Magnocellular Division Of Ventral Anterior Nucleus Of Thalamus


CM also had substantial input from multisensory nuclei, especially the magnocellular division (MGm) of the MGC.  

The pars oralis division of VL projects primarily to the dorsolateral, postcommissural putamen, whereas the parvicellular VA targets more medial and rostral putamen regions, and the magnocellular division of VA targets the dorsal head of the caudate nucleus.  

Moderate numbers of these fibers were found in the olfactory bulb, insular, infralimbic and prelimbic cortex, amygdala, ventral, and dorsolateral parts of the suprachiasmatic nucleus, paraventricular nucleus except the lateral magnocellular division, arcuate nucleus, supramammillary nucleus, nucleus of the solitary tract, and dorsal motor nucleus of the vagus. Small numbers of orexin fibers were present in the perirhinal, motor and sensory cortex, hippocampus, and supraoptic nucleus, and a very small number in the lateral magnocellular division of the paraventricular nucleus. Intracerebroventricular injections of orexins induced c-fos expression in the paraventricular thalamic nucleus, locus coeruleus, arcuate nucleus, central gray, raphe nuclei, nucleus of the solitary tract, dorsal motor nucleus of the vagus, suprachiasmatic nucleus, supraoptic nucleus, and paraventricular nucleus except the lateral magnocellular division.  

The results indicated that ventral precallosal and subcallosal areas 14 and 25, and the ventral, subcallosal part of area 32, all receive projections from the mediodorsal portion of the magnocellular division of the medial dorsal nucleus (MDmc).  

The first two of these represent a parcellation of the magnocellular division into a lateral, fiber-rich MD pars fibrosa and a medial, poorly myelinated MD pars paramediana adjacent to the midline.  

Projections to the magnocellular division of the PVH and the SO were generally sparse and inconsistently observed in this material.  

The anterior nuclei are highly differentiated because both the dorsal and ventral nuclei have parvicellular and magnocellular divisions. The lateral nuclei and the parvicellular and magnocellular divisions of the anterior dorsal nucleus project with progressively higher densities in the rostrocaudal plane of area 29. Finally, the magnocellular division of the anterior ventral nucleus projects almost exclusively to caudal and ventral area 29, i.e., granular retrosplenial cortex. The binding of Tyr-D-Ala-Gly-MePhe-Gly-ol to mu opioid receptors and 2-D-penicillamine-5-D-penicillamine-enkephalin to delta opioid receptors were both high in the parvicellular and low in the magnocellular divisions of the anterior dorsal nucleus. The magnocellular division of the anterior ventral, the lateral dorsal, and the parafascicular nuclei had high mu opioid binding, while the lateral dorsal and lateral magnocellular nuclei had low levels of delta opioid binding.(ABSTRACT TRUNCATED AT 400 WORDS).  

In the parvicellular division of the PVH, the most prominent inputs were confined to the anterior and periventricular parts of the nucleus rostrally and the dorsal and ventral medial subdivisions caudally; the galaninergic inputs to the magnocellular division of PVH and SO were very sparse and were preferentially distributed to regions containing predominantly oxytocinergic neurons.  

ACTH immunostained fibers were present in the anterior and medial magnocellular component of PVN and in the ventral medial portion of the posterior magnocellular division; these immunoreactive fibers were in intimate proximity to oxytocin-ir perikarya. Few ACTH immunostained fibers were seen in the dorsal lateral portion of the posterior magnocellular division in which vasopressinergic neurons predominate.  

Projections from the posterior thalamic regions to the striatum were studied in the cat by the anterograde tracing method after injecting wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) into the caudalmost regions of the lateroposterior thalamic nucleus (caudal LP), suprageniculate nucleus (Sg) and magnocellular division of the medial geniculate nucleus (MGm).  

Consistent numbers of labeled neurons were also identified in the lateral medial subdivision of the lateral posterior-pulvinar complex, suprageniculate nucleus, posterior thalamic nuclear group and magnocellular division of the medial geniculate nucleus.  

The most prominent projection arises from the ventromedial nucleus of the hypothalamus and terminates most heavily in the medial, magnocellular division of the central nucleus.  

The fact that the projection reached the most lateral and ventral extent of MD abutting the intralaminar complex suggests that the entire opossum MD may correspond to only the medial, magnocellular division in the primate and that the equivalents of both the parvocellular and paralamellar divisions may be absent..  

Areas PLLS and ALLS were both found to project retinotopically upon the interjacent zone of the lateral posterior complex, as well as to the intermediate and suprageniculate divisions of the posterior nuclear group, the magnocellular division of the medial geniculate complex, the thalamic reticular complex, and central lateral nucleus.  

Such targets include the visceral cell columns of the oculomotor complex, the rostral interstitial nucleus of the medial longitudinal fasciculus, and the magnocellular division of the ventral anterior nucleus.  

These units, preferentially excited from contralateral receptive fields, were localized in POm, POl, suprageniculate nuclei, the magnocellular division of the medial geniculate body (Mgmc) and the ventral part of the lateral posterior nucleus.  


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