MIT scientists discover millions of “silent synapses” in the adult brain

MIT scientists discover millions of “silent synapses” in the adult brain | ScienceDaily Science News from research organizations MIT scientists discover millions of “silent synapses” in the adult brain Your brain may be packed with hidden backup connections, waiting to turn new experiences into lasting memories. Date: May 6, 2026 Source: Massachusetts Institute of Technology Summary: MIT neuroscientists have uncovered a surprising secret hidden in the adult brain: millions of “silent synapses,” dormant connections that lie in wait until new learning calls them into action. Once thought to exist only in early development, these inactive links make up about 30% of synapses in the adult cortex and can be rapidly activated to form fresh memories. Share: Facebook Twitter Pinterest LinkedIN Email FULL STORY The adult brain contains millions of hidden “silent synapses” that can be activated to form new memories on demand. This built-in reserve helps us learn new things without erasing what we already know. Credit: Shutterstock MIT neuroscientists have uncovered a surprising feature of the adult brain. It contains millions of "silent synapses," which are immature connections between neurons that remain inactive until they are needed to help form new memories. For many years, scientists believed these silent synapses existed only during early development, when the brain is rapidly learning about the world. But the MIT team found that in adult mice, roughly 30 percent of synapses in the brain's cortex are still silent. This suggests the adult brain holds a large reserve of unused connections that can be activated when new information arrives. Researchers say this hidden pool of synapses may explain how the brain continues to learn throughout life without disrupting existing memories. "These silent synapses are looking for new connections, and when important new information is presented, connections between the relevant neurons are strengthened. This lets the br