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Z .Brain Research 787 1998 269276 Research report

Summary: Z .Brain Research 787 1998 269276
Research report
Viscerosomatic interactions in the thalamic ventral posterolateral nucleus
Z .VPL of the squirrel monkey
Johannes Bruggemann, Ting Shi, A. Vania Apkarian )

Department of Neurosurgery, Computational Neuroscience Program, SUNY Health Science Center at Syracuse, Syracuse, NY 13210, USA
Accepted 9 December 1997
In anesthetized squirrel monkeys single cell recordings were performed using tungsten microelectrodes. The responses of 29
viscerosomatoceptive and somatoceptive VPL neurons to noxious distension of the urinary bladder, the lower esophagus and the distal
colon and to innocuous and noxious somatic stimuli were assessed when these stimuli were presented separately or together. Neuronal
responses were defined as additive or interactive depending on the relative changes in responses to individual somatic or visceral stimuli,
Z .and on their responses during conditioning somatic and visceral stimuli applied concurrently . In 13 neurons interactions between the
somatosensory and visceral inputs could be demonstrated. The dominant interactive effect was inhibition, although facilitatory effects
Z .were seen as well 2 of 13 . The magnitude or direction of the interactions seemed independent of the location of the somatic and visceral
receptive fields. The mean population response of the neurons showing interactions was 4.66 spikesrs to somatic stimulation, and 0.07
spikesrs to visceral stimulation. During conditioning the mean interactive effect was y62% of the calculated additive effect. This implies
that overall the somatic responses are halved during a coincident visceral stimulus. In a subgroup of the VPL neurons, which were
Z . Z .classified as pure somatic responsive ns14 due to their unresponsiveness during visceral stimulation alone, a third ns5 still


Source: Apkarian, A. Vania - Department of Physiology, Northwestern University


Collections: Biology and Medicine