![]() ![]() ![]() For example, gene expression can be altered by specific experiences, and this in turn can lead to organizational changes in the nervous system. More importantly, however, it is now recognized that epigenetic changes, which can be defined as changes in developmental outcomes, including regulation of gene expression, are based upon mechanisms other than DNA itself ( Blumberg, Freeman, & Robinson, 2010). The second phase, which is both preand postnatal in humans, is a time when the connectivity of the brain is very sensitive not only to the environment but also to the patterns of brain activity produced by experiences. In most mammals the first reflects a genetically determined sequence of events in utero that can be modulated by maternal environment. ![]() It became obvious in the early 20 th century that brain development reflected a series of stages that we can now see as being broadly divided into two phases. This idea was so appealing that it was widely believed until well into the 19 th century. Some 2000 years ago the Roman philosopher Seneca proposed that a human embryo is an adult in miniature and thus the task of development is simply to grow bigger. There is little reason to believe, however, that other brain structures will not be changed in similar ways. In addition, the discussion will be biased towards plasticity in cerebral structures because most of what we know about modulation of brain development is based upon studies of cerebral development. Because most of what we know about brain plasticity and behaviour in development comes from studies of the laboratory rat our discussion will focus on the rat but will consider humans when possible. ![]() We begin with an overview of brain development, followed by a brief review of principles of brain plasticity and finally a consideration of how factors influence brain development and adult behaviour. The goal of the current article is to review the ways the developing brain can be sculpted by a wide range of pre- and postnatal factors. Brains exposed to different environmental events such as sensory stimuli, drugs, diet, hormones, or stress thus may develop in very different ways. The development of the brain reflects more than the simple unfolding of a genetic blueprint but rather reflects a complex dance of genetic and experiential factors that shape the emerging brain. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |