Brain Structures involved in Risk-Taking
Evolutionarily speaking, humans, as a species, may long have possessed a risk-taking personality (Zuckerman, 2000). Being risk-takers, our ancestors have been able to survive and pass on their genes to their offspring. Their primary means of survival, which is hunting for wild animals for food, and also their means for propagating their genes, mating, are examples of risky behaviors manifested by humans of centuries ago. However, despite our innate nature of being risk-takers, individuals differ in their levels of risk-taking trait, believed to be a function of heredity.
According to Zuckerman (2000), the sensation-seeking trait which encapsulates the risk-taking behaviors, is 60% genetic –higher than the average, which points to 30% to 50%. But aside from genetics, he also mentioned that other factors which might affect a person’s level of risk-taking are the biochemistry of neurotransmitter systems and the structure and function of the brain. Brain structures There has been a significant amount of research covering the relationship of various areas of the brain with risk-taking behavior.
Most of them have identified particular brain structures as being connected with the persistence of risky behavior in humans. The primary structures that have been identified are located in the Frontal and Parietal lobes, suggesting the involvement of working memory and imagery in the selection process, respectively. Risks were found to produce higher activation than certain alternatives in both of these lobes (Gonzalez et. al. , 2005). This indicates that considerably more cognitive effort is involved in the selection of a risky gain than that of a guaranteed one.
In particular, structures such as the: (1) inferior pre-frontal cortex (Paulus et al. , 2001), (2) nucleus accumbens, (3) orbital frontal cortex, (4) the insula (Critchley et al. , 2001), (5) the ventrolateral and ventromedial frontal cortices (Elliott et al. , 1999; Rogers et al. , 1999; Elliott et al. , 2000), (6) the amygdala (Trepel, et al. , 2005), (6) the anterior cingulate cortex (Elliott et al. , 2000), and the (6) parietal cortex (Paulus et al. , 2001) have been reported to be activated in studies on risk-taking.
The pre-frontal cortex, located in the frontal lobe, was found to affect the estimation of future outcomes and appraisal of risky choices. Significant prefrontal activation was observed in many other risk-taking studies (Ernst et al. , 2002; Paulus et al. , 2003; Krain et al. , 2006; Van Leijenhorst et al. , 2006). The dorsolateral pre-frontal cortex, in particular, was found to be responsible for a person’s ability to plan for future actions –a required step in a decision-making task under a risky situation. On the other hand, the ventromedial prefrontal cortex has another specific function in decision-making under risk.
This area of the brain is activated when the person faced with a risky decision-making task anticipates losses in the said task (Trepel, et al. , 2005). However, this area may be less influential than another area identified, the nucleus accumbens (located in the brainstem), in terms of evaluating reward (Galvan et. al. , 2006). This area of the brain was found to be correlated with subsequent risk-taking behaviors since the activation of the nucleus accumbens is consistent with the idea that risk-taking behavior may be reinforcing.
This is due to the findings that anticipation of risky outcomes activates reward-related systems (Kuhnen & Knutson, 2005). The amygdala, on the other hand, is also responsible for emotion and learning (Trepel, et al. , 2005). It is one of the areas that influence reward processing in risk-taking tasks (Steinberg, 2007). According to Trepel (2005), people who have lesions in this structure are more prone to choose the option which entails more risk.
This is because the amygdala is shown to be an essential structure in the anticipation of losses in a risky decision-making situation. The right insula was observed to have significantly stronger activation in subjects who selected a risky response in a risky-gains task. In addition, the degree of activation of the insula was correlated to the probability of selecting a safe response after a punished response. The degree of harm avoidance and neuroticism of the subjects’ affected the activation of the insula as well (Paulus et. al. , 2003). Objectives of the Study
This research study aims to demonstrate the differences in activation in the brain structures of people from different developmental stages and genders while perceiving or engaging in a risky behavior using an fMRI imaging technique. Also, the participants’ risk-taking behaviors will be assessed through a scale and the results will then be compared with those of the results of the fMRI scan. The researchers would also like to determine if there are certain brain structures that have developed further because of individuals heightened tendency to engage in risky decision-making.
It is hypothesized that results of this experiment will be similar to the findings of the previous researches, that the prefrontal cortex and other associated regions would be the areas responsible for risky decision-making. Also, it is assumed that there would be differences based on the participants’ ages, when it comes to risk-taking trait and that these differences would also manifest in the development of the certain brain parts responsible for their behavior. For the people assessed as risk-takers, those areas that are responsible for their increase in risk-taking behavior are more developed than the other parts of the brain.
METHODOLOGY Participants A total of 18 participants will take part in this experiment. This will comprise of six adolescents (age 7-11), six young adults (age 21-29) and six middle-aged adults (age 38-50). Each group will be further composed of three males and three females. Adolescents are defined as participants aged 7 to 11, while adults are those aged 23-29. Subjects would be screened to make sure that they have no history of neurological or psychiatric disorder. Adolescent participants will be volunteers from the Psych 101 subject pool while the adult participants will be volunteers from internet advertisements sent by the researchers.
Participants below 18 years old would be required to have their parents’ consent before participating. Materials Cognitive Appraisals of Risky Events Scale (CARE). The CARE is a 30-item self-report measure that consists of six factor-analytically derived scales that represent six categories of risk-taking behavior (Fromme, Katz, & Rivet, 1997; Appendix B). Its scales involve (1) Illicit Drug Use, (2) Aggressive/Illegal Behaviors, (3) Risky Sexual Activities, (4) Heavy Drinking, (5) High Risk Sports, and (6) Academic/Work Behaviors.
