The delineation of discrete regions of cortex---whether through characterizing micro-architecture, topography, connectivity, or function---has persisted as a focus of neuroscience research since the past century. While the introduction of functional magnetic resonance imaging (fMRI) into the toolbox of cognitive neuroscience enabled remarkable strides in functional localization, the description of anatomy nonetheless continues to rely on standard anatomical maps with cytoarchitectonically-defined subdivisions. Though fruitful, such parcellation maps are inherently independent of the brains under investigation. A promising alternative comes from a long-recognized defining feature of neural structure: connectivity. Parcellation based on differential connectivity has been prolific in describing macaque monkey cortex, and emerging non-invasive techniques now enable such mapping of human neuroanatomy.
After briefly reviewing the history of cortical mapping, I will describe the emergence and methodologies of a non-invasive connectivity mapping technique: resting-state functional connectivity with fMRI (rsfc-fMRI). Based on correlations of spontaneous intrinsic fluctuations in BOLD signal, rsfc-fMRI provides a means of describing functional connectivity that is highly consistent with anatomical connectivity (using diffusion tensor imaging) and tract tracing studies in the macaque monkey. The advantage of a short acquisition time (~5 minutes) and the absence of task demands also facilitate application to clinical and developmental questions, as well as cross-species comparative studies. I will present connectivity-based subdivisions which have been observed in functionally heterogeneous regions such as the anterior cingulate and precuneus, as well as research on the variability of large-scale networks across individuals.

The talk will conclude with a short video addressing the history and controversies within resting-state fMRI research.