Differential neural plasticity of individual fingers revealed by fMRI neurofeedback

Previous work has shown that fMRI activity patterns associated with individual fingers can be shifted by temporary impairment of the hand (e.g. by gluing two fingers together for 24 hours). Here, we investigated whether these neural activity patterns could be modulated endogenously and whether any behavioral changes result from modulation of these patterns. We used decoded neurofeedback in healthy individuals to encourage participants to shift the neural activity pattern in sensorimotor cortex of the middle finger towards the index finger, and the ring finger towards the little finger. We first mapped out the neural activity patterns for all fingers of the right hand in an fMRI pattern localizer session. Then, in three subsequent neurofeedback sessions, participants were rewarded after middle/ring finger presses according to their activity pattern overlap during each trial. A force-sensitive keyboard was used to ensure that participants were not altering their physical finger coordination patterns. We found evidence that participants could learn to shift the activity pattern of the 4th digit (ring finger) but not of the 3rd digit (middle finger). Increased variability of these activity patterns during the localizer session was associated with the ability of participants to modulate them using neurofeedback. Participants also showed an increased preference for the ring finger but not for the middle finger in a post-neurofeedback motor task. Our results show that neural activity and behaviors associated with the ring finger are more readily modulated than those associated with the middle finger. These results have broader implications for rehabilitation of individual finger movements, which may be limited or enhanced by individual finger plasticity after neurological injury.