Spontaneous Alpha Research Articles

Enhanced Epileptic Seizure Detection through Wavelet-Based Analysis of EEG Signal Processing

Epilepsy affects millions worldwide, making timely seizure detection crucial for effective treatment and enhanced well-being. Electroencephalogram (EEG) analysis offers a non-intrusive solution, but its visual interpretation is prone to errors and requires a lot of time. Many existing works focus solely on achieving competitive levels of accuracy without considering processing speed or the computational complexity of their models. This study aimed to develop an automated technique for identifying epileptic seizures in EEG data through analysis methods. The efforts have been primarily focused on achieving high accuracy results by operating exclusively within a narrow frequency band of the signal, while also aiming to minimize computational complexity. In this article, a new automated approach is presented for seizure detection by combining signal processing and machine learning techniques. The proposed method comprises four stages: (1) Preprocessing: Savitzky–Golay filter to remove the background noise. (2) Decomposition: discrete wavelet transform (DWT) to extract spontaneous alpha and beta frequency bands. (3) Feature extraction: six features (mean, standard deviation, skewness, kurtosis, energy, and entropy) are computed for each frequency band. (4) Classification: a support vector machine (SVM) method classifies signals as normal or containing a seizure. The method was assessed using two publicly available EEG datasets. For the alpha band, the highest achieved accuracy was 92.82%, and for the beta band it was 90.55%, which demonstrates adequate capability in both bands for accurate seizure detection. Furthermore, the obtained low computational cost suggests a potentially valuable application in real-time assessment scenarios. The obtained results indicate its capacity as a valuable instrument for diagnosing epilepsy and monitoring patients. Further research is necessary for clinical validation and potential real-time deployment.

EEG resting state alpha dynamics predict an individual’s vulnerability to auditory hallucinations

AbstractTask-free brain activity exhibits spontaneous fluctuations between functional states, characterized by synchronized activation patterns in distributed resting-state (RS) brain networks. The temporal dynamics of the networks’ electrophysiological signatures reflect individual variations in brain activity and connectivity linked to mental states and cognitive functions and can predict or monitor vulnerability to develop psychiatric or neurological disorders. In particular, RS alpha fluctuations modulate perceptual sensitivity, attentional shifts, and cognitive control, and could therefore reflect a neural correlate of increased vulnerability to sensory distortions, including the proneness to hallucinatory experiences. We recorded 5 min of RS EEG from 33 non-clinical individuals varying in hallucination proneness (HP) to investigate links between task-free alpha dynamics and vulnerability to hallucinations. To this end, we used a dynamic brain state allocation method to identify five recurrent alpha states together with their spatiotemporal dynamics and most active brain areas through source reconstruction. The dynamical features of a state marked by activation in somatosensory, auditory, and posterior default-mode network areas predicted auditory and auditory-verbal HP, but not general HP, such that individuals with higher vulnerability to auditory hallucinations spent more time in this state. The temporal dynamics of spontaneous alpha activity might reflect individual differences in attention to internally generated sensory events and altered auditory perceptual sensitivity. Altered RS alpha dynamics could therefore instantiate a neural marker of increased vulnerability to auditory hallucinations.

Just a phase? Causal probing reveals spurious phasic dependence of sustained attention

For over a decade, electrophysiological studies have reported correlations between attention / perception and the phase of spontaneous brain oscillations. To date, these findings have been interpreted as evidence that the brain uses neural oscillations to sample and predict upcoming stimuli. Yet, evidence from simulations have shown that analysis artefacts could also lead to spurious pre-stimulus oscillations that appear to predict future brain responses. To address this discrepancy, we conducted an experiment in which visual stimuli were presented in time to specific phases of spontaneous alpha and theta oscillations. This allowed us to causally probe the role of ongoing neural activity in visual processing independent of the stimulus-evoked dynamics. Our findings did not support a causal link between spontaneous alpha / theta rhythms and behaviour. However, spurious correlations between theta phase and behaviour emerged offline using gold-standard time-frequency analyses. These findings are a reminder that care should be taken when inferring causal relationships between neural activity and behaviour using acausal analysis methods.

