Alpha Suppression Research Articles

Mindfulness Meditators Do Not Show Differences in Electrophysiological Measures of Error Processing

Mindfulness meditation may improve attention and self-regulation. One component of attention and self-regulation that may allow these improvements is performance monitoring. Neural correlates of performance monitoring can be objectively measured with electroencephalogram (EEG) via the error-related negativity (ERN) and error positivity (Pe). Previous research assessing the ERN and Pe in meditators has resulted in inconsistent findings; some have reported alteration in peak amplitudes from both very brief meditation practice and long-term meditation practice, while others have failed to provide evidence for differences in the ERN or Pe. However, recently developed EEG analysis techniques allow for more rigorous analyses than have been used in past investigations. The current study measured the ERN and Pe, as well as post-error alpha suppression, during a Go/Nogo task, and emotional and colour Stroop tasks. The measures were compared between 22 experienced meditators (mean of 8 years of practice) and 20 healthy controls. The results suggested no differences in the ERN, Pe, or post-error alpha suppression (all p > 0.05), even when varying multiple analysis parameters. The study showed equivalent statistical power to previous research, and > 85% power to detect medium effect sizes present in previous research. Bayes Factor analysis indicated the null hypotheses were > 3.5 more likely than any of the alternative hypotheses for the ERN or Pe. These results suggest that meditation may not alter neural activity related to error processing, despite prior research suggesting that it does.

Mental Simulation of Facial Expressions: Mu Suppression to the Viewing of Dynamic Neutral Face Videos.

The mirror neuron network (MNN) has been proposed as a neural substrate of action understanding. Electroencephalography (EEG) mu suppression has commonly been studied as an index of MNN activity during execution and observation of hand and finger movements. However, in order to establish its role in higher order processes, such as recognizing and sharing emotions, more research using social emotional stimuli is needed. The current study aims to contribute to our understanding of the sensitivity of mu suppression to facial expressions. Modulation of the mu and occipital alpha (8–13 Hz) rhythms was calculated in 22 participants while they observed dynamic video stimuli, including emotional (happy and sad) and neutral (mouth opening) facial expressions, and non-biological stimulus (kaleidoscope pattern). Across the four types of stimuli, only the neutral face was associated with a significantly stronger mu suppression than the non-biological stimulus. Occipital alpha suppression was significantly greater in the non-biological stimulus than all the face conditions. Source estimation standardized low resolution electromagnetic tomography (sLORETA) analysis comparing the neural sources of mu/alpha modulation between neutral face and non-biological stimulus showed more suppression in the central regions, including the supplementary motor and somatosensory areas, than the more posterior regions. EEG and source estimation results may indicate that reduced availability of emotional information in the neutral face condition requires more sensorimotor engagement in deciphering emotion-related information than the full-blown happy or sad expressions that are more readily recognized.

Humans strategically shift decision bias by flexibly adjusting sensory evidence accumulation.

Decision bias is traditionally conceptualized as an internal reference against which sensory evidence is compared. Instead, we show that individuals implement decision bias by shifting the rate of sensory evidence accumulation toward a decision bound. Participants performed a target detection task while we recorded EEG. We experimentally manipulated participants' decision criterion for reporting targets using different stimulus-response reward contingencies, inducing either a liberal or a conservative bias. Drift diffusion modeling revealed that a liberal strategy biased sensory evidence accumulation toward target-present choices. Moreover, a liberal bias resulted in stronger midfrontal pre-stimulus 2-6 Hz (theta) power and suppression of pre-stimulus 8-12 Hz (alpha) power in posterior cortex. Alpha suppression in turn was linked to the output activity in visual cortex, as expressed through 59-100 Hz (gamma) power. These findings show that observers can intentionally control cortical excitability to strategically bias evidence accumulation toward the decision bound that maximizes reward.

A P300-Based Brain-Computer Interface for Improving Attention.

