How do we store memories?
Scientists have created a new technology to watch memories forming!
Oscar Wilde called memory "the diary that we all carry about with us," and scientists are keen to see where and how this diary is written.
There are about 100 billion nerve cells in the human brain and about 1000 trillion connections between them. In just one cubic millimetre of the average person's brain tissue there are more than 1 million nerve cells (106) and 1 billion (109) connections. It's thought that these connections are the key to storing memories.
New connections form as we experience new things. The connections comprise bulbous clusters of proteins that help transfer signals from one nerve cell to its neighbour. And it's this circuitry that allows us to learn, remember, process information, speak and move.
Technological advances over the last couple of decades has allowed us to peer into living mouse brains, for instance by using the green fluorescent protein (GFP) that makes jellyfish glow. Expressed in the mouse brain cells, it can be used to watch how neurones change as experimental animals carry out learning and memory tasks.
But we've not been able to look at the living protein bulbous cluster movements in the connections before. Now, Don Arnold and Richard Roberts at the University Southern California have published, in Neuron, a new microscopic probe technique to illuminate the proteins that form the connections between nerve cells, as they form.
Using an antibody that can get inside cells, coupled with a technique called mRNA display, the California duo were able to precisely localise a GFP signal just to one protein involved in forming neuronal connections.
The probes work in nerve cells and brain slices in the dish. The next step is to put them in the brains of living mice and image through the brain using a technique called two-photon microscopy to study what's happening to connection proteins during sleep, since sleep is known to play a major role in memory formation and consolidation, and as a mouse learns a new task, like recalling the locations of food treats in a maze...