Theta Oscillations Research Articles

Lateral prefrontal theta oscillations causally drive a computational mechanism underlying conflict expectation and adaptation.

Adapting our behavior to environmental demands relies on our capacity to perceive and manage potential conflicts within our surroundings. While evidence implicates the involvement of the lateral prefrontal cortex and theta oscillations in detecting conflict stimuli, their causal role in conflict expectation remains elusive. Consequently, the exact computations and neural mechanisms underlying these cognitive processes still need to be determined. We employed an integrative approach involving cognitive computational modeling, fMRI, TMS, and EEG to establish a causal link between oscillatory brain function, its neurocomputational role, and the resulting conflict processing and adaptation behavior. Our results reveal a computational process underlying conflict expectation, which correlates with BOLD-fMRI and theta activity in the superior frontal gyrus (SFG). Modulation of theta activity via rhythmic TMS applied over the SFG induces endogenous theta activity, which in turn enhances computations associated with conflict expectation. These findings provide evidence for the causal involvement of SFG theta activity in learning and allocating cognitive resources to address forthcoming conflict stimuli.

Cell-type specific contributions to theta-gamma coupled rhythms in the hippocampus

Abstract Distinct inhibitory cell types participate in cognitively relevant nested brain rhythms, and particular changes in such rhythms are known to occur in disease states. Specifically, the co-expression of theta and gamma rhythms in the hippocampus is believed to represent a general coding scheme, but cellular-based generation mechanisms for these coupled rhythms are currently unclear. We develop a population rate model of the CA1 hippocampus that encompasses circuits of three inhibitory cell types (bistratified cells, parvalbumin (PV)-expressing and cholecystokinin (CCK)-expressing basket cells) and pyramidal cells to examine this. We constrain parameters and perform numerical and theoretical analyses. The theory, in combination with the numerical explorations, predicts circuit motifs and specific cell-type mechanisms that are essential for the co-existence of theta and gamma oscillations. We find that CCK-expressing basket cells initiate the coupled rhythms and regularize theta, and PV-expressing basket cells enhance both theta and gamma rhythms. Pyramidal and bistratified cells govern the generation of theta rhythms, and PV-expressing basket and pyramidal cells play dominant roles in controlling theta frequencies. Our circuit motifs for theta-gamma coupled rhythm generation could be applicable to other brain regions.

Supramammillary Theta Oscillations in Water Maze Learning.

The supramammillary nucleus (SuM) in the hypothalamus, in conjunction with the hippocampus (HPC), has been implicated through theta oscillations in various brain functions ranging from locomotion to learning and memory. While the indispensable role of the SuM in HPC theta generation in anesthetized animals is well-characterized, the SuM is not always necessary for HPC theta in awake animals. This raises questions on the precise behavioral relevance of SuM theta activity and its interaction with HPC theta activity. We used simultaneously recorded SuM and HPC local field potentials (LFPs) in a one-day water maze (WM) learning paradigm in rats (n = 8), to show that theta activities recorded from the SuM itself were not positively correlated with locomotor (swimming) speed nor acceleration, but the individual relationship between acceleration and SuM theta frequency is correlated with WM learning rates. In contrast, we found that SuM-HPC theta phase coherence is strongly correlated with swimming speed and acceleration, but these do not relate to WM learning. SuM-HPC-directed coherence analysis demonstrated no swimming kinetics nor learning rate associations, but revealed that periods of high SuM-HPC theta phase coherence are driven by the SuM at relatively low (~6.2 Hz) frequencies. Additionally, we demonstrate that the SuM and the HPC also engage in non-random, non-coherent phase coupling modes where either structure preferentially displays a ± 2 Hz difference with the other. Our data indicate SuM theta LFPs do not appear to be related to either speed coding or spatial learning in swimming rats and display non-random out-of-phase theta frequency coupling with the HPC.