Frontal EEG alterations induced by hippocampal amyloid pathology in rats

PurposeIn this study, it was aimed to determine the dose-dependent effects of hippocampal amyloid beta (Aβ) on frontal EEG activity and to elucidate the possible non-invasive biomarkers by recording spontaneous EEG in free-moving rats. Material and methodsMale albino Wistar rats aged 3 months were randomly divided into 4 groups (n ​= ​8 for each group), obtained by intrahippocampal injection of saline or different doses of Aβ1-42 i.e. 0.01 ​μg/μl, 0.1 ​μg/μl, and 1 ​μg/μl. After two weeks of recovery period, spontaneous EEG recordings were obtained from frontal regions and spectral power analyses were performed. ResultsWe detected a general slowdown in the brain activity two weeks after Aβ1-42 injection.We observed significant increases in frontal alpha power (p ​= ​0.0021) and significant decreases in frontal beta power (p ​= ​0.0003) between the Sh and Aβ1-42-injected groups. More specifically, the ratio of the frontal EEG beta and alpha power (rFBA) was significantly affected by the intrahippocampal injection of Aβ1-42 (p ​< ​0.0001). Also, we observed that rFBA was negatively and strongly correlated with hippocampal Aβ1-42 peptide levels (r ​= ​−0.781, p ​< ​0.0001). ConclusionOur findings indicate that spontaneous frontal EEG beta and alpha activity were significantly affected by the intrahippocampal injection of Aβ1-42. However, the results suggest that the power ratios of these bands are more sensitive to the hippocampal amyloid pathology. As such, it is proposed that the rFBA may be a more effective biomarker for diagnosing hippocampal pathology induced by Aβ1-42.

Nanoscale evidence of zircon-coffinite-xenotime solid solution observed by atom probe tomography

Ion probe zircon U-Pb dating has been widely used in earth and planetary sciences research. Previous studies found that ion probes have problems in the U-Pb dating of zircon with high U content. When the U content of zircon reaches a high threshold, the apparent age of U-Pb will become scattered and mostly older, which is called the “high U effect”. Based on micron-scale observations, predecessors have proposed that the spontaneous alpha decay of high content of radioactive element U and its daughter nuclear recoil will damage the zircon lattice, resulting in an increased yield of Pb+ in SIMS analyses and therefore an older 206Pb/238U age. However, there are also studies showing that zircons that have not been damaged also show a “high U effect”. In this contribution, scanning electron microscopy, ion probe and atom probe tomography research were carried out on high U content zircon grains (3.0 ± 0.1 Ma) in a highly fractionated leucogranites from the Himalayas to study the microcosmic occurrence state of zirconium constituent elements. Results show that these zircon grains have extremely high U contents ranging from 4271 to 95,176 μg/g. The distribution of U, P and Y in zircon is inhomogeneous, with enrichment features in local nanoscale regions. Zr constituent elements mainly exist in two states: (1) lamellar enrichment region, which corresponds to the compositional oscillation ring of zircon. The lamellar high U region is nearly parallel distributed. Its composition is in the transition between zircon, coffinite (USiO4) and xenotime; (2) The agglomerated high U region, which appears as isolated particles in zircon with a composition close to coffinite. The composition of the observed highest U region is Zr2.7Si12.2O61.8U19.8P1.4Y1.2Yb0.6Hf0.3, and the particle size is ∼8 nm. Nanoscale coffinites and xenotimes in high U zircons result in obvious differences between the matrix with the ion probe zircon standard reference materials, which resulted in the “high U effect”.

