#whengravityfails

The ability to send thoughts directly to another person’s brain is the stuff of science fiction. At least, it used to be.

In recent years, physicists and neuroscientists have developed an armory of tools that can sense certain kinds of thoughts and transmit information about them into other brains. That has made brain-to-brain communication a reality.

These tools include electroencephalograms (EEGs) that record electrical activity in the brain and transcranial magnetic stimulation (TMS), which can transmit information into the brain.

In 2015, Andrea Stocco and his colleagues at the University of Washington in Seattle used this gear to connect two people via a brain-to-brain interface. The people then played a 20 questions–type game.

An obvious next step is to allow several people to join such a conversation, and today Stocco and his colleagues announced they have achieved this using a world-first brain-to-brain network. The network, which they call BrainNet, allows a small group to play a collaborative Tetris-like game. “Our results raise the possibility of future brain-to-brain interfaces that enable cooperative problem-solving by humans using a ‘social network’ of connected brains,” they say.

The technology behind the network is relatively straightforward. EEGs measure the electrical activity of the brain. They consist of a number of electrodes placed on the skull that can pick up electrical activity in the brain.

A key idea is that people can change the signals their brain produces relatively easily. For example, brain signals can easily become entrained with external ones. So watching a light flashing at 15 hertz causes the brain to emit a strong electrical signal at the same frequency. Switching attention to a light flashing at 17 Hz changes the frequency of the brain signal in a way an EEG can spot relatively easily.

TMS manipulates brain activity by inducing electrical activity in specific brain areas. For example, a magnetic pulse focused onto the occipital cortex triggers the sensation of seeing a flash of light, known as a phosphene.

Together, these devices make it possible to send and receive signals directly to and from the brain. But nobody has created a network that allows group communication. Until now.

Stocco and his colleagues have created a network that allows three individuals to send and receive information directly to their brains. They say the network is easily scalable and limited only by the availability of EEG and TMS devices.

The proof-of-principle network connects three people: two senders and one person able to receive and transmit, all in separate rooms and unable to communicate conventionally. The group together has to solve a Tetris-like game in which a falling block has to be rotated so that it fits into a space at the bottom of the screen.

The two senders, wearing EEGs, can both see the full screen. The game is designed so the shape of the descending block fits in the bottom row either if it is rotated by 180 degrees or if it is not rotated. The senders have to decide which and broadcast the information to the third member of the group.

To do this, they vary the signal their brains produce. If the EEG picks up a 15 Hz signal from their brains, it moves a cursor toward the right-hand side of the screen. When the cursor reaches the right-hand side, the device sends a signal to the receiver to rotate the block.

The senders can control their brain signals by staring at LEDs on either side of the screen—one flashing at 15 Hz and the other at 17 Hz.

The receiver, attached to an EEG and a TMS, has a different task. The receiver can see only the top half of the Tetris screen, and so can see the block but not how it should be rotated. However, the receiver receives signals via the TMS from each sender, saying either “rotate” or “do not rotate.”

The signals consist of a single phosphene to indicate the block must be rotated or no flash of light to indicate that it should not be rotated. So the data rate is low—just one bit per interaction.

Having received data from both senders, the receiver performs the action. But crucially, the game allows for another round of interaction.

The senders can see the block falling and so can determine whether the receiver has made the right call and transmit the next course of action—either rotate or not—in another round of communication.

This allows the researchers to have some fun. In some of the trials they deliberately change the information from one sender to see if the receiver can determine whether to ignore it. That introduces an element of error often reflected in real social situations.

But the question they investigate is whether humans can work out what to do when the data rates are so low. It turns out humans, being social animals, can distinguish between the correct and false information using the brain-to-brain protocol alone.

That’s interesting work that paves the way for more complex networks. The team says the information travels across a bespoke network set up between three rooms in their labs. However, there is no reason why the network cannot be extended to the Internet, allowing participants around the world to collaborate.

Scientists have developed a brain implant that noticeably boosted memory in its first serious test run, perhaps offering a promising new strategy to treat dementia, traumatic brain injuries and other conditions that damage memory.

The device works like a pacemaker, sending electrical pulses to aid the brain when it is struggling to store new information, but remaining quiet when it senses that the brain is functioning well.

In the test, reported Tuesday in the journal Nature Communications,the device improved word recall by 15 percent — roughly the amount that Alzheimer’s disease steals over two and half years.

The implant is still experimental; the researchers are currently in discussions to commercialize the technology. And its broad applicability is unknown, having been tested so far only in people with epilepsy.

Experts cautioned that the potential for misuse of any “memory booster” is enormous — A.D.H.D. drugs are widely used as study aids. They also said that a 15 percent improvement is fairly modest.

Still, the research marks the arrival of new kind of device: an autonomous aid that enhances normal, but less than optimal, cognitive function.

Doctors have used similar implants for years to block abnormal bursts of activity in the brain, most commonly in people with Parkinson’s disease and epilepsy.

“The exciting thing about this is that, if it can be replicated and extended, then we can use the same method to figure out what features of brain activity predict good performance,” said Bradley Voytek, an assistant professor of cognitive and data science at the University of California, San Diego.

The implant is based on years of work decoding brain signals, supported recently by more than $70 million from the Department of Defense to develop treatments for traumatic brain injury, the signature wound of the Iraq and Afghanistan wars.

The research team, led by scientists at the University of Pennsylvania and Thomas Jefferson University, last year reported that timed electrical pulses from implanted electrodes could reliably aid recall.

“It’s one thing to go back through your data, and find that the stimulation works. It’s another to have the program run on its own and watch it work in real time,” said Michael Kahana, a professor of psychology at the University of Pennsylvania and the senior author of the new study.

“Now that the technology is out of the box, all sorts of neuro-modulation algorithms could be used in this way,” he added.

Dr. Edward Chang, a professor of neurosurgery at the University of California, San Francisco, said, “Very similar approaches might be relevant for other applications, such as treating symptoms of depression or anxiety,” though the targets in the brain would be different.

The research team tested the memory aid in 25 people with epilepsy who were being evaluated for an operation.

The evaluation is a kind of fishing expedition, in which doctors thread an array of electrodes into the brain and wait for seizures to occur to see whether surgery might prevent them. Many of the electrodes are placed in the brain’s memory areas, and the wait can take weeks in the hospital.

Cognitive scientists use this period, with patients’ consent, to give memory tests and take recordings.

In the study, the research team determined the precise patterns for each person’s high-functioning state, when memory storage worked well in the brain, and low-functioning mode, when it did not.

The scientists then asked the patients to memorize lists of words and later, after a distraction, to recall as many as they could.

Each participant carried out a variety of tests repeatedly, recalling different words during each test. Some lists were memorized with the brain stimulation system turned on; others were done with it turned off, for comparison.

On average, people did about 15 percent better when the implant was switched on.

“I remember doing the tests, and enjoying it,” said David Mabrey, 47, a study participant who owns an insurance agency outside of Philadelphia. “It gave me something to do while lying there.”

“But I could not honestly tell how the stimulation was affecting my memory. You don’t feel anything; you don’t know whether it’s on or off.”

The new technology presents both risks and opportunities. Dr. Kahana said the implants could potentially sharpen memory more dramatically if the approach were refined to support retrieval — digging out the memory — rather than only storage.

Still, as currently devised, the implant requires that multiple electrodes be placed in the brain to determine its high- or low-functioning state (though stimulation is sent to just one location).

This makes it an extremely delicate operation that would likely be reserved only for severe cases of impairment — and certainly not for students cramming for tests, Dr. Voytek said.