Movement suppression during anesthesia: Neural projections from the mesopontine tegmentum to areas involved in motor control

Inna Sukhotinsky, David A. Hopkins, Jun Lu, Clifford B. Safer, Marshall Devor*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

Microinjection of pentobarbital and GABAA-receptor agonists into a brainstem region we have called the mesopontine tegmental anesthesia area (MPTA; Devor and Zalkind [2001] Pain 94:101-112) induces a general anesthesia-like state. As in systemic general anesthesia, rats show loss of the righting reflex, atonia, nonresponsiveness to noxious stimuli, and apparent loss of consciousness. GABAA agonist anesthetics acting on the MPTA might suppress movement by engaging endogenous motor regulatory systems previously identified in research on decerebrate rigidity and REM sleep atonia. Anterograde and retrograde tracing revealed that the MPTA has multiple descending projections to pontine and medullary areas known to be associated with motor control and atonia. Prominent among these are the dorsal pontine reticular formation and components of the rostral ventromedial medulla (RVM). The MPTA also has direct projections to the intermediate gray matter and ventral horn of the spinal cord via the lateral and anterior funiculi. These projections show a rostrocaudal topography: neurons in the rostral MPTA project to the RVM, but only minimally to the spinal cord, while those in the caudal MPTA project to both targets. Finally, the MPTA has ascending projections to motor control areas including the substantia nigra, subthalamic nucleus, and the caudate-putamen. Projections are bilateral with an ipsilateral predominance. We propose that GABAA agonist anesthetics induce immobility at least in part by acting on these endogenous motor control pathways via the MPTA. Analysis of MPTA connectivity has the potential for furthering our understanding of the neural circuitry responsible for the various functional components of general anesthesia.

Original languageEnglish
Pages (from-to)425-448
Number of pages24
JournalJournal of Comparative Neurology
Volume489
Issue number4
DOIs
StatePublished - 5 Sep 2005

Keywords

  • AAV-GFP
  • BDA
  • Coma
  • CTB
  • Loss of consciousness
  • MPTA
  • Pentobarbital
  • Reticular formation
  • Righting reflex

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