Event-related Spectral Perturbation Research Articles

Electrophysiological Correlates of Social Decision-making: An EEG Investigation of a Modified Ultimatum Game.

Cooperation behaviors during social decision-making have been shown to be sensitive to manipulations of context. However, it remains unclear how aspects of context in dynamic social interactions, such as observed nonverbal behaviors, may modulate cooperation decisions and the associated neural mechanisms. In this study, participants responded to offers from proposers to split $10 in an Ultimatum Game following observation of proposer approach (friendly) or avoidance (nonfriendly) behaviors, displayed by dynamic whole-body animated avatars, or following a nonsocial interaction control condition. As expected, behavioral results showed that participants tended to have greater acceptance rates for unfair offers following observed nonverbal social interactions with proposers compared with control, suggesting an enhancing effect of social interactions on cooperative decisions. ERP results showed greater N1 and N2 responses at the beginning of social interaction conditions compared with control, and greater sustained and late positivity responses for observed approach and avoidance proposer behaviors compared with control. Event-related spectral perturbation (ERSP) results showed differential sensitivity within theta, alpha, and beta bands during observation of social interactions and offers that was associated with subsequent decision behaviors. Together, these results point to the impact of proposers' nonverbal behaviors on subsequent cooperation decisions at both behavioral and neural levels. The ERP and ERSP findings suggest modulated attention, monitoring, and processing of biological motion during the observed nonverbal social interactions, influencing the participants' responses to offers. These findings shed light on electrophysiological correlates of response to observed social interactions that predict subsequent social decisions.

Event related delta and theta oscillations are reduced in severe obstructive sleep apnea as a possible electrophysiologial evidence of subtle cognitive changes

AbstractBackgroundObstructive Sleep Apnea Syndrome (OSAS) is a common sleep disorder that leads to widespread cognitive impairment when left untreated. OSAS is also reported as a risk factor for developing Alzheimer’s disease. Recent studies report a shared pathophysiology between OSAS and Alzheimer’s disease (Polsek et al., 2018; Baril et al., 2018). Working memory and attention related ERP P300 deficits were previously reported (for a review see, Raggi and Ferri, 2012). This study aims to investigate electrophysiological changes by using time‐frequency analysis to gain a better understanding on cognitive impairment in OSAS.Method56 severe OSAS patients and age, education and gender matched 33 healthy controls were participated to the study. Participants completed a classical auditory oddball task. A complex Morlet with Gabor normalization was applied and total power within four frequency bandwidths, delta (0.5‐3.5 Hz), theta (4‐7 Hz), alpha (8‐13 Hz), and beta (15‐30 Hz), was calculated using Event‐Related Spectral Perturbation (ERSP) analyses.ResultOSAS patients had reduced delta and theta ERPS to target stimuli compared to healthy controls in repeated measures ANOVA yielding a significant main GROUP effect (respectively, [F(1,87)=9.181, p=0.003] and [F(1,87)=5.083, p=0.027]). No differences were found on alpha and beta power.ConclusionWe found reduced delta and theta activity in severe OSAS patients. Delta EROs activity is associated with attention and decision making (Başar ve Stampfer, 1985; Stampfer ve Başar, 1985), whereas theta activity was associated with task induced activation of working memory (Yordanova et al. 2000). Reduced delta and theta EROs activity can be useful indices of subtle cognitive impairment in severe OSAS even before neuropsychological test. These results strengthen our understanding of the cognitive changes in OSAS by means of electrophysiological methodologies. This study was supported by Dokuz Eylul University Scientific Research Projects (Project Number: 2014.KB.SAG.058).

