that “the whole thing will cascade in exactly the
direction you want it to,” Widge says.
Shanechi’s group is also trying to learn how
best to stimulate the brain. Using computational
models, she and colleagues recently predicted how
certain kinds of stimulation would change
depression-related brain activity in controlled
ways, keeping the relevant circuit behavior tightly
within a healthy range. Shanechi has been testing
those mathematical predictions, published in the
December Journal of Neural Engineering, in people with implanted electrodes. She is delivering
the sorts of electrical stimulation that her models
pointed to and monitoring the effects.
Clues about how best to stimulate also
emerged from the study in Current Biology,
which described the 44-year-old woman’s calm
mood during stimulation. Single and continuous
electrical stimulation in the orbitofrontal cortex
had different effects in neural tissue both near
and far, the researchers found. This sort of neural tinkering — delivering certain kinds and doses
of electrical current and seeing how the signals
reverberate — is a crucial part of devising closed-loop systems.
The future isn’t now
It may seem unsettling for someone to go about
daily life with a device that dwells in the brain and
has the power to influence emotions. But researchers point out that lots of things change our moods,
such as meditation, exercise and alcohol. Don’t forget the antidepressants, taken by nearly 13 percent
of people over the age of 12 in the United States.
“We think nothing of taking a pill to change our
mood and improve our emotions,” George says.
“I don’t think it’s much different with a device.”
Of course, that device doesn’t exist yet. Scien-
tists still aren’t certain where to stimulate and
how—questions that probably have different
answers for everyone, the data suggest. And even
if the protocols were clear, the hardware that does
the work still isn’t ready. In the recent mood-
altering studies, wires emerging from under
people’s skulls were attached to large external
computers, not ideal for moving around.
To succeed, all of the hardware needs to fit
under the skull, where it would perform lightning-quick assessments and figure out how to tweak
neural behavior when needed. That goal is a long
way off, Widge says. The whole system — including
the electrodes, the processor and the power
source — needs more refinement to be nimble
enough to handle complex algorithms, durable
enough to reside permanently inside a living person and powerful enough to avoid the need for
frequent battery replacements.
Researchers imagine one day using such a
device, and the theories that drive it, for problems other than depression. “If you find it works
for mood, why not use it for other problems,
like addictions?” asks George, who dreams of an
implant that could detect an opioid craving and
instantly counter it.
In fact, some of the brain circuits that Widge,
Dougherty and colleagues are trying to influence
are involved in a person’s predilection to seek
new experiences. And that trait, called novelty-seeking, tracks closely with drug use. The ability
to monitor and control that particular tangle of
brain circuitry could ultimately lead to the device
of George’s dreams.
For now, the possibilities are wide open, experts
say. Chances are good that in the coming years
scientists will gain the ability to tap into the brain
and influence it in precise ways. After all, perhaps
more than any other part of the body, the brain is
designed to continuously transform.
“Evolution spent billions of years giving us a
brain that’s fully capable of changing itself,” Widge
says. The brain can get itself into a depressed
state, but it is also capable of getting itself out of
one. “The machinery is all there,” he says. “We just
need to figure out how to work it.” s
s Vikram R. Rao et al. “Direct electrical
stimulation of lateral orbitofrontal cortex
acutely improves mood in individuals with
symptoms of depression.” Current Biology.
December 17, 2018.
Researchers want to
create a device like this
schematic that can monitor and change neural
activity. Electrode arrays
that sit on the surface of
the brain (white-framed
rectangle) and others
that penetrate deeper
(thin implants shown)
could allow access to
brain regions involved in
mood, addiction or other