Frontal Theta Activity Research Articles

Effects of Transcutaneous Vagus Nerve Stimulation (tVNS) on Conflict-Related Behavioral Performance and Frontal Midline Theta Activity

Several previous studies have highlighted the potential of transcutaneous vagus nerve stimulation (tVNS) to enhance executive control of action. In the present study, we tested for effects of tVNS on behavioral performance and frontal midline theta activity during response conflicts. Frontal midline theta reflects transient activation of the posterior midfrontal cortex in situations requiring increased executive control of action. It is an established marker for top-down action control. We carried out a combined behavioral and electroencephalography (EEG) within-subjects experimental study employing a cued go–no-go-change task. Twenty-two healthy young adults participated. We found that tVNS enhanced global behavioral accuracy, i.e., decreased the proportion of erroneous and missed responses, compared with sham (placebo) stimulation, and reduced conflict costs on behavioral performance in go/change response conflicts. Furthermore, in trials eliciting go/stop conflicts, frontal midline theta was enhanced under tVNS. These findings corroborate the potential of tVNS to enhance executive control of action. For the first time, we show an effect of tVNS on frontal midline theta activity, which suggests that tVNS specifically interacts with the neural mechanisms underlying action control. We conclude that tVNS is a promising method to enhance executive control and recommend the further investigation of tVNS as a candidate treatment of clinically relevant executive control deficits.

Diminished Frontal Theta Activity During Gaming in Young Adults With Internet Gaming Disorder.

Cognitive control is essential for flexible, top-down, goal-directed behavior. Individuals with Internet gaming disorder (IGD) are characterized by impaired prefrontal cortex function and cognitive control. This results in an increase in stimulus-driven habitual behavior, particularly related to pathological gaming. In the present study, we investigated the electroencephalographic (EEG) activity in individuals with IGD. Twenty-four individuals with IGD and 35 healthy control (HC) subjects were recruited. We analyzed their EEG activity while the subjects played their favorite game (30–40 min duration). We compared the band power between the two groups. During gaming, the left frontal theta, alpha, and beta band activities were lower in subjects with IGD than in HCs. Moreover, the left frontal theta power negatively correlated with IGD severity. These results indicate that left frontal theta power could be used as a neurophysiological biomarker for the detection of diminished cognitive control patterns in individuals with IGD.

Error-Related Dynamics of Reaction Time and Frontal Midline Theta Activity in Attention Deficit Hyperactivity Disorder (ADHD) During a Subliminal Motor Priming Task.

Post-error slowing (PES) is an established performance monitoring readout. Several previous studies have found that PES is reduced in children and adolescents with attention-deficit hyperactivity disorder (ADHD). We analyzed reaction time data, along with electroencephalography (EEG) data, from a response priming experiment in children and adolescents with ADHD (N = 28) and typically developing (TD) controls (N = 15) between 10 and 17 years of age. We report dynamic reaction time changes before and after errors: whereas TD controls readjusted their response speed to their individual average speed after committing an error, this reaction time adjustment appeared to be delayed and decreased in ADHD patients. In the EEG, error trials were accompanied by increased frontal midline theta activity, which was attenuated in ADHD compared to TD. We conclude that PES has a different time course rather than being fully absent in ADHD and discuss relationships with our EEG findings and potential implications for performance monitoring in ADHD.

Prefrontal theta modulates sensorimotor gamma networks during the reorienting of attention

