Low-Cost Classroom and Laboratory Exercises for Investigating Both Wave and Event-Related Electroencephalogram Potentials.

Electroencephalography (EEG) has given rise to a myriad of new discoveries over the last 90 years. EEG is a noninvasive technique that has revealed insights into the spatial and temporal processing of brain activity over many neuroscience disciplines, including sensory, motor, sleep, and memory formation. Most undergraduate students, however, lack laboratory access to EEG recording equipment or the skills to perform an experiment independently. Here, we provide easy-to-follow instructions to measure both wave and event-related EEG potentials using a portable, low-cost amplifier (Backyard Brains, Ann Arbor, MI) that connects to smartphones and PCs, independent of their operating system. Using open-source software (SpikeRecorder) and analysis tools (Python, Google Colaboratory), we demonstrate tractable and robust laboratory exercises for students to gain insights into the scientific method and discover multidisciplinary neuroscience research. We developed 2 laboratory exercises and ran them on participants within our research lab (N = 17, development group). In our first protocol, we analyzed power differences in the alpha band (8-13 Hz) when participants alternated between eyes open and eyes closed states (n = 137 transitions). We could robustly see an increase of over 50% in 59 (43%) of our sessions, suggesting this would make a reliable introductory experiment. Next, we describe an exercise that uses a SpikerBox to evoke an event-related potential (ERP) during an auditory oddball task. This experiment measures the average EEG potential elicited during an auditory presentation of either a highly predictable ("standard") or low-probability ("oddball") tone. Across all sessions in the development group (n=81), we found that 64% (n=52) showed a significant peak in the standard response window for P300 with an average peak latency of 442ms. Finally, we tested the auditory oddball task in a university classroom setting. In 66% of the sessions (n=30), a clear P300 was shown, and these signals were significantly above chance when compared to a Monte Carlo simulation. These laboratory exercises cover the two methods of analysis (frequency power and ERP), which are routinely used in neurology diagnostics, brain-machine interfaces, and neurofeedback therapy. Arming students with these methods and analysis techniques will enable them to investigate this laboratory exercise's variants or test their own hypotheses.

Is frontal EEG gamma power a neural correlate of language in toddlerhood? An examination of late talking and expressive language ability.

Few studies have examined neural correlates of late talking in toddlers, which could aid in understanding etiology and improving diagnosis of developmental language disorder (DLD). Greater frontal gamma activity has been linked to better language skills, but findings vary by risk for developmental disorders, and this has not been investigated in late talkers. This study examined whether frontal gamma power (30-50 Hz), from baseline-state electroencephalography (EEG), was related to DLD risk (categorical late talking status) and a continuous measure of expressive language in n = 124 toddlers. Frontal gamma power was significantly associated with late talker status when controlling for demographic factors and concurrent receptive language (ß = 1.96, McFadden's Pseudo R2 = 0.21). Demographic factors and receptive language did not significantly moderate the association between frontal gamma power and late talker status. A continuous measure of expressive language ability was not significantly associated with gamma (r = -0.07). Findings suggest that frontal gamma power may be useful in discriminating between groups of children that differ in DLD risk, but not for expressive language along a continuous spectrum of ability.

Peculiarities in Rabi oscillations for fast-relaxing electron spins.

Rabi oscillations (transient nutations) are a phenomenon that has proven itself well in EPR for identifying electron spin quantum numbers and electron-spin transitions. They are successfully applied when the Rabi frequency significantly exceeds the spin relaxation rates and therefore does not depend on these rates. However, the short transverse relaxation time, being comparable to or even shorter than the dead time of EPR spectrometers, makes it difficult to observe Rabi oscillations and their frequency depends not only on the intensity of the short microwave pulse, but also on its shape and relaxation rates. Two techniques are considered that are suitable for this case, in which Rabi oscillations are detected by monitoring the FID amplitude as a function of pulse duration or microwave field amplitude. We describe the FID-detected Rabi oscillations analytically or numerically for rectangular or shaped pulses, respectively. The description is confirmed by EPR experiments using DPPH as a model sample.

Emerging Functions of Neuromodulation during Sleep.

