S.M. (patient)

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S.M., sometimes referred to as SM-046, is an American woman with a peculiar type of brain damage that physiologically reduces her ability to feel fear. First described by scientists in 1994, [1] she has had exclusive and complete bilateral amygdala destruction since late childhood as a consequence of Urbach–Wiethe disease. Dubbed by the media as the "woman with no fear", [2] S.M. has been studied extensively in scientific research; she has helped researchers elucidate the function of the amygdala. [3]

Contents

Characteristics

An experiment with S.M. revealed no fear in response to exposure and handling of snakes and spiders (including tarantulas), a walk through a haunted attraction (Waverly Hills Sanatorium, specifically), or fear-inducing film clips (e.g., The Blair Witch Project , The Shining , and The Silence of the Lambs ), instead only interest, curiosity, and excitement, though she expressed emotions appropriate to the film content such as happiness and disgust when viewing non-fear-inducing film clips. [3] Research has revealed that S.M. is not immune to all fear, however; along with other patients with bilateral amygdala damage, she was found to experience fear and panic attacks of greater intensity than the neurologically healthy controls in response to simulation of the subjective experience of suffocation via carbon dioxide inhalation, feelings which she and the others described as completely novel to them. [4]

Positive emotions

S.M. is described as very outgoing, extremely friendly, and uninhibited, as well as "somewhat coquettish" (playfully flirtatious) and having an abnormally high desire and tendency to approach others. [5] She is greatly impaired in recognizing negative social cues, such as being incapable of recognizing fear in the facial expressions of other people [1] and having difficulty judging trustworthiness and approachability in the faces of others. [5] [6] These traits are consistent with the fact that she tends to quite indiscriminately approach and engage in physical contact with others. [6] In addition, S.M. appears to experience relatively little negative emotion, [3] whilst simultaneously experiencing a relatively high degree of positive affect, despite great adversity in her life. [5] Accordingly, she tends to be very positive about most people, situations, and issues. [5]

Music

S.M. exhibits impairments in the emotional processing of music; specifically, she shows selectively impaired recognition of sad and scary music. [7]

Danger appraisal

In addition to her lack of fear, S.M. shows a lack of a sense of personal space, and experiences virtually no discomfort standing extremely close to strangers, even nose-to-nose with direct eye contact. She does understand the concept of personal space, however, and acknowledges that other people need more personal space than she does. [8]

S.M. has been the victim of numerous acts of crime and traumatic and life-threatening encounters. She has been held up at both knifepoint and gunpoint, was almost killed in a domestic violence incident, and has received explicit death threats on multiple occasions. Despite the life-threatening nature of many of these situations, S.M. did not exhibit any signs of desperation, urgency, or other behavioral responses that would normally accompany such incidents. The disproportionate number of traumatic events in S.M.'s life has been attributed to a combination of her living in a dangerous area filled with poverty, crime, and to a marked impairment on her part of detecting looming threats in her environment and learning to steer clear of potentially dangerous situations. S.M. herself has never been convicted of a crime. [3] [9]

Memory differences

S.M. shows memory differences. Emotionally arousing stimuli are known to undergo an enhancement of consolidation into long-term declarative memory (see emotion and memory), and this effect appears to be dependent on the amygdala. [10] [11] In accordance, S.M. displays impaired declarative memory facilitation for emotional material, while her memory consolidation for neutral material is normal. [12] [13]

Empathy

S.M. is still capable of being empathic to others despite being less capable of detecting negative emotion from faces; however, her threshold for noticing another person's pain was described as "fairly high". [5]

Personal life

S.M. is white [14] and was born in 1965. [15] She has been married and is a mother of three boys. [3] [16]

S.M. has had a history of adversity in her life, including alienation, hardship, teasing, shunning and abuse from authority figures. [5]

See also

Related Research Articles

<span class="mw-page-title-main">Fear</span> Basic emotion induced by a perceived threat

Fear is an intensely unpleasant emotion in response to perceiving or recognizing a danger or threat. Fear causes physiological changes that may produce behavioral reactions such as mounting an aggressive response or fleeing the threat. Fear in human beings may occur in response to a certain stimulus occurring in the present, or in anticipation or expectation of a future threat perceived as a risk to oneself. The fear response arises from the perception of danger leading to confrontation with or escape from/avoiding the threat, which in extreme cases of fear can be a freeze response.

