emotional behaviour Flashcards
limbic system
- includes forebrain area surrounding the thalamus
- critical for emotion
aggression: context dependent
depends on testing parameters
Sympathetic
stim organs for fight/flight (i.e. heart) inhibit vegetative activities (i.e. stomach)
- acute
Parasympathetic
increases digestion – save energy, prep for later events
Most situations invoke a combination of sympathetic & parasympathetic ie
become alert & inactive, heart rate decrease when danger is present but remote
physiological arousal & emotional feelings:
- spinal cord damage
- pure autonomic failure
- BOTOX blocking transmission at synapses (muscle paralyzation)
- Damaged right somatosensory cortex
- Partly damaged prefrontal cortex
- After damage to spinal cord – similar emotional experiences to before
- Pure autonomic failure: almost no output from autonomic nervous system to body
• No physiological reaction to stressful experience
• normal emotions reported – but less intense - Boltulinum toxin (BOTOX) blocks transmission at synapses & nerve-muscle junctions
• Muscles paralysed – weaker emotional responses - Damaged right somatosensory cortex: normal autonomic response, little subjective experience
- Partly damaged prefrontal cortex: weak auto response, normal subjective exp
- Sudden intense arousal of sympathetic NS without knowing the reason
may experience as emotion i.e. panic attack
- Physiological responses increase feelings (increase in HR – increase both pleasant & unpleasant)
“anger centre”??
doesn’t exist – certain patterns of activation are more closely associated to anger than sadness
- Much of the cerebral cortex reacts to emotional situations
- No brain area appears to be specific for experiencing any particular emotion
- Behavioural activation system
activity of frontal & temporal lobes of L hemi – low to mod auto arousal & approach
- Behavioural inhibition system
increased activity of frontal & temporal lobes in R hemi – increases attention, inhibits action, stim fear & disgust
aggression in hamasters (facing intrusion)
Home hamster facing intrusion:
- First attack of intruder: activity builds up in corticomedial area of amygdala (steroid sensitive)
• Increases probability of attacking the next intruder
- ## stained for an immediate-early gene: c-fos (cell nucleus)
orbital frontal cortex
inhibits action in medial amygdala
Aggressive, violent, antisocial behaviour depend on both environment & genes
- Env: childhood abuse, witness violent abuse b/w parents, live in violent neighbourhood, lead exposure
- Heredity : significant for aggressive behaviour but depend on how to measure
Genetic + environment effect on aggression: gene controlling enzyme monoamine oxidase A (MAO A) + bad environment
MAO A : an enzyme in synapse that breaks down/metabolize monoamines – some of serotonin/ dope/ norepi after reuptake
• Low activity (short form of gene) – less MAO A enzyme produced + bad childhood – link to aggression, less resilience (greater emotional reactivity?)
• Effect of gene depends on previous experience (increase aggression only in ppl with troubled childhood)
gene x env interaction
low serotonin (5HT) release (indicated by? & associated with?)
- Serotonin levels in neurons: fairly constant (neurons reabsorb most serotonin released & synthesize enough to replace the amt washed away)
measure instead: - serotonin metabolite levels (serotonin turnover) – concentration of 5-HIAA in extracellular space/ CSF - low metabolite levels associated with aggressive behvaiour & impulsiveness
- mice: social isolate increases aggression & decreases 5-HIAA levels)
twin aggression studies
mono twins resemble each other much more than dizygotic twins - violent & criminal behaviour
- adopted children resemble biological parents
humans – DHEA is inert
secreted by adrenals & converted into active sex steroids (T & E2)
- does not have its own receptors, not synthesized directly, antiglucocorticoid effects
hyp: same for T in song sparrows during non-breeding season? since T is not detected in blood plasma & gonads shrink
finding: enzyme 3 beta-HSD is upregulated in non-breeding season (increases capacity for local production of T), low in breeding season
hormonal effects on aggression
- Same age: those with higher T levels on avg tend to be more aggressive (both M & F)
• But differences are small
Hypothesis: aggressive behaviour depends on a sudden burst of T in response to an event (not baseline)