Related Research Articles
A dendrite or dendron is a branched protoplasmic extension of a nerve cell that propagates the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites project. Electrical stimulation is transmitted onto dendrites by upstream neurons via synapses which are located at various points throughout the dendritic tree.
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of the allocortex. It is separated into two cortices, by the longitudinal fissure that divides the cerebrum into the left and right cerebral hemispheres. The two hemispheres are joined beneath the cortex by the corpus callosum. The cerebral cortex is the largest site of neural integration in the central nervous system. It plays a key role in attention, perception, awareness, thought, memory, language, and consciousness. The cerebral cortex is part of the brain responsible for cognition.
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 cells 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.
Basket cells are inhibitory GABAergic interneurons of the brain, found throughout different regions of the cortex and cerebellum.
An apical dendrite is a dendrite that emerges from the apex of a pyramidal cell. Apical dendrites are one of two primary categories of dendrites, and they distinguish the pyramidal cells from spiny stellate cells in the cortices. Pyramidal cells are found in the prefrontal cortex, the hippocampus, the entorhinal cortex, the olfactory cortex, and other areas. Dendrite arbors formed by apical dendrites are the means by which synaptic inputs into a cell are integrated. The apical dendrites in these regions contribute significantly to memory, learning, and sensory associations by modulating the excitatory and inhibitory signals received by the pyramidal cells.
A basal dendrite is a dendrite that emerges from the base of a pyramidal cell that receives information from nearby neurons and passes it to the soma, or cell body. Due to their direct attachment to the cell body itself, basal dendrites are able to deliver strong depolarizing currents and therefore have a strong effect on action potential output in neurons. The physical characteristics of basal dendrites vary based on their location and species that they are found in. For example, the basal dendrites of humans are overall found to be the most intricate and spine-dense, as compared to other species such as Macaques. It is also observed that basal dendrites of the prefrontal cortex are larger and more complex in comparison to the smaller and simpler dendrites that can be seen within the visual cortex. Basal dendrites are capable of vast amounts of analog computing, which is responsible for many of the different nonlinear responses of modulating information in the neocortex. Basal dendrites additionally exist in dentate granule cells for a limited time before removal via regulatory factors. This removal usually occurs before the cell reaches adulthood, and is thought to be regulated through both intracellular and extracellular signals. Basal dendrites are part of the more overarching dendritic tree present on pyramidal neurons. They, along with apical dendrites, make up the part of the neuron that receives most of the electrical signaling. Basal dendrites have been found to be involved mostly in neocortical information processing.
Betz cells are giant pyramidal cells (neurons) located within the fifth layer of the grey matter in the primary motor cortex. These neurons are the largest in the central nervous system, sometimes reaching 100 μm in diameter.
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 inhibitory signals. Stellate neurons are sometimes found in other locations in the central nervous system; cortical spiny stellate cells are found in layer IVC of the primary visual cortex. In the somatosensory barrel cortex of mice and rats, glutamatergic (excitatory) spiny stellate cells are organized in the barrels of layer 4. They receive excitatory synaptic fibres from the thalamus and process feed forward excitation to 2/3 layer of the primary visual cortex to pyramidal cells. Cortical spiny stellate cells have a 'regular' firing pattern. Stellate cells are chromophobes, that is cells that does not stain readily, and thus appears relatively pale under the microscope.
In neuroscience, Golgi cells are the most abundant inhibitory interneurons found within the granular layer of the cerebellum. Golgi cells can be found in the granular layer at various layers. The Golgi cell is essential for controlling the activity of the granular layer. They were first identified as inhibitory in 1964. It was also the first example of an inhibitory feedback network in which the inhibitory interneuron was identified anatomically. Golgi cells produce a wide lateral inhibition that reaches beyond the afferent synaptic field and inhibit granule cells via feedforward and feedback inhibitory loops. These cells synapse onto the dendrite of granule cells and unipolar brush cells. They receive excitatory input from mossy fibres, also synapsing on granule cells, and parallel fibers, which are long granule cell axons. Thereby this circuitry allows for feed-forward and feed-back inhibition of granule cells.
Retinotopy is the mapping of visual input from the retina to neurons, particularly those neurons within the visual stream. For clarity, 'retinotopy' can be replaced with 'retinal mapping', and 'retinotopic' with 'retinally mapped'.
Chandelier neurons or chandelier cells are a subset of GABAergic cortical interneurons. They are described as parvalbumin-containing and fast-spiking to distinguish them from other subtypes of GABAergic neurons, although more recent work has suggested that only a subset of chandelier cells test positive for parvalbumin by immunostaining. The name comes from the specific shape of their axon arbors, with the terminals forming distinct arrays called "cartridges". The cartridges are immunoreactive to an isoform of the GABA membrane transporter, GAT-1, and this serves as their identifying feature. GAT-1 is involved in the process of GABA reuptake into nerve terminals, thus helping to terminate its synaptic activity. Chandelier neurons synapse exclusively to the axon initial segment of pyramidal neurons, near the site where action potential is generated. It is believed that they provide inhibitory input to the pyramidal neurons, but there is data showing that in some circumstances the GABA from chandelier neurons could be excitatory.
