No abstract

Touch plays a significant role in human social behavior and social communication, and its rewarding nature has been suggested to involve opioids. Opioid blockade in monkeys leads to increased solicitation and receipt of grooming, suggesting heightened enjoyment of touch. We sought to study the role of endogenous opioids in perception of affective touch in healthy adults and in patients with fibromyalgia, a chronic pain condition shown to involve reduced opioid receptor availability. The pleasantness of touch has been linked to the activation of C-tactile fibers, which respond maximally to slow gentle touch and correlate with ratings of pleasantness. We administered naloxone to patients and healthy controls to directly observe the consequences of -opioid blockade on the perceived pleasantness and intensity of touch. We found that at baseline chronic pain patients showed a blunted distinction between slow and fast brushing for both intensity and pleasantness, suggesting reduced C-tactile touch processing. In addition, we found a differential effect of opioid blockade on touch perception in healthy subjects and pain patients. In healthy individuals, opioid blockade showed a trend toward increased ratings of touch pleasantness, while in chronic pain patients it significantly decreased ratings of touch intensity. Further, in healthy individuals, naloxone-induced increase in touch pleasantness was associated with naloxone-induced decreased preference for slow touch, suggesting a possible effect of opioid levels on processing of C-tactile fiber input. These findings suggest a role for endogenous opioids in touch processing, and provide further evidence for altered opioid functioning in chronic pain patients.Key words: affective touch; C-tactile fibers; chronic pain; fibromyalgia; opioids; somatosensation Significance Statement C-tactile fibers are normally more activated by slow gentle touch than by fast touch and send a signal to the brain that contributes to the perception of pleasantness. This paper shows that people with the chronic pain condition fibromyalgia perceive less difference between fast and slow gentle touch in terms of its intensity and pleasantness, suggesting reduced C-tactile fiber processing and/or differences in opioid signaling. Our paper is also the first demonstration in humans that opioids affect how touch feels. In healthy individuals, blocking opioid binding tended to increase touch pleasantness, whereas in fibromyalgia patients it decreased perceived intensity. This suggests a role for endogenous opioids in touch perception, and provides new evidence that opioids function differently in chronic pain.

Objective: Several issues concerning F2 slope in dysarthria were addressed by obtaining speech acoustic measures and judgments of intelligibility for sentences produced in Habitual, Clear and Loud conditions by speakers with Parkinson's disease (PD) and healthy controls. Patients and Methods: Acoustic measures of average and maximum F2 slope for diphthongs, duration and intensity were obtained. Listeners judged intelligibility using a visual analog scale. Differences in measures among groups and conditions as well as relationships among measures were examined. Results: Average and maximum F2 slope metrics were strongly correlated, but only average F2 slope consistently differed among groups and conditions, with shallower slopes for the PD group and steeper slopes for Clear speech versus Habitual and Loud. Clear and Loud speech were also characterized by lengthened durations, increased intensity and improved intelligibility versus Habitual. F2 slope and intensity were unrelated, and F2 slope was a significant predictor of intelligibility. Conclusion: Average diphthong F2 slope was more sensitive than maximum F2 slope to articulatory mechanism involvement in mild dysarthria in PD. F2 slope holds promise as an objective measure of treatment-related changes in the articulatory mechanism for therapeutic techniques that focus on articulation.

There is preclinical and clinical evidence that vagus nerve stimulation modulates both pain and mood state. Mechanistic studies show brainstem circuitry involved in pain modulation by vagus nerve stimulation, but little is known about possible indirect descending effects of altered mood state on pain perception. This possibility is important, since previous studies have shown that mood state affects pain, particularly the affective dimension (pain unpleasantness). To date, human studies investigating the effects of vagus nerve stimulation on pain perception have not reliably measured psychological factors to determine their role in altered pain perception elicited by vagus nerve stimulation. Thus, it remains unclear how much of a role psychological factors play in vagal pain modulation. Here, we present a rationale for including psychological measures in future vagus nerve stimulation studies on pain.