The ability to execute a motor plan involves spatiotemporally precise oscillatory activity in primary motor (M1) regions, in concert with recruitment of “higher order” attentional mechanisms for orienting toward current task goals. While current evidence implicates gamma oscillatory activity in M1 as central to the execution of a movement, far less is known about top‐down attentional modulation of this response. Herein, we utilized magnetoencephalography (MEG) during a Posner attention‐reorienting task to investigate top‐down modulation of M1 gamma responses by frontal attention networks in 63 healthy adult participants. MEG data were evaluated in the time–frequency domain and significant oscillatory responses were imaged using a beamformer. Robust increases in theta activity were found in bilateral inferior frontal gyri (IFG), with significantly stronger responses evident in trials that required attentional reorienting relative to those that did not. Additionally, strong gamma oscillations (60–80 Hz) were detected in M1 during movement execution, with similar responses elicited irrespective of attentional reorienting. Whole‐brain voxel‐wise correlations between validity difference scores (i.e., attention reorienting trials—nonreorienting trials) in frontal theta activity and movement‐locked gamma oscillations revealed a robust relationship in the contralateral sensorimotor cortex, supplementary motor area, and right cerebellum, suggesting modulation of these sensorimotor network gamma responses by attentional reorienting. Importantly, the validity difference effect in this distributed motor network was predictive of overall motor function measured outside the scanner and further, based on a mediation analysis this relationship was fully mediated by the reallocation response in the right IFG. These data are the first to characterize the top‐down modulation of movement‐related gamma responses during attentional reorienting and movement execution.

Younger and older adults utilize dissociable neural mechanisms to up-regulate encoding of visual long-term memory.

Despite the virtually unlimited capacity of visual long-term memory (VLTM), our ability to encode new visual information into this offline storage fluctuates from moment to moment, thus rendering some information forgotten later in time. Is there any way to monitor this moment-to-moment fluctuation and correct them when needed in real time? Previously we have demonstrated that we can monitor this fluctuation from multiple electroencephalograms (EEG) measures of memory encoding in real time and intervene failed memory encoding by cueing participants to up-regulate (i.e.,“try harder”) memory encoding on the spot, particularly when the ongoing frontal theta (5–7Hz) amplitude was low (Pereira & Fukuda, 2018). In the current study, we examined whether older adults were capable of exerting the same up-regulatory control on VLTM encoding. Interestingly, although older adults exhibited the equivalent efficacy for voluntary up-regulation of VLTM encoding, the underlying neural correlates were qualitatively different from those for younger adults. More precisely, unlike younger adults, the older adults’ efficacy of voluntary up-regulation of VLTM encoding did not depend on the amplitude of ongoing frontal theta activity. Moreover, while the amplitude of the cue-elicited late posterior positivity predicted successful up-regulation of VLTM encoding in younger adults, it was not the case for the older adults. Taken together, our results demonstrate that younger and older adults recruit dissociable neural mechanisms to voluntarily up-regulate VLTM encoding, and thus suggest the importance of age-specific calibration of EEG-based real-time memory intervention.

Behavioural and electrophysiological modulations induced by transcranial direct current stimulation in healthy elderly and Alzheimer’s disease patients: A pilot study

ObjectiveTo investigate whether anodal and cathodal transcranial direct current stimulation (tDCS) can modify cognitive performance and neural activity in healthy elderly and Alzheimer’s disease (AD) patients. MethodsFourteen healthy elderly and twelve AD patients performed a working memory task during an electroencephalogram recording before and after receiving anodal, cathodal, and sham tDCS over the left dorsolateral prefrontal cortex. Behavioural performance, event-related potentials (P200, P300) and evoked cortical oscillations were studied as correlates of working memory. ResultsAnodal tDCS increased P200 and P300 amplitudes in healthy elderly. Cathodal tDCS increased P200 amplitude and frontal theta activity between 150 and 300 ms in AD patients. Improved working memory after anodal tDCS correlated with increased P300 in healthy elderly. In AD patients, slight tendencies between enhanced working memory and increased P200 after cathodal tDCS were observed. ConclusionsFunctional neural modulations were promoted by anodal tDCS in healthy elderly and by cathodal tDCS in AD patients. SignificanceInteraction between tDCS polarity and the neural state (e.g., hyper-excitability exhibited by AD patients) suggests that appropriate tDCS parameters (in terms of tDCS polarity) to induce behavioural improvements should be chosen based on the participant’s characteristics. Future studies using higher sample sizes should confirm and extend the present findings.

