The Neuroscience and Psychology of Fear

Fear, as a phenomenon, is omnipresent. The statement could be easily verified by how common doomsday predictions, fear mongering, and conspiracy theories are. Social events such as Steven Colbert's Rally to Keep Fear Alive are only some of the evidence. Further, many believe that subliminal messages embedded in media somehow influence the human mind. While that seems exaggerated, it is scientifically plausible to show something for such a short time that the brain registers it, but without any conscious awareness of what has been seen. Regardless, such far fetched suggestions are far beyond the topic of the present short essay, the purpose of which is to outline fear conditioning and extinction as documented in the academic literature.

Japan is renown, aside from electronics, anime and other elements, for its shockingly scary movies, a premiere of one of them allegedly being so scary that it had to be banned from show, due to heart attacks at the premiere. Film festivals such as Fantasia center on such thematic motion pictures. Moreover, fear is a strong motivator, and to judge by the horror movie genre and amusement parks popularity, actually a feeling many seek out.

Neuroscientifically, the brain structure mostly associated with the emotion is the amygdala (Wilensky et al., 2006; Pare et al., 2004). Interestingly, anxiety differs from fear in that anxiety is fright of something unconfirmed, whereas fear relates to something certain (i.e. if there is a lion in one's room and one is afraid, then that constitutes fear, but if one thinks there might be a monster under one's bed, then that represents anxiety).

fear

A fearful reaction. CGI (Computer Generated Imagery). Image: Copyright © Univers.GrandQuebec.com

Naturally, fear and anxiety are very important for anxiety disorders and other troubles related to abnormal psychology. Perhaps, the most obvious example of such ailments is GAD (Generalized Anxiety Disorder, characterized by chronic and excessive worry about almost everything).

Further, classical conditioning refers to the technique pioneered by Ivan Pavlov at the beginning of the 20th century. Fear conditioning works in a similar way. A famous story is that of little Albert, who was thus conditioned to fear white fluffy animals. So, fear conditioning works in the same way as classical conditioning. An initially neutral stimulus is repeatedly paired with one that elicits fear, and eventually, the neutral stimulus comes to be experienced as frightening.

dog experiment
 
Classical conditioning - famous Pavlov's dogs experiment explained graphically. CGI (Computer Generated Imagery). US - Unconditioned or Unconditional Stimulus (terms used interchangeably, salivation to food); CS - Condititoned or Conditional Stimulus (sound of a bell, paired repeatedly with food); UR - Unconditioned or Unconditional Response (salivation to food); CR - Conditioned or Conditional Response (salivation to bell sound). Image: Copyright © Univers.grandquebec.com

Widely used in the treatment of phobias (irrational fears, such as acrophobia: fear of heights, arachnophobia: fear of spiders, agoraphobia with or without panic attack: fear of crowded places, claustrophobia: fear of enclosed spaces, and so on). Individuals suffering from these afflictions, often realize that their worries are unsubstantiated, but simply cannot do much about them. Fear extinction takes advantage of the reverse mechanism to treat phobias. For example, in desensitization, a scary stimulus is presented gradually in a safe environment (i.e. supervised by a mental health professional), and in time, the person gets more and more confortable and can potentially get rid of the fear all together.

lion

The lion (pantera leo, feline) has long been considered as symbolizing courage and valor, as evidenced, among other things, by such titles as Richard the Lion Heart. CGI (Computer Generated Imagery). Image: Copyright © Univers.GrandQuebec.com

Finally, Silverstein et al. (2011) explain that fear is processed at different levels in the brain. Thus, there appear to be cortical and subcortical pathways in the brain’s interpretation of aversive stimuli. Using neuroimaging techniques, the authors confirmed the involvement of the amygdala, but also of the thalamus, visual cortex, orbitofrontal cortex (OFC) and prefrontal cortex (PFC).

References:

  • Pare, D., Quirk, G. L. & LeDoux, J. E. (2004). New vistas on amygdala networks in conditioned fear. Journal of Neurophysiology, 92: 117-33.
  • Silverstein, D., Lansner, A., Ingvar, M. & Ohman, A. (2011). A neural model of human fear pathways based on anatomical and neuroimaging data. BMC Neuroscience, 12, P241-2.  From the Twentieth Annual Computational Neuroscience Meeting: Stockholm, Sweden.
  • Wilensky, A. E., Schafe, G. E., Kristensen, M. P. & LeDoux, J. E. (2006). Rethinking the fear circuit: The central nucleus of the amygdala is required for the acquisition, consolidation, and expression of Pavlovian fear conditioning. Journal of Neuroscience, 26: 12387-96.
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