When you remember a particular experience, that memory has three critical elements — what, when, and where. MIT neuroscientists have now identified a brain circuit that processes the “when” and “where” components of memory.
This circuit, which connects the hippocampus and a region of the cortex known as entorhinal cortex, separates location and timing into two streams of information. The researchers also identified two populations of neurons in the entorhinal cortex that convey this information, dubbed “ocean cells” and “island cells.”
Previous models of memory had suggested that the hippocampus, a brain structure critical for memory formation, separates timing and context information. However, the new study shows that this information is split even before it reaches the hippocampus.
“It suggests that there is a dichotomy of function upstream of the hippocampus,” says Chen Sun, an MIT graduate student in brain and cognitive sciences and one of the lead authors of the paper, which appears in the Sept. 23 issue of Neuron. “There is one pathway that feeds temporal information into the hippocampus, and another that feeds contextual representations to the hippocampus.” Read more