Neuromodulators act on multiple timescales to affect neuronal activity and behavior. They function as synaptic fine-tuners and master coordinators of neuronal activity across distant brain regions and body organs. While much research on neuromodulation has focused on roles in promoting features of wakefulness and transitions between sleep and wake states, the precise dynamics and functions of neuromodulatory signaling during sleep have received less attention. This review discusses research presented at our minisymposium at the 2024 Society for Neuroscience meeting, highlighting how norepinephrine, dopamine, and acetylcholine orchestrate brain oscillatory activity, control sleep architecture and microarchitecture, regulate responsiveness to sensory stimuli, and facilitate memory consolidation. The potential of each neuromodulator to influence neuronal activity is shaped by the state of the synaptic milieu, which in turn is influenced by the organismal or systemic state. Investigating the effects of neuromodulator release across different sleep substates and synaptic environments offers unique opportunities to deepen our understanding of neuromodulation and explore the distinct computational opportunities that arise during sleep. Moreover, since alterations in neuromodulatory signaling and sleep are implicated in various neuropsychiatric disorders and because existing pharmacological treatments affect neuromodulatory signaling, gaining a deeper understanding of the less-studied aspects of neuromodulators during sleep is of high importance.

Challenges and Approaches in the Study of Neural Entrainment.

When exposed to rhythmic stimulation, the human brain displays rhythmic activity across sensory modalities and regions. Given the ubiquity of this phenomenon, how sensory rhythms are transformed into neural rhythms remains surprisingly inconclusive. An influential model posits that endogenous oscillations entrain to external rhythms, thereby encoding environmental dynamics and shaping perception. However, research on neural entrainment faces multiple challenges, from ambiguous definitions to methodological difficulties when endogenous oscillations need to be identified and disentangled from other stimulus-related mechanisms that can lead to similar phase-locked responses. Yet, recent years have seen novel approaches to overcome these challenges, including computational modeling, insights from dynamical systems theory, sophisticated stimulus designs, and study of neuropsychological impairments. This review outlines key challenges in neural entrainment research, delineates state-of-the-art approaches, and integrates findings from human and animal neurophysiology to provide a broad perspective on the usefulness, validity, and constraints of oscillatory models in brain-environment interaction.

Microcirculatory Dysfunction in Patients With Diabetes Mellitus Detected by a Distributed System of Wearable Laser Doppler Flowmetry Analysers.

The paper is devoted to the study of perfusion and amplitude-frequency spectra of laser Doppler flowmetry (LDF) signals in patients with diabetes mellitus (DM) in different skin areas of the upper and lower extremities using a distributed system of wearable LDF analysers. LDF measurements were performed in the areas of the fingers, toes, wrists and shins. The mean perfusion values, the amplitudes of blood flow oscillations in endothelial, neurogenic, myogenic, respiratory and cardiac frequency ranges, and the values of nutritive blood flow were analysed. The results revealed a decrease in tissue perfusion and nutritive blood flow in the lower extremities and an increase in these parameters in the upper extremities in patients with DM. A decrease in the amplitudes of endothelial and neurogenic oscillations was observed. The obtained results confirm the possibility of using wearable LDF analysers to detect differences in the blood flow regulation in normal and pathological conditions.

Effects of acute and chronic ketamine administration on spontaneous and evoked brain activity.

Schizophrenia is believed to be, at least in part, a dysfunction of the glutamatergic system. In line with anatomical evidence, suppressing N-methyl-D-aspartate (NMDA) neurotransmission leads to symptoms that are characteristic of schizophrenia. Rodent models of schizophrenia often involve the acute application of NMDA antagonists, which produce both behavioural and brain activity changes that closely resemble symptoms observed in schizophrenia. It is, however, important to note that the full spectrum of schizophrenia symptoms may not be manifested following the acute suppression of NMDA receptors. This has led to the proposal of a chronic model where NMDA receptors are suppressed for prolonged periods. Although the chronic model has shown promising results from a behavioural perspective and alterations in metabolic processes in the brain, its impact on brain oscillations remains largely unknown. The aim of this study is to examine the impact of acute and chronic NMDA neurotransmission suppression on brains' oscillatory activity. To achieve this, chronic brain activity recordings in mice of both sexes were used to assess both spontaneous and evoked brain oscillations. The study demonstrates that an acute suppression of NMDA receptors alters brain oscillations across a wide frequency spectrum and diminishes the oscillatory potency in evoked responses, paralleling changes observed in schizophrenia. However, the chronic suppression of NMDA receptors did not have the expected cumulative effect on brain activity. This research highlights the robust yet similar impacts of acute and chronic NMDA receptor suppression on brain activity, contributing to the nuanced understanding of rodent models of schizophrenia.