Atypical frontal midline theta activity during cognitive control in heroin addicts.

Deficiency in cognitive control has been proposed as a core issue in addictive behavior, and recent advancements in cognitive neuroscience have suggested that frontal midline theta is a mechanism for cognitive control. This study examined frontal midline theta deficits in patients with heroin dependence during a Go/No-go task which explicitly involved cognitive control. Electroencephalography readings were collected from 15 male heroin addicts and 17 demographically matched healthy controls during an equal probability Go/No-go task. The findings revealed that heroin addicts responded significantly slower to the Go stimulus as compared to the healthy control. Heroin addicts also showed less frontal midline theta modulations between the Go and No-go conditions. These findings provided further evidence toward understanding the nature of drug addiction-related cognitive dysfunction.

Selective effects of acute low-grade inflammation on human visual attention

Illness is often accompanied by perceived cognitive sluggishness, a symptom that may stem from immune system activation. The current study used electroencephalography (EEG) to assess how inflammation affected three different distinct attentional processes: alerting, orienting and executive control. In a double-blinded placebo-controlled within-subjects design (20 healthy males, mean age = 24.5, SD = 3.4), Salmonella typhoid vaccination (0.025 mg; Typhim Vi, Sanofi Pasteur) was used to induce transient mild inflammation, while a saline injection served as a placebo-control. Participants completed the Attention Network Test with concurrent EEG recorded 6 h post-injection. Analyses focused on behavioral task performance and on modulation of oscillatory EEG activity in the alpha band (9–12 Hz) for alerting as well as orienting attention and frontal theta band (4–8 Hz) for executive control. Vaccination induced mild systemic inflammation, as assessed by interleukin-6 (IL-6) levels. While no behavioral task performance differences between the inflammation and placebo condition were evident, inflammation caused significant alterations to task-related brain activity. Specifically, inflammation produced greater cue-induced suppression of alpha power in the alerting aspect of attention and individual variation in the inflammatory response was significantly correlated with the degree of alpha power suppression. Notably, inflammation did not affect orienting (i.e., alpha lateralization) or executive control (i.e., frontal theta activity). These results reveal a unique neurophysiological sensitivity to acute mild inflammation of the neural network that underpins attentional alerting functions. Observed in the absence of performance decrements, these novel findings suggest that acute inflammation requires individuals to exert greater cognitive effort when preparing for a task in order to maintain adequate behavioral performance.

2B3-5 Study of individual differences in cognitive control level in SRK model and frontal theta activity

2B3-5 Study of individual differences in cognitive control level in SRK model and frontal theta activity

Antismoking Campaigns’ Perception and Gender Differences: A Comparison among EEG Indices

Human factors' aim is to understand and evaluate the interactions between people and tasks, technologies, and environment. Among human factors, it is possible then to include the subjective reaction to external stimuli, due to individual's characteristics and states of mind. These processes are also involved in the perception of antismoking public service announcements (PSAs), the main tool for governments to contrast the first cause of preventable deaths in the world: tobacco addiction. In the light of that, in the present article, it has been investigated through the comparison of different electroencephalographic (EEG) indices a typical item known to be able of influencing PSA perception, that is gender. In order to investigate the neurophysiological underpinnings of such different perception, we tested two PSAs: one with a female character and one with a male character. Furthermore, the experimental sample was divided into men and women, as well as smokers and nonsmokers. The employed EEG indices were the mental engagement (ME: the ratio between beta activity and the sum of alpha and theta activity); the approach/withdrawal (AW: the frontal alpha asymmetry in the alpha band); and the frontal theta activity and the spectral asymmetry index (SASI: the ratio between beta minus theta and beta plus theta). Results suggested that the ME and the AW presented an opposite trend, with smokers showing higher ME and lower AW than nonsmokers. The ME and the frontal theta also evidenced a statistically significant interaction between the kind of the PSA and the gender of the observers; specifically, women showed higher ME and frontal theta activity for the male character PSA. This study then supports the usefulness of the ME and frontal theta for purposes of PSAs targeting on the basis of gender issues and of the ME and the AW and for purposes of PSAs targeting on the basis of smoking habits.

