Understanding inverse oxygenation responses during motor imagery: a functional nearinfrared spectroscopy study

HOLPER L.; D.E. SHALOM; WOLF M.; M SIGMAN

EUROPEAN JOURNAL OF NEUROSCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Año: 2011 vol. 33 p. 2318 - 2328

0953-816X

Motor imagery (MI) is described as the mental rehearsal of the voluntary movements. We recorded wireless functional near-infrared spectroscopy (fNIRS) over secondary motor areas during performance of MI and motor execution (ME) in 11 healthy subjects, who either executed or imagined two drawing tasks differing in shape and frequency, i.e. simple (circle, 0.2 Hz) and complex (curved shape, 0.333 Hz).At the group-level, results showed that fNIRS is capable of discriminating between the task-mode, i.e. MI versus ME, and the task-complexity, i.e. simple versus complex tasks. At the single-subject-level, the interesting finding was the observation of inverse oxygenation responses, i.e. decrease in ∆[O2Hb] and/or increase in ∆[HHb]. These inverse responses only occurred during MI tasks and were highly correlated in the first place, with the task-mode and second, the task-complexity. In this article we described our results indicating that inverse ∆[O2Hb] responses are likely to reflect individual differences in performance-related signals and may contribute as possible sources to the commonly observed inter-subject variability in fNIRS measurements. As MI is now widely used as a mental task in neurorehabilitative applications, the resulting oxygenation pattern may be of use for future developments. For this program to be successful it is crucial to determine the sources of inter-subject variability. Our study presents a first effort in this direction, indicating that MI related inverse ∆[O2Hb] responses are correlated in the first place, with the task-mode and second, with the task-complexity.