A Brain-computer Interface (BCI) can be used as a neurofeedback training tool to improve cognitive performance. BCIs aim to improve the effectiveness and efficiency of the conventional neurofeedback methods by focusing on the self-regulation of individualized neuromarkers rather than generic ones in a graphically appealing training environment. In this work, for the first time, we have modified a widely used P300-based speller BCI and used it as an engaging neurofeedack training game to enhance P300. According to the user's performance the game becomes more difficult in an adaptive manner, requiring the generation of a larger and stronger P300 (i.e., in terms of total energy) in response to target stimuli. Since the P300 is generated naturally without conscious effort in response to a target trial, unlike many rhythm-based neurofeedback tools, the ability to control the proposed P300-based neurofeedback training is obtained after a short calibration without undergoing tedious trial and error sessions. The performance of the proposed neurofeedback training was evaluated over a short time scale (approximately 30 min training) using 28 young adult participants who were randomly assigned to either the experimental group or the control group. In summary, our results show that the proposed P300-based BCI neurofeedback training yielded a significant enhancement in the ERP components of the target trials (i.e., 150–550 ms after the onset of stimuli which includes P300) as well as attenuation in the corresponding ERP components of the non-target trials. In addition, more centro-parietal alpha suppression was observed in the experimental group during the neurofeedback training as well as a post-training spatial attention task. Interestingly, a significant improvement in the response time of a spatial attention task performed immediately after the neurofeedback training was observed in the experimental group. This paper, as a proof-of-concept study, suggests that the proposed neurofeedback training tool is a promising tool for improving attention particularly for those who are at risk of attention deficiency.

Lateralized Suppression of Alpha-Band EEG Activity As a Mechanism of Target Processing.

Alpha-band (8-12 Hz) EEG activity has been linked to visual attention since the earliest EEG studies. More recent studies using spatial cuing paradigms have shown that alpha is suppressed over the hemisphere contralateral to a to-be-attended location, suggesting that alpha serves as a mechanism of preparatory attention. Here, we demonstrate that alpha also plays a role in active target processing. EEG activity was recorded from a group of healthy male and female human subjects in two visual search experiments. In addition to alpha activity, we also assessed the N2pc event-related potential component, a lateralized transient EEG response that has been tightly linked with the focusing of attention on visual targets. We found that the visual search targets triggered both an N2pc component and a suppression of alpha-band activity that was greatest over the hemisphere contralateral to the target (which we call "target-elicited lateralized alpha suppression" or TELAS). In Experiment 1, both N2pc and TELAS were observed for targets presented in the lower visual field but were absent for upper-field targets. However, these two lateralized effects had different time courses and they responded differently to manipulations of crowding in Experiment 2. These results indicate that lateralized alpha-band activity is involved in active target processing and is not solely a preparatory mechanism and also that TELAS and N2pc reflect a related but separable neural mechanism of visuospatial attention.SIGNIFICANCE STATEMENT The very first EEG studies demonstrated that alpha-band (8-12 Hz) EEG oscillations are suppressed when people attend to visual information and more recent research has shown that cuing an individual to expect a target at a specific location produces lateralized suppression in the contralateral hemisphere. Therefore, lateralized alpha may serve as a preparatory mechanism. In the present study, we found that a similar lateralized alpha effect is triggered by the appearance of a visual target even though the location could not be anticipated, demonstrating that alpha also serves as an active mechanism of target processing. Moreover, we found that alpha lateralization can be dissociated from other lateralized measures of target selection, indicating that it reflects a distinct mechanism of attention.

Theta-gamma coupling binds visual perceptual features in an associative memory task

It is an integral function of the human brain to sample novel information from the environment and to integrate them into existing representations. Recent evidence suggests a specific role for the theta rhythm (4–8 Hz) in mnemonic processes and the coupling between the theta and the gamma rhythm (40–120 Hz) in ordering and binding perceptual features during encoding. Furthermore, decreases in the alpha rhythm (8–12 Hz) are assumed to gate perceptual information processes in semantic networks. In the present study, we used an associative memory task (object-color combinations) with pictures versus words as stimuli (high versus low visual information) to separate associative memory from visual perceptual processes during memory formation. We found increased theta power for later remembered versus later forgotten items (independent of the color judgement) and an increase in phase-amplitude coupling between frontal theta and fronto-temporal gamma oscillations, specific for the formation of picture-color associations. Furthermore, parietal alpha suppression and gamma power were higher for pictures compared to words. These findings support the idea of a theta-gamma code in binding visual perceptual features during encoding. Furthermore, alpha suppression likely reflects perceptual gating processes in semantic networks and is insensitive to mnemonic and associative binding processes. Gamma oscillations may promote visual perceptual information in visual cortical networks, which is integrated into existing representations by prefrontal control processes, working at a theta pace.

Alterations in oscillatory cortical activity indicate changes in mnemonic processing during continuous item recognition.

