Brain-computer interface research comes of age: traditional assumptions meet emerging realities

Brain-computer interfaces (BCIs) could provide important new communication and control options for people with severe motor disabilities. Most BCI research to date has been based on 4 assumptions that: (a) intended actions are fully represented in the cerebral cortex; (b) neuronal action potentials can provide the best picture of an intended action; (c) the best BCI is one that records action potentials and decodes them; and (d) ongoing mutual adaptation by the BCI user and the BCI system is not very important. In reality, none of these assumptions is presently defensible. Intended actions are the products of many areas, from the cortex to the spinal cord, and the contributions of each area change continually as the CNS adapts to optimize performance. BCIs must track and guide these adaptations if they are to achieve and maintain good performance. Furthermore, it is not yet clear which category of brain signals will prove most effective for BCI applications. In human studies to date, low-resolution electroencephalography-based BCIs perform as well as high-resolution cortical neuron-based BCIs. In sum, BCIs allow their users to develop new skills in which the users control brain signals rather than muscles. Thus, the central task of BCI research is to determine which brain signals users can best control, to maximize that control, and to translate it accurately and reliably into actions that accomplish the users' intentions.     

Brainwave classification without the help of limb movement and any stimulus for character-writing application

Recently, Brain-Computer Interfaces (BCIs) have been extensively popular for employing Electroencephalography (EEG) signals to control devices with different applications. The use of BCIs currently involves for lots of applications to help the disabilities who cannot communicate with other people, as it is an alternative way for communication by passing the need of speech. Although the applications to spell the character with BCI systems (e.g., P300-speller, SSVEP-speller, Hex-O-spell) have been already developed, but these techniques are not flexible in the real scenarios because they require the stimulus all the time or stopping the activity to focus on the limb movement in order to provide the accuracy of brain responses. In this paper, the feasibility of brainwave classification for the applications of character-writing by considering only the EEG signals without the need of stimulus unlike the literature is newly introduced. This paper adopts a classification technique named Artificial Neural Network (ANN) and focuses on two different characters; straight line and circle. From the experimental results, the suitable position of electrodes are the pair of electrodes (F3 and F4) at the frontal lobe, which provide the best result as compared to other areas due to its important role in perception, maintenance and revival of the information. The experimental results indicate that the classification accuracy of the proposed technique is about 70%, which in turn leads to a significant achievement for the development of character-writing applications.     

基于自发脑电的脑机接口研究进展

脑机接口是一种不依赖于外周神经和肌肉等常规输出通道的信息交流系统,近年来发展非常迅速。它可为神经肌肉障碍患者提供一条与外界沟通的途径,并在虚拟现实、游戏娱乐和航空等领域具有潜在价值。目前,脑机接口中常用的脑电输入信号包括P300、稳态视觉诱发电位（SS—VEP）、皮层慢电位（SCP）以及μ或β节律等。其中,SCP、μ或β节律等自发脑电不依赖于额外刺激的输入,不会产生视觉疲劳,没有适应性的问题,且其神经生理学基础已获得比较深入的研究,因而在脑机接口中得到了较多的应用。但是,基于自发脑电的脑机接口也存在明显的缺陷,如并非所有个体都适用基于汕节律的脑机接口,基于SCP的脑机接口要经过长时间的训练才能实现等。     

Embodiment and Estrangement: Results from a First-in-Human “Intelligent BCI” Trial

While new generations of implantable brain computer interface (BCI) devices are being developed, evidence in the literature about their impact on the patient experience is lagging. In this article, we address this knowledge gap by analysing data from the first-in-human clinical trial to study patients with implanted BCI advisory devices. We explored perceptions of self-change across six patients who volunteered to be implanted with artificially intelligent BCI devices. We used qualitative methodological tools grounded in phenomenology to conduct in-depth, semi-structured interviews. Results show that, on the one hand, BCIs can positively increase a sense of the self and control; on the other hand, they can induce radical distress, feelings of loss of control, and a rupture of patient identity. We conclude by offering suggestions for the proactive creation of preparedness protocols specific to intelligent—predictive and advisory—BCI technologies essential to prevent potential iatrogenic harms.

     

Alcohol Counseling in Hospital Trauma: Examining Two Brief Interventions

Hospital trauma centers intervene with patients who incur alcohol‐related injuries. This prospective study, using professional counselors and trainees, investigated brief counseling interventions (BCIs). Participants were randomized to either a conventional BCI examining quantity and frequency of drinks or a personalized BCI exploring overintoxication. No statistically significant difference between risky drinkers randomized to either intervention in a hospital trauma center was observed. Findings indicate that a personalized BCI may be an alternative to a quantitative BCI in reducing risky alcohol consumption.     