Improving the multi‐class classification of Alzheimer’s disease with machine learning‐based techniques: An EEG‐fNIRS hybridization study

AbstractBackgroundAs an incurable neurodegenerative disorder, Alzheimer’s Disease (AD) is being projected to become one of the most expensive diseases for understanding the pathophysiological mechanism. Exploring alterations in the AD brain network is therefore of central importance for early and accurate diagnosis of cognitive deficits levels, yet diagnostic uncertainties exist merely confirmed by postmortem brain examination. The hybrid approach of two modalities, Electroencephalography (EEG) and functional Near‐Infrared Spectroscopy (fNIRS) reveals an ideal technique‐derived diagnosis due to the inexpensive and noninvasive experiments coupled with the reliability and versatility that make it highly desirable for AD multi‐class classification tasks.MethodsIn this study, the hybrid EEG‐fNIRS was employed in constructing the classification machine learning (ML)‐based models to categorize four subject groups, including healthy controls (HC) and three AD patient classes. First, a concurrent EEG‐fNIRS setup was utilized to record data from 41 subjects during the Oddball – a cognitive ability test and 1‐back – a memory ability test. Second, while fNIRS features were computed and extracted, the event‐related spectral perturbation (ERSP) features measuring the average dynamic changes in amplitude of three main EEG frequency bands were extracted. Third, a conventional neural network and a hybrid deep Convolutional Neural Network (CNN) ‐ Long Short‐Term Memory Network (LSTM) was built for the multi‐class classification using the fNIRS and EEG features, respectively. To boost the classification accuracy, the output of different models was combined by majority voting methods.ResultsThe hybrid EEG‐fNIRS feature set was able to achieve a higher accuracy (71.01% ± 0.004) by combing their complementary properties, compared to using EEG (66.35% ± 0.016) or fNIRS (67.15% ± 0.017) alone. In addition, fNIRS and ERSP feature patterns displayed a significant difference between subject groups during the Oddball and 1‐back experimental tasks. Thus, the feature‐level ensemble shows a great ability to understand neurophysiological AD status and its related symptoms and develop a syndrome‐specific diagnostic tool for our future works.ConclusionsThese findings demonstrate the potential of the hybrid EEG‐fNIRS systems to enhance the AD diagnosis and assessment process and the capability of ML techniques to facilitate further AD classification studies.

Irrelevant Robot Signals in a Categorization Task Induce Cognitive Conflict in Performance, Eye Trajectories, the N2 Component of the EEG Signal, and Frontal Theta Oscillations.

Understanding others' nonverbal behavior is essential for social interaction, as it allows, among others, to infer mental states. Although gaze communication, a well-established nonverbal social behavior, has shown its importance in inferring others' mental states, not much is known about the effects of irrelevant gaze signals on cognitive conflict markers during collaborative settings. In the present study, participants completed a categorization task where they categorized objects based on their color while observing images of a robot. On each trial, participants observed the robot iCub grasping an object from a table and offering it to them to simulate a handover. Once the robot "moved" the object forward, participants were asked to categorize the object according to its color. Before participants were allowed to respond, the robot made a lateral head/gaze shift. The gaze shifts were either congruent or incongruent with the object's color. We expected that incongruent head cues would induce more errors (Study 1), would be associated with more curvature in eye-tracking trajectories (Study 2), and induce larger amplitude in electrophysiological markers of cognitive conflict (Study 3). Results of the three studies show more oculomotor interference as measured in error rates (Study 1), larger curvatures eye-tracking trajectories (Study 2), and higher amplitudes of the N2 ERP component of the EEG signals as well as higher event-related spectral perturbation amplitudes (Study 3) for incongruent trials compared with congruent trials. Our findings reveal that behavioral, ocular, and electrophysiological markers can index the influence of irrelevant signals during goal-oriented tasks.

