The levels of serotonin in the brain influence the ability to compromise political differences?
19 Aug 2022
INTRODUCTION
YuYu’s primary interest is in human biological systems of compromising ideas. This research topic is driven by my curiosity about human social behavior and altruistic motivation to tackle complicated political issues related to it. As far as I know, the only human possesses such a complex social system as politics, and I am determined to deal with issues caused by the tangled social systems using my favorite tool, biology.
In biology, ecology deals with interactions between organisms on a large scale, which includes the understanding of systems that organisms depend on, and it is often about non-human living things. Meanwhile, humans are also organisms depending on biological functions; thus, the study of human interactions and the concurrent systems like politics could also be explained by biology.
As politics can make changes in the form of a society, it is significant that the consequences of political actions determine the general public’s well-being. When the well-being is undermined in a community, there is some bias towards a particular sector, which can prompt conflicts between those with different opinions on the subject. To resolve this issue with the minimum loss of all stakeholders, people need to compromise. However, finding the least compromise for all or meeting as many demands as possible for all requires numerous amounts of time and effort.
All considered, uncovering how humans biologically compromise one another’s ideas potentially gives us new parameters for political measures to cope with conflicting issues. When this research is done, a biological approach can be utilized for decision-making in politics to mitigate conflicts. As for the general public, this study aims to probe political behaviors; hence as mentioned, it is consequently applicable to the well-being of society.
SIGNIFICANCE
Humans’ compromising mechanism in political contexts has yet been understood physiologically. This research, therefore, aims to explain how humans’ physiological mechanisms of compromise work in political contexts.
Political conflicts have been adversities among people all over the world. They are often caused by people who are intolerant of others due to their immutable ideology. There was a study which suggested that human intolerance can be regulated by a neurotransmitter, serotonin (Carhart-Harris & Nutt, 2017). In a study done by Lichters et al. (2016), participants’ serotonin levels in the brain were manipulated before they choose products to purchase. After that the participants were given a compromised choice, however, they tended to be obsessed with their original choice. It indicated that the decrease in the serotonin level led people unlikely to compromise. Meanwhile, in politics, compromising behavior of those who have intolerant political attitudes are said to be relatively low (Arceneaux, 2019). Two studies on human compromising behavior have a similarity: in both cases, people become intolerant of other ideas as their levels of compromise decreased. In spite of that, the effect of serotonin on compromising behavior has yet been studied in political contexts. Thus, my research aims to determine whether the level of serotonin affects human political compromising behavior. Therefore, I hypothesize that “the levels of serotonin in the brain influence the ability to compromise political differences.”
This proposal is of significant biological and social importance as serotonin levels in the brain govern compromising behavior and no study demonstrated that serotonin in the brain affects the ability to compromise political differences. With this project, I will be able to explain physiological mechanisms of political compromising behavior regulated by serotonin. Further, an understanding of this field can be applied to a novel way to mitigate conflicting issues caused by political intolerance.
SPECIFIC AIMS
Human political behavior often causes conflicts among people. One of the causes of the conflicts is failing to settle their differences by mutual concessions, which stems from the intolerance attitudes of people. The physiological mechanism behind human intolerance has been explained by a function of a neurotransmitter, serotonin. Previous study reported that the decrease in the levels of serotonin in the brain leads a person unlikely to take compromising behavior, or in other words, a person becomes intolerant. In political contexts, those who are intolerant of others’ opinions tend to reject them. However, whether the rejection is associated with the compromising ability regulated by serotonin is not clear.
To fill the gap in the knowledge, I will conduct an experiment in which people’s serotonin levels will be manipulated, and their levels of political compromise will be measured. In neuroscience, functions of the brain for a specific behavior are often measured by a functional magnetic resonance imaging (fMRI) which utilizes the blood flow changes in the brain. This method is applicable to visualize the active parts of the brain; however, it fails to distinguish chemical substances causing the activation of the brain, and it cannot examine a number of people at once due to the capacity of each fMRI machine. Thus, my project resolves such limitations by observing the effects of the substance, serotonin, more directly through the results of serotonin-level manipulation and scores from the questionnaire. In attempting to conduct the experiments, I hypothesize that “the levels of serotonin in the brain influence the ability to compromise political differences.”