The classification of repeating stimuli as either old or new is a general mechanism of everyday perception. However, the cortical mechanisms underlying this process are not fully understood. In general, mnemonic processes are thought to rely on changes in oscillatory brain activity across several frequencies as well as their interaction. Lower frequencies, mainly theta-band (3-7Hz) and alpha-band (8-14Hz) activity, are attributed to executive control and resource management, respectively; whereas recent studies revealed higher frequencies, e.g. gamma-band (> 25Hz) activity, to reflect the activation of cortical object representations. Furthermore, low-frequency phase to high-frequency amplitude coupling (PAC) was recently found to coordinate the involved mnemonic networks. To further unravel the processes behind memorization of repeatedly presented stimuli, we applied a continuous item recognition task with up to five presentations per item (mean time between repetitions ~ 10 s) while recording high-density EEG. We examined spectral amplitude modulations as well as PAC. We observed theta amplitudes reaching a peak at second presentation, a reduction of alpha suppression after second presentation, decreased response time, as well as reduced theta-gamma PAC (3 to 7 to - 30 to 45Hz) at frontal sites after third presentation. We conclude a shift from an explicit- to an implicit-like mnemonic processing, occurring around third presentation, with theta power to signify encoding of repetition-based episodic information and PAC as a neural correlate of the coordination of local neural networks.

EEG data collection in children with ASD: The role of state in data quality and spectral power

BackgroundElectroencephalography can elucidate neurobiological mechanisms underlying heterogeneity in ASD. Studying the full range of children with ASD introduces methodological challenges stemming from participants’ difficulties tolerating the data collection process, leading to diminished EEG data retention and increased variability in participant ‘state’ during the recording. Quantifying state will improve data collection methods and aide in interpreting results. ObjectivesObservationally quantify participant state during the EEG recording; examine its relationship to child characteristics, data retention and spectral power. MethodsParticipants included 5–11 year-old children with ASD (N = 39) and age-matched TD children (N = 16). Participants were acclimated to the EEG environment using behavioral strategies. EEG was recorded while participants watched a video of bubbles. Participant ‘state’ was rated using a Likert scale (Perceived State Rating: PSR). ResultsParticipants with ASD had more elevated PSR than TD participants. Less EEG data were retained in participants with higher PSR scores, but this was not related to age or IQ. TD participants had higher alpha power compared with the ASD group. Within the ASD group, participants with high PSR had decreased frontal alpha power. ConclusionsGiven supportive strategies, EEG data was collected from children with ASD across cognitive levels. Participant state influenced both EEG data retention and alpha spectral power. Alpha suppression is linked to attention and vigilance, suggesting that these participants were less ‘at rest’. This highlights the importance of considering state when conducting EEG studies with challenging participants, both to increase data retention rates and to quantify the influence of state on EEG variables.

Empathic Cognitions Affected by Undetectable Social Chemosignals: An EEG Study on Visually Evoked Empathy for Pain in an Auditory and Chemosensory Context.

Reduction of mu activity within the EEG is an indicator of cognitive empathy and can be generated in response to visual depictions of others in pain. The current study tested whether this brain response can be modulated by an auditory and a chemosensory context. Participants observed pictures of painful and non-painful actions while pain associated and neutral exclamations were presented (Study 1, N = 30) or while chemosensory stimuli were presented via a constant flow olfactometer (Study 2, N = 22). Chemosensory stimuli were sampled on cotton pads while donors participated in a simulated job interview (stress condition) or cycled on a stationary bike (sport condition). Pure cotton was used as a control. The social chemosignals could not be detected as odors. Activity within the 8–13 Hz band at electrodes C3, C4 (mu activity) and electrodes O1, O2 (alpha-activity) was calculated using Fast-Fourier-Transformation (FFT). As expected, suppression of power in the 8–13 Hz band was stronger when painful as compared to non-painful actions were observed (Study 1, p = 0.020; Study 2, p = 0.005). In addition, as compared to the neutral auditory and chemosensory context, painful exclamations (Study 1, p = 0.039) and chemosensory stress signals (Study 2, p = 0.014) augmented mu-/alpha suppression also in response to non-painful pictures. The studies show that processing of social threat-related information is not dominated by visual information. Rather, cognitive appraisal related to empathy can be affected by painful exclamations and subthreshold chemosensory social information.

Neural correlates of time distortion in a preaction period.

