Multi-parametric vascular and metabolic MRI for the study of cerebral plasticity

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The brain is known to be a highly plastic organ, meaning that it has the lifelong ability to alter its structure and function following training to learn a new task and in response to physiological changes such as injury and lifestyle (e.g. diet or exercise). For example, it has been shown using magnetic resonance imaging (MRI) that learning a motor task such as juggling can lead to changes in brain structure and function. But while we know that the brain changes, the extent of these changes, their biological nature, whether these changes are maintained in the long term and whether they can be harnessed for disease recovery are all the subject of ongoing debate. This is because brain plasticity involves multiple subtle structural, vascular and metabolic changes. These changes are notoriously difficult to study in humans using single MRI techniques and small sample sizes. ***Most MRI research in Canada is done using 3 tesla (T) magnets, and many techniques exist at this field strength to study brain structure and function. Unfortunately, many of the techniques commonly used in research provide only limited information about the biological mechanisms that underlie the MRI signals. While less common, new and advanced techniques exist to look at more specific information such cerebral blood flow, blood volume, oxygen metabolism, veins and grey matter microstructure. Furthermore, higher magnetic fields (7T) can also be used, in combination with these advanced techniques, to help us understand the biological mechanisms at play with greater specificity and higher resolution. ***Here, we propose to use these advanced techniques at 3T and 7T to better understand the plasticity process. In this program, we will continue to develop the existing advanced vascular and metabolic techniques by extending models we have developed in the past. Also, we will combine advanced MRI techniques measuring brain structure, blood vessel anatomy and function, and metabolism to create novel metrics that better capture the biological plasticity process. These new metrics will be used, along with more established techniques, to study the complex patterns that characterize brain plasticity during motor learning tasks. These studies will involve bimanual piano playing and a finger pinching task, and will help establish the validity and sensitivity of the techniques developed here at 7T and at 3T. In the future, these techniques will also be used to study age-related and exercise-induced plasticity. Given that plasticity is an essential process of normal and abnormal brain function, and given the increasing interest in neuroimaging, the technical work developed here is expected to lead to highly cited publications. Furthermore, by training young scientists to have versatile and novel expertise in these fields, this program will promote their careers by making them in high demand and contribute to fostering innovative science in Canada.