A scoping review on the use of consumer-grade EEG devices for research.

BACKGROUND: Commercial electroencephalography (EEG) devices have become increasingly available over the last decade. These devices have been used in a wide variety of fields ranging from engineering to cognitive neuroscience. PURPOSE: The aim of this study was to chart peer-review articles that used consumer-grade EEG devices to collect neural data. We provide an overview of the research conducted with these relatively more affordable and user-friendly devices. We also inform future research by exploring the current and potential scope of consumer-grade EEG. METHODS: We followed a five-stage methodological framework for a scoping review that included a systematic search using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines. We searched the following online databases: PsycINFO, MEDLINE, Embase, Web of Science, and IEEE Xplore. We charted study data according to application (BCI, experimental research, validation, signal processing, and clinical) and location of use as indexed by the first author's country. RESULTS: We identified 916 studies that used data recorded with consumer-grade EEG: 531 were reported in journal articles and 385 in conference papers. Emotiv devices were used most, followed by the NeuroSky MindWave, OpenBCI, interaXon Muse, and MyndPlay Mindband. The most common usage was for brain-computer interfaces, followed by experimental research, signal processing, validation, and clinical purposes. CONCLUSIONS: Consumer-grade EEG is a useful tool for neuroscientific research and will likely continue to be used well into the future. Our study provides a comprehensive review of their application, as well as future directions for researchers who plan to use these devices.

It's all about time: precision and accuracy of Emotiv event-marking for ERP research.

BACKGROUND: The use of consumer-grade electroencephalography (EEG) systems for research purposes has become more prevalent. In event-related potential (ERP) research, it is critical that these systems have precise and accurate timing. The aim of the current study was to investigate the timing reliability of event-marking solutions used with Emotiv commercial EEG systems. METHOD: We conducted three experiments. In Experiment 1 we established a jitter threshold (i.e. the point at which jitter made an event-marking method unreliable). To do this, we introduced statistical noise to the temporal position of event-marks of a pre-existing ERP dataset (recorded with a research-grade system, Neuroscan SynAmps2 at 1,000 Hz using parallel-port event-marking) and calculated the level at which the waveform peaks differed statistically from the original waveform. In Experiment 2 we established a method to identify 'true' events (i.e. when an event should appear in the EEG data). We did this by inserting 1,000 events into Neuroscan data using a custom-built event-marking system, the 'Airmarker', which marks events by triggering voltage spikes in two EEG channels. We used the lag between Airmarker events and events generated by Neuroscan as a reference for comparisons in Experiment 3. In Experiment 3 we measured the precision and accuracy of three types of Emotiv event-marking by generating 1,000 events, 1 s apart. We measured precision as the variability (standard deviation in ms) of Emotiv events and accuracy as the mean difference between Emotiv events and true events. The three triggering methods we tested were: (1) Parallel-port-generated TTL triggers; (2) Arduino-generated TTL triggers; and (3) Serial-port triggers. In Methods 1 and 2 we used an auxiliary device, Emotiv Extender, to incorporate triggers into the EEG data. We tested these event-marking methods across three configurations of Emotiv EEG systems: (1) Emotiv EPOC+ sampling at 128 Hz; (2) Emotiv EPOC+ sampling at 256 Hz; and (3) Emotiv EPOC Flex sampling at 128 Hz. RESULTS: In Experiment 1 we found that the smaller P1 and N1 peaks were attenuated at lower levels of jitter relative to the larger P2 peak (21 ms, 16 ms, and 45 ms for P1, N1, and P2, respectively). In Experiment 2, we found an average lag of 30.96 ms for Airmarker events relative to Neuroscan events. In Experiment 3, we found some lag in all configurations. However, all configurations exhibited precision of less than a single sample, with serial-port-marking the most precise when paired with EPOC+ sampling at 256 Hz. CONCLUSION: All Emotiv event-marking methods and configurations that we tested were precise enough for ERP research as the precision of each method would provide ERP waveforms statistically equivalent to a research-standard system. Though all systems exhibited some level of inaccuracy, researchers could easily account for these during data processing.

The effect of an integrated reading and anxiety intervention for poor readers with anxiety.

A recent systematic review has reported that poor reading is reliably associated with anxiety. However, we currently lack evidence-based intervention for children who have both poor reading and anxiety (PRAX). In this study, we tested a new PRAX intervention in 8- to 12-year-old children using a double-baseline intervention case series design. Analyses of both group and individual data revealed that 12 weeks of PRAX intervention significantly improved children's reading and spelling accuracy, and significantly reduced both anxiety disorders and symptoms. These results support PRAX intervention as a treatment for comorbid reading and anxiety problems in children and pave the way to a randomised controlled trial.