Recurrent thalamo-cortical resonance is an observed phenomenon of oscillatory neural activity between the thalamus and various cortical regions of the brain. It is proposed by Rodolfo Llinas and others as a theory for the integration of sensory information into the whole of perception in the brain. Thalamocortical oscillation is proposed to be a mechanism of synchronization between different cortical regions of the brain, a process known as temporal binding. This is possible through the existence of thalamocortical networks, groupings of thalamic and cortical cells that exhibit oscillatory properties.
Hippocampus anatomy describes the physical aspects and properties of the hippocampus, a neural structure in the medial temporal lobe of the brain. 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. This general layout holds across the full range of mammalian species, from hedgehog to human, although the details vary. For example, in the rat, the two hippocampi look similar to a pair of bananas, joined at the stems. 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. Due to the three-dimensional curvature of this structure, two-dimensional sections such as shown are commonly seen. Neuroimaging pictures can show a number of different shapes, depending on the angle and location of the cut.
The anatomy of the cerebellum can be viewed at three levels. At the level of gross anatomy, the cerebellum consists of a tightly folded and crumpled layer of cortex, with white matter underneath, several deep nuclei embedded in the white matter, and a fluid-filled ventricle in the middle. At the intermediate level, the cerebellum and its auxiliary structures can be broken down into several hundred or thousand independently functioning modules or compartments known as microzones. At the microscopic level, each module consists of the same small set of neuronal elements, laid out with a highly stereotyped geometry.
The name granule cell has been used for a number of different types of neurons whose only common feature is that they all have very small cell bodies. Granule cells are found within the granular layer of the cerebellum, the dentate gyrus of the hippocampus, the superficial layer of the dorsal cochlear nucleus, the olfactory bulb, and the cerebral cortex.
The development of the cerebral cortex, known as corticogenesis is the process during which the cerebral cortex of the brain is formed as part of the development of the nervous system of mammals including its development in humans. The cortex is the outer layer of the brain and is composed of up to six layers. Neurons formed in the ventricular zone migrate to their final locations in one of the six layers of the cortex. The process occurs from embryonic day 10 to 17 in mice and between gestational weeks seven to 18 in humans.
Cajal–Retzius cells are a heterogeneous population of morphologically and molecularly distinct reelin-producing cell types in the marginal zone/layer I of the developmental cerebral cortex and in the immature hippocampus of different species and at different times during embryogenesis and postnatal life.
Rosehip neurons are inhibitory GABAergic neurons present in the first layer of the human cerebral cortex. They make up about 10-15% of all inhibitory neurons in Layer 1. Neurons of this type exist in humans, but have not been reported in rodents.
Neurogliaform cells (NGF) are inhibitory (GABAergic) interneurons found in the cortex and the hippocampus. NGF cells represent approximately 10% of the total hippocampal inhibitory interneuron population.
Brain cells make up the functional tissue of the brain. The rest of the brain tissue is structural or connective called the stroma which includes blood vessels. The two main types of cells in the brain are neurons, also known as nerve cells, and glial cells, also known as neuroglia.
References
- ↑ Wang Y, Toledo-Rodriguez M, Gupta A, et al. (November 2004). "Anatomical, physiological and molecular properties of Martinotti cells in the somatosensory cortex of the juvenile rat". J. Physiol. 561 (Pt 1): 65–90. doi:10.1113/jphysiol.2004.073353. PMC 1665344 . PMID 15331670.
- ↑ Sugino K, Hempel CM, Miller MN, et al. (January 2006). "Molecular taxonomy of major neuronal classes in the adult mouse forebrain". Nat. Neurosci. 9 (1): 99–107. doi:10.1038/nn1618. PMID 16369481. S2CID 27815855.
- ↑ Hilscher, Markus M.; Leão, Richardson N.; Edwards, Steven J.; Leão, Katarina E.; Kullander, Klas (2017-02-09). "Chrna2-Martinotti Cells Synchronize Layer 5 Type A Pyramidal Cells via Rebound Excitation". PLOS Biology. 15 (2): e2001392. doi: 10.1371/journal.pbio.2001392 . ISSN 1545-7885. PMC 5300109 . PMID 28182735.
- ↑ Riedemann, T (17 June 2019). "Diversity and Function of Somatostatin-Expressing Interneurons in the Cerebral Cortex". International Journal of Molecular Sciences. 20 (12): 2952. doi: 10.3390/ijms20122952 . PMC 6627222 . PMID 31212931.
- ↑ Silberberg G, Markram H (March 2007). "Disynaptic inhibition between neocortical pyramidal cells mediated by Martinotti cells". Neuron. 53 (5): 735–46. doi: 10.1016/j.neuron.2007.02.012 . PMID 17329212. S2CID 15624023.
- ↑ Martinotti C (1889). "Contributo allo studio della corteccia cerebrale, ed all'origine centrale dei nervi". Ann. Freniatr. Sci. Affini. 1: 14–381.
 | This neuroanatomy article is a stub. You can help Wikipedia by expanding it. |