Genetic association of apolipoprotein E genotype with EEG alpha rhythm and resting‐state functional MRI connectivity in non‐demented adults during aging

AbstractBackgroundThe ε4 allele of the apolipoprotein E (APOE) genotype is a major genetic risk factor for Alzheimer’s disease (AD), but the mechanisms underlying its influence are not completely understood. The study was aimed at determining the possible effect of APOE genotype on spontaneous EEG alpha rhythm characteristics and on the resting‐state functional MRI (fMRI) connectivity (rsFC) in large brain networks in non‐demented adults during aging.MethodWe examined individual alpha peak frequency (IAPF), the EEG alpha sub‐bands power and the fMRI rsFC in 137 non‐demented volunteers, age range 26‐79 years, stratified by APOE genotype. APOE ε3/ε3 subgroup (APOE4‐) included 91 subjects, APOE ε4/ε3+ (APOE4+) subgroup – 46 subjects. The individuals underwent resting‐state fMRI of the brain, the CONN Matlab/SPM‐based toolbox was used to study connectivity in brain networks (Whitfield‐Gabrieli and Nieto‐Castanon, 2012). Informed written consent was obtained from all participants. All subjects underwent a neurological examination and cognitive screening.ResultThe presence of the APOE4+ genotype was associated with lower IAPF and lower relative power of the 11‐13Hz alpha sub‐bands. The age‐related alpha rhythm slowing was more pronounced in the APOE4+ than in the APOE4+ non‐carriers. The negative rsFC between the left hippocampus and the right posterior parietal cortex was reduced for the APOE4+ carriers compared to the APOE4‐ carriers. EEG IAFT showed a significant inverse correlation between rsFC of the left hippocampus and the right posterior parietal cortex.ConclusionAPOE4+ genotype is associated with marked age‐related alpha rhythm slowing and the dysfunction of the inhibitory large‐scale hippocampal networks. Inhibitory deficit of these networks function, interconnected with alpha rhythm slowing, may be related to learning and memory impairments and contribute to the subsequent AD development.This study was supported by Russian Science Foundation (Project No. 19‐75‐30039, genotyping)

Improvement of Crystal Identification Accuracy for Depth-of-Interaction Detector System with Peak-to-Charge Discrimination Method

In positron emission tomography (PET), parallax errors degrade spatial resolution. The depth of interaction (DOI) information provides the position in the depth of the scintillator interacting with the γ-rays, thus reducing parallax errors. A previous study developed a Peak-to-Charge discrimination (PQD), which can separate spontaneous alpha decay in LaBr3:Ce. Since decay constant of GSO:Ce depends on Ce concentration, the PQD is expected to discriminate GSO:Ce scintillators with different Ce concentration. In this study, the PQD-based DOI detector system was developed, which can be processed online and implemented in PET. A detector was composed of four layers of GSO:Ce crystals and a PS-PMT. The four crystals were obtained from both the top and bottom of ingots with a nominal Ce concentration of 0.5 mol% and 1.5 mol%. The PQD was implemented on the Xilinx Zynq-7000 SoC board with 8ch Flash ADC to gain real-time processing, flexibility, and expandability. The results showed that the mean Figure of Merits in 1D between four scintillators are 1.5, 0.99, 0.91 for layers between 1st–2nd, 2nd–3rd, and 3rd–4th respectively, and the mean Error Rate in 1D between four scintillators are 3.50%, 2.96%, 13.3%, and 1.88% for layers 1, 2, 3, and 4, respectively. In addition, the introduction of the 2D PQDs resulted in the mean Figure of Merits in 2D greater than 0.9 and the mean Error Rate in 2D less than 3% in all layers.

The Electroencephalographic Brainwave Spectrum, Mindful Meditation, and Awareness: Hypothesis.

