Using fMRI in awake human infants to study functional development of cortex

点击翻译按钮获取中文摘要

Project Summary In the last two decades, functional neuroimaging has providing a stunning window into the function of the human brain. When a person looks around the world, for example, systematic patterns of activity emerge in the cortex, related to both visual properties (e.g. the size or position) and also conceptual properties (e.g. object versus human versus natural scene) of the experience. These patterns of cortical activity are remarkably consistent across different adults, but very little is known about when, or how, they develop. Understanding the timing and mechanism of typical brain development is a necessary foundation for identifying the cause of neuro-developmental disorders that affect cognitive development, and for assessing the efficts of early rehabilitation. One reason these questions remain unanswered is the limited methods available for neuroimaging in awake human infants. To measure functional responses in the whole cortex with high spatial resolution, the ideal technique is functional magnetic resonance imaging (fMRI); however, it is extremely challenging to acquire high-quality fMRI data from infants while they are awake. One challenge is participant motion. Moving a millimeter is enough to destroy a MR image. Infants cannot be instructed to lie still, and cannot be held tightly because their skulls are soft (and because they must be comfortable during the experiment). The first aim of the proposed research is to address the challenges of fMRI in infants, and collect high quality data from awake human infants while they watch dynamic, bright colored, infant-friendly movies. Technical innovations necessary to achieve this aim include novel flexible experimental designs, custom-built coil sized for an infant's head, a special protocol for scanning the infant with a parent in the MRI, custom-written quiet MRI sequences, and special procedures for data analysis. The second aim is to compute and compare the responses to 60 blocks of movies (including children's faces and bodies, toys, natural scenes, and textures) in twenty full-term infants aged 4-8 months and in adults. The patterns of responses across movies can also be used to compare the predictions of alternative theories of both initial state and learning mechanisms in infant cortex. Finally, when cortex changes over development, a fundamental question is whether this change is driven by learning from visual experience, or by maturation of the biological mechanism. Because visual experience is extremely limited in utero, a natural dissociation of these factors occurs in the case of moderately preterm birth. Measuring the development of cortical responses in full-term and moderately preterm infants will also provide an important foundation for studies of infants born very preterm, who are at high risk for neurological and developmental disorders.