<span class="mw-page-title-main">Amygdala</span> Each of two small structures deep within the temporal lobe of complex vertebrates

The amygdala is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex vertebrates, including humans. Shown to perform a primary role in the processing of memory, decision making, and emotional responses, the amygdalae are considered part of the limbic system. The term "amygdala" was first introduced by Karl Friedrich Burdach in 1822.

<span class="mw-page-title-main">Limbic system</span> Set of brain structures involved in emotion and motivation

The limbic system, also known as the paleomammalian cortex, is a set of brain structures located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum primarily in the forebrain.

<span class="mw-page-title-main">Fear conditioning</span> Behavioral paradigm in which organisms learn to predict aversive events

Pavlovian fear conditioning is a behavioral paradigm in which organisms learn to predict aversive events. It is a form of learning in which an aversive stimulus is associated with a particular neutral context or neutral stimulus, resulting in the expression of fear responses to the originally neutral stimulus or context. This can be done by pairing the neutral stimulus with an aversive stimulus. Eventually, the neutral stimulus alone can elicit the state of fear. In the vocabulary of classical conditioning, the neutral stimulus or context is the "conditional stimulus" (CS), the aversive stimulus is the "unconditional stimulus" (US), and the fear is the "conditional response" (CR).

<span class="mw-page-title-main">Antonio Damasio</span> Portuguese-American neuroscientist (born 1944)

Antonio Damasio is a Portuguese-American neuroscientist. He is currently the David Dornsife Chair in Neuroscience, as well as Professor of Psychology, Philosophy, and Neurology, at the University of Southern California, and, additionally, an adjunct professor at the Salk Institute. He was previously the chair of neurology at the University of Iowa for 20 years. Damasio heads the Brain and Creativity Institute, and has authored several books: his work, Self Comes to Mind: Constructing the Conscious Brain (2010), explores the relationship between the brain and consciousness. Damasio's research in neuroscience has shown that emotions play a central role in social cognition and decision-making.

<span class="mw-page-title-main">Insular cortex</span> Portion of the mammalian cerebral cortex

The insular cortex is a portion of the cerebral cortex folded deep within the lateral sulcus within each hemisphere of the mammalian brain.

Explicit memory is one of the two main types of long-term human memory, the other of which is implicit memory. Explicit memory is the conscious, intentional recollection of factual information, previous experiences, and concepts. This type of memory is dependent upon three processes: acquisition, consolidation, and retrieval.

<span class="mw-page-title-main">Somatic marker hypothesis</span> Hypothesis that emotional processes guide or bias decision-making

The somatic marker hypothesis, formulated by Antonio Damasio and associated researchers, proposes that emotional processes guide behavior, particularly decision-making.

Reduced affect display, sometimes referred to as emotional blunting or emotional numbing, is a condition of reduced emotional reactivity in an individual. It manifests as a failure to express feelings either verbally or nonverbally, especially when talking about issues that would normally be expected to engage emotions. In this condition, expressive gestures are rare and there is little animation in facial expression or vocal inflection. Additionally, reduced affect can be symptomatic of autism, schizophrenia, depression, post-traumatic stress disorder, depersonalization disorder, schizoid personality disorder or brain damage. It may also be a side effect of certain medications.

<span class="mw-page-title-main">Orbitofrontal cortex</span> Region of the prefrontal cortex of the brain

The orbitofrontal cortex (OFC) is a prefrontal cortex region in the frontal lobes of the brain which is involved in the cognitive process of decision-making. In non-human primates it consists of the association cortex areas Brodmann area 11, 12 and 13; in humans it consists of Brodmann area 10, 11 and 47.

<span class="mw-page-title-main">Ventromedial prefrontal cortex</span> Body part

The ventromedial prefrontal cortex (vmPFC) is a part of the prefrontal cortex in the mammalian brain. The ventral medial prefrontal is located in the frontal lobe at the bottom of the cerebral hemispheres and is implicated in the processing of risk and fear, as it is critical in the regulation of amygdala activity in humans. It also plays a role in the inhibition of emotional responses, and in the process of decision-making and self-control. It is also involved in the cognitive evaluation of morality.

Memory and trauma is the deleterious effects that physical or psychological trauma has on memory.

The Intercalatedcells of the amygdala are GABAergic neurons situated between the basolateral and central nuclei of the amygdala that play a significant role in inhibitory control over the amygdala. They regulate amygdala-dependent emotional processing like fear memory and social behavior. Their function has been best studied with selective ITC ablation which impairs fear extinction, fear generalization, and social behavior. Studies have begun to recognize that ITC clusters may be implicated in reward, addiction, and withdrawal circuits given their heavy expression of dopamine and opioid receptors.

