Elsevier

Neuroscience

Volume 9, Issue 1, May 1983, Pages 41-52
Neuroscience

Anatomical and electrophysiological studies on the reciprocal projections between the subthalamic nucleus and nucleus tegmenti pedunculopontinus in the rat

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Abstract

Reciprocal projections between the subthalamic nucleus of the diencephalon and the brain stem nucleus tegmenti pedunculopontinus have been demonstrated and studied anatomically and electrophysiologically in the rat. Injections of the fluorescent compound Fast Blue into pedunculopontinus and the surrounding peribrachial region of the mesencephalon gave rise to retrogradelylabelled neurone cell bodies in the ipsilateral subthalamic nucleus. A minimum of 1% of subthalamic nucleus neurones appeared to contribute to this projection. Electrical stimulation of the subthalamic nucleus in chronically decorticated rats resulted in inhibition of extracellularly recorded ipsilateral pedunculopontine cells which had themselves been identified (by antidromic activation) as projecting rostrally as far as the subthalamic nucleus or entopeduncular nucleus. Injection of the enzyme horseradish peroxidase into the subthalamic nucleus resulted in retrograde labelling of neurones in the ipsilateral nucleus tegmenti pedunculopontinus with additional contralateral labelling in some animals. Similar pedunculopontine labelling was not seen after injection of horseradish peroxidase into either the zona incerta or lateral hypothalamus. Stimulation of the subthalamic nucleus gave rise to antidromic activation of some neurones in nucleus tegmenti pedunculopontinus. The rate of conduction of the pedunculopontine-subthalamic projection was estimated to be approximately 1.7 m/s. Electrical stimulation of pedunculopontinus gave rise to orthodromic activation of some subthalamic nucleus neurones which had themselves been identified (by antidromic activation) as projecting to the globus pallidus or substantia nigra.

The nucleus tegmenti pedunculopontinus is in a position to fulfill two roles—to control the activity of rostrally-located motor centres such as the globus pallidus, entopeduncular nucleus, subthalamic nucleus and substantia nigra and, by reciprocal connections, to mediate in part the effects of these structures on the lower motor system. The observations presently described are a first step in the analysis of the potential role of the pedunculopontine nucleus in the modulation of activity in, and the mediation of activity from, the basal ganglia and related motor structures of the diencephalon and mesencephalon.

Reference (31)

  • RicardoJ.A.

    Efferent connections of the subthalamic region in the rat—II. The zona incerta

    Brain Res.

    (1981)
  • Albe-FessardD. et al.

    Atlas Stéréotaxique du Rat Blanc

    (1966)
  • CarpenterM.B. et al.

    Analysis of somatotopic relations of the corpus Luysi in man and monkey

    J. comp. Neurol.

    (1951)
  • CrossmanA.R. et al.

    Studies on site specificity of intracerebral drug injection in the production of experimental hemiballismus in the monkey

    J. Physiol., Lond.

    (1981)
  • GraybielA.M.

    Direct and indirect preoculomotor pathways of the brainstem: an autoradiographic study of the pontine reticular formation in cat

    J. comp. Neurol.

    (1977)
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