Fear in Humans and Nonhuman Animals
Overview
Fear is a physiological, behavioral, and emotional reaction to stimuli that an animal encounters (Horwitz, 2013). In many species across the animal kingdom, the physiological reaction results in an increase in heart rate, increased respiratory rate (panting), sweating, trembling, pacing, and possibly urination and defecation. Fear is an appropriate response to environments and stimuli that are potentially harmful to the animal, which could utilize a creature’s fight or flight response and preserve its life. In this resource, fear of human and nonhuman animals, along with potential treatments for fear disorders, is explored and reviewed.
Glossary
Glossary
Respiratory rate
Fear
Fear stimulation
Secretion
Hormone
Limbic system
Fear circuits
Keystone area
PTSD
Somatosensory cortices
Cognitive Behavioral Therapy (CBT)
Claustrophobia
anxiety-based illnesses
Pharmacogenetics
Optogenetics
selective serotonin reuptake inhibitors (SSRIs)
Objectives
Objectives
Understand the neurological background of fear among people
Learn about the fear in a hormonal context - how it is stimulated and what is the trigger that cues fear stimulation
Validate if the fear exists among different species out of humans and in what condition their fear stimulates
Introduction
Introduction
Skyler Martinez
Lehigh University
Fear is a physiological, behavioral, and emotional reaction to stimuli that an animal encounters (Horwitz, 2013). In many species across the animal kingdom, the physiological reaction results in an increase in heart rate, increased respiratory rate (panting), sweating, trembling, pacing, and possibly urination and defecation. Fear is an appropriate response to environments and stimuli that are potentially harmful to the animal, which could utilize a creature’s fight or flight response and preserve its life.
Stimuli and Perception (+Hormones)
Stimuli and Perception (+Hormones)
Jay Kang
Lehigh University
It is well known that hormone secretion is not directly related to fear, fear stimulates the secretion of stress hormones such as epinephrine and cortisol, and they help the body to deal with whatever was causing the fear. In fact, the research by Stark has found that even among humans, the release of cortisol differs among males and females. The experiment was held with males in a two-group, receiving 30mg of cortisol or placebo, to experience fear stimulating paradigm. The result has shown that cortisol has restricted the learning process in males. However, the opposite result has been shown among the females. (Stark, 2006). This research indicates that even among the hormones that are responsible to fear stimulation, we have to acknowledge that these
Furthermore, recent research has shown a new view among the studies. Research by Maldonado suggested that hormones such as corticotropin-releasing hormone, adrenocorticotropic hormone, and glucocorticoids play roles in fear and anxiety roles. Furthermore, the limbic system stimulates fear circuits, functioning as a keystone area of the brain for fear circuits. (Maldonado, 2022) More specifically among PTSD patients a mental disorder which is specifically related to the fear of learning through exceptionally stressful conditions. In fact, the endocannabinoid system plays a key role in fear-related brain circuits by modulating these memories (Maldonado, 2022).
Fear-related signals and responses
Fear-related signals and responses
Skyler Martinez
Lehigh University
An interesting discovery related to complex fear systems can be found in the visual recognition of fearful stimuli. In a study that examined fearful faces as salient stimuli, indicating the presence of threat in the surrounding, there was evidence that fearful faces are preferentially processed in the fear system and connected sensory cortices. This is so even when they are presented outside of the participant's awareness or are irrelevant to the task being performed. Considering this, evidence was collected that showed the somatosensory cortices prioritize fear-related stimuli, primarily to the extent that tactile processing is enhanced in the presence of fearful faces (stimuli) (Bertini et. al, 2021).
Fear-based treatments (learning/unlearning)
Fear-based treatments (learning/unlearning)
Skyler Martinez
Lehigh University
Cognitive behavioral therapy (CBT) is a form of psychological treatment that has been demonstrated to be effective for a range of problems including depression, anxiety disorders, alcohol and drug use problems, marital problems, eating disorders, and severe mental illness (APA, 2017). Exposure therapy, one of many treatments under the CBT umbrella, is the most well-known medium of treatment for phobias and irrational fears. A proper example of cognitive behavioral therapy (CBT) and exposure therapy can be seen in the video below, with Dr. Reid Wilson treating a female patient suffering from claustrophobia. Conducting two notable sessions with the patient, the video shows how exposure therapy is easily considered one of the most effective ways to get long-lasting results in the treatment of specific phobias.
Exposure Therapy for Phobias Video with Reid Wilson
Illustration and schematic of key brain regions involved in fear and extinction learning (Milton et. al, 2019)
Striving for advancements in treatment for fear-related disorders, such as trauma and anxiety-based illnesses, pharmacogenetics, and optogenetics have allowed greater resolution in understanding the neural circuits that underlie fear (see image above). Implications for improving treatment have been made by researchers based on an expanded understanding of these fear circuits. Chronic pharmacological therapy, such as the utilzation of selective serotonin reuptake inhibitors (SSRIs), continues to be implied as an effective approach with observations showing enhanced acquisition of fear learning and delayed extinction learning in rats (Milton, 2019).
