Spatial tuning in nociceptive processing is driven by attention

Abstract

When the source of nociception expands across a body area, the experience of pain increases due to the spatial integration of nociceptive information. This well-established effect is called spatial summation of pain (SSp) and has been the subject of multiple investigations. Here, we used cold-induced SSp to investigate the effect of attention on the spatial tuning of nociceptive processing. Forty pain-free volunteers (N=40, 20 females) participated in this experiment. They took part in an SSp paradigm based on three hand immersions into cold water: Participants either immersed the ulnar segment (a), radial segment (b) or both hand segments (a+b) and provided overall pain ratings. In some trials based on a+b immersions, they were also asked to provide divided (i.e., first pain in a then in b; or reversed) and directed attention ratings (i.e., pain only in a or b). Results confirmed a clear SSp effect in which reported pain during immersions of a or b was less intense than pain during immersions of a+b (p<0.001). Data also confirmed that spatial tuning was altered. SSp was fully abolished when participants provided two ratings in a divided fashion (p<0.001). Furthermore, pain was significantly lower when attention was directed only to one segment (a OR b) during a+b immersion (p<0.001). We conclude that spatial tuning is dynamically driven by attention as reflected in abolished SSp. Directed attention was sufficient to focus spatial tuning and abolish SSp. Results support the role of cognitive processes such as attention in spatial tuning.

Spatial summation of pain is associated with pain expectations: Results from a home-based paradigm

“…They provoked robust SSp and its disruption in the group of patients suffering from chronic pain. Two recent studies from our group confirmed the existence of SSp during hand immersion by dividing the hand into 5 segments [38], or two halves (ulnar and radial side) [1].…”

“…The authors compared pain provoked by the immersion of one finger to pain provoked by whole hand immersion and did not observe SSp. However, the study sample was small (n=2), and results could be explained by individual differences in SSp which are known to be large: lateral inhibition [34] may paradoxically lead to lower pain in larger stimulated area [1,34]. In a study by Westcott et al [46], SSp was confirmed in 40 individuals by demonstrating more intense pain during full-hand immersion compared to the immersion of one finger into water of 0°C.…”

“…The cold pressor task (CPT) is widely used in studies on nociception [15,17,19,20,27,46,47] and SSp [1,18,19,27,38,46,47]. In CPT a body part is irritated by noxious cold (water).…”

Spatial summation of pain is associated with pain expectations: Results from a home-based paradigm

“…In the descending condition the order was reversed, i.e., they first immersed all 5 segments and finished with immersion of just 1 segment. In both conditions there was a 5 minutes break between immersion of the next segment to ensure that the skin temperature returned to baseline [21]. The order of testing (ascending vs. descending condition) was random.…”

“…The cold pressor task (CPT) is widely used in studies on nociception [2,[15][16][17][18][19][20] and SSp [2,[18][19][20][21][22][23]. In CPT, a body part is immersed into cold water serving as a noxious stimulus.…”