Scientists have created an inventory of cells in the brain’s motion control center – the first step toward understanding the brain’s circuits of nearly 90 billion neurons that underlie our movements, thoughts and feelings.
why it matters: Cells do not work in isolation. Determining the circuits connecting neurons could help researchers understand processes in the brain and what happens when they stray from disease.
- Ultimately, the hope is that these brain maps will provide new targets for drugs to treat Alzheimer’s and Parkinson’s diseases, as well as for neuropsychiatric diseases where there is an aberration in the way cells communicate, according to NIH’s Brain (via Brain Research) John Nagai, director of Brain Research). Advancing Innovative Neurotechnologies) initiative, which coordinated the effort to create a cell census.
- Ngai and others envision treatments that act on specific cell circuits that lead to disease, rather than on every cell. Such targeted treatments can help reduce the side effects seen with some medications.
running news: Hundreds of researchers collaborated to define and catalog cells in the primary motor cortex region of the brains of rats, marmosets, and humans. report good This week 17 papers in the journal Nature.
- The goal of the research is to produce a “parts list for the brain,” says Hongkui Zeng, director of the Allen Institute for Brain Science and co-author of some of the papers.
- There are about 170 billion cells in the brain (about half are neurons and half are other cells) with trillions of connections between them. Some cells may have similar sizes but differ in their functions and locations.
- Researchers have struggled to group the cells into separate groups, which will help them figure out what circuits they form and how they function.
What did they do: The researchers combined information about genes being expressed in cells (their transcripts), their size, electrical activity and other properties, and found more than 100 types of cells in the human motor cortex.
- Comparing RNA information with cells’ size, electrical activity and other properties, the researchers found that RNA patterns could be used to predict the type of cell.
- They then determined where the sections of cells were located within the motor cortex, which is involved in coordinating movement.
- When cells in the mouse motor cortex were compared to those of marmosets and humans, they found that there are some important differences between how the cells are organized. But similar cells were present in the three species, suggesting that those cells are central to circuits more broadly in mammals and pointing to potential animal models for the study of diseases.
yes but: The map of the entire human brain circuitry is still in the future.
- “Getting a parts list is really only the first step,” Zeng says. “We don’t know what the cell types do yet and how they are related to each other.”
- There is also the issue of how cell circuits differ between individuals and how they change, whether over time or dramatically during development or disease, she says.
- And the size of the human brain is huge: it is 200 times larger than the brain of a rat. “It can take two years to do the whole mouse brain,” Zeng says, adding that equipment is needed to speed up the process. “We don’t want to take 1,000 years for the human brain to do it.”
big picture: Research published this week is one effort among many pursuing a grand goal map every cell in human body.
- It centers around a new frontier in biology – the study of where different cells are located in tissues and how they interact and influence each other.
- This spatial information gives scientists access to the “ground truth” of biology, says Ben Hindson, chief scientific officer of 10X Genomics, a company that sells tools to analyze the properties of cells within tissues.
- Spatial biology is being used to study cancer diagnosis, the immune response to cancer treatments, regenerative medicine and more, says Evan Keller, a cancer biologist at the University of Michigan who directs the Single Cell Spatial Analysis Program at the university. We do.
- “It’s going to help us clinically in terms of diagnosis, prognosis and precision medicine,” he predicts.