Effect of mindfulness meditation on brain–computer interface performance

Electroencephalogram based brain–computer interfaces (BCIs) enable stroke and motor neuron disease patients to communicate and control devices. Mindfulness meditation has been claimed to enhance metacognitive regulation. The current study explores whether mindfulness meditation training can thus improve the performance of BCI users. To eliminate the possibility of expectation of improvement influencing the results, we introduced a music training condition. A norming study found that both meditation and music interventions elicited clear expectations for improvement on the BCI task, with the strength of expectation being closely matched. In the main 12 week intervention study, seventy-six healthy volunteers were randomly assigned to three groups: a meditation training group; a music training group; and a no treatment control group. The mindfulness meditation training group obtained a significantly higher BCI accuracy compared to both the music training and no-treatment control groups after the intervention, indicating effects of meditation above and beyond expectancy effects.     

Decision making and the P300 component of the cortical evoked response

The amplitude of P300, and of other components of the evoked potentials, was examined during a task which required Ss to make a response appropriate to the conjoint properties of two rapidly successive visual patterns. In one set of conditions, the task was structured such that both stimuli were needed for the choice judgment. In another set of conditions, the task was changed from choice to simple RT by presenting the patterns in a predictable order. It was observed that P300 was enhanced during the choice RT conditions and that this enhancement was present only for the P300 following the stimulus permitting the choice and not the other, relevant but not decisive, stimulus appearing in close temporal proximity. An appreciable degree of independence between P300 and other components was indicated by the appearance of P300 under conditions in which other evoked potential components were entirely refractory. The data support an account for P300 in terms of poststimulus processes, such as decision making, and not in terms of preparatory adjustments.     

An optimized facial stimuli paradigm for hybrid SSVEP+P300 brain computer interface

In this paper, hybrid BCI that merges Event Related Potentials (P300) and Steady State visual Evoked Potentials (SSVEP) simultaneously is proposed to enhance the performance of Four-choice command system. Here we integrate human facial structure in external visual stimulus to evoke stronger cortical responses in hybrid SSVEP+P300 BCI & compare it with non-face stimuli. We also addressed question of feasibility of eliciting one potential by face & other by non-face stimuli. To evoke SSVEP & P300 responses, paradigms with non-face stimuli, neutral face stimuli, and facial expression changes stimuli are proposed. We also projected additional paradigm where SSVEP is elicited by non-face and P300 by flashing different facial expressions. Results proved the last paradigm evoke stronger cortical potentials and thereby improve system accuracy and ITR than other paradigms. Author discussed external stimulus parameters that might affect simultaneous evocation of multiple brain potentials and their deterioration effect on individual potentials.     

测谎中反馈加工的认知神经机制：一项ERP研究

在一个模拟“杀人——侦探”游戏情境中,被试先完成模拟杀人任务,在随后的测谎阶段使用有反馈的ERP测谎范式,以反馈的形式告知被试测谎结果（“+0.5”或“-2”,分别代表“撒谎逃过检测”或“撒谎被发现”）时的脑内时程动态变化。结果发现,在反馈出现后的200～300ms时间段,表示“撒谎被抓住”比“撒谎逃过检测”的反馈信息诱发了一个更正性的ERP成分（P200-300）,在300～400ms时间段,两种反馈诱发的ERP成分（P300）没有差异,而在450～500ms时间段, “撒谎逃过检测”比“撒谎被抓住”的反馈信息诱发了一个更负性的ERP成分（N500）,负性反馈没有诱发FRN。这些结果表明：P200-300、P300和N500都是与加工测谎结果信息有关的ERP成分。P200-300可能对测谎结果的效价（正性或负性）敏感;P300可能反映被试对测谎结果主观意义大小的评价;而N500可能反映测谎结果所导致的大脑皮层兴奋程度。     

Decision-related cortical potentials during an auditory signal detection task with cued observation intervals.

Cortical-evoked potentials were recorded from human subjects performing an auditory detection task with confidence rating responses. Unlike earlier studies that used similar procedures, the observation interval during which the auditory signal could occur was clearly marked by a visual cue light. By precisely defining the observation interval and, hence, syncrhonizing all perceptual decisions to the evoked potential averaging epoch, it was possible to demonstrate that high-confidence false alarms for accompanied by late-positive P3 components equivalent to those for equally confident hits. Moreover the hit and false alarm evoked potentials were found to covary similarily with variations in confidence rating and to have similar amplitude distributions over the scalp. In a second experiment wherein the signal intensity was increased to make signal presence and signal absence clearly discriminable and the a priori probability of signal presentation was varied from .5 to .9, it was demonstrated that correct rejections can be associated with a P3 component larger than that for hits. Thus it was possible to show, within the signal detection paradigm, how the two major factors of decision confidence and expectancy are reflected in the P3 component of the cortical-evoked potential.     