Investigation of the interaction between emotion and working memory load using spatiotemporal pattern similarity analysis

Objective. Accumulating evidence has revealed that emotions can be provided with the modulatory effect on working memory (WM) and WM load is an important factor for the interaction between emotion and WM. However, it remains controversial whether emotions inhibit or facilitate WM and the interaction between cognitive task, processing load and emotional processing remains unclear. Approach. In this study, we used a change detection paradigm wherein memory items have four different load sizes and emotion videos to induce three emotions (negative, neutral, and positive). We performed an event-related spectral perturbation (ERSP) analysis and a spatiotemporal pattern similarity (STPS) analysis on the electroencephalography data. Main results. The ERSP results indicated that alpha and beta oscillations can reflect the difference among WM load sizes and also can reflect the difference among emotions under middle high WM load over posterior brain region in the maintenance stage. Moreover, the STPS results demonstrated a significant interaction between emotion and WM load size in the posterior region and found significantly higher similarity indexes for the negative emotion to the neutral emotion under the middle high WM load during WM maintenance. In addition, The STPS results also revealed that both positive emotion and negative emotion could interfere with the distinction of load sizes. Significance. The consistence of the behavioral, ERSP and STPS results suggested that when the memory load approaches the limit of WM capacity, negative emotion could facilitate WM through the top–down attention modulation promoting the most relevant information storage during WM maintenance.

Distractor filtering and its electrophysiological correlates in schizophrenia

ObjectivePatients with schizophrenia are characterized by compromised working memory (WM) performance and increased distractibility. Theta synchronization (especially over the frontal midline areas) is related to cognitive control and executive processes during WM encoding and retention. Alpha event-related desynchronization (ERD) is associated with information processing and attention. MethodsParticipants (35 patients and 39 matched controls) performed a modified Sternberg WM task, containing salient and non-salient distractor items in the retention period. A high-density 128 channel EEG was recorded during the task. Theta (4–7 Hz) and fast alpha (10–13 Hz) event-related spectral perturbation (ERSP) were analyzed during the retention and encoding period. ResultsPatients with schizophrenia showed worse WM performance and increased attentional distractibility in terms of lower hit rates and increased distractor-related commission errors compared to healthy controls. Theta synchronization was modulated by condition (learning vs. distractor) in both groups but it was modulated by salience only in controls. Furthermore, salience of distractors modulated less the fast alpha ERD in patients. ConclusionsOur results suggest that patients with schizophrenia process salient and non-salient distracting information less efficiently and show weaker cognitive control compared to controls. SignificanceThese differences may partly account for diminished WM performance and increased distractibility in schizophrenia.

Mu rhythm dynamics suggest automatic activation of motor and premotor brain regions during speech processing

Results are mixed regarding the question of whether listening to speech activates automatic speech specific neural processes, or whether such activity is due to general cognitive mechanisms such as attention and memory. We suggest that analyzing the dynamics of mu rhythms over the course of a trial using event-related spectral perturbations (ERSPs) is useful for disentangling the competing hypotheses. Our findings suggest that there is automatic activation of motor and premotor areas of the brain that occurs while passively listening to speech, and that this activation is not present while listening to noise. Moreover, this activation is more strongly present in the low alpha frequencies, which are associated with attention, when participants engage in active discrimination of stimuli, and late in the trial prior to a button press.

Validating Poly(3,4-ethylene dioxythiophene) Polystyrene Sulfonate-Based Textile Electroencephalography Electrodes by a Textile-Based Head Phantom.

It is important to go through a validation process when developing new electroencephalography (EEG) electrodes, but it is impossible to keep the human mind constant, making the process difficult. It is also very difficult to identify noise and signals as the input signal is unknown. In this work, we have validated textile-based EEG electrodes constructed from a poly(3,4-ethylene dioxythiophene) polystyrene sulfonate:/polydimethylsiloxane coated cotton fabric using a textile-based head phantom. The performance of the textile-based electrode has also been compared against a commercial dry electrode. The textile electrodes collected a signal to a smaller skin-to-electrode impedance (−18.9%) and a higher signal-to-noise ratio (+3.45%) than Ag/AgCl dry electrodes. From an EEGLAB, it was observed that the inter-trial coherence and event-related spectral perturbation graphs of the textile-based electrodes were identical to the Ag/AgCl electrodes. Thus, these textile-based electrodes can be a potential alternative to monitor brain activity.

