[citation needed] This is a cholinergic bundle of nerve fibers posterior to the anterior perforated substance.

[citation needed] Two structures are often described in this brain regions, namely the nuclei of the vertical and horizontal limbs of the diagonal band of Broca (nvlDBB and nhlDBB, respectively).

nvlDBB projects to the hippocampal formation through the fornix and it is the second largest assembly of cholinergic neurons in the basal forebrain whereas nhlDBB projects to the olfactory bulb and it does not have a significant population of cholinergic neurons.

[2] Along with the septum pellucidum and medial septal nucleus, the diagonal band of Broca is believed to be involved in the generation of theta waves in the hippocampus.

[3] This article incorporates text in the public domain from page 868 of the 20th edition of Gray's Anatomy (1918)