Even cooler, the UC Davis researchers managed to erase specific memories in the mice whose brains they toyed with

Oct 10, 2014 19:03 GMT  ·  By

In a paper in the journal Neuron, scientists detail the use of light to give laboratory mice amnesia. More precisely, the researchers claim that light enabled them to erase specific memories in the rodents whose brains they toyed with.

The UC Davis specialists behind this research project say that, as part of their investigation, they first created genetically engineered mice whose nerve cells appeared fluorescent green and expressed a specific protein when activated.

They then placed the rodents in a special enclosure on several occasions and gave them a mild electric shock. Soon enough, the mice learned to fear this cage, and simply froze in place when inside it.

Having trained the rodents to expect being electrocuted when in the special enclosure, the scientists used light to switch off the nerve cells previously documented to be active both when the mice formed memories and when the animals were recalling things they had learned.

The process of deactivating nerve cells by shining light on neurons engineered to express a certain protein is known as optogenetics, the specialists explain in their paper documenting this series of experiments.

Once light was used to pull the plug on some of the rodents' neurons, the animals lost all memories of the electric shocks they had suffered. Hence, they no longer feared the cage or froze in place when put inside it.

The neurons that the scientists toyed with as part of this investigation were located in the mice's cerebral cortex and the hippocampus. It was discovered that the animals only lost their memory of the shocks when the cells in the hippocampus were deactivated.

This indicates that, as previously theorized, the cortex is in charge of processing information and enabling learning, whereas the hippocampus merely reproduces a certain pattern of activity in order to replay a past experience.

“The cortex can't do it alone, it needs input from the hippocampus. This has been a fundamental assumption in our field for a long time and Kazu’s [study leader Kazumasa Tanaka] data provides the first direct evidence that it is true,” researcher Brian Wiltgen said in a statement.