Knockout (IMAGE) Picower Institute at MIT Caption Researchers used a genetic technique to knock out NMDA receptors in layer 4 of the visual cortex of mice. Credit Bear Lab/ Picower Institute for Learning and Memory Usage Restrictions with 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.