Laminar distribution and the response of superior colliculus neurons to stimulation of the periodontal ligament in the rabbit.
Unit discharges of superior colliculus neurons fired by electrical stimulation of the periodontal ligament and/or mechanical stimulation of the mandibular incisor tooth were extracellularly recorded, and their laminar distribution and response properties were examined. The neurons were widely distributed in the deep layer of the anterior two-thirds of the superior colliculus. Most of them were located in the lateral site of the profound layer, a few in the lateral site of the intermediate layer. Their locations correspond to the lower nasal quadrant of the visual field. The mean first-spike latency of the intermediate layer neurons (7.2 ms) elicited by electrical stimulation of the periodontal ligament was shorter than that of the profound-layer neurons (13.8 ms). About one-third of the neurons were suppressed by conditioning electrical stimulation of the optic chiasma. These results suggested that in addition to visual, auditory, and body surface tactile sensations, intraoral somesthetic sensations also participate in the functioning of the superior colliculus which appears to play a role in orienting the animal toward visual, somesthetic, and auditory stimuli.
D000818:Animals; D004558:Electric Stimulation; D007180:Incisor / Q000294:innervation / Q000502:physiology; D008465:Mechanoreceptors / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology; D009897:Optic Chiasm / Q000502:physiology; D010513:Periodontal Ligament / Q000294:innervation* / Q000502:physiology; D011434:Proprioception; D011817:Rabbits; D012677:Sensation / Q000502:physiology; D013477:Superior Colliculi / Q000502:physiology*