The Mosaic Model Of Brain Development

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Some have argued that mammalian brain development is constrained by a variety of factors, including a physiological necessity to develop in an overall isometric pattern. However, Hager, Lu, Rosen, and Williams (2012) argued against that position. Based on observations, they recognized that mammals of the same species with brains that were matched according to weight, frequently exhibited significantly different sizes in Cross subject comparisons of the same brain region. To further evaluate this, they analyzed over 10,000 mice noting several different regions of the brain and made comparisons. They did not find any significant phenotype correlation, thus supporting what is referred to as the Mosaic model of brain evolution. Furthermore, they …show more content…

Clearly not all organisms possess a brain, and there is a vast range of brains in terms of size, composition, structure, degree of sophistication, and functional areas of specialization. However, not all organisms are in need of a brain. Historically, a great deal of research regarding sensitization and learning has been conducted using a marine invertebrate, the Aplysia. Specifically, the sensitization studies that have been performed on tens of thousands of these mollusks have revealed a great deal of information on the neurophysiological and neurochemical adaptations that occur during the development of sensitization and habituation (Cooper, Bloom, & Roth, 1996). In considering this, one must understand that the effect of the sensitization can last over an extended period of time before finally returning to baseline levels. What is this, if not memory? How is it possible for an invertebrate mollusk to retain information and behave in a manner that requires the acknowledgment of some type of memory? The answer is very simple. Apex animals such as humans remember things in the same way: we undergo a series of neurochemical and morphological changes that actually modify the structure of our brains, at least at the level of the neuron. If these changes are reinforced by repeated excitation of the specific neural pathways involved in storage or retrieval of the memory, or in the afferent to efferent pathways in the case of behavioral matters, the changes become long-lasting, or even permanent. Conceptually, the memory process of Homo Sapiens with our elaborate and elegant brains, and the Aplysia, with its simple, non-centralized nervous system, is the

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