Septo-Hippocampo-Septal Loop and Memory Formation

Cholinergic and GABAergic fibers in the medial septal/diagonal band of Broca (MS/DB) area project to the hippocampus and constitute the septo-hippocampal pathway, which has been proven in learning and memory. In addition, the hippocampus has bidirectional connections with the septum, which use this relation for self-regulation of cholinergic input. The activity of septal and hippocampal neurons is modulated by several neurotransmitters including glutamatergic neurons from the entorhinal cortex, serotonergic fibers from the raphe nucleus, dopaminergic neurons from the ventral tegmental area (VTA), histaminergic cells from the tuberomammillary nucleus and adrenergic fibers from the locus coeruleus (LC). Thus, changes in the glutamatergic, serotonergic and etc. mediated transmission in the MS/DB may influence cholinergic or GABAergic transmission in the hippocampus.