Functional Neuroimaging of Pain Using EEG and fMRI

Functional imaging of brain networks associated with pain processing is of vital importance to aid developing new pain-relief therapy and to better understand the mechanisms of brain function. The pain response in the brain is a complex process, which involves multiple cortical brain regions, such as primary and secondary somatosensory cortices, anterior cingulate cortex, and insular cortex . Recent advancement in neuroimaging techniques suggests the possibility to map the brain structure and networks that involve pain processing. Electroencephalography (EEG) is a noninvasive monitoring technique, which is widely used to probe neurological disorders with high temporal resolution. Few attempts have been made to use EEG to map the active brain regions in pain patients. Functional MRI (fMRI) measures the hemodynamic brain response and could image the active brain regions with high spatial resolution. Studies have shown that fMRI is a useful tool to delineate the brain regions associated with pain processing. Recent studies from simultaneous EEG and fMRI recording have suggested that the EEG response to the pain may be correlated with the fMRI response, and both EEG and fMRI could be used to image the brain pain processing regions, such as the primary somatosensory cortex and anterior cingulate cortex. The aim of this research is to develop and evaluate a functional neuroimaging approach using EEG, fMRI and EEG-fMRI, in pain study. EEG, fMRI, or simultaneous EEG-fMRI will be collected in healthy subjects who receive external thermal stimulation inducing pain. The painful stimuli will be delivered at different intensity levels and the subject pain rating will be collected. The imaging technique combines the EEG signal with high temporal resolution and the fMRI signal with high spatial resolution to obtain a spatiotemporal imaging of the brain electrophysiological and hemodynamic activity in response to different levels of pain. Cross validation between this method and subject pain score will be used to quantitatively and qualitatively evaluate the technique. The successful completion of the current protocol will help establish an important imaging technology accessing pain level in an objective way.