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The hippocampal subfields are four subfields CA1, CA2, CA3, and CA4 that make up the structure of the hippocampus. Regions described in the hippocampus are the head, body, and tail, and other hippocampal subfields include the dentate gyrus , the presubiculum , and the subiculum .
The septal area refers to the nearby septum pellucidum. It is located underneath the corpus callosum and in front of the lamina terminalis. The lamina terminalis is a layer of gray matter that connects the optic chiasma and the anterior commissure. [7] The septal nuclei in the septal area are essential in generating the theta rhythm of the ...
The horned appearance of the hippocampus is caused by cell density differentials and varying degrees of neuronal fibers. In rodents, the hippocampus is positioned so that, roughly, one end is near the top of the head (the dorsal or septal end) and one end near the bottom of the head (the ventral or temporal end).
The hippocampus (pl.: hippocampi; via Latin from Greek ἱππόκαμπος, 'seahorse'), also hippocampus proper, is a major component of the brain of humans and many other vertebrates. In the human brain the hippocampus, the dentate gyrus, and the subiculum are the components of the hippocampal formation located in the limbic system.
The dentate gyrus (DG) is one of the subfields of the hippocampus, in the hippocampal formation. The hippocampal formation is located in the temporal lobe of the brain, and includes the hippocampus (including CA1 to CA4) subfields, and other subfields including the dentate gyrus, subiculum, and presubiculum. [1] [2]
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 inferior horn of the lateral ventricle . [ 1 ] Typically, the hippocampal formation is said to included the dentate gyrus , the hippocampus , and the subiculum . [ 2 ]
The fornix is the conduit by which the neurotransmitter acetylcholine – which is crucial for memory encoding – is sent from the medial septum/Diagonal band of Broca to the hippocampus. [7] In addition, the GABA-producing neurons in the septal nuclei generate theta rhythms which are transmitted through the fornix to the hippocampus.
For type 2 theta, the supramammillary nucleus of the hypothalamus appears to exert control . For type 1 theta, the picture is still unclear, but the most widely accepted hypothesis proposes that the frequency is determined by a feedback loop involving the medial septal area and hippocampus .