Everything we thought we knew about memory is wrong

For many people, memories are deeply personal; locked inside our brains. Now scientists at the University of California, Los Angeles are challenging that notion. They've figured out a way to transfer memory between organisms—specifically, snails.

David Glanzman, a professor of neurobiology at UCLA and the author of a new study, achieved this by extracting RNA from snails that were conditioned to expect shocks anytime their tails were touched and injected it into snails that had not experienced shocks. The memory of the trauma was transferred from one snail to another.

RNA is an information carrying molecule like DNA, but more temporary. In this study, the scientists were looking at a particular subtype of RNA that doesn't just carry messages for DNA, but also decides how to use the DNA. This subtype effectively changes the gene expression so that a memory is programmed right into how the DNA is used.

Approach to memory 'has to be revised'

Until now, scientists believed memories lived between brain cells, called neurons, as a pattern of connections. However, this new research suggests that a single cell or neuron can contain memory.

The model of long-term memory that's the dominant one in the field has to be revised.- David Glanzman

"The model of long-term memory that's the dominant one in the field has to be revised," said Glanzman. "Because it's impossible to explain our results—if they're right—in terms of the synaptic model."

Glanzman's results show a different kind of cellular reprogramming that happens when the brain forms memories, which is also likely true of humans and could help scientists in the research for conditions like Alzheimer's, PTSD and other memory disorders.

Humans have an infinitely more complex brain and more possible connections. This type of snail (the Aplysia californica or sea snail) only has about 20,000 neurons, while a human brain has an estimated 100 billion. However, scientists use these snails because their nervous system is simple and therefore much easier to study than humans. And when you
research basic cell biology, the cell of a snail is not that much different than the cell of the human brain.

Memory researchers are skeptical

This result challenges the dogma of all memory science and scientists are debating it within the field. While this experiment seems to have successfully transferred a memory, it did not transfer a complex memory. Instead, Glanzman transferred a type of genetic reprogramming that happens with a trained response to one stimulus. It's a memory in its simplest form.

The science is solid and the effect is real, but how RNA is able to do this and what this all means remains to be determined. Viewing a memory as a cellular change—one that happens within the cell, not between cells—is a steep change in the field and there is understandable resistance to throwing out decades of work and thousands of papers.