But the leap to the human brain is so enormous that one of the scientists who has participated in planning sessions, the neuroscientist Terry Sejnowski from the Salk Institute, has called the challenge “the million neuron march.”

While the researchers have proposed a wide range of technologies that might be applied to the problems, many of them are still prototypes or speculative. Some of them, like nano-robots being designed at places like the Wyss Institute laboratory at Harvard, seem like they are straight from “Fantastic Voyage,” the 1966 movie that imagined the ability to shrink submarines and humans — specifically, Raquel Welch — for journeys through the human body.

Moreover, many technologies now used to sample human brain activity at high resolution require opening the skull, dramatically restricting what is possible. Progress is being made using those available techniques, but only at a basic level.

Still, last week in the journal Nature a group of neurosurgeons at the University of California, San Francisco, reported significant new insights into mechanisms of the language function of the human brain. That research, which was conducted with permission from three people who had severe epileptic seizures, involved installing a dense sensor mesh of electrodes on the surface of their brains. The 264 electrodes each sampled from an area that might encompass as many as millions of neurons, according to Dr. Edward F. Chang, a neurosurgeon who led the team.

Although the sensor’s resolution was crude, it was four times more powerful than what has been used until now. It revealed how the speech centers in the human cortex control the larynx, tongue, jaw, lips and face, all of which are involved in making the sounds that constitute human speech.

“I don’t think this was a major technological innovation,” Dr. Chang said. “But it demonstrates the power of even incremental advances, and shows how they can have a major impact on what we can understand.”

The goal of the University of California group is ultimately to gain enough understanding of the speech mechanism in the brain to be able to develop sophisticated prosthetics, making it possible for victims of paralysis or stroke to speak.