Medial septal nucleus
The medial septal nucleus 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 role in the generation of theta waves in the hippocampus. Specifically, the GABAergic cells of the medial septum that act as theta pacemakers target dentate gyrus, CA3, and CA1 interneurons. Pacemaking MS interneurons express hyperpolarization-activated cyclic nucleotide-gated channels which likely, at least partially, mediate their pacemaker properties.