It is hypothesized that being mindfully aware is a spontaneous state of being. It is imbued with joy, peace and happiness. Such a state is periodically revealed during restful attentiveness or presence. It is also associated with spontaneous brain alpha activity of 8-13 Hz. In deep nonrapid eye movement sleep, there is synchronous delta activity at a coherent frequency of 0.1 Hz. Both of these brainwave ground states are spontaneous, calm and effortless. When any physical or mental effort is made, the alpha rhythm is desynchronized, and it is superposed by faster brain waves of beta (13-30 Hz) and gamma frequencies (30-150 Hz). This is associated with a stream of dualistic conscious experiences with contents. During deep sleep, delta activity is superposed by beta and gamma activity with microarousals resulting in dream experiences. During effortless, meditative awareness, the whole family of alpha rhythm is synchronized including (a) Occipital-parietal alpha with visual clarity, formless color, and the absence of visual imagery (b) Frontal eye-field alpha with relatively motionless eyes, and the absence of voluntary actions or plans to move the eyes in some direction, along with nonactive working memory, (c) Somatosensory alpha or Mu rhythm from the somatic motor-sensory cortex with the resultant stillness of the body including head, face, larynx, spine, hands and legs, (d) Mid-temporal auditory alpha with vocal quietness and internal verbal silence (Maunam) with a feeling of spontaneous silence and serenity, (e) Cingulate and precuneus alpha resulting in freedom from autobiographical memories and the sense of agency or ego. The insular cortex serves as a gatekeeper, a hierarchical controller to switch between conscious engagement or disengagement from the internal or the external world. It switches between the default mode network and the executive frontoparietal networks, between the sequential and the parallel modes of functioning. Mindful consciousness is local and dualistic, whereas mindful awareness is nonlocal and nondual.

Regular cannabis use modulates the impact of HIV on the neural dynamics serving cognitive control.

Cannabis use and HIV are independently associated with decrements in cognitive control. However, the combined effects of HIV and regular cannabis use on the brain circuitry serving higher-order cognition are unclear. Investigate the interaction between cannabis and HIV on neural interference effects during the flanker task and spontaneous activity in regions underlying higher-order cognition. The sample consisted of 100 participants, including people with HIV (PWH) who use cannabis, PWH who do not use cannabis, uninfected cannabis users, and uninfected nonusers. Participants underwent an interview regarding their substance use history and completed the Eriksen flanker task during magnetoencephalography (MEG). MEG data were imaged in the time-frequency domain and oscillatory maps depicting the neural flanker interference effect were probed for group differences. Voxel time series were then assessed for group-level differences in spontaneous activity. Group differences in behavioral performance were identified along with group differences in theta and alpha neural interference responses in higher-order regions across the cortex, with nonusers with HIV generally exhibiting the most aberrant responses. Likewise, time series analyses indicated that nonusers with HIV also had significantly elevated spontaneous alpha activity in the left inferior frontal and dorsolateral prefrontal cortices (dlPFC). Finally, we found that spontaneous and oscillatory alpha activity were significantly coupled in the inferior frontal cortex and dlPFC among cannabis users, but not nonusers. Regular cannabis use appears to suppress the impact of HIV on spontaneous and oscillatory alpha deficits in the left inferior frontal cortex and dlPFC.

Decoding violated sensory expectations from the auditory cortex of anaesthetised mice: Hierarchical recurrent neural network depicts separate 'danger' and 'safety' units.

The ability to respond appropriately to sensory information received from the external environment is among the most fundamental capabilities of central nervous systems. In the auditory domain, processes underlying this behaviour are studied by measuring auditory‐evoked electrophysiology during sequences of sounds with predetermined regularities. Identifying neural correlates of ensuing auditory novelty responses is supported by research in experimental animals. In the present study, we reanalysed epidural field potential recordings from the auditory cortex of anaesthetised mice during frequency and intensity oddball stimulation. Multivariate pattern analysis (MVPA) and hierarchical recurrent neural network (RNN) modelling were adopted to explore these data with greater resolution than previously considered using conventional methods. Time‐wise and generalised temporal decoding MVPA approaches revealed previously underestimated asymmetry between responses to sound‐level transitions in the intensity oddball paradigm, in contrast with tone frequency changes. After training, the cross‐validated RNN model architecture with four hidden layers produced output waveforms in response to simulated auditory inputs that were strongly correlated with grand‐average auditory‐evoked potential waveforms (r 2 > .9). Units in hidden layers were classified based on their temporal response properties and characterised using principal component analysis and sample entropy. These demonstrated spontaneous alpha rhythms, sound onset and offset responses and putative ‘safety’ and ‘danger’ units activated by relatively inconspicuous and salient changes in auditory inputs, respectively. The hypothesised existence of corresponding biological neural sources is naturally derived from this model. If proven, this could have significant implications for prevailing theories of auditory processing.

