Babies and Hate
Olfactory-amygdala-insula interaction, attitudes on abortion, and the impact of political disposition on the human life-cycle
by Charles Brack
"Come on granny, there's a fetus on the way, quit wasting social security, and get in that box": conservatism and the acceleration of the human life cycle
Why do the liberals, presumably under the influence of their more empathetic right hemispheres, and sometimes willing to risk their lives protecting species as genetically distant as trees, tend to support abortion rights? Why doesn't the fetus attain a higher status in their hierarchy of life?
And can somebody explain the religious conservatives? Why does the fetus reach such an exalted status in their hierarchy of life? To them, the fetus is king, and few (if any) living entities take precedence. When did the fetus become lord and master of the universe?
The newborn and the adult seem to generate different empathetic responses in humans, with the newborn eliciting more empathy and a much higher investment in altruism. But the fetus? Is the same empathetic responsiveness for newborns operative for fetuses too? Or are the neural mechanisms that regulate empathy towards fetuses, newborns, children, adults, and the elderly, all slightly different?
We think so, but before we get into the theory of age-dependent human empathy, let's take a stroll down the evolutionary trail of politics, religion, and reproduction.
The reproductive dichotomy theory of conservatism and liberalism
As we have previously noted, most political and religious attitudes can be traced directly to Darwinian reproductive strategy. Attitudes about abortion, gay marriage, the environment, taxation, race, women's rights, gun control, etc., are all enmeshed with reproduction to some degree.
A recent newcomer to this list of political-religious-Darwinian reproductive strategies is birth control. Birth control? What year is this? While this issue might seem silly to the liberals, there is no better evidence for a reproductive dichotomy theory of conservatism and liberalism than birth control.
There are no greater practitioners of Darwinism than the religious conservatives. Religious conservatism is about elevated reproduction. While religious conservatives can vary substantially in their religious beliefs and practices, one thing remains constant: higher rates of reproduction. As a result, they induce constant genetic drive into the population gene pool, and their political-religious beliefs support this fundamentally Darwinian behavior.
As such, conservatives do several interesting things to their social groups: increase the rate of marriage and marital longevity; reduce average group age (via a higher percentage of children); focus group altruism towards the youngest population segments and away from the oldest; reduce average age of conception in females; consume more energy; and, organize and focus their prosocial behavior in smaller groups (e.g., church groups).
Anti-abortion attitudes are central to the reproductive imperative of religious conservatism, but their elevated value of the fetus might be neurologically connected to a number of other seemingly unrelated beliefs, such as enhanced fear of outgroups and aversion to gay marriage. Let's take a brief look at the sparse, but interesting research pertaining to the neurological correlates of abortion attitudes.
Neurological evidence pertaining to attitudes on abortion
Some of the earliest evidence about how the brain constructs attitudes on abortion comes from a split brain patient named "LB" (Schiffer, 1998). Schiffer's paper, Different Psychological Status in the Two Hemispheres of Two Split-Brain Patients, is an ambiguous and incomplete account on the left and right brain's attitudes towards abortion and religion, among other attributes. Unfortunately, the presentation of the data for the two patients under study requires several inferences to be made.
One of the patients in the study, AA, was asked questions about abortion and God. Unfortunately, Schiffer never specifically reports the results for AA, while indicating a high degree of matching (74%) between the responses of each hemisphere, although the authors make a casual comment that the right hemisphere in both patients "appeared to hold both religious and moral opinions".
Further complicating the results, the authors make no comment on the religious and abortion attitudes of the left hemisphere, and we can only speculate about what it was thinking. Since AA had several issues that made testing more difficult and less revealing, such as a less developed language capability in his right hemisphere, patient LB was a much better subject.
Schiffer indicates that LB's right brain "did not believe in God or in Christ, but did believe moderately in the soul and quite-a-bit in abortion and justice." Again, Schiffer never indicates the opinions of the left hemisphere, and we can only speculate that given the way Schiffer reports on the right brain, LB's left brain did believe in God and had a less favorable opinion of abortion.
