From Functional Organization to Vascular Structure in the Primate Visual Cortex Using Ultrasound Imaging

The primary visual cortex (V1) provides an exceptional structure to assess information encoding in the cortex thanks to its highly controlled visual input. However, optical measures and electrophysiology are limited to very superficial layers while fMRI provides low spatial resolution. Taking advantages of functional ultrasound imaging (fUSi), we examined large volumes of V1 in two awake non-human primates. We showed the conservation of retinotopic maps within deep sulcal regions and across cortical layers. We then assessed the cortical point image and compared it to its vasculature distribution through ultrasound localization microscopy (ULM). We further identified the smallest vascular compartment underlying the signal. Together, these results establish fUSi, complemented by ULM, as a minimally invasive mesoscale approach for resolving functional organization of the cortex in deep sulci.