Modulation of magnetoencephalography alpha band activity by radiofrequency electromagnetic field depicted in sensor and source space

Several studies reported changes in spontaneous electroencephalogram alpha band activity related to radiofrequency electromagnetic fields, but findings showed both an increase and a decrease of its spectral power or no effect. Here, we studied the alpha band modulation after 900 MHz mobile phone radiofrequency exposure and localized cortical regions involved in these changes, via a magnetoencephalography (MEG) protocol with healthy volunteers in a double-blind, randomized, counterbalanced crossover design. MEG was recorded during eyes open and eyes closed resting-state before and after radiofrequency exposure. Potential confounding factors, known to affect alpha band activity, were assessed as control parameters to limit bias. Entire alpha band, lower and upper alpha sub-bands MEG power spectral densities were estimated in sensor and source space. Biochemistry assays for salivary biomarkers of stress (cortisol, chromogranin-A, alpha amylase), heart rate variability analysis and high-performance liquid chromatography for salivary caffeine concentration were realized. Results in sensor and source space showed a significant modulation of MEG alpha band activity after the radiofrequency exposure, with different involved cortical regions in relation to the eyes condition, probably because of different attention level with open or closed eyes. None of the control parameters reported a statistically significant difference between experimental sessions.

Alpha power is associated with hippocampal volume in Alzheimer’s disease: A combined MEG and MRI study

AbstractBackground New Therapeutics in Alzheimer’s Disease (NTAD) is a multi‐centre, longitudinal study to develop reliable and sensitive biomarkers for patients in the early stage of Mild Cognitive Impairment (MCI) and Alzheimer’s Disease (AD). The hallmark of E/MEG abnormalities in AD patients is changes to the power and frequency of the alpha rhythm. Here, we explore spontaneous alpha oscillations in the NTAD cohort and how they relate to diagnostic condition (patient vs control), resting task (eyes open vs eyes closed) and hippocampal atrophy.MethodAt present, there has been MRI and E/MEG data collected on neurologically healthy controls (N=15; MMSE M=29.4±0.74) and amyloid positive MCI and AD patients (N=46; MMSE M=24.8±3.37). Resting‐state E/MEG recordings were obtained for two 5‐minute sessions; eyes opened and eyes closed. Average power and peak frequency were computed for each participant. A T1‐weighted MR scan was used to calculate hippocampal volume, whilst accounting for individual brain volume. Firstly, we compared the average power and peak frequency for patients and controls in both the eyes opened and eyes closed conditions. Secondly, we explored how alpha varies across these conditions and diagnoses and how these differences relate to hippocampal volume.ResultWe found that patients had lower peak frequency and power compared to controls. Specifically, there was a decreased power in eyes closed, and decreased frequency in eyes opened. These differences were also present in hippocampal volume as patients had significantly smaller hippocampi than controls, and this was correlated with decreased alpha peak frequency specifically in the eyes opened session (R2 = 0.172). These individual differences were further associated with MMSE scores.ConclusionThere are individual differences between alpha frequency and power between patients and controls. Alpha decreases with increasing cognitive impairment and is related to hippocampal volume. Whilst this is specific to eyes opened or eyes closed, results suggest that progressive atrophy of the hippocampus is associated with decreased alpha frequency. This confirms the clinical benefit of E/MEG measurements in dementia research and improve our understanding of the integration between structural and electrophysiological measures of synaptic dysfunction. Ongoing data analysis will be conducted to standardise these measures for future clinical trials.

Effects of changes in end-tidal PO2 and PCO2 on neural responses during rest and sustained attention.