Enhanced executive attention efficiency after adaptive force control training: Behavioural and physiological results

Attention plays an important role in perception and cognition, and developing an effective method to train and improve attention is an essential and challenging task. In this study, fingertip-based adaptive force control tasks (AFCT) were explored for attention training, and the visual-channel task called an attention network test (ANT) was used to measure the level of attention before and after AFCT. The purposes of this study were to investigate whether AFCT can enhance the attention level on the ANT task and to elucidate the underlying electrophysiological mechanisms. The results showed that the efficiency of the executive control network during ANT was significantly improved by the AFCT training, indicating that the AFCT training may enhance the executive attention level during visual-channel tasks. To measure the behavioural performance during the AFCT training, we used tolerance, variance and duration of the forces to design a comprehensive score of behavioural performance (CSBP), and the electrophysiological mechanisms were also explored using electroencephalography (EEG) recordings. The AFCT and ANT results showed consistency in medial frontal theta activity and in connectivity strength at frontal-parietal regions in the alpha band. These results indicated that the observed attention improvement across tasks executed using different sensory channels may be due to the training of overlapping components of the relevant attention networks. Thus, this study provides further insight into the design of training tasks that stimulate multi-sensory channels, which can be used to improve attention and treat various attention deficit disorders.

When Conflict Cannot be Avoided: Relative Contributions of Early Selection and Frontal Executive Control in Mitigating Stroop Conflict.

When viewing familiar stimuli (e.g., common words), processing is highly automatized such that it can interfere with the processing of incompatible sensory information. At least two mechanisms may help mitigate this interference. Early selection accounts posit that attentional processes filter out distracting sensory information to avoid conflict. Alternatively, late selection accounts hold that all sensory inputs receive full semantic analysis and that frontal executive mechanisms are recruited to resolve conflict. To test how these mechanisms operate to overcome conflict induced by highly automatized processing, we developed a novel version of the color-word Stroop task, where targets and distractors were simultaneously flickered at different frequencies. We measured the quality of early sensory processing by assessing the amplitude of steady-state visually evoked potentials (SSVEPs) elicited by targets and distractors. We also indexed frontal executive processes by assessing changes in frontal theta oscillations induced by color-word incongruency. We found that target- and distractor-related SSVEPs were not modulated by changes in the level of conflict whereas frontal theta activity increased on high compared to low conflict trials. These results suggest that frontal executive processes play a more dominant role in mitigating cognitive interference driven by the automatic tendency to process highly familiar stimuli.

Age-related differences in reallocating cognitive resources when dealing with interruptions

The ability to perform at a high level, even when the task at hand is interrupted by an unrelated secondary task, is central to human information processing. Executive control processes, in particular the reallocation of attentional resources, are crucial for coping with interruptions. Although the age-related decline in cognitive control functions is well described, the consequences of such changes for the ability to deal with interruptions are as of yet unclear. In the present study, we examined behavioral performance as well as electrophysiological parameters associated with executive control processes in older and younger participants using a nested task design: In one third of all trials, an ongoing working memory task was interrupted by a math task. We found that the impact of interruptions on primary task performance was more severe in the older age group. In the EEG, older adults showed stronger frontal midline theta activation and fronto-parietal connectivity in the theta range in response to the cue indicating the relevant attentional set. Younger participants, on the other hand, showed distinct and specific increases in cognitive control as indexed by frontal midline theta in response to the stimulus signaling an upcoming interruption. Overall, the results reveal strategic differences between the age groups, as older participants seem to prioritize the primary task more strongly. The data furthermore indicate that the combination of a rapid succession of events and the decreased ability to shift executive resources renders older adults’ performance particularly vulnerable to the occurrence of interruptions.

