Changes In Alpha Activity Research Articles

Changes in EEG alpha-band power during prehension indicates neural motor drive inhibition.

Changes in alpha band activity (8-12 Hz) indicate the downregulation of brain regions during cognitive tasks, reflecting real-time cognitive load. Despite this, its feasibility to be used in a more dynamic environment with ongoing motor corrections has not been studied. This research used electroencephalography (EEG) to explore how different brain regions are engaged during a simple grasp and lift task where unexpected changes to the object's weight or surface friction are introduced. The results suggest that alpha activity changes related to motor error correction occur only in motor-related areas (i.e. central areas) but not in error processing areas (i.e., frontoparietal network) during unexpected weight changes. This suggests that oscillations over motor areas reflect the reduction of motor drive related to motor error correction, thus, being a potential cortical electrophysiological biomarker for the process and not solely as a proxy for cognitive demands. This observation is particularly relevant in scenarios where these signals are used to evaluate high cognitive demands co-occurring with high levels of motor errors and corrections, such as prosthesis use. The establishment of electrophysiological biomarkers of mental resource allocation during movement and cognition can help identify indicators of mental workload and motor drive, which may be useful for improving brain-machine interfaces.NEW & NOTEWORTHY We demonstrated that alpha suppression, an EEG phenomenon with high temporal resolution, occurs over the primary sensorimotor area during error correction during lift movements. Interpretations of alpha activity are often attributed to high cognitive demands, thus recognizing that it is also influenced by motor processes is important in situations where cognitive demands are paired with movement errors. This could further have application as a biomarker for error correction in human-machine interfaces, such as neuroprostheses.

Clinical manifestations and mechanisms of formation of neurological disorders in patients with vibration disease

The review presents an analysis of literature sources devoted to the study of changes in the nervous system in patients with vibration disease. Vibration-mediated cellular hypoxia, which occurs as a result of spastic changes in blood vessels, phase fluctuations in intravascular pressure, impaired blood and lymph outflow, causes suppression of energy metabolism, contributes to disorders at the level of receptor (glutamate, GABA-ergic, dopamine and cholinergic) and synaptic structures, conductors of pain and temperature sensitivity (demyelinization), analyzing neurons in the parietal region of the brain, regulatory proteins of the nervous tissue (NF-200, GFAP S-100). A low-amplitude, irregular, disorganized and sometimes deformed EEG spectrum with a predominance of the alpha wave and a shift of the alpha rhythm to the left reflects changes in the spontaneous electrical activity of brain structures in patients. With an increase in the experience dose of vibration-noise exposure, the dominant alpha activity changes to slow-wave or polyrhythmic. Mild and moderate diffuse changes in the brain become focal in nature, cortical-subcortical relationships are disrupted at the diencephalic level, creating a pathophysiological basis for sensorineural (sensory-neural) hearing loss, especially in patients with a genetic predisposition mediated by genes encoding proteins of the heat shock system. The psycho-emotional status of patients is characterized by a hypochondriacal focus on the state of health, mental disadaptation, psycho-emotional disorders in the form of anxiety, depressive mood. The analysis of literature sources on the mechanisms of the formation of neurological disorders in patients with vibration disease revealed the lack of data on the state of the multicomponent ghrelin system interacting with GHSR-1A and GHSR-1B receptors, which determines a new vector in further experimental and clinical studies.

Spatial attention is not affected by alpha or beta transcranial alternating current stimulation: A registered report

Using Electroencephalography (EEG) an event-related change in alpha activity has been observed over primary sensory cortices during the allocation of spatial attention. This is most prominent during top-down, or endogenous, attention, and nearly absent in bottom-up, or exogenous orienting. These changes are highly lateralised, such that an increase in alpha power is seen ipsilateral to the attended region of space and a decrease is seen contralaterally. Whether these changes in alpha oscillatory activity are causally related to attentional resources, or to perceptual processes, or are simply epiphenomenal, is unknown. If alpha oscillations are indicative of a causal mechanism whereby attention is allocated to a region of space, it remains an open question as to whether this is driven by ipsilateral increases or contralateral decreases in alpha power. This preregistered report set out to test these questions. To do so, we used transcranial Alternating Current Stimulation (tACS) to modulate alpha activity in the somatosensory cortex whilst measuring performance on established tactile attention paradigms. All participants completed an endogenous and exogenous tactile attention task in three stimulation conditions; alpha, sham and beta. Sham and beta stimulation operated as controls so that any observed effects could be attributed to alpha stimulation specifically. We replicated previous behavioural findings in all stimulation conditions showing a facilitation of cued trials in the endogenous task, and inhibition of return in the exogenous task. However, these were not affected by stimulation manipulations. Using Bayes-factor analysis we show strong support for the null hypotheses – that the manipulation of Alpha by tACS does not cause changes in tactile spatial attention. This well-powered study, conducted over three separate days, is an important contribution to the current debate regarding the efficiency of brain stimulation.

