Source-based neurofeedback methods using EEG recordings: training altered brain activity in a functional brain source derived from blind source separation

A developing literature explores the use of neurofeedback in the treatment of a range of clinical conditions, particularly ADHD and epilepsy, whilst neurofeedback also provides an experimental tool for studying the functional significance of endogenous brain activity. A critical component of any neurofeedback method is the underlying physiological signal which forms the basis for the feedback. While the past decade has seen the emergence of fMRI-based protocols training spatially confined BOLD activity, traditional neurofeedback has utilized a small number of electrode sites on the scalp. As scalp EEG at a given electrode site reflects a linear mixture of activity from multiple brain sources and artifacts, efforts to successfully acquire some level of control over the signal may be confounded by these extraneous sources. Further, in the event of successful training, these traditional neurofeedback methods are likely influencing multiple brain regions and processes. The present work describes the use of source-based signal processing methods in EEG neurofeedback. The feasibility and potential utility of such methods were explored in an experiment training increased theta oscillatory activity in a source derived from Blind Source Separation of EEG data obtained during completion of a complex cognitive task (spatial navigation). Learned increases in theta activity were observed in two of the four participants to complete 20 sessions of neurofeedback targeting this individually defined functional brain source. Source-based EEG neurofeedback methods using Blind Source Separation may offer important advantages over traditional neurofeedback, by targeting the desired physiological signal in a more functionally and spatially specific manner. Having provided preliminary evidence of the feasibility of these methods, future work may study a range of clinically and experimentally relevant brain processes targeting individual brain sources by source-based EEG neurofeedback

Control freaks: Towards optimal selection of control conditions for fMRI neurofeedback studies

fMRI Neurofeedback research employs many different control conditions. Currently, there is no consensus as to which control condition is best, and the answer depends on what aspects of the neurofeedback-training design one is trying to control for. These aspects can range from determining whether participants can learn to control brain activity via neurofeedback to determining whether there are clinically significant effects of the neurofeedback intervention. Lack of consensus over criteria for control conditions has hampered the design and interpretation of studies employing neurofeedback protocols. This paper presents an overview of the most commonly employed control conditions currently used in neurofeedback studies and discusses their advantages and disadvantages. Control conditions covered include no control, treatment-as-usual, bidirectional-regulation control, feedback of an alternative brain signal, sham feedback, and mental-rehearsal control. We conclude that the selection of the control condition(s) should be determined by the specific research goal of the study and best procedures that effectively control for relevant confounding factor

