Somatic marker hypothesis

Last updated
Somatic markers are probably stored in the ventromedial prefrontal cortex (highlighted). Ventromedial prefrontal cortex.png
Somatic markers are probably stored in the ventromedial prefrontal cortex (highlighted).

The somatic marker hypothesis, formulated by Antonio Damasio and associated researchers, proposes that emotional processes guide (or bias) behavior, particularly decision-making. [1] [2]

Contents

"Somatic markers" are feelings in the body that are associated with emotions, such as the association of rapid heartbeat with anxiety or of nausea with disgust. According to the hypothesis, somatic markers strongly influence subsequent decision-making. Within the brain, somatic markers are thought to be processed in the ventromedial prefrontal cortex (vmPFC) and the amygdala. The hypothesis has been tested in experiments using the Iowa gambling task.

Background

In economic theory, human decision-making is often modeled as being devoid of emotions, involving only logical reasoning based on cost-benefit calculations. [3] In contrast, the somatic marker hypothesis proposes that emotions play a critical role in the ability to make fast, rational decisions in complex and uncertain situations. [1]

Patients with frontal lobe damage, such as Phineas Gage, provided the first evidence that the frontal lobes were associated with decision-making. Frontal lobe damage, particularly to the vmPFC, results in impaired abilities to organize and plan behavior and learn from previous mistakes, without affecting intellect in terms of working memory, attention, and language comprehension and expression. [4] [5]

vmPFC patients also have difficulty expressing and experiencing appropriate emotions. This led Antonio Damasio to hypothesize that decision-making deficits following vmPFC damage result from the inability to use emotions to help guide future behavior based on past experiences. Consequently, vmPFC damage forces those affected to rely on slow and laborious cost-benefit analyses for every given choice situation. [6]

Antonio Damasio

Antonio Damasio Antonio Damasio no Fronteiras do Pensamento Porto Alegre 2013 cropped.png
António Damásio

Antonio Damasio (Portuguese : António Damásio) is a Portuguese-American neuroscientist. He is currently the David Dornsife Professor of Neuroscience, Psychology and Philosophy at the University of Southern California and an adjunct professor at the Salk Institute. [7] Damasio heads the Brain and Creativity Institute, and has authored several books: his most recent work, Feeling and Knowing: Making Minds Conscious (2021), explores the relationship between the brain, feelings and consciousness. [8] Damasio's research in neuroscience has shown that emotions play a central role in social cognition and decision-making. [9]

Hypothesis

When individuals make decisions, they must assess the incentive value of the choices available to them, using cognitive and emotional processes. When the individuals face complex and conflicting choices, they may be unable to decide using only cognitive processes, which may become overloaded. Emotions, consequently, are hypothesized to guide decision-making.

Emotions, as defined by Damasio, are changes in both body and brain states in response to stimuli. [1] Physiological changes (such as muscle tone, heart rate, endocrine activity, posture, facial expression, and so forth) occur in the body and are relayed to the brain where they are transformed into an emotion that tells the individual something about the stimulus that they have encountered. Over time, emotions and their corresponding bodily changes, which are called "somatic markers", become associated with particular situations and their past outcomes.

When making subsequent decisions, these somatic markers and their evoked emotions are consciously or unconsciously associated with their past outcomes, and influence decision-making in favor of some behaviors instead of others. [1] For instance, when a somatic marker associated with a positive outcome is perceived, the person may feel happy and thereby motivated to pursue that behavior. When a somatic marker associated with the negative outcome is perceived, the person may feel sad, which acts as an internal alarm to warn the individual to avoid that course of action. These situation-specific somatic states are based on, and reinforced by, past experiences help to guide behavior in favor of more advantageous choices, and therefore are adaptive.