Memory consolidation is a category of processes that stabilize a memory trace after its initial acquisition. A memory trace is a change in the nervous system caused by memorizing something. Consolidation is distinguished into two specific processes. The first, synaptic consolidation, which is thought to correspond to late-phase long-term potentiation, occurs on a small scale in the synaptic connections and neural circuits within the first few hours after learning. The second process is systems consolidation, occurring on a much larger scale in the brain, rendering hippocampus-dependent memories independent of the hippocampus over a period of weeks to years. Recently, a third process has become the focus of research, reconsolidation, in which previously consolidated memories can be made labile again through reactivation of the memory trace.

The management of traumatic memories is important when treating mental health disorders such as post traumatic stress disorder. Traumatic memories can cause life problems even to individuals who do not meet the diagnostic criteria for a mental health disorder. They result from traumatic experiences, including natural disasters such as earthquakes and tsunamis; violent events such as kidnapping, terrorist attacks, war, domestic abuse and rape. Traumatic memories are naturally stressful in nature and emotionally overwhelm people's existing coping mechanisms.

Memory supports and enables social interactions in a variety of ways. In order to engage in successful social interaction, people must be able to remember how they should interact with one another, whom they have interacted with previously, and what occurred during those interactions. There are a lot of brain processes and functions that go into the application and use of memory in social interactions, as well as psychological reasoning for its importance.

Many experiments have been done to find out how the brain interprets stimuli and how animals develop fear responses. The emotion, fear, has been hard-wired into almost every individual, due to its vital role in the survival of the individual. Researchers have found that fear is established unconsciously and that the amygdala is involved with fear conditioning.

Daniel T. Tranel is an American professor of neurology at the University of Iowa. He has been recognized as a fellow of the American Association for the Advancement of Science. While a graduate student at the University of Iowa, he helped establish the Iowa Neurological Patient Registry, which he currently directs. The Iowa Neurological Patient Registry includes cases of unique brain injuries, such as Patient S.M. and Patient E.V.R. Tranel also directs the Interdisciplinary Graduate Program in Neuroscience at the University of Iowa. He serves as editor-in-chief of the Journal of Clinical and Experimental Neuropsychology and is a contributing author to the 5th edition of Neuropsychological Assessment, a classic textbook in neuropsychology used by most neuropsychologists.

Neuromorality is an emerging field of neuroscience that studies the connection between morality and neuronal function. Scientists use fMRI and psychological assessment together to investigate the neural basis of moral cognition and behavior. Evidence shows that the central hub of morality is the prefrontal cortex guiding activity to other nodes of the neuromoral network. A spectrum of functional characteristics within this network to give rise to both altruistic and psychopathological behavior. Evidence from the investigation of neuromorality has applications in both clinical neuropsychiatry and forensic neuropsychiatry.

<span class="mw-page-title-main">Antoine Bechara</span> American neuroscientist

Antoine Bechara is an American neuroscientist, academic and researcher. He is currently a professor of Psychology and Neuroscience at the University of Southern California.

