Scientists Just Found a Fundamental Part of what makes your Brain Cells So Plastic

Researchers at the Picower Institute for Learning and Memory at MIT have found is that when one connection (aka a synapse) in the brain becomes stronger, neighbouring synapses immediately weaken, to stop the neurons from being overwhelmed - and there's a special protein at play here. "Collective behaviours of complex systems always have simple rules," says MIT neuroscientist and senior study author Mriganka Sur. "When one synapse goes up, within 50 micrometres there is a decrease in the strength of other synapses."

The team then discovered that AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptors were correlated with the weaking and strengthening of those synapses. They used a specially made chemical tag that tracked the expression of the regulator of AMPA receptors, a protein called ARC, to determine what was causing the changes.

What they found was that synapses with less ARC protein were able to express more AMPA receptors, but increased ARC in neighbouring spines caused those synapses to express less. "We think ARC maintains a balance of synaptic resources," says Jacque Pak Kan Ip, another neurologist and co-first author from MIT. "If something goes up, something must go down. That's the major role of ARC."