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Fear

The definition of fear is as follows: "an unpleasant emotion caused by the belief that someone or something is dangerous, likely to cause pain, or a threat."

It's definitely a strange feeling to know that something doesn't exist yet your FEAR takes over. I'm here to break it down into chemical terms on what exactly occurs when you watch that scary movie and are afraid to take a shower afterwards. I'll also explain the different types of fear.

"In humans and animals, fear is modulated by the process of cognition and learning. Thus fear is judged as rational or appropriate and irrational or inappropriate. An irrational fear is called a phobia.

Fear is closely related to, but should be distinguished from, the emotion "anxiety", which occurs as the result of threats that are perceived to be uncontrollable or unavoidable. The fear response serves survival by generating appropriate behavioral responses, so it has been preserved throughout evolution.

According to surveys, some of the most common fears are of demons and ghosts, the existence of evil powers, cockroaches, spiders, snakes, heights, water, enclosed spaces, tunnels, bridges, needles, social rejection, failure, examinations and public speaking.

People develop specific fears as a result of learning. This has been studied in psychology as fear conditioning, beginning with John B. Watson's Little Albert experiment in 1920, which was inspired after observing a child with an irrational fear of dogs. In this study, an 11-month-old boy was conditioned to fear a white rat in the laboratory. The fear became generalized to include other white, furry objects, such as a rabbit, dog, and even a ball of cotton.

Fear can be learned by experiencing or watching a frightening traumatic accident. For example, if a child falls into a well and struggles to get out, he or she may develop a fear of wells, heights (acrophobia), enclosed spaces (claustrophobia), or water (aquaphobia). There are studies looking at areas of the brain that are affected in relation to fear. When looking at these areas (such as the amygdala), it was proposed that a person learns to fear regardless of whether they themselves have experienced trauma, or if they have observed the fear in others. In a study completed by Andreas Olsson, Katherine I. Nearing and Elizabeth A. Phelps the amygdala were affected both when subjects observed someone else being submitted to an aversive event, knowing that the same treatment awaited themselves, and when subjects were subsequently placed in a fear-provoking situation. This suggests that fear can develop in both conditions, not just simply from personal history.

Although many fears are learned, the capacity to fear is part of human nature. Many studies have found that certain fears (e.g. animals, heights) are much more common than others (e.g. flowers, clouds). These fears are also easier to induce in the laboratory. This phenomenon is known as preparedness. Because early humans that were quick to fear dangerous situations were more likely to survive and reproduce, preparedness is theorized to be a genetic effect that is the result of natural selection.

From an evolutionary psychology perspective, different fears may be different adaptations that have been useful in our evolutionary past. They may have developed during different time periods. Some fears, such as fear of heights, may be common to all mammals and developed during the mesozoic period. Other fears, such as fear of snakes, may be common to all simians and developed during the cenozoic time period. Still others, such as fear of mice and insects, may be unique to humans and developed during the paleolithic and neolithic time periods (when mice and insects become important carriers of infectious diseases and harmful for crops and stored foods).

Fear is high only if the observed risk and seriousness both are high, and is low, if risk or seriousness is low.

Process of fear:

  • The thalamus collects sensory data from the senses
  • Sensory cortex receives data from thalamus and interprets it
  • Sensory cortex organizes information for dissemination to hypothalamus (fight or flight), amygdala (fear), hippocampus (memory)

The brain structure that is the center of most neurobiological events associated with fear is the amygdala, located behind the pituitary gland. The amygdala is part of a circuitry of fear learning. It is essential for proper adaptation to stress and specific modulation of emotional learning memory. In the presence of a threatening stimulus, the amygdala generates the secretion of hormones that influence fear and aggression. Once response to the stimulus in the form of fear or aggression commences, the amygdala may elicit the release of hormones into the body to put the person into a state of alertness, in which they are ready to move, run, fight, etc. This defensive response is generally referred to in physiology as the fight-or-flight response regulated by the hypothalamus, part of the limbic system. Once the person is in safe mode, meaning that there are no longer any potential threats surrounding them, the amygdala will send this information to the medial prefrontal cortex (mPFC) where it is stored for similar future situations, which is known as memory consolidation.

Some of the hormones involved during the state of fight-or-flight include epinephrine, norepinephrine and cortisol. Epinephrine regulates heart rate and metabolism as well as dilating blood vessels and air passages. Norepinephrine increases heart rate, blood flow to skeletal muscles and the release of glucose from energy stores. Cortisol increases blood sugar, demarginalizes neutrophilic leukocytes, increases calcium and much more.

After a situation which incites fear occurs, the amygdala and hippocampus record the event through synaptic plasticity. The stimulation to the hippocampus will cause the individual to remember many details surrounding the situation. Plasticity and memory formation in the amygdala are generated by activation of the neurons in the region. Experimental data supports the notion that synaptic plasticity of the neurons leading to the lateral amygdala occurs with fear conditioning. In some cases, this forms permanent fear responses such as post-traumatic stress disorder (PTSD) or a phobia. MRI and fMRI scans have shown that the amygdala in individuals diagnosed with such disorders including bipolar or panic disorder is larger and wired for a higher level of fear.

Several brain structures other than the amygdala have also been observed to be activated when individuals are presented with fearful vs. neutral faces, namely the occipitocerebellar regions including the fusiform gyrus and the inferior parietal / superior temporal gyri. Interestingly, fearful eyes, brows and mouth seem to separately reproduce these brain responses. Scientist from Zurich studies show that the hormone oxytocin related to stress and sex reduces activity in your brain fear center."

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