David Ress1, Reswanul Khan2, Bharath Chandresekaran3, Seth Koslov3
1Neurobiology, Psychology, Imaging Research Center, Center for Perceptual Systems, The University of Texas at Austin, Austin, TX, United States; 2Neurobiology, Physics, Imaging Research Center, Center for Perceptual Systems, The University of Texas at Austin, Austin, TX, United States; 3Communication Sciences and Disorders, The University of Texas at Austin, Austin, TX, United States
We present a high-resolution sparse-sampling fMRI approach for imaging small auditory brainstem structures. High resolution is obtained with a multi-shot spiral acquisition. Sparse sampling is obtained by two adjustments to the fMRI pulse sequence. First, quiet periods are created by disabling the acquisition gradients for long periods (9 s) to permit delivery of auditory stimuli. Second T1-equilibrium is maintained by continual delivery of slice-selective excitation pulses throughout each scanning run. Using this approach, we have obtained 1.2-mm sampling in human inferior colliculus (IC) with satisfactory contrast-to-noise ratio. The data confirm a laminar organization of stimulus frequency representation in human IC.
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