Collateral projection from the locus coeruleus to whisker-related sensory and motor brain regions of the rat

J Comp Neurol. 2009 Jun 1;514(4):387-402. doi: 10.1002/cne.22012.

Abstract

The primary goal of this study was to examine whether the locus coeruleus (LC) provides collateral projections to whisker-related, sensorimotor brain regions. After injections of retrograde tracers into the primary sensory (S1) barrel field/primary whisker motor (M1) cortices, ventroposteromedial (VPM)/ventrolateral (VL) thalamic nuclei, or principal sensory trigeminal (Pr5)/facial motor (Mo7) nuclei, the distribution of double-labeled neurons within the LC was examined. Our observations indicated that a large number of individual LC cells provided axon collaterals to S1-M1 or VPM-VL regions, whereas only a few projected to Pr5-Mo7 nuclei. The laterality and the distribution of dual-projecting LC neurons were as follows. 1) The neurons projecting to the S1-M1 cortices were predominantly ipsilateral (96% +/- 0.7%). Labeled neurons were located ventrally at the rostral pole but were evenly distributed along the dorsoventral aspect of the principal LC. 2) The cells projecting to the VPM-VL nuclei were bilateral, with ipsilateral (68% +/- 2.3%) dominance. Neurons were observed at the rostrocaudal extent of the LC, where the labeling was most pronounced at the ventral, principal LC. 3) The neurons projecting to the Pr5-Mo7 regions exhibited slightly contralateral (56% +/- 2.9%) dominance, where labeled cells were confined within the ventral margin of the principal subdivision. Taken together, the present observations demonstrate that each subdivision of the LC possesses a differential functional organization with respect to its collateral projection to whisker-related sensorimotor targets, suggesting that the nucleus might play a modulatory role in vibrissal sensorimotor integration that allows the guidance of behavioral action essential for the survival of the animal.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Dopamine beta-Hydroxylase / metabolism
  • Female
  • Gold Colloid
  • Immunohistochemistry
  • Locus Coeruleus / anatomy & histology*
  • Locus Coeruleus / metabolism
  • Male
  • Motor Cortex / anatomy & histology*
  • Neural Pathways / anatomy & histology
  • Neurons / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Somatosensory Cortex / anatomy & histology*
  • Thalamic Nuclei / anatomy & histology
  • Trigeminal Nuclei / anatomy & histology
  • Vibrissae*
  • Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate

Substances

  • Gold Colloid
  • Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
  • Dopamine beta-Hydroxylase