Although Schiffer's paper is unusually ambiguous, it does implicate a spiritual or agnostic right hemisphere, and one that might be more supportive of abortion.
Besides Schiffer, there seems to be no direct evidence on the neurological correlates of abortion attitudes. While abortion questions are used as markers for conservative or liberal attitudes, as far as we know, there are no current neuroimaging studies that identify specific regions of the brain activated by abortion attitudes.
There is also very little indirect evidence. Stanley et al. (2004), in a study of valence and intensity of attitudes, noted that "some individuals have a rapid and unambiguous response to abortion". This clue is perhaps related to the amygdala's role in the automatic evaluation of socially relevant stimuli (Phelps, 2008). However, amygdalar activation in abortion attitudes has yet to be established.
Given the almost complete lack of neurological evidence regarding abortion attitudes, how can we resolve what is going on in the brain? A few things that might help us are a number of cognitive, olfactory, and demographic correlates of abortion attitudes: religiosity (Marsiglio, 1993); reproductive desire (Miller, 1994); population density (Combs, 1982); sense of smell; and, odor preference for newborns.
Cognitive, olfactory, and demographic correlates of abortion attitudes
The olfactory system connects to many structures associated with political and religious disposition
The fact that abortion attitudes vary with the level of religiosity is consistent with the theory that religiosity tends to be more a product of the left brain, and spirituality (or agnosticism and atheism) a product of the right. This is consistent with the finding of Schiffer about abortion attitudes.
But why would the left brain be more likely to promote anti-abortionistic attitudes than the right? We believe there are several reasons for this, and the first reason traces directly to one of the most well established dichotomies of conservatives and liberals: cognitive ambiguity.
The role of cognitive ambiguity in abortion attitudes
When does life begin? At conception? At birth? When the fetal heart starts beating? Predictably, the liberals maintain a more ambiguous view of the beginning of human life, and are much more likely to say they "do not know".
The cognitively unambiguous religious conservatives are much more likely to believe that life begins at conception. This viewpoint is consistent with the conservative tendency to organize stimuli in binary terms and assign a positive or negative valence to each of those terms: good and evil; freedom and slavery; heaven and hell, etc. The liberals take a less discrete view.
Therefore, the unambiguous cognitive styles of conservatives, which are linked to the general mode of ambiguity reduction in the left hemisphere, is playing a larger role in their social attitudes. At the same time, the secular liberals exhibit more tolerance for ambiguity and a correspondingly ambiguous attitude on the beginning of life. Tolerance for ambiguity is a more of a trait of the right hemisphere, as the right hemisphere does not drive for ambiguity reduction to the same degree as the left (see Visuospatial orientation and religious belief).
The role of age-dependent empathy in abortion attitudes
There is an increasingly popular opinion among religious conservatives that abortion should still be illegal in cases of rape or incest. While this seemingly unempathetic viewpoint towards the mother is partially related to their belief that life begins at conception, we have reason to believe that empathy of the religious conservatives is more age-dependent than secular liberals. That is, relative to liberals, conservatives aren't nearly as fond of adults as they are of babies.
While both liberals and conservatives tend to be less empathetic towards the elderly, the conservative reduction in empathy is relatively greater (perhaps partially explaining the conservative attack on Social Security and Medicare).
Empathy differential: babies versus adults
The above graph depicts the self-reported empathy differential of babies compared to adults. In a Neuropolitics.org survey, 1,703 people were asked to rate their relative empathy for babies versus adults on a scale of -5 to 5 (0 = no difference in empathy between adults and babies). The higher the score, the greater the empathy difference in favor of babies. (Unfortunately, we did not differentiate between adult males and females in this survey, but we suspect females elicit greater empathy from both genders than do males of the same age).
As can be seen above, the conservatives have a much higher value of babies versus adults. While a theory of age-dependent empathy has yet to be elaborated, we suspect that the magnitude of empathy decreases in a fairly linear manner with age. This implies that babies elicit the highest level of empathy, followed by toddlers, young children, and pre-teens. The position of the fetus in this hierarchy seems to vary more across political-religious disposition, with the religious conservatives positioning the fetus closer to babies than liberals.