According to the hypothesis, two distinct pathways reactivate somatic marker responses. In the first pathway, emotion can be evoked by changes in the body that are projected to the brain – called the "body loop". For instance, encountering a feared object like a snake may initiate the fight-or-flight response and cause fear. In the second pathway, cognitive representations of the emotions (imagining an unpleasant situation "as if" you were in that particular situation) can be activated in the brain without being directly elicited by a sensory stimulus – called the "as-if body loop". Thus, the brain can anticipate expected bodily changes, which allows the individual to respond faster to external stimuli without waiting for an event to actually occur. [4] The amygdala and vmPFC (a subsection of the orbital and medial prefrontal cortex or OMPFC) are essential components of this hypothesized mechanism, and therefore damage to either structure will disrupt decision-making. [10]

Experimental evidence

In an effort to produce a simple neuropsychological tool that would assess deficits in emotional processing, decision-making, and social skills of OMPFC-lesioned individuals, Bechara and collaborators created the Iowa gambling task. [2] [11] The task measures a form of emotion-based learning. Studies using the gambling task have found deficits in various neurological (such as amygdala and OMPFC lesions) and psychiatric populations (such as schizophrenia, mania, and drug abusers).

The Iowa gambling task is a computerized test in which participants are presented with four decks of cards from which they repeatedly choose. Each deck contains various amounts of rewards of either $50 or $100, and occasional losses that are greater in the decks with higher rewards. The participants do not know where the penalty cards are located, and are told to pick cards that will maximize their winnings. The most profitable strategy turns out to be to choose cards only from the small reward/small penalty decks, because although the reward is smaller, the penalty is proportionally much smaller than in the high reward/high penalty decks. Over the course of a session, most healthy participants come to adopt the profitable low-penalty deck strategy. Participants with brain damage, however, are unable to determine the better deck to choose from, and continue to choose from the high reward/high penalty decks. [12]

Since the Iowa gambling task measures participants' quickness in "developing anticipatory emotional responses to guide advantageous choices", [13] it is helpful in testing the somatic marker hypothesis. According to the hypothesis, somatic markers give rise to anticipation of the emotional consequences of a decision being made. Consequently, persons who perform well on the task are thought to be aware of the penalty cards and of the negative emotions associated with drawing such cards, and to realize which deck is less likely to yield a penalty. [13]

This experiment has been used to analyze the impairments of people with damage to the vmPFC, which has been known to affect neural signaling of prospective rewards or punishments. Such persons perform less well on the task. [1] Functional magnetic resonance imaging (fMRI) has been used to analyze the brain during the Iowa gambling task. The brain regions that were activated during the Iowa gambling task were also the ones hypothesized to be triggered by somatic markers during decision-making. [14]

Evolutionary significance

Damasio has posited that the ability of humans to perform abstract thinking quickly and efficiently coincides with both the development of the vmPFC and with the use of somatic markers to guide human behavior during evolution. [6] Patients with damage to the vmPFC are more likely to engage in behaviors that negatively impact personal relationships in the distant future, but they never engage in actions that would lead to immediate harm to themselves or others. [1] The evolution of the prefrontal cortex was associated with the ability to represent events that may occur in the future. [6]

Application to risky behavior

The somatic marker hypothesis has been applied to trying to understand risky behaviors, such as risky sexual behavior and drug addiction.

According to the hypothesis, riskier sexual behaviors are more exhilarating and pleasurable, and therefore they are more likely to stimulate repetitive engagement in such behaviors. [15] When this idea was tested in individuals who were infected with HIV and were substance dependent, differences were found between persons who scored well in the Iowa gambling test, and those who scored poorly. The high scorers showed a correlation between the amount of distress they reported having over their HIV status, and their acceptance of risk during sexual behavior – the greater the distress, the greater the risk that these people would take. The low scorers, on the other hand, showed no such correlation. These results were interpreted as indicating that persons with intact decision-making abilities are better able to rely on past emotional experiences when weighing risks, than are persons who are deficient in such abilities, and that acceptance of risk serves to ameliorate emotional distress. [13]

