Convergence of Visceral and Somatic Nociceptive Inputs onto Hippocampal Units in Cats / 第三军医大学学报

ABSTRACT

Ten cats lightly anesthetized and D-tubocurarine immobilized were employed.The responses of a same unit to the train stimuli of square wave applied to the saphenous nerve,the greater splanchic nerve,and the two nerves simultaneously were observed.Among the 80 units recorded on the 10 cats,43 went through all the experimental procedures,33 out of the 43 could be activated by splanchic inputs.Convergence of the splanchic and saphenous inputs occurred to 26(79％) out of the 33.These 26 units could respond to the noxious stimuli on the saphenous and greater splanchic nerves in turn or simultaneously.Furthermore,they could be divided into 3 types;15 units showed similar pattern and duration of discharge only when the greater splanchic nerve was stimulated,6 showed similar discharge only when the saphenous nerve was stimulated,and 5 showed smaller responses when either of the two nerves was stimulated.When the interval between stimulations was shortened to 5 seconds,37(86％) out of the 43 units showed a decrease in discharge,which was apparently an after-inhibitory effect.The results indicate that the inputs from visceral and somatic C or A-delta afferent fibers can converge onto the units of the dorsal hippocampal CA1 area,and evoke blockage and inhibition of these units.