Knowledge is power.
Building up memories and learning from past experience is the best tool that humans and animals have to adapt to the constantly changing world around them. Neuroscientists are seeking to understand what the mechanisms behind learning and memory are, and how this can answer questions about the way we think.
Consider two recent blockbuster films. In 2000, Memento gave an insight into a world of lost memories. In 2010, Inception planted the idea that you could plant ideas into other people’s minds. You are probably familiar with these films but what you may not know is that neuroscientists have recently come tantalisingly close to being able to incept and erase memories in reality.
Trying to find evidence for a link between cells firing in the brain and being able to say what you had for lunch yesterday is unsurprisingly a difficult task. Scientists have been working for around 40 years on one theory, hoping to find an explanation for how learning and memory works. Its name- Synaptic Plasticity.
This theory states that when brain cells that ‘synapse’ or connect onto each other are repeatedly activated at the same time then a change will take place at this synapse which means that it will become easier for these cells to fire together. This means that the more often something happens to you, the more a certain few cells will fire together and consequently you will be able to remember that event more easily.
In order to prove that this synaptic plasticity is really causing learning, scientists have created ingenious ways to study it under different conditions. Using a variety of techniques to interfere with synaptic plasticity they have been able to cause a surprising range of effects on an animal’s normal learning ability. Some compounds successfully stop animals from learning, whilst some improve their performance in learning and some genetically modified animals are born without proper learning abilities. One chemical known as ZIP can even erase the memories an animal has already formed in Memento-like fashion.
In 2013 a group at MIT were able to detect what cells were active when a rat was in a particular environment. Using a technique called optogenetics they could reactive these cells in a second environment by shining light onto them. Whilst the memory of the first environment was being reactivated the rat received an electrical shock. Incredibly, when the animal was placed back in the first environment it recoiled in fear.
The animal falsely associated this environment with the shock- a false memory had been incepted.
Synaptic plasticity certainly seems to have an effect on learning and memory but is not necessarily its only contributor. The implications of utilising the mechanisms of synaptic plasticity seem endless for treating diseases which affect memory such as Alzheimer’s. Although we are a long way off from human treatments, synaptic plasticity holds great potential for the future.