Analyzing P300 Distractors for Target Reconstruction

P300-based brain-computer interfaces (BCIs) are often trained per-user and per-application space. Training such models requires ground truth knowledge of target and non-target stimulus categories during model training, which imparts bias into the model. Additionally, not all non-targets are created equal; some may contain visual features that resemble targets or may otherwise be visually salient. Current research has indicated that non-target distractors may elicit attenuated P300 responses based on the perceptual similarity of these distractors to the target category. To minimize this bias, and enable a more nuanced analysis, we use a generalized BCI approach that is fit to neither user nor task. We do not seek to improve the overall accuracy of the BCI with our generalized approach; we instead demonstrate the utility of our approach for identifying target-related image features. When combined with other intelligent agents, such as computer vision systems, the performance of the generalized model equals that of the user-specific models, without any user specific data.Comment: 4 pages, 3 figure

Collaborative Brain-Computer Interface for Human Interest Detection in Complex and Dynamic Settings

Humans can fluidly adapt their interest in complex environments in ways that machines cannot. Here, we lay the groundwork for a real-world system that passively monitors and merges neural correlates of visual interest across team members via Collaborative Brain Computer Interface (cBCI). When group interest is detected and co-registered in time and space, it can be used to model the task relevance of items in a dynamic, natural environment. Previous work in cBCIs focuses on static stimuli, stimulus- or response- locked analyses, and often within-subject and experiment model training. The contributions of this work are twofold. First, we test the utility of cBCI on a scenario that more closely resembles natural conditions, where subjects visually scanned a video for target items in a virtual environment. Second, we use an experiment-agnostic deep learning model to account for the real-world use case where no training set exists that exactly matches the end-users task and circumstances. With our approach we show improved performance as the number of subjects in the cBCI ensemble grows, and the potential to reconstruct ground-truth target occurrence in an otherwise noisy and complex environment.Comment: 6 pages, 6 figure

Psicofisiologia do testemunho ocular

Doutoramento em PsicologiaAs testemunhas oculares são muitas vezes o único meio que temos para aceder à autoria de um crime. Contudo, apesar dos 100 anos de evidência de erros no testemunho ocular, a consciência das suas limitações como meio de prova só ganhou força no advento do ADN. De facto os estudos de exoneração mostraram que 70 % das ilibações estavam associadas a erros de testemunho ocular. Estes erros têm um impacto social elevado principalmente os falsos positivos, por colocar inocentes na prisão. De acordo com a literatura, deverão ser utilizadas novas abordagens para tentar reduzir o numero de erros de identificação. Destas abordagens, destacam-se a análise dos padrões de movimentos oculares e os potenciais evocados. Nos nossos estudos utilizamos essas novas abordagens com o objetivo de examinar os padrões de acerto ou de identificação do criminoso, usando um paradigma de deteção de sinal. No que diz respeito aos movimentos oculares, não foram encontrados padrões robustos de acerto. No entanto, obtiveram-se evidências oculométricas de que a fusão de dois procedimentos (Alinhamento Simultâneo depois de um Alinhamento Sequencial com Regra de Paragem) aumenta a probabilidade de acerto. Em relação aos potenciais evocados, a P100 registou maior amplitude quando identificamos um inocente. Este efeito é concomitante com uma hiperactivação no córtex prefrontal ventromedial (CPFVM) identificada na análise de estimação de fontes. Esta hiperativação poderá estar relacionada com uma exacerbação emocional da informação proveniente da amígdala. A literatura relaciona a hiperativação no CPFVM com as falsas memorias, e estes resultados sugerem que a P100 poderá ser um promissor indicador de falsos positivos. Os resultados da N170 não nos permitem associar este componente ao acerto na identificação. Relativamente à P300, os resultados mostram uma maior amplitude deste componente quando identificamos corretamente um alvo, mas não diferiu significativamente de quando identificamos um inocente. Porém, a estimação de fontes mostrou que nessa janela temporal (300-600 ms) se verifica uma hipoativação dos Campos Oculares Frontais (COF) quando um distrator é identificado. Baixas ativações dos COF estão relacionadas com redução da eficiência de processamento e com a incapacidade para detetar alvos. Nas medidas periféricas, a eletromiografia facial mostrou que a maior ativação do corrugador e a menor ativação do zigomático são um bom indicador de quando estamos perante um criminoso. No que diz respeito ao ritmo cardíaco, a desaceleração esperada para os alvos devido à sua saliência emocional apenas foi obtida quando a visualização de um alvo foi acompanhada por um erro na identificação (i.e., um falso negativo). Neste trabalho de investigação parece que o sistema nervoso periférico está a responder corretamente, identificando o alvo, por ser emocionalmente mais saliente, enquanto que a modulação executiva efectuada pelo CPFVM conduz ao falso positivo. Os resultados obtidos são promissores e relevantes, principalmente quando o resultado de um erro poderá ser uma condenação indevida e, consequentemente, uma vida injustamente destruída.Eyewitnesses are often the only way we can access the author of a crime. However, despite 100 years of evidence of errors in eyewitness testimony, awareness of its limitations only gained strength with the advent of DNA. In fact, 70% of exonerations have been associated with eyewitness errors. These errors have a high social impact, mainly false positives. According to the literature, new approaches to try to reduce the number of identification errors should be used. Of these, the study of oculometric patterns and event-related Potentials (ERP) stand out. In our studies, these new approaches were used with the objective of examining patterns of accuracy, using a signal detection paradigm. Regarding eye movements, no entirely clear patterns were found. However, there was oculometric evidence that the merging of two procedures (Simultaneous Lineup after a Sequential Lineup with Stopping Rule) increases performance accuracy. Regarding ERPs, the P100 registered a larger amplitude when an innocent was identified. This effect is concomitant with a hyperactivation in the ventromedial prefrontal cortex (VMPFC) identified by source estimation analysis. This hyperactivation might be related to an emotional exacerbation of the information coming from the amygdala. The literature relates the hyperactivation in the VMPFC with false memories, and these results suggest that the P100 component might be a promising marker of false positive errors. The results of the N170 do not allow to associate this component with accuracy. Regarding the P300, the results showed a greater amplitude of this component when a target was correctly identified but did not differ significantly from when an innocent was identified. However, source analysis in this time window (300-600 ms) showed a hypoactivation of Frontal Eye Fields (FEF) when a distractor was identified. FEF inactivations are related to the reduction of processing efficiency and to the inability to detect a target. Concerning the peripheral measures, facial electromyography showed that the greater activation of the corrugator and the lower activation of the zygomaticus are a good marker of when we are facing a perpetrator. Regarding heart rate, the expected deceleration for the targets due to their emotional salience was only obtained when the visualization of a target was accompanied by an error in the identification (i.e., a miss). In this research it seems that the peripheral nervous system is responding correctly, identifying the target, because it is emotionally more salient, while the executive modulation carried out by the VMPFC causes the false positive error. The results presently obtained are promising and relevant, especially when the result of an error might be an undue condemnation of an innocent and consequently a destroyed life

