Connections in the Olfactory Circuit (IMAGE) California Institute of Technology Caption The TRACT method allows for the identification of neurons connected by synapses in a brain circuit. This image shows the olfactory receptor neurons (red) activating the production of a green protein in their synaptically-connected downstream partners. Credit Courtesy of the Lois Laboratory Usage Restrictions with image credit License Licensed 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.