Cellular Pathways during Memory Formation | Molecular mechanism of Long Term Memory

This image shows neurons in the CA3 region of the hippocampus, which is important for memory encoding and retrieval. Nuclei of the CA3 ne...

This image shows neurons in the CA3 region of the hippocampus, which is important for memory encoding and retrieval. Nuclei of the CA3 neurons are labeled in green and their dendrites in red, and the smaller specks of green above represent axons projecting to the CA3 neurons from the dentate gyrus.

MIT neuroscientists have uncovered a cellular pathway that allows specific synapses to become stronger during memory formation. The findings provide the first glimpse of the molecular mechanism by which long-term memories are encoded in a region of the hippocampus called CA3.

The researchers found that a protein called Npas4, previously identified as a master controller of gene expression triggered by neuronal activity, controls the strength of connections between neurons in the CA3 and those in another part of the hippocampus called the dentate gyrus. Without Npas4, long-term memories cannot form.

"Our study identifies an experience-dependent synaptic mechanism for memory encoding in CA3, and provides the first evidence for a molecular pathway that selectively controls it," says Yingxi Lin, an associate professor of brain and cognitive sciences and a member of MIT's McGovern Institute for Brain Research.