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Modified Nomenclature for the "10%" Electrode System1
Abstract
A modified nomenclature for designating the auxiliary electrodes of the 10% system is described.
Copyright (C) 1988 American Clinical Neurophysiology Society
... Recruiters' and candidates' EEG activity was recorded, according to the hyp ning specifics, via two lean 15-channels EEG systems. Electrodes were placed i spondence to F7, F3, Fz, F4, F8, T7, C3, Cz, C4, T8, P3, Pz, P4, O1, and O2 electro (SI10) [41], using Ag/AgCl sensors with physical reference in the two earlobes. vE monitored for subsequent signal processing. ...
... Recruiters' and candidates' EEG activity was recorded, according to the hyperscanning specifics, via two lean 15-channels EEG systems. Electrodes were placed in correspondence to F7, F3, Fz, F4, F8, T7, C3, Cz, C4, T8, P3, Pz, P4, O1, and O2 electrode sites (SI10) [41], using Ag/AgCl sensors with physical reference in the two earlobes. vEOG was monitored for subsequent signal processing. ...
We focused on job interviews as critical examples of complex social interaction in organizational contexts. We aimed at investigating the effect of face-to-face vs. computer-mediated interaction, of role (candidate, recruiter), and of the interview phase (introductory, attitudinal, technical, conclusive) on intra-brain and inter-brain connectivity measures and autonomic synchronization. Twenty expert recruiters and potential candidates took part in a hyperscanning investigation. Namely, electroencephalography (delta, theta, alpha, beta bands) and autonomic (skin-conductance, heart-rate) data were collected in candidate-recruiter dyads during a simulated job interview and then concurrently analyzed. Analyses highlighted a link between face-to-face condition and greater intra-/inter-brain connectivity indices in delta and theta bands. Furthermore, intra-brain and inter-brain connectivity measures were higher for delta and theta bands in the final interview phases compared to the first ones. Consistently, autonomic synchronization was higher during the final interview phases, specifically in the face-to-face condition. Finally, recruiters showed higher intra-brain connectivity in the delta range over frontal and temporoparietal areas, while candidates showed higher intra-brain connectivity in the theta range over frontal areas. Findings highlight the value of hyperscanning investigations in exploring social attunement in professional contexts and hint at their potential to foster neuroscience-informed practices in human resource management processes.
... During the participants' video watching, EEG recordings were collected using a 64-channel EEG Recorder (Neuracle Technology, Changzhou, China) at a sampling rate of 1000 Hz, and the electrode impedance was kept below 5 kΩ. Fifty-nine electrodes were selected from 64 electrodes that covered the entire scalp according to the international 10-10 system [28]: (Fpz, Fp1, Fp2, AF3, AF4, AF7, AF8, Fz, F1, F2, F3, F4, F5, F6, F7, F8, FCz, FC1, FC2, FC3, FC4, FC5, FC6, FT7, FT8, Cz, C1, C2, C3, C4, C5, C6, T7, T8, CP1, CP2, CP3, CP4, CP5, CP6, TP7, TP8, Pz, P3, P4, P5, P6, P7, P8, POz, PO3, PO4, PO5, PO6, PO7, PO8, Oz, O1, and O2). For further analyses, we divided the 59 electrodes into five regions: frontal (F), parietal (P), occipital (O), left temporal (LT), and right temporal (RT); this is shown in Fig. 2. All the collected EEG data were preprocessed in offline mode using the EEGLAB [29] toolbox, including baseline adjustment and removing power frequency interference and artifacts. ...
... We constructed the brain networks in three classical frequency bands for each participant: alpha (8-16 Hz), beta (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32), and gamma (32-63 Hz) [30]; these bands are related to cognitive and visual activities [30][31][32]. A bandpass filter was applied to the preprocessed EEG recordings to obtain the time series of the target bands. ...
To our knowledge, the present study is the first to use electroencephalography (EEG) to investigate the reorganizations of functional brain networks when watching 2D and 3D videos. We aimed to reveal the underlying neural mechanisms that may cause different visual experiences from a brain network perspective. The EEG activities of 40 healthy participants were recorded while watching 2D and 3D videos. By constructing multiband functional brain networks, we analyzed the network efficiencies from both macro- and micro-scales. We observed: 1) at the macro-scale, higher global efficiency in beta (16–32 Hz) and gamma (32–63 Hz) networks in the 3D group, and 2) at the micro-scale, higher occipital and parietal efficiencies in beta and gamma networks in the 3D group, and higher frontal efficiency in the alpha (8–16 Hz) network in the 2D group.
Furthermore, using a small subset of functional connectivity features as inputs, a support vector machine classifier was used to classify the brain states induced by watching 2D and 3D videos. We achieved a satisfactory classification accuracy of 0.908 with an area of 0.96 under the receiver operating characteristic curve, using the top 18 features extracted from the beta band. Our findings are expected to uncover the underlying neural mechanisms related to different visual experiences during 2D and 3D video viewing from a brain network perspective.
... In the present study, two different active stimulation conditions were implemented: anodal and cathodal stimulations of the lDLPFC. For both anodal and cathodal tDCS conditions, one electrode of 9 cm 2 (3 × 3 cm) was positioned over the lDLPFC (F3 position according to the extended 10-20 electrode reference system; Chatrian et al. 1988), while the 35 cm 2 (5 × 7 cm) reference electrode was applied over the left deltoid muscle. In both conditions, a constant current of 0.5 mA was applied for 19 min with an additional ramp-up/ramp-down period of 30 s at the start and end of the direct current stimulation. ...
... Depiction of the electrode positioning and the simulated current flow. a In the anodal as well as the cathodal condition, one electrode of 9 cm 2 (3 × 3 cm) was positioned over the left DLPFC (F3 position according to the extended 10-20 electrode reference system;Chatrian et al. 1988) while the 35 cm 2 (5 × 7 cm) reference electrode was applied over the left deltoid muscle. b Direct current flow during anodal stimulation using the HD-Explore software (version 3.0, Soterix Medical Inc., New York); the reverse flow during cathodal tDCS. ...
The head fake in basketball describes an action during which players gaze in one direction, but pass the ball to the opposite direction. This deception can be modeled in the lab as a kind of interference resolution task. In such tasks, the left dorsolateral prefrontal cortex (lDLPFC) has been shown to play a critical role. In the present study, transcranial direct current stimulation (tDCS) was used as a form of non-invasive brain stimulation to modify activity in the lDLPFC. In a pre-post design, anodal and cathodal tDCS were contrasted. A 9 cm 2 electrode was positioned over the lDLPFC, while a 35 cm 2 reference electrode was positioned over the left deltoid. In a sample of N = 50 healthy, young adults, we observed a trend towards a significant single-session tDCS effect on the head-fake effect. Specifically, it can be argued that anodal tDCS led to enhanced performance by reducing the interference effect produced by head fakes, when compared with cathodal tDCS. This result conforms to previous studies suggesting that neuromodulation of the lDLPFC impacts interference processing. Furthermore, these results bear important implications for the real-life application of tDCS as a tool for cognitive enhancement.
... To focalize the spatial excitability, a rather small stimulation electrode of 9 cm 2 (3 × 3 cm) was used. This electrode was positioned over the VMPFC (Fpz position according to the extended 10-20 electrode reference system; Chatrian et al. 1988). A reference electrode of 35 cm 2 (5 × 7 cm) was applied over the DLPFC (F3 position according to Chatrian et al. 1988). ...
... This electrode was positioned over the VMPFC (Fpz position according to the extended 10-20 electrode reference system; Chatrian et al. 1988). A reference electrode of 35 cm 2 (5 × 7 cm) was applied over the DLPFC (F3 position according to Chatrian et al. 1988). The contact between electrodes and scalp was made by electrode cream. ...
The processing of self-referential material is supposed to be located in the medial prefrontal cortex (MPFC) and in particular in the ventro-medial prefrontal cortex (VMPFC). A reliable method to assess effects of self-relevance is the so-called matching paradigm in which the prioritization of newly learned self-associations in comparison to non-self-relevant associations can be measured. To assess the connection of activation in the VMPFC and self-referential processing, we measured the self-prioritization effect (SPE) before and after experimentally manipulating activation in the VMPFC. We applied either excitatory or inhibitory stimulation to the VMPFC via transcranial direct current stimulation (tDCS). In a sample of N = 65 healthy adults, we found a significant SPE before and after both types of stimulation and, remarkably, no systematic change of the SPE due to the stimulation. These results are evidential against a direct dependence of the SPE from activation in the VMPFC, indicating either that the SPE differs from other, more elaborate self-effects, and thereby is processed in different brain areas, or that the connection of SPE and VMPFC is correlational rather than causal.
... The TI stimulation electrodes were placed at F3, P3, F4, and P4 (based on the International 10-10 Electroencephalography System [20], Fig. 3A). Specifically, F3 and P3 were designated as one alternating current, whereas F4 and P4 were allocated as another, with frequencies set at 2 kHz and 2.02 kHz (resulting in a frequency difference of 20 Hz). ...
Background
Temporal interference (TI) stimulation, an innovative non-invasive brain stimulation technique, has the potential to activate neurons in deep brain regions. The objective of this study was to evaluate the effects of repetitive TI stimulation targeting the lower limb motor control area (i.e., the M1 leg area) on lower limb motor function in healthy individuals, which could provide evidence for further translational application of non-invasive deep brain stimulation.
