Abstract
Neurofeedback is a promising tool for brain rehabilitation and peak performance training. Neurofeedback approaches usually rely on a single brain imaging modality such as EEG or fMRI. Combining these modalities for neurofeedback training could allow to provide richer information to the subject and could thus enable him/her to achieve faster and more specific self-regulation. Yet unimodal and multimodal neurofeedback have never been compared before. In the present work, we introduce a simultaneous EEG-fMRI experimental protocol in which participants performed a motor-imagery task in unimodal and bimodal NF conditions. With this protocol we were able to compare for the first time the effects of unimodal EEG-neurofeedback and fMRI-neurofeedback versus bimodal EEG-fMRI-neurofeedback by looking both at EEG and fMRI activations. We also propose a new feedback metaphor for bimodal EEG-fMRI-neurofeedback that integrates both EEG and fMRI signal in a single bi-dimensional feedback (a ball moving in 2D). Such a feedback is intended to relieve the cognitive load of the subject by presenting the bimodal neurofeedback task as a single regulation task instead of two. Additionally, this integrated feedback metaphor gives flexibility on defining a bimodal neurofeedback target. Participants were able to regulate activity in their motor regions in all NF conditions. Moreover, motor activations as revealed by offline fMRI analysis were stronger during EEG-fMRI-neurofeedback than during EEG-neurofeedback. This result suggests that EEG-fMRI-neurofeedback could be more specific or more engaging than EEG-neurofeedback. Our results also suggest that during EEG-fMRI-neurofeedback, participants tended to regulate more the modality that was harder to control. Taken together our results shed first light on the specific mechanisms of bimodal EEG-fMRI-neurofeedback and on its added-value as compared to unimodal EEG-neurofeedback and fMRI-neurofeedback.
Highlights
Neurofeedback (NF) is a technique that consists in feeding back information to an individual about his/her brain activity in real-time in order for him/her to learn to better control an aspect of it (Hammond, 2011; Birbaumer et al, 2013)
We introduce an motor imagery (MI)-based EEG-fMRI-NF protocol and compare its effects with EEG-NF and fMRI-NF by looking at the MI-related EEG and fMRI activity patterns elicited in each NF condition
Though continuous MI is thought to induce a succession of event-related desynchronization (ERD) it can be hard to observe a continuous desynchronization throughout the duration of the continuous MI (Jeon et al, 2011; Rimbert et al, 2015) This highlights the difficulty of designing the task for bimodal EEG-fMRI-NF given the different spatiotemporal dynamics of EEG and fMRI
Summary
Neurofeedback (NF) is a technique that consists in feeding back information to an individual about his/her brain activity in real-time in order for him/her to learn to better control an aspect of it (Hammond, 2011; Birbaumer et al, 2013). In the context of NF, combining EEG and fMRI enables to return to a subject two signals at the same time, one that contains temporally fine information about brain oscillations and one that contains spatially fine information about specific brain regions. The simultaneous combination of EEG-NF and fMRI-NF was introduced for the first time by Zotev et al (2014) who made a proof-of-concept application of this new type of NF in the training of emotional self-regulation. In their pioneering work, the authors hypothesized that bimodal EEG-fMRI-NF could be more efficient than EEG-NF or fMRI-NF performed alone. To our knowledge, this hypothesis has not been studied so far
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