Over the last year, Peter A. Bandettini has directed the unit on Functional Imaging Methods in the Laboratory of Brain and Cognition. The over-reaching goals of the unit include a) better understanding of the neuronal correlates of and the variability of functional MRI signal changes ? including perfusion and BOLD changes, b) new types of neuronal contrast in MRI, c) development of integrated paradigm design, behavioral, and processing methods allowing improvement of the quality and usability of information obtain from fMRI time series data. Five of the most interesting findings over the past year include: 1. In Vitro detection, using MRI, of neuronal activity from spontaneous and synchronous spiking activity of rat fetal brain tissue. This is ongoing work in collaboration with Dr. Dietmar Plenz. We are working to confirm our findings and more clearly relate them to neuronal activity. Such a finding would introduce MRI as a new method for detecting neuronal activity directly. 2. Extraction of hemodynamic latency and width differences during a simultaneous word recognition and word rotation task, thereby dissecting relative processing bottlenecks across cortical regions in the human brain. This work with my past post docs, Dr. Patrick Bellgowan and Dr. Ziad Saad, has resulted in a paper which is the first of it?s kind reporting activation latency map differences on the order of 100 ms using fMRI. 3. Demonstration that the spatial extent of BOLD contrast is larger than previously thought, suggesting the possibility that weaker BOLD activation may result from subthreshold neuronal activity. This was performed with Dr. Ziad Saad. 4. Demonstration, using a novel multi-echo sequence, that what was thought to be T2 changes might instead arise from changes in either T1, proton density, or T2*. This has implications for quantification of BOLD contrast. This work was performed in collaboration with Dr. Wen-Ming Luh 5. Demonstration that regions in cortex involved in house/face decision making task show activity that is directly related to the absolute difference in the activity between the low level face/house fMRI activity. This study, in which I collaborated with Dr. Liuz Pessoa on, is the first demonstration of such an fMRI ?bootstrap? analysis to tease out hierarchal processing.
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