Systemic analysis of eeg activation response in right and left handers

Most researchers in the study of the EEG activation response studied changes in alpha activity, while the dynamics of changes in other EEG rhythms and functional interhemispheric asymmetry (FMAA) was described and analyzed to an immeasurably lesser extent. Considering electrogenesis as a systemic category, it is advisable to study the relationships between the amplitudes of EEG rhythms using multiple regression and correlation methods of analysis. The EEG was studied on practically healthy people, students, in the state of PR and OR. Lateralization (right-handed-left-handed) was determined by EEG parameters. Activation coefficients (AC) were determined by dividing the beta-2 rhythm duration index by the alpha rhythm duration index. Relationships formed between the amplitudes of EEG rhythms were studied using calculations of multiple linear regression and correlation.
 In own research we was show: when opening the eyes, the amplitude of alpha and beta-1 rhythms in right-handers and left-handers decreased statistically signifiantly. Changes in the parameters of beta-2 EEG rhythms when opening the eyes in right-handers were determined to be increased in the left and right hemispheres, and in left-handers only in the forehead-temporal abduction of the left hemisphere - an increase in the duration index. Indicators of theta rhythm in right-handed people decreased in the left and right hemispheres when opening the eyes, and in left-handers, changes in theta rhythm were manifested only in the crown-occiput abduction of the right abduction. The amplitude and frequency of the EEG delta rhythm in right-handers decreased in the left and right hemispheres, and the duration indices were determined to be statistically significantly increased in all leads, with the exception of the forehead-temporal of the left hemisphere, while in left-handers, changes in the delta rhythm were observed mainly in the right hemisphere and were expressed in a decrease in amplitudes and rhythm frequencies. In the study of FIA, the alpha-rhythm index of right-handers under PR conditions was determined to be negative, and in left-handers it was positive. Under conditions of operational rest, this indicator was positive for both left-handers and right-handers. When opening the eyes, the AC in most leads increased statistically significantly in both right-handers and left-handers.
 The regression analysis revealed that the number of statistically significant regression coefficients increased significantly in the left hemisphere in right-handers under OP conditions, while in left-handers it decreased in the right hemisphere.

Symptoms of depression together with trait anxiety increase the ability to predict alpha power change between attention and resting states

Research suggests that symptoms of anxiety may result in atypical alpha activity associated with cognitive functioning. It is well documented that symptoms of anxiety are often comorbid with symptoms of depression. However, the combined influence of these symptoms on alpha activity changes between engaged attention states and rest is poorly understood. We therefore aimed to investigate the specific added contribution depressive symptoms may have in predicting alpha power compared to anxiety alone. We measured the disparity in alpha power between a selective attention state compared to a resting state using EEG. Selective attention was engaged using the Eriksen flanker task. Our results show that alpha disparity was predicted significantly better when symptoms of depression were incorporated into the model, compared to trait anxiety alone. Also, both symptoms were significant predictors of alpha power change, but in opposite directions. Alpha disparity increased between rest and attention as trait anxiety symptoms increased, while disparity was negatively correlated with increased symptoms of depression. Clinical symptoms did not predict flanker task performance during incongruent trials, but did strongly relate to global executive dysfunction. Given that clinical symptoms were related to alpha change between attention and rest but not behavioral performance on the flanker task, it is possible that these neural patterns could reflect a compensatory strategy. These results further emphasize the importance of examining how the compounded influence symptoms of anxiety and depression manifest in executive abilities, and add to the growing body of evidence that there is a neurological differentiation between these disorders.

