Santosh Bahadur Katwal1, James Christopher Gatenby2, John C. Gore3, Baxter P. Rogers4
1Electrical Engineering and Computer Science, Vanderbilt University Institute of Imaging Science (VUIIS), Nashville, TN, USA; 2Radiology and Radiological Sciences, Vanderbilt University Institute of Imaging Science (VUIIS), Nashville, TN, USA; 3Biomedical Engineering, Physics and Astronomy, Radiology and Radiological Sciences, Vanderbilt University Institute of Imaging Science (VUIIS), Nashville, TN, USA; 4Biomedical Engineering, Radiology and Radiological Sciences, Vanderbilt University Institute of Imaging Science (VUIIS), Nashville, TN, USA
Functional MRI (fMRI) at 7T has high signal-to-noise ratio (SNR) and high spatial and temporal resolution, which improve our ability to detect small differences in latency of the BOLD response. The differences in latency can imply causal relationships giving measures of directed influence of one neuronal system on another. We used Multivariate autoregressive (MAR) modeling and Granger causality to determine the directed influence measures and minimum resolvable latency difference of the BOLD response at 7T. Latencies, as low as 112 ms, were resolved in a single subject with just 16 trials. Bootstrapping was performed to obtain 95% confidence intervals on the results.