The afferent and efferent connections of the ventromedial thalamic nucleus in the rat.

摘要: The afferent and efferent connections of the ventromedial (VM) nucleus thalamus in rat were studied by experiments using methods retrograde cell marking horseradish peroxidase (HRP) anterograde fiber tracing autoradiography. Tritiated amino acids deposited microelectrophoretically into VM label a cortical projection that is distributed to sharply defined superficial portion layer I almost entire extent ipsilateral neocortex. labeling most dense at frontal levels, where fibers radiate through deeper layers terminate outer one-quarter throughout all neocortex rostral genu corpus callosum. A lesser number labeled extends caudally supracallosal location innervate parieto-occipital areas. Labeled collaterals ascend reach I, grains are found gradually decreasing rostrocaudal gradient density reaches caudal pole hemisphere. Coronal sections levels contain band uninterrupted from callosal sulcus midline banks rhinal laterally. Caudal retrosplenial ventral temporal areas appear be only sectors spared ubiquitous projection. Evidence for additional terminal distribution dorsal lateral cortex sparsely bands III V. nearly exclusive VM's afferents compared contrasted with multilaminar distributions other “unspecific” fibers. HRP injected labels neurons variety structures ranging medulla. Cell labelling globus pallidus, deep superior colliculus, cerebellar nuclei substantia nigra, pars reticulata suggest point convergence several components extrapyramidal motor system. nigrothalamic topographic: medial districts connected VM, respectively. dorsal-ventral association may also obtain. prefrontal cortex, along sulcus, habenular nucleus, tegmental medullary reticular formations, parabrachial indicates receives projections more heterogeneous sources.