Two mechanisms facilitate regional independence between brain regions based on an examination of alpha-band activity in healthy control adult males

BackgroundAt rest, 8 to 12 Hz alpha rhythms are the dominant rhythm in the brain, with a common peak alpha frequency (PAF = the frequency at which alpha generators show maximum power) observed across brain regions. Although a common PAF across brain regions should result in high between-region connectivity, especially connectivity measures assessing the phase-similarity between alpha generators, high inter-regional alpha connectivity has not been observed. The present study was conducted as an initial step toward identifying mechanisms that allow brain regions to maintain functional independence in the presence of a common PAF. MethodsMEG data were obtained from 16 healthy control male adults (mean age = 24 years; range 21 to 30 years). A task requiring participants to alternate between a 10 s eyes-closed condition and a 5 s eyes-open condition was used to drive parietal-occipital alpha generators, with the 10 s eyes-closed condition eliciting large-amplitude alpha activity and thus providing alpha measures with good signal-to-noise ratio for source localization. Alpha source-space measures were obtained using Vector-based Spatial-Temporal Analysis using L1-minimum-norm. In each participant, the four strongest parietal-occipital alpha generators were identified. Connectivity between sources was assessed via a measure of phase-based connectivity called inter-site phase clustering (ISPC). ResultsIntra-class correlations (ICC) showed very high similarity in the average PAF (=computed using all eyes-closed data) between the four alpha sources (ICC single measure = 0.88, p < 0.001). Despite a common average PAF, across participants, significant ISPC was often observed no more than that expected by chance. Examination of the alpha time course data indicated that low ISPC was often due to instantaneous changes in alpha phase (phase slips). ISPC analyses removing data with phase slips indicated that low ISPC was also due to slight continuous changes in the alpha frequency, with frequency drift more likely in non-significant than significant ISPC trials. ConclusionsThe present exploratory effort suggested two processes underlying the lack of observed inter-regional alpha phase coherence that may help maintain regional functional independence even in the presence of a common PAF. In particular, although the alpha generators were observed to oscillate at the same rate on average, across time each alpha generator oscillated a little slower or faster, and about every one and a half seconds an alpha generator abruptly lost the beat. Because of this, functional independence among alpha generators (and thus brain regions) was the rule rather than the exception. Studies replicating these processes that allow brain regions to maintain functional independence, using different source localization methods and in different conditions (e.g., a true resting state), are warranted. Impact statementUsing source localization to measure parietal-occipital alpha generator activity, two properties that limit between-region alpha functional connectivity are proposed. In particular, a model of alpha generator activity is offered where via transient phase slips occurring approximately every 1.5 s, as well as slight non-stationarity in the alpha frequency, brain regions retain a common alpha frequency while also maintaining regional identity and presumably functionality. Findings also suggest novel markers for use in studies examining changes in alpha activity across maturation as well as in studies examining alpha activity in patient populations where alpha abnormalities have been reported.

Overground Walking Decreases Alpha Activity and Entrains Eye Movements in Humans.

Experiments in animal models have shown that running increases neuronal activity in early visual areas in light as well as in darkness. This suggests that visual processing is influenced by locomotion independent of visual input. Combining mobile electroencephalography, motion- and eye-tracking, we investigated the influence of overground free walking on cortical alpha activity (~10 Hz) and eye movements in healthy humans. Alpha activity has been considered a valuable marker of inhibition of sensory processing and shown to negatively correlate with neuronal firing rates. We found that walking led to a decrease in alpha activity over occipital cortex compared to standing. This decrease was present during walking in darkness as well as during light. Importantly, eye movements could not explain the change in alpha activity. Nevertheless, we found that walking and eye related movements were linked. While the blink rate increased with increasing walking speed independent of light or darkness, saccade rate was only significantly linked to walking speed in the light. Pupil size, on the other hand, was larger during darkness than during light, but only showed a modulation by walking in darkness. Analyzing the effect of walking with respect to the stride cycle, we further found that blinks and saccades preferentially occurred during the double support phase of walking. Alpha power, as shown previously, was lower during the swing phase than during the double support phase. We however could exclude the possibility that the alpha modulation was introduced by a walking movement induced change in electrode impedance. Overall, our work indicates that the human visual system is influenced by the current locomotion state of the body. This influence affects eye movement pattern as well as neuronal activity in sensory areas and might form part of an implicit strategy to optimally extract sensory information during locomotion.

