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Course: Wireless Philosophy > Unit 7
Lesson 6: The basis of fearThe basis of fear
In this Wireless Philosophy video, we examine what goes on in our brains when we experience fear. What does it mean when scientists say that the amygdala is “the hub of fear,” and is that accurate? Is there a distinction between the changes our bodies undergo when exposed to threatening stimuli and the processes behind the “phenomenal character” of fear?
View our Neuroscience and Philosophy learning module and other videos in this series here: https://www.wi-phi.com. Created by Gaurav Vazirani.
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Video transcript
In this WiPhi video, we will examine some common
ideas about the neuroscience of fear. Imagine you are in a new city. You’re heading back
to your hotel after dinner. It's dark. It's late. Because there is hardly
anyone around, you're on alert. Suddenly, you hear a
loud noise from behind you, and it feels like your heart
just jumped out of your chest. The hairs at the back of your neck
stand up, your heart is beating fast, your hands have become
clammy, and you are ready to run. You are in a state of fear. This is a common experience. What is the neurobiological
basis for fear? What is going on in our brains
when we have this experience? The prevailing view is that
fear stems from the amygdala, an almond-shaped cluster
of cells in the temporal lobe that detects the emotional
salience of things. A lot of this has to do
with the pioneering work done by the neuroscientist
Joseph LeDoux. In LeDoux’s own words, the amygdala is
the “hub” of fear. But what does it mean to say
that the amygdala is the hub of fear? And is that right? First, when LeDoux says that, he doesn’t mean that fear
stems just from the amygdala. Mental activity, including our emotions,
stem not from specific brain areas, but rather complex
brain systems, comprising many neural circuits, extending
along several regions of the brain. So when LeDoux described the
amygdala as being the hub of fear, what he really meant was that fear
is caused by activity in neural circuits which involve the amygdala. In other words, activity in the amygdala
is a crucial part of the neural activity in the
brain that generates fear. For a long time, this view has gone unchallenged. A quick internet
search for the word ‘fear’ generates countless articles claiming
that fear stems from the amygdala. But this idea has been challenged
by none other than LeDoux himself. According to LeDoux, a lot of his work has
been misunderstood. In fact, he claims that he wasn’t
studying the neural basis for fear at all, but something else, namely the neural underpinnings
of the threat response. What is going on? LeDoux’s original research involved finding
out what happens in the brains of rats when facing threats. He found that their physiological
and behavioral responses when exposed to
threatening stimuli were correlated with activity in
neural circuits involving the amygdala. This was the original basis for saying
that the amygdala is the ‘hub’ of fear. But as LeDoux now acknowledges, to say that the amygdala is responsible for
fear based on this research is misleading. The reason for this
is that the word ‘fear’ in everyday use is different
from that in neuroscience. When neuroscientists
talk about fear, they mean the sorts of
changes our bodies undergo when we are exposed
to threatening stimuli. By contrast, when we
typically talk about fear, we don’t just mean
these sorts of changes. Our common understanding of fear involves
a particular sort of subjective feeling. When we say someone is
experiencing the emotional state of fear, we don’t just mean that
they are disposed to run away. Nor do we just mean that their
body undergoes certain changes, like a racing heart, clammy
hands, sweaty brow, and so on. We also mean
that they feel fearful. There is something
it is like to feel fearful, something that belongs to the subjective
experience of the person experiencing fear. The conscious feeling associated
with the experience of fear is what philosophers call
its ‘phenomenal character’. And the neural circuits responsible
for how our bodies respond to threats might not be the same circuits that
underpin the conscious feeling of fear. In fact, according to some of the latest
neuroscientific work done on emotion, while the amygdala-based
circuitry plays a major role in controlling how our
bodies respond to threat, your brain needs to do a lot more than that
to generate the conscious feeling of fear. More technically, LeDoux thinks that various
kinds of physiological changes your body
undergoes in response to threat involves activity in the evolutionarily
ancient subcortical regions of the brain, which includes your amygdala. But for LeDoux, that’s not enough to generate
the conscious feeling of fear. This feeling arises
from further activity in an evolutionarily
newer part of the brain, namely the neocortex. So is the amygdala
the hub of fear? Not according to LeDoux. For LeDoux, the amygdala is better seen as being
the hub for the brain’s threat circuitry. But the threat response might occur
below the level of conscious awareness. Whatever in the brain
explains our experience of fear must explain why we experience
the conscious feeling of fear. Now think back to when you
felt afraid in that foreign city. It seems like your
brain did two things. It activated the neural circuitry
designed to respond to threats. It’s this circuitry that causes
your heart to beat fast, your palms to get clammy,
and for you to get ready to flee. But in addition, it also activated
neural circuitry that enabled these responses
to be experienced as fear. It is this extra work done
by parts of your brain besides the amygdala that are responsible for
your conscious feeling of fear. So next time someone says the amygdala is
the part of the brain responsible for fear, ask them what they mean. By the word ‘fear’, do they mean the various bodily
changes associated with threat? Or do they mean the
conscious feeling of fear? What we’ve learnt is that the
neural basis for these two things are most likely different. What do you think?