AIM 1: Evaluate the levels of people’s obsession with their original political stances. I hypothesize that the levels of the obsession increase as serotonin levels decrease. To this end, a questionnaire which measures the levels of people’s obsessions will be given to the participants before and after the treatment. Then, the results will be compared whether there is a significant difference between them.
AIM 2: Evaluate the levels of people’s tolerance towards the different political stances. I hypothesize that the levels of tolerance decrease as serotonin levels decrease. To test this, each participant will be provided with a questionnaire which asks the participant to what degree the opposite-stanced events can be compromised. The same questions will be asked before and after the treatment to compare the results.
IMPACT: When the research is completed, compromising behavior in politics will be explained by a biological aspect. Its application would be of help to evaluate politicians’ physiological conditions, using serotonin levels as an index for inclination of their compromise behavior. Then, the evaluation will be taken into account when offering optimum conditions in which politicians attempt to reach a mutual concession. Therefore, this project becomes a key to mitigate political conflicts by utilizing biological understanding of human compromising behavior.
APPROACH
Preliminary experiment
In order to validate one of the experimental system, the blood testing process of a high performance liquid chromatography (HPLC) with Waters Pico-Tag column (Lee et al., 2011), people who are at their age of 50-59 will be recruited, consisting of 26 females and 26 males. They will be “screened for neurological and psychiatric disorders and given written informed consent before participating in the study. “Exclusion criteria include[s] history of cardiac, hepatic, renal, pulmonary, neurological, psychiatric, or gastrointestinal disorders, medication/drug use, and personal or family history of major depression or bipolar affective disorder (Crockett et al., 2009).”
Next, blood samples of the participants will be collected. A half portion of each blood sample will be examined with the HPLC with Waters Pico-Tag column (Lee et al., 2011) to measure the original concentration of tryptophan and large neutral amino acids (LNAA), and the ratio of tryptophan to other large neutral amino acids (TRP/LNAA ratio) will be calculated. The other half portion of each blood sample will be mixed with tryptophan, then examined in the same way. Then, the difference in the levels of tryptophan between two types of the samples will be calculated, and examined whether the difference is consistent with the amount of tryptophan added to each blood sample. This way, the blood testing process will be validated.
Main experiment
A hypothesis of this research is that “the levels of serotonin in the brain influence the ability to compromise political differences.” To test this hypothesis, I will recruit both female and male participants and women who are at their age of 50-59. I will recruit 26 males and 26 females for one experiment, and conduct the experiment twice. The screening will be done as the preliminary experiment.
To begin with, all participants will take the “obsession test” (Table 1). In the test, participants will be asked to either support or oppose four political statements, choosing how strongly they hold the stance from 5 (Very strong), 4 (Strong), 3 (Moderate), 2 (Not much), or 1 (Do not mind to change).
After the obsession test, “compromise test” (Table 2) will be conducted in which the participants will answer questions asking them to compromise their original stances on a scale of 1 (Absolutely not), 2 (Probably not), 3 (Probably fine) or 4 (Absolutely fine). The scores from both tests will be recorded.
Table. Questions for the obsession test.
| Consider following social affairs, take either support or oppose for each of them and choose to which degree you hold the stance from 5 (Very strong), 4 (Strong), 3 (Moderate), 2 (Not much), or 1 (Do not mind to change). |
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| Q1. Abortion should be legalised in Japan. |
| Q2. The Constitution of Japan should allow Japanese collective self-defense. |
| Q3. The same-sex marrige should be allowed in the Constitution of Japan. |
| Q4. Japan should construct more nuclear power plants. |
Table 2. Questions for the compromise test.
| Consider a person who is against the participant’s stance about each of four affairs in the obsession test, and answer the questions below with provided options: 1 (Absolutely not), 2 (Probably not), 3 (Probably fine) or 4 (Absolutely fine). |
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| Q1. If a person who strongly (Against the participant’s position) wanted to make a speech in your community, should he be allowed to speak or not? |
| Q2. Should a person who (Against the participant’s position) be allowed to teach in a college or university or not? |
| Q3. If some people in your community suggested that a book written by a person who (Against the participant’s position) should be taken out of your public library, would you favor removing this book or not? (Reverse coded) |
| Q4. Should a person who (Against the participant’s position) be able to hold local public office or not? |
Next, the concentration of tryptophan and LNAA will be measured by the validated blood testing process in the preliminary experiment, and the TRP/LNAA ratio will be calculated for all participants.
