Chapter 11: AGGRESSION, IMPUSE CONTROL, AND EMOTIONAL DECISION-MAKING Flashcards
Can we say that testosterone automatically increases aggression?
- No not really
- influences behaviour but depends on the context
Can we say that testosterone automatically increases aggression?
- No not really
- influences behaviour but depends on the context
What mechanisms might be responsible for increased aggression?
- testo increases aggression through inhibition
- behavior that would typically be inhibited is not
What effects does castration have on male aggression?
reduces male aggression
Where does testosterone act to promote aggression?
-acts in LS, AMYG and dorsal raphe nucleus
How do rats behave when they are injected testosterone at a fully grown age?
- activational effect of testosterone
- high aggressiveneness
In human research, in what case is the most consistent relationship with T measured?
in competitive interactions rather than self-report
In human research, how does T respond to anger?
T increases physiological response to anger
In humans, when viewing an angry face relative to neutral face, what brain activity is observed?
Resting levels of T correlate
- positively with increased activity in the OrbitoFrontalCortex (the higher level of T. the more activity in OFC)
- negatively with AMYG activity (the higher level of T the lower AMYG activity)
What is the relation between estrogen and aggression?
E signalling influences aggression
What is observed in male mice with disrupted ER?
-reduced aggression
How is aggression in male mice correlated with the number of ER positive cells ?
Positively
Where are the ER positive cells that are correlated with aggression in male mice located?
- LS (lateral septal nucleus)
- BNST (Bed Nucleus of the Stria Terminalis)
- AHA (Anterior Hypothalamic Area)
- not in mPOA (medial preoptic area)
How do male mice who lack etrogen receptor beta behave?
- normal to increased aggression
- depends on social experience or age
In females, what are the organizational effects of androgens, in regards to aggression?
-Prenatal androgens increase aggression
How are aggression levels in female rats influence by the presence of male neighbours in prenatal time?
- When they are in tummy, several of them.
- The more prenatal male neighbours they have in the tummy before they are born, the higher their aggression and T levels.
After being injected Estradiol and testosterone for 14 days, how does the number of fights between female rats evolve?
- Significantly more fight with testosterone injection
- Not that much more fights with estradiol and placebo injections.
According to many studies, how the the activity of serotonergic synapses act on aggression?
it inhibits aggression
Mice lacking a functional serotonin transporter, and exposed to an increase in serotonergic signaling. How do they act?
-less aggressive than wild type mice
Destruction of serotonergic axons in the forebrain. Result?
-Facilitates aggressive attacks
Why is destruction of serotonergic axons in the forebrain presumed to facilitate aggressive attacks?
-Because it removes an inhibitory effect of serotonin
How do monkeys with the lowest 5-HIAA levels behave according to research?
-pattern of risk-taking behavior, including high levels of aggression
Does serotonin simply inhibit aggression?
-No it also exerts a controlling influence on risky behavior
How is reduced serotonin release indicated?
-low levels of 5-HIAA in the CSF
What drugs might help reduce aggressive behavior?
- serotonin agonists
- fluoxetine (Prozac)
What are the two different subtypes of serotonin receptors?
5-HT1aR and 5-HT1bR
What does activation of 5-HT1aR do?
- reduces aggressive behavior
- controls 5-HT tone
How do 5-HT1aR and 5-HT1bR differ in their roles?
-contribute differently in specific brain areas to inhibitory postsynaptic effects of 5-HT on aggression
Where is the 5-HT1b receptor expressed?
-in areas involved in aggression
How does 5-HT1b act on serotonin release?
-acts presynaptically to inhibit 5-HT release.
What’s strange about 5-HT1b activation?
-it inhibits aggression despite decreasing 5-HT (5-HT is supposed to regulate the mood)
What do recent suggestions say that 5-HT1b plays a role in?
- impulsiveness
- rather than aggression
How does 5-HT set tension of the trigger for aggression?
- by limiting impulsivity
- related finding: in pathological aggression, strongly inhibited basal 5-HT tone followed by sharp and brief increase in serotonin
- Aggression occurs, serotonin is inhibited (more aggression) but sudden increase right after (okay pfew let’s calm down)
What does aggressive behaviour require Dopamine wise?
Intact mesocorticolimbic dopaminergic neurons
What can reduce aggression dopamine wise?
- antagonizing Dopamine 2 receptor
- haloperidol does that
What does Dopamine 2 receptor might be mediated by?
-changes in arousal or stress responses
What effect does haloperidol have on locomotion?
-Sedates and impairs locomotion
In rodents, how can GABA activity increase aggression?
-By increasing GABA activity in septal forebrain
How do you modulate GABA receptors for them to influence aggression?
- Allosteric modulation of GABA receptors
- Influences aggression with inverted U curve
What doses of modulatory substance of GABA reduces aggression? (ex: alcohol)
- low and high doses reduce aggression
- moderate doses evoke aggression
During mating season, how will the frequency of aggressive behavior evolve in dominant monkeys relative to subordinate monkeys when they are given alcohol? (relative to control which is no alcohol given, normal state)
- subordinate aren’t more aggressive during mating season when given alcohol
- dominant monkeys are more aggressive during mating season when given alcohol
During nonmating season will the frequency of aggressive behavior evolve in dominant monkeys relative to subordinate monkeys when they are given alcohol?
- subordinate monkeys are a bit more aggressive during nonmating season when given alcohol.
- dominant monkeys are more aggressive (but less than during mating season) during nonmating season when given alcohol.
What kind of drugs can reduce aggression in terms of GABA receptors?
- GABA receptor agonists
- How? By reducing arousal
What reason is there to believe that Norepnephrine is related to aggression?
- related to arousal
- some manip showed NE signalling facilitates aggression
What may be an answer to the doubt about the relationship between NE and aggression?
alpha and beta receptor subtypes contribute differently.
What type of drug can reduce aggression in terms of NE?
- Beta-blockers: beta receptor antagonists
- ex: Propanolol
Do NE alpha2-receptor agonists and antagonists have the same effect?
What doses increase or reduce aggression?
- Yes
- low doses: increase aggression
- high doses: reduce aggression
What is the effect of a2-receptor agonist and antagonist probably due to?
-May be due to shifting dynamics of pre and postsynaptic receptors.
How do mice that cannot produce Nitric oxide behave ?
-persistent fighting despite signals of surrender
In mice, how can aggressive behavior due to inability to produce NO be solved?
- Castration
- Testosterone replacement
In mice, how does no NO influence 5-HT levels?
-lower 5-HT metabolism
In what regions of the brain do mice with no NO have low 5-HT metabolism?
- cortex
- HYP
- midbrain
- cerebellum
How does NO act on aggression in presence of low 5-HT?
acts as a brake on aggression
According to a recent study, what genes could be associated with human aggression?
- variety of genes
- including ones involved in 5-HT and DA signaling
Why are neural circuits of aggression difficult to study?
because these circuits also regulate other social behaviors
What parts of the brain does the social behaviour network include?
- mPOA: medial preoptic area
- LS: lateral septal nucleus
- AHA: anterior hypothalamic area
- VMH: ventromedial hypothalamic nucleus
- PAG: Periaqueductal Gray
- MeA: medial amygdala
- BNST: Bed Nucleus of the Stria Terminalis
Neural circuits of aggression in rodents
slide 46
Neural circuits of aggression in non-human primates
slide 47
What is the vmPFC involved in, in terms of aggression?
-Inhibition of emotional behavior such as impulsive violence or aggression.
How do individuals with vmPFC damage make decisions?
Make decisions without a strong emotional component and select the most practical solution
