Limbic and brainstem afferents to thalamic mediodorsal nucleus: a horseradish peroxidase study

Subcortical ipsilateral afferents to mediodorsal (MD) thalamic nucleus were investigated by retrograde transport of horseradish peroxidase (HRP). HRP was injected into the rostral and caudal part of MD following both a vertical and an oblique stereotaxic approach. We have identified MD afferents from the following structures: area septalis, amygdaloid complex, hypothalamus, mamillary bodies, tuberculum olfactorium, claustrum, ventral tegmental area, zona incerta, substantia nigra, griseum centralis, formatio reticularis mesencephali and pontis oralis. The projections from hypothalamus, amygdaloid nuclei and area septalis and reticular formation are in agreement with the integrative function of sensory afferents of this thalamic nucleus.