Neurophysiological dynamics of metacontrol states: EEG insights into conflict regulation

Understanding the neural mechanisms underlying metacontrol and conflict regulation is crucial for insights into cognitive flexibility and persistence. This study employed electroencephalography (EEG), EEG-beamforming and directed connectivity analyses to explore how varying metacontrol states influence conflict regulation at a neurophysiological level. Metacontrol states were manipulated by altering the frequency of congruent and incongruent trials across experimental blocks in a modified flanker task, and both behavioral and electrophysiological measures were analyzed. Behavioral data confirmed the experimental manipulation's efficacy, showing an increase in persistence bias and a reduction in flexibility bias during increased conflict regulation. Electrophysiologically, theta band activity paralleled the behavioral data, suggesting that theta oscillations reflect the mismatch between expected metacontrol bias and actual task demands. Alpha and beta band dynamics differed across experimental blocks, though these changes did not directly mirror behavioral effects. Post-response alpha and beta activity were more pronounced in persistence-biased states, indicating a neural reset mechanism preparing for future cognitive demands. By using a novel artificial neural networks method, directed connectivity analyses revealed enhanced inter-regional communication during persistence states, suggesting stronger top-down control and sensorimotor integration. Overall, theta band activity was closely tied to metacontrol processes, while alpha and beta bands played a role in resetting the neural system for upcoming tasks. These findings provide a deeper understanding of the neural substrates involved in metacontrol and conflict monitoring, emphasizing the distinct roles of different frequency bands in these cognitive processes.

Study of the Brain Functional Connectivity Processes During Multi-Movement States of the Lower Limbs.

Studies using source localization results have shown that cortical involvement increased in treadmill walking with brain-computer interface (BCI) control. However, the reorganization of cortical functional connectivity in treadmill walking with BCI control is largely unknown. To investigate this, a public dataset, a mobile brain-body imaging dataset recorded during treadmill walking with a brain-computer interface, was used. The electroencephalography (EEG)-coupling strength of the between-region and within-region during the continuous self-determinant movements of lower limbs were analyzed. The time-frequency cross-mutual information (TFCMI) method was used to calculate the coupling strength. The results showed the frontal-occipital connection increased in the gamma and delta bands (the threshold of the edge was >0.05) during walking with BCI, which may be related to the effective communication when subjects adjust their gaits to control the avatar. In walking with BCI control, the results showed theta oscillation within the left-frontal, which may be related to error processing and decision making. We also found that between-region connectivity was suppressed in walking with and without BCI control compared with in standing states. These findings suggest that walking with BCI may accelerate the rehabilitation process for lower limb stroke.

The Mindful Brain at Rest: Neural Oscillations and Aperiodic Activity in Experienced Meditators

Abstract Objectives Previous research has demonstrated that mindfulness meditation is associated with a variety of benefits, including improved mental health. Researchers have suggested these benefits may be underpinned by differences in neural oscillations. However, previous studies measuring neural oscillations have not controlled for non-oscillatory neural activity, the power spectrum of which follows a 1/f distribution (whereby the power of neural activity at each frequency is inversely proportional to that frequency (such that as frequency increases, power decreases)) and contributes to power measurements within oscillation frequencies of interest. We applied recently developed methods to determine if past findings related to neural oscillations in meditation are present even after controlling for non-oscillatory 1/f activity. Method Forty-eight experienced meditators and 44 demographically matched non-meditators provided resting electroencephalography (EEG) recordings. Whole-scalp EEG comparisons (topographical ANOVAs) were used to test for differences between meditators and non-meditators in the distribution or global power of activity for theta, alpha, beta, and gamma oscillations, and for the 1/f components slope and intercept using the extended Better OSCillation detection toolbox. Results Results indicated that meditators showed differences in theta, alpha, and gamma oscillatory power compared to non-meditators (all p < 0.05). Post hoc testing suggested that the oscillatory differences were primarily driven by differences in the distribution of neural activity between meditators and non-meditators, rather than differences in the overall power across all scalp electrodes. Conclusions Our results suggest that experience with meditation is associated with higher oscillatory power and altered distributions of theta, alpha, and gamma oscillations, even after controlling for non-oscillatory 1/f activity. Band-specific differences in oscillatory activity may be a mechanism through which meditation leads to neurophysiological benefits. Preregistration This study was not preregistered.

