Prefrontal Cortex and Aggression

The area within the frontal lobe at the very front; 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 the term cortex refers to the dense outer layer of the brain.

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regulate our impulsive decision-making and our emotion.

### Aggression:

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Feelings of anger and hostility towards someone or something, often result in violent actions.

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## Analysis

###### *What's the consequence of PFC damage?*

This has been shown partly through studies that show people with prefrontal cortex damage lack the ability to inhibit their impulsive behaviour, may not be able to behave in socially appropriate manners and may be easily provoked into aggression.

## Vietnam Head Injury Study (VHIS) (Grafman et al., 1996)

### Topic: Brain (PFC) and Emotion (Aggression)

#### Intro:

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 the 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.

#### Aim:

Research the impact brain injury has on behaviour, investigating the connections between **frontal lobe damage and the influence this damage had on the aggressive tendencies of the patients**.

#### Procedure:

The Vietnam Head Injury Study (VHIS) is a longitudinal study of over **1,000 American veterans of the Vietnam War**.

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 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.*

#### Result:

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**.

The researchers 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.

#### Interpretation:

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**.

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.

#### Limitation:

* It doesn’t tell us **how** damage to the prefrontal cortex might influence our behaviour.

> Aggression doesn't always lead to aggressive behaviour, the experiment didn't show **how**, only that it **does** affect.
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* Aggression and violence are measured partly using self-report forms, which are the participants’ own answers to the questions.

Self-report of violence and aggression might not be a useful and reliable way of gathering data. People won't always be honest.

* Participants

All white, all male, all from the same war, same way of brain damage.