a large, composite cell group in the dorsomedial region of the thalamus having reciprocal connections with the entire extent of the frontal cortex anterior to the motor cortex (Brodmann area 4) and premotor cortex (Brodmann area 6). The afferent connections of the medial dorsal nucleus also include projections from the olfactory cortex and amygdala. Composed of a pars parvocellularis lateralis [TA] (lateral nucleus [TA] or parvocellular nucleus [TAalt]), a pars magnocellularis medialis [TA] (medial nucleus [TA] or magnocellular nucleus [TAalt]), and a pars paralaminaris [TA] (paralaminar part [TA] or pars laminaris [TAalt]). SYN: mediodorsal nucleus, nucleus medialis thalami, nucleus mediodorsalis.