A PDP-12 system for on-line acquisition of heart rate data

A research program for investigating the responsiveness of infants at high risk for developing schizophrenia is described briefly. Two measures of reactivity to brief auditory stimuli, the evoked heart-rate response and the evoked potential of the brain, are recorded for analysis by the PDP-12 computer. An interface to the PDP-12, called the R peak detector and R-R interval counter, is used for reducing the EKG to R-R intervals, with an accuracy of ± 1 msec. The current usage of the PDP-12 and its IBM-compatible tape transports is discussed, and proposed developments for on-line statistical analyses of the physiological data and real-time control of the experiment are presented.     

Suppression of EEG gamma activity may cause the attentional blink

The attentional blink (AB) is an impairment of attention, which occurs when subjects have to report a target stimulus (T2) following a previous target (T1) with a short delay (up to 600 ms). Theories explaining the AB assume that processing of T2 is more vulnerable to decay or substitution, as long as attention is allocated to T1. Existing models of the AB, however, do not account for the fact that T2 detection accuracy reaches the minimum when T2 is presented after about 300 ms and not immediately following T1. Therefore, a new model is suggested, which is based on chronometrical considerations together with recent neurophysiological findings concerning the relation between the P3 event-related potential and the AB, the interaction between P3 and gamma oscillations, and the significance of the early evoked gamma band response. We hypothesize that suppression of the early gamma response to T2, accompanying the P3 related to T1, causes the AB.     

Detection of P300 waves in single trials by the wavelet transform (WT)

The P300 response is conventionally obtained by averaging the responses to the task-relevant (target) stimuli of the oddball paradigm. However, it is well known that cognitive ERP components show a high variability due to changes of cognitive state during an experimental session. With simple tasks such changes may not be demonstrable by the conventional method of averaging the sweeps chosen according to task-relevance. Therefore, the present work employed a response-based classification procedure to choose the trials containing the P300 component from the whole set of sweeps of an auditory oddball paradigm. For this purpose, the most significant response property reflecting the P300 wave was identified by using the wavelet transform (WT). The application of a 5 octave quadratic B-spline-WT on single sweeps yielded discrete coefficients in each octave with an appropriate time resolution for each frequency range. The main feature indicating a P300 response was the positivity of the 4th delta (0.5-4 Hz) coefficient (310-430 ms) after stimulus onset. The average of selected single sweeps from the whole set of data according to this criterion yielded more enhanced P300 waves compared with the average of the target responses, and the average of the remaining sweeps showed a significantly smaller positivity in the P300 latency range compared with the average of the non-target responses. The combination of sweeps classified according to the task-based and response-based criteria differed significantly. This suggests an influence of changes in cognitive state on the presence of the P300 wave which cannot be assessed by task performance alone.     

ELECTROCORTICAL DIFFERENTIATION OF EVALUATIVE AND NONEVALUATIVE CATEGORIZATIONS

Abstract— The evaluative categorizations that underlie affective and attitudinal judgments have often been equated with non-evaluative categorizations despite the central importance of evaluative processes for survival In the present experiment, a late positive potential (LPP) of the event-related brain potential elicited when participants evaluatively categorized food items as positive or nonpositive was compared with the LPP elicited when participants semantically (i e., nonevaluatively) categorized food items as vegetable or nonvegetable Results revealed that evaluative categorizations evoked an LPP that was relatively larger over the right than the left scalp regions compared with the LPP evoked by nonevaluative categorizations. This finding provides evidence regarding the differences in neural and cognitive processes involved in evaluative and nonevaluative categorizations.     

