Scientists have long pondered the question of how and where the brain stores episodic memories, complex associations of objects, space and time. MIT research led by Susumu Tonegawa reveals new details of the location of both actual memories and artificially induced false memories within the hippocampus of a mouse brain. The image above shows the mouse's memory traces in red. Not surprisingly, the brain demonstrated exactly the same neural mechanisms for storage of real and false memories. So how are the memory associations made?
These associations are encoded by chemical and physical changes in neurons, as well as by modifications to the connections between the neurons. Compared to most studies that treat the brain as a black box while trying to access it from the outside in, this is like we are trying to study the brain from the inside out. The technology we developed for this study allows us to fine-dissect and even potentially tinker with the memory process by directly controlling the brain cells.
It has been suspected that memories were located in the temporal lobe since the 1940s when researchers discovered that electrical stimulation of the region caused patients to spontaneously recall past events. But proof of this theory had to wait until it was possible to demonstrate that the activation of specific hippocampal cells was sufficient to produce memories. The MIT researchers are using a new technique called Optogenetics to do just that. Understanding how biological memory works may lead to new breakthroughs in machine learning. Unfortunately the MIT paper is pay-walled but the abstract is available.