The CARE uses a seven point Likert scale (1=not at all likely; 7=extremely likely) to rate three types of outcome expectancies: (1) Expected Risk (ER) or likelihood of a negative consequence, (2) Expected Benefit (EB) or likelihood of a positive consequence, and (3) Expected Involvement (EI) or the likelihood of engaging in the activity in the next six months. The CARE has also been used to assess participation in prior risk-taking behavior (Katz et al. , 2000). Risk Perception Questionnaire.
The risk perception questionnaire will measure the risk perception or the perceived adverse consequence and risk preference which describes whether one believes the benefits inherent in an activity outweigh the costs, or vice versa (Gardner & Steinberg, 2005). Along with the CARE, participants will be asked to rate the risk involved in engaging to these behaviors. For each scenario, the participants will be asked to provide a rating from 1 to 7: (1) If you did this activity, how scary are the things that could happen?
(1 = Risks are not scary at all; 7 = Risks are very scary); (2) If you did this activity, how much are you at risk for something bad happening? (1 = I would be very much at risk; 7 = I would not be at risk); (3) How would you compare the benefits (or pleasures) of this activity with the risks (1 = Risks much greater than the benefits; 4 = Risks equal the benefits; 7 = Benefits are much greater than the risks); (4) If something bad happened because of this activity, how serious would it be? (1 = Not at all serious; 7 = Very serious).
The higher the ratings for each scenario would mean higher risk and risk perception for the behavior to elicit. Procedure – Pretest The aim of the pretest is to come up with one highly representative scenario for each of the six domains of risky behaviors used in the study of Fromme, et al (1997). After consolidating as much scenarios possible of risk taking in coordination with the domains from literature, the researchers will administer a pretest mechanism to figure out which scenario to use for the fMRI part of the experiment.
A very brief pretest form will be given to the participants asking the scenarios that come to mind when they imagine each of the six domains. The question for the preliminary form will be very direct and open-ended in questioning. This pretest sheet will be administered to at least 50 adolescents, 30 young adults, and 30 middle-aged adults – different from the pool that the researchers will use for the fMRI part. Once all data are consolidated, the researchers will determine the central themes that are used to depict any of the six domains.
The central themes that come up will be used as the scenarios that will be read aloud for the participant when they become asked to appraise different risk-taking situation during the fMRI task. Procedure – Experiment A brief introduction to the research will be given to the participants. The participants will then be asked to fill up a written consent form. The participants will be asked to be tested in the Clinical Neuropsychology Research. They will be led to a private room and, after giving out informed consent and completing a demographic questionnaire.
When the participant enters the experiment area, he or she will be asked to complete the Cognitive Appraisal of Risky Events Scale (CARE) (Fromme, Katz & Rivet, 1997) with the Risk Perception Questionnaire. The participants will be asked to rate the following factors: Risky Sexual Behavior, Heavy Drinking, Illicit Drug Use, Aggressive and Illegal Behaviors, Irresponsible Academic/Work Behaviors and High Risk Sports in terms of expected risk, expected benefit and expected frequency of behavior. After the pen and paper part of the experiment, the participants will then be asked to schedule an fMRI.
They will be asked their contact numbers so that the researches can remind them of the schedule for their interviews. The researchers will ensure that confidentiality and anonymity will be granted for the participants of the experiment. During the fMRI session proper, the researchers will explain thoroughly the process that they will go under. Each participant will be asked to take off all metal accessories that they may have because it might disrupt the data that will be collected by the machine, both seen at the Appendix at the end of this proposal.
They will also be asked to wear a hospital gown when they go under the fMRI machine. They will be instructed that they must avoid movement because it might also disrupt the data that would be collected. Once inside the fMRI machine, the researchers along with licensed medical practitioners will give instructions to the participant via microphone in an adjacent room filled with the controls for the machine. The researchers will narrate the scenarios which were found to be most fitting according to the pretest and then ask the participants to think of what they will do in those situations.
So that the researchers are assured that the participants will really appraise the tasks, they will be told that they must know their answers fully after being inside the machine because they will be asked to explain them to a panel. They will also be given two minutes for each situation to think about what they will do. Six situations will be presented, each will reflect the domains of risk-taking as provided by literature. During the time given for them to think, the machine will take images of their brain.
As what research claims as optimal (Horwitz, 2000), images will be taken 2-3 mm apart for every 5-7 seconds to maximize spatial and temporal resolution respectively. This aims to see which brain areas are used when thinking about what they would do in risky situations. After the images of brain activation are taken using the fMRI, the participants will be briefed fully on the nature of the experiment. At the end of the experiment, the data from both the questionnaire and the fMRI images will then be assessed for analysis.
The researchers will try to determine whether the results from the self-report translate to the activation of certain brain parts that have been found to take part in the decision making process of risk taking and appraisal. The areas that the researchers will look out for are orbito-frontal cortex, the prefrontal cortex, the nucleus accumbens. The insula, the ventrolateral and ventromedial frontal cortices, the anterior cingulated cortex and the parietal cortex. Supporting structures like the calcarine sulcus, precuneus, thalamus, cingulated gyrus and superior temporal gyrus will also be closely observed for activation in the brain image.
The data will then be compared to the responses of the participants in the CARE scale and the Risk Perception Questionnaire. The cumulative score of each participant should correspond to the brain areas that are hypothesized to be related to the decision making processes involved in risk taking behaviors like the prefrontal cortex (for estimation of future outcome), the nucleus accumbens (for the activation of reward-related system during risky-gains situation), the right insula (for harm avoidance and risk appraisal).
