15 matches found for How People Learn Brain,Mind,Experience,and School Expanded Edition. in Part I: EVOLUTIONARY ORIGINS OF NEURONS AND NERVOUS SYSTEMS
Select a page to see where your word(s) or phrase(s) are located in the OpenBook. Excerpts from the chapter provide context.
At the bottom of
page 1...
... EVOLUTIONARY ORIGINS OF NEURONS AND NERVOUS SYSTEMS...
At the bottom of
page 1...
... The first three chapters address the ancient history of neuron-related molecules and centralized nervous systems. In Chapter 1, Cecilia Conaco and colleagues review earlier findings that many of the molecules found in neuronal synapses, especially within the postsynaptic density, predate the ... with a novel function, namely to build synapses. Thus, the research has moved beyond the relatively simple task of homologizing individual genes and begun to trace the evolution of complex and changing gene networks. An interesting, if as yet barely explored, implication of the idea that gene ...
At the bottom of
page 1...
... the major driving force behind neuronal action potentials? The answer is probably because Na was plentiful in the ocean, where neurons first evolved, and because Na influx tends not to interfere with intracellular calcium signaling. Once incorporated into neurons, Na-v channels...
At the bottom of
page 2...
... modified in diverse, interesting ways. For example, they evolved regulatory sequences that allowed them to be clustered at the axon initial segment and at Nodes of Ranvier in myelinated axons. Additional modifications evolved after the ancestral Na-v gene was duplicated, once near the origin of ... and then again (repeatedly) in several vertebrate lineages. One of the most interesting Na-v modifications is the evolution of resistance to TTX, which ... blocks Na-v channels, in pufferfishes and other species that use TTX to ward off predators....
At the bottom of
page 2...
... Glenn Northcutt analyzes, in Chapter 3, when and in which lineages complex brains evolved. Favoring a cladistic approach, Northcutt concludes that the last common ancestor of all bilaterian animals, ... 600–700 Mya, probably had a diffusely organized nervous system. Cephalic neural ganglia apparently evolved soon thereafter and were retained in many lineages. Truly complex brains evolved even later and did so repeatedly, in mollusks, arthropods, and chordates (including ... sharply with the conclusions of other researchers, who are struck by similarities in developmental gene expression patterns among vertebrate, insect, and annelid nervous systems. To them, these similarities must represent homologies. That is, they argue that similar gene expression patterns must have ... in the last common ancestor of fruit flies, vertebrates, and worms. Northcutt begs to differ, arguing that the expression of these genes in brains is caused by convergent evolution, perhaps by the co-option of ...
A total of pages of uncorrected, machine-read text were searched in this chapter. Please note that the searchable text may be scanned, uncorrected text, and should be presumed inaccurate. Page images should be used as the authoritative version.