Time course of memory relocation revealed

The time-dependent role of the hippocampus in memory storage has been revealed through new research led by UCL and the Massachusetts Institute of Technology (MIT). The paper, published in PLOS ONE , investigated the dynamic nature of memory storage in the brain - studying the role of the hippocampus in the storage of contextual memories in rodents. The hippocampus, a brain structure within the medial temporal lobe in humans, is necessary for storing recent experiences into memory. However, the hippocampus only acts as a temporary storage for memories, as older memories are eventually transferred to other parts of the brain for long-term storage. To observe this process more precisely, researchers used a molecular-genetic tool (DREADDs: Designer Receptor Exclusively Activated by Designer Drugs), to remotely and reversibly inactivate the hippocampus at multiple time points after the initial formation of a memory, and study the time-dependent involvement of the hippocampus in memory storage. The researchers, led by Dr Daniel Bendor (UCL Experimental Psychology) and Dr Carmen Varela (MIT), found that after 4-7 weeks contextual fear memories in rodents no longer require the hippocampus, an indication that the memory is transferred to extra-hippocampal brain regions such as the neocortex. These results support earlier research demonstrating that hippocampal lesions disrupt recent memories but not older, more remote memories.