Penn State Feb 11 2026 Brain cells are constantly swallowing material from the fluid that surrounds them - signaling molecules, nutrients, even pieces of their own surfaces - in a process known as endocytosis that is essential for learning, memory and basic neural upkeep.  Now, new research by Penn State scientists has revealed this vital process may be governed by a previously unknown molecular gatekeeper: a lattice‑like structure just beneath the surface of brain cells, or neurons, called the