Optimization of a Motor Imagery Paradigm for Self-modulation of Bilateral Premotor Interhemispheric Functional Connectivity in fMRI Neurofeedback

Neuromodulation of a single brain region in an fMRI Neurofeedback experiment is a widely used technique with reported training effects on neuroplasticity and in behavioral changes. Recently, experiments aiming for modulation of functional relationship between segregated brain areas have been tested for their feasibility to understand underlying connectivity-based processing brain mechanisms. We performed a series of pilot studies to optimize an experimental protocol for interhemispheric functional connectivity modulation between bilateral premotor areas in a fMRI Neurofeedback setup, using a motor imagery paradigm. We have found that a better differentiation of correlation coefficient distributions between conditions was achieved with an optimized strategy with a reference task that consisted of the imagination of hand movement with gradual variation in the frequency of the imagined movements. Results also show that distinction between bimanual and unimanual motor imagery is not ideal for correlation-based differentiation using this paradigm. With this proof-of-concept study we conclude the feasibility of this setup as well as hypothesize that in future acquisitions, the reference tasks for an up-regulation condition should be based on this adaptive strategy and down-regulation condition should be optimized to promote the absence of activation in premotor areas.