one period the subjects relaxed with eyes closed, in the other period they performed a math task with eyes open. When the drugs were given individually, mecamylamine decreased beta power and nicotine gum (4 and 8 mg) increased alpha frequency. Mecamylamine pretreatment prevented the increase in alpha frequency caused by the 4 mg gum dose but not the 8 mg dose. Alpha power was increased by the 8 mg gum dose and that increase was prevented by mecamylamine. Self-reported ratings of the "strength" of the gum were significantly diminished by mecamylamine pretreatment. The data are consistent with the results of earlier studies which indicate that the effects of tobacco administration and withdrawal are mediated by central actions of nicotine.

Relation of alpha frequency to amplitude variability.

Kleitman (4) has suggested that the frequency of the alpha EEG partern is related to level of consciousness. He presented studies which showed a decrease in alpha frequency during sensory isolation, an increase in alpha frequency in hyperthermia, a decrease in alpha frequency associated with hypothyroidism, and an association of alpha frequency and body temperature within the individual. Other evidence has suggested that the level of consciousness is related to the variability of the amplitude of the EEG (1, 2, 3, 5, 6). To investigate possible association of alpha frequency and amplitude variation of the normal EEG in a wakeful state was the aim of this study. The EEGs of 50 paid normal males (ages 17 to 62, inclusive), about high school educational level, were individually recorded. Each recording session was of 15 min. duration and held in a sound attenuated room with S in a supine position with closed eyes. A solidstate integrator and a Beckman-Offner Type R Polygraph were used to record the EEG from

Effects of carbon dioxide on the alpha frequency and reaction time in humans

Summary The effects of acute exposure (5 min) to carbon dioxide (0–7.9%) on the EEGs and reaction times of five humans were investigated. Alpha frequency and alpha amplitude were recorded from the central and from the occipitalparietal areas of the scalp while subjects reacted with their right index finger to flashes of light. Variance analyses indicated that the percentage CO 2 inhaled significantly affected alpha frequency and reaction time. Alpha frequency and reaction time were significantly faster under the 0–5.5% CO 2 conditions than under the 7.9% CO 2 condition. A slight increase in alpha frequency and decrease in reaction time were evident under the 3.5 and 5.5% CO 2 conditions as compared to the 0 and 1.5% CO 2 conditions.

Studies of periodic catatonia — I: Blood levels of protein-bound iodine and urinary excretion of vanillyl-mandelic acid in relation to clinical course

SINCE 1927 extensive sleep studies of patients with periodic catatonia have been carried out in this 1aboratory.l Sleep was recorded by means of a seismograph called ‘accelerograph Devik’. This apparatus records continuously all the patient’s movements while he is in bed. These studies concluded that all the patients with periodic catatonia had a moderate to severe sleep disturbance at the beginning or in the middle of their psychotic phases. The urinary catecholamine metabolites of several patients with periodic catatonia have been examined previously but not the catecholamines themselves. During the psychotic phase the excretions of both normetanephrine and metanephrine as well as 3-methoxy-4hydroxy-mandelic acid were all elevated.2-4 In order to examine the psychotic phase further, longitudinal EEG studies were carried out on three cases with periodic catatonia.5 These records showed a definite increase in alpha frequency and a decreased alpha amplitude during the active phase corresponding to the excretion of normetanephrine. Recently, extensive studies of sleep EEG in acute schizophrenic patients have been reported.6,7 Some actively psychotic patients showed unique changes in REM and other sleep parameters, compared with control subjects. Further intensive and systematic case studies are, however, necessary to determine whether or not the reported sleep disturbances are an inherent feature of acute psychotic exacerbations. In the present work, we have therefore extended our previous studies in examining the sleep EEG concomitantly with the urinary catecholamines in three cases of periodic catatonia. Sleep patterns and all the three urinary catecholamines were studied longitudinally over several months, covering one to three periods in each patient.

Effect of topical hydrocortisone on the electrocorticogram of the cat.

Studies of the effect of corticotropin (ACTH) and adrenocortical hormones on the electrical activity of the brain are numerous. The effects of corticotropin, cortisone, and hydrocortisone are similar, and they are the reverse of those of desoxycorticosterone.* Cortisone decreases brain excitability in normal rats, as measured by electroshock seizure threshold and pentylenetetrazol (Metrazol) seizure threshold.† It counteracts the depressive action on brain excitability of desoxycorticosterone2in normal and adrenalectomized rats. In patients receiving cortisone and in subjects with normal EEG traces, it causes an increase of alpha frequency.4In adrenalectomized rats and patients with an abnormal EEG or Addison's disease, the slow EEG returns to normal under cortisone treatment.‡ Hydrocortisone administered intravenously increases theta activity in normal and epileptic subjects, with increase in bilateral spike-wave discharges.7The same abnormality has been observed in patients under cortisone treatment.8 The action of the hormones on brain excitability has

Electroencephalographic observations on patients undergoing cortisone and ACTH therapy.

THE influence of adrenocorticotropin and of cortisone on the brainwave pattern has been casually considered in many studies which have dealt with the clinical aspects and influence of these substances on various diseases for which they have been tried. In 1947 Grenell and McCrawley (1) reported an “increase in amplitude and some change in frequency of brain waves” after administration of adrenocortical extract to experimental animals and humans. Boland and Headley (2) elicited an increase in alpha frequency following cortisone administration. In 1949 Thorn (3) reported a decrease of slow activity and an increase of fast activity along with the general improvement of the electroencephalogram patterns when compound E was given to patients with Addison's disease. There are, however, very few detailed reports with serial electroencephalograms which deal with the effects of these hormones on the brainwave patterns, and the workers on the subject have come to different conclusions.