Interhemispheric differences in time-frequency representation of motor evoked potentials in brain tumor patients

ObjectiveConventional time-series parameters are unreliable descriptors of motor-evoked potentials (MEPs) in brain tumor patients. Frequency domain analysis is suggested to provide additional information about the status of the cortico-spinal motor system. Aim of the present study was to describe the time-frequency representation of MEPs and its relation to the motor performance. MethodsThis study enrolled 17 consecutive brain tumor patients with impaired dexterity. After brain mapping of the affected (AH) and non-affected (NAH) hemisphere, TMS was applied to the hotspots of the abductor pollicis brevis muscles (APB). Using a Morlet wavelet approach, event-related spectral perturbation (ERSP) and inter-trial coherence (ITC) of the MEPs were calculated and compared to the Grooved Pegboard Test (GPT). Additionally, inter- and intra-subject reliability was assessed by the intraclass correlation coefficient (ICC). ResultsMEPs were projecting to a frequency band between 30 and 400 Hz with a local maximum between 100 and 150 Hz. There was a significant ERSP and ITC reduction of the AH in comparison to the NAH. In contrast, no interhemispheric differences were depicted in the conventional time-series analysis. ERSP and ITC values correlated significantly with GPT results (r = 0.35 and r = 0.50). Time-frequency MEP description had good inter-and intra-subject reliability (ICC = 0.63). ConclusionsBrain tumors affect corticospinal transmission resulting in a reduction of temporal and spectral MEP synchronization correlating with the dexterity performance. SignificanceTime-frequency representation of MEPs provide additional information beyond conventional time-domain features.

Spinal and Cerebral Integration of Noxious Inputs in Left-handed Individuals.

Some pain-related information is processed preferentially in the right cerebral hemisphere. Considering that functional lateralization can be affected by handedness, spinal and cerebral pain-related responses may be different between right- and left-handed individuals. Therefore, this study aimed to investigate the cortical and spinal mechanisms of nociceptive integration when nociceptive stimuli are applied to right -handed vs. left -handed individuals. The NFR, evoked potentials (ERP: P45, N100, P260), and event-related spectral perturbations (ERSP: theta, alpha, beta and gamma band oscillations) were compared between ten right-handed and ten left-handed participants. Pain was induced by transcutaneous electrical stimulation of the lower limbs and left upper limb. Stimulation intensity was adjusted individually in five counterbalanced conditions of 21 stimuli each: three unilateral (right lower limb, left lower limb, and left upper limb stimulation) and two bilateral conditions (right and left lower limbs, and the right lower limb and left upper limb stimulation). The amplitude of the NFR, ERP, ERSP, and pain ratings were compared between groups and conditions using a mixed ANOVA. A significant increase of responses was observed in bilateral compared with unilateral conditions for pain intensity, NFR amplitude, N100, theta oscillations, and gamma oscillations. However, these effects were not significantly different between right- and left-handed individuals. These results suggest that spinal and cerebral integration of bilateral nociceptive inputs is similar between right- and left-handed individuals. They also imply that pain-related responses measured in this study may be examined independently of handedness.

Temporal and time-frequency features of auditory oddball response in distinct subtypes of patients at clinical high risk for psychosis.

