Unraveling the Motor Cortex for Individual Finger Tapping Movements: An fNIRS Study

Finger tapping is one of the most reliable and widely used tasks for evoking activity in the motor cortex area of the brain, both for the brain-computer interface (BCI) and for evaluating the progress of certain brain diseases. Keeping in view the importance of dominance of the right hand, the goal of this study is to understand the response of each finger tapping alongside proposing a suitable finger tapping task for both BCI and medical imaging. With this in mind, we recruited 24 healthy subjects. Functional near-infrared spectroscopy (fNIRS) was used for brain imaging while the subjects performed a series of finger tapping tasks using each of the five fingers individually. From average hemodynamic results, the middle finger tapping task showed a maximum amount of activation in the motor cortex, whereas the index finger tapping task had the minimum activation compared with the other four fingers. The little finger and ring finger tapping tasks gave the most significant and widespread activation, respectively, when compared through brain activation maps. The activation was clustered on a single region for the thumb tapping task, whereas a wider area showed a very strong activation for the little finger and ring finger tapping tasks. Conclusively, this study is a step toward standardizing finger tapping and its related motor area activations, demonstrating that little finger tapping can best suit the purpose of a finger tapping task for BCI and medical imaging applications.