He went to the Weizmann Institute of Science in Israel to earn a Ph.D., followed by a stint at the National Institutes of Health in the United States on a Fulbright scholarship. That work led to a position with the Nobel Prize-winning neurophysiologist Bert Sakmann at the Max Planck Institute in Germany.

At Dr. Sakmann’s lab, Dr. Markram made his most famous discovery.

He was pondering how the brain learns cause and effect. He set up an experiment to record the electrical activity from two connected neurons in a slice from a rat’s brain, and discovered that the neurons required a precise sequence of voltage spikes to change the strength of their connections. He speculated that the mechanism might be at the root of our notion of causality.

That work has now been cited thousands of times. Yet as Dr. Markram’s reputation grew, so did his impatience.

Neurons are organized into interconnected circuits that can number in the millions. Dr. Markram realized that to make real progress linking neurons to behavior, experimenting on two neurons at a time “just wasn’t enough.”

In his first faculty position, at the Weizmann Institute, he set up a wildly ambitious new experimental rig that could record data not just from 2 neurons in a rat’s brain but also from 12.

“His rig made NASA look tame,” recalled Dr. Markram’s postdoctoral adviser at the N.I.H., Elise F. Stanley, who visited him at the Weizmann in 1995. “There was so much equipment that you couldn’t even see the brain tissue.”

Soon Dr. Markram would learn that his son, Kai, had autism. “You know how powerless you feel,” he said. “You have this child with autism, and you, even as a neuroscientist, really don’t know what to do.”