Motor-related oscillations reveal the involvement of sensorimotor processes during recognition memory

Certain object properties may render an item as more memorable than others. One such property is manipulability, or the extent to which an object can be interacted with using our hands. This study sought to determine if the manipulability of an item modulates memory task performance on both a behavioural and neural level. We recorded electroencephalography (EEG) from a large sample of right-handed individuals (N = 53) during a visual item recognition memory task. The task contained stimuli of both high and low manipulability. Analysis focused on activity in the theta rhythm (3.5–7 Hz), which has been implicated in sensorimotor integration, and the mu rhythm (8–14 Hz), the primary oscillation associated with sensorimotor related behaviours. At both encoding and retrieval, theta oscillations were greater over the left motor region for high manipulability stimuli, suggesting that an item’s sensorimotor properties are assessed immediately upon presentation. Manipulability did not affect activity in the mu rhythm. However, mu oscillations over the left motor region were lower during the retrieval of old versus new items and response time was faster for old items, aligning with the cortical reinstatement hypothesis. These results collectively reveal an association between motor oscillations and memory processes, highlight the involvement of sensorimotor processing at both encoding and retrieval.

Dialectics of perisomatic inhibition-The unity and conflict of opposites.

Over the past three decades, a great deal of attention has been paid to the study of perisomatic inhibition and perisomatic inhibitory basket cells. A growing body of experimental evidence points to the leading role of perisomatic inhibitory cells in the generation of oscillatory activity in various frequency ranges. Recently the link between the activity of basket cells and complex behavior has been demonstrated in several laboratories. However, all this is true only for one type of perisomatic inhibitory interneuron-parvalbumin-positive basket cells. Nevertheless, where parvalbumin-positive basket cells are found, there is another type of basket cell, cholecystokinin-positive interneurons. These two types of interneurons share a number of common features: they innervate the same compartments of target neurons and they often receive excitation from the same sources, but they also differ from each other in the synchrony of their GABA release and expression of receptors. The functional role of cholecystokinin-positive basket cells in oscillatory activity is not so obvious. They were thought to be involved in theta oscillations, however recent measurements in free moving animals have put some doubts on this hypothesis. Therefore, an important question is, whether these two types of basket cells work synergistically or perform opposing actions in functional networks? In this mini-review, we attempt to answer this question by putting forward the idea that these two types of basket cells are functionally united as two entities of the same network, and their opposing actions are necessary to maintain rhythmogenesis in a "healthy", physiological range.

Differential modulations of theta and beta oscillations by audiovisual congruency in letter-speech sound integration.

The integration of visual letters and speech sounds is a crucial part of learning to read. Previous studies investigating this integration have revealed a modulation by audiovisual (AV) congruency, commonly known as the congruency effect. To investigate the cortical oscillations of the congruency effects across different oscillatory frequency bands, we conducted a Japanese priming task in which a visual letter was followed by a speech sound. We analyzed the power and phase properties of oscillatory activities in the theta and beta bands between congruent and incongruent letter-speech sound (L-SS) pairs. Our results revealed stronger theta-band (5-7Hz) power in the congruent condition and cross-modal phase resetting within the auditory cortex, accompanied by enhanced inter-trial phase coherence (ITPC) in the auditory-related areas in response to the congruent condition. The observed congruency effect of theta-band power may reflect increased neural activities in the left auditory region during L-SS integration. Additionally, theta ITPC findings suggest that visual letters amplify neuronal responses to the following corresponding auditory stimulus, which may reflect the differential cross-modal influences in the primary auditory cortex. In contrast, decreased beta-band (20-35 Hz) oscillatory power was observed in the right centroparietal regions for the congruent condition. The reduced beta power seems to be unrelated to the processing of AV integration, but may be interpreted as the brain response to predicting auditory sounds during language processing. Our data provide valuable insights by indicating that oscillations in different frequency bands contribute to the disparate aspects of L-SS integration.