Short-delay neurofeedback facilitates training of the parietal alpha rhythm

Objective. Feedback latency was shown to be a critical parameter in a range of applications that imply learning. The therapeutic effects of neurofeedback (NFB) remain controversial. We hypothesized that often encountered unreliable results of NFB intervention could be associated with large feedback latency values that are often uncontrolled and may preclude the efficient learning. Approach. We engaged our subjects into a parietal alpha power unpregulating paradigm facilitated by visual NFB based on the individually extracted envelope of the alpha-rhythm at P4 electrode. NFB was displayed either as soon as electroencephalographic (EEG) envelope was processed, or with an extra 250 or 500 ms delay. The feedback training consisted of 15 two-minute long blocks interleaved with 15 s pauses. We have also recorded 2 min long baselines immediately before and after the training. Main results. The time course of NFB-induced changes in the alpha rhythm power clearly depended on NFB latency, as shown with the adaptive Neyman test. NFB had a strong effect on the alpha-spindle incidence rate, but not on their duration or amplitude. The sustained changes in alpha activity measured after the completion of NFB training were negatively correlated to latency, with the maximum change for the shortest tested latency and no change for the longest. Significance. Here we for the first time show that visual NFB of parietal EEG alpha-activity is efficient only when delivered to human subjects at short latency, which guarantees that NFB arrives when an alpha spindle is still ongoing. Such a considerable effect of NFB latency on the alpha-activity temporal structure could explain some of the previous inconsistent results, where latency was neither controlled nor documented. Clinical practitioners and manufacturers of NFB equipment should add latency to their specifications while enabling latency monitoring and supporting short-latency operations.

The influence of mental fatigue on brain activity: Evidence from a systematic review with meta-analyses.

The occurrence of mental fatigue during tasks like driving a vehicle increases risk of injury or death. Changes in electroencephalographic (EEG) activity associated with mental fatigue has been frequently studied and considered a promising biomarker of mental fatigue. This is despite differences in methodologies and outcomes in prior research. A systematic review with meta-analyses was conducted to establish the influence of mental fatigue on EEG activity spectral bands, and to determine in which regions fatigue-related EEG spectral changes are likely to occur. A high-yield search strategy identified 21 studies meeting inclusion criteria for investigating the change in EEG spectral activity in non-diseased adults engaged in mentally fatiguing tasks. A medium effect size (using Cohen's g) of 0.68 (95%CI: 0.24-1.13) was found for increase in overall EEG activity following mental fatigue. Further examination of individual EEG spectral bands and regions using network meta-analyses indicated large increases in theta (g=1.03; 95%CI: 0.79-1.60) and alpha bands (g=0.85; 95%CI: 0.47-1.43), with small to moderate changes found in delta and beta bands. Central regions of the scalp showed largest change (g=0.80; 95%CI: 0.46-1.21). Sub-group analyses indicated large increases in theta activity in frontal, central and posterior sites (all g>1), with moderate changes in alpha activity in central and posterior sites. Findings have implications for fatigue monitoring and countermeasures with support for change in theta activity in frontal, central and posterior sites as a robust biomarker of mental fatigue and change in alpha wave activity considered a second line biomarker to account for individual variability.

Alpha-band Activity Tracks the Zoom Lens of Attention.

Voluntary control over spatial attention has been likened to the operation of a zoom lens, such that processing quality declines as the size of the attended region increases, with a gradient of performance that peaks at the center of the selected area. Although concurrent changes in activity in visual regions suggest that zoom lens adjustments influence perceptual stages of processing, extant work has not distinguished between changes in the spatial selectivity of attention-driven neural activity and baseline shift of activity that can increase mean levels of activity without changes in selectivity. Here, we distinguished between these alternatives by measuring EEG activity in humans to track preparatory changes in alpha activity that indexed the precise topography of attention across the possible target positions. We observed increased spatial selectivity in alpha activity when observers voluntarily directed attention toward a narrower region of space, a pattern that was mirrored in target discrimination accuracy. Thus, alpha activity tracks both the centroid and spatial extent of covert spatial attention before the onset of the target display, lending support to the hypothesis that narrowing the zoom lens of attention shapes the initial encoding of sensory information.

The pedunculopontine region and breathing in Parkinson's disease.