An intention to move distorts the perception of time. For example, a visual stimulus presented during the preparation of manual movements is perceived longer than actual. Although neural mechanisms underlying this action-induced time distortion have been unclear, here we propose a new model in which the distortion is caused by a sensory-motor interaction mediated by alpha rhythm. It is generally known that viewing a stimulus induces a reduction in amplitude of occipital 10-Hz wave ("alpha-blocking"). Preparing manual movements are also known to reduce alpha power in the motor cortex ("mu-suppression"). When human participants prepared movements while viewing a stimulus, we found that those two types of classical alpha suppression interacted in the third (time-processing) region in the brain, inducing a prominent decrease in alpha power in the supplementary motor cortex (SMA). Interestingly, this alpha suppression in the SMA occurred in an asymmetric manner (such that troughs of alpha rhythm was more strongly suppressed than peaks), which can produce a gradual increase (slow shift of baseline) in neural activity. Since the neural processing in the SMA encodes a subjective time length for a sensory event, the increased activity in this region (by the asymmetric alpha suppression) would cause an overestimation of elapsed time, resulting in the action-induced time distortion. Those results showed a unique role of alpha wave enabling communications across distant (visual, motor, and time-processing) regions in the brain and further suggested a new type of sensory-motor interaction based on neural desynchronization (rather than synchronization).

Priority Switches in Visual Working Memory are Supported by Frontal Delta and Posterior Alpha Interactions.

Visual working memory (VWM) distinguishes between representations relevant for imminent versus future perceptual goals. We investigated how the brain sequentially prioritizes visual working memory representations that serve consecutive tasks. Observers remembered two targets for a sequence of two visual search tasks, thus making one target currently relevant, and the other prospectively relevant. We show that during the retention interval prior to the first search, lateralized parieto-occipital EEG alpha (8–14 Hz) suppression is stronger for current compared with prospective search targets. Crucially, between the first and second search task, this difference in posterior alpha lateralization reverses, reflecting the change in priority states of the two target representations. Connectivity analyses indicate that this switch in posterior alpha lateralization is driven by frontal delta/low-theta (2–6 Hz) activity. Moreover, this frontal low-frequency signal also predicts task performance after the switch. We thus obtained evidence for large-scale network interactions underlying the flexible shifting between the priority states of multiple memory representations in VWM.

Posterior alpha and frontal delta oscillations interactively support priority switches within visual working memory.

Visual search is assumed to be guided by an active visual working memory representation of what we are currently looking for. This attentional template can be dissociated from accessory memory representations that are only needed prospectively, for a future task, and that until then should be prevented from guiding attention. Little is known about how the brain sequentially prioritizes, and switches between memory representations for successive task goals. We measured EEG while human observers performed two consecutive working memory-guided visual search tasks. Prior to the first search task, a cue instructed observers which item to look for first (current template), and which second (prospective template). During the first delay, leading up to the first of the two searches, posterior alpha power (8-14 Hz) was more suppressed contralateral to the memory item. These lateralized alpha dynamics were stronger if the lateralized item was the imminent search target (current template), than when it was the subsequent search target (prospective template). To investigate the electrophysiological mechanisms underlying the switch in priority, on 40% of the trials an auditory cue replaced the first search, telling observers that at this point the first template could be dropped, in favor of now prioritizing the second, prospective template. Dropping the first template resulted in clear alpha enhancement, while turning the former prospective template into the current search target resulted in alpha suppression. Furthermore, this switch in posterior alpha lateralization was predicted by an increase in frontal delta/low theta (2–6 Hz) power. This increase in low-frequency power in frontal regions also predicted faster response times on the second search task. We thus obtained evidence for large-scale network interactions during the flexible "juggling" between priority states of multiple memory items in between search tasks. Meeting abstract presented at VSS 2018

Relationships between alpha oscillations during speech preparation and the listener N400 ERP to the produced speech

While previous studies separately demonstrate EEG spectral modulations during speech preparation and ERP responses to the listened speech, it is unclear whether these responses are related on a trial-by-trial basis between a speaker and listener. In order to determine whether these responses are related in real-time, Electroencephalography (EEG) responses were measured simultaneously within a speaker and listener using a 24 electrode Mobile EEG system (18 participants; 9 pairs) during a sentence completion task. Each trial consisted of a sentence prompt with an incomplete ending (e.g. “I took my dog for a ____”). The speaker was instructed to fill in the ending with something expected (e.g. “walk”) (40 trials) or unexpected (e.g. “drink”) (40 trials). The other participant listened to the speaker throughout the block. We found that lower alpha band activity was reduced when individuals prepared unexpected sentence endings compared to expected sentence endings. Greater reductions in the speaker’s lower alpha activity during response preparation were correlated with a more negative N400 response in the listener to the unexpected word. These findings demonstrate that alpha suppression and the N400 ERP effect are present within a hyperscanning context and they are correlated between the speaker and listener during sentence completion.