Arginine vasopressin induces analgesic effects and inhibits pyramidal cells in the anterior cingulate cortex in spared nerve injured mice.

Neuropathic pain (NP) is a severe disease caused by a primary disease or lesion affecting the somatosensory nervous system. It`s reported that NP is related to the increased activity of glutamatergic pyramidal cells and changed neural oscillations in the anterior cingulate cortex (ACC). Arginine vasopressin (AVP), a neurohypophyseal hormone, has been shown to cause pain-alleviating effects when applied to peripheral system. However, the extent to which, and the mechanisms by which, AVP induces analgesic effects in the central nervous system remain unclear. In the present study, we observed that intranasal delivery of AVP inhibited mechanical pain, thermal pain and spontaneous pain sensitivity in mice with spared nerve injury. Meanwhile, AVP application exclusively reduced the FOS expression in the pyramidal cells but not interneurons in the ACC. In vivo electrophysiological recording of the ACC further showed that AVP application not only inhibited the theta oscillation in local field potential analysis, but also reduced the firing rate of spikes of pyramidal cells in the ACC in neuropathic pain mice. In summary, AVP induce analgesic effects by inhibiting neural theta oscillations and the spiking of pyramidal cells of the ACC in mice with neuropathic pain, which should provide new potential noninvasive methods for clinical treatment of chronic pain.

Theta oscillations in observers’ temporal cortex index postural instability of point-light displays

This study investigates whether postural equilibration follows the same principles of motor resonance as goal-oriented actions, namely, whether an individual activates the same neuronal substrates when experiencing postural perturbation as when observing another individual in this condition. To address this question, we examined electroencephalographic dynamics while subjects observed point-light displays featuring an unstable human display, a stable human display, and their respective scrambled counterparts lacking shape information and biological motion. We focused on theta band (4–7 Hz), which is a fundamental frequency for modulating brain activity during challenging balance tasks and reflects postural stability monitoring. Rather than mirroring activity, our findings suggest an inhibitory response to postural instability. Theta event-related synchronization in the left temporal cortex was dampened for the unstable display as compared to its scramble counterpart and to the stable display. This low theta response coincided with an increase in left temporal-prefrontal connectivity, compatible with top-down inhibitory mechanisms. By contrast, the stronger theta response to the stable display as compared to the unstable one could be due to the difficulty of recognizing low-motion biological stimuli, or alternatively, to a facilitation of stimulus processing and strengthening of the mirroring response. The response facilitation for stable posture, coupled with a diminished response to the unstable display, could contribute to a broader mechanism mitigating postural threats and ensuring stable balance. Future investigations should leverage these findings to explore how posture-related responses correlate with perceptual and motor expertise, and to more clearly define these mechanisms during dynamic social interactions.

Theta-gamma-coupling as predictor of working memory performance in young and elderly healthy people