Impairments of cognitive function during alterations in arterial blood gases (e.g., high‐altitude hypoxia) may result from the disruption of neurovascular coupling; however, the link between changes in arterial blood gases, cognition, and cerebral blood flow (CBF) is poorly understood. To interrogate this link, we developed a multimodal empirical strategy capable of monitoring neural correlates of cognition and CBF simultaneously. Human participants performed a sustained attention task during hypoxia, hypercapnia, hypocapnia, and normoxia while electroencephalographic (EEG) activity and CBF (middle and posterior cerebral arteries; transcranial Doppler ultrasound) were simultaneously measured. The protocol alternated between rest and engaging in a visual target detection task that required participants to monitor a sequence of brief‐duration colored circles and detect infrequent, longer duration circles (targets). The target detection task was overlaid on a large, circular checkerboard that provided robust visual stimulation. Spectral decomposition and event‐related potential (ERP) analyses were applied to the EEG data to investigate spontaneous and task‐specific fluctuations in neural activity. There were three main sets of findings: (1) spontaneous alpha oscillatory activity was modulated as a function of arterial CO2 (hypocapnia and hypercapnia), (2) task‐related neurovascular coupling was disrupted by all arterial blood gas manipulations, and (3) changes in task‐related alpha and theta band activity and attenuation of the P3 ERP component amplitude were observed during hypocapnia. Since alpha and theta are linked with suppression of visual processing and executive control and P3 amplitude with task difficulty, these data suggest that transient arterial blood gas changes can modulate multiple stages of cognitive information processing.

Interoception Underlies Therapeutic Effects of Mindfulness Meditation for Posttraumatic Stress Disorder: A Randomized Clinical Trial

BackgroundMindfulness-based interventions have proven efficacy in treating posttraumatic stress disorder (PTSD), but the neurobiological mechanism underlying the therapeutic effects is unknown. As mindfulness meditation cultivates attention to the present moment and bodily sensations, neural functions related to interoception (i.e., central processes of bodily signals) might be such a mechanism. MethodsWe conducted a clinical trial in which veterans with PTSD were randomly assigned to receive an 8-week mindfulness-based stress reduction (MBSR) intervention (n = 47) or an active control intervention (present-centered group therapy; n = 51). We assessed pre- and postintervention PTSD symptoms and electroencephalography measures of neural outcomes, including spontaneous brain activity, cognitive task–related brain responses, and interoceptive brain responses (heartbeat-evoked brain responses). We conducted statistical causal mediation analyses using treatment type as a predictor, pre- and postintervention measures of symptom severity as treatment response, and the neural outcomes as mediators. ResultsCompared with the control group, the MBSR group had greater improvements in PTSD symptoms and increases in spontaneous alpha power (8–13 Hz), task-related frontal theta power (4–7 Hz in 140–220 ms after stimulus), and frontal theta heartbeat-evoked brain responses (3–5 Hz and 265–336 ms after R peak). The mediation analysis using latent difference score modeling revealed that only changes in frontal theta heartbeat-evoked brain responses mediated the MBSR treatment effect. ConclusionsMindfulness meditation improves brain functions of attentional control and resting brain states reflective of internally oriented relaxation. However, interoceptive neural functions enhanced by MBSR seem to be a primary cerebral mechanism that improves symptoms of PTSD.

Spontaneous double alpha decay: First experimental limit and prospects of investigation

Nuclear decays with simultaneous emission of two alpha particles are energetically possible for a number of nuclides. Prospects of searching for such kind of decay for nuclides present in the natural isotopic composition of elements are discussed here. The first experimental limit on half-life for 2α decay is set for 209Bi as T1/2 &gt; 2.9·1020 y at 90 % C.L., using the data of work [P. de Marcillac et al. Nature 422 (2003) 876]. Theoretical T1/2 estimations for the process are also given. Using these values, which are on the level of 1033 y or more, one can conclude that the prospects of experimental observation of 2α decay are very pessimistic.

The Effect of GSM Electromagnetic Field Exposure on the Waking Electroencephalogram: Methodological Influences.