Self-concept in poor readers: a systematic review and meta-analysis.

BACKGROUND: The aims of this systematic review and meta-analyses were to determine if there is a statistically reliable association between poor reading and poor self-concept, and if such an association is moderated by domain of self-concept, type of reading impairment, or contextual factors including age, gender, reading instruction, and school environment. METHODOLOGY: We searched 10 key databases for published and unpublished studies, as well as reference lists of included studies, and studies that cited included studies. We calculated standardised mean differences (SMDs) and 95% confidence intervals for one primary outcome (average self-concept) and 10 secondary outcomes (10 domains of self-concept). We assessed the data for risk of bias, heterogeneity, sensitivity, reporting bias, and quality of evidence. RESULTS: Thirteen studies with 3,348 participants met our selection criteria. Meta-analyses revealed statistically significant SMDs for average self-concept (-0.57) and five domains of self-concept (reading/writing/spelling: -1.03; academic: -0.67; math: -0.64; behaviour: -0.32; physical appearance: -0.28). The quality of evidence for the primary outcome was moderate, and for secondary outcomes was low, due to lack of data. CONCLUSIONS: These outcomes suggest a probable moderate association between poor reading and average self-concept; a possible strong association between poor reading and reading-writing-spelling self-concept; and possible moderate associations between poor reading and self-concept in the self-concept domains of academia, mathematics, behaviour, and physical appearance.

A validation of Emotiv EPOC Flex saline for EEG and ERP research.

BACKGROUND: Previous work has validated consumer-grade electroencephalography (EEG) systems for use in research. Systems in this class are cost-effective and easy to set up and can facilitate neuroscience outside of the laboratory. The aim of the current study was to determine if a new consumer-grade system, the Emotiv EPOC Saline Flex, was capable of capturing research-quality data. METHOD: The Emotiv system was used simultaneously with a research-grade EEG system, Neuroscan Synamps2, to collect EEG data across 16 channels during five well-established paradigms: (1) a mismatch negativity (MMN) paradigm that involved a passive listening task in which rare deviant (1,500 Hz) tones were interspersed amongst frequent standard tones (1,000 Hz), with instructions to ignore the tones while watching a silent movie; (2) a P300 paradigm that involved an active listening task in which participants were asked to count rare deviant tones presented amongst frequent standard tones; (3) an N170 paradigm in which participants were shown images of faces and watches and asked to indicate whether the images were upright or inverted; (4) a steady-state visual evoked potential (SSVEP) paradigm in which participants passively viewed a flickering screen (15 Hz) for 2 min; and (5) a resting state paradigm in which participants sat quietly with their eyes open and then closed for 3 min each. RESULTS: The MMN components and P300 peaks were equivalent between the two systems (BF10 = 0.25 and BF10 = 0.26, respectively), with high intraclass correlations (ICCs) between the ERP waveforms (>0.81). Although the N170 peak values recorded by the two systems were different (BF10 = 35.88), ICCs demonstrated that the N170 ERP waveforms were strongly correlated over the right hemisphere (P8; 0.87-0.97), and moderately-to-strongly correlated over the left hemisphere (P7; 0.52-0.84). For the SSVEP, the signal-to-noise ratio (SNR) was larger for Neuroscan than Emotiv EPOC Flex (19.94 vs. 8.98, BF10 = 51,764), but SNR z-scores indicated a significant brain response at the stimulus frequency for both Neuroscan (z = 12.47) and Flex (z = 11.22). In the resting state task, both systems measured similar alpha power (BF10 = 0.28) and higher alpha power when the eyes were closed than open (BF10 = 32.27). CONCLUSIONS: The saline version of the Emotiv EPOC Flex captures data similar to that of a research-grade EEG system. It can be used to measure reliable auditory and visual research-quality ERPs. In addition, it can index SSVEP signatures and is sensitive to changes in alpha oscillations.

Auditory processing disorders: can they be treated?

PURPOSE OF REVIEW: In recent years, parents and schools have spent millions of pounds and dollars on commercial programs that claim to treat children's developmental disorders by training their auditory processing. Here I test the truth of this claim using evidence from recent auditory training studies done with children with developmental disorders. RECENT FINDINGS: Six studies were published in 2007 and 2008 that trained children with developmental disorders on an auditory training program that included nonspeech sounds or simple speech sounds. The results suggest that nonspeech training and simple speech training can treat children's auditory processing disorders. However, this training has little or no effect on their reading, spoken language, or attention. SUMMARY: This conclusion suggests that commercial training programs could increase their efficiency (and decrease their cost) by removing redundant nonspeech and simple speech training components. The dearth of well controlled auditory training studies, paired with the misleading nature of poorly controlled studies, suggests that we need to teach parents, teachers, and the media how to separate the good training studies from the bad ones.