Learning to regulate homeostatic brain networks

Eine dynamische Balance der physiologischen Gegebenheiten wie Körpertemperatur, Blutdruck, Blut-PH-Wert, Hormonspiegel, Blutzucker und Insulinkonzentration ist für die Gesundheit und das Überleben unverzichtbar. Viele Krankheiten haben eine Störung der Homöostase zur Folge. Vor allem das Nerven- und das Hormonsystem steuern Regulationsmechanismen und sobald diese ein Ungleichgewicht feststellen, gibt es passende biochemische oder physiologische Feedback-Kreisläufe, die den Gesamtzustand in die Balance zurückführen. Diese Dissertation untersucht neuartige Methoden des Echtzeit-Neurofeedbacks, das auf funktioneller Magnetre-sonanztomographie basiert (Real-time functional magnetic resonance imaging – rt-fMRI-NF), um es gesunden Probanden und Patienten zu ermöglichen, homöostatische Netzwerke des Gehirns zu regulieren. Die erste Studie hatte zum Ziel, die Auswirkungen der Hochregulierung der funktionellen Konnektivität durch rt-fMRI-NF-Training (engl. Functional connectivity – FC) zwischen Beloh-nungs- und impulsivitätsregulierenden Gehirnarealen auf das Essverhalten zu untersuchen. Diese Studie war ein Pilotexperiment im Pre-Post-Schema. Die zweite Studie untersuchte die Möglichkeit, die funktionelle Konnektivität zwischen der anterioren Insula (AIC) und dem soma-tosensorischen Kortex (SC) durch Belohnung von gleichzeitiger Aktivität dieser Regionen zu be-einflussen. AIC und SC sind Gehirnregionen, die physiologische Zustandsinformationen von Kör-pergewebe und großflächigen Hautsegmenten erhalten. Wir nahmen an, dass die funktionelle Verbindung zwischen diesen Regionen die Verarbeitung dieser Signale der inneren Organe und Körpergewebe übernimmt. Dies stellt einen Kernbereich des Gefühlskonzeptes von James-Lang dar. In der dritten Studie untersuchten wir, ob Patienten mit kontaminationsbezogenen Zwangsgedanken und Waschzwang lernen können, ihre BOLD-Aktivität in der Insula herunterzu-regulieren, wenn sie mit ekelerregenden oder Angst hervorrufenden Stimuli konfrontiert wer-den. Die Ergebnisse der ersten Studie zeigten, dass die willentliche Hochregulierung der Korrela-tion zu einer erhöhten funktionellen Konnektivität zwischen dem dorsolateralen präfrontalen Kortex (dlPFC) und dem ventromedialen präfrontalen Kortex (vmPFC) führt. Diese Konnektivität betrifft Selbstkontrolle und die Entscheidung für gesunde Nahrungsmittel. Die Verhaltenstests deuten darauf hin, dass die Probanden sich in der Transfersitzung (nach der Intervention) für weniger ungesunde Nahrungsmittel entscheiden als in der Sitzung vor der Intervention. Die zweite Studie bestätigte unsere Hypothese, dass die willentliche Hochregulierung von gleichzei-tiger BOLD-Aktivität von AIC und SC deren funktionale Konnektivität erhöht. Diese Verbindung ermöglicht eine verstärkte Körperwahrnehmung und ein verändertes subjektives Gefühlserle-ben. Wir beobachteten, dass die Veränderung der funktionellen Konnektivität zwischen AIC und SC die Leistung der Probanden in der Aufgabe (Wahrnehmung des Herzschlags) verbesserte. In der dritten Studie fanden wir heraus, dass Patienten mit Zwangsstörungen (OCD) nach einigen Trainingseinheiten die Selbstkontrolle der BOLD-Aktivität der Insula erreichen konnten. Fasst man die Ergebnisse der drei Studien zusammen, konnten wir zeigen, dass die Fähigkeit des Ge-hirns zur homöostatischen Selbstregulierung durch die Verwendung von rt-FMRI-Training ver-bessert werden kann. Zudem ist nun klarer, dass die Veränderung und die Modulation von neu-ronalen Pfaden in Gehirnnetzwerken, die der Selbstkontrolle, der Entscheidungsfindung und der Gefühlswahrnehmung zugrunde liegen, zu vielversprechenden Verhaltensveränderungen führt

Targeted reinforcement of neural oscillatory activity with real-time neuroimaging feedback

AbstractBiofeedback and brain-computer interfacing using EEG has been receiving continuous and increasing interest. However, the limited spatial resolution of low-density scalp recordings is a roadblock to the unequivocal monitoring and targeting of neuroanatomical regions and physiological signaling. This latter aspect is pivotal to the actual efficiency of neurofeedback procedures, which are expected to engage the modulation of well-identified components of neural activity within and between predetermined brain regions. Our group has previously contributed to demonstrate the principles of real-time magnetoencephalography (MEG) source imaging. Here we show how the technique was further developed to provide healthy subjects with region-specific neurofeedback to modulate successfully predetermined components of their brain activity in targeted brain regions. Overall, our results positively indicate that neurofeedback based on time-resolved MEG imaging has the potential to become an innovative therapeutic approach in neurology and neuropsychiatry

