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The role of nerves in the regulation of regeneration
Published in David M. Gardiner, Regenerative Engineering and Developmental Biology, 2017
In contrast to the extensive phenomenology with regard to the role of nerves in regeneration, relatively little is known about the function of nerves in controlling embryonic development. The behavior of nerves during embryogenesis has been well studied for both the central nervous system (CNS) and the peripheral nervous system (PNS) and is the basis for the expanding field of developmental neurobiology. Such studies have focused on how axons find their way to target cells and tissues and have led to a comprehensive understanding of axon guidance and path finding. Moreover, much focus is now on what happens when two nerves interact to form the complex synaptic network of the CNS. Similarly, the growth cone of the extending axon in the PNS reaches its target muscle cells, leading to the formation of the neuromuscular junction (NMJ). From these studies, it is evident that these interactions are mutual and reciprocal, such that neurons that are unable to find a target or targets that do not get innervated fail to survive (Gilbert 2013; Wolpert et al. 2015). The signals regulating these interactions between developing nerves and muscle (e.g., neurotropic factors) have been well characterized.
Posthumanism: Creation of ‘New Men’ Through Technological Innovation
Published in The New Bioethics, 2021
The environment influences intelligence and disentangling the contributions of genes from that of the environment is difficult; it might also influence how heritable IQ is. It is not just that both nature and nurture matter, but that they influence each other in different ways in different people. Reviews of the field of intelligence found that heritability of IQ varies significantly by social class. The importance of the environment for IQ is established by a 12-point to 18-point increase in IQ when children are adopted from working-class to middle-class homes (Nisbett et al. 2012a). Moreover, group differences in IQ are best understood as environmental in origin (Nisbett et al. 2012b). A case–control GWAS consisting of 1238 individuals of extremely high IQ and 8172 unselected population-based controls identified an SNP with the highest heritability known for a cognitive phenotype. Three variants in the ADAM12 locus encoding disintegrin and metalloproteinase domain-containing protein 12 were associated with extremely high IQ, as well as with the Plexin protein-expressing gene family plexins of the plexin-semaphorin pathway. This pathway has been linked to axon guidance, mental disability and neural connectivity, axon regeneration in the central nervous system, bone disorders, cancer and inflammatory diseases (Zabaneh et al. 2018).