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Principles of neuromotor development
Published in Mijna Hadders-Algra, Kirsten R. Heineman, The Infant Motor Profile, 2021
Mijna Hadders-Algra, Kirsten R. Heineman
The cortical subplate is a structure between the cortical plate and the future white matter (Figure 2.2). It is the major site of neuronal differentiation and synaptogenesis in the cortex, it receives the first ingrowing cortical afferents (e.g., from the thalamus), and it is the main site of synaptic activity in the mid-foetal brain (Kostović et al. 2015). This implies that the subplate is a major mediator of foetal motor behaviour (Hadders-Algra 2018b). The subplate is thickest between 28 and 34 weeks PMA. Before that age, from 25 to 26 weeks onwards, subplate neurons start to die off gradually, and later-generated neurons begin to populate the cortical plate. These developmental changes are accompanied by a relocation of the thalamocortical afferents, which now grow to their final target in the cortical plate (Kostović et al. 2014a).
Developmental Diseases of the Nervous System
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
James H. Tonsgard, Nikolas Mata-Machado
Formation of the mature nervous system is dependent on the induction or formation of precursor cells, followed by the proliferation and maturation of cells within periventricular germinal centers and finally, migration to their intended sites. A cross section of the developing brain shows that it is initially organized into an outer pial (preplate) or marginal zone (MZ) and inner ventricular zone (VZ) (Figure 9.4a). Stem cells proliferate and differentiate into immature neurons and glial precursors within the VZ and subventricular zone (SVZ). Starting in the seventh fetal week, neuroblasts in the VZ migrate upward to form a subpial preplate zone (PP). Subsequently, neurons migrate into the PP (Figure 9.4c1). These neurons divide, with some forming the superficial molecular layer or MZ (layer I) and others moving to the deep subplate. Thereafter, waves of neurons pass through the subplate, successively forming layers VI, V, IV, III, and II in an inside-out pattern, with the last neurons moving into layer II (Figure 9.4b, c3).
Methodology
Published in Lena Hellström-Westas, Linda S. de Vries, Ingmar Rosén, Atlas of AMPLITUDE-INTEGRATED EEGs in the NEWBORN, 2008
Lena Hellström-Westas, Linda S de Vries, Ingmar Rosén
During fetal development, and also including the first period of life in the extremely preterm infant, a transient fetal subplate zone is situated between the white matter and the cortical plate. The fetal subplate zone is the origin of thalamocortical and corticocortical afferents and probably contributes to EEG activity both directly and indirectly via its cortical connections.2 The subplate zone is of particular interest for the mechanisms underlying the spontaneous activity transients (SATs), which are dominated by very low frequency waves with higher frequency components superimposed, a predominant feature of the early preterm EEG.3–5
Finite element analysis of 3D-printed personalized titanium plates for mandibular angle fracture
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Yan Li, Hui Li, Qingguo Lai, Runqi Xue, Kaiwen Zhu, Yanwei Deng
Mandibular angle fracture is a common type of maxillofacial fracture. In the field of oral and maxillofacial surgery, the research on the treatment of mandibular angle fracture mainly focuses on the biomechanical evaluation of different internal fixation techniques. In the 1970s, Champy et al. (1978) proposed the theory of tension band using a single titanium plate for rigid internal fixation along the tension band area of the mandibular oblique line. However, many researchers (Feller et al. 2003) saw that using a single titanium plate for rigid internal fixation along the tension band area of mandibular was only suitable for the mandibular angle fractures with favorable and mild displacement. In addition, it was also found that the stability was poor and leaded to higher risk of postoperative infections (Al-Moraissi et al. 2014; Levy et al. 1991). And the plate itself has stress shielding effect (Kennady et al. 1989). With the extension of plate fixation time, subplate cortical bone absorption became thinner, bone density decreased, and osteoporosis-like changes gradually appeared. Therefore, how to expand the indications of tension band theory, improve the stability of fracture after titanium plate fixation and reduce stress shielding effect remains to be solved.
Acute symptomatic neonatal seizures, brain injury, and long-term outcome: The role of neuroprotective strategies
Published in Expert Review of Neurotherapeutics, 2021
Francesco Pisani, Carlo Fusco, Lakshmi Nagarajan, Carlotta Spagnoli
The main predisposing factors to IVH are the immaturity of the vasculature of the germinal matrix and its passivity to systemic blood pressure changes, which are typical of preterm newborns. White matter injury can be favored by cerebral oxygenation changes, infection, and inflammation, but also by intrinsic vulnerability to oxidative stress under hypoxic-ischemic conditions [40,41], which are in turn favored by immature vascular supply and autoregulation mechanisms [40,42]. In the acute phase, injury to the subplate neurons can transiently increase cortical excitability [43], resulting in acute seizures. The ensuing disruption of projection and association fibers and the secondary effects on the cortical plate and its connections to the thalamus are thought to be key determinants for long-term outcomes, especially relating to epilepsy and cognition [44].
Neural Organoids and the Precautionary Principle
Published in The American Journal of Bioethics, 2021
Jonathan Birch, Heather Browning
If organoids are developed with a discernible midbrain, thalamus or cortical subplate, what response would be proportionate? The most obvious precaution is that, in these circumstances, the organoids should be brought within the regulatory frameworks that currently exist in many countries for scientific research on sentient animals. The UK already has a rigorous framework based on the Animals (Scientific Procedures) Act 1986 (“ASPA”), requiring ethical review, a careful weighing of harms and benefits, and evidence that scientists have duly considered the imperative to reduce, refine, and replace. We suggest it would be a proportionate response to bring any organoid displaying neurological “warning signs” of sentience within the scope of ASPA. As we understand it, the technology is not there yet, but, given the slow pace of regulatory change in relation to scientific progress, it would be wise to prepare the necessary regulatory changes now.