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Curing vexing diseases requires navigating the brain, USC scientists have created the most detailed atlas of the brain’s memory bank. Cartographers of the cranium, a USC research team has illustrated the internal circuitry of the hippocampus in detail that would make the great ancient mapmaker, Ptolemy, proud.
Using fluorescent tracers and 3-D animation, the scientists show structures, nerve connections and functions in vivid detail. “Like a new atlas, we’ve constructed the most detailed diagram of the hippocampus to date,” said Michael S. Bienkowski, lead author of the study and a researcher at the USC Institute for Neuroimaging and Informatics in the Keck School of Medicine of USC. “With a better map, we can see each region and how it functions. A better map is a resource scientists can use to understand the hippocampus and how its degeneration leads to diseases.”
The human hippocampus sits at the base of the brain and it’s shaped like a seahorse. It stores memories, regulates emotions and guides navigation by spatial processing. It’s the first part of the brain impaired by Alzheimer’s and hippocampus degeneration can cause epilepsy and other diseases. In this case, scientists worked on a mouse brain because it’s organized similar to a human brain. Scientists can use the new map of the hippocampus to deliver genetically-targeted drugs to specific neurons with fewer side effects, USC professor of neurology and director of the USC Center for Integrated Connectomics (CIC).
The work is part of the Mouse Connectome Project, a USC-led effort that collects lots of data about neural connections in the brain and shares it publicly with researchers in more than 100 countries. Disconnections in the brain underlie Huntington’s disease, Parkinson’s disease, Alzheimer’s disease, autism spectrum disorders and many other illnesses.
Scientists have known the basic four-part architecture of the hippocampus for a long time. What’s different now is the USC scientists can show its sub-regions and how nerve cells interact across the structure. It’s a night-and-day difference, akin to seeing transmission lines and power poles slung across a city by day compared to fully illuminated at night. This new visualization traces neural pathways and connections in remarkable detail using fluorescent dyes as tracers that reveal cells, neuron junctions and connections to the rest of the brain.
“It totally changes our understanding by combining a wiring diagram with gene expression of the mouse hippocampus. We see it doing different things, and this gives us a new way to understand how the whole thing works together. According to the National Institute on Aging, alzheimer’s disease is the sixth leading cause of death for older people.