Child brain exhibits a multi-rhythmic response to attachment cues.

Research on the human parental brain implicated brain networks involved in simulation, mentalization and emotion processing and indicated that stimuli of own parent–child interaction elicit greater integration among networks supporting attachment. Here, we examined children’s neural activation while viewing own parent–child interactions and asked whether similar networks activate when children are exposed to attachment stimuli. Sixty-five 11-year-old children underwent magnetoencephalography (MEG) while observing own vs unfamiliar mother-child interaction. Own mother–child interactions elicited a greater neural response across distributed brain areas including alpha suppression in posterior regions, theta enhancement in the fusiform gyrus and beta- and gamma-band oscillations across a wide cluster in the right temporal cortex, comprising the superior temporal sulcus/superior temporal gyrus and insula. Theta and gamma activations were associated with the degree of mother–child social synchrony in the home ecology. Findings from this exploratory study are the first to show activations in children that are similar to previous findings in parents and comparable associations between social synchrony and gamma oscillations in temporal regions. Results indicate that attachment stimuli elicit a strong neural response in children that spreads across a wide range of oscillations, underscoring the considerable neural resources allocated to this fundamental, survival-related cue.

Suppression of Sensorimotor Alpha Power Associated With Pain Expressed by an Avatar: A Preliminary EEG Study.

Several studies using functional magnetic resonance imaging (fMRI) showed that empathic capabilities are associated with the activation (and deactivation) of relatively specific neural circuits. A growing number of electroencephalography studies also suggest that it might be useful to assess empathy. The main goal of this study was to use quantitative electroencephalography (qEEG) to test whether observation of pain expressed by an avatar (virtual reality) induces a suppression of alpha waves over sensorimotor cortical areas, as it is observed with human stimuli. Not only was it the case, but also the magnitude of alpha suppression was correlated with perspective-taking capacity of participants. Both empathy levels and magnitude of sensorimotor alpha suppression (SAS) were significantly higher in women than men. Interestingly, a significant interaction emerged between levels of individual empathy and specificity of experimental instructions, where SAS in participants with good perspective-taking was higher during passive observation of the distressed avatar, while the opposite was true during an active (trying to understand) condition. These results suggest that: (1) synthetic characters are able to elicit SAS; (2) SAS is indeed associated with perspective-taking capacities; (3) Persons with poorer perspective-taking capacities can show significant SAS when proper instructions are provided. Therefore, qEEG represents a low-cost objective approach to measure perspective-taking abilities.

Error, rather than its probability, elicits specific electrocortical signatures: a combined EEG-immersive virtual reality study of action observation.

Detecting errors in one's own actions, and in the actions of others, is a crucial ability for adaptable and flexible behavior. Studies show that specific EEG signatures underpin the monitoring of observed erroneous actions (error-related negativity, error positivity, mid-frontal theta oscillations). However, the majority of studies on action observation used sequences of trials where erroneous actions were less frequent than correct actions. Therefore, it was not possible to disentangle whether the activation of the performance monitoring system was due to an error, as a violation of the intended goal, or to a surprise/novelty effect, associated with a rare and unexpected event. Combining EEG and immersive virtual reality (IVR-CAVE system), we recorded the neural signal of 25 young adults who observed, in first-person perspective, simple reach-to-grasp actions performed by an avatar aiming for a glass. Importantly, the proportion of erroneous actions was higher than correct actions. Results showed that the observation of erroneous actions elicits the typical electrocortical signatures of error monitoring, and therefore the violation of the action goal is still perceived as a salient event. The observation of correct actions elicited stronger alpha suppression. This confirmed the role of the alpha-frequency band in the general orienting response to novel and infrequent stimuli. Our data provide novel evidence that an observed goal error (the action slip) triggers the activity of the performance-monitoring system even when erroneous actions, which are, typically, relevant events, occur more often than correct actions and thus are not salient because of their rarity. NEW & NOTEWORTHY Activation of the performance-monitoring system (PMS) is typically investigated when errors in a sequence are comparatively rare. However, whether the PMS is activated by errors per se or by their infrequency is not known. Combining EEG-virtual reality techniques, we found that observing frequent (70%) action errors performed by avatars elicits electrocortical error signatures suggesting that deviation from the prediction of how learned actions should correctly deploy, rather than its frequency, is coded in the PMS.

