Article

Pain perception: is there a role for primary somatosensory cortex? Proc Natl Acad Sci USA

McGill University and Université de Montréal, Montreal, Quebec, Canada H3A 1A1.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 08/1999; 96(14):7705-9. DOI: 10.1073/pnas.96.14.7705
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ABSTRACT Anatomical, physiological, and lesion data implicate multiple cortical regions in the complex experience of pain. These regions include primary and secondary somatosensory cortices, anterior cingulate cortex, insular cortex, and regions of the frontal cortex. Nevertheless, the role of different cortical areas in pain processing is controversial, particularly that of primary somatosensory cortex (S1). Human brain-imaging studies do not consistently reveal pain-related activation of S1, and older studies of cortical lesions and cortical stimulation in humans did not uncover a clear role of S1 in the pain experience. Whereas studies from a number of laboratories show that S1 is activated during the presentation of noxious stimuli as well as in association with some pathological pain states, others do not report such activation. Several factors may contribute to the different results among studies. First, we have evidence demonstrating that S1 activation is highly modulated by cognitive factors that alter pain perception, including attention and previous experience. Second, the precise somatotopic organization of S1 may lead to small focal activations, which are degraded by sulcal anatomical variability when averaging data across subjects. Third, the probable mixed excitatory and inhibitory effects of nociceptive input to S1 could be disparately represented in different experimental paradigms. Finally, statistical considerations are important in interpreting negative findings in S1. We conclude that, when these factors are taken into account, the bulk of the evidence now strongly supports a prominent and highly modulated role for S1 cortex in the sensory aspects of pain, including localization and discrimination of pain intensity.

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Available from: Jen-I Chen, Oct 23, 2014
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    • "Spinothalamic pathways terminate in specific thalamus nuclei as the ventroposterolateral and ventroposteromedial which in turn project to SI and SII. Primary somatosensory cortex is implicated in localize pain [3], but when considering the abundance of the dorsal horn projection of myelinated afferents to it, the SI seems to support abilities of normal subjects to localize skin stimuli and discriminate between sensory attributes that include pain intensity (for review, see Ref. [26]). The SII cortex seems to have an important role in recognition, learning and memory of painful events [21]. "
    Neuroscience Letters 10/2014; 581:135–136. DOI:10.1016/j.neulet.2014.08.013 · 2.06 Impact Factor
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    • "The primary somatosensory cortex (S1) plays an important role in touch, proprioception, and pain perception [Bodegard et al., 2000; Bushnell et al., 1999; Liu et al., 2003; Moore et al., 2000; Pleger et al., 2003; Porro et al., 2004; Ragert et al., 2008]. Lesions in S1 cortex can result in fundamental functional losses in all forms of touch [Bohlhalter et al., 2002; Estanol et al., 2008; LaMotte and Mountcastle , 1979; Xerri et al., 2004; Zainos et al., 1997]. "
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    ABSTRACT: Inter-areal and ipsilateral cortical responses to tactile stimulation have not been well described in human S1 cortex. By taking advantage of the high signal-to-noise ratio at 7 T, we quantified blood oxygenation level dependent (BOLD) response patterns and time courses to tactile stimuli on individual distal finger pads at a fine spatial scale, and examined whether there are inter-areal (area 3b versus area 1) and interhemispheric response differences to unilateral tactile stimulation in healthy human subjects. We found that 2-Hz tactile stimulation of individual fingertips evoked detectable BOLD signal changes in both contralateral and ipsilateral area 3b and area 1. Contralateral digit activations were organized in an orderly somatotopic manner, and BOLD responses in area 3b were more digit selective than those in area 1. However, the area of cortex that was responsive to stimulation of a single digit (stimulus-response field) was similar across areas. In the ipsilateral hemisphere, response magnitudes in both areas 3b and 1 were significantly weaker than those of the contralateral hemisphere. Digit activations exhibited no clear somatotopic organizational pattern in either area 3b or area 1, yet digit selectivity was retained in area 1 but not in area 3b. The observation of distinct digit-selective responses of contralateral area 3b versus area 1 supports a higher order function of contralateral area 1 in spatial integration. In contrast, ipsilateral cortices may play a less discriminative role in the perception of unilateral tactile sensation in humans. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.
    Human Brain Mapping 09/2014; 35(9). DOI:10.1002/hbm.22517 · 6.92 Impact Factor
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    • "Spinothalamic pathways terminate in specific thalamus nuclei as the ventroposterolateral and ventroposteromedial which in turn project to SI and SII. Primary somatosensory cortex is implicated in localize pain [3], but when considering the abundance of the dorsal horn projection of myelinated afferents to it, the SI seems to support abilities of normal subjects to localize skin stimuli and discriminate between sensory attributes that include pain intensity (for review, see Ref. [26]). The SII cortex seems to have an important role in recognition, learning and memory of painful events [21]. "
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