Scientists from Harvard Medical School, the Broad Institute, and Weill Cornell Medicine have elucidated how the brain rapidly redirects blood flow to active regions. Utilizing optogenetics and visual stimuli in mice, they identified connexin protein clusters in brain blood vessel linings that enable intercellular communication and vasodilation propagation. Disruption of connexins Cx37 and Cx40 impaired this signaling, reducing vessel dilation. This novel insight into neurovascular coupling may inform therapies targeting neurodegenerative diseases with vascular components.