hide
Free keywords:
-
Abstract:
Awake rodent fMRI has been increasingly applied as a promising non-invasive imaging tool to investigate the organization of functional networks, thus providing the mechanistic understanding of the neural basis of brain-wide neurovascular coupling in both healthy and diseased animal models. This procedure could avoid impact on neural activity and hemodynamic responses by anesthetic agents. Therefore, the specific goal of this study is to implement an awake mouse fMRI protocol/data analysis both during resting state and under visual stimulation, with a relatively short training paradigm and without modification of conventional scanner setup. All procedures in this study were conducted in accordance with guidelines set by the Institutional Animal Care and Use Committee of Michigan State University. 3 Mice were habituated for 7 days: 4 days in the mock scanner with FLASH/EPI/RARE sound and 3 remaining days in the 7T Bruker scanner. We evaluated this protocol by measuring the fMRI signal over the whole brain first using task fMRI with visual stimulation of 5 Hz on both eyes and then using resting-state fMRI (rs-fMRI). The fMRI data from the last day with 30-min fMRI scanning (spatial resolution: 0.3 mm × 0.3 mm × 0.5 mm, 20 slices, TR: 1s) in wakefulness were used for analysis. Each rs-fMRI scan acquired 400-time points (6 min 40s). The preprocessing procedures for rs-fMRI include motion correction, despike, t-shift, spatial blurring, 0.01-0.1 Hz bandpass filtering in AFNI, and ICA denoising in FSL. In the task fMRI, we observed a robust evoked BOLD-fMRI in the primary visual cortex (V1), higher-order visual area (V2), dorsal lateral geniculate nucleus (LGd), and superior colliculus (SCs). In the rs-fMRI, we observed a strong default-mode network, including the prelimbic cortex, cingulate cortex, posterior parietal cortex, and retrosplenial cortex. In summary, this awake mouse protocol allows whole-brain mice imaging in the awake state without modifications to the scanner’s hardware, using a relatively short training paradigm.