References

  1. 1 2 Adolphs R, Tranel D, Damasio H, Damasio A (1994). "Impaired recognition of emotion in facial expressions following bilateral damage to the human amygdala" (PDF). Nature. 372 (6507): 669–72. Bibcode:1994Natur.372..669A. doi:10.1038/372669a0. PMID   7990957. S2CID   25169376. Archived from the original (PDF) on 2016-03-03.
  2. ↑ Suzzan Babcock (2014-11-25). In Search of Peace: For the Children. Author House. pp. 359–. ISBN   978-1-4969-5336-0.
  3. 1 2 3 4 5 Feinstein, Justin S.; Adolphs, Ralph; Damasio, Antonio; Tranel, Daniel (2011). "The Human Amygdala and the Induction and Experience of Fear". Current Biology. 21 (1): 34–38. doi:10.1016/j.cub.2010.11.042. ISSN   0960-9822. PMC   3030206 . PMID   21167712.
  4. ↑ Feinstein, Justin S; Buzza, Colin; Hurlemann, Rene; Follmer, Robin L; Dahdaleh, Nader S; Coryell, William H; Welsh, Michael J; Tranel, Daniel; Wemmie, John A (2013). "Fear and panic in humans with bilateral amygdala damage". Nature Neuroscience. 16 (3): 270–272. doi:10.1038/nn.3323. ISSN   1097-6256. PMC   3739474 . PMID   23377128.
  5. 1 2 3 4 5 6 Tranel D, Gullickson G, Koch M, Adolphs R (2006). "Altered experience of emotion following bilateral amygdala damage" (PDF). Cogn Neuropsychiatry. 11 (3): 219–32. doi:10.1080/13546800444000281. PMID   17354069. S2CID   40421089. Archived from the original (PDF) on 2015-01-19.
  6. 1 2 Adolphs R, Tranel D, Damasio AR (1998). "The human amygdala in social judgment" (PDF). Nature. 393 (6684): 470–4. Bibcode:1998Natur.393..470A. doi:10.1038/30982. PMID   9624002. S2CID   205000950. Archived from the original (PDF) on 2015-08-13.
  7. ↑ Gosselin, Nathalie; Peretz, Isabelle; Johnsen, Erica; Adolphs, Ralph (2007). "Amygdala damage impairs emotion recognition from music". Neuropsychologia. 45 (2): 236–244. doi:10.1016/j.neuropsychologia.2006.07.012. ISSN   0028-3932. PMID   16970965. S2CID   14537793.
  8. ↑ Kennedy, Daniel P; Gläscher, Jan; Tyszka, J Michael; Adolphs, Ralph (2009). "Personal space regulation by the human amygdala". Nature Neuroscience. 12 (10): 1226–1227. doi:10.1038/nn.2381. ISSN   1097-6256. PMC   2753689 . PMID   19718035.
  9. ↑ Terburg, D; Morgan, B E; Montoya, E R; Hooge, I T; Thornton, H B; Hariri, A R; Panksepp, J; Stein, D J; van Honk, J (2012). "Hypervigilance for fear after basolateral amygdala damage in humans". Translational Psychiatry. 2 (5): e115. doi:10.1038/tp.2012.46. ISSN   2158-3188. PMC   3365265 . PMID   22832959.
  10. ↑ Anderson, Adam K.; Phelps, Elizabeth A. (2001). "Lesions of the human amygdala impair enhanced perception of emotionally salient events". Nature. 411 (6835): 305–309. Bibcode:2001Natur.411..305A. doi:10.1038/35077083. ISSN   0028-0836. PMID   11357132. S2CID   4391340.
  11. ↑ Strange, B. A.; Hurlemann, R.; Dolan, R. J. (2003). "An emotion-induced retrograde amnesia in humans is amygdala- and -adrenergic-dependent". Proceedings of the National Academy of Sciences. 100 (23): 13626–13631. doi: 10.1073/pnas.1635116100 . ISSN   0027-8424. PMC   263864 . PMID   14595032.
  12. ↑ Adolphs, R; Cahill, L; Schul, R; Babinsky, R (1997). "Impaired declarative memory for emotional material following bilateral amygdala damage in humans". Learning & Memory. 4 (3): 291–300. doi: 10.1101/lm.4.3.291 . ISSN   1072-0502. PMID   10456070.
  13. ↑ Adolphs, R. (2000). "Impaired Emotional Declarative Memory Following Unilateral Amygdala Damage". Learning & Memory. 7 (3): 180–186. doi:10.1101/lm.7.3.180. ISSN   1072-0502. PMC   311327 . PMID   10837507.
  14. ↑ Amaral et al. (2016) , p. 17: "For many years, S. M. attended a church where she was the only white person in a crowd of all black people."
  15. ↑ Amaral et al. (2016):
    p. 2: "in 2015 she celebrated her 50th birthday."
    p. 3-4: "On November 7, 1986, Dr. Daniel Tranel met S. M. for the very first time when a neurologist referred her to the Benton Neuropsychology Clinic at the University of Iowa. She was 20 years old [...]"
  16. ↑ Amaral DG, Corbett BA (2003). "The amygdala, autism and anxiety". Autism: Neural Basis and Treatment Possibilities. Novartis Found Symp. Vol. 251. pp. 177–87, discussion 187–97, 281–97. doi:10.1002/0470869380.ch11. ISBN   9780470850992. PMID   14521193.

Bibliography

David G. Amaral; Ralph Adolphs, eds. (2016). Living without an Amygdala. Guilford Publications. ISBN   9781462525959.

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