Journal ArticleDOI
Efferent connections of the periaqueductal gray matter in the cat.
TLDR
Electrolytic lesions were stereotaxically placed in the dorsal and ventral areas of the mesencephalic periaqueductal gray in the cat to avoid electrode damage.Abstract:
Electrolytic lesions were stereotaxically placed in the dorsal and ventral areas of the mesencephalic periaqueductal gray in the cat. A dorsal angular approach was made so that mechanical electrode damage was contralateral to the lesion, or a posterior approach through the fourth ventricle was employed to avoid electrode damage. The brains were sectioned coronally and sagittally and stained with a modifield Nauta-Gygax or Fink-Heimer stain.
Degeneration from the dorsal lesions was chiefly in a radial pattern to the superior colliculus, inferior colliculus and mesencephalic reticular area. Also, fibers angled out of the dorsal gray, crossed the midline and joined the commissure of the superior colliculus, some taking a ventrolateral course through the colliculi and others running ventrally along the borders of the gray. Degeneration was traced caudally to the cuneiform nucleus and adjacent reticular area. Rostrally, fibers traveled in the dorsal longitudinal fasciculus to the pretectal area, lateral habenular nucleus and finally, the posterior hypothalamic area.
Ventral lesions showed the same radial pattern of degeneration and fibers in the superior colliculus commissure. Caudally, fibers could be traced to the cuneiform nucleus, reticular area and inferior olive. The rostral course of fibers in the dorsal longitudinal fasciculus was similar, though there were additional connections with the ventral tegmental area of Tsai, the fields of Forel, and the parafascicular nucleus of the thalamus.read more
Citations
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Journal ArticleDOI
Vestibulospinal and reticulospinal interactions in the activation of back muscle EMG in the rat.
TL;DR: Results of stimulation at 200–330 Hz to RF or LVN showed that muscle units were activated at a fixed latency from any effective pulse in the stimulus train, consistent with monosynaptic activation.
Journal ArticleDOI
The benefits of magnetic resonance imaging methods to extend the knowledge of the anatomical organisation of the periaqueductal gray in mammals.
TL;DR: The MRI seems to be the best judicious method to compare species and improve the comprehension of the role of the PAG, and results obtained by MRI so far support the conclusions of ex vivo studies.
Journal ArticleDOI
Cortically projecting cells in the periaqueductal gray matter of the rat. A retrograde fluorescent tracer study
TL;DR: The data indicate that the medial frontal cortex is the most important recipient of a direct PAG input, followed by the lateral frontal cortex, and it is concluded that the PAG sends direct projections over the majority of the cortical mantle.
Journal ArticleDOI
Cerebellar cortical afferents from the periaqueductal grey in the cat.
TL;DR: A cerebellar afferent connection from the periaqueductal grey has been demonstrated in the cat by means of retrograde transport of the wheat germ agglutinin-horseradish peroxidase complex.
Journal ArticleDOI
Electrical stimulation of the midbrain central gray facilitates lateral vestibulospinal activation of back muscle EMG in the rat
TL;DR: Results are consistent with participation of these neuronal groups in the activation of lordosis behavior, a vertebral dorsiflexion that requires deep back muscle contraction, but these electromyographic results could also be relevant for other behaviors that require vertebral postural adjustments.
References
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Journal ArticleDOI
Two methods for selective silver impregnation of degenerating axons and their synaptic endings in the central nervous system.
Robert P. Fink,Lennart Heimer +1 more
TL;DR: The original, non-suppressive Natua method for impregenation of terminal degeneration has been modified by the introduction of a potassium permanganate-uranyl nitrate sequence, resulting in a selective impregnation of degenarated axons inclusive of their synaptic thickenings.
Book
The brain stem of the cat : a cytoarchitectonic atlas with stereotaxic coordinates
TL;DR: This slim (73 text pages) volume stresses the "integrating functions of the vagi" in discussing vagal influences on the cardiovascular, respiratory, and gastrointestinal systems.
Journal ArticleDOI
Hippocampal projections and related neural pathways to the mid-brain in the cat
TL;DR: Recent studies in the rat have confirmed much earlier descriptions of widespread distributions of the fornix system to the diencephalon and the rostral mid-brain regions.
Journal ArticleDOI
Ascending axon degeneration following anterolateral cordotomy. An experimental study in the monkey.
TL;DR: In the same year in which Gowers wrote the prophetic statement quoted above, Bechterew on the basis of mylogenetic studies described two ascending fibre systems in the anterolateral funiculus of the spinal cord, two systems that were directly continuous into the reticular formation of the brain-stem.