Cerebral blood volume sensitive layer-fMRI in the human auditory cortex at 7 Tesla: Challenges and capabilities

Abstract

AbstractThe development of ultra high field (UHF) fMRI signal readout strategies and contrasts has led to the possibility of imaging the human brain in vivo and non-invasively at increasingly higher spatial resolutions of cortical layers and columns. One emergent layer-fMRI acquisition method with increasing popularity is the cerebral blood volume (CBV) sensitive sequence named vascular space occupancy (VASO). This approach has been shown to be mostly sensitive to locally-specific changes of laminar microvasculature, without unwanted biases of trans-laminar draining veins. Until now, however, VASO has not been applied in the technically challenging cortical area of the primary auditory cortex. Here, we developed a VASO imaging protocol for auditory neuroscientific applications. We describe the main challenges we encountered and the solutions we have adopted to mitigate them. With our optimized protocol, we investigate laminar responses to sounds. Finally, as proof of concept for future investigations, we map the topographic representation of frequency preference (tonotopy) in the auditory cortex.HighlightsLayer fMRI VASO in the auditory cortex is challenging due to its physiologyAfter protocol optimization we show the applicability of VASO to the auditory cortexTopographic maps obtained with VASO respect the large-scale tonotopic organization that has previously been shown with BOLD fMRI data.