The association between poor reading and internalising problems: A systematic review and meta-analysis.

Numerous studies have demonstrated an association between learning disabilities and internalising problems such as anxiety and depression. However, our understanding of this association for people with specific types of learning disability - such as poor reading - is poorly understood. Here, we present the first systematic review and meta-analysis of studies that have examined associations between poor reading and internalising problems - including anxiety and depression - in children, adolescents, and adults. Our systematic search identified 34 studies comprising 16,275 participants (N = 2491 poor readers). Our meta-analysis revealed statistically significant differences between poor readers and typical readers on general measures of internalising problems (d = 0.41), as well as specific measures of anxiety (d = 0.41) and depression (d = 0.23). These outcomes suggest that poor readers are at moderate risk for experiencing internalising problems compared to typical readers, which appears to stem from a greater risk for anxiety than depression.

Is discrimination training necessary to cause changes in the P2 auditory event-related brain potential to speech sounds?

Previous studies have found that the P2 component of the auditory event-related potential (ERP) increases after speech discrimination training. We compared electrophysiological and behavioral outcomes of individuals undergoing speech discrimination training (N = 8) with an untrained control group (N = 9). Significant improvements on the behavioral speech discrimination task were found only in the trained group; however, there were similar increases in P2 amplitude in both groups. Simple exposure to repeated instances of a speech sound during the ERP recording seems sufficient lead to enhancement of P2. This interpretation was bolstered by the finding of significant change in P2 during the first and second halves of the initial ERP recording, when listeners were not required to make any discriminative response. However, the largest change in P2 occurred between rather than within recording sessions, suggesting that the effects of exposure to a speech stimulus on ERPs may have a slow time-course and are most evident after a delay. Our data challenge the view that increased P2 amplitude reflects enhanced perceptual discrimination by auditory cortex.

Individual differences in auditory processing in specific language impairment: a follow-up study using event-related potentials and behavioural thresholds.

It has frequently been claimed that children with specific language impairment (SLI) have impaired auditory perception, but there is much controversy about the role of such deficits in causing their language problems, and it has been difficult to establish solid, replicable findings in this area. Discrepancies in this field may arise because (a) a focus on mean results obscures the heterogeneity in the population and (b) insufficient attention has been paid to maturational aspects of auditory processing. We conducted a study of 16 young people with specific language impairment (SLI) and 16 control participants, 24 of whom had had auditory event-related potentials (ERPs) and frequency discrimination thresholds assessed 18 months previously. When originally assessed, around one third of the listeners with SLI had poor behavioural frequency discrimination thresholds, and these tended to be the younger participants. However, most of the SLI group had age-inappropriate late components of the auditory ERP, regardless of their frequency discrimination. At follow-up, the behavioural thresholds of those with poor frequency discrimination improved, though some remained outside the control range. At follow-up, ERPs for many of the individuals in the SLI group were still not age-appropriate. In several cases, waveforms of individuals in the SLI group resembled those of younger typically-developing children, though in other cases the waveform was unlike that of control cases at any age. Electrophysiological methods may reveal underlying immaturity or other abnormality of auditory processing even when behavioural thresholds look normal. This study emphasises the variability seen in SLI, and the importance of studying individual cases rather than focusing on group means.

Phonological categorization of vowels: a mismatch negativity study.

There is electrophysiological evidence that phonological categorization has occurred within 100-200 ms post stimulus onset for the syllables /tae/ and /dae/, which vary in voice onset time. Using a similar paradigm, this study investigated when phonological categorization occurred for the contrast between /I/ and /epsilon/, using synthesized speech tokens that differed in the frequency of the first formant. Here we show that phonological categorization of these tokens has not occurred 100-200 ms after stimulus onset. However, the presence of a late mismatch negativity (350 ms after stimulus onset) indicated that phonological categorization had taken place by this time.

Can training normalize atypical passive auditory ERPs in children with SRD or SLI?

This study tested if training can normalize atypical passive auditory event-related potentials in the N1-P2 time window in children with specific reading disability (SRD) or specific language impairment (SLI). Children with SRD or SLI and untrained controls were tested for their behavioral responses and N1-P2 windows to tones, backward-masked tones, vowels, and consonant-vowels. Children with SRD or SLI with poor behavioral responses to one of these sounds trained to discriminate that sound for 30 minutes a day, 4 days a week, for 6 weeks. Post-training measures revealed that training normalized atypical behavioral responses but not atypical N1-P2 windows.