Methods
In this randomized, double-blinded, parallel-controlled trial, 46 healthy male adults were randomly divided into the TI or sham group. The TI group received 2 mA (peak-to-peak) TI stimulation targeting the M1 leg area with a 20 Hz frequency difference (2 kHz and 2.02 kHz). Stimulation parameters of the sham group were consistent with those of the TI group but the current input lasted only 1 min (30 s ramp-up and ramp-down). Both groups received stimulation twice daily for five consecutive days. The vertical jump test (countermovement jump [CMJ], squat jump [SJ], and continuous jump [CJ]) and Y-balance test were performed before and after the total intervention session. Two-way repeated measures ANOVA (group × time) was performed to evaluate the effects of TI stimulation on lower limb motor function.
Results
Forty participants completed all scheduled study visits. Two-way repeated measures ANOVA showed significant group × time interaction effects for CMJ height (F = 8.858, p = 0.005) and SJ height (F = 6.523, p = 0.015). The interaction effect of the average CJ height of the first 15 s was marginally significant (F = 3.550, p = 0.067). However, there was no significant interaction effect on the Y balance (p > 0.05). Further within-group comparisons showed a significant post-intervention increase in the height of the CMJ (p = 0.004), SJ (p = 0.010) and the average CJ height of the first 15 s (p = 0.004) in the TI group.
Conclusion
Repetitive TI stimulation targeting the lower limb motor control area effectively increased vertical jump height in healthy adult males but had no significant effect on dynamic postural stability.
... Direct current was applied by a four-channel constant current generator (DC-STIMULATOR by NeuroConn, Ilmenau, Germany). In all stimulation conditions, a 9 cm² (3 × 3 cm) electrode was positioned over the left IPC (corresponding to BA 39 and BA 40 at the CP5 position according to the 10-20 EEG electrode system; Chatrian et al., 1988), and a 35 cm² (5 × 7 cm) reference electrode was placed on the left deltoid muscle over the upper arm. ...
False memories during testimony are an enormous challenge for criminal trials. Exposure to post-event misinformation can lead to inadvertent creation of false memories, known as the misinformation effect. We investigated anodal transcranial direct current stimulation (tDCS) on the left inferior parietal lobe (IPL) during recall testing to enhance accurate recall while addressing the misinformation effect. Participants (N = 60) watched a television series depicting a fictional terrorist attack, then received an audio recording with misinformation, consistent information, and control information. During cued recall testing, participants received anodal or sham tDCS. Results revealed a robust misinformation effect in both groups, with participants falsely recalling on average 26.6% of the misinformed items. Bayesian statistics indicated substantial evidence in favour of the null hypothesis that there was no difference between groups in the misinformation effect. Regarding correct recall however, the anodal group exhibited significantly improved recall for items from the original video. Together, these results demonstrate that anodal tDCS of the left IPL enhances correct recall of the episodes from the original event without affecting false recall of misinformation. The findings support the IPL's role in recollection and source attribution of episodic memories.
... The electrode placements are typically based on the 10-20 system (Jasper, 1958), which was subsequently extended to a 10% electrode system (Chatrian et al., 1988) and beyond. The naming convention for electrode positions is as follows. ...
... During the experiment, subjects sat on a chair in an electrically and acoustically shielded room and were instructed to relax and to keep as still as possible during the test. The EEG montage included a cap with 32 scalp unipolar sensors placed according to the 10-20 system [31] and referred to linked mastoids, with the ground electrode at FPz. EEG was coupled with 4 electro-oculogram (EOG) sensors to detect vertical and horizontal eye-movements. Electrode impedance was kept lower than 5 KΩ. ...
Benzodiazepine (BDZ) misuse is a growing health problem, with 1–2% of patients under BDZ treatment meeting the criteria for use disorder or dependence. Although BDZ addiction potential has been known for decades, much remains unknown its effects on brain functions. The aim of this study was to assess the neuropsychological and neurophysiological profile of a group of chronic insomniacs taking long-term high doses of benzodiazepine. We recruited 17 consecutive patients admitted to our third-level Sleep Medicine Unit for drug discontinuation (7 males, mean age 49.2 ± 11.2 years, mean education 13.7 ± 3.9 years, mean daily diazepam-equivalent BDZ: 238.1±84.5 mg) and 17 gender/age-matched healthy controls (7 males, mean age 46.8 ± 14.1 years, mean education 13.5 ± 4.5 years). We performed a full neuropsychological evaluation of all subjects and recorded their scalp event-related potentials (Mismatch-Passive Oddball-Paradigm and Active Oddball P300 Paradigm). Patients with chronic insomnia and BDZ use disorder showed a profound frontal lobe executive dysfunction with significant impairment in the cognitive flexibility domain, in face of a preserved working, short and long-term memory. In patients, P300 amplitude tended to be smaller, mainly over the frontal regions, compared to controls. BDZ use disorder has a severe cognitive impact on chronic insomnia patients. Long-term high-dose BDZ intake should be carefully evaluated and managed by clinicians in this specific patient population, especially in relation to risky activities.
... It is generally accepted that increasing the number of electrodes yields more precise localization [22,23,25]. The number of electrodes 145 146 146 has evolved towards high-density numbers with the introduction of the standard 10-10 positioning system [81,258] introducing up to 70 locations, and with the introduction of the 10-5 system [83] the number was elevated to 345 locations for scalp coverage. While the 10-10 system was accepted as a standard by the ACNS and the IFCN [82,259], the 10-5 system was not accepted by either of them [260]. ...
In this thesis, multiple approaches for electroencephalographic (EEG) source reconstruction using low-density electrode counts are introduced. Source reconstruction provides valuable information about the location and time-courses of the source activity in the brain cortical areas. For such estimation, the use of a high number of electrodes has been proven to provide the most accurate estimation of the underlying brain activity. However, high-density EEG (hdEEG) is not generalized for most EEG applications, thus neither is the use of the source estimated activity. Although source reconstruction can provide spatially segregated time courses and relevant information about the dynamical interaction of brain regions, most EEG applications still rely on analysis and feature extraction from the electrode space.
This thesis provides a link between source reconstruction and low-density EEG (ldEEG) systems. It presents a set of rigorous methodologies designed to identify EEG electrodes according to their contribution to localization accuracy and minimizes their numbers through optimization routines. hdEEG is taken as the reference for source imaging when mapping a particular brain activity or the activity of a region of interest (ROI). Previous works have studied the influence of the spatial sampling (number of electrodes) in brain generalized source reconstruction, where the positions of the electrodes were selected to attempt covering the entire head/scalp. In contrast, this work presents approaches to identify and select electrode locations based on their relevance to capture the underlying activity or their contribution to obtain accurate reconstructions of the activity of interest, while using the lowest number of electrodes possible.
Simplifying the number of electrodes while obtaining detailed information of the source activity can be beneficial for multiple EEG applications. It can serve to improve portability, enabling recordings to be taken in more natural environments outside the lab; to design easy-to-use devices that can monitor the source activity for different neuroparadigms/applications; to reduce the accessibility boundaries to non-traditional EEG users; and to expand the research scope of EEG based source activity reconstruction. For these purposes, three methodologies are introduced in this work. The first study consists of constraining the estimation to a set of frequency modes extracted in the electrode space prior to source activity reconstruction. The method of Multivariate Empirical Mode Decomposition (MEMD) was applied to extract the frequency modes of the underlying source activity in ldEEG electrode configuration.
A second study consists of the use of spatial constraints, in which the estimation is conferred to a section of the brain, using a priori knowledge of the general location of the source activity. For this, a technique based on partial models of the brain is combined with relevance-based electrode selection using a Q-alpha method for relevance feature selection, in order to determine the most relevant electrode positions that can be used to map a region of interest. In addition, when considering the full brain model, relevance selection is compared in multiple electrode scenarios to compare the accuracy of the reduced number of electrodes with denser systems. A third study consists of electrode selection based on its contribution to localization accuracy, and a methodology combining evolutionary optimization and source reconstruction is introduced. The non-dominated sorting genetic algorithm II (NSGA-II) is applied to identify optimal combinations of electrodes that offer the best source reconstruction accuracy.
The results show the feasibility of identifying reduced electrode counts that offer an equal or better reconstruction quality. In most cases, electrode counts between 6 and 12 electrodes are found to maintain the hdEEG accuracy of electrode counts with 128 electrodes. This represents an important reduction in the number of electrodes while maintaining high accuracy; demonstrating that a set of a few electrodes can be used to estimate the source activity in a particular scenario. The frameworks established here can serve to evaluate to what extent current systems with reduced electrode counts can be used for source reconstruction, and to identify the optimal electrode positions for different neuro-paradigms and applications.
... The distance between two adjacent electrodes is 10 to 20% of the skull extremities' total distance. The 10-10 standard [34] was developed with more electrodes (74). Table 1 explains the electrode function for each brain area. ...
Recently, motor imagery EEG signals have been widely applied in Brain–Computer Interfaces (BCI). These signals are typically observed in the first motor cortex of the brain, resulting from the imagination of body limb movements. For non-invasive BCI systems, it is not apparent how to locate the electrodes, optimizing the accuracy for a given task. This study proposes a comparative analysis of channel signals exploiting the Deep Learning (DL) technique and a public dataset to locate the most discriminant channels. EEG channels are usually selected based on the function and nomenclature of electrode location from international standards. Instead, the most suitable configuration for a given paradigm must be determined by analyzing the proper selection of the channels. Therefore, an EEGNet network was implemented to classify signals from different channel location using the accuracy metric. Achieved results were then contrasted with results from the state-of-the-art. As a result, the proposed method improved BCI classification accuracy.