Brain Electrodynamic and Hemodynamic Signatures Against Fatigue During Driving.

Fatigue is likely to be gradually cumulated in a prolonged and attention-demanding task that may adversely affect task performance. To address the brain dynamics during a driving task, this study recruited 16 subjects to participate in an event-related lane-departure driving experiment. Each subject was instructed to maintain attention and task performance throughout an hour-long driving experiment. The subjects' brain electrodynamics and hemodynamics were simultaneously recorded via 32-channel electroencephalography (EEG) and 8-source/16-detector functional near-infrared spectroscopy (fNIRS). The behavior performance demonstrated that all subjects were able to promptly respond to lane-deviation events, even if the sign of fatigue arose in the brain, which suggests that the subjects were fighting fatigue during the driving experiment. The EEG event-related analysis showed strengthening alpha suppression in the occipital cortex, a common brain region of fatigue. Furthermore, we noted increasing oxygenated hemoglobin (HbO) of the brain to fight driving fatigue in the frontal cortex, primary motor cortex, parieto-occipital cortex and supplementary motor area. In conclusion, the increasing neural activity and cortical activations were aimed at maintaining driving performance when fatigue emerged. The electrodynamic and hemodynamic signatures of fatigue fighting contribute to our understanding of the brain dynamics of driving fatigue and address driving safety issues through the maintenance of attention and behavioral performance.

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

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

Alpha suppression over parietal electrode sites predicts decisions to trust

ABSTRACTDecisions to trust help form the basis of relationships and society yet little is known about their neurophysiology. We told participants they were playing a coin toss game with a trustworthy and an untrustworthy person and measured their neural activity with EEG as they decided whether to trust those fictitious interaction partners. Target people ostensibly correctly reported the outcome of a coin toss on 66% of trials. Behaviorally, participants probability matched and chose to trust the reported coin flips from each profile equally by the end of 100 trials. Electrophysiologically, there were reliable differences in the pattern of oscillatory activity in the alpha band (8-13Hz) over parietal electrode sites 1–3 s prior to their trust decisions. Specifically, for trustworthy profiles, there was greater alpha suppression for trust decisions vs. distrust decisions. Conversely, for untrustworthy profiles there was greater alpha suppression for distrust decisions vs. trust decisions. This differential activity (trust minus distrust) also predicted the number of trust decisions made. Our results indicate that the intentions to trust people form very early in the processing stream and manifest as alpha suppression over parietal cortex.

Oscillatory rhythm of reward: anticipation and processing of rewards in children with and without autism

BackgroundAutism spectrum disorder (ASD) is a complex neurodevelopmental condition, and multiple theories have emerged concerning core social deficits. While the social motivation hypothesis proposes that deficits in the social reward system cause individuals with ASD to engage less in social interaction, the overly intense world hypothesis (sensory over-responsivity) proposes that individuals with ASD find stimuli to be too intense and may have hypersensitivity to social interaction, leading them to avoid these interactions.MethodsEEG was recorded during reward anticipation and reward processing. Reward anticipation was measured using alpha asymmetry, and post-feedback theta was utilized to measure reward processing. Additionally, we calculated post-feedback alpha suppression to measure attention and salience. Participants were 6- to 8-year-olds with (N = 20) and without (N = 23) ASD.ResultsChildren with ASD showed more left-dominant alpha suppression when anticipating rewards accompanied by nonsocial stimuli compared to social stimuli. During reward processing, children with ASD had less theta activity than typically developing (TD) children. Alpha activity after feedback showed the opposite pattern: children with ASD had greater alpha suppression than TD children. Significant correlations were observed between behavioral measures of autism severity and EEG activity in both the reward anticipation and reward processing time periods.ConclusionsThe findings provide evidence that children with ASD have greater approach motivation prior to nonsocial (compared to social) stimuli. Results after feedback suggest that children with ASD evidence less robust activity thought to reflect evaluation and processing of rewards (e.g., theta) compared to TD children. However, children with ASD evidence greater alpha suppression after feedback compared to TD children. We hypothesize that post-feedback alpha suppression reflects general cognitive engagement—which suggests that children with ASD may experience feedback as overly intense. Taken together, these results suggest that aspects of both the social motivation hypothesis and the overly intense world hypothesis may be occurring simultaneously.