For their experiment, the experts used genetically modified mice so that when their neurons were activated, they would glow with green fluorescence. In addition, these neurons expressed a protein that allowed to deactivate nerve cells with light. Thus, they discovered which neurons were activated in the cerebral cortex and the hippocampus, since both coordinate the recovery of episodic memories, when the mice learned and recovered memories and, on the other hand, deactivate those neurons with light by means of a fiber optic cable.
Thanks to the green fluorescence, the scientists showed that they could specifically identify the cells that participate in learning and that these were reactivated when the recovery of what was learned was necessary. In the same way, "turning off" those nerve cells of the hippocampus with light, they got the mice to lose that memory. This hypothesis was confirmed after trying to deactivate other cells of the hippocampus different from those involved in learning, and verifying that the memories were not affected in this case.
As explained in the journal Neuron Kazumasa Tanaka and Brian Wiltgen, leaders of the study, "this empirically demonstrates for the first time that the cerebral cortex can not store and recover memories by itself, but needs the help of the hippocampus."