ObjectiveRespiratory abnormalities such as upper airway obstruction are common in Parkinson's disease (PD) and are an important cause of mortality and morbidity. We tested the effect of pedunculopontine region (PPNr) stimulation on respiratory maneuvers in human participants with PD, and separately recorded PPNr neural activity reflected in the local field potential (LFP) during these maneuvers.MethodsNine patients with deep brain stimulation electrodes in PPNr, and seven in globus pallidus interna (GPi) were studied during trials of maximal inspiration followed by forced expiration with stimulation OFF and ON. Local field potentials (LFPs) were recorded in the unstimulated condition.Results PEFR increased from 6.41 ± 0.63 L/sec in the OFF stimulation state to 7.5 L ± 0.65 L/sec in the ON stimulation state (z = −2.666, df = 8, P = 0.024). Percentage improvement in PEFR was strongly correlated with proximity of the stimulated electrode contact to the mesencephalic locomotor region in the rostral PPN (r = 0.814, n = 9, P = 0.008). Mean PPNr LFP power increased within the alpha band (7–11 Hz) during forced respiratory maneuvers (1.63 ± 0.16 μV2/Hz) compared to resting breathing (0.77 ± 0.16 μV2/Hz; z = −2.197, df = 6, P = 0.028). No changes in alpha activity or spirometric indices were seen with GPi recording or stimulation. Percentage improvement in PEFR was strongly positively correlated with increase in alpha power (r = 0.653, n = 14 (7 PPNr patients recorded bilaterally), P = 0.0096).Interpretation PPNr stimulation in PD improves indices of upper airway function. Increased alpha‐band activity is seen within the PPNr during forced respiratory maneuvers. Our findings suggest a link between the PPNr and respiratory performance in PD.

EEG alpha activity is moderated by the serial order effect during divergent thinking

Prior work has demonstrated that the serial order effect is commonly observed during the Alternative Uses Task, where generated uses become more creative over time while fluency decreases. Yet the neural correlates of the serial order effect are still relatively unexplored. The present study aimed to investigate the electrophysiological correlates underlying this effect. EEG alpha activity was measured using a task-related power paradigm while participants completed both the Alternative Uses Task as well as a Category Fluency Task. The results indicated that left hemisphere alpha power increased relative to right alpha power as a function of the serial order effect in the Alternative Uses Task, but not in the Category Fluency Task. This finding provides evidence that the pattern of observed EEG alpha activity changes over the course of the serial order effect.

Unsuccessful reduction of high-frequency alpha activity during cognitive activation in schizophrenia.

Electroencephalogram (EEG) alpha activity during resting state reflects the 'readiness' of an individual to respond to the environment; this includes the performance of cognitive processes. Alpha activity is reported to be attenuated in schizophrenia (SCZ). Understanding the interaction between alpha activity during rest and when cognitively engaged may provide insights into the neural circuitry, which is dysfunctional in SCZ. This study investigated the changes of alpha activity between resting state and cognitive engagement in SCZ patients. Thirty-four SCZ patients and 29 healthy controls (HC) were recruited. EEG was performed in the resting state and during an auditory P300 task. All experimental procedures followed the relevant institutional guidelines and regulations. In SCZ, high-frequency alpha activity was reduced in the resting state. High-frequency alpha source density was decreased in both the resting-state and a P300 task condition in patients, compared to HC. HC, but not SCZ patients, showed a reduction in high-frequency alpha source density during the P300 task compared to the resting state. The negative correlation between high-frequency alpha source density in the resting state and positive symptoms was significant. High-frequency alpha activity in SCZ patients and its unsuccessful reduction during cognitive processing may be biological markers of SCZ.

Brain dynamics during the sleep onset transition: An EEG source localization study

