Libelle of note

The Diencephalon in its classic, columnar view was divided into four dorsoventrally arranged columns separated by ventricular sulci: the Epithalamus, the Dorsal thalamus, the Ventral thalamus and the Hypothalamus. Extensive embryological studies made it clear that the thalamic 'columns' are derived from transversely oriented zones, the Prosomeres (see TE). Currently, the (Caudal) Diencephalon is subdivided into three segmental units, which from caudal to rostral, contain in their alar domains the Pretectum (prosomere 1 or P1), the Epithalamus and the Thalamus (P2) and the Ventral thalamus or Prethalamus (P3). The diencephalic basal plate contains the rostral part of the Substantia nigra-VTA complex and some other nuclei, collectively forming the Diencephalic or Prerubral tegmentum between the Mesencephalon and the Hypothalamus. The entire Hypothalamus or Rostral diencephalon arises from the alar and basal components of the secondary prosencephalon. The Preoptic area is one of the subpallial developmental domains (Puelles L, Harrison M, Paxinos G, Watson C 2013 A developmental ontology for the mammalian brain based on the prosomeric model. Trends Neurosci 36:570-578).

Some new items have been added from ten Donkelaar HJ, Tzourio-Mazoyer N, Mai JK (2018) Toward a common terminology for the gyri and sulci of the human cerebral cortex. Front Neuroanat 12:93.

Under this Heading the structures presented in TA as Substantia basalis, Substantia innominata and Area septalis are grouped. Reichert's 'Substantia innominata' was for a long time a 'terra incognita' of the Basal forebrain. The extensive studies by Heimer and colleagues (Heimer L, Harlan RE, Alheid GF, et al. 1997 Substantia innominata: A notion which impedes clinico-anatomical correlations in neuropsychiatric disorders. Neuroscience 76:957-1006; Heimer et al. 1999; Sakamoto et al. 1999) make the term SI more or less superfluous.