... Two infrared wavelengths (730 and 850 nm) emitted by the transmitter were received by a pair of adjacent detectors with an interval of 30 mm, and were collected at a sampling rate of 10 Hz. The source probe and detector could form 24 channels according to the placement of the 10-20 systems (Chatrian et al., 1988;Oostenveld and Praamstra, 2001;Fornia et al., 2020a). The position of the source probe and detector in this study were shown in Figure 2. ...
Background
Mirror visual feedback (MVF) has been widely used in neurological rehabilitation. Due to the potential gain effect of the MVF combination therapy, the related mechanisms still need be further analyzed.
Methods
Our self-controlled study recruited 20 healthy subjects (age 22.150 ± 2.661 years) were asked to perform four different visual feedback tasks with simultaneous functional near infrared spectroscopy (fNIRS) monitoring. The right hand of the subjects was set as the active hand (performing active movement), and the left hand was set as the observation hand (static or performing passive movement under soft robotic bilateral hand rehabilitation system). The four VF tasks were designed as RVF Task (real visual feedback task), MVF task (mirror visual feedback task), BRM task (bilateral robotic movement task), and MVF + BRM task (Mirror visual feedback combined with bilateral robotic movement task).
Results
The beta value of the right pre-motor cortex (PMC) of MVF task was significantly higher than the RVF task (RVF task: -0.015 ± 0.029, MVF task: 0.011 ± 0.033, P = 0.033). The beta value right primary sensorimotor cortex (SM1) in MVF + BRM task was significantly higher than MVF task (MVF task: 0.006 ± 0.040, MVF + BRM task: 0.037 ± 0.036, P = 0.016).
Conclusion
Our study used the synchronous fNIRS to compare the immediate hemodynamics cortical activation of four visual feedback tasks in healthy subjects. The results showed the synergistic gain effect on cortical activation from MVF combined with a soft robotic bilateral hand rehabilitation system for the first time, which could be used to guide the clinical application and the future studies.
... EEG was recorded with a DC amplifier (SynAmps system, Compumedics Neuroscan Inc., Charlotte, NC, USA), and then processed offline via Vision Analyzer2 software (Brain Products GmbH, Gilching, Germany). The recording montage was constituted by 15 sintered Ag/AgCl electrodes-Fp1, Fp2, F3, Fz, F4, T7, C3, Cz, C4, T8, P3, Pz, P4, O1, and O2-referenced to linked earlobes and placed according to the 10-10 International System [31]. Electrodes impedance was kept under 5 kΩ and vEOG was recorded in order to keep track of ocular artifacts for subsequent correction and rejection. ...
While outcomes of embodied awareness practices in terms of improved posture and flexibility, movement efficiency, and well-being are often reported, systematic investigations of such training effects and of the actual nature, extent, and neurofunctional correlates of learning mechanisms thought to lie at the core of such practices are very limited. The present study focused on the Feldenkrais method (FM), one of the most established embodied awareness practices, and aimed at investigating the neurofunctional outcomes of the somatic learning process at the core of the method by testing the modulations induced by a standardized FM protocol on the complexity of practicers’ body structural map and on the activity of their sensorimotor network during different movement-related tasks (i.e., gestures observation, execution, and imagery). Twenty-five participants were randomly divided into an experimental group—which completed a 28-session FM protocol based on guided group practice—and a control group, and underwent pre-/post-training psychometric and electrophysiological assessment. Data analysis highlighted, at the end of the FM protocol, a significant increase of EEG markers of cortical activation (task-related mu desynchronization) in precentral regions during action observation and in central regions during action execution and imagery. Also, posterior regions of the sensorimotor network showed systematic activation during all the action-related tasks.
... Among these standards, the 10-20 system is typical of those proposed by [42] ( Figure 1. The 10-10 system [43] and the 10-5 system [44] are extensions of the 10-20 system for acquiring high-resolution EEG signals. EEGs are typically described in terms of (1) regular activity and (2) transient activity. ...
The majority of studies in the field of developing identification and authentication protocols for Internet of Things (IoT) used cryptographic algorithms. Using brain signals is also a relatively new approach in this field. EEG signal-based authentication algorithms typically use feature extraction algorithms that require high processing time. On the other hand, the dynamic nature of the EEG signal makes its use for identification/authentication difficult without relying on feature extraction. This paper presents an EEG-and fingerprint-based two-stage identification-authentication protocol for remote healthcare, which is fast, robust, and multilayer-based. A modified Euclidean distance pattern matching method is proposed to match the EEG signal in the identification stage due to its dynamic nature. The authentication stage is also an optimized method with the Genetic Algorithm (GA), which utilizes a modified Diffie–Hellman algorithm. Due to the vulnerability of the Diffie–Hellman algorithm to different types of attacks, the parameters used for this algorithm are extracted from the fingerprint and the EEG signal of the patient to provide a fast and robust authentication method. The proposed method is evaluated using data from patients with spinal cord injuries. Simulating results demonstrated high identification and authentication accuracy of the proposed method. Furthermore, it is extremely fast and efficient. © 2021 The Authors. IET Communications published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology
... Direct current was applied by a four-channel constant current generator (DC-STIMULATOR by NeuroConn, Ilmenau, Germany). In all stimulation conditions a 9 cm² (3 × 3 cm) electrode was positioned over the left ATL (corresponding to BA 38 at the midpoint between F7, T7 and FT9 position according to the 10-20 EEG electrode system; Chatrian et al., 1988), while a 35 cm² (5 × 7 cm) reference electrode was placed on the left deltoid muscle. The localization procedure for the stimulation condition is similar to a previous TMS study targeting the ATL ; targeted the midpoint between T7 and FT7. ...
Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation that has been used to modulate human brain activity and cognition. One area which has not yet been extensively explored using tDCS is the generation of false memories. In this study, we combined the DRM task with stimulation of the left anterior temporal lobe (ATL) during retrieval. This area has been shown to be involved in semantic processing in general and retrieval of false memories in the DRM paradigm in particular. During stimulation, 0.7 mA were applied via a 9cm² electrode over the left ATL, with the 35cm² return electrode placed over the left deltoid. We contrasted the effects of cathodal, anodal, and sham stimulation, which were applied in the recognition phase of the experiment on a sample of 78 volunteers. Results showed impaired recognition of true memories after both anodal and cathodal stimulation in comparison to sham stimulation, suggesting a reduced signal-to-noise ratio. In addition, the results revealed enhanced false recognition of concept lure items during cathodal stimulation compared to anodal stimulation, indicating a polarity-dependent impact of tDCS on false memories in the DRM task. The pathway by which tDCS modulated false recognition remains unclear: stimulation may have changed the activation of irrelevant lures or affected the weighting and monitoring of lure activations. Nevertheless, these results are a first step towards using brain stimulation to decrease false memories. Practical implications of the findings for real-life settings, e.g., in the courtroom, need to be addressed in future work.
... Direct current was provided by a constant current stimulator (4-channel-DC-stimulator by NeuroConn, Ilmenau). In the anodal as well as the sham condition (i.e., the control condition with faked stimulation), one electrode of 9 cm² (3 x 3 cm) was positioned over the right DLPFC (F4 position according to the extended 10-20 electrode reference system; (Chatrian, Lettich, & Nelson, 1988)), while the 35 cm² (5 x 7 cm) reference electrode was applied over the left deltoid muscle (Figure 2A). The F4 position translates to a maximal stimulation of the right MFG (Okamoto et al., 2004). ...
As digital gaming has grown from a leisure activity into a competitive endeavor with college scholarships, celebrity, and large prize pools at stake, players search for ways to enhance their performance, including through coaching, training, and employing tools that yield a performance advantage. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that is presently being explored by esports athletes and competitive gamers. Although shown to modulate cognitive processing in standard laboratory tasks, there is little scientific evidence that tDCS improves performance in digital games, which are visually complex and attentionally demanding environments. We applied tDCS between two sessions of the Stop-Signal Game (SSG; Friehs, Dechant, Vedress, Frings, & Mandryk, 2020). The SSG is a custom-built infinite runner that is based on the Stop-Signal Task (SST; Verbruggen et al., 2019). Consequently, the SSG can be used to evaluate response inhibition as measured by Stop-Signal Reaction Time (SSRT), but in an enjoyable 3D game experience. We used anodal, offline tDCS to stimulate the right dorsolateral prefrontal cortex (rDLPFC); a 9 cm² anode was always positioned over the rDLPFC while the 35 cm² cathode was placed over the left deltoid. We hypothesized that anodal tDCS would enhance neural processing (as measured by a decrease in SSRT) and improve performance, while sham stimulation (i.e., the control condition with a faked stimulation) should lead to no significant change. In a sample of N = 45 healthy adults a significant session x tDCS-condition interaction emerged in the expected direction. Subsequent analysis confirmed that the statistically significant decrease in SSRT after anodal tDCS to the rDLPFC was not due to a general change in reaction times. These results provide initial evidence that tDCS can influence performance in digital games.
