Serotonergic fibers distribution in the midline and intralaminar thalamic nuclei in the rock cavy (Kerodon rupestris).

The thalamic midline/intralaminar complex is part of the higher-order thalamus, which receives little sensory input, and instead forms extensive cortico-thalamo-cortical pathways. The midline thalamic nuclei connect with the medial prefrontal cortex and the medial temporal lobe. On the other hand, the intralaminar nuclei connect with the fronto-parietal cortex.

Mediodorsal thalamic nucleus receives a direct retinal input in marmoset monkey (Callithrix jacchus): a subunit B cholera toxin study.

The mediodorsal thalamic nucleus is a prominent nucleus in the thalamus, positioned lateral to the midline nuclei and medial to the intralaminar thalamic complex in the dorsal thalamus. Several studies identify the mediodorsal thalamic nucleus as a key structure in learning and memory, as well as in emotional mechanisms and alertness due to reciprocal connections with the limbic system and prefrontal cortex. Fibers from the retina to the mediodorsal thalamic nucleus have recently been described for the first time in a crepuscular rodent, suggesting a possible regulation of the mediodorsal thalamic nucleus by visual activity.