253) Neural Moderators Supporting the Positive Relationship between Resting Breathing Rate and Pain Responses

Inter-individual differences in pain are shaped by a myriad of interactions between physiological, cognitive-affective and psychosocial factors. Interestingly, recent findings demonstrate that slow breathing-based manipulations reduce pain. Yet, it is unknown if non-manipulated, resting breathing rate predicts variability in behavioral and neural pain responses. The proposed study, part of a previously published dataset, examined if non-manipulated, slow breathing during noxious (heat = 49°C) and innocuous (neutral = 35°C) heat predicted lower pain. We postulated that subcortical respiration centers (brainstem) would moderate this hypothesized relationship. Seventy-four healthy, pain-free individuals were fitted with a respiratory transducer and administered two neutral and two heat series to the right calf during pseudo-continuous arterial spin labeling fMRI. After each fMRI series, participants provided pain intensity and unpleasantness ratings using a visual analog scale (0 = no pain – 10 = worst pain imaginable). Lower respiration rate was associated with lower pain intensity ( r  = .29, p  = .01) and unpleasantness ( r  = .25, p  = .03) ratings. Compared to innocuous stimulation, noxious heat produced significant activation in the bilateral thalamus, posterior/anterior insula, secondary somatosensory cortices (SII), primary somatosensory cortex (SI) corresponding to the stimulation site, and deactivation of the medial prefrontal (mPFC) and posterior cingulate cortex. Greater superior frontal gyrus and mPFC activation was associated with lower pain unpleasantness ratings. Two separate moderation analyses were conducted on respiration rate and pain intensity and unpleasantness, respectively. There were no significant neural moderators between pain intensity and respiration. High activation of the bilateral SI, contralateral SII, and ipsilateral superior parietal lobe moderated the positive relationship between respiration and pain unpleasantness. This study provides novel evidence that inter-individual differences in breathing predict pain responses and are moderated by brain mechanisms supporting the allocation of attention to intrinsic and extrinsic features of the pain experience.