Although there is consistent evidence that exposure to radiofrequency electromagnetic fields (RF-EMF) increases the spontaneous resting alpha spectral power of the electroencephalogram (EEG), the reliability of this evidence is uncertain as some studies have also failed to observe this effect. The present study aimed to determine whether the effect of RF-EMF exposure on EEG alpha power depends on whether EEG is derived from eyes open or closed conditions and assessed earlier (<5-min) versus later (>25-min) in the exposure interval. Thirty-six adults participated in three experimental sessions, each involving one exposure: "Sham," "Low," and "High" RF-EMF corresponding to peak spatial specific absorption rates averaged over 10 g of 0, 1, and 2 W/kg, respectively. Resting EEG was recorded at baseline (no exposure), during, and after exposure. Alpha power increase was found to be greater for the eyes open than eyes closed EEG during both the High (P = 0.04) and Low (P = 0.04) RF-EMF exposures. There was also a trend towardit being larger at the end, versus the start of the "High" 30-min exposure (P < 0.01; eyes open condition). This suggests that the use of eyes closed conditions, and insufficient RF-EMF exposure durations, are likely explanations for the failure of some studies to detect an RF-EMF exposure-related increase in alpha power, as such methodological choices decrease signal-to-noise ratios and increase type II error.

Spontaneous Alpha and Theta Oscillations Are Related to Complementary Aspects of Cognitive Control in Younger and Older Adults.

The resting-state human electroencephalogram (EEG) power spectrum is dominated by alpha (8–12 Hz) and theta (4–8 Hz) oscillations, and also includes non-oscillatory broadband activity inversely related to frequency (1/f activity). Gratton proposed that alpha and theta oscillations are both related to cognitive control function, though in a complementary manner. Alpha activity is hypothesized to facilitate the maintenance of representations, such as task sets in preparation for expected task conditions. In contrast, theta activity would facilitate changes in representations, such as the updating of task sets in response to unpredicted task demands. Therefore, theta should be related to reactive control (which may prompt changes in task representations), while alpha may be more relevant to proactive control (which implies the maintenance of current task representations). Less is known about the possible relationship between 1/f activity and cognitive control, which was analyzed here in an exploratory fashion. To investigate these hypothesized relationships, we recorded eyes-open and eyes-closed resting-state EEG from younger and older adults and subsequently tested their performance on a cued flanker task, expected to elicit both proactive and reactive control processes. Results showed that alpha power and 1/f offset were smaller in older than younger adults, whereas theta power did not show age-related reductions. Resting alpha power and 1/f offset were associated with proactive control processes, whereas theta power was related to reactive control as measured by the cued flanker task. All associations were present over and above the effect of age, suggesting that these resting-state EEG correlates could be indicative of trait-like individual differences in cognitive control performance, which may be already evident in younger adults, and are still similarly present in healthy older adults.

PET Imaging of Dopamine Neurotransmission During EEG Neurofeedback.

Neurofeedback (NFB) is a brain-based training method that enables users to control their own cortical oscillations using real-time feedback from the electroencephalogram (EEG). Importantly, no investigations to date have directly explored the potential impact of NFB on the brain’s key neuromodulatory systems. Our study’s objective was to assess the capacity of NFB to induce dopamine release as revealed by positron emission tomography (PET). Thirty-two healthy volunteers were randomized to either EEG-neurofeedback (NFB) or EEG-electromyography (EMG), and scanned while performing self-regulation during a single session of dynamic PET brain imaging using the high affinity D2/3 receptor radiotracer, [18F]Fallypride. NFB and EMG groups down-regulated cortical alpha power and facial muscle tone, respectively. Task-induced effects on endogenous dopamine release were estimated in the frontal cortex, anterior cingulate cortex, and thalamus, using the linearized simplified reference region model (LSRRM), which accounts for time-dependent changes in radiotracer binding following task initiation. Contrary to our hypothesis of a differential effect for NFB vs. EMG training, significant dopamine release was observed in both training groups in the frontal and anterior cingulate cortex, but not in thalamus. Interestingly, a significant negative correlation was observed between dopamine release in frontal cortex and pre-to-post NFB change in spontaneous alpha power, suggesting that intra-individual changes in brain state (i.e., alpha power) could partly result from changes in neuromodulatory tone. Overall, our findings constitute the first direct investigation of neurofeedback’s effect on the endogenous release of a key neuromodulator, demonstrating its feasibility and paving the way for future studies using this methodology.

