Silent Synapses (IMAGE) Columbia University Irving Medical Center Caption Only 20 percent of synapses (red) were observed to transmit dopamine. The rest (green) were found to be silent. Credit Sulzer Lab/Columbia University Medical Center Usage Restrictions None 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.