The medial septal nucleus (MS) is one of the

septal nuclei The septal area (medial olfactory area), consisting of the lateral septum and medial septum, is an area in the lower, posterior part of the medial surface of the frontal lobe, and refers to the nearby septum pellucidum. The septal nuclei are loca ...

. 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 The hippocampal formation is a compound structure in the medial temporal lobe of the brain. It forms a c-shaped bulge on the floor of the temporal horn of the lateral ventricle. There is no consensus concerning which brain regions are encompassed ...

. It plays a role in the generation of

theta wave Theta waves generate the theta rhythm, a neural oscillation in the brain that underlies various aspects of cognition and behavior, including learning, memory, and spatial navigation in many animals. It can be recorded using various electrophysi ...

s in the hippocampus. Specifically, the GABAergic cells of the medial septum that act as theta pacemakers target

dentate gyrus The dentate gyrus (DG) is part of the hippocampal formation in the temporal lobe of the brain, which also includes the hippocampus and the subiculum. The dentate gyrus is part of the hippocampal trisynaptic circuit and is thought to contribute t ...

, CA3, and CA1 interneurons. Pacemaking MS interneurons express hyperpolarization-activated cyclic nucleotide-gated (HCN) channels which likely, at least partially, mediate their pacemaker properties. It is composed of GABAergic cells, glutamatergic cells, and cholinergic cells. Each cell-type carries out different functions. In addition to the theta wave generation, it has recently been discovered that medial septum also serves as an important node for sensory valence processing. For example, Vglut2 neurons in medial septum respond strongly to noxious sensory stimulation.

References

Cerebrum {{Neuroanatomy-stub