Further, this implies that the elderly elicit the lowest levels of empathy, which is consistent with the evidence that people tend to be prejudiced against the elderly (Castelli, 2005).
The role of male and female reproductive strategy in abortion attitudes
Variations of empathy levels towards race, gender, religion, and age are all grounded in the same phenomenon: empathy variations towards genetic distance. However, the preference for fetus over mother seems to also have roots in male versus female reproductive strategy.
As a general rule, an average female's genes have a greater chance of making it into the gene pool in the next generation than does an average male's. This is due to greater female reproductive investment and their resulting selectivity in choosing a breeding partner.
The result is not good for males: the percentage of males that reproduce at least one offspring is less than the percentage of females. Female sexual selection is one of the great accelerators of human evolution and might be the single greatest contributor to the rate of evolution of our species.
Controlling female reproductive output and access to abortion neutralizes some of the female advantage in sexual selection, and leads to greater male reproductive success. In general, increasing male dominance increases the rate of reproduction. Variations in male and female attitudes on abortion reflect this fundamental conflict of male and female reproductive strategy.
The influence of olfaction on political-religious attitudes
So far, the evidence points to olfaction as being the most sexually dimorphic of the sensory systems. This is mainly due to the phylogenetically ancient role of chemosensation in managing organism behavior prior to the emergence of the sensory systems of vision and hearing.
Since olfaction is fundamentally a system of chemosensation, that is, the detection of a large class of airborne molecules, it has an enhanced role across many categories of behaviors and emotions that have connections to political behavior: predation and predator avoidance; fear and disgust; mating and maternal bonding; dominance and submission; reward seeking, etc.
Interestingly, the olfactory system has close connections with several key regions of the brain implicated in political-religious disposition, such as the amygdala and the insular, orbitofrontal, temporal, and entorhinal cortices. Further, the olfactory system is of particular political relevance because of its connections with sexually dimorphic structures in the amygdala and hypothalamus, which have both been implicated in hetero and homo sexual orientation.
We have previously made the proposal (2005) that conservatives of both genders were more sexually dimorphic than liberals. This proposal implicated a higher ratio of testosterone to estrogen in the conservative male, and a higher ratio of estrogen to testosterone in the conservative female. The liberal males and females had lower ratios.
The rationale for this proposal was based on several traits associated with conservatives that implicate a greater degree of sexual dimorphism: elevated propensity to be in a heterosexual pair-bond relationship; elevated levels of reproductive output; and, lower age at first pregnancy.
The proposal that conservatives sexually mature more quickly is perhaps warranted on the grounds of the substantial conservative advantage in reproductive output. Given the relationship between sexual dimorphism and the olfactory system, it might also indicate an elevated role of olfaction among the religious conservatives.
Indeed, religious conservatives report greater olfactory sensitivity than liberals. But how is olfaction related to sexual dimorphism and political-religious disposition?
Babies and hate
Two brain structures linked to sexual dimorphism are the medial amygdala and the ventromedial region of the hypothalamus, which not so coincidentally, maintain connections with each other. So far, no study has implicated the hypothalamus in political-religious attitudes. But the amygdala is a different story.
In 2006, Grafman reported that activity in the left amygdala was correlated with the degree of affiliation towards one's political party and valence of one's beliefs, which is indeed an important result, and possibly correlated with olfactory sensitivity. Also in 2006, Westen detected a rapidly habituating activation of the left amygdala when subjects were exposed to "emotionally threatening information" about their preferred candidate.
In 2011, Kanai reported an elevation in gray matter volume of the right amygdala in conservatives. Kanai's neuroanatomical study of gray matter volume also found correlations with: increased anterior cingulate volume in liberalism (laterality not reported); increased left insula volume with conservatism; and, depletion of the right entorhinal cortical volume with conservatism (the entorhinal cortex has close connections to the amygdala).
But the linkage of the amygdala to political behavior comes primarily from neurophysiological studies on racism, which itself is correlated with political disposition. In particular, the amygdala reacts to "outgroup" or opposite race faces, as noted by Hart (2000), Phelps (2000), and Richeson (2003). This reaction was presumed to be associated with threat, and raises the question: how does the amygdala assign a negative or positive value depending on the different variations of skin color and facial structure?
