Touch inhibits subcortical and cortical nociceptive responses
نویسندگان
چکیده
The neural mechanisms of the powerful analgesia induced by touching a painful body part are controversial. A long tradition of neurophysiologic studies in anaesthetized spinal animals indicate that touch can gate nociceptive input at spinal level. In contrast, recent studies in awake humans have suggested that supraspinal mechanisms can be sufficient to drive touch-induced analgesia. To investigate this issue, we evaluated the modulation exerted by touch on established electrophysiologic markers of nociceptive function at both subcortical and cortical levels in humans. Aδ and C skin nociceptors were selectively activated by high-power laser pulses. As markers of subcortical and cortical function, we recorded the laser blink reflex, which is generated by brainstem circuits before the arrival of nociceptive signals at the cortex, and laser-evoked potentials, which reflect neural activity of a wide array of cortical areas. If subcortical nociceptive responses are inhibited by concomitant touch, supraspinal mechanisms alone are unlikely to be sufficient to drive touch-induced analgesia. Touch induced a clear analgesic effect, suppressed the laser blink reflex, and inhibited both Aδ-fibre and C-fibre laser-evoked potentials. Thus, we conclude that touch-induced analgesia is likely to be mediated by a subcortical gating of the ascending nociceptive input, which in turn results in a modulation of cortical responses. Hence, supraspinal mechanisms alone are not sufficient to mediate touch-induced analgesia.
منابع مشابه
Whole-brain functional magnetic resonance imaging mapping of acute nociceptive responses induced by formalin in rats using atlas registration-based event-related analysis.
Nociceptive neuronal activation in subcortical regions has not been well investigated in functional magnetic resonance imaging (fMRI) studies. The present report aimed to use the blood oxygenation level-dependent (BOLD) fMRI technique to map nociceptive responses in both subcortical and cortical regions by employing a refined data processing method, the atlas registration-based event-related (A...
متن کاملSeeing touch and pain in a stranger modulates the cortical responses elicited by somatosensory but not auditory stimulation.
Viewing other's pain inhibits the excitability of the motor cortex and also modulates the neural activity elicited by a concomitantly delivered nociceptive somatosensory stimulus. As the neural activity elicited by a transient nociceptive stimulus largely reflects non nociceptive-specific, multimodal neural processes, here we tested, for the first time, whether the observation of other's pain p...
متن کاملNociceptive Cortical Activity Is Dissociated from Nociceptive Behavior in Newborn Human Infants under Stress
Newborn infants display strong nociceptive behavior in response to tissue damaging stimuli, and this is accompanied by nociceptive activity generated in subcortical and cortical areas of the brain [1, 2]. In the absence of verbal report, these nociceptive responses are used as measures of pain sensation in newborn humans, as they are in animals [3, 4]. However, many infants are raised in a phys...
متن کاملDifferent Profiles of Verbal and Nonverbal Auditory Impairment in Cortical and Subcortical Lesions
A B S T R A C T Introduction:We investigated differential role of cortical and subcortical regions in verbal and non-verbal sound processing in ten patients who were native speakers of Persian with unilateral cortical and/or unilateral and bilateral subcortical lesions and 40 normal speakers as control subjects. Methods: The verbal tasks included monosyllabic, disyllabic dichotic and diotic tas...
متن کاملSilent subcortical brain infarction
Introduction: The silent brain lesions detected by MRI were fairly common not only in first-ever stroke but also in normal elderly subjects. Some recent studies show the possible role of silent sub-cortical brain infarction in ischemic stroke. The aim of this study was to evaluate the frequency of silent sub-cortical brain infarction in acute first-ever ischemic stroke. Methods: In this descrip...
متن کامل