Individuals at clinical high risk (CHR) for psychosis exhibit a reduced P300 oddball response, which indicates deficits in attention and working memory processes. Previous studies have mainly researched these responses in the temporal domain; hence, non-phase-locked or induced neural activities may have been ignored. Event-related potential (ERP) and time-frequency (TF) information, combined with clinical and cognitive profiles, may provide an insight into the pathophysiology and psychopathology of the CHR stage. The 104 CHR individuals who completed cognitive assessments and ERP tests were recruited and followed up between 2016 and 2018. Individuals with CHR were classified by three clinical subtypes demonstrated before, specifically 32 from Cluster-1 (characterized by extensive negative symptoms and cognitive deficits, at the highest risk for conversion to psychosis), 34 from Cluster-2 (characterized by thought and behavioral disorganization, with moderate cognitive impairment), and 38 from Cluster-3 (characterized by the mildest symptoms and cognitive deficits). Electroencephalograms were recorded during the auditory oddball paradigm. The P300 ERPs were analyzed in the temporal domain. The event-related spectral perturbation (ERSP) and inter-trial coherence (ITC) were acquired by TF analysis. A reduced P300 response to target tones was noted in Cluster-1 relative to the other two clusters. Moreover, the P300 amplitude of Cluster-1 was associated with speed of processing (SoP) scores. Furthermore, the P300 amplitude of Cluster-3 was significantly correlated with verbal and visual learning scores. In the TF analysis, decreased delta ERSP and ITC were observed in Cluster-1; delta ITC was associated with SoP scores in Cluster-3. The results indicate relatively disrupted oddball responses in a certain CHR subtype and a close affinity between these electrophysiological indexes and attention, working memory, and declarative memory within different CHR clusters. These findings suggest that the auditory oddball response is a potential neurophysiological marker for distinct clinical subtypes of CHR.

Neural Dynamics of Target Detection via Wireless EEG in Embodied Cognition.

Embodied cognitive attention detection is important for many real-world applications, such as monitoring attention in daily driving and studying. Exploring how the brain and behavior are influenced by visual sensory inputs becomes a major challenge in the real world. The neural activity of embodied mind cognitive states can be understood through simple symbol experimental design. However, searching for a particular target in the real world is more complicated than during a simple symbol experiment in the laboratory setting. Hence, the development of realistic situations for investigating the neural dynamics of subjects during real-world environments is critical. This study designed a novel military-inspired target detection task for investigating the neural activities of performing embodied cognition tasks in the real-world setting. We adopted independent component analysis (ICA) and electroencephalogram (EEG) dipole source localization methods to study the participant’s event-related potentials (ERPs), event-related spectral perturbation (ERSP), and power spectral density (PSD) during the target detection task using a wireless EEG system, which is more convenient for real-life use. Behavioral results showed that the response time in the congruent condition (582 ms) was shorter than those in the incongruent (666 ms) and nontarget (863 ms) conditions. Regarding the EEG observation, we observed N200-P300 wave activation in the middle occipital lobe and P300-N500 wave activation in the right frontal lobe and left motor cortex, which are associated with attention ERPs. Furthermore, delta (1–4 Hz) and theta (4–7 Hz) band powers in the right frontal lobe, as well as alpha (8–12 Hz) and beta (13–30 Hz) band powers in the left motor cortex were suppressed, whereas the theta (4–7 Hz) band powers in the middle occipital lobe were increased considerably in the attention task. Experimental results showed that the embodied body function influences human mental states and psychological performance under cognition attention tasks. These neural markers will be also feasible to implement in the real-time brain computer interface. Novel findings in this study can be helpful for humans to further understand the interaction between the brain and behavior in multiple target detection conditions in real life.

Cortical interaction of bilateral inputs is similar for noxious and innocuous stimuli but leads to different perceptual effects.

