Long‐term depression of pain‐related cerebral activation in healthy man: An fMRI study

Abstract

Electrical low-frequency stimulation (LFS) of cutaneous afferents reliably induces long-term depression (LTD) of nociception and pain in man. In this study LFS effects on cerebral activation were investigated by functional magnetic resonance imaging (fMRI). In 17 healthy volunteers, nociceptive fibers of right hand dorsum were electrically stimulated via a concentric electrode. Test stimulation sessions consisted of three alternating stimulation periods and rest periods. They were performed before (Pre) and after (Post) conditioning LFS (1200 stimuli, 1Hz) or 20 min break (Control). Volunteers rated sensory and affective pain perception. Before LFS, test stimulation produced activation in bilateral primary and secondary somatosensory cortex (S1,S2), insula, anterior cingulate cortex (ACC), superior temporal cortex (STG), prefrontal cortex and right inferior parietal lobule (IPL). After LFS, exclusively right IPL was activated. Contrast between Pre and Post LFS indicated significant activity decrease in bilateral S1,S2, and ACC and right insula, IPL, and STG. Pre Control and Pre LFS were not different. Activity in Control experiments remained unchanged. Sensory and affective pain rating solely decreased after LFS. Subsequent regression analysis showed significant correlation between pain relief and increased activity after LFS in ACC, anterior insula, striatum, frontal and temporal cortex. The study revealed LTD of pain-related cerebral activation, involving sensory, affective, cognitive, and attentional processes. Positive correlation between pain relief and increased brain activation after LFS may indicate involvement of endogenous pain control mechanisms in LTD. These experiments may help to judge the potency of LTD for future chronic pain treatment.

Analgesia to pressure–pain develops in the ipsilateral forehead after high- and low-frequency electrical stimulation of the forearm

“…In addition, electricallyevoked pain decreased over the course of LFS (Klein et al 2004;Rottmann et al 2008), consistent with activation of central inhibitory pain control mechanisms (Jung et al 2012;Rottmann et al 2010) and/or long-term depression in central pain processing pathways (Klein et al 2004). Thus, local and spinal responses to electrical stimulation differed markedly between the HFS and LFS conditions.…”

Structural Brain Anomalies and Chronic Pain: A Quantitative Meta-Analysis of Gray Matter Volume

“…However, STG is active in many induced pain studies. 7,23-25,64,76,105 The STG has largely been ignored in pain imaging studies, likely in part because many investigators use region-of-interest analyses and also because a link between STG function and pain is not obvious.…”

Brain correlates of short‐term habituation to repetitive electrical noxious stimulation

“…After 20 min of conditioning electrical 1 Hz stimulation of Aδ fibres, only the IPL displayed activation, although the stimulus still was perceived as painful. Deactivations were not studied (Rottmann et al., ). This is in line with our data, in which no significant correlation between extent of habituation and S2 activity was detectable.…”