Cooperative particle filtering for tracking ERP subcomponents from multichannel EEG

In this study, we propose a novel method to investigate P300 variability over different trials. The method incorporates spatial correlation between EEG channels to form a cooperative coupled particle filtering method that tracks the P300 subcomponents, P3a and P3b, over trials. Using state space systems, the amplitude, latency, and width of each subcomponent are modeled as the main underlying parameters. With four electrodes, two coupled Rao-Blackwellised particle filter pairs are used to recursively estimate the system state over trials. A number of physiological constraints are also imposed to avoid generating invalid particles in the estimation process. Motivated by the bilateral symmetry of ERPs over the brain, the channels further share their estimates with their neighbors and combine the received information to obtain a more accurate and robust solution. The proposed algorithm is capable of estimating the P300 subcomponents in single trials and outperforms its non-cooperative counterpart

ERP detection based on smoothness priors

Objective: Detection of event-related potentials (ERPs) in electroencephalography (EEG) is of great interest in the study of brain responses to various stimuli. This is challenging due to the low signal-to-noise ratio of these deflections. To address this problem, a new scheme to detect the ERPs based on smoothness priors is proposed. Methods: The problem is considered as a binary hypothesis test and solved using a smooth version of the generalized likelihood ratio test (SGLRT). First, we estimate the parameters of probability density functions from the training data under the Gaussian assumption. Then, these parameters are treated as known values and the unknown ERPs are estimated under the smoothness constraint. The performance of the proposed SGLRT is assessed for ERP detection in post-stimuli EEG recordings of two oddball settings. We compared our method with several powerful methods regarding ERP detection. Results: The presented method performs better than the competing algorithms and improves the classification accuracy. Conclusion: SGLRT can be employed as a powerful means for different ERP detection schemes. Significance: The proposed scheme is opening a new direction in ERP identification which provides better classification results compared to several popular ERP detection methods

Effects of Galvanic Vestibular Stimulation on EEG Correlates of Attention

Galvanic Vestibular Stimulation (GVS) is a non-invasive form of neural stimulation that involves applying weak, electric current over the mastoid processes. Brief periods of GVS have been shown to provide transient relief from symptoms of inattention in hemi-spatial neglect and extinction patients. In addition, GVS has been shown to have effects on spatial- and reward-based attention in healthy participants. Despite this growing body of evidence, the underlying mechanisms associated with GVS-induced changes remain largely unknown. Better understanding of the underlying mechanisms of GVS may help to generate more efficient brain stimulation protocols and to direct treatment to those most likely to respond. Recently, studies have demonstrated that EEG may be a useful tool in investigating underlying changes with GVS. The current thesis therefore measured electrophysiological correlates known to be associated with attention in response to GVS. Chapters 2 and 3 investigated the impact of GVS on two ERP components, the N2pc and the P3, both shown to be associated with mechanisms involved in tasks often impaired in neglect patients. In these two chapters, GVS was shown to impact the N2pc relative to a sham condition. This may indicate that GVS impacted target detection and suppression of irrelevant distractors. In contrast, GVS did not impact the amplitude of the P3 relative to a sham group. Selective modulation of the N2pc, but not the P3 despite the same conditions, suggests a specific mechanism underlying GVS behavioural effects. Based on literature demonstrating differing efficiency of GVS effects using different waveforms and stimulation intensities, Chapter 4 aimed to investigate maximally effective protocols of GVS on behavioural measures of accuracy and reaction time. This chapter also aimed to extend and resolve discrepancies in the behavioural findings of Chapters 2 and 3. Chapter 4, however, demonstrated no differences between the various conditions. This indicated that GVS does not impact behavioural measures of accuracy and reaction time in the change-detection paradigm used. It has been demonstrated behaviourally that GVS can induce lateral shifts of spatial attention. Furthermore, these shifts have been shown to be polarity specific. Chapter 5 investigated these effects using an electrophysiological measure of spatial distribution of attention, steady state visual evoked potentials (SSVEPs). In this chapter GVS was not found to have any effect on SSVEP amplitude either for left-anodal/right-cathodal or right-anodal/left-cathodal GVS. This may indicate that the previously demonstrated effects are task dependent, and/or that GVS does not influence covert attention. Overall, this work provides new insight into underlying electrophysiological mechanisms influenced by GVS. These findings are presented and discussed with relevance to the theoretical and practical implications

Challenges for engineering students working with authentic complex problems

Engineers are important participants in solving societal, environmental and technical problems. However, due to an increasing complexity in relation to these problems new interdisciplinary competences are needed in engineering. Instead of students working with monodisciplinary problems, a situation where students work with authentic complex problems in interdisciplinary teams together with a company may scaffold development of new competences. The question is: What are the challenges for students structuring the work on authentic interdisciplinary problems? This study explores a three-day event where 7 students from Aalborg University (AAU) from four different faculties and one student from University College North Denmark (UCN), (6th-10th semester), worked in two groups at a large Danish company, solving authentic complex problems. The event was structured as a Hackathon where the students for three days worked with problem identification, problem analysis and finalizing with a pitch competition presenting their findings. During the event the students had workshops to support the work and they had the opportunity to use employees from the company as facilitators. It was an extracurricular activity during the summer holiday season. The methodology used for data collection was qualitative both in terms of observations and participants’ reflection reports. The students were observed during the whole event. Findings from this part of a larger study indicated, that students experience inability to transfer and transform project competences from their previous disciplinary experiences to an interdisciplinary setting

Exploring the practical use of a collaborative robot for academic purposes

This article presents a set of experiences related to the setup and exploration of potential educational uses of a collaborative robot (cobot). The basic principles that have guided the work carried out have been three. First and foremost, study of all the functionalities offered by the robot and exploration of its potential academic uses both in subjects focused on industrial robotics and in subjects of related disciplines (automation, communications, computer vision). Second, achieve the total integration of the cobot at the laboratory, seeking not only independent uses of it but also seeking for applications (laboratory practices) in which the cobot interacts with some of the other devices already existing at the laboratory (other industrial robots and a flexible manufacturing system). Third, reuse of some available components and minimization of the number and associated cost of required new components. The experiences, carried out following a project-based learning methodology under the framework of bachelor and master subjects and thesis, have focused on the integration of mechanical, electronic and programming aspects in new design solutions (end effector, cooperative workspace, artificial vision system integration) and case studies (advanced task programming, cybersecure communication, remote access). These experiences have consolidated the students' acquisition of skills in the transition to professional life by having the close collaboration of the university faculty with the experts of the robotics company.Postprint (published version