Fear may represent the most powerful motivator on the spectrum of emotions experienced by human beings. Instigating everything from escaping bodily harm to sweating profusely before an exam, fear substantially molds our cognition and our behaviors. Further supporting the fundamental nature of fear is its universality; all animals, including primitive insects and worms, have demonstrated fear responses to certain stimuli (“Fear in the Brain”, 2003).
Despite its ubiquity, fear signified an incredibly poorly understood concept until relatively recently. Prior to pioneering advances in neuroscience and psychology, uestions concerning the origin of fear (What causes it and where is it processed? ) and its manifestations (How do momentary instances of extreme fear differ from prolonged periods of fear-like feelings? ) were unanswerable. This research paper will aim to answer those questions among others by synthesizing research relevant to a scientific understanding of fear.
Through analyzing the origins of fear in the brain and evaluating the effects of fear on behavior, this paper will attempt to present a compelling explanation of what constitutes this powerful emotion and provide an overview of its more ignificant effects. Relevant terms must be defined before delving into the brain regions that correspond to fear. Although commonly conflated, fear and anxiety are not interchangeable terms for the purposes of this paper. According to renowned author and distinguished psychologist Dr.
Harriet Lerner, fear is an emotion joined with an “intense physiological reaction” to a frightening stimulus whereas anxiety represents a mostly emotional/psychological response to a greater variety of stimuli with fewer somatic consequences (2009). Fear also tends to occur in response to a clearly observable stimulus. In contrast, nxiety typically stems from an origin that is much vaguer in nature and may exist outside the presence of any sort of direct threat.
The pragmatic distinction between the two is that fear can be measured more easily due to its more pronounced biological outputs (sweating, racing heart, etc,); in fact, much of what is known about anxiety has been extrapolated from research on the fear circuitry in the brain (Williams, 2014). However, it is important to note that fear and anxiety are inextricably linked, and the differences between them are not always clear. For instance, high anxiety levels lead to more ronounced fear responses in children who have undergone fear conditioning ( Jovanovich et al, 2014).
This limitation of discriminability becomes very apparent when discussing the conscious experience of fear. Can fear and anxiety be experienced simultaneously? Are fear and anxiety different constructs altogether or do they fall on the same spectrum? While a detailed analysis of these questions lies outside the scope of this paper, distinguishing anxiety’s readily identifiable characteristics from those of fear is essential; given the intangible nature of emotions, comprehending what does not onstitute fear facilitates an understanding of what does through a simple elimination of possibilities.
Fear and anxiety may share a considerable amount of gray area, experiments and information discussed will treat fear and anxiety as separate entities. As all emotions do, fear originates in the brain. Fear is an almost completely autonomic response; people do not purposely trigger it or are even necessarily cognizant of it until after it has run its course (Layton, 2005). The fear response represents a collaborative effort of many different parts of the brain; contrary to the dominant public erception, there is no single “fear center” (this label is most often ascribed to the amygdala) through which the brain processes this feeling.
According to Dr. LeDoux, the world’s preeminent authority on the neuroscience of fear, the amygdala only assumes a couple (but very important) roles in fear processing (2015). The amygdala primarily functions as a threat but the detector. In case studies done on individuals with a dysfunctional amygdala, such as the famous patient “SM”, the results suggest that the amygdala is vital to recognizing fearful expressions in others (Adolphs and Tranel, 1995). In the case of atient SM, there was a complete inability to experience fear from any sort of external threat, including everything from venomous spiders to set up “haunted” houses.
Case studies and lesioning research on lab animals heavily implied that the amygdala functioned alone as the seat of fear in the brain, but further research has countered this assertion. Patient SM and three other individuals with extensive amygdala damage demonstrated signs of panic after inhaling carbon dioxide, a behavior that causes choking (Feinstein et. al, 2013). Whereas the amygdala might be vital for being afraid of external stimuli, nternal problems may instigate fear regardless. Brain imagery scans also reveal that multiple areas of the brain react to threatening stimuli (“Fear in the Brain”, 2015).
While more research is certainly warranted, these data suggest that fear is an experience that cannot be solely attributed to the amygdala and supports Dr. LeDoux’s hypothesis that the amygdala is a type of alarm system. While the amygdala is responsible for releasing certain chemicals that increase the organism’s alertness in response to the threat, other regions of the brain contribute to the conscious processing of that threat (Panksepp, Fuchs, and lacobucci, 2011). The sensory cortex and thalamus, for instance, process the sensory input that leads to a fear response.
The hippocampus may establish a context through which fear stimuli can be interpreted (e. g. traumatic memories can provoke a fear response even when the individual is in a nonthreatening environment), and the hypothalamus activates the so-called “fight or flight” reaction that is associated with extreme fear. In a sense, these regions can be viewed as sort of cognitive assembly line that, through the sum of its parts, creates the human experience, both conscious and nconscious, of fear (LeDoux, 2015).
While the nuances of a conscious experience of fear elude scientists, much is known about the unconscious process of interpreting fear in the brain. Known as the high and low roads (or the long and short routes respectively), the human brain has two distinct methods of processing fear that take place simultaneously (“How Fear is Processed”, 2014). The low road is the more immediate of the two. For instance, a person who just heard a sudden thud in an otherwise quiet library would initially experience the low road of fear processing.
The thalamus of this person would immediately send the sensory information to the amygdala which in turn alerts the hypothalamus to initiate a “fight or flight” response. This low road can be viewed as a “freak out now, think later” approach; it’s the body’s way of preparing an individual to potentially deal with a dangerous situation. As the short road immediately initiates a flight or fight response, the long road is concerned more with discerning the nature of the threat (Layton, 2005).
Using the same example as before, the thalamus also sends information to the sensory cortex right after the thud occurs. This cortex then forwards the information to the hippocampus that establishes context. Essentially, this is the step that allows the individual in the example to determine that the thud is merely a book instead of something more dangerous. Finally, the hippocampus sends a message to the hypothalamus in order to stop the “fight or flight” response.
Despite serving different and sometimes completely opposite functions, both roads of fear processing ultimately end up in the same place: the hypothalamus. This region of the brain and its critically important role in triggering the “fight or flight” response oint to the evolutionary purpose of fear: maintaining survival (Misslin, 2003). This goal can be achieved in many ways other than the typical methods previously discussed; for instance, humans innately have the ability to anticipate threats that may not actually exist, and the fear response initiated by a readily observable one.
In order to activate these “anticipatory defensive measures” associated imagined threats provoke the same with the fear response, the hypothalamus activates both the sympathetic nervous system and the adrenal-cortical system (Layton, 2005). Both contribute to the release of adrenaline into he bloodstream that initiates upticks in both blood pressure and heart rate. The effects of this adrenaline distribution include tensing of certain muscles and relaxing the smooth muscle to allow for more oxygen to enter the lungs.
While only a few animals have something that resembles the human conscious experience of fear, all animals demonstrate this type of response (“Fear in the Brain”, 2003). In short, contrary to its negative connotation, fear serves a mostly beneficial purpose of keeping the organism alive. As with most concepts in neuroscience, the sheer breadth of the subject matter related to ear cannot be completely captured in five pages, and there is much still so much to learn.
Due to its diversity, the above summary of the processes, anatomy, and purpose of fear may raise more questions than it answers regarding the conscious nature of fear or how animals may differ in experiencing it. However, the holistic nature of the research sampled illustrates the complexity of feeling every person is familiar with, highlighting the fact that a field many consider to be wholly abstract (neuroscience) can begin describing the fundamental emotions of our lives.
