Mental individuation of imagined finger movements can be achieved using TMS-based neurofeedback

Abstract

Neurofeedback (NF) in combination with motor imagery (MI) can be used for training individuals to volitionally modulate sensorimotor activity without producing overt movements. However, until now, NF methods were of limited utility for mentally training specific hand and finger actions. Here we employed a novel transcranial magnetic stimulation (TMS) based protocol to probe and detect MI-induced motor activity patterns in the primary motor cortex (M1) with the aim to reinforce selective facilitation of single finger representations. We showed that TMS-NF training but not MI training with uninformative feedback enabled participants to selectively upregulate corticomotor excitability of one finger, while simultaneously downregulating excitability of other finger representations within the same hand. Successful finger individuation during MI was accompanied by strong desynchronisation of sensorimotor brain rhythms, particularly in the beta band, as measured by electroencephalography. Additionally, informative TMS-NF promoted more dissociable EEG activation patterns underlying single finger MI, when compared to MI of the control group where no such feedback was provided. Our findings suggest that selective TMS-NF is a new approach for acquiring the ability of finger individuation even if no overt movements are performed. This might offer new treatment modality for rehabilitation after stroke or spinal cord injury.

Self-regulating arousal via pupil-based biofeedback

“…A priori power analyses based on own pilot data of a single training session with 30 trials (unpublished data) aiming for a power level of 80% resulted in a necessary sample size of 31 participants. As we expected training effects of our multi-session approaches, we recruited 28 participants for the NF (24 ± 5 years, 16 females) and 28 participants for the control group (24 ± 5 years; 13 females) of Experiment 1A, exceeding the sample size of other NF studies [34,70,71]. Participants were randomly assigned to a pupil-NF group and a control group.…”