Mesoscale functional magnetic resonance imaging at 3T in awake behaving monkeys

Recent progress in high-resolution non-invasive imaging in humans confirmed the existence of columnar structures known in the monkey. These fMRI experiments fueled the hope to identify mesoscale functional structures in largely unexplored cortical territories. Using implanted phased array coils and contrast-agent enhanced fMRI (e.g. Janssens et al., Neuroimage 2012; Li et al., CC 2018, Zhu and Vanduffel PNAS 2019), we started to map the cortex of rhesus monkeys with 0.6 mm isotropic voxels covering the entire brain and with a large variety of visual stimuli. In my talk, I will present novel unpublished data showing highly reliable mesoscopic functional modules which are present in occipital, parietal, temporal and frontal cortex. I will start by showing proof-of-principle data from posterior regions of the visual cortex which are known to contain very specific functional sub-compartments and continue by revealing a columnar-like organization in major parts of visual cortex and beyond. I will argue that the fine-grained functional organization of extrastriate cortex is considerably more complex than suggested by currently prevailing parcellation models, based on electrophysiology and low-resolution fMRI evidence. The identification and the functional-anatomical characterization of the entire columnar alphabet will be key to understand vision.