Drug abusers are thought to ignore the negative consequences of addiction while seeking drugs. According to the somatic marker hypothesis, such abusers are impaired in their ability to recall and consider past unpleasant experiences when weighing whether to consider drug seeking behaviors. [16] [17] Researchers analyzed the neuroendocrine responses of substance-dependent individuals and healthy individuals after being shown pleasant or unpleasant images. In response to unpleasant images, drug users showed decreased levels of several neuroendocrine markers, including norepinephrine, cortisol, and adrenocorticotropic hormone. Addicts showed lesser responses to both pleasant and unpleasant images, suggesting that they may have a diminished emotional response. [18] Neuroimaging studies utilizing fMRI indicate that drug-related stimuli have the ability to activate brain regions involved in emotional evaluation and reward processing. When shown a film of people smoking cocaine, cocaine users showed greater activation of the anterior cingulate cortex, the right inferior parietal lobe, and the caudate nucleus than did non-users. Conversely, the cocaine users showed lesser activation when viewing a sex film than did non-users. [19]

Criticism

Some researchers believe that the use of somatic markers (i.e., afferent feedback) would be a very inefficient method of influencing behavior. Damasio's notion of the as-if experience dependent feedback route, [1] [20] whereby bodily responses are re-represented utilizing the somatosensory cortex (postcentral gyrus), also proposes an inefficient method of affecting explicit behavior. [21] Rolls (1999) stated that; "it would be very inefficient and noisy to place in the execution route a peripheral response, and transducers to attempt to measure that peripheral response, itself a notoriously difficult procedure" (p. 73). [21] Reinforcement association located in the orbitofrontal cortex and amygdala, where the incentive value of stimuli is decoded, is sufficient to elicit emotion-based learning and to affect behavior via, for example, the orbitofrontal-striatal pathway. [21] [22] This process can occur via implicit or explicit processes. [21]

The somatic marker hypothesis represents a model of how feedback from the body may contribute to both advantageous and disadvantageous decision-making in situations of complexity and uncertainty. Much of its supporting data comes from data taken from the Iowa gambling task. [23] While the Iowa gambling task has proven to be an ecologically valid measure of decision-making impairment, there exist three assumptions that need to hold true.

First, the claim that it assesses implicit learning as the reward/punishment design is inconsistent with data showing accurate knowledge of the task possibilities [24] and that mechanisms such as working-memory appear to have a strong influence. Second, the claim that this knowledge occurs through preventive marker signals is not supported by competing explanations of the psychophysiology generated profile. [25] Lastly, the claim that the impairment is due to a 'myopia for the future' is undermined by more plausible psychological mechanisms explaining deficits on the tasks such as reversal learning, risk-taking, and working-memory deficits. There may also be more variability in control performance than previously thought, thus complicating the interpretation of the findings.

Furthermore, although the somatic marker hypothesis has accurately identified many of the brain regions involved in decision-making, emotion, and body-state representation, it has failed to clearly demonstrate how these processes interact at a psychological and evolutionary level. There are many experiments that could be implemented to further test the somatic marker hypothesis. One way would be to develop variants of the Iowa gambling task that control some of the methodological issues and interpretation ambiguities generated. It may be a good idea to include removing the reversal learning confound, which would make the task more difficult to consciously comprehend. Additionally, causal tests of the somatic marker hypothesis could be practiced more insistently in a greater range of populations with altered peripheral feedback, like on patients with facial paralysis.

In conclusion, the somatic marker hypothesis needs to be tested in more experiments. Until a wider range of empirical approaches are employed in order to test the somatic marker hypothesis, it appears that the framework is simply an intriguing idea that is in need of some better supporting evidence. Despite these issues, the somatic marker hypothesis and the Iowa gambling task reestablish the notion that emotion has the potential to be a benefit as well as a problem during the decision-making process in humans. [26]

Related Research Articles

<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">Frontal lobe</span> Part of the brain

The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere. It is parted from the parietal lobe by a groove between tissues called the central sulcus and from the temporal lobe by a deeper groove called the lateral sulcus. The most anterior rounded part of the frontal lobe is known as the frontal pole, one of the three poles of the cerebrum.

Neuroeconomics is an interdisciplinary field that seeks to explain human decision-making, the ability to process multiple alternatives and to follow through on a plan of action. It studies how economic behavior can shape our understanding of the brain, and how neuroscientific discoveries can guide models of economics.

