"Second Brain" (IMAGE) Michigan State University Caption A network of glial cells, the logic gates of the gut’s nervous system, are seen in this micrograph. The cells — the dark orbs enveloped in gray — have been colorized according to how they respond to a chemical signal. Credit Credit: Proc. Natl. Acad. Sci./Gulbransen Lab Usage Restrictions None. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.