The major signaling pathways flow through the hippocampus and combine to form a loop.
#Rat septum hippocampus anatomy plus#
Most anatomistsuse the term "hippocampus proper" to refer to the four CA fields, and hippocampal formationto refer to the hippocampus proper plus dentate gyrus and subiculum. After this comes a pair of ill-defined areas called the presubiculum and parasubiculum, then atransition to the cortex proper (mostly the entorhinal area of the cortex). After CA1 comes an area called the subiculum. The CA areas are all filled with densely packed Pyramidal cells similar to those found in the neocortex. Nextcome a series of Cornu Ammonis areas: first CA4 (which underlies the dentate gyrus), then CA3, thena very small zone called CA2, then CA1. The first of these, the dentate gyrus (DG), is actually a separatestructure, a tightly packed layer of small granule cells wrapped around the end of the hippocampus proper, forming a pointed wedge in some cross-sections, a semicircle in others. Starting at the dentate gyrus and working inward along the S-curve of the hippocampus means traversing aseries of narrow zones. While most neuroscientists no longer believe in the concept of a unified "limbic system", these regions are highly interconnected and do interact with one another. Paul MacLean once suggested, as part of his triune brain theory, that the limbic structures constitute the neural basis of emotion. These limbic structures include the hippocampus, cingulate cortex, olfactory cortex, and amygdala. The structures that line the edge of the hole collectively make up the so-called limbic system (Latin limbus = border), with the hippocampus lining the posterior edge of this hole. Topologically, the surface of a cerebral hemisphere can be regarded as a sphere with an indentation where it attaches to the midbrain. Neuroimaging pictures can show a number of different shapes, depending on the angle and location of the cut. Due to the three-dimensional curvature of this structure, two-dimensional sections such as shown are commonly seen. In primate brains, including humans, the portion of the hippocampus near the base of the temporal lobe is much broader than the part at the top. For example, in the rat, the two hippocampi look similar to a pair of bananas, joined at the stems.
#Rat septum hippocampus anatomy full#
This general layout holds across the full range of mammalian species, from hedgehog to human, although the details vary. It has a distinctive, curved shape that has been likened to the sea-horse monster of Greek mythology and the ram's horns of Amun in Egyptian mythology.
Hippocampus anatomy describes the physical aspects and properties of the hippocampus, a neural structure in the medial temporal lobe of the brain.