<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.

<i>Descartes Error</i> 1994 book by António Damásio

Descartes' Error: Emotion, Reason, and the Human Brain is a 1994 book by neuroscientist António Damásio describing the physiology of rational thought and decision, and how the faculties could have evolved through Darwinian natural selection. Damásio refers to René Descartes' separation of the mind from the body as an error because reasoning requires the guidance of emotions and feelings conveyed from the body. Written for the layperson, Damásio uses the dramatic 1848 railroad accident case of Phineas Gage as a reference for incorporating data from multiple modern clinical cases, enumerating damaging cognitive effects when feelings and reasoning become anatomically decoupled. The book provides an analysis of diverse clinical data contrasting a wide range of emotional changes following frontal lobe damage as well as lower (medulla) and anterior areas of the brain such as the anterior cingulate. Among his experimental evidence and testable hypotheses, Damásio presents the "somatic marker hypothesis", a proposed mechanism by which emotions guide behavior and decision-making, and positing that rationality requires emotional input. He argues that René Descartes' "error" was the dualist separation of mind and body, rationality and emotion.

<span class="mw-page-title-main">Prefrontal cortex</span> Part of the brain responsible for personality, decision-making, and social behavior

In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46, and BA47.

Affective neuroscience is the study of how the brain processes emotions. This field combines neuroscience with the psychological study of personality, emotion, and mood. The basis of emotions and what emotions are remains an issue of debate within the field of affective neuroscience.

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">Executive functions</span> Cognitive processes necessary for control of behavior

In cognitive science and neuropsychology, executive functions are a set of cognitive processes that are necessary for the cognitive control of behavior: selecting and successfully monitoring behaviors that facilitate the attainment of chosen goals. Executive functions include basic cognitive processes such as attentional control, cognitive inhibition, inhibitory control, working memory, and cognitive flexibility. Higher-order executive functions require the simultaneous use of multiple basic executive functions and include planning and fluid intelligence.

<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.

The Iowa gambling task (IGT) is a psychological task thought to simulate real-life decision making. It was introduced by Antoine Bechara, Antonio Damasio, Hanna Damasio and Steven Anderson, then researchers at the University of Iowa. It has been brought to popular attention by Antonio Damasio in his best-selling book Descartes' Error.

Hot cognition is a hypothesis on motivated reasoning in which a person's thinking is influenced by their emotional state. Put simply, hot cognition is cognition coloured by emotion. Hot cognition contrasts with cold cognition, which implies cognitive processing of information that is independent of emotional involvement. Hot cognition is proposed to be associated with cognitive and physiological arousal, in which a person is more responsive to environmental factors. As it is automatic, rapid and led by emotion, hot cognition may consequently cause biased decision making. Hot cognition may arise, with varying degrees of strength, in politics, religion, and other sociopolitical contexts because of moral issues, which are inevitably tied to emotion. Hot cognition was initially proposed in 1963 by Robert P. Abelson. The idea became popular in the 1960s and the 1970s.

<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.

One way of thinking holds that the mental process of decision-making is rational: a formal process based on optimizing utility. Rational thinking and decision-making does not leave much room for emotions. In fact, emotions are often considered irrational occurrences that may distort reasoning.

<span class="mw-page-title-main">Impulsivity</span> Tendency to act on a whim without considering consequences

In psychology, impulsivity is a tendency to act on a whim, displaying behavior characterized by little or no forethought, reflection, or consideration of the consequences. Impulsive actions are typically "poorly conceived, prematurely expressed, unduly risky, or inappropriate to the situation that often result in undesirable consequences," which imperil long-term goals and strategies for success. Impulsivity can be classified as a multifactorial construct. A functional variety of impulsivity has also been suggested, which involves action without much forethought in appropriate situations that can and does result in desirable consequences. "When such actions have positive outcomes, they tend not to be seen as signs of impulsivity, but as indicators of boldness, quickness, spontaneity, courageousness, or unconventionality." Thus, the construct of impulsivity includes at least two independent components: first, acting without an appropriate amount of deliberation, which may or may not be functional; and second, choosing short-term gains over long-term ones.