EEG source localization is an essential tool to reveal the cortical sources underlying brain oscillatory activity. We applied LORETA, a technique of EEG source localization, to identify the principal brain areas involved in the process of falling asleep (sleep onset, SO). We localized the contributing brain areas of activity in the classical frequency bands and tracked their temporal evolution (in 2-min intervals from 2 min prior to SO up to 10 min after SO) during a baseline night and subsequent recovery sleep after total sleep deprivation of 40 h.Delta activity (0.5–5 Hz) gradually increased both in baseline and recovery sleep, starting in frontal areas and finally involving the entire cortex. This increase was steeper in the recovery condition. The evolution of sigma activity (12–16 Hz) resembled an inverted U-shape in both conditions and the activity was most salient in the parietal cortex. In recovery, sigma activity reached its maximum faster than in baseline, but attained lower levels. Theta activity (5–8 Hz) increased with time in large parts of the occipital lobe (baseline and recovery) and in recovery involved additionally frontal areas. Changes in alpha activity (8–12 Hz) at sleep onset involved large areas of the cortex, whereas activity in the beta range (16–24 Hz) was restricted to small cortical areas. The dynamics in recovery could be considered as a “fast-forward version” of the one in baseline.Our results confirm that the process of falling asleep is neither spatially nor temporally a uniform process and that different brain areas might be falling asleep at a different speed potentially reflecting use dependent aspects of sleep regulation.

Changes in alpha activity reveal that social opinion modulates attention allocation during face processing

Participants' performance differs when conducting a task in the presence of a secondary individual, moreover the opinion the participant has of this individual also plays a role. Using EEG, we investigated how previous interactions with, and evaluations of, an avatar in virtual reality subsequently influenced attentional allocation to the face of that avatar. We focused on changes in the alpha activity as an index of attentional allocation. We found that the onset of an avatar's face whom the participant had developed a rapport with induced greater alpha suppression. This suggests greater attentional resources are allocated to the interacted-with avatars. The evaluative ratings of the avatar induced a U-shaped change in alpha suppression, such that participants paid most attention when the avatar was rated as average. These results suggest that attentional allocation is an important element of how behaviour is altered in the presence of a secondary individual and is modulated by our opinion of that individual.

Effect of distress on transient network dynamics and topological equilibrium in phantom sound perception

Distress is a domain-general behavioral symptom whose neural correlates have been under investigation for a long time now. Although some studies suggest that distress is encoded by changes in alpha activity and functional connectivity between specific brain regions, no study that we know has delved into the whole brain temporal dynamics of the distress component. In the current study, we compare the changes in the mean and variance of functional connectivity and small-worldness parameter over 3 min of resting state EEG to analyze the fluctuation in transient stable states, and network structure. On comparing these measures between healthy controls and patients experiencing low and high levels of distress due to a continuous ringing in the ear (tinnitus), we observe an increase in fluctuation between transient stable states characterized by an increase in both variance of functional connectivity and the small-worldness parameter. This results in a possible increase in degrees of freedom leading to a paradoxical equilibrium of the network structure in highly distressed patients. This may also be interpreted as a maladaptive compensation to look for information in order to reduce the hyper-salience in highly distressed individuals. In addition, this is correlated with the amount of distress only in the high distress tinnitus group, suggesting a catastrophic breakdown of the brain's resilience. Distress not only accompanies tinnitus, but other disorders such as somatic disorders, fibromyalgia, post-traumatic stress disorder, etc. Since the current study focuses on a disorder-general distress symptom, the methods and results of the current study have a wide application in different neuropathologies.

Cortical Alpha Oscillations Predict Speech Intelligibility.

Understanding speech in noise (SiN) is a complex task involving sensory encoding and cognitive resources including working memory and attention. Previous work has shown that brain oscillations, particularly alpha rhythms (8–12 Hz) play important roles in sensory processes involving working memory and attention. However, no previous study has examined brain oscillations during performance of a continuous speech perception test. The aim of this study was to measure cortical alpha during attentive listening in a commonly used SiN task (digits-in-noise, DiN) to better understand the neural processes associated with “top-down” cognitive processing in adverse listening environments. We recruited 14 normal hearing (NH) young adults. DiN speech reception threshold (SRT) was measured in an initial behavioral experiment. EEG activity was then collected: (i) while performing the DiN near SRT; and (ii) while attending to a silent, close-caption video during presentation of identical digit stimuli that the participant was instructed to ignore. Three main results were obtained: (1) during attentive (“active”) listening to the DiN, a number of distinct neural oscillations were observed (mainly alpha with some beta; 15–30 Hz). No oscillations were observed during attention to the video (“passive” listening); (2) overall, alpha event-related synchronization (ERS) of central/parietal sources were observed during active listening when data were grand averaged across all participants. In some participants, a smaller magnitude alpha event-related desynchronization (ERD), originating in temporal regions, was observed; and (3) when individual EEG trials were sorted according to correct and incorrect digit identification, the temporal alpha ERD was consistently greater on correctly identified trials. No such consistency was observed with the central/parietal alpha ERS. These data demonstrate that changes in alpha activity are specific to listening conditions. To our knowledge, this is the first report that shows almost no brain oscillatory changes during a passive task compared to an active task in any sensory modality. Temporal alpha ERD was related to correct digit identification.

