Understanding and promoting plasticity within the human visual cortex

点击翻译按钮获取中文摘要

One basic difference between children and adults is that children's brains have a much greater propensity for change; i.e. children's brains are more `plastic' than adult brains. Reduced plasticity in the adult brain has direct implications for the learning of new skills and recovery from damage to the brain through trauma, disease or abnormal development. The proposed research will address two key questions: 1) how can plasticity be increased in the healthy adult human brain? and, 2) how and why does human brain plasticity decrease with age? The research will focus on visual brain areas because there is a wealth of neuroscientific data relating to visual cortex development and plasticity in animals that can directly inform research into human brain plasticity. One potential technique for increasing human brain plasticity is transcranial direct current stimulation (tDCS), which allows for safe and painless stimulation of the human brain. It has been found that tDCS can reduce neural inhibition within the stimulated brain area. This is important, as inhibition has recently been shown to block plasticity in the visual cortex of adult animals. The proposed research will explore the effect of tDCS on inhibition in the adult human visual cortex using behavioural measures and advanced brain imaging techniques. Furthermore, the effect of tDCS on a basic measure of visual cortex plasticity called long-term potentiation (LTP) will be investigated. LTP involves the repetitive presentation of a visual stimulus. This triggers cortical plasticity that can be measured as a temporary increase in the electrical response of visual brain areas. Finally, the ability of tDCS to enhance learning of a visual task will be tested in adult participants. In a parallel line of research, visual cortex inhibition and plasticity will be measured in children and adults from 5-40 years of age. This study will use LTP and a behavioural measure of inhibition to identify whether the loss of visual cortex plasticity with increasing age is abrupt or gradual and whether it is related to an increase in visual cortex inhibition. The proposed research will have a significant impact in the field of human neuroscience, as it will provide new insights into the fundamental processes that influence learning and the acquisition of new skills. Furthermore, the research may reveal new ways of increasing the rate and capacity of learning in adulthood. This has clear implications for education and training across the lifespan. In the longer term this information will support the development of rehabilitation strategies for the effects of brain injury and abnormal brain development in older children and adults. The proposed research will provide specialized training to at least nine highly qualified personnel in Canada and will provide a foundation for long-term collaborative research in the area of human visual development and plasticity.