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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Somatosensory and pain responses to direct intracerebral stimulations of the SII area were obtained in 14 patients referred for epilepsy surgery. Stimulations were delivered using transopercular electrodes exploring the parietal opercular cortex (SII area), the suprasylvian parietal cortex (SI area) and the insular cortex. SII responses were compared to those from adjacent SI and insular cortex. In the three areas we elicited mostly somatosensory responses, including paresthesiae, temperature and pain sensations. The rate of painful sensations (10%) was similar in SII and in the insula, while no painful sensation was evoked in SI. A few non-somatosensory responses were evoked by SII stimulation. Conversely various types of non-somatosensory responses (auditory, vegetative, vestibular, olfacto-gustatory, etc.) were evoked only by insular stimulation, confirming that SII, like SI, are mostly devoted to the processing of somatosensory inputs whereas the insular cortex is a polymodal area. We also found differences in size and lateralization of skin projection fields of evoked sensations between the three studied areas, showing a spatial resolution of the somatotopic map in SII intermediate between those found in SI and insula. This study shows the existence of three distinct somatosensory maps in the suprasylvian, opercular and insular regions, and separate pain representations in SII and insular cortex.
Cereb Cortex 2006 Jul
PMID:Somatosensory and pain responses to stimulation of the second somatosensory area (SII) in humans. A comparison with SI and insular responses. 1617 70

Event-related functional magnetic resonance imaging was used to investigate brain processing of the signals ascending from peripheral C and Adelta fibers evoked by phasic laser stimuli on the right hand in humans. The stimulation of both C and Adelta nociceptors activated the bilateral thalamus, bilateral secondary somatosensory cortex, right (ipsilateral) middle insula, and bilateral Brodmann's area (BA) 24/32, with the majority of activity found in the posterior portion of the anterior cingulate cortex (ACC). However, magnitude of activity in the right (ipsilateral) BA32/8/6, including dorsal parts in the anterior portion of the ACC (aACC) and pre-supplementary motor area (pre-SMA), and the bilateral anterior insula was significantly stronger following the stimulation of C nociceptors than Adelta nociceptors. It was concluded that the activation of C nociceptors, related to second pain, evokes different brain processing from that of Adelta nociceptors, related to first pain, probably due to the differences in the emotional and motivational aspects of either pain, which are mainly related to the aACC, pre-SMA, and anterior insula.
Cereb Cortex 2006 Sep
PMID:Brain processing of the signals ascending through unmyelinated C fibers in humans: an event-related functional magnetic resonance imaging study. 1628 Apr 63

Understanding another person's experience draws on "mirroring systems," brain circuitries shared by the subject's own actions/feelings and by similar states observed in others. Lately, also the experience of pain has been shown to activate partly the same brain areas in the subjects' own and in the observer's brain. Recent studies show remarkable overlap between brain areas activated when a subject undergoes painful sensory stimulation and when he/she observes others suffering from pain. Using functional magnetic resonance imaging, we show that not only the presence of pain but also the intensity of the observed pain is encoded in the observer's brain-as occurs during the observer's own pain experience. When subjects observed pain from the faces of chronic pain patients, activations in bilateral anterior insula (AI), left anterior cingulate cortex, and left inferior parietal lobe in the observer's brain correlated with their estimates of the intensity of observed pain. Furthermore, the strengths of activation in the left AI and left inferior frontal gyrus during observation of intensified pain correlated with subjects' self-rated empathy. These findings imply that the intersubjective representation of pain in the human brain is more detailed than has been previously thought.
Cereb Cortex 2007 Jan
PMID:The compassionate brain: humans detect intensity of pain from another's face. 1649 34

The SII area and the posterior insular region are both activated by thermal stimuli in functional imaging studies. However, controversy remains as to a possible differential encoding of thermal intensity by each of these 2 contiguous areas. Using CO(2) laser stimulations, we analyzed the modifications induced by increasing thermal energy on evoked potentials recorded with electrodes implanted within SII and posterior insula in patients referred for presurgical evaluation of epilepsy. Although increasing stimulus intensities enhanced both SII and insular responses, the "dynamics" of their respective amplitude changes were different. SII responses were able to encode gradually the intensity of stimuli from sensory threshold up to a level next to pain threshold but tended to show a ceiling effect for higher painful intensities. In contrast, the posterior insular cortex failed to detect nonnoxious laser pulses but reliably encoded stimulus intensity variations at painful levels, without showing saturation effects for intensities above pain threshold. According to these results, one can assume that insular cortex could be more involved in the triggering of affective recognition of, and motor reaction to, noxious stimuli, whereas SII would be more dedicated to finer-grain discrimination of stimulus intensity, from nonpainful to painful levels.
Cereb Cortex 2007 Mar
PMID:Human SII and posterior insula differently encode thermal laser stimuli. 1661 65

