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May 14, 2024 · The hippocampus is a seahorse-shaped structure in your brain that helps with memory and learning. It's located in the temporal lobe, near your temples and ears. Learn about its function, anatomy, conditions and disorders, and how to care for it.
- Overview
- Anatomy of the hippocampus
- Principal neural circuits
- Morphological distinctions
- Sources of input
- Functions of the hippocampus
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hippocampus, region of the brain that is associated primarily with memory. The name hippocampus is derived from the Greek hippokampus (hippos, meaning “horse,” and kampos, meaning “sea monster”), since the structure’s shape resembles that of a sea horse. The hippocampus, which is located in the inner (medial) region of the temporal lobe, forms part...
The anatomy of the hippocampus is of chief importance to its function. The hippocampus receives input from and sends output to the rest of the brain via a structure known as the entorhinal cortex, which is located beneath the anterior (frontal) region of the hippocampus. The hippocampal formation itself is composed of several subregions, which incl...
The subregions of the hippocampus are connected by two principal neural circuits: the trisynaptic circuit and the monosynaptic circuit. The trisynaptic circuit forwards information from the entorhinal cortex to the dentate gyrus via the perforant path, which perforates through the subiculum. Information then flows from the dentate gyrus to CA3 via ...
The CA fields contain three layers (in contrast to the rest of the brain’s six-layered cortex) and use pyramidal cells (neurons with dendrites that spread to give the cell body a triangular appearance) as the principal excitatory cells. The CA3 region of the hippocampus contains a large excitatory recurrent collateral network (where axons loop back to input fibres, or dendrites), which constitutes the largest input source to CA3.
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The dentate gyrus is morphologically distinct from CA fields and contains densely packed granule cells (neurons with relatively small cell bodies). The dentate gyrus is also one of only two regions in the brain known to house neural stem cells that are capable of differentiating into new neurons throughout adulthood.
The hippocampus receives input from modulatory neurotransmitter systems, including serotonin, norepinephrine, and dopamine systems. It also receives cholinergic input (responds to the neurotransmitter acetylcholine) from the medial septum, which regulates the hippocampal physiological state. The medial septum is involved in setting one of the critical oscillatory rhythms in the hippocampus, the theta rhythm. Abolishing that region or the associated theta rhythm interferes with hippocampal function.
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The two most-influential theories for hippocampal function are related to space and memory. The spatial hypothesis was supported by the seminal discovery in 1971 of cells in the hippocampus that fired bursts of action potentials when a rat traversed specific locations in space, or “place fields.” That suggested that the hippocampus was a sort of device used by the brain for mapping layouts of the environment. Data supporting that idea came from later virtual navigation studies in humans, which suggested a strong association between the hippocampus and spatial navigation. The memory hypothesis originated in 1957 and was supported by studies and observations in which hippocampal removal resulted in a loss of the ability to form new memories, particularly fact- and event-related (declarative) memories.
Although there is near universal agreement among scientists that the hippocampus is important for memory, the exact processes by which the hippocampus supports memory are subject to much debate. Some studies suggest that the hippocampus binds items and contexts into unified experiences and stores them. Other studies suggest that the hippocampus is preferentially involved in conscious recollection, or the experience of mental time travel during recall. Still other studies suggest that the hippocampus is able to support rapid learning by reducing interference among similar memories (for example, where a person parked his or her car today versus yesterday). Some theories of hippocampal function treat the hippocampus as an index (much like an index at the end of a book) that binds together elements of an experience but does not store the experience itself. The latter is assumed to be stored in a distributed fashion throughout the brain, while the hippocampus is assumed to possess an index of that distributed code.
The hippocampus is a region of the brain associated with memory and spatial processing. It is located in the inner temporal lobe and forms part of the limbic system. Learn more about its anatomy, circuits, functions, and disorders.
Sep 19, 2023 · The hippocampus is a seahorse-shaped structure in the temporal lobe that plays a key role in memory, spatial navigation, and emotion. Learn about its anatomy, function, location, and how damage to it can affect learning and cognition.
Aug 12, 2022 · The hippocampus is a seahorse-shaped structure in the medial temporal lobe that is involved in learning and memory. It is part of the limbic system and the hippocampal formation, and has connections with the entorhinal cortex, amygdala, and fornix.
The hippocampus is a brain structure involved in memory and spatial navigation. It is part of the limbic system and has two main parts: the hippocampus proper and the dentate gyrus.
Oct 30, 2023 · Learn about the hippocampus, a paired structure in the temporal lobe of the brain, and its role in learning and memory. Find out its internal structure, layers, fields, connections, and clinical correlations.
Sep 1, 2022 · Learn about the hippocampus, a seahorse-shaped structure in the brain that stores and processes memories, emotions, and spatial skills. Find out where it is located, what it does, and what conditions can affect it.
