A new theory suggests our brains form the exact opposite patterns of electrical activity to our original memories.
In the last century, the discovery of “antimatter” revolutionized our understanding of the universe and the laws of physics. Antimatter refers to a “mirror image” material of subatomic particles of matter, like electrons, protons, and quarks, but with the opposite charge.
With the help of the Large Hadron Collider (LHC), researchers at CERN were able to confirm the fundamental symmetry between matter and antimatter, but there’s still a lot to learn about the mysterious substance.
Now, this same idea of a “mirror image” is being proposed to explain something just as perplexing as the universe: our minds.
In particular, researchers at the University of Oxford and University College London have been investigating the patterns in our brains when we form memories, coming to striking new findings about “antimemories,” which have been published in the journal Neuron.
Given the recent finding that our memories can store a petabyte of information — or basically the entire internet — scientists were shocked to discover that our brain’s memory capacity is 10x larger than previously thought, which in a way adds to the mystery since many of us can’t seem to remember where we left our phones or car keys on any given day.
Indeed, our memories are strange — we can have false memories, which is when we remember something that didn’t actually happen, and our memories can be erased or even changed with various technologies or memory-shaping techniques.
But at the level of the neuron, what’s actually happening in our heads when we form new memories or forget others? When memories are created or recalled, new electrical connections are either formed or strengthened between neurons in the brain.
Now, a new theory suggests that at the same time that the memory is created in our brains, an “antimemory” is also born — meaning that neuronal connections are made that generate the exact opposite pattern of electrical activity to the original memory.
According to the scientists, this could help maintain the balance of electrical activity in the brain. In fact, without this electrical balance, researchers believe that overly excited neurons could contribute to conditions like schizophrenia, epilepsy, and autism.
Scientists had already studied antimemories in rats, mice, and theoretical models, but until this most recent study, it was still a mystery how these memories might function in humans.
The researchers used functional magnetic resonance imaging (fMRI) to take a thorough look at the brain activity of volunteers as they formed associative memories of pairs of shapes.
"Over 24 hours, the shape associations in the brain became silent. That could have been because the brain was rebalanced or it could simply be that the associations were forgotten," neuroscientist Helen Barron from the University of Oxford said in a press statement.
"So the following day, some of the volunteers undertook additional tests to confirm that the silencing was a consequence of rebalancing. If the memories were present but silenced by inhibitory replicas, we thought that it should be possible to re-express the memories by suppressing inhibitory activity.”
Then the team used transcranial direct current stimulation (tDCS) in order to send low currents of electricity to the participants’ brains. With this technique, the researchers were able to suppress the concentration of certain chemicals in the brain, including GABA, which is a chemical linked to inhibition.
By doing so, the researchers effectively reduced the activity of the antimemory inhibitory neurons, which means that the lost memories of the shape associations from earlier in the study were restored and came back to the volunteers.
"'We have shown that reducing cortical inhibition can unmask silent memories," said Barron. "This result is consistent with a balancing mechanism — the increase in excitation seen in learning and memory formation, when excitatory connections are strengthened, appears to be balanced out by a strengthening of inhibitory connections.”
While these findings are nothing short of intriguing, it’s important to keep in mind that the study sample was small, so further research will need to assess the mechanisms of antimemories on a larger, deeper scale.
However, as researchers continue to investigate these exact-opposite memory patterns in our brains, our understanding of neuroscience may be transformed in the years to come.