Frequency-dependent BOLD fMRI to somatosensory stimuli in dexmedetomidine-anesthetized rats

Motivation: Different anesthesia methods have different physiological effects on the cortex and subcortex, resulting in inconsistent activation strength during fMRI. Goal(s): To investigate the frequency-dependent fMRI activation of somatosensory pathways evoked by electrical stimulation of the rat forelimb under dextrotomidine sedation. Approach: We conducted fMRI on 9 rats using an 11.7T animal scanner with EPI, applying classical forelimb stimulation under dexmedetomidine anesthesia. Results: We observed brain-wide activation in response to forelimb stimulation, with distinct patterns across regions. Notably, frequency-dependent BOLD responses were most significant at 4 and 8 Hz in S1 and S2, while elevated FWHM also detected in VPL, Po, SC, and SV. Impact: Bilateral forelimb stimulation activated S1FL, S2, VPL, and Po under dexmedetomidine anesthesia. High-frequency stimulation also induced strong onset activation in these regions, while no offset activation. This suggests dexmedetomidine is a promising anesthetic reflecting the physiological state like awake animals.