'Determination' can be induced by electrical brain stimulation
Doctors in the US have induced
feelings of intense determination in
two men by stimulating a part of
their brains with gentle electric
currents.
The men were having a routine
procedure to locate regions in their
brains that caused epileptic seizures
when they felt their heart rates rise, a
sense of foreboding, and an
overwhelming desire to persevere
against a looming hardship.
The remarkable findings could
help researchers develop treatments
for depression and other disorders
where people are debilitated by a lack
of motivation.
One patient said the feeling was
like driving a car into a raging
storm. When his brain was
stimulated, he sensed a shaking in his
chest and a surge in his pulse. In six
trials, he felt the same sensations time
and again.
Comparing the feelings to a
frantic drive towards a storm, the
patient said: "You're only halfway
there and you have no other way to
turn around and go back, you have to
keep going forward."
When asked by doctors to
elaborate on whether the feeling was
good or bad, he said: "It was more of
a positive thing, like push harder,
push harder, push harder to try and
get through this."
A second patient had similar
feelings when his brain was
stimulated in the same region, called
the anterior midcingulate cortex
(aMCC). He felt worried that
something terrible was about to
happen, but knew he had to fight and
not give up, according to a case study
in the journal Neuron .
Both men were having an
exploratory procedure to find the
focal point in their brains that caused
them to suffer epileptic fits. In the
procedure, doctors sink fine
electrodes deep into different parts of
the brain and stimulate them with
tiny electrical currents until the
patient senses the "aura" that
precedes a seizure. Often, seizures
can be treated by removing tissue
from this part of the brain.
"In the very first patient this was
something very unexpected, and we
didn't report it," said Josef Parvizi at
Stanford University in California. But
then I was doing functional mapping
on the second patient and he
suddenly experienced a very similar
thing."
"Its extraordinary that two
individuals with very different past
experiences respond in a similar way
to one or two seconds of very low
intensity electricity delivered to the
same area of their brain. These
patients are normal individuals, they
have their IQ, they have their jobs.
We are not reporting these findings
in sick brains," Parvizi said.
The men were stimulated with
between two and eight milliamps of
electrical current, but in tests the
doctors administered sham
stimulation too. In the sham tests,
they told the patients they were about
to stimulate the brain, but had
switched off the electical supply. In
these cases, the men reported no
changes to their feelings. The
sensation was only induced in a
small area of the brain, and vanished
when doctors implanted electrodes
just five millimetres away.
Parvizi said a crucial follow-up
experiment will be to test whether
stimulation of the brain region really
makes people more determined, or
simply creates the sensation of
perseverance. If future studies
replicate the findings, stimulation of
the brain region – perhaps without
the need for brain-penetrating
electrodes – could be used to help
people with severe depression.
The anterior midcingulate cortex
seems to be important in helping us
select responses and make decisions
in light of the feedback we get. Brent
Vogt, a neurobiologist at Boston
University, said patients with chronic
pain and obsessive-compulsive
disorder have already been treated by
destroying part of the aMCC. "Why
not stimulate it? If this would
enhance relieving depression, for
example, let's go," he said.
