Pain Intensity Processing Within the Human Brain: A Bilateral, Distributed Mechanism

Abstract

Functional imaging studies of human subjects have identified a diverse assortment of brain areas that are engaged in the processing of pain. Although many of these brain areas are highly interconnected and are engaged in multiple processing roles, each area has been typically considered in isolation. Accordingly, little attention has been given to the global functional organization of brain mechanisms mediating pain processing. In the present investigation, we have combined positron emission tomography with psychophysical assessment of graded painful stimuli to better characterize the multiregional organization of supraspinal pain processing mechanisms and to identify a brain mechanism subserving the processing of pain intensity. Multiple regression analysis revealed statistically reliable relationships between perceived pain intensity and activation of a functionally diverse group of brain regions, including those important in sensation, motor control, affect, and attention. Pain intensity-related activation occurred bilaterally in the cerebellum, putamen, thalamus, insula, anterior cingulate cortex, and secondary somatosensory cortex, contralaterally in the primary somatosensory cortex and supplementary motor area, and ipsilaterally in the ventral premotor area. These results confirm the existence of a highly distributed, bilateral supraspinal mechanism engaged in the processing of pain intensity. The conservation of pain intensity information across multiple, functionally distinct brain areas contrasts sharply with traditional views that sensory-discriminative processing of pain is confined within the somatosensory cortex and can account for the preservation of conscious awareness of pain intensity after extensive cerebral cortical lesions.

Pharmacological FMRI in the development of new analgesic compounds

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Cortical Neurophysiological Modification after Peripheral Neuronal Sensitization

“…It is also suggested that these domains have a close relationship with the pain sensation system, as studies on patients with pain have recorded activity in these sites. A shift in the activated ECDs sites to the premotor cortex and supplementary motor area (SMA) following induced hyperalgesia in this study also indicates a relationship between the premotor cortex and pain sensation 13,14) .…”

Brain activity associated with painfully hot stimuli applied to the upper limb: A meta‐analysis

“…In many respects, this approach is well founded although some reservations persist about the degree to which activations reflect functions that are common across both innocuous and noxious sensory processing. A significant increase in signal from a brain region during painful stimulation does not preclude the possibility that the region is involved in processes common to both pain and other sensory experiences, albeit in an intensity-dependent manner [Coghill et al, 1999]. Consequently, when considering the results of the ALE analysis, it is important to acknowledge that painrelated activity in this context does not translate to a network that is dedicated exclusively to pain perception per se.…”