The diagonal band of Broca is one of the basal forebrain structures that are derived from the ventral telencephalon during development. This structure forms the medial margin of the

anterior perforated substance The anterior perforated substance is a part of the brain. It is bilateral. It is irregular and quadrilateral. It lies in front of the optic tract and behind the olfactory trigone. Structure The anterior perforated substance is bilateral. It ...

. This brain region was described by the French neuroanatomist Paul Broca.

Structure

It consists of fibers that are said to arise in the parolfactory area, the gyrus subcallosus and the

, and course backward in the

longitudinal striae In human neuroanatomy, the longitudinal striae (also striae lancisi or nerves of Lancisi) are two bundles of fibres embedded in the indusium griseum running along the corpus callosum of the brain. They were originally described by Italian physicia ...

to the dentate gyrus and the

hippocampal region The hippocampus (via Latin from Greek , 'seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, an ...

. This is a cholinergic bundle of nerve fibers posterior to the

. It interconnects the subcallosal gyrus in the septal area with the hippocampus and

lateral olfactory area Lateral is a geometric term of location which may refer to: Healthcare * Lateral (anatomy), an anatomical direction *Lateral cricoarytenoid muscle *Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...

Nuclei

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 Fornix (plural ''fornices'', Latin for "arch") can refer to: *''Fornix'' or ''throat scale'', a bowed prolongation of the corolla Corolla may refer to: *Corolla (botany), the petals of a flower, considered as a unit *Toyota Corolla, an automobile ...

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.

Function

Along with the septum pellucidum and

medial septal nucleus The medial septal nucleus (MS) is one of the septal nuclei. Neurons in this nucleus give rise to the bulk of efferents from the septal nuclei. A major projection from the medial septal nucleus terminates in the hippocampal formation. It plays a ro ...

, the diagonal band of Broca is believed to be involved in the generation of theta waves in the hippocampus. It also inhibits

magnocellular neurosecretory cell Magnocellular neurosecretory cells are large neuroendocrine cells within the supraoptic nucleus and paraventricular nucleus of the hypothalamus. They are also found in smaller numbers in accessory cell groups between these two nuclei, the largest ...

s via GABA interneurons. Its behavior can be altered by

nerve growth factor Nerve growth factor (NGF) is a neurotrophic factor and neuropeptide primarily involved in the regulation of growth, maintenance, proliferation, and survival of certain target neurons. It is perhaps the prototypical growth factor, in that it was on ...

Pathology

A significant nvlDBB neuronal loss is seen in Lewy body dementia.

References

{{Authority control Rostral basal ganglia and associated structures