A few people have sent this my way and asked about it:
In a paper published Monday in the journal eNeuro, scientists at the University of California-Los Angeles reported that when they transferred molecules from the brain cells of trained snails to untrained snails, the animals behaved as if they remembered the trained snails’ experiences…
In experiments by Dr. Glanzman and colleagues, when these snails get a little electric shock, they briefly retract their frilly siphons, which they use for expelling waste. A snail that has been shocked before, however, retracts its siphon for much longer than a new snail recruit.
To understand what was happening in their snails, the researchers first extracted all the RNA from the brain cells of trained snails, and injected it into new snails. To their surprise, the new snails kept their siphons wrapped up much longer after a shock, almost as if they’d been trained.
Next, the researchers took the brain cells of trained snails and untrained snails and grew them in the lab. They bathed the untrained neurons in RNA from trained cells, then gave them a shock, and saw that they fired in the same way that trained neurons do. The memory of the trained cells appeared to have been transferred to the untrained ones.
The full paper is here.
Long and short of this is that there is a particular reflex (memory) that changes when they have experienced a lot of shocks. How memory is encoded is a bit debated but one strongly-supported mechanism (especially in these snails) is that there are changes in the amount of particular proteins that are expressed in some neurons. These proteins might make more of one channel or receptor that makes it more or less likely to respond to signals from other neurons. So for instance, when a snail receives its first shock a neuron responds and it withdraws its gills. Over time, each shock builds up more proteins that make the neuron respond more and more. These proteins are built up by the amount of RNA (the “blueprint” for the proteins, if you will) that are located in the vicinity of the neuron that can receive this information. There are a lot of sophisticated mechanisms that determine how and where these RNAs are built and then shipped off to the place in the neuron where they can be of the most use.
This new paper shows that in these snails, you can just dump the RNA on these neurons from someone else and the RNA has already encoded something about the type of protein it will produce. This is not going to work in most situations (I think?) so it is surprising and cool that it does here! But hopefully you can begin to see what is happening and how the memory is transferring. The RNA is now in the cell, it is now marked in a way that will lead it to produce some protein that will change how the cell responds to input, etc, etc.
One of the people who asked me about this asked specifically in relation to AI. Could this be used as a new method of training in Deep Networks somehow? The closest analogy I can think of is if you have two networks with the same architecture that have been trained in the same way (this is evolution). Then you train a little more, maybe on new stimuli or maybe on a new task, or maybe you are doing reinforcement learning and you have a network that predicts a different action-value pair. Now the analogy would be if you chose a few units (neurons) and directly copied the weights from the first network into the second network. Would this work? Would this be useful? I doubt it, but maybe? But see this interesting paper on knowledge distillation that was pointed to me by John O’Malia.