Real-time fMRI neurofeedback in stroke rehabilitation: A systematic review

Background: The last two decades have witnessed a proliferation of rehabilitation strategies to promote functional recovery of motor and cognitive deficits after stroke. None, however, have shown satisfactory results, most likely because they mainly focus on damage and reorganization of local circuitry without considering brain-wide effects. In the present review, we argue that real-time functional magnetic resonance imaging (rt-fMRI) neurofeedback may be effective for reducing stroke-induced behavioural deficits, being a closed-loop approach based on individual brain dynamics. This technique has been applied to treat neurodevelopmental and neuropsychiatric disorders, but its effectiveness in the field of stroke rehabilitation has not been examined yet. We systematically review the effectiveness and quality of existing rt-fMRI neurofeedback studies aimed at modulating behaviour, and sketch out current limitations and future directions for stroke rehabilitation. Results: Based on predefined search criteria, we selected and examined 33 rt-fMRI neurofeedback studies, including 651 healthy individuals and 15 stroke patients in total. We found a learned modulation of brain activity, with associated changes at the neural level, or both the neural and the behavioural level, in 16 of the 19 motor function studies, and 11 of the 14 cognitive function studies. Importantly, three studies including 15 stroke survivors provided indications that modulation of brain activity through rt-fMRI neurofeedback can lead to a behavioural improvement in motor or cognitive function. Discussion and implications: The findings of this systematic review hint toward the possible use of rt-fMRI neurofeedback for ameliorating motor and cognitive deficits in stroke survivors. Nonetheless, the limited number of patient studies does not allow to draw conclusions about the efficacy and effectiveness of this technique in clinical settings. We suggest future randomized experiments to include a relatively large number of stroke patients and systematic outcome measures on behavioural function. This will permit group-level inferences about the efficacy of rt-fMRI neurofeedback. We also suggest to perform an assessment of both short- and long-term effects of rf-fMRI neurofeedback to shed light on the degree with which neurofeedback can trigger sustained changes in brain activity and, consequently, behaviour.status: publishe