Chapter 18 Cortical processing of noxious information in humans: a magnetoencephalographic study

Publisher Summary This chapter evaluates the timing of multiple cortical activities following noxious stimulation using magnetoencephalography (MEG). MEG has an advantage over imaging modalities as it can provide temporal information about an activity in addition to its location. The somatosensory evoked magnetic fields (SEFs) were measured using dual 37-channel axial-type first-order biomagnetometers. An early SI activity shows shorter response latency than other source activities. The results reveal that onset latencies of MT and the cingulate cortex corresponded to the peak latencies of insular activity; hence, it is possible that both MT and the cingulate cortex were driven by the insula. It also suggests two parallel pathways of pain processing: (1) through the lateral thalamic nuclei (SI and SII), serially and (2) through the medial thalamic nuclei, insula, and limbic structures, serially. These two distinct pathways seem to correspond to the classic dichotomy of pain processing, the lateral and medial systems, which are involved in discriminative and emotional aspects of pain, respectively.