While speculative, the origins of the racial preference in the amygdala just might involve the evolutionarily ancient chemical sensing system of smell. Let's look more closely on the structure of the connectivity between the olfactory system and the amygdala.
Previously, we had proposed a very curious relationship between reproductive output and the sense of threat from others, which is playing a critical role in political-religious disposition. Having babies and an elevated sense of threat are not such strange evolutionary bedfellows, as the survival of young offspring is greatly facilitated by parental vigilance against potential threats.
Conservatives have a greater sense of threat from outgroups, and as would be expected, more children. We do not believe this relationship to be purely coincidental, but rather, results from a common neurological foundation. This common foundation appears to substantially involve connectivity between the olfactory system and the amygdaloid and hypothalamic complexes, along with the insular cortex, particularly on the left side.
Sensory inputs to the major nuclei of the amygdala. The amygdala consists of several major nuclei that integrate sensory information and build survivally relevant memories. The medial region (M) is evolutionary older, sexually dimorphic, and closely connected to sexually dimorphic regions of the hypothalamus and instrumental on the activation of the politically-hot monoamine neurotransmitter systems: dopamine, norepinephrine, and serotonin. The left amygdala has also been implicated in the intensity of political beliefs.
The classification of the "amygdala" in its relationship to other regions of the nervous system is controversial, and indeed, Swansen (1998) has proposed that the amygdala is not an integrated anatomical unit, but rather, consists of extended nuclei that belong to other regions of the brain. This controversy is due to the wide bandwidth of sensory integration that exists in the amygdalar region, which works to link multisensory stimuli (olfactory, auditory, gustatory, somatic, and visual) to build survivally relevant and easily retrievable memories that can trigger simple adaptive behaviors (e.g., Pavlovian conditioning).
While anatomical definitions for the various subregions of the amygdala region are often inconsistent and confusing, variations in the functioning of the diverse nuclei seem to be relevant to political-religious disposition. Of particular interest are the medial amygdala, which is closely connected to the accessory olfactory bulb, and has major projections to the ventromedial (suprachiasmic) hypothalamus (Moreno, 2007); and, the central nucleus, which has been implicated in modulating maternal aggression in rats via oxytocin modulation (Lubin, 2003) and vasopressin modulation (Bosch, 2010).
The medial region is sexually dimorphic, and if stimulated, can induce ovulation, uterine contractions, lactation, and lordosis in female rats (Rajendren, 1993). The female medial amygdala is a principle estrogen uptake site, and adjusts immune system activity during the menstrual cycle. In rats, the medial amygdala appears to participate in the expression of both female and male sexual behaviors, such as mounting and lordosis (Cooke, 2003).
Why has evolution disassociated disgust from fear?
The amygdala maintains close connections with the insular cortex, which like the amygdala, is heterogeneous and involved in multi-sensory integration, emotion, and autonomic regulation, along with being closely connected to the olfactory and gustatory systems.
However, it functions at a higher cognitive level than the amygdala, and more adapted for social behaviors: empathy, social emotions, and social norm violations (Sanfey, 2003). The amygdala is more likely to be activated during the expression of fear, while the insula is more activated during the sensation of disgust (Carr, 2003).
Both fear and disgust induce aversive responses to the associated stimulus, however, the disgust reaction is less costly physiologically. Fear responses induce greater changes in the sympathetic nervous system and the adrenal cortical system, while disgust disproportionately engages the parasympathetic system, which lowers heart rate.
Interestingly, activation of the amygdala and insula seem to be engaging the sympathetic and parasympathetic systems in a complementary manner, with fear and disgust having very different physiological impacts, while both inducing aversive behaviors.
Conservative coordination of political-religious beliefs and the left insula
While the amygdala in the left and right hemispheres seem to behave as more of a functional unit, due to their direct linkage via the anterior commissure, there seems to be a great deal of asymmetry in the functioning of the left and right insulas, with substantial implications for political disposition. The evidence currently points to an elevated influence of the left insula in conservative behavior.
