New Research Demonstrates How the Brain Forms Memory

Rebecca Lewis June 21, 2013

A team of scientists from the University of Southern California devised a way to see how the brain creates and stores memory. The technique allowed them to see live excitatory and inhibitory synapses and how they change as new memories are formed.

The team used engineered microscopic probes that light up synapses in a living neuron in real time by attaching fluorescent markers onto synaptic proteins in the brain, without harming the functionality of the neurons. The synapses appear as bright spots along the dendrites – the branches of a neuron that transmit electrochemical signals. As the brain processes new information, the synaptic structures in the brain are altered, which is indicated by the change in the bright spots.

"When you make a memory or learn something, there’s a physical change in the brain. It turns out that the thing that gets changed is the distribution of synaptic connections," said Don Arnold, one of the lead authors and an associate professor of molecular and computational biology at USC.

Because the probes behave like antibodies, but binding more tightly inside the cell, the researchers had to use a technique called ‘mRNA display’ developed by co-author Richard Roberts and Nobel laureate Jack Szostak.

According to Roberts, the mRNA display allowed them to search through more than a trillion different potential proteins simultaneously and find the protein that binds the target the best.

The probes created, called ‘FingRs’, were attached to the green fluorescent protein (GFP) that turns bright green when exposed to blue light. Because FingRs are protein, the genes encoding them can be put into the brain cells of living animals, triggering the brain cells to manufacture probes themselves. The revolutionary approach designed by the USC researchers included a system that cuts off the amount of FingR-GFP generated once the target protein is labelled. This eliminated the background fluorescence and led to a sharper and clearer image of the brain synapses.

The current study was initiated to better understand how humans think, learn, and remember, and how exactly the brain works. The findings were published in the journal Neuron.

Source of this article:

Recombinant Probes for Visualizing Endogenous Synaptic Proteins in Living Neurons