... EEG data were acquired using a SynAmps system (Compumedics Neuroscan, Inc., Charlotte, NC, USA). The recording montage included 26 electrode sites -F7, F3, Fz, F4, F8, FC5, FC1, FCz, FC2, FC6, C3, Cz, C4, CP5, CP1, CP2, CP6, T7, T8, P7, P3, Pz, P4, P8, O1, and O2 [10/10 International System (Chatrian et al., 1988)] -and linked earlobe references. Scalp electrical potential was recorded via Ag/AgCl electrodes and sampled at 100 Hz with a 0.01-250 Hz input bandpass filter and a 50 Hz notch filter. ...
According to implicit accounts, human self-awareness grounds on the so-called sense of ownership (SoO). Empirical investigations of SoO have mostly focused on the manipulation of self-ascription of sensations and experiences involving the body via the induction of bodily illusions, such as the Rubber-Hand Illusion (RHI). While it has been proposed that the affective dimension necessarily contributes to the development of a full ownership ascription, the relationship between affective experience and body ownership still presents many open questions. This study thus aimed at investigating the boundaries of ownership ascriptions and the extent to which an external object can be incorporated within one’s own body representation, with a specific focus on the possibility for it to become a potential object of own affective experience marked by specific electrophysiological responses. Therefore, we induced RHI in 16 participants and then applied an aversive vs. pleasant stimulation to the embodied external object, while monitoring their electrophysiological activity for central physiological markers of affective processing. Data analysis revealed the effect of the stimulation condition on alpha band power over frontal areas, with higher alpha power during the pleasant stimulation condition with respect to the aversive stimulation one over medial and right frontal electrode sites. The present findings add to the limited pieces of evidence concerning the link between experiences of illusory body ownership, embodiment mechanisms, and affective factors, suggesting that the boundaries of body ownership might be extended to making incorporated objects the source of complex emotional responses beyond basic defensive reactions.
... EEG was recorded using 64 Ag-AgCl pin-type active electrodes (Brain Products, Munich, Germany), which were mounted according to the 10-10 system [50], and referenced to FCz. ...
OBJECTIVE: The neurophysiological processes involved in the generation of medically-unexplained symptoms (MUS) remain unclear. This study tested three assumptions of the perception-filter model contributing to MUS: (I.) increased bodily signal strength (II.) decreased filter function, (III.) increased perception.
METHODS: In this cross-sectional, observational study, trait MUS was assessed by a web-based survey (N = 486). The upper and lower decile were identified as extreme groups of high (HSR; n = 29; 26 women; Mage = 26.0 years) and low symptom reporters (LSR; n = 29; 21 women; Mage = 28.4 years). Mean heart rate (HR) and heart rate variability (HRV), and cortisol awakening response (CAR) were assessed as indicators of bodily signal strength (I.). Heartbeat-evoked potentials (HEPs) were assessed during rest and a heartbeat perception task. HEPs reflect attentional resources allocated towards heartbeats and served as index of filter function (II.). Interoceptive accuracy (IAc) in heartbeat perception was assessed as an indicator of perception (III.).
RESULTS: HSR showed higher HR and lower HRV (RMSSD) than LSR (I.), but no differences in CAR. HSR exhibited a stronger increase of HEPs when attention was focused on heartbeats than LSR (II.); there were no group differences in IAc (III.).
CONCLUSIONS: The perception-filter model was partially confirmed in that HSR showed altered bodily signals suggesting higher sympathetic activity (I.); higher HEP increases indicated increased filter function for bodily signals (II.). As more attentional resources are mobilized to process heartbeats, but perception accuracy remains unchanged (III.), this overflow could be responsible for detecting minor bodily changes associated with MUS.
... EEG data were recorded from 60 active Ag/AgCl scalp electrodes of the 10% system (Chatrian, Lettich, & Nelson, 1988), using a digital BrainAmp amplifier (Brain Products, Gilching, Germany). The electrooculogram (EOG) was monitored from electrodes below and above the right eye and from the outer left and right canthi. ...
Using event-related potentials we examined the mechanisms that underlie the influence of affective context information on evaluative judgments in affective priming (AP). Participants (N = 44) evaluated a priori neutral target ideographs that were preceded by 800-ms negative, neutral or positive prime pictures. We observed a significant AP effect (APE), with more positive target ratings for targets following positive versus negative primes, with neutral primes lying in between. A greater individual APE was associated with increased attention for the primes, indicated by larger amplitudes of parietal positive slow wave (PSW) and more pronounced prime affect discrimination mirrored in affect-specific variations of parieto-occipital prime P1 and parietal prime P2, P300, and PSW amplitudes. This confirms previous theoretical and empirical work suggesting that the size of the APE critically depends on the extent of prime-elicited affective activation. Furthermore, a greater individual APE was related to generally reduced depth of target processing as mirrored in smaller overall amplitudes of attention-sensitive target-related P1, P2, P300, and PSW. In addition, in the total sample P2, P300, and PSW were smaller for targets following AP eliciting, attention-capturing emotional, as compared to neutral primes. Based on the observed coincidence of increased processing of affective versus neutral primes, and specifically reduced processing of those targets that followed affective primes, we propose prime-target resource competition as an additional, not yet described process contributing to AP in the neutral-target paradigm.
... In the present study, two different stimulation conditions were implemented: an active stimulation condition utilizing anodal offline tDCS and a sham stimulation condition. In the anodal as well as the sham condition one electrode of 9 cm² (3 x 3 cm) was positioned over the left DLPFC (F3 Position according to the extended 10-20 electrode reference system (Chatrian, Lettich, & Nelson, 1988), while the 35 cm² (5 x 7 cm) reference electrode was applied over the left deltoid muscle ( Figure 1C). In the anodal stimulation condition a constant current of 0.5 mA was applied for 19 min, with additional 30-second ramp up and ramp down periods at the start and end of the simulation. ...
The effect of stress on working memory has been traced back to a modulation of the prefrontal cortex (PFC). We investigated the effects of neuromodulation of the left dorsolateral prefrontal cortex (lDLPFC) after exposure to psychosocial stress through the Socially Evaluated Cold Pressure Test (SECPT). The hypothesis was that neuromodulation interacts with the stress intervention, to either boost performance even under stressed conditions or compensate negative stress effects. Fifty-nine participants were randomly divided into two groups. One group received active, anodal, offline transcranial direct current stimulation (tDCS) over the lDLPFC while the other group received sham stimulation. Participants performed a lexical n-back task, before and after the SECPT and tDCS intervention. The first n-back task was used as a baseline measurement and the second n-back task was performed during recovery from stress when cortisol levels are at their peak, but still under the influence of tDCS aftereffects. Additionally, after the psychosocial stress phase participants were post-hoc divided into cortisol responders and nonresponders. Results showed that generally stress increased lexical n-back task performance as indicated by faster correct reaction times and higher accuracy but that this was not modulated by tDCS. Crucially, using Bayes analysis we obtained evidence against the influence of anodal tDCS on stressed individual’s working memory performance.
... EEG was recorded during awake, resting state in all participants as they were seated on a comfortable couch with eyes-closed in a dimly lit, sound-attenuated RF-shielded booth (Industrial Acoustics, Inc., Bronx, NY, USA). A 61-channel electrode cap (Electro-Cap International, Inc., Eaton, OH, USA) based on the Extended 10-20 System [74][75][76][77] was used. The reference electrode was at the tip of the nose, and the ground electrode was placed at the forehead. ...
: Individuals with alcohol use disorder (AUD) manifest a variety of impairments that can be attributed to alterations in specific brain networks. The current study aims to identify features of EEG-based functional connectivity, neuropsychological performance, and impulsivity that can classify individuals with AUD (N = 30) from unaffected controls (CTL, N = 30) using random forest classification. The features included were: (i) EEG source functional connectivity (FC) of the default mode network (DMN) derived using eLORETA algorithm, (ii) neuropsychological scores from the Tower of London test (TOLT) and the visual span test (VST), and (iii) impulsivity factors from the Barratt impulsiveness scale (BIS). The random forest model achieved a classification accuracy of 80% and identified 29 FC connections (among 66 connections per frequency band), 3 neuropsychological variables from VST (total number of correctly performed trials in forward and backward sequences and average time for correct trials in forward sequence) and all four impulsivity scores (motor, non-planning, attentional, and total) as significantly contributing to classifying individuals as either AUD or CTL. Although there was a significant age difference between the groups, most of the top variables that contributed to the classification were not significantly correlated with age. The AUD group showed a predominant pattern of hyperconnectivity among 25 of 29 significant connections, indicating aberrant network functioning during resting state suggestive of neural hyperexcitability and impulsivity. Further, parahippocampal hyperconnectivity with other DMN regions was identified as a major hub region dysregulated in AUD (13 connections overall), possibly due to neural damage from chronic drinking, which may give rise to cognitive impairments, including memory deficits and blackouts. Furthermore, hypoconnectivity observed in four connections (prefrontal nodes connecting posterior right-hemispheric regions) may indicate a weaker or fractured prefrontal connectivity with other regions, which may be related to impaired higher cognitive functions. The AUD group also showed poorer memory performance on the VST task and increased impulsivity in all factors compared to controls. Features from all three domains had significant associations with one another. These results indicate that dysregulated neural connectivity across the DMN regions, especially relating to hyperconnected parahippocampal hub as well as hypoconnected prefrontal hub, may potentially represent neurophysiological biomarkers of AUD, while poor visual memory performance and heightened impulsivity may serve as cognitive-behavioral indices of AUD.