The cerebral integration of somatosensory inputs from multiple sources is essential to produce adapted behaviors. Previous studies suggest that bilateral somatosensory inputs interact differently depending on stimulus characteristics, including their noxious nature. The aim of this study was to clarify how bilateral inputs evoked by noxious laser stimuli, noxious shocks, and innocuous shocks interact in terms of perception and brain responses. The experiment comprised two conditions (right-hand stimulation and concurrent stimulation of both hands) in which painful laser stimuli, painful shocks and non-painful shocks were delivered. Perception, somatosensory-evoked potentials (P45, N100, P260), laser-evoked potentials (N1, N2 and P2) and event-related spectral perturbations (delta to gamma oscillation power) were compared between conditions and stimulus modalities. The amplitude of negative vertex potentials (N2 or N100) and the power of delta/theta oscillations were increased in the bilateral compared with unilateral condition, regardless of the stimulus type (P < 0.01). However, gamma oscillation power increased for painful and non-painful shocks (P < 0.01), but not for painful laser stimuli (P = 0.08). Despite the similarities in terms of brain activity, bilateral inputs interacted differently for painful stimuli, for which perception remained unchanged, and non-painful stimuli, for which perception increased. This may reflect a ceiling effect for the attentional capture by noxious stimuli and warrants further investigations to examine the regulation of such interactions by bottom-up and top-down processes.

Neural Mechanism of Repeated Transcranial Magnetic Stimulation to Enhance Visual Working Memory in Elderly Individuals With Subjective Cognitive Decline.

Visual working memory (VWM), the core process inherent to many advanced cognitive processes, deteriorates with age. Elderly individuals usually experience defects in the processing of VWM. The dorsolateral prefrontal cortex is a key structure for the top-down control of working memory processes. Many studies have shown that repeated transcranial magnetic stimulation (rTMS) improves VWM by modulating the excitability of neurons in the target cortical region, though the underlying neural mechanism has not been clarified. Therefore, this study sought to assess the characteristics of brain memory function post-rTMS targeting the left dorsolateral prefrontal cortex. The study stimulated the left dorsolateral prefrontal cortex in elderly individuals by performing a high-frequency rTMS protocol and evaluated behavioral performance using cognitive tasks and a VWM task. Based on the simultaneously recorded electroencephalogram signals, event-related potential and event-related spectral perturbation analysis techniques were used to investigate the variation characteristics of event-related potential components' (N2PC and CDA) amplitudes and neural oscillations in elderly individuals to elucidate the effect of high-frequency rTMS. The results found that rTMS enhanced VWM performance and significantly improved attention and executive function in elderly individuals with subjective cognitive decline. We therefore speculate that rTMS enhances VWM by increasing the N2PC and CDA amplitude, alongside increasing β oscillation activity. This would improve the attention and allocation of resources in elderly individuals such as to improve an individual's VWM.

Electrophysiological aftereffects of high-frequency transcranial random noise stimulation (hf-tRNS): an EEG investigation

There is evidence that high-frequency transcranial random noise stimulation (hf-tRNS) is effective in improving behavioural performance in several visual tasks. However, so far there has been limited research into the spatial and temporal characteristics of hf-tRNS-induced facilitatory effects. In the present study, electroencephalogram (EEG) was used to investigate the spatial and temporal dynamics of cortical activity modulated by offline hf-tRNS on performance on a motion direction discrimination task. We used EEG to measure the amplitude of motion-related VEPs over the parieto-occipital cortex, as well as oscillatory power spectral density (PSD) at rest. A time–frequency decomposition analysis was also performed to investigate the shift in event-related spectral perturbation (ERSP) in response to the motion stimuli between the pre- and post-stimulation period. The results showed that the accuracy of the motion direction discrimination task was not modulated by offline hf-tRNS. Although the motion task was able to elicit motion-dependent VEP components (P1, N2, and P2), none of them showed any significant change between pre- and post-stimulation. We also found a time-dependent increase of the PSD in alpha and beta bands regardless of the stimulation protocol. Finally, time–frequency analysis showed a modulation of ERSP power in the hf-tRNS condition for gamma activity when compared to pre-stimulation periods and Sham stimulation. Overall, these results show that offline hf-tRNS may induce moderate aftereffects in brain oscillatory activity.

