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Perforant Path
In the brain, the perforant path or perforant pathway provides a connectional route from the entorhinal cortex to all fields of the hippocampal formation, including the dentate gyrus, all CA fields (including CA1), and the subiculum. Though it arises mainly from entorhinal layers II and III, the perforant path comprises a smaller component that originates in deep layers V and VI. There is a major dichotomy with respect to the laminar origin and related terminal distribution: neurons in layer II (and possibly layer VI) project to the dentate gyrus and CA3, whereas layer III (and possibly layer V) cells project to CA1 and the subiculum via the temporoammonic pathway. In addition to playing a role in spatial memory learning generally, the temporoammonic branch (TA-CA1) of the perforant path mediates spatial memory consolidation. The temporoammonic pathway has also been implicated in stress-based animal models of depression. It may also play a role in temporal lobe seizures. In r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hippocampal
The hippocampus (via Latin from Greek , 'seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, and plays important roles in the consolidation of information from short-term memory to long-term memory, and in spatial memory that enables navigation. The hippocampus is located in the allocortex, with neural projections into the neocortex in humans, as well as primates. The hippocampus, as the medial pallium, is a structure found in all vertebrates. In humans, it contains two main interlocking parts: the hippocampus proper (also called ''Ammon's horn''), and the dentate gyrus. In Alzheimer's disease (and other forms of dementia), the hippocampus is one of the first regions of the brain to suffer damage; short-term memory loss and disorientation are included among the early symptoms. Damage to the hippocampus can also result from oxygen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entorhinal Cortex
The entorhinal cortex (EC) is an area of the brain's allocortex, located in the medial temporal lobe, whose functions include being a widespread network hub for memory, navigation, and the perception of time.Integrating time from experience in the lateral entorhinal cortex Albert Tsao, Jørgen Sugar, Li Lu, Cheng Wang, James J. Knierim, May-Britt Moser & Edvard I. Moser Naturevolume 561, pages57–62 (2018) The EC is the main interface between the hippocampus and neocortex. The EC-hippocampus system plays an important role in declarative (autobiographical/episodic/semantic) memories and in particular spatial memories including memory formation, memory consolidation, and memory optimization in sleep. The EC is also responsible for the pre-processing (familiarity) of the input signals in the reflex nictitating membrane response of classical trace conditioning; the association of impulses from the eye and the ear occurs in the entorhinal cortex. Structure In rodents, the EC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hippocampal Formation
The hippocampal formation is a compound structure in the Temporal lobe#Medial temporal lobe, medial temporal lobe of the brain. It forms a c-shaped bulge on the floor of the temporal horn of the Lateral ventricles, lateral ventricle. There is no consensus concerning which brain regions are encompassed by the term, with some authors defining it as the dentate gyrus, the hippocampus proper and the subiculum; and others including also the Brodmann area 27, presubiculum, parasubiculum, and entorhinal cortex. The hippocampal formation is thought to play a role in memory, spatial navigation and control of attention. The neural layout and pathways within the hippocampal formation are very similar in all mammals. History and function During the nineteenth and early twentieth centuries, based largely on the observation that, between species, the size of the olfactory bulb varies with the size of the parahippocampal gyrus, the hippocampal formation was thought to be part of the olfactory sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dentate Gyrus
The dentate gyrus (DG) is part of the hippocampal formation in the temporal lobe of the brain, which also includes the hippocampus and the subiculum. The dentate gyrus is part of the hippocampal trisynaptic circuit and is thought to contribute to the formation of new episodic memories, the spontaneous exploration of novel environments and other functions. It is notable as being one of a select few brain structures known to have significant rates of adult neurogenesis in many species of mammals, from rodents to primates. Other sites of adult neurogenesis include the subventricular zone, the striatum and the cerebellum. However, whether significant neurogenesis exists in the adult human dentate gyrus has been a matter of debate. 2019 evidence has shown that adult neurogenesis does take place in the subventricular zone and in the subgranular zone of the dentate gyrus. Structure The dentate gyrus, like the hippocampus, consists of three distinct layers: an outer molecular layer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subiculum
The subiculum (Latin for "support") is the most inferior component of the hippocampal formation. It lies between the entorhinal cortex and the CA1 subfield of the hippocampus proper. The subicular complex comprises a set of related structures including (as well as subiculum proper) prosubiculum, presubiculum, postsubiculum and parasubiculum. Name The subiculum got its name from Karl Friedrich Burdach in his three-volume work ''Vom Bau und Leben des Gehirns'' (Vol. 2, §199). He originally named it subiculum cornu ammonis and so associated it with the rest of the hippocampal subfields. Structure It receives input from CA1 and entorhinal cortical layer III pyramidal neurons and is the main output of the hippocampus. The pyramidal neurons send projections to the nucleus accumbens, septal nuclei, prefrontal cortex, lateral hypothalamus, nucleus reuniens, mammillary nuclei, entorhinal cortex and amygdala. The pyramidal neurons in the subiculum exhibit transitions between two mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spatial Memory