Computational Model of Complex Calcium Dynamics: Store Operated Ca2+ Channels and Mitochondrial Associated Membranes in Pancreatic Acinar Cells.

This proposed model explores the intricate Ca2+ dynamics within the pancreatic acinar cells (PACs) by emphasizing the role of store-operated Ca2+ entry (SOCE) and the mitochondrial-associated membranes (MAMs) in the secretory region (apical) of the PACs. Traditionally, Ca2+ releases from the endoplasmic reticulum (ER) via calcium-induced calcium release (CICR). It has been shown to be important in regulating functions such as secretion of digestive enzymes in PACs. However, this model posits that upon the depletion of Ca2+ in the ER, the signaling protein stromal interaction molecule (STIM1) is activated. Activated STIM1, then facilitates the opening of Orai channels, allowing Ca2+ influx through the store-operated calcium channels (SOCCs). The model highlights the complexity of the Ca2+ dynamics, and the importance of SOCE and MAMs in the PACs Ca2+ homeostasis. The numerical and bifurcation analysis illustrate how changes in agonist concentrations can lead to the diverse Ca2+ oscillation patterns, such as thin to broader oscillations, sinusoidal patterns, and baseline fluctuations, driven by the feedback mechanisms involving Ca2+ and inositol 1,4,5 trisphosphate (IP3). This understanding could have broader implications for cellular physiology and the development of therapies targeting Ca2+ signaling pathways.

NMDA receptor antagonist high-frequency oscillations are transmitted via bottom-up feedforward processing.

In mammals, NMDA receptor antagonists have been linked to the emergence of high-frequency oscillations (HFO, 130-180 Hz) in cortical and subcortical brain regions. The extent to which transmission of this rhythm is dependent on feedforward (bottom-up) or feedback (top-down) mechanisms is unclear. Previously, we have shown that the olfactory bulb (OB), known to orchestrate oscillations in many brain regions, is an important node in the NMDA receptor-dependent HFO network. Since the piriform cortex (PC) receives major input from the OB, and can modulate OB activity via feedback projections, it represents an ideal site to investigate transmission modalities. Here we show, using silicon probes, that NMDA receptor antagonist HFO are present in the PC associated with current dipoles, although of lower power than the OB. Granger causality and peak-lag analyses implicated the OB as the driver of HFO in the PC. Consistent with this, reversible inhibition of the OB resulted in a reduction of HFO power both locally and in the PC. In contrast, inhibition of the PC had minimal impact on OB activity. Collectively, these findings point to bottom-up mechanisms in mediating the transmission of NMDA receptor antagonist-HFO, at least in olfactory circuits.

Calcium oscillations and mitochondrial enzymes in stem cells.

Calcium oscillations are rhythmic fluctuations of the intracellular concentration of calcium ions (Ca2+). As Ca2+ evokes various cellular processes, its intracellular concentration is tightly regulated. Ca2+ oscillations control biological events, including neuronal differentiation and proliferation of mesenchymal stem cells. The frequency and pattern of Ca2+ oscillations depend on cell type. Researchers have studied Ca2+ oscillations to better understand how cells communicate and regulate physiological processes. Dysregulation of Ca2+ oscillations causes health problems, such as neurodegenerative disorders. This review discusses the potential functions of Ca2+ oscillations in stem cells.

Neuronal oscillations in cognition: Down syndrome as a model of mouse to human translation.

Down syndrome (DS), a prevalent cognitive disorder resulting from trisomy of human chromosome 21 (Hsa21), poses a significant global health concern. Affecting approximately 1 in 800 live births worldwide, DS is the leading genetic cause of intellectual disability and a major predisposing factor for early-onset Alzheimer's dementia. The estimated global population of individuals with DS is 6 million, with increasing prevalence due to advances in DS health care. Global efforts are dedicated to unraveling the mechanisms behind the varied clinical outcomes in DS. Recent studies on DS mouse models reveal disrupted neuronal circuits, providing insights into DS pathologies. Yet, translating these findings to humans faces challenges due to limited systematic electrophysiological analyses directly comparing human and mouse. Additionally, disparities in experimental procedures between the two species pose hurdles to successful translation. This review provides a concise overview of neuronal oscillations in human and rodent cognition. Focusing on recent DS mouse model studies, we highlight disruptions in associated brain function. We discuss various electrophysiological paradigms and suggest avenues for exploring molecular dysfunctions contributing to DS-related cognitive impairments. Deciphering neuronal oscillation intricacies holds promise for targeted therapies to alleviate cognitive disabilities in DS individuals.