Spectral features of cortical auditory evoked potentials inform hearing threshold and intensity percepts in acoustic and electric hearing

Objective. Stimulus-elicited changes in electroencephalography (EEG) recordings can be represented using Fourier magnitude and phase features (Makeig et al (2004 Trends Cogn. Sci. 8 204–10)). The present study aimed to quantify how much information about hearing responses are contained in the magnitude, quantified by event-related spectral perturbations (ERSPs); and the phase, quantified by inter-trial coherence (ITC). By testing if one feature contained more information and whether this information was mutually exclusive to the features, we aimed to relate specific EEG magnitude and phase features to hearing perception. Approach. EEG responses were recorded from 20 adults who were presented with acoustic stimuli, and 20 adult cochlear implant users with electrical stimuli. Both groups were presented with short, 50 ms stimuli at varying intensity levels relative to their hearing thresholds. Extracted ERSP and ITC features were inputs for a linear discriminant analysis classifier (Wong et al (2016 J. Neural. Eng. 13 036003)). The classifier then predicted whether the EEG signal contained information about the sound stimuli based on the input features. Classifier decoding accuracy was quantified with the mutual information measure (Cottaris and Elfar (2009 J. Neural. Eng. 6 026007), Hawellek et al (2016 Proc. Natl Acad. Sci. 113 13492–7)), and compared across the two feature sets, and to when both feature sets were combined. Main results. We found that classifiers using either ITC or ERSP feature sets were both able to decode hearing perception, but ITC-feature classifiers were able to decode responses to a lower but still audible stimulation intensity, making ITC more useful than ERSP for hearing threshold estimation. We also found that combining the information from both feature sets did not improve decoding significantly, implying that ERSP brain dynamics has a limited contribution to the EEG response, possibly due to the stimuli used in this study. Significance. We successfully related hearing perception to an EEG measure, which does not require behavioral feedback from the listener; an objective measure is important in both neuroscience research and clinical audiology.

Trait sensation seeking is associated with heightened beta-band oscillatory dynamics over left ventrolateral prefrontal cortex during reward expectancy

BackgroundSensation Seeking, the proclivity toward novel and stimulating experiences, is associated with greater left ventrolateral prefrontal cortex (vlPFC) activity during uncertain reward expectancy. Here, we examined relationships between sensation seeking and vlPFC oscillatory dynamics using electroencephalography (EEG). MethodsIn 26 adolescents/young adults (16 female; 22.3 ± 1.7yrs), EEG was measured during uncertain reward expectancy. Event-related spectral perturbations (ERSP) from 15-80 Hz (beta/gamma bands) were compared as a function of uncertain reward expected value and assessed for relationships with feedback-related negativity (FRN) response to outcome feedback and response tendency measures of risk for BD. ResultsEvent-related synchronization (ERS) between 15-25 Hz (beta) over left vlPFC was sensitive to the expected value of uncertain reward (rho=0.46; p = 0.048), and correlated with sensation seeking (r = 0.49, p < 0.01) and feedback-related negativity (FRN), where greater beta ERS was related to larger FRN (r = -0.39, p = 0.047). FRN was also related to behavioral inhibition (r = 0.49, p < 0.01). LimitationsIt is unknown whether results may extrapolate to clinical populations, given the healthy sample used here. Further, although we have confidence that the beta-band signal we measure in this study arises from left prefrontal cortex, we largely infer a left vlPFC source. ConclusionsThese findings highlight the role of left vlPFC in evaluation of immediate rewards. We now provide a link between reward expectancy-related left vlPFC activity and the well-characterized FRN, with a known role in attentive processing. These findings can guide treatment development for mania/hypomania at-risk individuals, including transcranial alternating current stimulation.

Long-Lasting Event-Related Beta Synchronizations of Electroencephalographic Activity in Response to Support-Surface Perturbations During Upright Stance: A Pilot Study Associating Beta Rebound and Active Monitoring in the Intermittent Postural Control.

