aggression Flashcards
- neural mechanisms of aggression
what is hot blooded aggression
Imaging typically shows that certain brain regions activate alongside specific tasks or experiences, but activation alone does not prove these neurons cause the behavior or experience. Other factors could be contributing, and direct manipulation or more precise measurement is needed to establish causation.
- neural mechanisms of aggression
what is cold blooded aggression
premeditated way of getting what you want eg. Rape, murder.
Case: the moors murders: Ian Brady and Myra Hindley (1963-65): killed 5 children and buried the bodies in saddleworth moors.
- neural mechanisms of aggression
What are the brain regions associated with the limbic system?
Also known as the Papez circuit (1935)
Amygdala
Thalamus/ Hypothalamus
Hippocampus
- neural mechanisms of aggression
What is a key role of the limbic circuit?
Collection of structures in the centre of the brain.
In humans and animals, the amygdala acts as a threat sensor from the environment. in humans there is a positive correlation between how reactive the amygdala is and aggression levels in a n individual.
- neural mechanisms of aggression
What is the limbic circuit also known as?
Papez cuircit
- neural mechanisms of aggression
What are three key regions of the limbic system involved in aggression?
The limbic system is a collection of structures in the centre of the brain. One of its functions is to processes emotional responses such as aggression.
The amygdala has been identified as being linked to the production of aggressive behaviour, FMRI’s show increased activity during aggressive responses. (Gospic)
The hypothalamus has a role in integrating and expressing emotional responses, it can trigger aggressive behaviour as part of the fight or flight response.
These areas of the limbic system communicate with an external layer of the brain, the OFC, controls executive function (decision making) which attempts to control aggression produced by the limbic system.
- neural mechanisms of aggression
What is the link between Kluver & Bucy’s (1937) research in animals and Kluver-Bucy syndrome
Discovered the destruction of the amygdala in a monkey who was dominant in a social group caused it to lose its dominance in the group.
Kluver-Bucy syndrome is a rare neuropsychiatric disorder due to lesions affecting bilateral temporal lobes, especially the hippocampus and amygdala; symptoms include placidity.
- neural mechanisms of aggression
What did Mark & Ervin (1970) report in a patient receiving stimulation to her amgydala?
A woman receiving painless stimulation to her amygdala became enraged and smashed her guitar against the wall.
- neural mechanisms of aggression
Explain the research by Gospic et al. (2011), and how it sheds light on the role of the limbic system in aggression
In this research ppts played ‘the ultimatum game’. Subject a is termed the proposer, subject B is the responder. Subject B was subjected to mild provocation.
The researchers used fMRI to monitor brain activity while playing.
They found that when subject B rejected the offer there was increased response in the amygdala in those subjects.
They also found that when the ppts took Benzodiazepines, which are used to calm anxiety, it halved the number of rejections and decreased amygdala activity.
In conclusion it suggests an association between reactive aggression and the amygdala.
- neural mechanisms of aggression
Explain the relationship between serotonin and aggression.
Ontogenetic: by introducing light sensitive proteins into target cells, researchers can precisely activate or inhibit these cells with light pulses.
Line et al:
They used optogenetics to stimulate the hypothalamus to investigate its role in controlling aggression in male mice.
Activation of this area caused aggressive behaviours, such as attacking other mice and even inanimate objects.
Inhibition of the hypothalamus caused the mices aggressive behaviours to subside
This research provided direct evidence that the hypothalamus (which received connections from the amygdala) is a critical brain region for initiating and regulating aggression.
- neural mechanisms of aggression
What evidence is there for a role of serotonin in violent behaviour?
LIN et al 2011
serotonin has widespread inhibitory effects on the brain - slowing down neuronal activity.
aggression in humans and animals is associated with low levels of serotonin.
normal levels the OFC reduce the firing of neurons and allow for a greater degree of behaviural self control.
decreased levels disturb this mechanism reducing self contrl and inreasing impulse behaviour (including aggression)
- neural mechanisms of aggression
animal studies
LIN et al 2011
Pharmacologically blocking or genetically modifying 5-HT2a receptors. Mice with a deletion of the gene responsible for 5-HT2a expression exhibit less aggressive behaviour compared to typical mice. Stimulating 5-HT2a can lead to aggression, especially when the animal perceives threat or competition.
- neural mechanisms of aggression
anti psychotics
LIN et al 2011
Drugs for schizophrenia block the D2 receptor, but some have impacts on other receptors. Risperidone and olanzapine block the 5-HT2a receptor, and have been shown to reduce aggression in patients with schizophrenia or dementia.
- neural mechanisms of aggression
serotonergic metabolites
LIN et al 2011
Viekunnen et al (1994) compared levels of a serotonin breakdown product (5-HIAA) in the cerebrospinal fluid of violent impulsive and violent non-impulsive offenders. The levels were significantly lower in the impulsive offenders. The levels were significantly lower in the impulsive offenders. This is because the reduction of the 5-H1AA means that there is decreased serotonin activity in the brain which has an effect on controlling impulsive (reactive) aggressive behaviour.
- neural mechanisms of aggression
serotonergic depletion studies
Passomonti et al. (2012) used acute tryptophan depletion (ATD) as a way to temporarily reduce serotonin (tryptophan is the precursor for serotonin). The results showed that ATD reduced connectivity between the PFC and amygdala when participants viewed angry faces, suggesting that oownserotonin might impair the PFCs ability to regulate the amygdala’s response to aggression-related cues.
- neural mechanisms of aggression
- neural mechanisms of aggression
- neural mechanisms of aggression
- neural mechanisms of aggression
- neural mechanisms of aggression