Regarding new approaches, there is great interest expressed in directly targeting maladaptive fear memories that contribute to disorders such as post-traumatic stress disorder PTSD. This would allow the treatment of PTSD in patients with remote trauma memories and would avoid ethical issues such as obtaining informed consent in acutely traumatized patients (Milton, 2019). Additionally, the use of behavioral interference techniques rather than a pharmacological amnestic agent had also been introduced by the research team. Their final suggestion to investigate would be proposing treatments that interfere with the reconsolidation of the cue representation that triggers intrusive thoughts and involuntary flashbacks in PTSD (Milton, 2019). Looking to the future, further investigation and experimentation in these approaches may yield promising results for the betterment and treatment of fear-disorder patients, notably those suffering from PTSD and related illnesses.
Animal’s Fear of Humans
Fear observed and expressed in nonhuman animals
Animal’s Fear of Humans
Karla Deleon
Lehigh University
In non-human animals, fear is defined as a psychological, behavioral, and emotional reaction to stimuli that an animal encounters. Stimuli that can cause an animal to express the emotion of fear can be from other animals, humans, noises, etc. When presented with a stimulus, the animal’s parasympathetic system kicks in and can cause autonomic changes such as an increase in heart rate and respiratory rates. Other signs of fear include sweating, trembling, pacing, and changes in the body’s posture (lowering of the body or fleeing/hiding).
As mentioned, animals can be fearful of humans. In a study done on domestic animals, their fear of humans can develop stress for the animals, which can then cause lost production. Much of this can be due to the fact of how the animal is handled by a person; if it is in a manner that seems unpleasant, it can lead to fear.
Video: Canine body language: fear
Pheromonal fear of animals
Pheromonal fear of animals
Jay Kang
Lehigh University
If you have seen National Geographics, you would have witnessed some examples that certain animals recognizing their predator without visually seeing them. This gives a range of thought if there are other communication tools within animals that may shape fear action. Then, the research by Bredy has suggested that pheromone communication may carve a social modulation of associative fear learning among animals. Through the experiment using rodent species, they found that fear of learning or extinction on subsequent extinction learning under the same species supports the effect of associative learning while it was not easily explained by changes in coping strategy (Bredy, 2008). This suggested that animals communicate information transferred through olfactory or pheromone cues (Bredy, 2008).
References and Works Cited
References and Works Cited
Bertini, C., & Ladavas, E. (n.d.). Fear-related signals are prioritised in visual, somatosensory and spatial systems. Neuropsychologia. Retrieved May 4, 2023, from https://pubmed.ncbi.nlm.nih.gov/33253690/
Society of Clinical Psychology . (n.d.). What is cognitive behavioral therapy? American Psychological Association. Retrieved May 4, 2023, from https://www.apa.org/ptsd-guideline/patients-and-families/cognitive-behavioral#:~:text=Cognitive%20behavioral%20therapy%20(CBT)%20is,disorders%2C%20and%20severe%20mental%20illness.
Wilson, R. (2012, November 13). Exposure therapy for phobias video with Reid Wilson. PsychotherapyNet. Retrieved May 4, 2023, from https://www.youtube.com/watch?v=0jZdzjAif60&ab_channel=PsychotherapyNet
Alexandra Kredlow, M., Fenster, R. J., Laurent, E. S., Ressler, K. J., & Phelps, E. A. (2021). Prefrontal cortex, amygdala, and threat processing: Implications for PTSD. Neuropsychopharmacology, 47(1), 247–259. https://doi.org/10.1038/s41386-021-01155-7
Stark, R., Wolf, O. T., Tabbert, K., Kagerer, S., Zimmermann, M., Kirsch, P., Schienle, A., & Vaitl, D. (2006). Influence of the stress hormone cortisol on fear conditioning in humans: Evidence for sex differences in the response of the prefrontal cortex. NeuroImage, 32(3), 1290–1298. https://doi.org/10.1016/j.neuroimage.2006.05.046
AL;, M. (n.d.). Fear not: Recent advances in understanding the neural basis of fear memories and implications for treatment development. F1000Research. Retrieved May 4, 2023, from https://pubmed.ncbi.nlm.nih.gov/31824654/
Bredy, T. W., & Barad, M. (2008). Social modulation of associative fear learning by pheromone communication. Learning & Memory, 16(1), 12–18. https://doi.org/10.1101/lm.1226009
Aztec Animal Clinic. (2016, August 3). Fears, Phobias and Anxiety - Aztec Animal Clinic. https://aztecanimalclinic.com/resources/pet-care-library/canine/fears-phobias-anxiety/#:~:text=Fear%20is%20a%20physiological%2C%20behavioral,and%20possibly%20urination%20and%20defecation.
Rushen, J., Taylor, A., & De Passillé, A. (1999). Domestic animals’ fear of humans and its effect on their welfare. Applied Animal Behaviour Science, 65(3), 285–303. https://doi.org/10.1016/s0168-159