Sheng li ke xue jin zhan [Progress in physiology]
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Sheng Li Ke Xue Jin Zhan · Oct 2007
Review[Alternative tactile system: C-fibers coding the affective aspect].
It has been accepted that human tactile sensation is mediated exclusively by large myelinated (Abeta) fibres. Nevertheless, recent studies indicated a dual mechanoceptive innervation of the skin in various mammals. Besides the known A fibers, the skin is also innervated by slow-conducting, low-threshold, small unmyelinated (C) afferents. ⋯ Functional magnetic resonance imaging (fMRI) studies showed that a slowly moving tactile stimulus along hairy skin produced a strong activation of the insular cortex. Pleasant touch has also been demonstrated to activate orbitofrontal cortex adjacent to areas responding to pleasant taste and smell. Overall, the response characteristics and activated brain regions suggest that they are related with the limbic system and affective aspect rather than tactile discriminative function.