The relationship between working memory (WM) and neuronal oscillations can be studied in detail using brain stimulation techniques, which provide a method for modulating these oscillations and thus influencing WM. The endogenous coupling between the amplitude of gamma oscillations and the phase of theta oscillations is crucial for cognitive control. Theta/gamma peak-coupled transcranial alternating current stimulation (TGCp-tACS) can modulate this coupling and thus influence WM performance. This study investigated the effects of TGCp-tACS on WM in older adults and compared their responses with those of younger participants from our previous work who underwent the same experimental design. Twenty-eight older subjects underwent both TGCp-tACS and sham stimulation sessions at least 72 h apart. Resting-state electroencephalography (EEG) was recorded before and after the interventions, and a WM task battery with five different WM tasks was performed during the interventions to assess various WM components. Outcomes measured included WM task performance (e.g., accuracy, reaction time (RT)) and changes in power spectral density (PSD) in different frequency bands. TGCp-tACS significantly decreased accuracy and RT on the 10- and 14-point Sternberg tasks and increased RT on the Digit Symbol Substitution Test in older adults. In contrast, younger participants showed a significant increase in accuracy only on the 14-item Sternberg task. Electrophysiological analysis revealed a decrease in delta and theta PSD and an increase in high gamma PSD in both younger and older participants after verum stimulation. In conclusion, theta-gamma coupling is essential for WM and modulation of this coupling affects WM performance. The effects of TGCp-tACS on WM vary with age due to natural brain changes. To better support older adults, the study suggests several strategies to improve cognitive function, including: Adjusting stimulation parameters, applying stimulation to two sites, conducting multiple sessions, and using brain imaging techniques for precise targeting.

Modulation of Cerebellar Oscillations with Subthalamic Stimulation in Patients with Parkinson's Disease.

Deep brain stimulation (DBS) targeting the subthalamic nucleus (STN) has emerged as a potent treatment for alleviating motor symptoms in Parkinson's disease (PD). Despite its effectiveness, the impact of high frequency STN-DBS on cerebellar oscillations remains unclear, posing an intriguing challenge for neural modulation. Given the direct and indirect connections between the STN and cerebellum, we investigated whether STN-DBS affects cerebellar oscillations. To observe the effects of STN-DBS on cerebellar oscillations in patients with PD. We recruited 15 PD patients receiving STN-DBS. Electroencephalographic (EEG) signals were recorded from cerebellar regions during resting-state conditions in both the OFF-DBS and STN-DBS conditions. Our analyses centered on spectral features, particularly theta and beta oscillations, guided by prior research and correlation tests to investigate the relationship between oscillatory changes and motor symptom severity. In the mid-cerebellar (Cbz) region, we observed a significant increase in the relative power in all frequency bands, including theta and beta oscillations during STN-DBS, showing the global effect of DBS. Importantly, the correlation results indicated significant associations between mid-cerebellar (Cbz) beta power during the OFF condition and motor severity, which were not evident during STN-DBS. Interestingly, correlations between beta power and motor severity were not observed at the mid-occipital (Oz) and mid-frontal (Cz) regions. Notably, signal similarity analyses demonstrated no evidence of volume conduction effects between the mid-cerebellar (Cbz) and nearby mid-occipital (Oz) regions. While these findings provide valuable insights into the complex interplay between STN-DBS and neural oscillations, further research is essential to decipher their precise functional significance and clinical implications. Understanding these intricacies may contribute to the optimization of DBS therapies for PD.

Interplay between preclinical indices of obesity and neural signatures of fluid intelligence in youth.

Pediatric obesity rates have quadrupled in the United States, and deficits in higher-order cognition have been linked to obesity, though it remains poorly understood how deviations from normal body mass are related to the neural dynamics serving cognition in youth. Herein, we determine how age- and sex-adjusted measures of body mass index (zBMI) scale with neural activity in brain regions underlying fluid intelligence. Seventy-two youth aged 9-16 years underwent high-density magnetoencephalography while performing an abstract reasoning task. The resulting data were transformed into the time-frequency domain and significant oscillatory responses were imaged using a beamformer. Whole-brain correlations with zBMI were subsequently conducted to quantify relationships between zBMI and neural activity serving abstract reasoning. Our results reveal that participants with higher zBMI exhibit attenuated theta (4-8 Hz) responses in both the left dorsolateral prefrontal cortex and left temporoparietal junction, and that weaker temporoparietal responses scale with slower reaction times. These findings suggest that higher zBMI values are associated with weaker theta oscillations in key brain regions and altered performance during an abstract reasoning task. Thus, future investigations should evaluate neurobehavioral function during abstract reasoning in youth with more severe obesity to identify the potential impact.