Associations between sensory processing and electrophysiological and neurochemical measures in children with ASD: an EEG-MRS study

BackgroundAutism spectrum disorder (ASD) is associated with hyper- and/or hypo-sensitivity to sensory input. Spontaneous alpha power, which plays an important role in shaping responsivity to sensory information, is reduced across the lifespan in individuals with ASD. Furthermore, an excitatory/inhibitory imbalance has also been linked to sensory dysfunction in ASD and has been hypothesized to underlie atypical patterns of spontaneous brain activity. The present study examined whether resting-state alpha power differed in children with ASD as compared to TD children, and investigated the relationships between alpha levels, concentrations of excitatory and inhibitory neurotransmitters, and atypical sensory processing in ASD.MethodsParticipants included thirty-one children and adolescents with ASD and thirty-one age- and IQ-matched typically developing (TD) participants. Resting-state electroencephalography (EEG) was used to obtain measures of alpha power. A subset of participants (ASD = 16; TD = 16) also completed a magnetic resonance spectroscopy (MRS) protocol in order to measure concentrations of excitatory (glutamate + glutamine; Glx) and inhibitory (GABA) neurotransmitters.ResultsChildren with ASD evidenced significantly decreased resting alpha power compared to their TD peers. MRS estimates of GABA and Glx did not differ between groups with the exception of Glx in the temporal-parietal junction. Inter-individual differences in alpha power within the ASD group were not associated with region-specific concentrations of GABA or Glx, nor were they associated with sensory processing differences. However, atypically decreased Glx was associated with increased sensory impairment in children with ASD.ConclusionsAlthough we replicated prior reports of decreased alpha power in ASD, atypically reduced alpha was not related to neurochemical differences or sensory symptoms in ASD. Instead, reduced Glx in the temporal-parietal cortex was associated with greater hyper-sensitivity in ASD. Together, these findings may provide insight into the neural underpinnings of sensory processing differences present in ASD.

Vitamin D Prevents Pancreatic Cancer-Induced Apoptosis Signaling of Inflammatory Cells

Combined approaches based on immunotherapy and drugs supporting immune effector cell function might increase treatment options for pancreatic ductal adenocarcinoma (PDAC), vitamin D being a suitable drug candidate. In this study, we evaluated whether treatment with the vitamin D analogue, calcipotriol, counterbalances PDAC induced and SMAD4-associated intracellular calcium [Ca2+]i alterations, cytokines release, immune effector function, and the intracellular signaling of peripheral blood mononuclear cells (PBMCs). Calcipotriol counteracted the [Ca2+]i depletion of PBMCs induced by SMAD4-expressing PDAC cells, which conditioned media augmented the number of calcium flows while reducing whole [Ca2+]i. While calcipotriol inhibited spontaneous and PDAC-induced tumor necrosis factor alpha (TNF-α) release by PBMC and reduced intracellular transforming growth factor beta (TGF-β), it did not counteract the lymphocytes proliferation induced in allogenic co-culture by PDAC-conditioned PBMCs. Calcipotriol mainly antagonized PDAC-induced apoptosis and partially restored PDAC-inhibited NF-κB signaling pathway. In conclusion, alterations induced by PDAC cells in the [Ca2+]i of immune cells can be partially reverted by calcipotriol treatment, which promotes inflammation and antagonizes PBMCs apoptosis. These effects, together with the dampening of intracellular TGF-β, might result in an overall anti-tumor effect, thus supporting the administration of vitamin D in PDAC patients.