Schematic of the Radial Unit Hypothesis as related to the Protomap Hypothesis (colored regions) of cortical development and evolution. Adapted from Rakic, 1995, 2009. VZ, ventricular zone; SVZ, subventricular zone; IZ, intermediate zone; SP, subplate; CP, cortical plate; MZ, marginal zone; RG, radial glia; MN, migrating neuron; TR, thalamic radiation; CC, cortico-cortical axons. E## represents post-conceptional age of macaque monkey.
The reiterative nature of the cerebral cortex, in the sense that it is a vast array of repeating functional circuits, led to the idea that cortical evolution is governed by mechanisms regulating the addition of cortical columns, enabling additional functional areas to become specialized and incorporated into the brain. The addition of new radial units is thought to depend on control of the cell cycle (proliferation) of cortical stem cells lining the ventricular system in the ventricular zone and subventricular zone.[3]
Protomapedit
Intimately related to the RUH is the 'protomap' hypothesis, which states that the primordial identity of each functional area of the cerebral cortex is encoded within the cortical stem cells prior to the formation of the cortical layers.[1] Within each developing radial unit, the process of neurogenesis gives rise to post-mitotic (non-dividing) cortical neurons, which begin the process of radial neuronal migration from the ventricular zone and adjacent subventricular zone to form the cortical plate in the classic 'inside-out' manner beginning with the deep cortical layers.[4][5] Once their final destination is achieved, cortical neurons begin to form circuits with other cortical and subcortical neurons, often taking on a columnar shape following the radial migration route.[6] Some localized lateral dispersion takes place during cortical column development in the mouse, but the degree of dispersion is molecularly regulated and indeed could vary across species.[7]
Principles of developmentedit
Together, the RUH and protomap hypothesis represent two core principles of early cerebral cortex development.[3] After neurons arrive in the cortical plate, other processes—especially activity-dependent processes—govern the maturation of cortical circuitry.[8]
^ abRakic, P (8 July 1988). "Specification of cerebral cortical areas". Science. 241 (4862): 170–6. doi:10.1126/science.3291116. PMID 3291116.
^Rakic, P (September 1995). "A small step for the cell, a giant leap for mankind: a hypothesis of neocortical expansion during evolution". Trends in Neurosciences. 18 (9): 383–8. doi:10.1016/0166-2236(95)93934-p. PMID 7482803. S2CID 11913076.
^ abRakic, P (October 2009). "Evolution of the neocortex: a perspective from developmental biology". Nature Reviews. Neuroscience. 10 (10): 724–35. doi:10.1038/nrn2719. PMC2913577. PMID 19763105.
^Rakic, P (May 1972). "Mode of cell migration to the superficial layers of fetal monkey neocortex". The Journal of Comparative Neurology. 145 (1): 61–83. doi:10.1002/cne.901450105. PMID 4624784. S2CID 41001390.
^Rakic, P (1 February 1974). "Neurons in rhesus monkey visual cortex: systematic relation between time of origin and eventual disposition". Science. 183 (4123): 425–7. doi:10.1126/science.183.4123.425. PMID 4203022. S2CID 10881759.
^Torii, M; Hashimoto-Torii, K; Levitt, P; Rakic, P (24 September 2009). "Integration of neuronal clones in the radial cortical columns by EphA and ephrin-A signalling". Nature. 461 (7263): 524–8. doi:10.1038/nature08362. PMC2874978. PMID 19759535.
^Ackman, JB; Burbridge, TJ; Crair, MC (11 October 2012). "Retinal waves coordinate patterned activity throughout the developing visual system". Nature. 490 (7419): 219–25. doi:10.1038/nature11529. PMC3962269. PMID 23060192.
