Neuroreport
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We analyzed, with a new imaging technique, the rapid axon reflex flare responses in human skin upon transcutaneous delivery of electrical stimuli at 1, 5, 10 and 50 Hz in single bursts of five pulses each. Two-dimensional perfusion images covering an area of 8 x 8 cm(2) were captured at 25 Hz and their averages saved at 0.5 Hz. ⋯ Maximum flare responses developed at 5 Hz, whereas pain ratings increased with stimulation frequency. The highest neuropeptide release at 5 Hz correlates to the discharge characteristics of mechanoinsensitive C-fibers, whereas the maximum pain intensity at 50 Hz may be attributed to the activation of A-delta fibers.
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The development of human social cognition has allowed interactions with other species and the formation of a cooperative multi-species society. This feature posited keen attention on the following question: is heterospecific social cognition represented in the same brain areas as conspecific social cognition? Here we investigated brain activity accompanying the facial recognition of familiar humans and of companion dogs, both of whom had real social interactions with participants. The rostroventral anterior cingulate cortex responded to both species whereas the caudal anterior cingulate cortex was sensitive only to familiar humans. Social cognition processes may be dual-layered: the rostroventral anterior cingulate cortex is associated with fundamental and intuitive aspects, whereas the caudal anterior cingulate cortex is concerned with the analysis of complex social interactions.