In particular, Chiao et al. (2009) found that social dominance orientation (the preference for social hierarchy over egalitarianism) correlated to activation of the left anterior insula and anterior cingulate cortices. Chiao also noted an inverse relationship between empathetic orientation and preference for social hierarchy. Note that Kanai (2011) found that gray matter volume in the left insula of conservatives was greater than that of liberals.
Further, the insula is associated with "disgust sensitivity", which was noted by Inbar (2009) to be strongest in individuals with a high bias against gay marriage and abortion. This was also noted by Haidt (2007). It appears that the neurology that assigns positive and negative valences to olfactory and gustatory stimuli is also being used for more complex social stimuli, and integrated with activity in the dopamine reward system.
The left insula is also more specialized for the sensation of disgust for visual stimuli (Wicker, 2003), which is interesting, given the greater disgust sensitivity of conservatives, Kanai's anatomical finding of greater gray matter volume in the left insula for conservatives, and Chiao's finding of left insular involvement in social dominance orientation.
This provides a clue to one of the most important aspects of religious conservatism: the stronger desire for coordination of beliefs and behavior. As we have previously reported, religious conservatives are more likely to coordinate the way they think. It can be argued that conservatives generally don't know what to believe about a particular issue until reinforcement from their usual sources of political information. Liberals follow this model to a lesser degree, however, verbal communication is less active in developing and maintaining their particular beliefs.
The elevated disgust sensitivity of conservatives and the left insula's closer connections to the language processing networks in the left hemisphere provides for the communication of disgust and fear via language, which works to facilitates conservative cognitive and behavioral coordination.
Anti-governmental attitudes that are proliferated by conservative talk media may be heavily targeting the insula. Indeed, disgust and fear are consistently evoked by all politically-polarizing talk shows, highlighting the power of the insula and amygdala in our political and religious dispositions. Not so coincidentally, both the amygdala and insula can evoke dramatic physiological change.
The close association of the amygdala, insula, and olfactory system is an evolutionarily ancient and survivally important neural network that modulates physiological states and contributes to both reproductive and social behavior. Further, the insula seems to be integrated into the brain's "salience network", which includes the anterior cingulate cortex, another politically hot region of the brain, and is important to cognitive switching and tending to newer, more relevant environmental information.
This is particularly true of the right insula (Sridharan, 2008), which is instrumental in switching the brain's mode of operation between dorsalateral cortical networks and ventromedial networks. This provides an intriguing connection to the results of the Amodio (2007) experiment, where it was found that conservatives had relatively decreased error-related negativity (ERN), which might be related to their elevated left insular activity and its interference with activation of the right insula.
Life is Evil
As the science
of genetics developed, it became more obvious what was behind the
curtain of the puzzling behaviors of altruism and love. The giants
of population genetics, Fisher, Haldane, and Wright, all dabbled
with this confluence of low genetic distance and altruism, but it
was William Hamilton that formally proposed the theory of kin selection,
highlighted by Hamilton's rule:
C > 0
For there to be an evolutionary value to altruism (as defined by increasing the individual's relative genetic presence in the gene pool in the next generation), the coefficient of relatedness, r, times the benefit B bestowed upon the target of the altruistic act, must be greater than the cost C to the altruist. For example, in performing altruism towards a sibling, (with which 50% of genes are shared and the coefficient of relatedness = 0.5), the benefit of the altruistic act must be more than twice the associated decrease in fitness for the altruist's genes to be increased in the next generation.
However, one of the key factors missing from Hamilton's equation is age and the potential reproductive proficiency of the target of the altruism. This is why parents devote more resources to children that are more attractive and have a greater chance of reproductive success. It is also why children are less likely to donate their organs to their parents compared to their siblings or children.
The addition of age to Hamilton's rule is warranted based on the growing evidence that altruism varies with age, gender, and other contributors to reproductive success.
So the obsessive conservative assault on birth control, abortion, social security, and medicare is not so silly after all. It is the application of expected reproductive capacity to Hamilton's rule. In other words, life is evil.
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Charles Brack, July 2012