Spatio-temporal differences in brain oxygenation between movement execution and imagery: a multichannel near-infrared spectroscopy study.

Near-infrared spectroscopy (NIRS) was used to assess human motor-cortex oxygenation changes in response to self-paced movements as well as movement imagery. We used a 24 channel NIRS-system which allows non-invasive monitoring of cerebral oxygenation changes in the human brain induced by cortical activity. From previous studies it is known that motor imagery activates sensorimotor areas similar to those activated during execution of the same movement. Sixteen healthy subjects were recruited and the changes in concentration of oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) were examined during a simple right and left hand tapping task and during kinesthetic movement imagery. All subjects showed significant increases in oxy-Hb during both tasks compared to the resting period, but with different onset latencies of oxygenation. During left and right movement imagery, the oxy-Hb concentration increased about 2 s later compared to real movement execution. Furthermore, the oxygenation found was bilaterally represented for both tasks but with temporal differences. The present study reported new results concerning timing and topographical distribution of the hemodynamic response during motor imagery measured by near-infrared spectroscopy.

Near-infrared spectroscopy based neurofeedback training increases specific motor imagery related cortical activation compared to sham feedback.

In the present study we implemented a real-time feedback system based on multichannel near-infrared spectroscopy (NIRS). Prior studies indicated that NIRS-based neurofeedback can enhance motor imagery related cortical activation. To specify these prior results and to confirm the efficacy of NIRS-based neurofeedback, we examined changes in blood oxygenation level collected in eight training sessions. One group got real feedback about their own brain activity (N=9) and one group saw a playback of another person's feedback recording (N=8). All participants performed motor imagery of a right hand movement. Real neurofeedback induced specific and focused brain activation over left motor areas. This focal brain activation became even more specific over the eight training sessions. In contrast, sham feedback led to diffuse brain activation patterns over the whole cortex. These findings can be useful when training patients with focal brain lesions to increase activity of specific brain areas for rehabilitation purpose.