Cortical activation patterns of electrical pain stimulation using fNIRS

Until recently, pain assessment has largely relied on subjective self-reports such as questionnaires or VAS. This paper attempts to objectively quantify pain from a neurological point of view through the characteristics of cerebral hemodynamics. Functional near-infrared spectroscopy (fNIRS) measures cortical blood flow changes during electrical pain stimulation. The selected feature of pain measure is the concentration change of oxygenated hemoglobin. Cortical activation patterns and time-series analysis for region of interest shows that premotor cortex and primary motor cortex as well as somatosensory cortex are involved in pain perception. These results are consistent with the findings of fMRI studies on physical pain. Oxygenated hemoglobin is therefore likely to be a quantitative biomarker of pain.