“Super Bizarre” – Neuroscientists Discover That Adult Brain Is Filled With Millions of “Silent Synapses”

MIT researchers found that about 30% of synapses in adult mouse cortex are silent connections.

These silent synapses are located on filopodia, which are ~10 times more common in adult mouse brain than previously reported.

Filopodia synapses contain NMDA receptors but lack AMPA receptors and are inactive until activated.

Pairing glutamate release with brief postsynaptic depolarization caused AMPA receptors to accumulate and the synapses to become functional within minutes.