Evaluation of Single-Trial Classification to Control a Visual ERP-BCI under a Situation Awareness Scenario.

An event-related potential (ERP)-based brain–computer interface (BCI) can be used to monitor a user’s cognitive state during a surveillance task in a situational awareness context. The present study explores the use of an ERP-BCI for detecting new planes in an air traffic controller (ATC). Two experiments were conducted to evaluate the impact of different visual factors on target detection. Experiment 1 validated the type of stimulus used and the effect of not knowing its appearance location in an ERP-BCI scenario. Experiment 2 evaluated the effect of the size of the target stimulus appearance area and the stimulus salience in an ATC scenario. The main results demonstrate that the size of the plane appearance area had a negative impact on the detection performance and on the amplitude of the P300 component. Future studies should address this issue to improve the performance of an ATC in stimulus detection using an ERP-BCI.Partial funding for open access charge: Universidad de Málag

Decoding Neural Activity to Assess Individual Latent State in Ecologically Valid Contexts

There exist very few ways to isolate cognitive processes, historically defined via highly controlled laboratory studies, in more ecologically valid contexts. Specifically, it remains unclear as to what extent patterns of neural activity observed under such constraints actually manifest outside the laboratory in a manner that can be used to make an accurate inference about the latent state, associated cognitive process, or proximal behavior of the individual. Improving our understanding of when and how specific patterns of neural activity manifest in ecologically valid scenarios would provide validation for laboratory-based approaches that study similar neural phenomena in isolation and meaningful insight into the latent states that occur during complex tasks. We argue that domain generalization methods from the brain-computer interface community have the potential to address this challenge. We previously used such an approach to decode phasic neural responses associated with visual target discrimination. Here, we extend that work to more tonic phenomena such as internal latent states. We use data from two highly controlled laboratory paradigms to train two separate domain-generalized models. We apply the trained models to an ecologically valid paradigm in which participants performed multiple, concurrent driving-related tasks. Using the pretrained models, we derive estimates of the underlying latent state and associated patterns of neural activity. Importantly, as the patterns of neural activity change along the axis defined by the original training data, we find changes in behavior and task performance consistent with the observations from the original, laboratory paradigms. We argue that these results lend ecological validity to those experimental designs and provide a methodology for understanding the relationship between observed neural activity and behavior during complex tasks

Behavioural and neurophysiological differences in working memory function of depressed patients and healthy controls