Externalizing psychopathology and gain-loss feedback in a simulated gambling task: dissociable components of brain response revealed by time-frequency analysis

Externalizing is a broad construct that reflects propensity toward a variety of impulse control problems, including antisocial personality disorder and substance use disorders. Two event-related potential responses known to be reduced among individuals high in externalizing proneness are the P300, which reflects postperceptual processing of a stimulus, and the error-related negativity (ERN), which indexes performance monitoring based on endogenous representations. In the current study, the authors used a simulated gambling task to examine the relation between externalizing proneness and the feedback-related negativity (FRN), a brain response that indexes performance monitoring related to exogenous cues, which is thought to be highly related to the ERN. Time-frequency (TF) analysis was used to disentangle the FRN from the accompanying P300 response to feedback cues by parsing the overall feedback-locked potential into distinctive theta (4-7 Hz) and delta (<3 Hz) TF components. Whereas delta-P300 amplitude was reduced among individuals high in externalizing proneness, theta-FRN response was unrelated to externalizing. These findings suggest that in contrast with previously reported deficits in endogenously based performance monitoring (as indexed by the ERN), individuals prone to externalizing problems show intact monitoring of exogenous cues (as indexed by the FRN). The results also contribute to a growing body of evidence indicating that the P300 is attenuated across a broad range of task conditions in high-externalizing individuals.     

Reaction time and movement time as measures of stimulus evaluation and response processes

Reaction time has been divided into the time to initiate a response (RT) and the time to execute the motor response (MT) in many chronometric studies of intelligence. Our purpose was to determine which cognitive processes are reflected by RT and MT. To accomplish this, the latency of the P300 wave of the event-related potential was recorded concurrently with RT and MT measures in three experiments. P300 latency reflects the duration of stimulus evaluation relatively independently of response processes. In the first experiment, a Sternberg memory task was employed to manipulate stimulus classification requirements. In the second, the subjects' emphasis on either speed or accuracy of responding was examined during a task that also manipulated stimulus evaluation time. In the third experiment, a Stroop-like task was used to examine response processes. RT and P300 latency varied with manipulations of stimulus evaluation time, whereas MT varied with difficulty of motor execution. MT was also affected by stimulus classification processes. Both RT and MT were sensitive to processes involved in response bias and preparation. The possibility that the correlations of RT and MT with measures of intelligence are due to effects on a common stage of information processing cannot be rejected in the light of these results.     

Stage analysis of the reaction process using brain-evoked potentials and reaction time

Summary Motor processes partly determine reaction time (RT) in both choice reaction time and in binary classification tasks. These latter tasks are popular in cognitive psychology because the experimenter believes that he has kept the motor component simple and constant and therefore can attribute changes in RT to perceptual or cognitive processes. In this paper we used the P3 component of the event-related potential (ERP) as a time marker indicating the duration of perceptual and cognitive processes. The latency of this component is believed to reflect stimulus evaluation time independent of response selection and organization time.Two types of tasks were used: a choice-reaction time task and a binary classification task. Signal similarity and S-R compatibility additively affected RT, but only signal similarity affected P3 latency. The number of items in the positive set and response type affected both P3 latency and RT. Relative response frequency changed the bias in the cognitive evaluation of the stimulus, reflected in the latency of the P3 component, and affected RT only if the subjects preset their motor system (indexed by the late CNV). A model was presented which proposes that motor processes may partially overlap with the perceptual and cognitive evaluation of the stimulus. Both ERPs and RT are necessary tools in the study of the relative timing of these processes.     

Psychological variables in the control of brain-computer interfaces

BCI (Brain-Computer Interface) is a system that allows interaction between the human brain and a computer. It is based on analyzing electroencephalographic signals (EEG) and processing them to generate control commands. The study analyzed the possible influence of psychological variables, such as the imaginative kinesthetic capacity and anxiety, in relation to performance in a BCI. All participants (4 male and 19 female students) completed the questionnaires and carried out a session of BCI to control their EEG signals in a virtual setting of a car along a straight road. The group was divided into two subgroups according to their EEG signals or differential responses obtained in the left-right discrimination. Study results showed no significant differences in cognitive variables of imagination or in anxiety. By comparing the degree of participants' BCI control, a new quantitative parameter for comparing performances and making decisions in signal processing was found. The findings, the ongoing research process to refine the control of a BCI, and the interaction of psychological and computer procedures are discussed.     

Multiple trials may yield exaggerated effect size estimates

Published psychological research attempting to support the existence of small and medium effect sizes may not have enough participants to do so accurately, and thus, repeated trials or the use of multiple items may be used in an attempt to obtain significance. Through a series of Monte-Carlo simulations, this article describes the results of multiple trials or items on effect size estimates when the averages and aggregates of a dependent measure are analyzed. The simulations revealed a large increase in observed effect size estimates when the numbers of trials or items in an experiment were increased. Overestimation effects are mitigated by correlations between trials or items, but remain substantial in some cases. Some concepts, such as a P300 wave or a test score, are best defined as a composite of measures. Troubles may arise in more exploratory research where the interrelations among trials or items may not be well described.