Adolescent vaping behaviours: Exploring the dynamics of a social contagion model.

Vaping, or the use of electronic cigarettes (e-cigarettes), is an ongoing issue for public health. The rapid increase in e-cigarette usage, particularly among adolescents, has often been referred to as an epidemic. Drawing upon this epidemiological analogy between vaping and infectious diseases as a theoretical framework, we present a deterministic compartmental model of adolescent e-cigarette smoking which accounts for social influences on initiation, relapse, and cessation behaviours. We use results from a sensitivity analysis of the model's parameters on various response variables to identify key influences on system dynamics and simplify the model into one that can be analysed more thoroughly. We identify a single feasible endemic equilibrium for the proportion of smokers that decreases as social influence on cessation increases. Through steady state and stability analyses, as well as simulations of the model, we conclude that social influences from and on temporary quitters are not important in overall model dynamics, and that social influences from permanent quitters can have a significant impact on long-term system dynamics. In particular, we show that social influence on cessation can induce persistent recurrent smoking outbreaks.

Microglial morphology aligns with vigilance stage-specific neuronal oscillations in a brain region-dependent manner.

Microglia, the resident immune cells in the brain, dynamically adapt their morphology based on their functional state. This study explored the relationship between microglial morphology and sleep-wake cycles in mice. Using Iba1 immunostaining to identify microglia, we quantified morphological changes in microglia at different timepoints in multiple brain regions (cortex, hippocampus, basal forebrain, hindbrain, and cerebellum) in B6 male mice using semi-automated 3D structural analysis. Simultaneously, in a separate group, we monitored wake and sleep stage-specific brain activity using EEG/EMG recordings. During natural sleep-wake cycles, we observed increased microglial complexity (enlarged volume, territorial coverage, and ramification) during wakefulness, characterized by high-frequency theta (8-12 Hz) and gamma activity (30-80 Hz). Conversely, during NREM sleep, which is dominated by delta activity (0.5-4 Hz), microglia displayed reduced complexity. Notably, this pattern was absent in brain regions lacking direct functional connections to areas generating vigilance stage-dependent thalamocortical oscillations. We then extended wakefulness to decouple circadian influence from sleep-wake-specific neuronal activity. This procedure attenuated the decrease in microglial complexity observed during natural sleep, suggesting a crucial role for neuronal activity. Subsequent recovery sleep restored microglial features, independent of the time of day (zeitgeber time). These findings reveal a dynamic interplay between vigilance stage-specific thalamocortical activity and microglial morphology across various brain regions. This suggests a potential role for microglia in sleep regulation and warrants further investigation to understand the underlying mechanisms.

Design and development of different adaptive MPPT controllers for renewable energy systems: a comprehensive analysis.

As of now, all over the world is focusing on the Electric Vehicle (EV) technology because its features are low environmental pollution, less maitainence cost required, high robustness, and good dynamic response. Also, the EVs work continuously until the input fuel is provided to the fuel stack. Here, a Proton Exchange Membrane Fuel Cell (PEMFC) is used as an input source to the electric vehicle system because of its merits fast startup, and quick response. However, the PEMFC gives nonlinear voltage versus current characteristics. As a result, the extraction of maximum power from the fuel stack is very difficult. The main aim of this work is to study different Maximum Power Point Tracking Techniques (MPPT) for the DC-DC converter-fed PEMFC system. The studied MPPT controllers are Adjusted Step Value of Perturb & Observe (ASV with P&O), Adaptive Step Size with Incremental Conductance (ASS with IC), Radial Basis Functional Network (RBFN), Incremental Step-Fuzzy Logic Controller (IS with FLC), Continuous Step Variation based Particle Swarm Optimization (CSV with PSO), and Adaptive Step Value-Cuckoo Search Algorithm (ASV with CSA). The selected MPPT controllers' comprehensive study has been in terms of maximum power extraction, tracking speed of the MPP, settling time of the fuel stack output voltage, oscillations across the MPP, and design complexity. From the comprehensive performance results of the hybrid MPPT controllers, the ASV with CSA technique gives superior performance when equated to the other MPPT controllers.

