Scientists unveil the most detailed and precise map of the mouse motor cortex to date
The brain's motor cortex plans, controls and executes voluntary muscle movements. Whether you're playing catch, writing your name or chewing food, it all points back to this region and its connections to other parts of the brain. Yet despite extensive study, scientists still haven't created a detailed map of how the mouse motor cortex is internally organized. Most brain atlases have divided it…
A team of scientists from the University of Basel, Friedrich Miescher Institute for Biomedical Research, and the Allen Institute have unveiled a highly detailed map of the mouse motor cortex. This brain region is responsible for planning, controlling, and executing voluntary muscle movements. Despite previous studies, no comprehensive map of the mouse motor cortex's internal organization existed until now.
The new research, published in Cell, divides the motor cortex into 16 distinct subregions, each with unique patterns of connections.
The researchers studied 547 experiments that tracked nerve signals traveling from the motor cortex to other brain areas, focusing on where each section sends its messages. They classified the areas into three rows and two main groups based on their signal similarities. The study also confirmed their findings through two additional methods: tracing individual neurons and examining the types of brain cells present. All three methods led to the same 16-subregion structure.
Interestingly, the primary and secondary motor cortices work together when sending signals to the brainstem and spinal cord, contradicting previous assumptions that they followed a strict hierarchy. The most significant discovery is the high precision with which the motor cortical modules interact with output regions, sharing the same wiring logic for communication with the rest of the cortex.
Understanding the precise wiring of the brain is crucial for developing effective treatments for brain diseases. The motor cortex is affected by conditions like amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). By identifying vulnerable subregions and tracking disease progression through connected areas, scientists can now better understand why certain cells are targeted in these diseases.
The researchers used the Allen Institute's Mouse Brain Atlas, which contains anatomical databases and workflows, to conduct their high-precision work. The detailed map is now available to the research community through an online tool called BrainGlobe, enabling scientists to work from a unified reference point. This development will accelerate progress in the field by providing a valuable and precise blueprint of motor cortex organization.
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