For decades Henry Markram has dreamed of reverse engineering the human brain. In 1994, as a postdoctoral researcher then at the Max Planck Institute for Medical Research in Heidelberg, Germany, he became the first scientist to “patch” two living neurons simultaneously—to apply microscopic pipettes to freshly harvested rat neurons to measure the electrical signals fired between them. The work demonstrated the process by which synapses are strengthened and weakened, making it possible to study and model how the brain learns. His work landed him a position as senior scientist at the prestigious Weizmann Institute of Science in Rehovot, Israel, and by the time he was promoted to professor in 1998, he was one of the most esteemed researchers in the field.

Then he began to get frustrated. Although researchers worldwide were publishing tens of thousands of neuroscience studies every year, neither our understanding of basic brain functions nor our ability to treat brain disorders seemed to be progressing much. Markram's consternation was also deeply personal. While he was still in Germany, his son Kai had been diagnosed with autism. As he told The Guardian in 2013, he wanted “to be able to step inside a simulation of my son's brain and see the world as he sees it.” The only way to do that, he reasoned, was to go beyond individual experiments with behaviors, diseases and brain anatomy and instead model the circuitry of the entire human brain.

In a 2009 TED talk, he first presented to the general public his vision of mathematically simulating the brain's 86 billion neurons and 100 trillion synapses on a supercomputer. “We can do it within 10 years,” he promised the audience, suggesting that such a mathematical model might even be capable of consciousness. After those 10 years, Markram told the audience, “we will send … a hologram to talk to you.” In various talks, interviews and articles, he suggested that a mathematical brain model would deliver such fundamental breakthroughs as simulation-driven drug discovery, the replacement of certain kinds of animal experiments and a better understanding of disorders such as Alzheimer's. As if that were not enough, the simulated brain would also spin off technology for building new and faster computers and create robots with cognitive skills and possibly intelligence. Plenty of neuroscientists were skeptical, but Markram had many supporters. His vision seemed vindicated in January 2013, when the European Union awarded him $1.3 billion, spread over 10 years, to build his simulated brain.