Neural correlates of motor imagery neurofeedback training

Author(s)

Carlos Alberto Stefano Filho

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin
• Defense date: 2021-10-27

Examining board members

Gabriela Castellano; Rickson Coelho Mesquita; Diogo Coutinho Soriano; Alexandre Hideki Okano; Sarah Negreiros de Carvalho Leite

• Advisor: Romis Ribeiro de Faissol Attux; Gabriela Castellano

Abstract

Neurofeedback (NFB) training aims to enable its user to develop strategies for modulating his/her brain activity in real time. The technique can be applied to motor rehabilitation protocols by appropriately identifying mental patterns evoked by motor imagery (MI), a task that requires the conscious planning of a motor action, but without overt motor execution. Such patterns can be used to provide feedback (usually through visual stimuli) to the system’s user, allowing them to monitor the adequacy of their strategy to the performance of MI in real time. Therefore, this type of approach can promote greater engagement of the central nervous system in rehabilitation protocols, thus yielding additional benefits to more traditional protocols. Regardless of a promising scenario, several issues still remain, such as: isolating, from external factors, the intrinsic contribution of NFB to observed improvements; and identifying the neural correlates of NFB training that could justify such improvements. In this thesis, we developed a NFB system for MI capability improvement to investigate these matters. Thirty subjects without history of diagnosable neurological conditions participated in this study. They underwent 10 MI practice sessions and were divided equally into three groups: control, receiving no feedback at all; sham, receiving a "false" feedback; and active, whose participants received actual NFB from power modulation features of electroencephalography signals. An experiment with five children with cerebral palsy (CP) was also carried out. Our results indicate more pronounced improvements in MI response evocation frequency and in the distinguishability of the MI tasks for the active group, whereas little-to-no change was found for the control group. Additionally, merely the existence of visual stimulation perceived as feedback by the sham participants was enough to disrupt results for this group, resulting in almost random outcomes, indicating a possible placebo effect for NFB practice. Moreover, we have also verified changes in functional connectivity patterns for the active group and for the CP children during MI: such patterns became more subject-specific following the NFB intervention. A similar result was found for the CP patients. We argue that an individualized NFB protocol, even with a simple graphic interface, seems to constitute an effective tool for favoring functional brain changes, both from the functional connectivity perspective, and from the comparison of neuroelectrophysiological markers. Altogether, our findings can aid future studies in better identifying neural alterations that are intrinsic, or extrinsic, to the process of feedback, thus aiding in better defining NFBT guidelines and best practices for motor rehabilitation methodologies (AU)

• FAPESP's process: 16/22116-9 - Investigation of the neurofeedback technique using MRI
• Grantee: Carlos Alberto Stefano Filho
• Support Opportunities: Scholarships in Brazil - Doctorate