Objective: Major depressive disorder (MDD) is associated with deficits in working memory. Several cognitive subprocesses interact to produce working memory, including attention, encoding, maintenenace and manipulation. We sought to clarify the contribution of functional deficits in these subprocesses in MDD by varying cognitive load during a working memory task. Methods: 41 depressed participants and 41 age- and gender-matched healthy controls performed the n-back working memory task at three levels of difficulty (0-, 1-, and 2-back) in a pregistered study. We assessed response times, accuracy, and event-related electroencephalography (EEG), including P2 and P3 amplitudes, and frontal theta power (4-8 Hz). Results: MDD participants had prolonged response times and more positive P3 amplitudes relative to controls. Working memory accuracy, P2 amplitudes and frontal theta event-related synchronisation did not differ between groups at any level of task difficulty. Conclusions: Depression is associated with generalized psychomotor slowing of working memory processes, as well as compensatory hyperactivity in frontal regions.Significance: These findings provide insights into MDD working memory deficits, indicating that depressed individuals dedicate greater levels of cortical processing and cognitive resources to achieve comparable workig memory performance to controls.</p

Mobile brain/body imaging (MoBI) of physical interaction with dynamically moving objects

© 2016 Jungnickel and Gramann. The non-invasive recording and analysis of human brain activity during active movements in natural working conditions is a central challenge in Neuroergonomics research. Existing brain imaging approaches do not allow for an investigation of brain dynamics during active behavior because their sensors cannot follow the movement of the signal source. However, movements that require the operator to react fast and to adapt to a dynamically changing environment occur frequently in working environments like assembly-line work, construction trade, health care, but also outside the working environment like in team sports. Overcoming the restrictions of existing imaging methods would allow for deeper insights into neurocognitive processes at workplaces that require physical interactions and thus could help to adapt work settings to the user. To investigate the brain dynamics accompanying rapid volatile movements we used a visual oddball paradigm where participants had to react to color changes either with a simple button press or by physically pointing towards a moving target. Using a mobile brain/body imaging approach (MoBI) including independent component analysis (ICA) with subsequent backprojection of cluster activity allowed for systematically describing the contribution of brain and non-brain sources to the sensor signal. The results demonstrate that visual event-related potentials (ERPs) can be analyzed for simple button presses and physical pointing responses and that it is possible to quantify the contribution of brain processes, muscle activity and eye movements to the signal recorded at the sensor level even for fast volatile arm movements with strong jerks. Using MoBI in naturalistic working environments can thus help to analyze brain dynamics in natural working conditions and help improving unhealthy or inefficient work settings

Psychologie und Gehirn 2007

Die Fachtagung "Psychologie und Gehirn" ist eine traditionelle Tagung aus dem Bereich psychophysiologischer Grundlagenforschung. 2007 fand diese Veranstaltung, die 33. Jahrestagung der „Deutschen Gesellschaft für Psychophysiologie und ihre Anwendungen (DGPA)“, in Dortmund unter der Schirmherrschaft des Instituts für Arbeitsphysiologie (IfADo) statt. Neben der Grundlagenforschung ist auch die Umsetzung in die Anwendung erklärtes Ziel der DGPA und dieser Tradition folgend wurden Beiträge aus vielen Bereichen moderner Neurowissenschaft (Elektrophysiologie, bildgebende Verfahren, Peripherphysiologie, Neuroendokrinologie, Verhaltensgenetik, u.a.) präsentiert und liegen hier in Kurzform vor

Behavioural and neurophysiological differences in working memory function of depressed patients and healthy controls

OBJECTIVE: Major depressive disorder (MDD) is associated with deficits in working memory. Several cognitive subprocesses interact to produce working memory, including attention, encoding, maintenance and manipulation. We sought to clarify the contribution of functional deficits in these subprocesses in MDD by varying cognitive load during a working memory task. METHODS: 41 depressed participants and 41 age and gender-matched healthy controls performed the n-back working memory task at three levels of difficulty (0-, 1-, and 2-back) in a pregistered study. We assessed response times, accuracy, and event-related electroencephalography (EEG), including P2 and P3 amplitudes, and frontal theta power (4-8 Hz). RESULTS: MDD participants had prolonged response times and more positive frontal P3 amplitudes (i.e., Fz) relative to controls, mainly in the most difficult 2-back condition. Working memory accuracy, P2 amplitudes and frontal theta event-related synchronisation did not differ between groups at any level of task difficulty. CONCLUSIONS: Depression is associated with generalized psychomotor slowing of working memory processes, and may involve compensatory hyperactivity in frontal and parietal regions. SIGNIFICANCE: These findings provide insights into MDD working memory deficits, indicating that depressed individuals dedicate greater levels of cortical processing and cognitive resources to achieve comparable working memory performance to controls