In cognitive psychology and neuroscience, spatial memory is a form of memory responsible for the recording and recovery of information needed to plan a course to a location and to recall the location of an object or the occurrence of an event. Spatial memory is necessary for orientation in space. Spatial memory can also be divided into egocentric and allocentric spatial memory. A person's spatial memory is required to navigate around a familiar city. A rat's spatial memory is needed to learn the location of food at the end of a maze. In both humans and animals, spatial memories are summarized as a cognitive map. Spatial memory has representations within working, short-term memory and long-term memory. Research indicates that there are specific areas of the brain associated with spatial memory. Many methods are used for measuring spatial memory in children, adults, and animals. Short-term spatial memory Short-term memory (STM) can be described as a system allowing one to tempora ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Depression (mood)
Depression is a mental state of low mood and aversion to activity, which affects more than 280 million people of all ages (about 3.5% of the global population). Classified medically as a mental and behavioral disorder, the experience of depression affects a person's thoughts, behavior, motivation, feelings, and sense of well-being. The core symptom of depression is said to be anhedonia, which refers to loss of interest or a loss of feeling of pleasure in certain activities that usually bring joy to people. Depressed mood is a symptom of some mood disorders such as major depressive disorder and dysthymia; it is a normal temporary reaction to life events, such as the loss of a loved one; and it is also a symptom of some physical diseases and a side effect of some drugs and medical treatments. It may feature sadness, difficulty in thinking and concentration and a significant increase or decrease in appetite and time spent sleeping. People experiencing depression may have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temporal Lobe Seizure
Temporal lobe epilepsy (TLE) is a chronic disorder of the nervous system which is characterized by recurrent, unprovoked focal seizures that originate in the temporal lobe of the brain and last about one or two minutes. TLE is the most common form of epilepsy with focal seizures. A focal seizure in the temporal lobe may spread to other areas in the brain when it may become a ''focal to bilateral seizure''. TLE is diagnosed by taking a medical history, blood tests, and brain imaging. It can have a number of causes such as head injury, stroke, brain infections, structural lesions in the brain, brain tumors, or it can be of ''unknown onset''. The first line of treatment is through anticonvulsants. Surgery may be an option, especially when there is an observable abnormality in the brain. Another treatment option is electrical stimulation of the brain through an implanted device called the vagus nerve stimulator (VNS). Types Over forty types of epilepsy are recognized and these ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyramidal Cell
Pyramidal cells, or pyramidal neurons, are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cortex and the corticospinal tract. Pyramidal neurons are also one of two cell types where the characteristic sign, Negri bodies, are found in post-mortem rabies infection. Pyramidal neurons were first discovered and studied by Santiago Ramón y Cajal. Since then, studies on pyramidal neurons have focused on topics ranging from neuroplasticity to cognition. Structure File:GFPneuron.png, Pyramidal neuron visualized by green fluorescent protein (gfp) File:Hippocampal-pyramidal-cell.png, A hippocampal pyramidal cell One of the main structural features of the pyramidal neuron is the conic shaped soma, or cell body, after which the neuron is named. Other key structural features of the pyramidal cell are a single axon, a large apical dendrite, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellate Cell
Stellate cells are neurons in the central nervous system, named for their star-like shape formed by dendritic processes radiating from the cell body. Many stellate cells are GABAergic and are located in the molecular layer of the cerebellum. Stellate cells are derived from dividing progenitor cells in the white matter of postnatal cerebellum. Dendritic trees can vary between neurons. There are two types of dendritic trees in the cerebral cortex, which include pyramidal cells, which are pyramid shaped and stellate cells which are star shaped. Dendrites can also aid neuron classification. Dendrites with spines are classified as spiny, those without spines are classified as aspinous. Stellate cells can be spiny or aspinous, while pyramidal cells are always spiny. Most common stellate cells are the inhibitory interneurons found within the upper half of the molecular layer in the cerebellum. Cerebellar stellate cells synapse onto the dendritic trees of Purkinje cells and send inhibit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glutamate
Glutamic acid (symbol Glu or E; the ionic form is known as glutamate) is an α-amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a non-essential nutrient for humans, meaning that the human body can synthesize enough for its use. It is also the most abundant excitatory neurotransmitter in the vertebrate nervous system. It serves as the precursor for the synthesis of the inhibitory gamma-aminobutyric acid (GABA) in GABA-ergic neurons. Its molecular formula is . Glutamic acid exists in three optically isomeric forms; the dextrorotatory -form is usually obtained by hydrolysis of gluten or from the waste waters of beet-sugar manufacture or by fermentation.Webster's Third New International Dictionary of the English Language Unabridged, Third Edition, 1971. Its molecular structure could be idealized as HOOC−CH()−()2−COOH, with two carboxyl groups −COOH and one amino group −. However, in the solid state and mildly acidic water solu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enkephalin
An enkephalin is a pentapeptide involved in regulating nociception in the body. The enkephalins are termed endogenous ligands, as they are internally derived and bind to the body's opioid receptors. Discovered in 1975, two forms of enkephalin have been found, one containing leucine ("leu"), and the other containing methionine ("met"). Both are products of the proenkephalin gene. * Met-enkephalin is Tyr-Gly-Gly-Phe-Met. * Leu-enkephalin has Tyr-Gly-Gly-Phe-Leu. Endogenous opioid peptides There are three well-characterized families of opioid peptides produced by the body: enkephalins, B-endorphin, and dynorphins. The met-enkephalin peptide sequence is coded for by the enkephalin gene; the leu-enkephalin peptide sequence is coded for by both the enkephalin gene and the dynorphin gene. The proopiomelanocortin gene (POMC) also contains the met-enkephalin sequence on the N-terminus of beta-endorphin, but the endorphin peptide is not processed into enkephalin. Effects on stress ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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