Risk aversion is a preference for a sure outcome over a gamble with higher or equal expected value. Conversely, rejection of a sure thing in favor of a gamble of lower or equal expected value is known as risk-seeking behavior.

The neurocircuitry that underlies executive function processes and emotional and motivational processes are known to be distinct in the brain. However, there are brain regions that show overlap in function between the two cognitive systems. Brain regions that exist in both systems are interesting mainly for studies on how one system affects the other. Examples of such cross-modal functions are emotional regulation strategies such as emotional suppression and emotional reappraisal, the effect of mood on cognitive tasks, and the effect of emotional stimulation of cognitive tasks.

<span class="mw-page-title-main">Dorsomedial prefrontal cortex</span> Area of some species brains

The dorsomedial prefrontal cortex (dmPFC or DMPFC is a section of the prefrontal cortex in some species' brain anatomy. It includes portions of Brodmann areas BA8, BA9, BA10, BA24 and BA32, although some authors identify it specifically with BA8 and BA9. Some notable sub-components include the dorsal anterior cingulate cortex, the prelimbic cortex, and the infralimbic cortex.

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 3 4 5 6 7 Damasio, Antonio R. (2008) [1994]. Descartes' Error: Emotion, Reason and the Human Brain. Random House. ISBN   978-1-4070-7206-7. Descartes' Error
  2. 1 2 Damasio, A.R.; Tranel, D.; Damasio, H.C. (1991). "Ch. 11: Somatic markers and the guidance of behaviour: theory and preliminary testing". In Levin, Harvey S.; Eisenberg, Howard M.; Benton, Arthur Lester (eds.). Frontal Lobe Function and Dysfunction. Oxford University Press. pp. 217–229. ISBN   978-0-19-506284-7.
  3. Loewenstein, G. F.; Weber, E. U.; Hsee, C. K.; Welch, N. (March 2001). "Risk as feelings". Psychol Bull. 127 (2): 267–86. doi:10.1037/0033-2909.127.2.267. PMID   11316014. S2CID   1049219.
  4. 1 2 Damasio, A. (1991). Somatic Markers and the Guidance of Behavior. New York: Oxford University Press. pp. 217–299.
  5. Tranel, D. (1994). ""Acquired sociopathy": the development of sociopathic behavior following focal brain damage". Prog Exp Pers Psychopathol Res: 285–311. PMID   8044207.
  6. 1 2 3 Bechara, A.; Damasio, A.R. (2005). "The somatic marker hypothesis: A neural theory of economic decision". Games and Economic Behavior. 52 (2): 336–372. CiteSeerX   10.1.1.114.1001 . doi:10.1016/j.geb.2004.06.010.
  7. Faculty Profile
  8. Holt, Jim (2021-11-02). "Is It Possible to Explain How Consciousness Works?". The New York Times. ISSN   0362-4331 . Retrieved 2023-09-11.
  9. "Antonio Damasio | Speaker | TED".
  10. Ongur, D. (2000-03-01). "The Organization of Networks within the Orbital and Medial Prefrontal Cortex of Rats, Monkeys and Humans". Cerebral Cortex. 10 (3): 206–219. doi:10.1093/cercor/10.3.206. ISSN   1460-2199. PMID   10731217.
  11. Bechara, A.; Damasio, A. R.; Damasio, H.; Anderson, S. W. (1994). "Insensitivity to future consequences following damage to human prefrontal cortex". Cognition. 50 (1–3): 7–15. doi:10.1016/0010-0277(94)90018-3. PMID   8039375. S2CID   204981454.
  12. Dezfouli, A. K.; Keramati, M. M.; Ekhtiari, H.; Safaei, H.; Lucas, C. (2008). "Understanding Addictive Behavior on the Iowa gambling task Using Reinforcement Learning Framework" (PDF). Proceedings of the 30th Annual Conference of the Cognitive Science Society. pp. 1094–9.