Distinct effects of slow and fast theta tACS in enhancing temporal memory

Abstract Temporal memory plays a crucial role in organizing real-life events into meaningful segments. Previous research suggests that the clustering of temporally related information builds on the neural correlates of associative memory, including theta oscillations. Transcranial alternating current stimulation (tACS) provides a means of modulating theta oscillations within associative memory networks, possibly including hippocampal modulation when targeting parietal cortex. Theta oscillations are not limited to a single frequency range, but instead, exhibit functional specialization, with slow theta (3 Hz) implicated in short-term episodic memory formation and fast theta (8 Hz) involved in spatial navigation. This study aimed to investigate the distinct effects of slow and fast theta stimulation on temporal memory. Participants encoded visual objects paired with frame color while receiving tACS stimulation at 8 Hz, 3 Hz, or sham targeting the left parietal cortex. The frame color would change for every eight objects, establishing a context boundary with each color change. Subsequently, participants performed a timeline task to assess temporal memory performance. Results showed that slow, but not fast, theta stimulation led to an enhancement in temporal accuracy (absolute temporal error) compared to sham tACS, in support of our main hypothesis. Under sham stimulation, participants consistently underestimated the temporal position of items presented further away from boundary, compared to those presented at boundary. This finding resembled temporal compression observed during event segmentation. Interestingly, fast, but not slow, theta stimulation reduced this temporal bias (rated position— actual position). This study represents the first tACS evidence for differential contributions of slow versus fast theta to temporal memory formation in humans. We speculate that parietal theta tACS may modulate the hippocampus and facilitate temporal memory formation.

Differential Neural Mechanisms of Feedback Processing in Children with Developmental Language Disorder: An Examination of Midfrontal Theta Connectivity.

Previous research indicates that children with Developmental Language Disorder (DLD) face challenges learning from feedback, resulting in suboptimal performance and learning outcomes. Feedback processing, a key developing executive function, involves cognitive processes critical for goal-directed behavior. This study examined the neural mechanisms underlying feedback processing in school-age children with DLD compared to typically developing (TD) peers, focusing on midfrontal theta band (4-8 Hz) oscillations as an index of cognitive control and error monitoring. We measured midfrontal theta inter-trial coherence (ITC) and inter-site coherence (ISC) at midfrontal (FCz), lateral prefrontal (F3/F4), and lateral central (C3/C4) sites in children with and without DLD (n = 33, age 8-13 years) in response to feedback provision within a Wisconsin Card Sorting Test (WCST) in two time windows (200-400 ms, which is associated with the Feedback-Related Negativity, or FRN, and 400-600 ms, which is associated with the P3a). Children with and without DLD showed elevated midfrontal theta oscillations in response to negative feedback that was followed by successful behavioral adjustments in the FRN time window. Activation in the P3a time window was only found in the TD group. Group differences were also noted in the inter-site coherence (ISC) associated with the effective processing of negative feedback. While in the TD group, effective processing of negative feedback was linked to high connectivity between midfrontal and right sensorimotor regions, in the DLD group, effective processing of negative feedback was associated with high connectivity between midfrontal and left sensorimotor sites. Differential ISC patterns in children with DLD may indicate that they employ alternative or compensatory neural strategies, possibly due to atypical right sensorimotor engagement.

Comparative Electroencephalographic Profile of a New Anesthetic and Anticonvulsant That Is Selective for the GABAAR Slow Receptor Subtype.

