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

Abstract

Abstract:The capacity of pain to alert against potential injury or focus attention on damaged tissue is enhanced by the intrinsically aversive nature of the experience. Finding methods to relieve pain will ultimately be facilitated by deeper understanding of the processes that contribute to the experience, and functional brain imaging has contributed substantially toward that end. An impressive body of literature has identified a distributed network of pain-related activity in the brain that is subject to considerable modulation by different stimulus parameters, contextual factors, and clinical conditions. The fundamental substrates of the pain network are yet to be distilled from the highly variable results of studies published thus far. Qualitative reviews of the pain-imaging literature have been contributory, but lack the greater surety of quantitative methods. We employ the activation likelihood estimation (ALE) meta-analytic technique to establish the most consistent activations among studies reporting brain responses subsequent to the application of noxious heat. A network of pain-related activity was replicated for stimuli to either upper limb that included two discernible regions of the mid-anterior cingulate cortex, bilateral thalami, insula, and opercula cortices, posterior parietal cortex, premotor cortex, supplementary motor area, and cerebellum. The findings of the meta-analysis resonate with other streams of information that continue to enhance our understanding of pain in the brain. The results also point toward new areas of research that may be fruitful for the exploration of central pain processing. Hum Brain Mapp 25:129 -139, 2005.

Threatening a rubber hand that you feel is yours elicits a cortical anxiety response

“…We also found activation in the anterior insular cortex, and this too is known to be activated during anticipation of pain, experience of pain, and empathy for pain (15)(16)(17). Coactivation of the ACC and anterior insula in imaging experiments is strongly linked to emotional processing and introceptive awareness (28,35,36). The activity in these areas probably reflected anxiety because there was a correlation between the increase in anxiety in the ownership condition and the increase in the threat-evoked BOLD responses in the ACC and insular cortex in this condition (SI Fig.…”

“…Furthermore, activity in the SMA and pre-SMA increases before voluntary movement, reflecting the preparation to move (21)(22)(23)(24)(25). It is also commonly observed that medial wall motor areas are activated when humans experience or anticipate painful stimuli (16,(26)(27)(28). It has been suggested that this motor activity reflects the urge to remove the hand (27,29) or preparation to generate an escape motor response (26).…”

“…Nineteen right-handed, healthy participants took part in the imaging experiments (11 males; all aged [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Participation was limited to subjects who felt the rubber-hand illusion in preliminary testing; 9 other subjects were not scanned because they did not experience the illusion (see Prescanning Testing Phase in SI Text).…”

“…For statistical inference we then used the threshold of P Ͻ 0.05 after a correction for the number of multiple comparisons (FamilyWise-Error correction). Because we had an a priori hypothesis that threatening the hand would activate certain areas associated with pain anticipation and anxiety, we used a small volume correction in these regions (15,17,28,36) …”

Unique, common, and interacting cortical correlates of thirst and pain

“…Studies of thirst-related brain activity have identified a network including the hypothalamus, thalamus, insula, parahippocampus, somatosensory cortex, anterior cingulate, posterior cingulate, and cerebellum (1,(10)(11)(12). A metaanalysis of pain imaging studies revealed a consistent network incorporating activity in the diencephalon and posterior parietal, insula, and limbic cortices and cerebellum (13). Craig (2) and Vogt (14) have suggested that the insula and anterior cingulate are key loci in the conscious experiences arising from interoceptive inputs.…”