PTSD relates with Fear

Post-traumatic stress disorder (PTSD) is an psychiatric condition that is developed in individual, after experiencing stressful or traumatic life events. According to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5), PTSD is diagnosed based on clusters of symptoms, such as the re-experiencing/having intrusive memories of the trauma, avoidance, negative cognition and mood, and hyperarousal.
a) Intrusive memories-Symptoms of intrusive memories may include:
• Recurrent, unwanted distressing memories of the traumatic event
• Reliving the traumatic event as if it were happening again (flashbacks)
• Upsetting dreams or nightmares about the traumatic event
• Severe emotional distress or physical reactions to something that reminds you of the traumatic event
b) Avoidance-Symptoms of avoidance may include:
• Trying to avoid thinking or talking about the traumatic event, because of fear
• Avoiding places, activities or people that remind you of the traumatic event
c) Negative changes in thinking and mood-Symptoms of negative changes in thinking and mood may include:
• Negative thoughts about yourself, other people or the world
• Hopelessness about the future
• Memory problems, including not remembering important aspects of the traumatic event
• Difficulty maintaining close relationships
• Feeling detached from family and friends
• Lack of interest in activities you once enjoyed
• Difficulty experiencing positive emotions
• Feeling emotionally numb
d) Changes in physical and emotional reactions
Symptoms of changes in physical and emotional reactions (also called arousal symptoms) may include:
• Being easily startled or frightened
• Always being on guard for danger
• Self-destructive behavior, such as drinking too much or driving too fast
• Trouble sleeping
• Trouble concentrating
• Irritability, angry outbursts or aggressive behavior
• Overwhelming guilt or shame
For children 6 years old and younger, signs and symptoms may also include:
• Re-enacting the traumatic event or aspects of the traumatic event through play
• Frightening dreams that may or may not include aspects of the traumatic event

The Behavioral and neurobiological responses to fear is extensively investigated critically by using a paradigm dependent on a Pavlovian learning process called fear conditioning. During this type of learning, a subject is presented with a neutral stimulus (conditioned stimulus), which is typically a light, tone, image, or context. This neutral stimulus is paired with an unconditioned stimulus, which is usually a shock. As the association between the two stimuli is learned, the subject expresses a response that is called the conditioned response. As In humans, a psychophysiological index of fear including measures such as fear potentiation of the acoustic startle reflex, skin conductance response (SCR), or heart rate, as Healthy individuals learn to reduce their fear response to the conditioned stimulus in the absence of a threat. The failure to reduce fear in this way often leads to the development of PTSD . as in one study the part of brain which is respondent to this disorder is amygdala, which is an important region in responding to threat, did not show a bias in activation to any particular face,” . “But there was a definite bias of heightened activity in response to the most frightened expression in brain regions such as the fusiform gyrus, insula, primary visual cortex, locus coeruleus, and thalamus.” the visual cortex was significant because it is not only doing visual processing, but also assessing threats .and the locus coeruleus is responsible for triggering the release of adrenaline during stress or serious threat.
As in the research it is believe these functional brain differences provide a neurobiological model for fear generalization in which PTSD symptoms are triggered by things that merely resemble the source of original trauma.