Scientists have created the largest brain map, or “connectome,” to date by studying a lab mouse that watched movies like “The Matrix” and “Star Wars.” The 3D atlas contains billions of brain cells and trillions of connections, providing new insights into how the brain functions.
Researchers mapped a portion of the mouse’s brain spanning just 1 cubic millimeter, roughly the size of a grain of sand. This small area has kilometers of wiring, making it an ideal subject for studying brain connections.
The team used advanced microscopes to capture brain cell anatomy and activity, then built the connectome using a machine learning algorithm that traced the brain cells and their extensions. The resulting map contains 200,000 cells and 523 million connections between neurons.
This dataset is three times larger than a connectome taken from part of a human brain and 40 times larger than one created for the fruit fly brain. However, it’s incomplete, with some brain cells missing, and contains “orphan” extensions that don’t appear to emanate from any cells.
The connectome revealed new information about how inhibitory neurons switch off firing in excitatory neurons, providing a breakthrough in understanding neural connections. The researchers also found that inhibitory cells originating from different areas can converge onto the same target cells located far away.
This study is a major boon for the neuroscience community, with other researchers now able to leverage the data for their own work. The findings could provide crucial insights into addressing neurological disorders where circuit dysfunction plays a role, such as Alzheimer’s disease and multiple sclerosis.
The team plans to build on this success by developing a connectome of the whole mouse brain in the coming decade, which could help researchers understand long-distance circuitry between different brain regions. However, funding uncertainty remains, with $278 million cut from the National Institutes of Health’s BRAIN Initiative last year.
Source: https://www.livescience.com/health/neuroscience/scientists-built-largest-brain-connectome-to-date-by-having-a-lab-mouse-watch-the-matrix-and-star-wars