Anesthetics like propofol increase electroencephalography (EEG) power in delta frequencies (0.1-4 Hz), with a decrease of power in bandwidths >30 Hz. Propofol is nonselective for gamma amino butyric acid type A receptor subtypes (GABAAR) as it enhances all 3 GABAAR subtypes (slow, fast, and tonic). Our newly developed anesthetic class selectively targets GABAAR-slow synapses to depress brain responsiveness. We hypothesized that a selective GABAAR-slow agonist, KSEB 01-S2, would produce a different EEG signature compared to the broad-spectrum GABAAR agonist (propofol), and tested this using rat EEG recordings. Male rats were studied after Institutional Animal Care and Use Committees (IACUC) approval from the US Army Medical Research Institute of Chemical Defense and the University of Michigan. Rats were anesthetized using isoflurane (3%-5% induction, 1%-3% maintenance) with oxygen at 0.5 to 1.0 L/min. Stainless steel screws were placed in the skull and used to record subcranial cortical EEG signals. After recovery, either propofol or KSEB 01-S2 was administered and effects on EEG signals were analyzed. As previously reported, propofol produced increased power in delta frequencies (0.1-4 Hz) compared to predrug recordings and produced a decrease in EEG power >30 Hz but no significant changes were seen within ±20 seconds of losing the righting reflex. By contrast, KSEB 01-S2 produced a significant increase in theta frequency percent power (median 14.7%, 16.2/13.8, 75/25 confidence interval; to 34.7%, 35/31.8; P < .015) and a significant decrease in low gamma frequency percent power (16.9%, 18.6/15.8; to 5.45%, 5.5/5.39; P < .015) for all rats at ± 20 seconds of loss of consciousness (LOC). Both anesthetics produced a flattening of chaotic attractor plots from nonlinear dynamic analyses, like that produced by volatile and dissociative anesthetics at LOC. KSEB 01-S2 produced a markedly different EEG pattern, with a selective increase observed in the theta frequency range. KSEB 01-S2 also differs markedly in its activity at the GABAAR-slow receptor subtype, suggesting a possible mechanistic link between receptor subtype specificity and EEG frequency band signatures. Increased theta together with depressed gamma frequencies is interesting because GABAAR slow synapses have previously been suggested to underlie theta frequency oscillations, while fast synapses control gamma activity. These reciprocal effects support a previous model for theta and nested gamma oscillations based on inhibitory connections between GABAAR fast and slow interneurons. Although each anesthetic produced a unique EEG response, propofol and KSEB 01-S2 both increased slow wave activity and flattened chaotic attractor plots at the point of LOC.

Improving working memory by electrical stimulation and cross-frequency coupling

Working memory (WM) is essential for the temporary storage and processing of information required for complex cognitive tasks and relies on neuronal theta and gamma oscillations. Given the limited capacity of WM, researchers have investigated various methods to improve it, including transcranial alternating current stimulation (tACS), which modulates brain activity at specific frequencies. One particularly promising approach is theta-gamma peak-coupled-tACS (TGCp-tACS), which simulates the natural interaction between theta and gamma oscillations that occurs during cognitive control in the brain. The aim of this study was to improve WM in healthy young adults with TGCp-tACS, focusing on both behavioral and neurophysiological outcomes. Thirty-one participants completed five WM tasks under both sham and verum stimulation conditions. Electroencephalography (EEG) recordings before and after stimulation showed that TGCp-tACS increased power spectral density (PSD) in the high-gamma region at the stimulation site, while PSD decreased in the theta and delta regions throughout the cortex. From a behavioral perspective, although no significant changes were observed in most tasks, there was a significant improvement in accuracy in the 14-item Sternberg task, indicating an improvement in phonological WM. In conclusion, TGCp-tACS has the potential to promote and improve the phonological component of WM. To fully realize the cognitive benefits, further research is needed to refine the stimulation parameters and account for individual differences, such as baseline cognitive status and hormonal factors.

IpsiHand Brain-Computer Interface Therapy Induces Broad Upper Extremity Motor Rehabilitation in Chronic Stroke.