Physiological regulation of chronic tinnitus: A new methodological approach

Decrease of auditory alpha-rhythm might lead to tinnitus which it calls a rehabilitation strategy using training to increase auditory alpha in chronic tinnitus patients. A novel auditory alpha monitoring method was devised to circumvent the inverse problem of standard EEG source localization methods. To prevent projection of alpha from somatosensory and occipital cortex, alpha-blockade of these two regions using tactile and visual stimulations is integrated in an EEG neurofeedback set-up. The monitoring online source method’s results showed rigorous tracking of auditory alpha activity purely from the sensor-level while the up-regulation of auditory alpha activity was very difficult for tinnitus patients. Therefore, only contingent feedback was applied instead of using a control condition or control group. Although the neurofeedback training exerted a positive effect on the tinnitus symptoms, this effect was not a consequence of neurophysiological changes, but it was probably the effect of positive expectancy and the reduction of cognitive dissonance related to the attribution of concentration and effort. Different reasons could be responsible for this lack of covariation between neurophysiology and behavior like short training time for up-regulation of alpha activity or permanent neuronal reorganization. However, the developed on-line neurofeedback of localized alpha allows systematic replication and variation of the determining variables of neurofeedback training in tinnitus in future larger clinical trials

Time-varying functional connectivity and dynamic neurofeedback with MEG: methods and applications to visual perception

Cognitive function involves the interplay of functionally-separate regions of the human brain. Of critical importance to neuroscience research is to accurately measure the activity and communication between these regions. The MEG imaging modality is well-suited to capturing functional cortical communication due to its high temporal resolution, on the millisecond scale. However, localizing the sources of cortical activity from the sensor measurements is an ill-posed problem, where different solutions trade-off between spatial accuracy, correcting for linear mixing of cortical signals, and computation time. Linear mixing, in particular, affects the reliability of many connectivity measures. We present a MATLAB-based pipeline that we developed to correct for linear mixing and compute time-varying connectivity (phase synchrony, Granger Causality) between cortically-defined regions interfacing with established toolboxes for MEG data processing (Minimum Norm Estimation Toolbox, Brainstorm, Fieldtrip). In Chapter 1, we present a new method for localizing cortical activation while controlling cross-talk on the cortex. In Chapter 2, we apply a nonparametric statistical test for measuring phase locking in the presence of cross-talk. Chapters 3 and 4 describe the application of the pipeline to MEG data collected from subjects performing a visual object motion detection task. Chapter 5 focuses on real-time MEG (rt-MEG) neurofeedback which is the real-time measurement of brain activity and its self-regulation through feedback. Typically neurofeedback modulates directly brain activation for the purpose of training sensory, motor, emotional or cognitive functions. Direct measures, however, are not suited to training dynamic measures of brain activity, such as the speed of switching between tasks, for example. We developed a novel rt-MEG neurofeedback method called state-based neurofeedback, where brain activity states related to subject behavior are decoded in real-time from the MEG sensor measurements. The timing related to maintaining or transitioning between decoded states is then presented as feedback to the subject. In a group of healthy subjects we applied the state-based neurofeedback method for training the time required for switching spatial attention from one side of the visual field to the other (e.g. left side to right side) following a brief presentation of a visual cue. In Chapter 6, we used our pipeline to investigate training-related changes in cortical activation and network connectivity in each subject. Our results suggested that the rt-MEG neurofeedback training resulted in strengthened beta-band connectivity prior to the switch of spatial attention, and strengthened gamma-band connectivity during the switch. There were two goals of this dissertation: First was the development of the MATLAB-based pipeline for computing time-evolving functional connectivity analysis in MEG and its application to visual motion perception. The second goal was the development of a real-time MEG neurofeedback method to train the dynamics of brain states and its application to a group of healthy subjects.2019-11-02T00:00:00

Motivational underpinnings of negative affect as revealed by emotional modulation of EEG bands