  13. 1 2 3 Wardle, M. C.; Gonzalez, R.; Bechara, A.; Martin-Thormeyer, E. M. (December 2010). "Iowa gambling task performance and emotional distress interact to predict risky sexual behavior in individuals with dual substance and HIV diagnoses". J Clin Exp Neuropsychol. 32 (10): 1110–21. doi:10.1080/13803391003757833. PMC   3639122 . PMID   20480423.
  14. Li, X.; Lu, Z. L.; D'Argembeau, A.; Ng, M.; Bechara, A. (March 2010). "The Iowa gambling task in fMRI images". Hum Brain Mapp. 31 (3): 410–23. doi:10.1002/hbm.20875. PMC   2826566 . PMID   19777556.
  15. Zuckerman, M.; Kuhlman, D. M. (December 2000). "Personality and risk-taking: common biosocial factors". J Pers. 68 (6): 999–1029. doi:10.1111/1467-6494.00124. PMID   11130742.
  16. Bechara, A. (2003). "Risky business: emotion, decision-making, and addiction". J Gambl Stud. 19 (1): 23–51. doi:10.1023/A:1021223113233. PMID   12635539. S2CID   18775801.
  17. Verdejo-García, A.; Bechara, A.; Recknor, E. C.; Pérez-García, M. (May 2006). "Executive dysfunction in substance dependent individuals during drug use and abstinence: an examination of the behavioral, cognitive and emotional correlates of addiction". J Int Neuropsychol Soc. 12 (3): 405–15. doi:10.1017/S1355617706060486. PMID   16903133. S2CID   15939155.
  18. Gerra, G.; Baldaro, B.; Zaimovic, A. (July 2003). "Neuroendocrine responses to experimentally-induced emotions among abstinent opioid-dependent subjects". Drug Alcohol Depend. 71 (1): 25–35. doi:10.1016/S0376-8716(03)00065-6. PMID   12821203.
  19. Garavan, H.; Pankiewicz, J.; Bloom, A. (November 2000). "Cue-induced cocaine craving: neuroanatomical specificity for drug users and drug stimuli". Am J Psychiatry. 157 (11): 1789–98. doi:10.1176/appi.ajp.157.11.1789. hdl: 2262/30226 . PMID   11058476.
  20. Damasio, Antonio R. (2000). The Feeling of what Happens: Body, Emotion and the Making of Consciousness. Vintage. ISBN   978-0-09-928876-3.
  21. 1 2 3 4 Rolls, E.T. (1999). The brain and emotion. Oxford: Oxford University Press. ISBN   978-0-19-852464-9.
  22. Rolls, E. T. (October 1997). "Consciousness in Neural Networks?". Neural Netw. 10 (7): 1227–40. CiteSeerX   10.1.1.100.8154 . doi:10.1016/S0893-6080(97)00049-X. PMID   12662513.
  23. Bechara, A.; Tranel, D.; Damasio, H.; Damasio, A. R. (1996). "Failure to respond autonomically to anticipated future outcomes following damage to prefrontal cortex". Cereb. Cortex. 6 (2): 215–25. doi: 10.1093/cercor/6.2.215 . PMID   8670652.
  24. Maia, T. V.; McClelland, J. L. (November 2004). "A reexamination of the evidence for the somatic marker hypothesis: what participants really know in the Iowa gambling task". Proc. Natl. Acad. Sci. U.S.A. 101 (45): 16075–80. doi: 10.1073/pnas.0406666101 . PMC   528759 . PMID   15501919.
  25. Tomb, I.; Hauser, M.; Deldin, P.; Caramazza, A. (November 2002). "Do somatic markers mediate decisions on the gambling task?". Nat. Neurosci. 5 (11): 1103–4, author reply 1104. doi:10.1038/nn1102-1103. PMID   12403997. S2CID   38397020.
  26. Dunn, B. D.; Dalgleish, T.; Lawrence, A. D. (2006). "The somatic marker hypothesis: a critical evaluation". Neurosci Biobehav Rev. 30 (2): 239–71. doi:10.1016/j.neubiorev.2005.07.001. PMID   16197997. S2CID   207087890.