Resolution of the region of secondary somatosensory cortex that responds to stimulation of the horizontal semicircular canal in rats

Abstract

To elucidate the region within the somatosensory cortex that receives inputs from the horizontal semicircular canal (HSC) in rats, we used a multichannel recording system to measure evoked potentials in the parietal cortex in response to electrical stimulation of the HSC nerve. The recordings suggested that the HSC nerves projected bilaterally into the somatosensory cortex, with a contralateral predominance. The territory within the somatosensory cortex that responded to the stimulation of the HSC nerve was as follows: mediolateral 6.0 mm and anteroposterior -1.3 --2.3 mm from the bregma, and depth 1.4 -1.6 mm from the cortex surface horizontally by stereotaxic atlas. The evoked potential in the parietal cortex that was induced by electrical stimulation was abolished after the administration of tetrodotoxin into the oval window of the vestibular system. These results suggest that the horizontal semicircular nerve projects bilaterally into the deep layers of the secondary somatosensory cortex.

Recovery of Vestibulogastrointestinal Symptoms During Vestibular Compensation After Unilateral Labyrinthectomy in Rats

“…2) Cold-water stimulation to the external auditory canal produced tachygastria in humans (12) and tachygastria is closely related to motion sickness (16). 3) The insular cortex projects to the gastric portion in the dorsal vagal complex and inhibits gastrointestinal motility by modulating the vagovagal reflex (26), and the parietoinsular cortex receives afferent signals from the vestibular system and acts as the vestibular cortex (27,28). Thus, signals induced by UL might modulate the vagovagal reflex by the dorsal vagal complex or stimulate the sympathetic nerves by RVLM, through the vestibular nuclei, STN, cerebellum, and parietoinsular vestibular cortex (29).…”