Squirrel monkey lateral thalamus. II. Viscerosomatic convergent representation of urinary bladder, colon, and esophagus

Johannes Brüggemann, Ting Shi, A. Vaina Apkarian*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

67 Scopus citations

Abstract

The response properties of 106 visceroceptive lateral thalamic neurons were investigated in anesthetized squirrel monkeys. Most neurons were located in the ventral posterior lateral nucleus (VPL), and a smaller number of cells was also found in a variety of thalamic nuclei around VPL. Ninety (85%) of these cells responded to distension of the urinary bladder, the distal colon, and/or the lower esophagus. The majority of the visceral-responsive cells also had convergent somatic and multivisceral responses (71% of the 85%). A small population (6%) was visceral specific; that is, these neurons were not activated with somatic stimuli. Visceral responses were excitatory, inhibitory, or mixed, and most were either visceral nociceptive specific (65%) or visceral wide-dynamic-range type (34%). Very few visceral responses (1%) could be classified as low threshold. The incidence of these response types were highly dependent on the specific viscus stimulated. Most visceral responses were able to code stimulus duration and intensity. The majority (69%) of the visceroceptive neurons had somatic low-threshold convergent input mainly from the surface of the lower body. The somatic receptive field locations and the somatic response properties seem unrelated to the convergent visceral input and the visceral response properties, although there were some exceptions. No obvious viscerotopical organization was found in VPL. The results lead us to propose two different modes of representation for processing of and distinguishing between visceral and somatic inputs: a distributed population code for visceral inputs, and a local code for somatic inputs. Based on these codes, we discuss a new hypothesis for referred pain.

Original languageEnglish (US)
Pages (from-to)6796-6814
Number of pages19
JournalJournal of Neuroscience
Volume14
Issue number11 II
DOIs
StatePublished - 1994

Keywords

  • VPL
  • distributed coding
  • electrophysiology
  • nociception
  • pain
  • referred pain
  • ventral posterior nuclei
  • visceral

ASJC Scopus subject areas

  • Neuroscience(all)

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