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.