Neural mechanisms of rhythm-based temporal prediction: Delta phase-locking reflects temporal predictability but not rhythmic entrainment.

Predicting the timing of upcoming events enables efficient resource allocation and action preparation. Rhythmic streams, such as music, speech, and biological motion, constitute a pervasive source for temporal predictions. Widely accepted entrainment theories postulate that rhythm-based predictions are mediated by synchronizing low-frequency neural oscillations to the rhythm, as indicated by increased phase concentration (PC) of low-frequency neural activity for rhythmic compared to random streams. However, we show here that PC enhancement in scalp recordings is not specific to rhythms but is observed to the same extent in less periodic streams if they enable memory-based prediction. This is inconsistent with the predictions of a computational entrainment model of stronger PC for rhythmic streams. Anticipatory change in alpha activity and facilitation of electroencephalogram (EEG) manifestations of response selection are also comparable between rhythm- and memory-based predictions. However, rhythmic sequences uniquely result in obligatory depression of preparation-related premotor brain activity when an on-beat event is omitted, even when it is strategically beneficial to maintain preparation, leading to larger behavioral costs for violation of prediction. Thus, while our findings undermine the validity of PC as a sign of rhythmic entrainment, they constitute the first electrophysiological dissociation, to our knowledge, between mechanisms of rhythmic predictions and of memory-based predictions: the former obligatorily lead to resonance-like preparation patterns (that are in line with entrainment), while the latter allow flexible resource allocation in time regardless of periodicity in the input. Taken together, they delineate the neural mechanisms of three distinct modes of preparation: continuous vigilance, interval-timing-based prediction and rhythm-based prediction.

Expectation of nocebo hyperalgesia affects EEG alpha-activity

Changes in EEG activity have been related to clinical and experimental pain. Expectation of a negative outcome can lead to pain enhancement (nocebo hyperalgesia) and can alter the response to therapeutic interventions. The present study characterizes EEG alteration related to pain facilitation by nocebo. Thirty healthy subjects were randomly assigned to the nocebo or control group. Five-minute EEG was recorded under: resting state, tonic innocuous heat and tonic noxious heat before and after the application of a sham inert cream to the non-dominant volar forearm combined with cognitive manipulation. The intensity and unpleasantness of heat-induced pain increased after cognitive manipulation in the nocebo group compared to control and was associated with enhanced low alpha (8–10Hz) activity. However, changes in alpha activity were predicted by catastrophizing but not by pain intensity or unpleasantness, which suggest that low alpha power might reflect brain activity related to negative cognitive–affective responses to pain.

FEATURES OF THE ALPHA ACTIVITY OF THE BRAIN ON THE BACKGROUND OF MEDITATIVEPSYCHOLOGICAL TRAINING

The aim of the study was to identify the characteristics of the alpha activity of the brain on the background of meditative psychological training, depending on experience and qualifications. Materials and methods. Examined 30 volunteers of 25-45 years old, 12 men and 18 women. Depending on the experience of meditative practices, the participants were divided into three groups: a group with no experience of meditation (beginners), group practicing Kundalini yoga in General classes (1-3 times a week) – average level, and a group of professionals (yoga teachers, practicing for at least three years and having a daily practice). All participants did not had neurological and psychiatric diseases, and had no dependence on alcohol or drugs and was relatively healthy. A study was conducted of the electrical activity of the brain at rest, during and after the meditative psychological training. As a result we acquired data for the frontal, Central, occipital and temporal leads. Results. Identified a number of changes of EEG parameters in the application of meditation techniques, which depended on the experience and qualifications of the subjects. Changes of alpha activity occur in all areas of the brain with the development of meditation techniques, whereas newcomers have changes mainly in the frontal region. The index of alpha-rhythm at rest is higher in groups with experience of meditation practice. The given material allows to recommend psychological training (meditation techniques of Kundalini yoga) to reduce the level of fatigue and correction of psycho-emotional excitation.