MIT News (August 17, 2017): How We Recall the Past

August 18, 2017

When we have a new experience, the memory of that event is stored in a neural circuit that connects several parts of the hippocampus and other brain structures. Each cluster of neurons may store different aspects of the memory, such as the location where the event occurred or the emotions associated with it.

Neuroscientists who study memory have long believed that when we recall these memories, our brains turn on the same hippocampal circuit that was activated when the memory was originally formed. However, MIT neuroscientists have now shown, for the first time, that recalling a memory requires a “detour” circuit that branches off from the original memory circuit.

“This study addresses one of the most fundamental questions in brain research - namely how episodic memories are formed and retrieved - and provides evidence for an unexpected answer: differential circuits for retrieval and formation,” says Susumu Tonegawa, the Picower Professor of Biology and Neuroscience, the director of the RIKEN-MIT Center for Neural Circuit Genetics at the Picower Institute for Learning and Memory, and the study’s senior author.

This distinct recall circuit has never been seen before in a vertebrate animal, although a study published last year found a similar recall circuit in the worm Caenorhabditis elegans.