Pain is an unpleasant sensation, and at the same time, it is always subjective and affective. Ten healthy subjects viewed 3 counterbalanced blocks of images from the International Affective Picture System: images showing painful events and those evoking emotions of fear and rest. They were instructed to imagine pain in their own body while viewing each image showing a painful event (the imagination of pain). Using functional magnetic resonance imaging, we compared cerebral hemodynamic responses during the imagination of pain with those to emotions of fear and rest. The results show that the imagination of pain is associated with increased activity in several brain regions involved in the pain-related neural network, notably the anterior cingulate cortex (ACC), right anterior insula, cerebellum, posterior parietal cortex, and secondary somatosensory cortex region, whereas increased activity in the ACC and amygdala is associated with the viewing of images evoking fear. Our results indicate that the imagination of pain even without physical injury engages the cortical representations of the pain-related neural network more specifically than emotions of fear and rest; it also engages the common representation (i.e., in ACC) between the imagination of pain and the emotion of fear.
Cereb Cortex 2007 May
PMID:Inner experience of pain: imagination of pain while viewing images showing painful events forms subjective pain representation in human brain. 1685 7

Pain naturally draws one's attention. However, humans are capable of engaging in cognitive tasks while in pain, although it is not known how the brain represents these processes concurrently. There is some evidence for a cortical interaction between pain- and cognitive-related brain activity, but the outcome of this interaction may depend on the relative load imposed by the pain versus the task. Therefore, we used 3 levels of cognitive load (multisource interference task) and 2 levels of pain intensity (median nerve stimulation) to examine how functional magnetic resonance imaging activity in regions identified as pain-related or cognitive-related responds to different combinations of pain intensity and cognitive load. Overall, most pain-related or cognitive-related brain areas showed robust responses with little modulation. However, during the more intense pain, activity in primary sensorimotor cortex, secondary somatosensory cortex/posterior insula, anterior insula, paracentral lobule, caudal anterior cingulate cortex, cerebellum, and supplementary motor area was modestly attenuated by the easy task and in some cases the difficult task. Conversely, cognitive-related activity was not modulated by pain, except when cognitive load was minimal during the control task. These findings support the notion that brain networks supporting pain perception and cognition can be simultaneously active.
Cereb Cortex 2007 Jun
PMID:Interactions of pain intensity and cognitive load: the brain stays on task. 1690 93

This study investigates the antinociceptive effect of intracerebroventricular (i.c.v.) injection of cytidine-5'-diphosphate choline (CDP-choline; citicoline) and the involvement of cholinergic mechanisms in rats. Three different pain models were utilized: thermal paw withdrawal test, mechanical paw pressure test and acetic acid writhing test. The i.c.v. administration of CDP-choline (0.5, 1.0 and 2.0 micromol) produced dose and time-dependent antinociception. Equimolar dose of choline (1 micromol; i.c.v.) produced antinociceptive response similar to the one observed in CDP-choline given animals. On the other hand, cytidine (1 micromol; i.c.v.) failed to produce response in the thermal paw withdrawal test and the mechanical paw pressure test but in the writhing test in which it produced significant antinociceptive effect. CDP-choline-induced antinociception was prevented by the neuronal high affinity choline uptake inhibitor HC-3 (1 microg; i.c.v.), the nonselective nicotinic receptor antagonist mecamylamine (50 microg; i.c.v.) and by the alpha(7)-selective nicotinic receptor antagonist, MLA (25 microg; i.c.v.). However, it was not changed by the nonselective muscarinic receptor antagonist atropine (10 microg; i.c.v.) in the thermal paw withdrawal test and mechanical paw pressure test. In the writhing test, all antagonist pretreatments produced blockade similar to that obtained from CDP-choline injected animals. CDP-choline did not impair the motor performance of rats as evaluated by a rota-rod test. Therefore, it can be postulated that CDP-choline exerts an antinociceptive effect mediated by a central cholinergic mechanism. Activation of specific alpha(7)-nicotinic cholinergic receptors through the activation of presynaptic cholinergic mechanisms appears to be involved in the antinociceptive effect of this drug.
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PMID:The antinociceptive effects of centrally administered CDP-choline on acute pain models in rats: the involvement of cholinergic system. 1694 53