... The design, specification, maintenance and calibration protocols for electrodes [99][100][101][102][103][104][105][106][107][108][109], electrode placement systems [109][110][111][112][113][114][115][116][117][118], use of ground and reference electrodes, EEG machines (analog, digital or multi-channel), EEG calibrators and montages [119] are governed by stringent standards and guidelines [120][121][122][123][124][125][126][127][128][129]. EEG recording procedures are categorized into two stages: a) data acquisition and pre-processing, and b) feature extraction. ...
... For the stimulation of Wernicke's area (W1) and of the right-hemisphere homologous area (W2), the coil was centered over CP5 and CP6 of the International 10-20 System, respectively. According to the literature, this site correlates best with the location of Wernicke's area (24)(25)(26). The primary visual cortex was stimulated at the occiput (27). ...
Introduction: Single-pulse transcranial magnetic stimulation (TMS) and high-frequency repetitive TMS (rTMS) over Wernicke's area were found to facilitate language functions in right-handed healthy subjects. We aimed at investigating the effects of excitatory rTMS, given as intermittent theta burst stimulation (iTBS) over left Wernicke's area, on auditory comprehension in patients suffering from fluent aphasia after stroke of the left temporal lobe.
Methods: We studied 13 patients with chronic fluent aphasia after an ischemic stroke involving Wernicke's area. iTBS was applied in random order to Wernicke's area, the right-hemisphere homologous of Wernicke's area, and the primary visual cortex. Auditory comprehension was blind assessed using the Token test before (T0), 5 (T1), and 40 min (T2) after a single session of iTBS.
Results: At the first evaluation (T1) after iTBS on left Wernike's area, but not on the contralateral homologous area nor on the primary visual cortex, the scores on the Token test were significantly increased. No significant effects were observed at T2.
Conclusion: We demonstrated that a single session of excitatory iTBS over Wernicke's area was safe and led to a transient facilitation of auditory comprehension in chronic stroke patients with lesions in the same area. Further studies are needed to establish whether TBS-induced modulation can be enhanced and transformed into longer-lasting effects by means of repeated TBS sessions and by combining TBS with speech and language therapy.
... EEG was recorded continuously from 60 active Ag/AgCl scalp electrodes of the international 10% system (Chatrian, Lettich, & Nelson, 1988) using a digital ActiCap/BrainAmp system (Brain Products, Gilching, Germany). Recording was online referenced to FCz and rereferenced offline against algebraically linked mastoids (TP9, TP10). ...
We used event-related potentials (ERPs) to investigate the mental processes that contribute to affective priming (AP), a systematic shift of evaluative judgments about neutral targets toward the valence of preceding primes. 64 participants rated their liking of a priori neutral ideographs preceded by 800-ms emotional primewords, while 64-channel EEG was recorded. We observed a significant AP effect that was closely associated with prime valence dependent variations of the right central-to-parieto-occipital positive slow wave (PSW) amplitude in the target ERP, providing evidence for implicit affect misattribution as one source of the effect. While deeper target processing mirrored in valence unspecific central-to-parieto-occipital target PSW amplitude was negatively associated with AP, deeper prime processing indicated by valence unspecific central-to-parieto-occipital prime PSW amplitude was positively related to AP. These depth of processing effects underline the importance of strategic processes in AP. In a stepwise linear regression analysis, the prime valence effect on right central-to-parieto-occipital target PSW indicating affect misattribution and the two valence-unspecific ERP indices of processing depth (central-to-parieto-occipital prime- and target PSW) were independent predictors of the size of the AP effect. Together they accounted for 60% of the variance. Furthermore, an explorative analysis provided first evidence for the relevance of early discrimination of prime valence for AP.
... 1. Wernicke's area. NOTE: The stimulation electrode placement that best corresponds to Wernicke's area is CP5 according to the extended International 10-20 system for EEG 16,17 . 1. To locate this location in the absence of an electrode cap, follow the standard 10-20 system procedures. ...
Language is a highly important yet poorly understood function of the human brain. While studies of brain activation patterns during language comprehension are abundant, what is often critically missing is causal evidence of brain areas' involvement in a particular linguistic function,
not least due to the unique human nature of this ability and a shortage of neurophysiological tools to study causal relationships in the human brain noninvasively. Recent years have seen a rapid rise in the use of transcranial direct current stimulation (tDCS) of the human brain, an
easy, inexpensive and safe noninvasive technique that can modulate the state of the stimulated brain area (putatively by shifting excitation/ inhibition thresholds), enabling a study of its particular contribution to specific functions. While mostly focusing on motor control, the use of tDCS is becoming more widespread in both basic and clinical research on higher cognitive functions, language included, but the procedures for its application remain variable. Here, we describe the use of tDCS in a psycholinguistic word-learning experiment. We present the techniques
and procedures for application of cathodal and anodal stimulation of core language areas of Broca and Wernicke in the left hemisphere of the human brain, describe the procedures of creating balanced sets of psycholinguistic stimuli, a controlled yet naturalistic learning regime, and a comprehensive set of techniques to assess the learning outcomes and tDCS effects. As an example of tDCS application, we show that cathodal stimulation of Wernicke's area prior to a learning session can impact word learning efficiency. This impact is both present immediately after learning and, importantly, preserved over longer time after the physical effects of stimulation wear off, suggesting that tDCS can have long-term influence on linguistic storage and representations in the human brain.
... EEG was recorded continuously from 60 active Ag/AgCl scalp electrodes of the international 10% system ( Chatrian et al. 1988) using a digital ActiCap/BrainAmp system (Brain Products, Gilching, Germany). Data were sampled at 500 Hz and recorded with a bandpass filter from 0.1 to 70 Hz. ...
In the present study event-related potentials were used to shed further light on the neural signatures of active inhibition of the (affective) content of written words. Intentional inhibition was implemented by simply asking participants (N = 32) to ignore single words that served as primes in an affective priming (AP) task. In AP, evaluations about a priori neutral targets typically tend to shift towards the valence of preceding primes, denoting an AP effect (APE). To create a plausible cover-context emphasizing the usefulness of word inhibition, participants were asked to avoid this shift, that is, to make unbiased target evaluations. Ignoring the prime words was suggested as the most efficient strategy to achieve this aim. Effective inhibition of the words’ (affective) content, as suggested by a significant APE present for words processed without any further instruction, but not for ignored ones, affected multiple stages of processing. On the neuronal level, word inhibition was characterized by reduced early perceptual (left-lateralized word-specific N170), later attentional (parietal P300), and affective-semantic processing (reduced posterior semantic asymmetry). Furthermore, an additional recruitment of top-down inhibitory control processes, which was mirrored in increased amplitudes of medial-frontal negativity, showed to be critically involved in intentional word inhibition.
... The EEG signal was continuously sampled and digitalized at 500 Hz. EEGs were recorded from 30 electrode sites using a subset of the 10-10 system (Chatrian, lettich, & Nelson, 1988) provided by Easy Cap. Vertical and horizontal EOGs were recorded from 2 bipolar electrodes placed on the infra-orbital ridges of the left and the right eye and the outer canthi of the two eyes. ...
... EEG data were recorded with a BrainAmp DC amplifier (Brain Products GmbH, Munich, Germany), with an online low cutoff filter of 0 Hz and an online high cutoff filter of 1,000 Hz via BrainVision Recorder software, version 1.20 (Brain Products). Active silver/silver-chloride electrodes were attached in accordance with the International 10-10 system (Chatrian, Lettich, & Nelson, 1988) at 29 electrode sites (F7, F3, Fz, F4, F8, FC5, FC1, FC2, FC6, T7, C3, Cz, C4, T8, CP5, CP1, CP2, CP6, P7, P3, Pz, P4, P8, PO9, O1, Oz, O2, PO10; FCz served as online reference) on a 32channel ActiCAP electrode cap (ActiCAP; Brain Products). Horizontal eye movements were recorded with an electrode placed lateral to the left outer canthus. ...
Feedback-based learning initiated by dopamine (DA) cell firing is crucial for adaptive behavior. The nature and context of feedback can vary, however, affecting how feedback is processed. For example, the feedback-related negativity (FRN) in the ERP in humans, which has been linked to the DA system, is reduced for delayed feedback and for observational compared to active learning. Recent research suggested that oscillations in the theta and beta band over the medio-frontal cortex reflect distinct feedback processing mechanisms. In this study, we hypothesized that the power in both frequency bands is affected by feedback delay and agency. We thus investigated effects of feedback delay (1 s vs. 7 s) on induced theta and beta band power and the FRN in a probabilistic feedback learning task in two participant groups, one learning actively and one by observation. For theta and beta, a larger power difference between negative and positive feedback for immediate than delayed feedback was found, driven by positive feedback for beta and by negative feedback for theta, while no differential modulation by agency was seen for theta or beta power following positive and negative feedback. These results indicate that feedback-locked beta and theta both reflect neural processes that are specific for the integration of feedback and recently preceding events, possibly linked to cognitive control and memory. With respect to the FRN amplitude, we could replicate previous findings of both delay and agency modulations, suggesting that the neural processes underlying feedback-locked ERPs and theta and beta power modulations differ.
