The midline cores - nucl. paraventricularis, nucl. paratenialis and nucl. Reuniens - is counted to the group of nonspecific thalamus nuclei.

The midline nuclei consist of difficult-to-define thin streaks of neurons located in the thalamus wall towards the third ventricle. Do not confuse the nucleus paraventricularis of the thalamus with the important hormone-producing (vasopressin and oxytocin) nucleus paraventricularis of the hypothalamus.

The mean line nuclei of the visual pile receive signals primarily from formatio reticularis, including PAGs, locus coeruleus and nucleus raphes dorsalis, as well as from scattered areas of the reticular thalamus nucleus.

The midline nuclei transmit signals to the striatum, nucleus accumbens and amygdala. They have round-trip connections with the dentate cingulis anterior, prefrontal cortex and entorhinal cortex as well as more diffuse with the entire cortex.

Functionally, the mean line nuclei are also considered to be involved in the intestinal influence of the limbic system and are included in the group of limbic thalamus nuclei.

Nucl. Reuniens is most likely a switching station involved in memory activation from the prefrontal cortex to the hippocampus. The nucleus appears to be of particular importance for memories linked to post-traumatic stress release.
Xu, W. and Südhof, T. C (2013). A Neural Circuit for Memory Specificity and Generalization. Science,339. 1290-1295.