AAAS: Neuroscience advances pose legal conundrums

"I did it—but it's not my
fault." It's one of the more controversial strategies defendants can use: admitting
they committed a serious crime but arguing that, because of some mitigating factor
such as disease or depression, they should not be held responsible. As new and
improved imaging tools allow for more detailed images of the brain and as our
understanding of behavior and personality becomes more sophisticated,
neuroscientists are increasingly having to come to terms with how their
findings and expertise are being used—or misused—in the courtroom.

Experts in law, ethics, and brain
science highlighted the complexity of the issue by staging a mock trial
yesterday in San Diego, at the annual meeting of the American Association for
the Advancement of Science. As the two sides argued for and against the
introduction of MRI data in a murder trial, the complexities piled up: how to
reconcile previous case law dealing with neuroscientific evidence, how MRI data
might bias the jury for or against the defendant, whether brain scans
consistently reveal damage or disease, how closely brain scan results reflect
the psychological states of mind relevant in criminal cases, and so forth.

Neuroscience and law have had a rocky
relationship in recent years; in particular, many researchers have said that
functional MRI (fMRI), which looks at patterns of brain activity, has been
used prematurely in courtrooms as a form of lie detection service
. The mock case,
however, revolved around structural MRI, which offers a detailed 3-D image of a
person's brain. Such a scan showed a severe frontal lobe lesion in a fictional
defendant who was tightly linked to a murder by both forensic evidence and
witness testimony.

The scenario played out in two phases.
The judge first heard arguments and testimony over whether the MRI data should be
admitted into evidence; after he ruled in favor, the participants skipped
forward to near the end of the trial, when two expert witness, neuroscientists James Brewer and
Michael Rafii
of the University of California, San Diego, took the stand, respectively, for
the defense and prosecution.

Brewer cited studies that suggest that
frontal lobe damage can lead to poor impulse control, difficulty in formulating
plans, lack of concern for social conventions, and personality changes. His
testimony led the defense attorney, played by Robert Knaier, an associate in
the San Diego office of Latham and Watkins, to argue that the defendant
"could not have formed the requisite intent" to be held responsible
for his crime.

Rafii, on the other hand, pointed out
that the link between brain damage and personality change is extremely
tenuous—some people exhibit similar shifts in behavior without any sign of
brain lesions, and others with much greater levels of damage show no adverse
affects at all.

"Frankly, we have a naked
brain," said prosecuting attorney Hank Greely, a
professor of law at Stanford University, in his closing arguments. "The
law doesn't care about brains. It cares about minds." While brains
generate minds, he added, the relationship is "not simple and
straightforward" and cannot be used in this case to excuse the defendant's

Between the two phases and after the mock-trial, the players broke character to discuss the implications of their arguments and answer questions from the audience. Many of the concerns were similar. Both groups, for instance, worried about whether a series of successful defenses based on neuroscience would erode the concept of personal responsibility and what do about people declared not guilty because of a neurological disorder but who remained a danger to society. But most of the anxiety revolved over whether it was even appropriate to consider using cutting-edge neuroscience in the courtroom. With research findings being revised and refined on the basis of new data and very few solid causal links between features of the brain and any aspect of behavior, many people worried that the law was racing ahead of the science.

If the session's organizers didn't have
answers to those hard questions, and acknowledged that missteps are likely as
judges and scientists grapple with extremely difficult legal and ethical
issues, they did at least suggest that there is still time to change things.
Greely said that, despite its high profile, neuroimaging is still used
relatively rarely in criminal proceedings. In an ongoing survey of all
California criminal cases between July 2006 and July 2010, he has identified
only 40 candidate cases in which a brain image of a defendant was offered as
evidence; when the work is completed, he expects that number to end up
somewhere between 30 and 100, out of tens of thousands of total cases. Rather,
MRI scans of crime victims are used more often, he said, to detail the extent
of their injuries. When it comes to the more controversial fMRI, cases are even
more uncommon. Although employed with some regularity in civil proceedings,
Greely said he knows of only one criminal case in which fMRI was used—an
Illinois case in which a brain scan was unsuccessfully offered up to help
mitigate a capital sentence.

–Aalok Mehta

Magnetic brain scans become more attractive

The first image many of us conjure up when someone mentions
brain scanners—whether for medical diagnosis or basic research—is the sterile
white isolation and intimidating din of a magnetic resonance imaging device.
But for many diseases, the key to better diagnosis may not be looking into
brains, as with MRIs, but looking near

A new study appearing
in the Journal of Neural Engineering suggests
that magnetoencephalography (MEG) can identify the vast majority of people
suffering from post-traumatic stress disorder (PTSD).

In MEG, a helmet surrounding the head measures the tiny magnetic
fields generated by the brain’s electrical activity. This offers distinct
advantages and disadvantages over other scanning methods. For instance, MEG is
noninvasive, unlike positron emission tomography (PET), which requires patients
to ingest a mildly radioactive solution. MEG is also very fast—it works in
about 10 milliseconds—because it measures neural activity directly; MRIs
measure blood flow in the brain instead and take 20 times longer. On the other
hand, readings from MEG offer less spatial resolution than many other scanning
methods and provide less precise information about regions deep inside the

In the new research, Apostolos
, a professor of neuroscience at the University of Minnesota
and a member of the Dana Alliance for
Brain Initiatives
, and his colleagues found that MEG correctly identified at
least 67 of 74 veterans suffering from PTSD, from a group that also included
250 people with no reported neurological or mental health issues. The veterans were
a varied group, with participants both from the current Iraq and Afghanistan
campaigns as well as from World War II and Vietnam.

The researchers also reported that the strength of their
readings corresponded with the severity of symptoms in a PTSD sufferer. In other
words, a MEG test might not just identify who has PTSD but also how damaging
the disorder is and even what treatments might work best.

MEG has shown potential to diagnose other brain symptoms. In
2007, for instance, Georgopoulos and his team reported that MEG could
help detect
multiple sclerosis, Alzheimer’s disease, schizophrenia,
Sjögren’s syndrome, chronic alcoholism and facial pain. And earlier this month,
we reported on a small
study that used MEG to identify children with autism

As we mentioned in that post, small tests such as the PTSD
study aren’t useful in the clinic until they have been confirmed in more
expansive tests with more diverse sets of people. Still, many neurological
disorders, including a large percentage of PTSD cases, are difficult and
time-consuming to diagnose. Objective detection methods such as brain scans could
dramatically shorten that process, as well as reduce uncertainty about the
accuracy of a diagnosis or the severity of a particular case.

For soldiers, who are at high risk for PTSD, this is
crucial; their final diagnosis can drastically alter what jobs they are
expected to do, where they are sent during their next deployment and what kind
of benefits they can receive. In the most extreme cases, a doctor’s finding might
mean the difference between re-entering a dangerous war zone and safely recovering
from trauma on U.S. soil. For those kinds of cases, a fast, efficient way to
assess PTSD can’t come fast enough.

—Aalok Mehta

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