... In addition to SPS, which is the most basic stimulation, we also examined continuous theta-burst stimulation (TBS) [2,51], which seems to be the most useful rTMS in studying cognitive functions because of the prevalence and reasonable duration of effects. Moreover, the high-resolution extended 10-20 system (10-10 system) [52,53] was applied to the lateral prefrontal cortex, which can be used to estimate the discomfort and intolerability of stimulation of any region in the lateral prefrontal cortex. ...
Transcranial magnetic stimulation (TMS) of the human lateral prefrontal cortex, particularly the ventral region, often causes considerable discomfort to subjects. To date, in contrast to abundant literature on stimulations to the dorsolateral prefrontal cortex, the ventrolateral prefrontal cortex has been less frequently stimulated, partly because some subjects are intolerable of stimulation to the ventrolateral prefrontal cortex. To predict the additional number of subjects required for the stimulation of the dorsolateral and ventrolateral prefrontal cortices, 20 young healthy subjects reported two evaluation scores: the discomfort caused by TMS and the resulting intolerability to complete the TMS experiments. Single-pulse stimulation (SPS) or theta-burst stimulation (TBS) was administered to the lateral prefrontal cortex. The high-resolution extended 10–20 system was used to provide accurate estimation of the voxelwise scores. The discomfort ratings with the SPS and TBS were relatively higher in the ventrolateral prefrontal cortex than those in the dorsolateral prefrontal cortex. Both the SPS and TBS elicited maximal discomfort at the stimulation position F8. The SPS and TBS to F8 under the standard TMS protocols were intolerable for approximately one half (11 and 10, respectively) of the subjects. The intolerability was further calculated for all voxels in the lateral prefrontal cortex, which enabled us to estimate the additional number of subjects required for specific target areas. These results suggest that prior knowledge of subjects’ discomfort during stimulation of the lateral prefrontal cortex can be of practical use in the experimental planning of the appropriate number of recruited subjects and provide the database for the probability of intolerability that can be used to predict the additional number of subjects.
... We analyzed 22 manually-identified trials and using the procedure presented in Graimann et al. 21 , which indicated 8-12 Hz frequency band at C2 location (of the 10-10 standardized EEG electrode positioning system 22 ...
Functional electrical stimulation therapy (FEST) is a state-of-the-art treatment for retraining motor function following neurological injuries. Recent literature suggests that FEST can be further improved with brain-computer interface (BCI) technology. In this case study, we assessed the feasibility of using BCI-triggered FEST (BCI-FEST) to restore upper-limb function in a 57-year old male with severe left hemiplegia resulting from a stroke six years prior to enrollment in the study. The intervention consisted of two blocks of 40 one-hour BCI-FEST sessions (total of 80 sessions) for the left upper limb, with three sessions delivered weekly. During therapy, a single-channel BCI was used to trigger the stimulation programmed to facilitate functional movements. The measure of the feasibility of the BCI-FEST included assessing the implementation and safety of the intervention. Clinical improvements were assessed using (i) Functional Independence Measure, (ii) Action Research Arm Test (ARAT), (iii) Toronto Rehabilitation Institute - Hand Function Test (TRI-HFT), and (iv) Fugl-Meyer Assessment Upper Extremity test (FMA-UE). Upon completion of 80 therapy sessions, 14-point, 17-point and 18-point changes were recorded on ARAT, FMA-UE and TRI-HFT, respectively. The participant also indicated improvement as demonstrated by his ability to perform various day-to-day tasks. The results suggest that BCI-FEST is safe and viable.
... Data were collected by using a 15-channel montage (Ag/AgCl electrodes referenced to linked earlobes, Figure 1). Sensors were placed according to the 10-10 International System (Chatrian et al., 1988). vEOG was also recorded in order to keep track of ocular artifacts for subsequent correction and rejection, so to avoid data contamination. ...
Purpose
The purpose of this paper is to test the potential of an innovative technology-mediated mental training protocol for the empowerment of stress management and neurocognitive efficiency in highly stressful professional contexts, with people who occupy top management positions. The innovative protocol specifically combines mindfulness practice and a wearable neurofeedback system managed via smartphone.
Design/methodology/approach
The longitudinal research included pre- and post-training assessment steps in order to test training effects with respect to subjective level and physiological markers of stress, anxiety and mood profiles, cognitive abilities and markers of neurocognitive efficiency.
Findings
Results showed decreased stress, anxiety, anger and mental fatigue; increased participants’ information-processing efficiency; increased electrophysiological markers concerning the balance and reactivity of the mind-brain system; and improved physiological markers of vagal tone.
Research limitations/implications
Though further investigation and replication with larger samples would strengthen present findings, the authors suggest that observed outcomes, together with the limited duration of the overall protocol and of daily practices, make the training a potentially valuable tool especially for people whose professional position imposes time limitations and elevated job duties, thus increasing the risk of drop-out from traditional stress management programs.
Originality/value
The combination of mindfulness-based mental training with the advantages offered by a novel brain-sensing wearable technology allows for overcoming the weak points of traditional approaches (e.g. notable time expense) and optimizing training opportunities and outcomes. Furthermore, this is, to the authors’ best knowledge, the first systematic report of the application of such methodology in an organization and with top management professionals.
... Event-related potential recording and analysis EEG was measured with an Acti-Cap system (Brain Products GmbH, Munich, Germany) from 32 electrodes (FP1, FP2, F7, F3, Fz, F4, F8, FC5, FC1, FCz, Fc2, FC6, T7, C3, Cz, C4, T8, Cp5, CP1, CP2, CP6, P7, P3, Pz, P4, P8, PO9, PO10, O1, Oz, and O2) according to the 10-10 electrode reference system [23] including the mastoids (TP9, TP10). Measurement reference was FCz, and AFz served as ground. ...
Negative priming (NP) refers to the finding that responses to previously irrelevant stimuli are impeded relative to responses to new stimuli. To date, NP has been demonstrated in the visual, auditory, and tactile sensory modalities with both inhibitory processes and retrieval-based processes contributing to the effect. To gain deeper insights into the role of both processes, event-related potentials (ERPs) have been measured during NP tasks with visual and separately with auditory stimuli. The specific patterns of ERP correlates are mixed, yet it can generally be concluded from previous research that amplitudes of both the N2 and the P3 reflect important components of NP. We present the first study to assess the ERP correlates of NP in the tactile modality. We observe a significant modulation of the P3 but not of the N2, thus providing tentative support for the existence of modality-specific differences in the ERP correlates of NP.
... The electroencephalogram was recorded with a QuickAmp (Brain Products, Gilching, Germany) DC-amplifier set at 200 Hz low-pass filtering from 64 scalp positions according to the 10/10 System (Chatrian, Lettich, & Nelson, 1985, 1988Jurcak, Tsuzuki, & Dan, 2007) using an EEG recording cap and Ag/AgCl ring electrodes (EASYCAP, Herrsching, Germany). ...
By means of event-related potentials (ERPs), the present study intended to extend previous findings on how the different processing stages of attentional selection are altered by the participants' motivational state depending on their saturation level. Forty-four normal-weight (mean BMI: 21.34, SD = 1.54), healthy participants aged between 19 and 34 years were assigned to a condition of hunger or satiety. While participants performed a central oddball task, task-irrelevant pictures (food vs. neutral) were presented unilaterally (either left or right from fixation) or bilaterally. Additionally, participants' eating and nutrition behaviour as well as their current level of hunger were assessed by self-reports. The results showed that while on the behavioural level groups did not show any differences in RTs and accuracy, ERPs of hungry participants show an enhanced early parieto-occipital activity 100–200 ms after stimulus onset (N1pc) for food pictures, particularly for high-calorie food. Furthermore, amplitudes of the N1pc co-varied significantly with the participants’ subjective feeling of hunger. 200–300 ms after stimulus onset, P2pc in hungry participants reveal a lack of differential processing of the food and neutral stimuli. Between 300 and 400 ms, food pictures were associated with an enlarged centro-parietal positivity (P3) in hungry compared to satiated participants, again especially for high-calorie food stimuli. From the perspective of motivated attention, the results of the present study suggest, that hunger may induce a state of heightened attention for food stimuli, although they were completely irrelevant for the current task. By that, salient food stimuli had an influence on early automatic attentional selection as well as on later and rather intention-driven processes of attentional “de-selection” and stimulus maintenance in normal-weight participants.
Learning often involves trial-and-error, i.e. repeating behaviours that lead to desired outcomes, and adjusting behaviour when outcomes do not meet our expectations and thus lead to prediction errors (PEs). PEs have been shown to be reflected in the reward positivity (RewP), an event-related potential (ERP) component between 200 and 350 ms after performance feedback which is linked to striatal processing and assessed via electroencephalography (EEG). Here we show that this is also true for delayed feedback processing, for which a critical role of the hippocampus has been suggested. We found a general reduction of the RewP for delayed feedback, but the PE was similarly reflected in the RewP and the later P300 for immediate and delayed positive feedback, while no effect was found for negative feedback. Our results suggest that, despite processing differences between immediate and delayed feedback, positive PEs drive feedback processing and learning irrespective of delay.