Activation of D2-like dopamine receptors improves the neuronal network and cognitive function of PPT1KI mice.

Palmitoyl-protein thioesterase 1 (PPT1) is a lysosomal depalmitoylation enzyme that mediates protein posttranslational modifications. Loss-of-function mutation of PPT1 causes a failure of the lysosomal degradation of palmitoylated proteins and results in a congenital disease characterized by progressive neuronal degeneration referred to as infantile neuronal ceroid lipofuscinosis (INCL). A mouse knock-in model of PPT1 (PPT1-KI) was established by introducing the R151X mutation into exon 5 of the PPT1 gene, which exhibited INCL-like pathological lesions. We previously reported that hippocampal γ oscillations were impaired in PPT1 mice. Hippocampal γ oscillations can be enhanced by selective activation of the dopamine D4 receptor (DR4), a dopamine D2-like receptor. In this study, we investigated the changes in DR expression and the effects of dopamine and various DR agonists on neural network activity, cognition and motor function in PPT1KI mice. Cognition and motor defects were evaluated via Y-maze, novel object recognition and rotarod tests. Extracellular field potentials were elicited in hippocampal slices, and neuronal network oscillations in the gamma frequency band (γ oscillations) were induced by perfusion with kainic acid (200 nM). PPT1KI mice displayed progressive impairments in γ oscillations and hippocampus-related memory, as well as abnormal expression profiles of dopamine receptors with preserved expression of DR1 and 3, increased membrane expression of DR4 and decreased DR2 levels. The immunocytochemistry analysis revealed the colocalization of PPT1 with DR4 or DR2 in the soma and large dendrites of both WT and PPT1KI mice. Immunoprecipitation confirmed the interaction between PPT1 and DR4 or DR2. The impaired γ oscillations and cognitive functions were largely restored by the application of exogenous dopamine, the selective DR2 agonist quinpirole or the DR4 agonist A412997. Furthermore, the administration of A412997 (0.5 mg/kg, i.p.) significantly upregulated the activity of CaMKII in the hippocampus of 5-month-old PPT1KI mice. Collectively, these results suggest that the activation of D2-like dopamine receptors improves cognition and network activity in PPT1KI mice and that specific DR subunits may be potential targets for the intervention of neurodegenerative disorders, such as INCL.

Adaptive closed-loop modulation of cortical theta oscillations: Insights into the neural dynamics of navigational decision-making.

Navigational decision-making tasks, such as spatial working memory (SWM), rely highly on information integration from several cortical and sub-cortical regions. Performance in SWM tasks is associated with theta rhythm, including low-frequency oscillations related to movement and memory. The interaction of the ventral hippocampus (vHPC) and medial prefrontal cortex (mPFC), reflected in theta synchrony, is essential in various steps of information processing during SWM. We used a closed-loop neurofeedback (CLNF) system to upregulate theta power in the mPFC and investigate its effects on circuit dynamics and behavior in animal models. Specifically, we hypothesized that enhancing the power of the theta rhythm in the mPFC might improve SWM performance. Animals were divided into three groups: closed-loop (CL), random-loop (RL), and OFF (without stimulation). We recorded local field potential (LFP) in the mPFC while electrical reward stimulation contingent on cortical theta activity was delivered to the lateral hypothalamus (LH), which is considered one of the central reward-associated regions. We also recorded LFP in the vHPC to evaluate the related subcortical neural changes. Results revealed a sustained increase in the theta power in both mPFC and vHPC for the CL group. Our analysis also revealed an increase in mPFC-vHPC synchronization in the theta range over the stimulation sessions in the CL group, as measured by coherence and cross-correlation in the theta frequency band. The reinforcement of this circuit improved spatial decision-making performance in the subsequent behavioral results. Our findings provide direct evidence of the relationship between specific theta upregulation and SWM performance and suggest that theta oscillations are integral to cognitive processes. Overall, this study highlights the potential of adaptive CLNF systems in investigating neural dynamics in various brain circuits.

Magnetotransport and angle-resolved photoemission spectroscopy of MnSb12Te19: a new member of MnSb2nTe3n+1family.

