IEEE Spectrum June, 2014 - 34

by using electricity to alter the activity
of neurons, and they are now putting
that knowledge to use. DBS, one of the
most exciting experimental treatments
for depression, uses an implanted "brain
pacemaker" that sends steady pulses of
electricity to certain brain regions. It's a
technology that was pioneered to stop
Parkinson's patients' tremors, but it's now
being explored for a dizzying array of neural and psychiatric disorders, including
depression, obsessive-compulsive disorder, and PTSD. "Right now we're at the
beta testing stage of DBS for psychiatry,"
says Helen Mayberg, a neurology professor at Emory University and an authority
on DBS for depression.
More than 100 000 Parkinson's patients
have had electrodes implanted in the
motor control regions of their brains,
where the stimulator's pulses reduce
the activity of neurons that are misfiring.
But for disorders like depression, both
the target for treatment and the mechanism of action are considerably less clear.
"The limiting factor is actually the neuroscience, not the engineering," Mayberg
says. She used brain imaging studies to
pinpoint a particular region, Brodmann
area 25, as overactive in depressed patients, and she has implanted the DBS device in this region of the brains of about
two dozen patients who haven't responded to a slew of medications and therapies.
These test subjects are desperate, so
overwhelmed by depression that they're
willing to undergo experimental brain
surgery. And the results have been remarkable. While antidepressant medications typically take weeks to kick in,
many patients in the DBS experiments
have reported a shift in mood instantly-
literally the moment that the device is
turned on. One patient reported an immediate sense of social connection; another
expressed a desire to go bowling, a pastime she hadn't enjoyed for years. Most
patients have chosen to keep their DBS
systems activated after the formal experi34

jun 2014

north american

ments ended, and Mayberg says she's seen
ample evidence that their improved lives
can't be chalked up to a placebo effect.
"When my patients' batteries die, they
know it," she says.
Despite the dramatic results in DBS depression treatment, there was a setback
in the field last year when a major clinical

Bespoke
Medicine
While engi-
neering will
play a central
role in 21stcentury medicine,
biological
treatments will
hardly vanish. Those treatments will be
shaped by the coming ubiquity of cheap
genome sequencing, which will enable
a new model of personalized genetic
medicine. The change will start in the
maternity ward, where newborns in their
bassinets will receive full genome scans,
resulting in complete printouts of their
genetic vulnerabilities. Then, as those
babies grow up and proceed through life,
their physicians can design custom-made
health-care regimens to ward off trouble
and can prescribe the medications that
their bodies will respond to best. Today
the cost of a genome scan is nearing
US $1000, and the scans are becoming
common in cancer hospitals. When the
price drops to $100, they'll be common
everywhere. -E.S.

trial was halted. The device manufacturer,
St. Jude Medical, announced that the trial
it had funded failed a "futility analysis,"
but it hasn't explained exactly what went
wrong. Mayberg notes that there are many
variables that can influence the effectiveness of DBS; for example, even if the trial
had targeted the correct region, the timing
of the pulses may have been off. St. Jude
may have rushed ahead too quickly, she

SPectrum.ieee.orG

says, trying to create a commercial product before the basic science of how such
devices work is truly understood.
The good news for all would-be brain
engineers is that massive neuroscience
initiatives have recently been launched in
the United States and Europe. The BRAIN
Initiative, announced by U.S. president
Barack Obama in 2013, will dedicate hundreds of millions of dollars to developing new tools that can better record and
analyze brain activity. In Europe, meanwhile, the Human Brain Project is using
supercomputers to simulate a complete
human brain so as to better understand
how it functions. It's very possible that
in 50 years, DBS and other electrical
techniques will be part of mainstream
psychiatry, Mayberg says. But that will
require scientists to know as much about
the workings of a neuron as engineers do
about the workings of an electrode.

once Physical and emoTional disabilities have been conquered, the intellectual failures associated with aging will
be a natural next target, says Theodore
Berger, a professor of biomedical engineering at the University of Southern
California. In fact, by 2064, going cyborg
may simply be the sensible and economical thing to do. "We're living longer, so
aging problems, and cognitive problems
in particular, are going to be more and
more prevalent," Berger says. "The cost
of a cognitive prosthetic will pale in comparison to taking care of a person with
dementia for 20 years."
It's quite possible that Alzheimer's patients of the future will be equipped with
memory prosthetics derived from the devices being invented in Berger's lab today.
His work began with delicate electrodes
inserted into a rat's hippocampus, the
brain structure responsible for encoding memory. Berger first deciphered the
relationship between the input signals
from neurons that process a brief learnILLUStratIoN by

Greg Mably

http://SPectrum.ieee.orG

Table of Contents for the Digital Edition of IEEE Spectrum June, 2014