Unlike other primates, the slower rate of development of the human brain results in its fourfold increase in volume between birth and adulthood and during this time frame there are also significant changes in cognitive ability, the most marked of which occurs in early infancy. It is only relatively recently, with the advancement of neuroimaging technology, that researchers have begun to examine how brain structure, that is its physical fabric and organisation, might relate to its function, i.e. the tasks it performs, in a child's developing brain. One view is that we are born with an innate ability to process information and therefore that structure influences function. A contrasting view is that brain structure is shaped and refined as it carries out cognitive tasks and interacts and learns from the environment. This essay will first outline some basic processes involved in postnatal brain development. Using research evidence, in the field of language, it will then examine three different approaches to understanding the relationship between structure and function in the developing brain and the extent to which one influences the other.
Human brain development is similar to that of other primates, but differs in that it happens much more slowly, which confers particular benefits on the species. Firstly, it allows a larger volume of cerebral cortex and in particular a large prefrontal cortex to develop and secondly it allows a long phase of postnatal brain development, outside of the womb, during which the brain experiences significant structural changes concurrently with interactions with the external environment (Mareschal, D. et al. 2004, p 122). At birth there is a rapid increase in neural connectivity in most brain regions with information initially being processed in a random fashion and gradually becoming handled in a more orderly and specialized way. Neural circuits that are well used remain and become more encapsulated i.e. more differentiated in function, whilst those that are used infrequently will fade (Changeux, 1985). Another important concept at this stage is that of plasticity (Reilly et al.1998), the idea that if a part of the infant brain is damaged, another healthy part can take over its functioning. As development progresses, brain structure and function become increasingly more specialized until they finally reach their mature adult form, when particular regions of the cerebral cortex take on the responsibility for processing particular types of information in functional units known as modules, for example, language processing takes place in the left temporal lobe (Neville et al. 1993). There are two types of module, physical structural modules known as neural modules and cognitive modules which refer to “hypothetical constructs” (Mareschal, D. et al. 2004, p127) that allow psychologists to propose and test hypotheses about how brain functions might be performed. One way that they do this is by using connectionist computer modelling.
Although there is general agreement that the brain operates in a modular way, there are conflicting views as to how this happens. One view held by Fodor (1983) which is a nativist standpoint, is that structural brain development is genetically pre-determined, whereby advances in cognitive ability and therefore functioning, are as a direct result of maturation of particular cortical regions. Thus, brain structure influences brain function. He also believed that the human brain has become modular through adaptation to the environment during the course of evolution (a phylogenetic process) and modularity is therefore innate. A key feature of Fodor's theory of modularity of mind is the concept of domain-specificity, that is that specific cognitive modules process specific pieces of information in isolation from the tasks that other modules perform.
A contrasting view is held by Karmiloff-Smith (1992) who takes a more epigenetic stance, believing that,...
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