In this paper I will be looking at the
behavioural and physiological processes
involved when an individual experiences
‘fear’. I will be examining the conscious and
unconscious processes entailed in experiencing
dangerous situations. I will also consider the
functional value of the autonomic and somatic
nervous systems in a given situation, and the
crucial link between the psychological and
biological processes of an individual.
The scenario is as follows:
A person is walking through a forest when he
is suddenly confronted by an angry bear. The
person immediately runs for the nearest tree
and climbs it. Half an hour later the forest
rangers arrive to rescue him.
When an individual is confronted with apparent
danger, one of the first reactions is the
‘fight or flight’ response. In other words,
whether the individual stays to confront the
perceived threat, or runs away to avoid it.
This is often considered to be a conscious
decision, based on the individuals knowledge
of particular situations or dangers, it is
also assumed to be evolutionary, from a period
when man encountered physical harm from other
animals on a daily basis.
However, it is now thought that, before a
situation is carefully evaluated via the
conscious mind, a split-second decision is
made unconsciously. Information about a
dangerous situation reaches the ‘amygdala’
(part of the limbic system) which is used in
emotional responses. This information travels
down two different pathways: the ‘direct’
pathway and the ‘indirect’ pathway.
The ‘direct’ pathway is the subcortical
pathway (passing under the cortex) and carries
information unconsciously. The information
travels from the eye to the thalamus and on to
the amygdala. Because this pathway is shorter
it registers any perceived danger more rapidly
and responds far more quickly than the
‘indirect’ pathway. The disadvantage to this
rapid response is that we sometimes react
hastily to a perceived danger which is perhaps
groundless, like jumping at a loud noise.
However, the advantage is that we are capable
of reacting with great speed to avoid
sometimes genuinely dangerous situations.
The ‘indirect’ pathway or cortical pathway
(passing through the cortex) is slower than
the ‘direct’ pathway. Information travels from
the eye to the thalamus through the visual
cortex to the amygdala. This pathway is
thought to be used to assess the situation
after the initial rapid response. It allows us
to consciously consider, for example: how we
should respond or whether or not the danger is
genuine.
Therefore, on witnessing a noisy bear
approaching him our ’subject’ is likely to
react rapidly before he even consciously
registers the existence of the bear. As he
turns to run for the nearest tree, information
via the ‘indirect’ pathway will consciously
begin to register and he will be able to draw
on his knowledge of dangerous situation. He
may know that bears do not climb trees and his
decision to head for the nearest tree may be
based on this thought process. Alternatively,
he may act purely on his emotional instinct to
distance himself from the bear.
He will now need to conserve energy from
non-essential areas of the body to those which
are required to physically remove him from the
situation such as the brain, the heart and
skeletal muscles. At this stage the
’sympathetic system’ will begin to dominate
the ‘parasympathetic system’ in order to
provide a rapid response. The sympathetic
axons of the ANS (the autonomic nervous
system, which regulates internal organs) will
begin to innervate the adrenal glands, which
will subsequently release hormones into the
blood. Hormones such as adrenalin and
noradrenalin will begin to hasten his heart
beat and so rapidly increase blood flow to the
skeletal muscles. Whilst increasing vital
activities the sympathetic system will start
to close down all non-essential activities.
As sympathetic axons of the ANS react, our
’subject’ may not be consciously aware of all
the changes taking place in his body - though
he may detect an increased heart beat, and the
adrenalin flow which now enables his enhanced
mobility. As he runs towards the tree, he may
start to reflect on his predicament and
perhaps consider the possible outcome of his
situation.
Whilst his mind is continuously focussed on
his dilemma, his somatic nervous system has
already begun the process of innervating his
skeletal muscles. Neurons in his primary motor
cortex (part of his somatic nervous system)
are receiving information from other cortical
areas such as the somatosensory cortex. This
information is then relayed from the neurons
and interneurons of the motor cortex to the
motor neurons via the midbrain, pons and
medulla to the spinal cords.
At the most basic neuronal level, cell bodies
project their axons from the spinal cord (CNS)
to the effector organs in the peripheral
nervous system (PNS). The neurons fire by
sending out electrical pulses along axons and
releasing neurotransmitters at the axon
terminals creating the synapse. This process
activates the skeletal muscle, and our
’subject’ is then able to run, and to climb
the tree, using the related muscles in an
attempt to escape from danger.
Once he is settled in a place of relative
safety the parasympathetic system may then
take over from the sympathetic system and
begin to calm processes in the body. The
parasympathetic system may allow systems to
return to normal levels if our ’subject’
perceives that he is out of danger. However,
if he still feels that he may be in danger,
hormone levels may stay high and he will
remain in a state of extreme anxiety. This
level of anxiety may only be decreased once he
is rescued by the forest rangers and he is
able to re-evaluate his situation.
It seems clear that ‘fear’ is something we
have all experienced and view as a natural
emotional response to danger. However, our
reaction to fear, which to some extent, we
tend to take for granted provokes major
underlying physiological changes. These
changes innervate functions that are sometimes
clearly understood by our conscious mind, such
as ‘movement’ to enable us to run from danger.
But there are many others of which we are not
aware, such as the unconscious processing of
information to enable a rapid response to
perceived danger.
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