Large-scale functional imaging techniques are part of a fast growing field of neuroscience aiming at understanding whole brain activity.Functional Ultrasound Imaging(fUS)is a new method monitoring changes in blood flow with a high spatial(~100μm)resolution and sampling rate(500Hz)for a typical imaged section of 1cm wide and 2cm deep,providing a more detailed image than fMRI.We used this technique to study the functional organization of auditory circuit from the inferior colliculus(IC)to the cortex in the awake ferret.We characterized the tonotopic organization of several areas of the auditory cortex in three dimensions,including deep sulci which are cortical regions typically unaccessible to standard intrinsic and voltage sensitive imaging techniques.Using a linear classifier algorithm,we found that blood flow activity gave access to a precise representation of the information encoded in the auditory cortex.This information was mostly present in medium and deep layers,mirroring previous studies that showed more refined tonotopic organization in granular and infragranular layers.Taking advantage of the penetration depth of fUS,we functionally isolated several thalamic nuclei,including the lateral geniculate nucleus(LGN)and the medial geniculate body(MGB).We describe for the first time the 3D functional tonotopic organization of the ferret MGB,confirming previous anatomical studies,and of the IC.Finally,we studied the main projections from prefrontal cortex to parabelt auditory areas at the level of the whole auditory cortex,unravelling a possible functional pathway for top-down control of auditory processing.