Journal of neurophysiology
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Single-unit electrical activity has been recorded from 122 viscerosomatic neurons in the T9 and T11 segments of the cat's spinal cord. These neurons were excited by electrical and/or natural stimulation of visceral and somatic afferent fibers. The majority of viscerosomatic neurons (72%) received somatic nociceptive inputs, either exclusively or together with low-threshold somatic inputs. ⋯ Sixteen percent of all viscerosomatic neurons tested showed no change in their responses to visceral stimulation during spinalization. It is concluded that the visceral input to viscerosomatic neurons in the lower thoracic spinal cord is under considerable descending control, which includes excitation as well as tonic inhibition of visceral afferent information. This may represent part of the widespread effects of visceral nociceptive stimulation.