Although immune cells are largely locked out of the central nervous system, they can still keep a close watch on cellular trash being removed from the brain to scan for infection or injury. And conversely, immune cells also send signals of their own that influence brain function.
The microbial communities living in the gastrointestinal tracts of newborn babies have changed a lot in the past century, with beneficial Bifidobacterium species becoming far less prominent, especially among formula-fed infants. Understanding why that is has helped researchers develop probiotics that can restore a more historic microbiome.
In the mid-1990s, more than 40 gray wolves were released into Yellowstone National Park, and in the years and decades that followed, researchers attributed the ecosystem’s rejuvenation to the reintroduction of the apex predators. But the nature of the wolves’ influence is still debated. Now, efforts are ongoing to repeat the experiment and try to get to the bottom of how predators affect their environments.
Mouse neurons associated with a new memory can be permanently altered by researchers to give them control over their activity. Specifically, scientists typically add channelrhodopsin to neurons in a memory network such that they can activate them with blue light. In this way, animals can be prompted to recall something or even to remember an experience that never happened.
In many bird species, males are more brightly colored than females. In some finches, the gene BCO2, which encodes a carotenoid-destroying enzyme, appears to explain this sexual dimorphism, often being expressed in female feathers but not male feathers.
As the Earth’s atmosphere warms, Arctic ice is melting and sea levels are rising. This pushes salt water further into terrestrial ecosystems, killing forests and threatening farms. The result is a migration of wetland tree species into deciduous and pine forests further inland.
Just before the turn of the century, scientists confirmed that adult human brains do in fact generate new neurons. Two decades later, the field of neurogenesis research is beginning to understand how those new neurons integrate into existing neural networks to influence learning and memory.