The electrophysiology of subjectively perceived memory confidence in relation to recollection and familiarity

Subjectively perceived confidence is critically involved in distinguishing recollection from familiarity in episodic memory retrieval. However, the extent to which recollection and familiarity share similar electrophysiological processes associated with subjectively perceived memory confidence remains an open question. In addition, the role of memory encoding in subjectively perceived confidence during retrieval has not yet been investigated. To address these issues, an EEG study was performed in thirty healthy volunteers. During a memory task, participants encoded a subset of words while rating the words on pleasantness. Memory recognition and subjectively perceived confidence concerning these ‘old’ and additional ‘new’ words was tested. Results showed that during retrieval, correctly classifying an old item with high subjectively perceived confidence was associated with a parietal ERP and parietal theta power, while frontal theta activity was related to high-confident novelty processing. During the memory encoding phase, a parietal ERP and frontal theta oscillations were related to subsequent subjectively perceived memory confidence. Our findings provide the first evidence that subjectively perceived memory confidence is associated with distinct electrophysiological correlates during both memory encoding and retrieval.

Anodal tDCS affects neuromodulatory effects of the norepinephrine system on superior frontal theta activity during response inhibition.

Medial and superior frontal theta oscillations are important for response inhibition. The norepinephrine (NE) system has been shown to modulate these oscillations possibly via gain control mechanisms, which depend on the modulation of neuron membrane potentials. Because the latter are also modulated by tDCS, the interrelation of tDCS and NE effects on superior frontal theta band activity needs investigation. We test the hypothesis that anodal tDCS affects modulatory effects of the NE system on theta band activity during inhibitory control in superior frontal regions. Using EEG beamforming, theta band activity in the superior frontal gyrus (SFG) was integrated (correlated) with the pupil diameter data as an indirect index of NE activity. In a within-subject design, healthy participants completed a response inhibition task in two sessions in which they received 2mA anodal tDCS over the vertex, or sham stimulation. There were no behavioral effects of anodal tDCS. Yet, tDCS affected correlations between SFG theta band activity time course and the pupil diameter time course. Correlations were evident after sham stimulation (r = .701; p < .004), but absent after anodal tDCS. The observed power of this dissociation was above 95%. The data suggest that anodal tDCS may eliminate neuromodulatory effects, likely of the NE system, on theta band activity during response inhibition in a structure of the response inhibition network. The NE system and tDCS seem to target similar mechanisms important for cognitive control in the prefrontal cortex. The results provide a hint why tDCS often fails to induce overt behavioral effects and shows that neurobiological systems, which may exert similar effects as tDCS on neural processes should closely be monitored in tDCS experiments.

Frontal theta predicts specific cognitive control-induced behavioural changes beyond general reaction time slowing

Investigations into the neurophysiological underpinnings of control suggest that frontal theta activity is increased with the need for control. However, these studies typically show this link by reporting associations between increased theta and RT slowing – a process that is contemporaneous with cognitive control but does not strictly reflect the specific use of control. In this study, we assessed frontal theta responses that underpinned the switch cost in task switching – a specific index of cognitive control that does not rely exclusively on RT slowing. Here, we utilised a single-trial regression approach to assess 1) how cognitive control demands beyond simple RT slowing were linked to midfrontal theta and 2) whether midfrontal theta effects remained stable over time. In a large cohort that included a longitudinal subsample, we found that midfrontal theta was modulated by switch costs, with enhanced theta power when preparing to switch vs. repeating a task. These effects were reliable after a two-year interval (Cronbach's α.39-0.74). In contrast, we found that trial-by-trial modulations of midfrontal theta power predicted the size of the switch cost – so that switch trials with increased theta produced smaller switch costs. Interestingly, these relationships between theta and behaviour were less stable over time (Cronbach's α 0-0.61), with participants first using both delta and theta bands to influence behaviour whereas after two years only theta associations with behaviour remained. Together, these findings suggest midfrontal theta supports the need for control beyond simple RT slowing and reveal that midfrontal theta effects remain relatively stable over time.

