By Laura Boness
Memories make us who we are and allow us to recall the ‘who, what, when, where and why’ of our everyday lives. And every time we create a new memory, it causes a change in our brains.
The brain is made up of 100 billion nerve cells, called neurons, which gather and transmit information via electrochemical signals. They are connected to each other through structures called synapses, but if a memory is formed and stored the pattern of the synapses is believed to change.
“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,” says Dr Don Arnold from the University of Southern California.
Arnold and his colleagues have found a way to see exactly how the pattern changes. During their study they attached fluorescent markers onto the synpases, using microscopic probes consisting of antibody-like proteins that would bind to specific synaptic proteins.
In order to see what was happening, they attached the probes to a green fluorescent protein that can be isolated from jellyfish. Because they are proteins, the genes encoding them can be put into brain cells in living animals, causing the cells themselves to manufacture the probes.
“These probes were created in such a way that the DNA encoding the probe is isolated,” says Arnold. “Once you have the DNA that encodes the probe it is easy to fuse it to DNA encoding a fluorescent protein.”
When the fused gene was placed in a neuron, the neuron translates it and creates a protein that sticks to the synaptic proteins and to a fluorescent protein – all without affecting the neuron itself. The scientists could then put them in place and watch the synapses changing as new memories form in the brains of mice.
The synapses appeared as bright spots along the dendrites (the part of a neuron that transmits the signals). As the brain processes the new information, those bright spots change, indicating how the synaptic structures in the brain have been changed by the new data.
Proteins are large molecules that are made up of long strings of amino acids. They help build, repair and replace most of the tissues in your body, such as the immune system, organs and muscles.