The studies reported in this thesis pertain to a project aiming at investigating the motivational underpinnings of psychopathologies characterized by negative affect, such as anxiety and depression. Unbalanced or conflicting motivational tendencies can lead to disturbances in emotional responding and ongoing affect, which are often associated with psychopathology. As it will be introduced in the first chapter, motivational drives are thought to be sustained by two main systems in the brain, namely the appetitive and the defensive motivational circuits. The appetitive system contributes to approach behaviors in response to rewarding and pleasant stimuli. On the other side, the defensive system drives withdrawal from threat and is important for triggering unpleasant emotions. Therefore, emotions can be described as action dispositions reflecting basic tendencies to both approach and withdrawal in response to emotional stimuli. Several models postulated that negative affect in psychopathology arises from an excessive activation of the defensive system, which leads to an increased and dominant tendency to actively withdrawal from potential threats in the environment. Partially contrasting with this theoretical conceptualization, the aim of this thesis was to investigate whether negative affect could also manifest in psychopathologies which are not characterized by a straightforward increase in withdrawal tendencies. In this sense, EEG correlates of motivational tendencies in response to emotional stimuli were investigated in blood phobia and in dysphoria (i.e., subclinical depression). Accordingly, blood phobia, contrary to other specific phobias, is not associated with an increase in action disposition in response to the feared stimulus. Therefore, negative affect in these individuals does not seem to arise from a pronounced tendency to actively withdrawal. Depression represents another example of condition in which it is not clear whether negative affect is subtended by a dominance of the withdrawal system or by a lack in appetitive motivation. Accordingly, it is matter of debate whether depressed mood is due to preferential processing of unpleasant stimuli or reduced sensitivity to rewards and positive emotions. In order to investigate these aspects, three studies were conducted. In study 1, it was chosen to investigate modulation of EEG bands during an emotional Go/Nogo task in blood phobia. The emotional Go/Nogo task, including phobia-related pictures, along with phobia-unrelated unpleasant, neutral and pleasant stimuli, was ideal to investigate the lack of action disposition in blood phobia. Results showed that individuals with blood phobia display a conflicting motivational pattern, characterized by co-occurring tendencies to attend and avoid the feared stimulus, in strong contrast with other phobias. In Studies 2 and 3, modulation of EEG bands during an emotional imagery task in individuals with dysphoria was investigated. The emotional imagery is an active task, in which individuals are requested to actively imagine emotional scenarios; therefore it was well suited to investigate emotional modulation of appetitive and defensive motivational tendencies. Overall, results supported the idea that depressed mood in dysphoria is due to a lack in appetitive motivation, accompanied by a reduction in processing of pleasant stimuli. Again, we found no evidences of increased defensive motivation and tendency to withdrawal in dysphoric individuals. Finally, our research focused on possible clinical implications of the abovementioned findings, concerning the application of bio-behavioral trainings for the reduction of negative affect. In line with the pertaining literature, results from of our first three studies showed that frontal alpha asymmetry is an informative index of motivational tendencies underlying affect and emotional responses. Therefore, a fourth study was conducted, aimed at evaluating the effectiveness of a frontal alpha asymmetry neurofeedback training in reducing negative affect, anxiety and depressive symptoms in healthy individuals. After five training sessions, healthy individuals succeeded in reducing right compared to left prefrontal activity, through a specific increase in right frontal alpha. In accordance with the role of the right prefrontal cortex in defensive motivation and negative affect, this increase in right frontal alpha power was associated with a significant reduction in negative affect and anxiety. In conclusion, the present thesis confirms and extends the link between motivational tendencies and negative affect, showing that negative affect is not exclusively associated with an increase in defensive motivation and in active withdrawal disposition. Accordingly, among psychopathologies characterized by negative affect, blood phobia and dysphoria do not display the typically predicted motivational pattern. A first step toward the transition from basic research to clinical application has been proposed, with the implementation of an EEG-based neurofeedback for the reduction of negative affect. Overall, the present work is of potential relevance for a better understanding of the motivational underpinnings of psychopathologies characterized by negative affect, also providing a strong rationale for the application of bio-behavioral trainings