Neurobiologists at UC Irvine (UCI) have succeeded in creating new memories in the brains of rats. The same process should allow scientists to create memories in human (and other mammalian) brains, too. The UCI neurobiologists say that this is the first evidence that memories can be created by directly altered neurons in the cerebral cortex.

To create the memory, the researchers played a series of test tones to the rodent test subjects. When a specific tone played, the researchers stimulated the nucleus basalis, releasing acetylcholine (ACh). This jolt of ACh then causes the cerebral cortex to turn that specific tone into a memory. Later, when the rodents are played the same tone, their respiration spiked, showing they recognized the tone. The other tones, which weren’t subjected to a spike in ACh, did not cause the same reaction.

The nucleus basalis is thought to play a fundamental role in the formation of new memories, which this new study seems to confirm. Importantly, in patients with Parkinson’s or Alzheimer’s disease, and perhaps other memory disorders, the nucleus basalis degenerates, seemingly hindering the formation of new memories. Basically, as far as the researchers can tell, the release of ACh soon after some kind of stimulus (auditory, olfactory, visual, etc.) increases the number of brain cells that will respond to future occurrences of that stimulus. The more brain cells that are tuned to that stimulus, the stronger the memory. In this case, by releasing ACh just after a specific tone, a large block of neurons in the auditory cortex are tuned to that tone (see diagram above).

There are far-reaching exciting and ethical repercussions from this discovery. On the one hand, with some kind of brain stimulation implant, it might be possible to cure or alleviate the symptoms of Parkinson’s or Alzheimer’s. On the other, this means we now have the knowhow to implant memories into the brains of humans and other mammals — and by association, it probably isn’t too hard to delete specific memories as well. The concepts introduced by such books/movies as Matrix, Total Recall, and Eternal Sunshine of the Spotless Mind now seem scarily close to reality.

The good news is that we’re still a long way away from such therapeutic or destructive use-cases. It will require years of medical testing before you can walk into a clinic and ask to have a memories created or ablated — at least legally, anyway.

Now read: MIT discovers the location of memories: Individual neurons

Research paper: doi: 10.1523/​JNEUROSCI.2430-13.2013