Neural Nanoblocker (IMAGE) Brown University Caption Metal catalysts -- nickel and particularly yttrium -- used to create carbon nanotubes can block a key signaling pathway in neurons. Experiments show the metal particles tend to plug cellular pores normally reserved for calcium ions. Credit Lorin Jakubek / Brown University 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.