April 10, 2024
radial, unit, hypothesis, this, article, technical, most, readers, understand, please, help, improve, make, understandable, experts, without, removing, technical, details, february, 2017, learn, when, remove, this, template, message, radial, unit, hypothesis, . This article may be too technical for most readers to understand Please help improve it to make it understandable to non experts without removing the technical details February 2017 Learn how and when to remove this template message The Radial Unit Hypothesis RUH is a conceptual theory of cerebral cortex development first described by Pasko Rakic The RUH states that the cerebral cortex develops during embryogenesis as an array of interacting cortical columns or radial units each of which originates from a transient stem cell layer called the ventricular zone which contains neural stem cells known as radial glial cells 1 2 Schematic of the Radial Unit Hypothesis as related to the Protomap Hypothesis colored regions of cortical development and evolution Adapted from Rakic 1995 2009 VZ ventricular zone SVZ subventricular zone IZ intermediate zone SP subplate CP cortical plate MZ marginal zone RG radial glia MN migrating neuron TR thalamic radiation CC cortico cortical axons E represents post conceptional age of macaque monkey Contents 1 Cortical evolution 2 Protomap 3 Principles of development 4 See also 5 ReferencesCortical evolution editThe reiterative nature of the cerebral cortex in the sense that it is a vast array of repeating functional circuits led to the idea that cortical evolution is governed by mechanisms regulating the addition of cortical columns enabling additional functional areas to become specialized and incorporated into the brain The addition of new radial units is thought to depend on control of the cell cycle proliferation of cortical stem cells lining the ventricular system in the ventricular zone and subventricular zone 3 Protomap editIntimately related to the RUH is the protomap hypothesis which states that the primordial identity of each functional area of the cerebral cortex is encoded within the cortical stem cells prior to the formation of the cortical layers 1 Within each developing radial unit the process of neurogenesis gives rise to post mitotic non dividing cortical neurons which begin the process of radial neuronal migration from the ventricular zone and adjacent subventricular zone to form the cortical plate in the classic inside out manner beginning with the deep cortical layers 4 5 Once their final destination is achieved cortical neurons begin to form circuits with other cortical and subcortical neurons often taking on a columnar shape following the radial migration route 6 Some localized lateral dispersion takes place during cortical column development in the mouse but the degree of dispersion is molecularly regulated and indeed could vary across species 7 Principles of development editTogether the RUH and protomap hypothesis represent two core principles of early cerebral cortex development 3 After neurons arrive in the cortical plate other processes especially activity dependent processes govern the maturation of cortical circuitry 8 See also editNeural stem cell Stem cell Ventricular zone Subventricular zone Neurogenesis Cellular differentiation Cortical patterning Protomap Cortical columnReferences edit a b Rakic P 8 July 1988 Specification of cerebral cortical areas Science 241 4862 170 6 doi 10 1126 science 3291116 PMID 3291116 Rakic P September 1995 A small step for the cell a giant leap for mankind a hypothesis of neocortical expansion during evolution Trends in Neurosciences 18 9 383 8 doi 10 1016 0166 2236 95 93934 p PMID 7482803 S2CID 11913076 a b Rakic P October 2009 Evolution of the neocortex a perspective from developmental biology Nature Reviews Neuroscience 10 10 724 35 doi 10 1038 nrn2719 PMC 2913577 PMID 19763105 Rakic P May 1972 Mode of cell migration to the superficial layers of fetal monkey neocortex The Journal of Comparative Neurology 145 1 61 83 doi 10 1002 cne 901450105 PMID 4624784 S2CID 41001390 Rakic P 1 February 1974 Neurons in rhesus monkey visual cortex systematic relation between time of origin and eventual disposition Science 183 4123 425 7 doi 10 1126 science 183 4123 425 PMID 4203022 S2CID 10881759 Yuste R Peinado A Katz LC 31 July 1992 Neuronal domains in developing neocortex Science 257 5070 665 9 doi 10 1126 science 1496379 PMID 1496379 Torii M Hashimoto Torii K Levitt P Rakic P 24 September 2009 Integration of neuronal clones in the radial cortical columns by EphA and ephrin A signalling Nature 461 7263 524 8 doi 10 1038 nature08362 PMC 2874978 PMID 19759535 Ackman JB Burbridge TJ Crair MC 11 October 2012 Retinal waves coordinate patterned activity throughout the developing visual system Nature 490 7419 219 25 doi 10 1038 nature11529 PMC 3962269 PMID 23060192 Retrieved from https en wikipedia org w index php title Radial unit hypothesis amp oldid 1149938503, wikipedia, wiki, book, books, library,
