The interactions between spatial summation and DNIC: Effect of the distance between two painful stimuli and attentional factors on pain perception

Abstract

The ability of a painful stimulus to suppress pain in another, remote area (DNIC) has been intensely studied. However, the effect of the distance between the two painful stimuli and the attentional factors during the measurement of pain perception received minimal treatment. We evaluated the effect of these factors on DNIC and on the interaction between DNIC and spatial summation (SS) of pain. Subjects rated the intensity of a test stimulus (applied to one hand) alone and simultaneously with conditioning stimuli applied to four different locations; 5 and 30cm from the test stimulus on the same hand, the contralateral hand and contralateral leg. In each location, ratings were performed under three different instructions: summation, attention to test stimulus, attention to conditioning stimulus. The distance between the conditioning and test stimulus significantly affected pain perception (p<0.01) regardless of the instructions; SS occurred only at a distance of 5cm and DNIC occurred only in the remaining distances. DNIC's magnitude increased as the distance between the two stimuli increased (p<0.01). However, the instruction to summate attenuated DNIC and the DNIC instruction attenuated SS of pain. Attention to the conditioning stimulus induced a stronger DNIC than attention to the test stimulus (p<0.001). We conclude that (1) DNIC and SS of pain appear to be antagonistic processes. (2) DNIC is affected by the distance between two noxious stimuli and to a lesser extent, by attention. (3) The interaction between DNIC, SS and attention is complex and reflects the role of sensory-cognitive integration in pain perception.

Deficient Pain Modulatory Systems in Patients with Mild Traumatic Brain and Chronic Post-Traumatic Headache: Implications for its Mechanism

“…This distance between the test and conditioning stimulus was reported to produce the most intense CPM. 35 The test stimulus was PPT measured with the pressure algometer as described previously. The conditioning stimulus was noxious heat, applied with the thermal stimulator, at an intensity of 2°C above individual HPT measured as described previously for a duration of 60 sec.…”

“…The magnitude of CPM was calculated by subtracting the PPT measured in the presence of the conditioning stimulus from the PPT measured alone. 35 Questionnaires and additional data collection TBI. All patients with TBI were interviewed regarding their injury, including the date and their age at the time of injury, causes and circumstances, additional injuries that incurred with the main injury, and comorbidities.…”

Acute psychosocial stress reduces pain modulation capabilities in healthy men

“…The second application of the test stimulus occurred 15 seconds after the application of the conditioning stimulus. The magnitude of CPM was calculated by subtracting the VAS rating of the test stimulus in the presence of the conditioning stimulus from the VAS rating of the test stimulus alone [21].…”

Effects of Motor Cortex Modulation and Descending Inhibitory Systems on Pain Thresholds in Healthy Subjects

“…Furthermore, the influence of attentional factors in modulating DNIC's effect on pain when combined with the tDCS ought to be explored. 9 Of note, our current design includes DNIC administration during the assessments both before and after tDCS administration. Our study assumes that there is no DNIC carryover effects when assessing thresholds immediately following tDCS administration.…”