The Prefrontal Cortex and Aggression PDF

The Prefrontal Cortex and Aggression Since Gage there has been a lot more research into the functions of frontal lobe, especially the area within the frontal lobe called the prefrontal cortex (PFC). The prefrontal cortex is a more specific area within the frontal lobe. It's at the very front of...

The Prefrontal Cortex and Aggression Since Gage there has been a lot more research into the functions of frontal lobe, especially the area within the frontal lobe called the prefrontal cortex (PFC). The prefrontal cortex is a more specific area within the frontal lobe. It's at the very front of the frontal lobe; it's the area of the brain just above the eyebrows beneath the forehead. The term lobe refers to the whole section of the brain, whereas cortex refers to the dense outer layer of the brain. Like Gage's study first suggested, lots of recent research has shown that an important function of the prefrontal cortex is to regulate our impulsive decision making and our emotion. This has been shown partly through studies that show people with prefrontal cortex damage lack an ability to inhibit their impulsive behaviour, may not be able to behave in socially appropriate manners and may be easily provoked into aggression. Studies have also shown that there is a correlation between low functioning frontal lobes and criminal behaviour. (Clark et al., 2008; Blair, 2010) Understanding the biology behind criminal behaviour is a popular and important field of study. British criminologist Adrian Raine has conducted many studies investigating biological correlates of criminal behaviour. He and some of his colleagues carried out a study in 1997 with the aim of comparing the brains of convicted murderers with those of healthy controls (i.e. people who had never been convicted of violent crime). The results showed that there was less activity in particular areas of the brains of the murderers, including less activity in the prefrontal cortex. (Raine, Buchsbaum & Lacasse, 1997) Raine's studies, like many others, can show us that the brains of violent criminals are different to "normal" controls. But it only suggests a correlation and leaves a lot of uncertainty. Another way of studying how the brain can influence behaviour is to find people who have existing brain damage in particular areas of the brain and to compare them with control groups. During the Vietnam War many soldiers received injuries to their brains from a variety of factors (e.g. bullets, explosions, land mines, etc.). The use of brain imaging technology (e.g. MRI -- see section on brain imaging technology for more information) allows researchers to pinpoint the exact location of the damage and to find those participants who have damage in areas of specific interest, like the prefrontal cortex. Aggression: Feelings of anger and hostility towards someone or something, often resulting in violent actions. You can find plenty of information about Phineas Gage online, including one article by the Smithsonian Museum's online magazine. The article is called "Phineas Gage: Neuroscience's Most Famous Patient." The neuroscientist Robert Sapolsky also explains the case of Gage in one of his Stanford lectures (available on YouTube) and he says jokingly, that they take your license away if you don't explain Phineas Gage in an introductory psychology class and I took his warning to heart. If you're interested... 64 Chapter 2: Criminology www.themantic-education.com The Vietnam Head Injury Study (VHIS) is a longitudinal study of over 1,000 American veterans of the Vietnam War that aims to research the impact brain injury has on behaviour. One such report from the VHIS came from investigating the connections between frontal lobe damage and the influence this damage had on the aggressive tendencies of the patients. (Grafman et al., 1996) Based on prior research, the researchers hypothesized that the prefrontal cortex helps exert control over automatic reactions to environmental provocation. In other words, when something makes us emotional, our prefrontal cortex functions to help stop us from reacting in a violent or aggressive manner. To test this idea, the researchers compared Vietnam War veterans who had suffered brain injuries with healthy controls (people with no brain injury). The veterans were also divided into those who had injuries specifically in the prefrontal cortex, and those who had damage to other areas of the brain. MRI machines were used to locate the damage in their brains. The researchers hypothesized that because of the role of the prefrontal cortex in inhibiting impulsive behaviours (e.g. reacting violently to someone who makes you angry) those veterans with damage in the prefrontal cortices would demonstrate more aggression than those with no damage or damage to other parts of their brain. The researchers gathered data on a range of aggressive and violent attitudes and behaviours of the participants using self-report forms (e.g. questionnaires) and family observations. This means they measured aggression by asking questions such as, "How often do you react with physical aggression when someone makes you angry?" (Never, Sometimes, Always, etc.) Or, "How often do you swear or shout at people who make you angry?" Etc. The results showed that those veterans who had damage to their prefrontal cortex had higher levels of reported violence and aggression than the controls or veterans with damage to other parts of the brain. By using MRI technology and being able to compare the three groups in the study, the researchers were able to draw the conclusion that damage to the prefrontal cortex is more likely to lead to aggressive behaviours than no damage or damage to other areas of the brain. Abstraction Extension: Evaluating Methodology: On the surface, it appears this study may show a relationship between prefrontal cortex damage and aggression. But you have to think critically about the methodology. They measured aggression and violence by using self-report forms, which are the participants' own answers to the questions. When evaluating research methods, we have to think about their effectiveness in investigating the specific relationship we're investigating. So in this study, to what extent are self-report of violence and aggression useful ways of gathering data? In studying aggression, would people always be honest? How does the Vietnam Head Injury Study show that damage to the prefrontal cortex may affect aggression? Guiding Question: This is an interesting finding and it's a good basic introduction to the study of the brain and behaviour. However, the issue with this study is that it doesn't tell us how damage to the prefrontal cortex might influence our behaviour: we'll get to that in the next section.