The quest for intrinsically ferromagnetic topological materials is a focal point in the study of topological phases of matter, as intrinsic ferromagnetism plays a vital role in realizing exotic properties such as the anomalous Hall effect (AHE) in quasi-two-dimensional materials, and this stands out as one of the most pressing concerns within the field. Here, we investigate a novel higher order member of the MnSb2nTe3n+1family, MnSb12Te19, for the first time combining magnetotransport and angle-resolved photoemission spectroscopy (ARPES) measurements. Our magnetic susceptibility experiments identify ferromagnetic transitions at temperatureTc= 18.7 K, consistent with our heat capacity measurements (T= 18.8 K). The AHE is observed for the field along thec-axis belowTc. Our study of Shubinikov-de-Haas oscillations provides evidence for Dirac fermions withπBerry phase. Our comprehensive investigation reveals that MnSb12Te19exhibits a FM ground state along with AHE, and hole-dominated transport properties consistent with ARPES measurements.

The phase coherence of cortical oscillations predicts dynamic changes in perceived visibility.

The phase synchronization of brain oscillations plays an important role in visual processing, perceptual awareness, and performance. Yet, the cortical mechanisms underlying modulatory effects of post-stimulus phase coherence and frequency-specific oscillations associated with different aspects of vision are still subject to debate. In this study, we aimed to identify the post-stimulus phase coherence of cortical oscillations associated with perceived visibility and contour discrimination. We analyzed electroencephalogram data from two masking experiments where target visibility was manipulated by the contrast ratio or polarity of the mask under various onset timing conditions (stimulus onset asynchronies, SOAs). The behavioral results indicated an SOA-dependent suppression of target visibility due to masking. The time-frequency analyses revealed significant modulations of phase coherence over occipital and parieto-occipital regions. We particularly identified modulations of phase coherence in the (i) 2-5 Hz frequency range, which may reflect feedforward-mediated contour detection and sustained visibility; and (ii) 10-25 Hz frequency range, which may be associated with suppressed visibility through inhibitory interactions between and within synchronized neural pathways. Taken together, our findings provide evidence that oscillatory phase alignments, not only in the pre-stimulus but also in the post-stimulus window, play a crucial role in shaping perceived visibility and dynamic vision.

Time-frequency analysis of event-related brain recordings: Effect of noise on power.

In neuroscience, time-frequency analysis is widely used to investigate brain rhythms in brain recordings. In event-related protocols, it is applied to quantify how the brain responds to a stimulation repeated over many trials. We here focus on two common measures: the power of the transform for each single trial averaged across trials, avgPOW; and the power of the transform of the average evoked potential, POWavg. We investigate the influence of additive noise on these two measures. We quantify the expected effect using theoretical calculations, simulated data and experimental brain recordings. We also consider the case of color noise. We extract the main factors influencing the effect of noise on POWavg and avgPOW, such as the noise variance, the number of trials, the sampling rate, the type of noise, the type of time-frequency transform and the frequency of interest. When dealing with time-frequency analysis, the impact of noise on the neuroscientist's work can drastically vary depending on these factors. The present results should help researchers improve their understanding and interpretation of time-frequency diagrams, as well as optimize their experimental designs and analyses based on their neuroscientific question.

Resting-State EEG Alterations of Practice-Related Spectral Activity and Connectivity Patterns in Depression.

BACKGROUND: Depression presents with altered energy regulation and neural plasticity. Previous electroencephalography (EEG) studies showed that practice in learning tasks increases power in beta range (13-30 Hz) in healthy subjects but not in those with impaired plasticity. Here, we ascertain whether depression presents with alterations of spectral activity and connectivity before and after a learning task. METHODS: We used publicly available resting-state EEG recordings (64 electrodes) from 122 subjects. Based on Beck Depression Inventory (BDI) scores, they were assigned to either a high BDI (hBDI, BDI > 13, N = 46) or a control (CTL, BDI < 7, N = 75) group. We analyzed spectral activity, theta-beta, and theta-gamma phase-amplitude coupling (PAC) of EEG recorded at rest before and after a learning task. RESULTS: At baseline, compared to CTL, hBDI exhibited greater power in beta over fronto-parietal regions and in gamma over the right parieto-occipital area. At post task, power increased in all frequency ranges only in CTL. Theta-beta and theta-gamma PAC were greater in hBDI at baseline but not after the task. CONCLUSIONS: The lack of substantial post-task growth of beta power in depressed subjects likely represents power saturation due to greater baseline values. We speculate that inhibitory/excitatory imbalance, altered plasticity mechanisms, and energy dysregulation present in depression may contribute to this phenomenon.