Post-encoding frontal theta activity predicts incidental memory in the reward context.

Memories for daily events require that individuals integrate initial fragile traces of events over time. Recent evidence suggests that reward anticipation enhances memory performance and amplifies frontal theta activity for remembered items vs. forgotten items. However, little is known about how incidental rewards after item presentation retrospectively modulate memory and the neural basis of this processing. Here, we used EEG combined with an incidental memory task to study how incidental reward association biased the post-encoding process. In the anticipatory stage, participants saw photos in win, loss and neutral contexts. Each photo was presented in a color frame that indicated the incentive condition (win vs. loss vs. neutral) and participants were asked to make a binary choice to predict whether the photo was associated with the left/right button. Feedback was presented to indicate arbitrary correctness and monetary outcomes. Recognition memory was tested after a short delay. During the encoding phase, left central-parietal theta power predicted subsequent memory performance in the win context. The post-encoding theta power at right central-frontal and central-parietal sites predicted later memory performance only in the win context. The size of frontal post-encoding related theta activity in the win context was correlated with the discriminate accuracy of the test stimulus. Our results suggest that post-encoding theta activity is closely linked to reward-based associative learning, providing evidence of a potential post-encoding mechanism of information binding.

SU114 - EARLY SEXUAL ASSAULTIVE TRAUMA, POLYGENIC RISK FOR AUD/CUD, AND NEURAL RESPONSE INHIBITION IN ADOLESCENCE AND YOUNG ADULTS: TRAJECTORIES OF FRONTAL OSCILLATIONS DURING A GO/NOGO TASK

Background Trauma, particularly when experienced early in life, may alter brain and concurrent cognitive, affective and behavioral development, thereby increasing risk for substance use disorders and related psychopathology. While research indicates that genetic factors may exacerbate these vulnerabilities, few studies have empirically examined these effects using relatively large longitudinal and genetically informative developmental samples with dense phenotyping in multiple domains. Methods The association of early assaultive, non-assaultive, and sexual-assaultive experiences prior to age 10 with developmental trajectories of neurophysiological functioning during response inhibition (frontal theta and posterior delta activity during an equal probability Go/NoGo task) were examined, using data from the Collaborative Study of the Genetics of Alcoholism (COGA) prospective cohort, comprising offspring from high-risk and comparison families who were aged 12–22 at enrollment and who have been sought for interview every 2 years (only those with 3+ interviews were included in the present analyses, N: 3,030). Interactions with early trauma exposures and polygenic risk for Alcohol and Cannabis Use Disorders (AUD, CUD) based on recently published GWAS data, were examined. Additionally, associations of neurophysiological functioning with AUD, CUD, Externalizing (EXT) and Internalizing (INT) psychopathology measured at each individual's last assessment were examined. Models were adjusted for age, gender, self-reported race/ethnicity, parental alcohol use disorders, and participants' own alcohol and cannabis use. Results Individuals exposed to sexual assaultive trauma prior to age 10 had altered developmental trajectories of NoGo frontal theta; the typical developmental change in frontal theta activity observed throughout adolescence and young adulthood occurred at a slower rate among those who had been exposed to early sexual assault, but not other types of trauma, compared to those who were not exposed (controlling for other types of assaultive and non-assaultive trauma exposure). Importantly, effects remained significant after accounting for parental history of AUD and participants’ own alcohol and cannabis use. Associations were more robust for participants with greater polygenic risk for AUD, but not CUD. Further, changes in NoGo frontal theta development was associated with increased risk for AUD and INT (mood disorders and suicidal ideation), but not CUD or EXT (conduct disorder, oppositional defiant disorder). Post-hoc analyses showed that early sexual assault was associated with higher rates of impulsivity (Barrett Impulsivity Scale) and sensation seeking (Zuckerman's Sensation Seeking Scale). Discussion Findings support the hypothesis that childhood sexual assault may influence young adult AUD and INT via alterations in genetic, brain and behavioral development in adolescence and young adulthood. However, future studies are needed to disentangle complex interactions among genetic and psycho-social influences on neurobiological development.

