This article provides an overview of submillimeter fMRI methodology to map layer-dependent functional connectivity across brain areas. With recent sequence advancements in fMRI contrast generation and readout strategies, it is possible to overcome previous limits of resolution, coverage, and venous contaminations. The layer-fMRI tools reviewed here provide a starting point for mapping layer-specific connections across the entire brain, in the context of cognitive neuroscience. Layer-fMRI using VASO represents a paradigm shift that promises to transform the methods driven field of layer-fMRI to the application domain and will make layer-fMRI a reliable tool of neuroscience in two important aspects. First, the ability to image the entire brain with sufficient sensitivity on UHF scanners around the world makes layer-fMRI tools applicable for neuroscience cortical circuitry questions without the need of extensive MR-physics expertise. Secondly, many influential network theories of brain function that posit distinct connection across individual cortical layers (e.g., predictive coding (Stephan et al. 2019), hierarchical processing streams) may now be directly tested in humans. This will allow a large field of researchers to investigate mechanisms behind any number of neuropsychological
