T-DCS Effects on Endogenous Pain Modulation
pain
This is the first study assessing the effect of cerebellar t-DCS on measures of endogenous pain modulation, namely, the RIII, OA, and CPM. We found an increase in RIII reflex area immediately after cathodal t-DCS and an increase in offset analgesia after anodal t-DCS, but no effect on CPM. These results again must be viewed with caution because they were evident only in the exploratory analysis.The RIII reflex is a spinally mediated nociceptive reflex modulated by descending pain inhibitory pathways [Previous animal studies have shown that electrical or chemical stimulation of the cerebellum alters responses of spinal nociceptive neurons [In summary, two of three measures of endogenous pain modulation suggested that cathodal cerebellar t-DCS reduces while anodal t-DCS increases endogenous (possibly descending) pain inhibition. Together, the present and previous results would be consistent with the hypothesis that cerebellar activation reduces pain perception via probably an effect on endogenous/descending pain inhibitory pathways while cerebellar inhibition does the opposite. This would be an expansion of the notion that reduction of pain perception by anodal (excitatory) cerebellar t-DCS is due to strengthening of the tonic inhibitory cerebellar influence over cortical areas (“cerebellar brain inhibition”) [