Neuroscientists have
discovered a method for people to overcome fear without the need to face the
fearful impulse that triggers their body’s defense mechanism.
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How to treat fear?
The best and
the most successful treatment for PTSD to date is what is called ‘Exposure
Therapy’, it involves continually recalling fearful memories again and again
until the part of the brain responsible for the recall of the memory associated
with the fearful stimulus is completely inhibited. The problem with this for
this to work people should be willing to get exposed to the fearful stimulus
and go through the excruciating process several times which is very challenging
to begin with.
According to new research done by a group of neuroscientists
in Japan, they discovered a new method to reduce fear without the need for
conscious exposure to the fearful stimulus. This could make the clinical
treatment much more tolerable and reduce the aversion in patients.
What is the new method?
In this new
method, scientists were able to completely reduce the fear response by
dissociating the fearful memories from the stimulus that triggers them by
associating them with more positive memories. This was demonstrated by a novel
way of conditioning and counter-conditioning the brain with feedback.
The experiment
The
scientists invited a group of 24 people of which 17 people were selected to experiment.
The subjects who were selected for the experiment were asked for prior written
consent for the experiment. The experiment was done over a space of 5 days and consisted
of the acquisition and conditioning of fear stimuli during the first day, counter-conditioning of the fearful stimuli carried out over the next
three days, and a testing phase that takes place on the last day.
During the
acquisition, the subjects underwent a retinotopy session to map the exact
location of the primary and secondary visual cortex (V1 and V2). They then
underwent the process of conditioning of the fear stimulus where they ‘acquire’
the fear memories.
For this,
the subjects were shown two images of different colors (red and green) and they
were given mild electrical shocks at the end of each image they were given two
other images (blue and yellow) without electric shocks at random. Electrodes
were placed in the subject's skin to measure their physiological skin
conductance which acts as a good measure of the fear response. By the end of
the session, the subject seems to have heightened skin conductance of
electricity in response to the images of green and red colors. This suggests
that the subjects have acquired a fear of the green and red images. The
subjects also underwent MRI scans to record the neural connections in their
visual cortex in response to the green and red images.
In the next
three days, the subjects were shown images of grey circles, and their brain was
scanned in an MRI. They asked the subjects to somehow increase the size of the
grey circle mentally and they projected the feedback image taken from the MRI
scans back to them. The subject was given money relatively according to the
size of the circle, the bigger the circle more money they got. However, what
the scientists were not telling the subject was that the size of their
resulting size of the grey circle from their MRI scans was directly
proportional to the resemblance in neural connection to the red and green
images taken after the acquisition phase.
This means
that the grey circle is bigger for the subjects who unconsciously think of any
one of the green and red images that trigger their fearful response. As a
result, the subjects who were initially conditioned to fear responses were now
being counter-conditioned to a more positive response of monetary gain.
After three
days the subjects were tested for the changes and the effects of the
experiment. The subjects were given 4 random shocks to check whether the fear
memories could be triggered by a reexposure. Then the subjects were randomly
shown green, red, blue, and green images and their skin conductance and brain
MRI scans were observed closely.
Results
The subjects
seem to have reduced response in their skin conductance in comparison with the observation
after the acquisition phase. They also have reduced activity in their amygdala
a part of the brain responsible for fear response as seen from the brain scans
in comparison to that taken soon after the acquisition phase.
There was
increased activity of the striatum especially the caudate which is a part of
basal ganglia which may hint at its involvement in the underlying mechanism
that is still unknown. There was also a stark disconnect between the activity
of the visual cortex with a region in the cerebrum called ventromedial
prefrontal cortex*(VMPFC). This is in contrast with the standard exposure
therapy where the VMPFC seems to have an extensive mediating role in inhibiting
the amygdala.
The MRI
scans taken during the testing phase similar brain patterns in visual areas in
response to all colors as those taken after the acquisition phase this means
that the results were not merely due to a change in visual perception as there
is no change in visual perception in the two scans.
Conclusion
There is
still more research that needs to be done on the underlying mechanism of fear
reduction in this method but the results show that the method is very efficient
in reducing fear with the need for any need to be exposed to the fearful
stimulus. In conclusion, fear can be completely cured without the need for
people to face it. Hence this is an attractive option for treating various fear-related
disorders such as PTSD.