FMRI BOLD Correlates of EEG Independent Components: Spatial Correspondence With the Default Mode Network

Goal: We aimed to identify electroencephalographic (EEG) signal fluctuations within independent components (ICs) that correlate to spontaneous blood oxygenation level dependent (BOLD) activity in regions of the default mode network (DMN) during eyes-closed resting state.Methods: We analyzed simultaneously acquired EEG and functional magnetic resonance imaging (fMRI) eyes-closed resting state data in a convenience sample of 30 participants. IC analysis (ICA) was used to decompose the EEG time-series and common ICs were identified using data-driven IC clustering across subjects. The IC time courses were filtered into seven frequency bands, convolved with a hemeodynamic response function (HRF) and used to model spontaneous fMRI signal fluctuations across the brain. In parallel, group ICA analysis was used to decompose the fMRI signal into ICs from which the DMN was identified. Frequency and IC cluster associated hemeodynamic correlation maps obtained from the regression analysis were spatially correlated with the DMN. To investigate the reliability of our findings, the analyses were repeated with data collected from the same subjects 1 year later.Results: Our results indicate a relationship between power fluctuations in the delta, theta, beta and gamma frequency range and the DMN in different EEG ICs in our sample as shown by small to moderate spatial correlations at the first measurement (0.234 < |r| < 0.346, p < 0.0001). Furthermore, activity within an EEG component commonly identified as eye movements correlates with BOLD activity within regions of the DMN. In addition, we demonstrate that correlations between EEG ICs and the BOLD signal during rest are in part stable across time.Discussion: We show that ICA source separated EEG signals can be used to investigate electrophysiological correlates of the DMN. The relationship between the eye movement component and the DMN points to a behavioral association between DMN activity and the level of eye movement or the presence of neuronal activity in this component. Previous findings of an association between frontal midline theta activity and the DMN were replicated.

Load modulates the alpha and beta oscillatory dynamics serving verbal working memory

A network of predominantly left-lateralized brain regions has been linked to verbal working memory (VWM) performance. However, the impact of memory load on the oscillatory dynamics serving VWM is far less understood. To further investigate this, we had 26 healthy adults perform a high-load (6 letter) and low-load (4 letter) variant of a VWM task while undergoing magnetoencephalography (MEG). MEG data were evaluated in the time-frequency domain and significant oscillatory responses spanning the encoding and maintenance phases were reconstructed using a beamformer. To determine the impact of load on the neural dynamics, the resulting images were examined using paired-samples t-tests and virtual sensor analyses. Our results indicated stronger increases in frontal theta activity in the high- relative to low-load condition during early encoding. Stronger decreases in alpha/beta activity were also observed during encoding in bilateral posterior cortices during the high-load condition, and the strength of these load effects increased as encoding progressed. During maintenance, stronger decreases in alpha activity in the left inferior frontal gyrus, middle temporal gyrus, supramarginal gyrus, and inferior parietal cortices were detected during high- relative to low-load performance, with the strength of these load effects remaining largely static throughout maintenance. Finally, stronger increases in occipital alpha activity were observed during maintenance in the high-load condition, and the strength of these effects grew stronger with time during the first half of maintenance, before dissipating during the latter half of maintenance. Notably, this was the first study to utilize a whole-brain approach to statistically evaluate the temporal dynamics of load-related oscillatory differences during encoding and maintenance processes, and our results highlight the importance of spatial, temporal, and spectral specificity in this regard.