Movement related beta band cortical oscillations, including beta rebound after execution and/or suppression of movement, have drawn attention in upper extremity motor control literature. However, fewer studies focused on beta band oscillations during postural control in upright stance. In this preliminary study, we examined beta rebound and other components of electroencephalogram (EEG) activity during perturbed upright stance to investigate supraspinal contributions to postural stabilization. Particularly, we aimed to clarify the timing and duration of beta rebound within a non-sustained, but long-lasting postural recovery process that occurs more slowly compared to upper extremities. To this end, EEG signals were acquired from nine healthy young adults in response to a brief support-surface perturbation, together with the center of pressure, the center of mass and electromyogram (EMG) activities of ankle muscles. Event-related potentials (ERPs) and event-related spectral perturbations were computed from EEG data using the perturbation-onset as a triggering event. After short-latency (<0.3 s) ERPs, our results showed a decrease in high-beta band oscillations (event-related desynchronization), which was followed by a significant increase (event-related synchronization) in the same band, as well as a decrease in theta band oscillations. Unlike during upper extremity motor tasks, the beta rebound in this case was initiated before the postural recovery was completed, and sustained for as long as 3 s with small EMG responses for the first half period, followed by no excessive EMG activities for the second half period. We speculate that those novel characteristics of beta rebound might be caused by slow postural dynamics along a stable manifold of the unstable saddle-type upright equilibrium of the postural control system without active feedback control, but with active monitoring of the postural state, in the framework of the intermittent control.

Intermittent Theta Burst Stimulation (iTBS) as an Optimal Treatment for Schizophrenia Risk Decision: an ERSP Study.

Objective: People with schizophrenia have serious impairments in social function, especially in decision-making ability. Transcranial magnetic stimulation modified intermittent theta burst transcranial magnetic stimulation (iTBS) has been shown to regulate the functional connection of brain networks. Our study explored the therapeutic effect of iTBS on decision-making disorders in schizophrenia.Methods: Participants were pseudorandomized and assigned to iTBS (n = 16) or sham (n = 16) group. iTBS group was administered 1,800 pulses on the target of the left dorsol lateral prefrontal cortex (L-DLPFC) per day for 14 consecutive days. We compared Iowa gambling task performance and associated event-related spectral perturbation results (ERSP) among two groups.Results: The results show that participants' performance in the high-lose in the iTBS group had stronger stimulation of theta spectral power than those in the sham group. Specifically, we found that under high-risk conditions, compared with the control group, the iTBS group showed significant activation of the theta spectrum power in the FPZ, FZ, FCZ, and CZ regions after treatment.Conclusions: Our results provide evidence that long-term iTBS stimulation effectively improves the decision-making ability of schizophrenia. After receiving negative feedback, patients can turn to safety options. These findings support that iTBS may be a potential treatment for clinical decision-making disorders.

Global and Parallel Cortical Processing Based on Auditory Gamma Oscillatory Responses in Humans.

Gamma oscillations are physiological phenomena that reflect perception and cognition, and involve parvalbumin-positive γ-aminobutyric acid-ergic interneuron function. The auditory steady-state response (ASSR) is the most robust index for gamma oscillations, and it is impaired in patients with neuropsychiatric disorders such as schizophrenia and autism. Although ASSR reduction is known to vary in terms of frequency and time, the neural mechanisms are poorly understood. We obtained high-density electrocorticography recordings from a wide area of the cortex in 8 patients with refractory epilepsy. In an ASSR paradigm, click sounds were presented at frequencies of 20, 30, 40, 60, 80, 120, and 160 Hz. We performed time-frequency analyses and analyzed intertrial coherence, event-related spectral perturbation, and high-gamma oscillations. We demonstrate that the ASSR is globally distributed among the temporal, parietal, and frontal cortices. The ASSR was composed of time-dependent neural subcircuits differing in frequency tuning. Importantly, the frequency tuning characteristics of the late-latency ASSR varied between the temporal/frontal and parietal cortex, suggestive of differentiation along parallel auditory pathways. This large-scale survey of the cortical ASSR could serve as a foundation for future studies of the ASSR in patients with neuropsychiatric disorders.