Noxious stimulation of skeletal muscle evokes pain that is often referred into distal areas. Despite referred pain being of significant clinical importance, the brain regions responsible for the perception of referred pain remain unexplored. The aim of this investigation is to define these regions using functional magnetic resonance imaging. We induced muscle pain by hypertonic saline injections (0.5 ml) into the tibialis anterior (TA) or flexor carpi radialis (FCR) muscle. TA injections evoked pain that was referred to the ankle/foot in 10/17 subjects, whereas FCR injections evoked pain that was projected into the wrist/hand in 6/12 subjects. Regional brain responses were statistically tested by convolving the temporal profile of the subjective pain intensity rating with the hemodynamic response function. For all subjects, signal increased in the region of primary somatosensory cortex (SI), which represents the leg or arm, that is, the area corresponding to the injection site. However, for those subjects who reported referred pain, signal intensity increases also occurred in the SI region representing the foot or hand. Interestingly, differential signal changes also occurred in anterior cingulate, cerebellar, and insular cortices. This is the first study to provide evidence of cortical differentiation in the processing of primary and referred pain.
Cereb Cortex 2007 Sep
PMID:Discrete changes in cortical activation during experimentally induced referred muscle pain: a single-trial fMRI study. 1710 89

Neuroimaging evidence has shown that a network including cingulate cortex and bilateral insula responds to both felt and seen pain. Of these, dorsal anterior cingulate and midcingulate areas are involved in preparing context-appropriate motor responses to painful situations, but it is unclear whether the same holds for observed pain. Participants in this functional magnetic resonance imaging study viewed short animations depicting a noxious implement (e.g., a sharp knife) or an innocuous implement (e.g., a butter knife) striking a person's hand. Participants were required to execute or suppress button-press responses depending on whether the implements hit or missed the hand. The combination of the implement's noxiousness and whether it contacted the hand strongly affected reaction times, with the fastest responses to noxious-hit trials. Blood oxygen level-dependent signal changes mirrored this behavioral interaction with increased activation during noxious-hit trials only in midcingulate, dorsal anterior, and dorsal posterior cingulate regions. Crucially, the activation in these cingulate regions also depended on whether the subject made an overt motor response to the event, linking their role in pain observation to their role in motor processing. This study also suggests a functional topography in medial premotor regions implicated in "pain empathy," with adjacent activations relating to pain-selective and motor-selective components, and their interaction.
Cereb Cortex 2007 Sep
PMID:The sight of others' pain modulates motor processing in human cingulate cortex. 1712 86

Because awareness of emotional states in the self is a prerequisite to recognizing such states in others, alexithymia (ALEX), difficulty in identifying and expressing one's own emotional states, should involve impairment in empathy. Using functional magnetic resonance imaging (fMRI), we compared an ALEX group (n = 16) and a non-alexithymia (non-ALEX) group (n = 14) for their regional hemodynamic responses to the visual perception of pictures depicting human hands and feet in painful situations. Subjective pain ratings of the pictures and empathy-related psychological scores were also compared between the 2 groups. The ALEX group showed less cerebral activation in the left dorsolateral prefrontal cortex (DLPFC), the dorsal pons, the cerebellum, and the left caudal anterior cingulate cortex (ACC) within the pain matrix. The ALEX group showed greater activation in the right insula and inferior frontal gyrus. Furthermore, alexithymic participants scored lower on the pain ratings and on the scores related to mature empathy. In conclusion, the hypofunction in the DLPFC, brain stem, cerebellum, and ACC and the lower pain-rating and empathy-related scores in ALEX are related to cognitive impairments, particularly executive and regulatory aspects, of emotional processing and support the importance of self-awareness in empathy.
Cereb Cortex 2007 Sep
PMID:Empathy and judging other's pain: an fMRI study of alexithymia. 1715 Sep 87


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