Noxious visceral inputs enhance cutaneous tactile response in rat thalamus

Intradermal injection of capsaicin induces acute substance P release from rat spinal cord dorsal horn.

The responses of dorsal horn neurons to somatosensory stimulation can be altered under a variety of circumstances. For example, somatosensory responses of spinal cord dorsal horn neurons can be decreased by 1) habituation following repeated stimulation of the excitatory receptive field;46 2) stimulation of an inhibitory receptive field;30 3) activity in descending inhibitory pathways81 and 4) pathological changes leading to loss of primary afferent fibers.13 Conversely, somatosensory responses can be increased by such manipulations as 1) repeated stimulation of fine calibre primary afferent fibers (“wind-up”);47 2) spatial summation of excitatory inputs from different parts of the receptive field;49 3) volleys in excitatory pathways descending from the brain;80 and 4) sensitization of primary afferent fibers37 or of dorsal horn neurons as a consequence of damage to peripheral tissue or peripheral nerves.19,57

W. D. WillisJr.

Papers

Dynamic Changes in Dorsal Horn Neurons