Aug. 22 (UPI) -- For decades, scientists have used experimental drugs to cure mice of brain disorders like Alzheimer's disease, glioblastoma and depression. But on human brains, these treatments often don't work.
Now, researchers have pinpointed specific differences in the largely similar brain structures of humans and mice, according to a study published Thursday in Nature.
The discovery of these differences could open a gateway to understanding why so many treatments that work with mice do not translate to good treatments for humans.
"Just as we can use our genes to build our family trees or find long-lost relatives with services like ancestry.com or 23andme, we're letting the genes tell us the story of our brains and their evolution," said Ed Lein, a researcher at the Allen Institute for Brain Science and study senior author, in a news release. "And in the same way that police were able to use information in those genetic databases to track down the Golden State Killer, this new high-resolution view of our brains provides a baseline to find the cells that go wrong in disease."
The researchers took nearly 16,000 isolated cells from the brains of deceased people and surgical tissue from epileptics. The cells originated from the middle temporal gyrus area of the human cerebral cortex, which controls emotion, memory, thought and other executive functions.
They also analyzed cells from the same area of mouse brains.
In all, the humans had 75 distinct cell types that matched up with the mice. But within those cells, the expression in 18 percent of the genes differed by at least 10-fold.
For example, the gene expression varies in the neurotransmitter glutamate receptors of mice and human brain neurons. Neurons use neurotransmitter to communicate gene expressions.
"The bottom line is there are great similarities and differences between our brain and that of the mouse," said Christof Koch, the chief scientist at the Allen Institute for Brain Science and study author. "One of these tells us that there is great evolutionary continuity, and the other tells us that we are unique. If you want to cure human brain diseases, you have to understand the uniqueness of the human brain."