The perception-filter model posits that the generation of medically-unexplained symptoms is associated with (I.) more intense afferent bodily signals, (II.) impaired filter system activity to differentiate relevant from irrelevant signals, and (III.) altered perception of bodily signals. We tested these assumptions for cardiac perception in patients with somatoform disorders (SFD), patients with major depressive disorder (MDD) and healthy control (HC) individuals. Heart rate (variability; HR/HRV) and blood pressure served as indicators of bodily signals (I.); heartbeat-evoked potentials (HEPs) assessed during a heartbeat counting task (HCT) and a distraction task indicated filter system activity (II.); interoceptive accuracy (IAc) in the HCT was interpreted as an index of perception (III.). All indicators were assessed before and after a socially-evaluated cold pressor stress task (SECPT) and a control intervention. SFD patients (n = 24) showed higher average HR and diastolic blood pressure, as well as lower HRV than HC individuals (n = 22), but there were no differences in HEPs or IAc. Neither were there significant differences between the SFD and the MDD groups (n = 24), nor any stress effect on HEPs or IAc. Our findings suggest that increased intensity of bodily signals (I.) is the only model assumption that could be supported for patients with fully-developed SFD.
Collection of selected papers submitted and presented at the III Latin American Workshop on Computational Neuroscience (LAWCN'21), held in the city of São Luís do Maranhão, Brazil, from 8 to 10th December 2021. Papers have been peer-reviewed and selected for their superior quality and impact. Topics covered are within the areas of Computational Neuroscience, Artificial Intelligence, and Neuroengineering.
The neuron motor system has the ability to update the control strategy according to the environment. Intercepting a moving object is a task that can provide and study this ability. The aim of this study is to determine the performance and the control strategy on visual occlusion perturbation to intercepting moving targets. Sixteen subjects (24.4 ± 5.32 years old; 12 males and 4 females) were recruited. The experiment was carried out with a familiarization and an experimental phase where the participants managed a Physical Effector Machine (PEM) synchronized with a Virtual Interception Task (VIT). During the familiarization phase, participants learned the movement time (200 to 250 ms). In the experimental phase participants performed under two different conditions: Perturbation condition (PC), which corresponds to the target occlusion for 75 ms and 300 ms before expected movement onset and Control condition (CC) where there was no occlusion. In both conditions, the target moved at a constant velocity (145 cm.s−1). The results were analysed from the kinematics Movement time (MT), Relative time to peak velocity (%tPV), Correction Numbers (CN) and Spatial absolute-error (AE). The statistics were run by non-parametric Mann Whitney test to verify differences between CC and PC. The results showed a higher AE for PC than CC condition [U(159) = 16.738; p = .01; r = .43]. For the TM, %tPV and NC there were no differences between conditions. Our findings allowed us to conclude that the occlusion affected the performance accuracy but the control strategy to intercepting seemed to be similar in both conditions.KeywordMotor controlFeedback mechanismInterceptive task
The use of electroencephalography (EEG) signals for biometrics purposes has gained attention in the last few years, and many works have already shown that it is possible to identify a person based on features extracted from these signals. In this work we focus on four functional connectivity measures (magnitude-squared and imaginary coherence, motif synchronization and space-time recurrence) for the classification of 10 epilepsy patients with recorded resting-state EEG signals, to compare and discuss different methodologies. We perform the analysis by slicing the signals of at least 2 trials for each subject in epochs of 3 and 10 s, filtering the data in the ranges of 1 40 Hz and 1 100 Hz, building reference and test vectors from the connectivity measures and labeling each test vector to a subject using the minimal Euclidean distance from the feature vectors. The best classification rates were obtained with magnitude-squared coherence and motif synchronization, for the data segmented in epochs of 10 s and filtered between 1 40 Hz. All the measures with the signal filtered in the same range obtained an accuracy equal or higher than \(80\%\), a result that can be enhanced with more complex classifiers.KeywordsEEG-based biometryEpilepsyBrain connectivity
High-density Electroencephalography (HD-EEG) has proven to be the EEG montage that estimates the neural activity inside the brain with highest accuracy. Multiple studies have reported the effect of electrode number on source localization for specific sources and specific electrode configurations. The electrodes for these configurations are often manually selected to uniformly cover the entire head, going from 32 to 128 electrodes, but electrode configurations are not often selected according to their contribution to estimation accuracy. In this work, an optimization-based study is proposed to determine the minimum number of electrodes that can be used and to identify the optimal combinations of electrodes that can retain the localization accuracy of HD-EEG reconstructions. This optimization approach incorporates scalp landmark positions of widely used EEG montages. In this way, a systematic search for the minimum electrode subset is performed for single- and multiple-source localization problems. The Non-dominated Sorting Genetic Algorithm II (NSGA-II) combined with source reconstruction methods is used to formulate a multi-objective optimization problem that concurrently minimizes (1) the localization error for each source and (2) the number of required EEG electrodes. The method can be used for evaluating the source localization quality of low-density EEG systems (e.g. consumer-grade wearable EEG). We performed an evaluation over synthetic and real EEG datasets with known ground-truth. The experimental results show that optimal subsets with 6 electrodes can attain an equal or better accuracy than HD-EEG (with more than 200 channels) for a single source case. This happened when reconstructing a particular brain activity in more than 88% of the cases in synthetic signals and 63% in real signals, and in more than 88% and 73% of cases when considering optimal combinations with 8 channels. For a multiple-source case of three sources (only with synthetic signals), it was found that optimized combinations of 8, 12 and 16 electrodes attained an equal or better accuracy than HD-EEG with 231 electrodes in at least 58%, 76%, and 82% of cases respectively. Additionally, for such electrode numbers, lower mean errors and standard deviations than with 231 electrodes were obtained.
Background:
Decentralized health systems in Low and Middle-Income Countries (LMICs) impacted by humanitarian crises lack resources and a qualified workforce to attend to the overwhelming demand for mental health care in emergencies. Innovative approaches that are safe, cost-effective, and scalable are needed to address the burden of traumatic stress brought by emergencies. High mobile phone ownership rates combined with the precision of neural, cognitive, and biometric measures of trauma and its feasible integration with Artificial Intelligence (AI) makes digital application (app) interventions a promising pathway to promote precision diagnosis and high-impact care.
Objective:
The aims of this study are to advance methods for the objective diagnosis and treatment of trauma in emergencies across LMICs by examining (i) neural, cognitive, and biometric markers and (ii) the efficacy of the eResilience App, a neuroscience-informed mobile health mental health app intervention, via changes in clinical symptomatology, cognitive performance, and brain activity.
Methods:
Trauma-exposed African refugees residing in Australia were selected for this study. A research software version of the eResilience App with advanced monitoring capabilities was designed for the trial. Participants completed the eResilience App at home during a seven-day period. Clinical, cognitive, and electrophysiological data were collected during baseline and post-test to examine biomarkers of trauma and the efficacy of the proposed digital intervention for the treatment of trauma and its potential outcomes including depression, anxiety, physical symptoms, self-harm, substance misuse, and cognitive impairment. In addition, biofeedback, wellbeing, and subjective stress data points were collected via the app during the treatment week, followed by clinical interviews at 1, 3, 6 and 12-months post-intervention.
Results:
Data collection was conducted between 2018 and 2020. A total n=100 participants exposed to war were screened, n= 75 were enrolled and assigned to a trauma-exposed control (n=38) or Posttraumatic Stress Disorder (PTSD) condition (n=37), and n= 70 completed all baseline, treatment, and post-test assessments. A total n=62 of the n=70 who completed the intervention opted to enrol in the 3, 6 and 12-month follow-ups. Data collection is complete, and results are being prepared for publication. If proven efficacious, this proof-of-concept clinical trial will inform fully powered randomized clinical trials in LMICs to further develop AI-powered, app-based diagnostic and prognostic features, and determine the app's cross-cultural efficacy for the treatment of trauma in emergency settings.
Conclusions:
This protocol provides researchers with a comprehensive background of the study rationale, a detailed guideline for replication studies interested in examining the feasibility and the efficacy of the eResilience App across varied demographics, and a robust framework for investigations of low-cost objective diagnostic markers in mental health interventions. Methodological limitations and suggestions are also provided.
Clinicaltrial:
Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12616001205426. Universal Trial Number (UTN): U1111-1180-0347.
Cognitive control/executive function (EF) and attention deficits are prevalent among students and impact comprehension performance. While EF and attention impairments are well-studied, the interaction between cognitive control/EF, attention, arousal/engagement, and comprehension has yet to be explored. Undergraduates' ADHD symptoms, cognitive abilities, and cognitive control were assessed prior to listening to passages of varying degrees of emotional valence and responding to comprehension questions. Exploratory EEG data were also collected to examine patterns of cognitive engagement/emotional arousal. Results showed that comprehension for participants with high numbers of ADHD symptoms and/or proactive cognitive control types were influenced by the emotional valence of the context. In emotional contexts, those with high ADHD symptoms showed better comprehension overall and deep levels of processing, and those with proactive cognitive control types showed better deep processing. These findings indicate the need for further research to tease apart the interaction of EF, attention, and arousal on comprehension across different contexts.