Chronic hemiparetic stroke patients have very limited benefits from current therapies. Brain-computer interface (BCI) engaging the unaffected hemisphere has emerged as a promising novel therapeutic approach for chronic stroke rehabilitation. This study investigated the effectiveness of contralesionally-controlled BCI therapy in chronic stroke patients with impaired upper extremity motor function. We further explored neurophysiological features of motor recovery driven by BCI. We hypothesized that BCI therapy would induce a broad motor recovery in the upper extremity, and there would be corresponding changes in baseline theta and gamma oscillations, which have been shown to be associated with motor recovery. Twenty-six prospectively enrolled chronic hemiparetic stroke patients performed a therapeutic BCI task for 12 weeks. Motor function assessment data and resting state electroencephalogram signals were acquired before initiating BCI therapy and across BCI therapy sessions. The Upper Extremity Fugl-Meyer assessment served as a primary motor outcome assessment tool. Theta-gamma cross-frequency coupling (CFC) was computed and correlated with motor recovery. Chronic stroke patients achieved significant motor improvement in both proximal and distal upper extremity with BCI therapy. Motor function improvement was independent of Botox application. Theta-gamma CFC enhanced bilaterally over the C3/C4 motor electrodes and positively correlated with motor recovery across BCI therapy sessions. BCI therapy resulted in significant motor function improvement across the proximal and distal upper extremities of patients, which significantly correlated with theta-gamma CFC increases in the motor regions. This may represent rhythm-specific cortical oscillatory mechanism for BCI-driven rehabilitation in chronic stroke patients. Advarra Study: https://classic.clinicaltrials.gov/ct2/show/NCT04338971 and Washington University Study: https://classic.clinicaltrials.gov/ct2/show/NCT03611855.

Neuromodulation and mindfulness as therapeutic treatment in detoxified patients with alcohol use disorder

BackgroundAlcohol use disorder (AUD) poses a significant global health challenge. Traditional management strategies often face high relapse rates, leading to a need for innovative approaches. Mindfulness-based relapse prevention (MBRP) has emerged as a promising intervention to enhance cognitive control, reduce cue-related craving and improve interoceptive processing. Neuroimaging studies suggest that mindfulness training can modulate brain networks associated with these factors, potentially improving treatment outcomes for AUD. Neuroimaging studies suggest that mindfulness training can modulate brain networks linked to these brain functions, potentially improving treatment outcomes for AUD. However, it is unclear how MBRP links to neurophysiological measures such as frontal midline theta oscillations (FMΘ) and whether the beneficial effects of MBRP can be increased by enhancing FMΘ. Here, we will use two different forms of neuromodulation to target and enhance these oscillations, and evaluate their impact on the effectiveness of MBRP.MethodsThis study will employ a four-arm randomized controlled trial to evaluate the synergistic effects of MBRP augmented with transcutaneous vagus nerve stimulation (tVNS) or closed-loop amplitude-modulated transcranial alternating current stimulation (CLAM-tACS) on cognitive control, cue reactivity and interoceptive processing in AUD patients. Participants will undergo six weekly group MBRP sessions and daily individual mindfulness practices. Assessments will include an inhibition task, cue-induced craving task, and heartbeat discrimination task, alongside heart rate variability and 32-channel EEG recordings. Participants will be assessed pre and post treatment, with a three-month follow-up to evaluate long-term effects on abstinence and alcohol consumption.DiscussionThis study will not only elucidate the causal link between FMΘ and efficacy of MBRP, but contribute to a better understanding of how combined psychological and neuromodulation interventions can improve treatment outcomes for AUD, potentially leading to more effective therapeutic strategies. This study also seeks to explore individual differences in response to treatment, which could inform future approaches to AUD management.Trial registrationThis study received approval by the Charité—Universitätsmedizin Berlin Institutional Review Board (EA1/030/23, 10.11.2023). It was registered on ClinicalTrials.gov (NCT06308484).