Scientists achieve the “impossible” with biggest brain map ever

For decades, scientists have struggled to make sense of the brain due to its mind-boggling complexity.

In fact, Nobel Prize-winning biologist Francis Crick (of Watson and Crick fame) concluded in 1979 that the anatomy and activity in just a single cubic millimeter of brain matter—as big as a grain of sand—would forever exceed humanity’s understanding.

But the purported impossible has now been achieved, according to a new study published in Nature. It details how researchers recorded the cellular activity in a cubic millimeter of a mouse’s brain then used it to create the largest brain map to date, containing 523 million neural connections.

The brain, explained

The scientists’ process involved three main steps:

1. Taking a mouse genetically engineered to make neurons glow when they’re active, then treating it like a stoner with unlimited internet access—aka showing it YouTube clips of sci-fi movies, sports, animation, and nature—to record the reactions in its brain’s visual cortex.
2. Analyzing this grain-of-sand-sized visual cortex. This involved shaving it into 25,000+ layers and taking ~100 million high-resolution images of the microscopic wiring contained within.
3. Using AI tools to trace the entire wiring and paint each individual wire a different color. Researchers estimated the microscopic wiring contained in the cubic millimeter would measure 3+ miles long if laid out.

The impact: Scientists say the new map will allow them to study brain function in extraordinary detail, potentially revealing insights into hard-to-treat brain disorders and how complex traits like consciousness arise.