Location and properties of dorsal horn neurons at origin of spinoreticular tract in lumbar enlargement of the rat

摘要: 1. Spinoreticular tract neurons at the rat lumbar cord level were identified by antidromic activation following stimulation mainly pontine and mesencephalic levels. These units, which found in dorsal half of cord, could be separated into two groups according to their spinal location, electrophysiological properties, central projections. 2. Units dorsolateral funiculus nucleus projected cuneiformis area adjacent structures with frequent bilateral They had slowest conduction velocities, sometimes unmyelinated range. Generally, they driven only subcutaneous and/or deep structures. 3. Neurons located horn contralaterally velocities properties identical those observed for spinothalamic (22). Almost all (86%) clear cutaneous sensitivity generally large receptive fields: 40% responded nonnoxious noxious mechanical stimuli frequently radiant heat, 26% exclusively excited light tactile stimuli, 20% required activation. There was a good correlation between responses natural transcutaneous electrical stimulation: units received A-delta- C-fiber inputs. The remaining (14%) more complex fields associated both excitatory inhibitory inputs originating from single peripheral area. 4. functional heterogeneity spinoreticular is reminiscent that demonstrated monkey tracts. Similarly, are under influence descending controls raphe magnus bulbar reticular formation. 5. Responses consistent involvement this pathway transmission messages innocuous origins.