Relationship between intensity of toe motion and cerebral activation: A near-infrared spectroscopy study

[Purpose] We investigated the relationship between the intensity of toe motion and Δ[Oxy-Hb] in motor cortical areas. [Subjects] Twelve healthy adults (7 females and 5 males: 26.9±5.3 years of age) participated in the study. [Methods] The motor tasks were isometric and isotonic right toe flexion. The participants performed the tasks under two conditions: maximum and moderate effort. We measured the motor cortical activity using NIRS, and the extent and amplitude of the activations were compared between the two conditions for each task. [Results] In the isotonic flexion task, the extent of the activation area and the amplitude of Δ[Oxy-Hb] were dependent on the movement intensity. On the other hand, there was no significant difference between the two conditions in the isometric flexion task. [Conclusion] We clarified that cerebral activation is influenced by the task motion and the participant's effort.