The digitalization process for organizations, which was inevitably accelerated by the COVID-19 pandemic, raises relevant challenges for Human Resource Management (HRM) because every technological implementation has a certain impact on human beings. Between many organizational HRM practices, recruitment and assessment interviews represent a significant moment where a social interaction provides the context for evaluating candidates’ skills. It is therefore relevant to investigate how different interaction frames and relational conditions affect such task, with a specific focus on the differences between face-to-face (FTF) and remote computer-mediated (RCM) interaction settings. In particular, the possibility of qualifying and quantifying the mechanisms shaping the efficiency of interaction in the recruiter-candidate dyad—i.e. interpersonal attunement—is potentially insightful. We here present a neuroscientific protocol aimed at elucidating the impact of FTF vs. RCM modalities on social dynamics within assessment interviews. Specifically, the hyperscanning approach, understood as the concurrent recording and integrated analysis of behavioural-physiological responses of interacting agents, will be used to evaluate recruiter-candidate dyads while they are involved in either FTF or RCM conditions. Specifically, the protocol has been designed to collect self-report, oculometric, autonomic (electrodermal activity, heart rate, heart rate variability), and neurophysiological (electroencephalography) metrics from both inter-agents to explore the perceived quality of the interaction, automatic visual-attentional patterns of inter-agents, as well as their cognitive workload and emotional engagement. The proposed protocol will provide a theoretical evidence-based framework to assess possible differences between FTF vs. RMC settings in complex social interactions, with a specific focus on job interviews.
High-density Electroencephalography (HD-EEG) has been proven to be the most accurate option to estimate the neural activity inside the brain. Multiple studies report the effect of electrode number on source localization for specific sources and specific electrode configurations. The electrodes for these configurations have been manually selected to uniformly cover the entire head, going from 32 to 128 electrodes, but electrodes were not selected according to their contribution to accuracy. In this work, an optimization-based study is proposed to determine the minimum number of electrodes and identify optimal combinations of electrodes that can retain the localization accuracy of HD-EEG reconstructions. This optimization approach incorporates scalp landmark positions of widely used EEG montages. In this way, a systematic search for the minimum electrode subset is performed for single and multiple source localization problems. The Non-dominated Sorting Genetic Algorithm II (NSGA-II) combined with source reconstruction methods is used to formulate a multi-objective optimization problem that concurrently minimizes 1) the localization error for each source and 2) the number of required EEG electrodes. The method can be used for evaluating the source localization quality of low-density EEG systems (e.g. consumer-grade wearable EEG). We performed an evaluation over synthetic and real EEG dataset with known ground-truth. The experimental results show that optimal subsets with 6 electrodes can obtain an equal or better accuracy than HD-EEG (with more than 200 channels) for a single source case. This happened when reconstructing a particular brain activity in more than 88% of the cases (in synthetic signals) and 63% (in real signals), and in more than 88% and 73% of the cases when considering optimal combinations with 8 channels. For a multiple-source case of three sources (only with synthetic signals), it was found that optimized combinations of 8, 12 and 16 electrodes attained an equal or better accuracy than HD-EEG with 231 electrodes in at least 58%, 76%, and 82% of the cases respectively. Additionally, for such electrode numbers, a lower mean error and standard deviation than with 231 electrodes were obtained.
Highlights
The number of EEG electrodes and their locations can be optimized for reconstructing the brain source activity.
Optimally selected EEG electrodes can retain the accuracy of high density montages (256, 128 chs) for brain source estimation, when electrodes are selected according to their contribution to accuracy.
With optimization, selected combinations of EEG electrodes will flexibilize the estimation of the source activity.
Approach and avoidance tendencies play an important role in everyday food choices when choosing between high-caloric, rather unhealthy, and low-caloric, rather healthy options. On a neuronal level, approach and avoidance motivation have been associated with asymmetrical activity of the frontal cortex, often quantified by alpha power averaged over several seconds of resting electroencephalogram (EEG). Going beyond the analysis of resting EEG, the present study aimed to investigate asymmetrical frontal activity in direct response to food stimuli in an event-related design and in combination with event-related potentials (ERPs). Therefore, a sample of 56 young and healthy participants completed a food choice task. They were asked to choose from a selection of high-caloric and low-caloric foods which they would want to eat on a normal day (baseline), when being on a diet, and in a reward situation. On the behavioural level, there was a clear preference for low-caloric foods. Well in line with that, time-frequency analyses of alpha asymmetry revealed relatively stronger temporary (950-1175 ms) left-hemispheric frontal activity, that is, a stronger approach tendency, in response to low-caloric as compared to high-caloric foods. Furthermore, larger P300 for low-caloric foods indicated an increased task relevance of low-caloric foods in the baseline and the reward situation. In contrast, the late positive potential (LPP), an index of subjective value, was larger for high- as compared to low-caloric foods, reflecting the intrinsic rewarding properties of high-caloric foods. ERPs, but not frontal alpha asymmetry, were influenced by the situational context.
This paper articulates an innovative systems dynamics model of learning based on a predictive cognitive architecture by interrelating six modules: knowledge, affect, cognition, performance, external agents, and context. To test aspects of this model, this paper focuses on cognitive load theory predicting that a manipulation of the learning task can affect at least one of the three types of load (intrinsic, germane and extraneous). More precisely, agency is hypothesized to affect either the intrinsic or extraneous load. Therefore, the goal of this paper is to explore the effect of agency on cognitive load. Thirty-six dyads (1 player and 1 watcher) played a serious game for learning physics for 120 min while dual-EEG was recorded for all participants. Results of time series analysis show that agency (being a player or a watcher) as no effect on the overall cognitive load when the comparison is made either by group (all players versus all watchers), or within a single dyad. Moreover, nor did agency affect instantaneous cognitive load for a vast majority of dyads. Indeed, only four dyads exhibited one or two significant cross-correlations. However, those exceptional cases cannot be generalized. Finer-grained analyses are proposed in the discussion to better explore the role of agency on cognitive load in further research.
Startle stimuli evoke lower responses when presented during the early as compared to the
late cardiac cycle phase, an effect that has been called ‘cardiac modulation of startle’ (CMS). The CMS effect may be associated with visceral-afferent neural traffic, as it is reduced in individuals with degeneration of afferent autonomic nerves. The aim of this study was to investigate whether the CMS effect is due a modulation of only early, automatic stages of stimulus processing by baro-afferent neural traffic, or if late stages are also affected. We, therefore, investigated early and late components of auditory-evoked potentials (AEPs) to acoustic startle stimuli (105, 100, 95 dB), which were presented during the early (R-wave +230 ms) or the late cardiac cycle phase (R +530 ms) in two studies. In Study 1, participants were requested to ignore (n=25) or to respond to the stimuli with button-presses (n=24). In Study 2 (n=23), participants were asked to rate the intensity of the stimuli. We found lower EMG startle response magnitudes (both studies) and slower pre-motor reaction times in the early as compared to the late cardiac cycle phase (Study 1). We also observed lower N1 negativity (both studies), but higher P2 (Study 1) and P3 positivity (both studies) in response to stimuli presented in the early cardiac cycle phase. This AEP modulation pattern appears to be specific to the CMS effect, suggesting that early stages of startle stimulus processing are attenuated, whereas late stages are enhanced by baro-afferent neural traffic.
An important goal in Brain-Computer Interfacing (BCI) is to find and enhance procedural strategies for users for whom BCI control is not sufficiently accurate. To address this challenge, we conducted offline analyses and online experiments to test whether the classification of different types of motor imagery could be improved when the training of the classifier was performed on the data obtained with the assistive muscular stimulation below the motor threshold. 10 healthy participants underwent three different types of experimental conditions: a) Motor imagery (MI) of hands and feet b) sensory threshold neuromuscular electrical stimulation (STM) of hands and feet while resting and c) sensory threshold neuromuscular electrical stimulation during performance of motor imagery (BOTH). Also, another group of 10 participants underwent conditions a) and c). Then, online experiments with 15 users were performed. These subjects received neurofeedback during MI using classifiers calibrated either on MI or BOTH data recorded in the same experiment. Offline analyses showed that decoding MI alone using a classifier based on BOTH resulted in a better BCI accuracy compared to using a classifier based on MI alone. Online experiments confirmed accuracy improvement of MI alone being decoded with the classifier trained on BOTH data. In addition, we observed that the performance in MI condition could be predicted on the basis of a more pronounced connectivity within sensorimotor areas in the frequency bands providing the best performance in BOTH. These finding might offer a new avenue for training SMR-based BCI systems particularly for users having difficulties to achieve efficient BCI control. It might also be an alternative strategy for users who cannot perform real movements but still have remaining afferent pathways (e.g., ALS and stroke patients).
The present study investigated a recently introduced left-lateralized component in the event-related potential (ERP), the posterior semantic asymmetry (PSA), in the context of an isolation paradigm. The PSA is a relative negativity that is most pronounced at temporoparietal electrodes, peaks around 300 ms, and is assumed to reflect early semantic processing of visual words. A free-recall, word-list-learning paradigm was conducted. The learning list comprised two stimuli which were physically isolated from the other stimuli (by different font size or different typeface). The typical behavioral isolation effect with higher recall for isolated stimuli was observed. Furthermore, ERP effects of stimulus type and subsequent memory were analyzed. A left-lateralized negativity that matched the topography of the PSA but occurred somewhat later showed an effect of stimulus distinctiveness, with increased amplitudes for isolates, thus suggesting their deeper semantic processing. However, PSA amplitude did not predict subsequent recall. Unlateralized ERPs replicated previous findings of a greater late frontal positivity during elaborated encoding of both isolated stimuli and subsequently recalled stimuli. This recall effect was greater for isolated than standard stimuli. We argue that physical distinctiveness during encoding facilitates recall to the extent that it promotes the frontally-mediated processes that predict better recall in general.
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