After that, the participants will be divided into two groups (one group consists of 13 females and 13 males). The first group will be provided with acute tryptophan depletion (ATD) cocktail, which is a mixture of amino acids without tryptophan. The formulation is listed in Table 3 based on Richardet al. (2009). The second group of participants will be treated to a mock cocktail, which is a mixture of amino acids with tryptophan. The participants will take their cocktails orally. Then, the participants rest for 5 hours so that non-tryptophan amino acids outcompete tryptophan from entering into the brain, resulting in a lowered amount of tryptophan in the serotonergic terminals in the brain; hence, lowering the amount of serotonin synthesized in the brain. The process of treating two types of cocktails will be done by the double-blind protocol: neither participants nor providers know who has the mixture with tryptophan or without.
After the rest, blood samples of participants will be collected again to obtain the TRP/LNAA ratio that will be used to calculate the relative change in the levels of serotonin in the brain, comparing the pre and post treatment conditions. Lastly, the participants will take the same obsession and compromise tests that they had before the treatment. The scores will be compared with pretreatment conditions to evaluate the changes in the obsession and compromise levels of the participants.
In analyzing the data, first, the relative change between the original TRP/LNAA ratio and post-treatment TRP/LNAA ratio will be calculated. Then, the distribution of TRP/LNAA ratios of two groups will be tested to see whether the levels of serotonin are significantly different (the significance level is p-value < 0.05 in the two-sample t-test). Second, each group’s result from the obsession test will be organized respectively by calculating a relative change in each participant’s scores of pre and post treatment conditions. Likewise, relative changes of compromise test’s scores will be calculated. Third, the relative changes of the obsession test’s score will be compared between two groups to determine whether there is a significant difference (the significance level is p-value < 0.05 in the two-sample t-test). In the same way, the relative changes of the compromise test’s scores will be calculated to determine a significant difference between two groups.
ANTICIPATED RESULTS
There are four possible outcomes of the experiment: (i) the significant change in serotonin level in the brain influences both levels of obsession and compromise, (ii) the significant change in serotonin level in the brain influences only the obsession level, (iii) the significant change in serotonin level in the brain influences only the compromise level, or (iv) the significant change in serotonin level in the brain influences neither obsession level nor compromise level. In addition, the levels of obsession and/or compromise influenced by serotonin levels can either increase or decrease. My expectation is option (i) because when obsession levels decrease and compromise levels increase, it indicates two types of behaviors to compromise political differences are both influenced by serotonin.
References:
Arceneaux, K. (2019). The roots of intolerance and opposition to compromise: The effects of absolutism on political attitudes. Personality and Individual Differences, 151, 109498. https://doi.org/10.1016/j.paid.2019.07.008
Carhart-Harris, R., & Nutt, D. (2017). Serotonin and brain function: a tale of two receptors. Journal of Psychopharmacology, 31(9), 1091–1120. https://doi.org/10.1177/0269881117725915
Crockett, M. J., Clark, L., & Robbins, T. W. (2009). Reconciling the Role of Serotonin in Behavioral Inhibition and Aversion: Acute Tryptophan Depletion Abolishes Punishment-Induced Inhibition in Humans. Journal of Neuroscience, 29(38), 11993–11999. https://doi.org/10.1523/jneurosci.2513-09.2009
Lee, M., Jayathilake, K., Dai, J., & Meltzer, H. Y. (2011). Decreased plasma tryptophan and tryptophan/large neutral amino acid ratio in patients with neuroleptic-resistant schizophrenia: Relationship to plasma cortisol concentration. Psychiatry Research, 185(3), 328–333. https://doi.org/10.1016/j.psychres.2010.07.013
Lichters, M., Brunnlieb, C., Nave, G., Sarstedt, M., & Vogt, B. (2016). The Influence of Serotonin Deficiency on Choice Deferral and the Compromise Effect. Journal of Marketing Research, 53(2), 183–198. https://doi.org/10.1509/jmr.14.0482
Richard, D. M., Dawes, M. A., Mathias, C. W., Acheson, A., Hill-Kapturczak, N., & Dougherty, D. M. (2009). L-Tryptophan: Basic Metabolic Functions, Behavioral Research and Therapeutic Indications. International Journal of Tryptophan Research, 2. https://doi.org/10.4137/ijtr.s2129