Social Perception and Rage and Agression

Lecture 18 

Processing facial identity 

  • FFA (fusiform ventral gyrus) in ventral occipitotemporal cortex

  • Part of identity- things that dont change 


Processing facial expression 

  • STS superior temporal sulcus in temporal lobe

    • Feeds to amygdala to decide if there is a threat 

  • Responds to any type of biological motion 

  • In monkeys: 

    • STS (expression) and area IT (identity) 

  • Difference in humans and monkeys have to do with visual cortex areas 

    • Have extra cortex that has pushed visual areas like area IT a nd displaced it underneath the brain 

    • Expansion of temporal lobe due to language 


Facial symmetry 

  • Symmetry may indicate phenotypic quality and how well an individuals genome can resist disease and maintain normal development in the face of environmental perturbation 

    • If soeone is attrcated to symmetric face theta re attracted to underlining genetic quality of the person with the symmetric fae 

  • Testosterone and estrogen during puberty affect the face anatomy 


Health and attractiveness 


Mesolimbic DA and attracitiveness 

  • When people see attractive person it activates mesolimbic DA reward 

    • NA and MOFC , makers attractivenessa rewsarding 

Lecture 19 rage and aggression 


  • Testosterone - motivates the pursuit and defense of btoh mates and social status 

    • Only facilitates aggression when aggression is a path to sical status 

    • Often related to competition for social status 


Female reproductive development 

  • Gonads develop into ovaries 

  • Mullerian ducts develop 

    • Fallopian tube 

    • Uterus 

    • Cerix 

  • Wolffian ducts regress 

  • Prenatal ovarian hormones are not involved in this process 

  • External reproductive system is also differentiating: 

    • Clit, labia, vagina 


Male reproductive development 

  • At about 6 weeks, TDF (testes determination factor) gene on Y chromosome causes gonads to develop into testes 

  • Testes produce etstosterone starting at about 8 weeks, peaking at 14 weeks 

    • Levels then decline until second peak 2 months after birth 

    • Low levels until puberty 

  • Wolfian ducts develop 

    • Vas deference 

    • Seminal vessicle 

    • Prostate gland 

  • MIH from testes causes regression of mullerian ducts 

  • Process of masculinizing internal reproduction system structure is dependent of gonadal hormones 

  • External genitalia - dependent on dihydrotestosterone 

    • Penis and scrotum 


Steroid hormones makes neurons grow 

  • Testosterone and estrogen promote neuritic growth in cultured hypothalamic neurons from newborn mice 

    • Changes anatomy of the brain 


SDN POA in rats 

  • The sexually dimorphic nucleus of the preoptic area of the hypothalmus (SND-POA) is five times larger in male vs female rats 

    • Organizational effects of T 

  • Give female rates testosterone, will develop male sized SDNPOA 

  • Castrate male rates (no more T) will develop female sized SDN POA 


Mouse aggression depends on both organizational and activational effects of testosterone 

  • Female mice show male levels of aggression if (have to do both) 

    • Exposed to testosterone on first day of life (organizational effects/ changes brain anatomy) 

    • Given testosterone as adults (activational effects) 

    • Testes acts later in life that presumably acts in neural circuitry that was organized earlier by testosterone (activating what was already there) 


Organizational effects of T on aggression 

  • Male monkeys show more rough and tumble play as juveniles 

  • Exposing female fetuses to testos in utero increases rates of rough and tumble play 

  • Blocking androgen (what testos binds to)  receptors in male fetuses in utero decreases rough and tumble play 

  • If woman was having trouble with pregnancy dr will prescribe progesterone which maintains the lining of uterus 

    • Progestorone also binds to and activaets androgen receptor (acts like testos in utero) 

    • Babies developing would be exposed to testos 

    • These babies had a higher score of aggression when compared to unexposed siblings 


Activational effects of T on aggression 

  • During mating season, rhesus macaques show 

    • Increased testes size 

    • Increased plasma testos concentrations 

    • Increases muscle mass 

    • Increased ratesof aggression 

    • Association between high levels of aggression and testos 

  • Relationship between T and aggression is bidirectional 

    • Physiological injections of T exaggerate existing patterns of aggression 

      • Promssive effects 

    • Aggression can affect T 

      • Aggression can cause increase in T 

      • Winning vs losing 


Activation effects of T on human aggression 

  • As levels of T in adulthood increase aggressive behavior in adulthood 

  • Higher t in violent vs nonviolent male and female cirminals 

  • Correlates with response to provations 

    • Ultimate game - when you choose to reject, you re punishing other person (aggression) 

    • Linked testos to decisions made in game 

    • Rejected - higher T levels 

  • Some studies fail to find associations between t levels and aggression in humans 

    • Might be bcecause T is more about motivating people to compete for social status. Path for status doesnt really come from aggression in humans 

    • About maintenance and pursuit of status than aggression. For animals the way to get status is through aggression 

  • Overall, a weak but significant association 

  • T may be more directly related to the maintenance and pursuit of social status 


Neurological effects of T 

  • Cells that bind to T in monkeys are concentrated in: (regions gave a lot of cells that have androgen receptors 

    • Midbrain (PAG) 

    • Hypothalamus 

    • Amygdala 


Defensive rage circuit in the domestic cat 

  • Electrical stimulation of midbrain (PAG), medial hypothalamus, or maygdala produce affective aggressive response 

    • Growling, hissings, piloerection 

    • Back arch 

    • Paw strike 

  • Stria terminalis links amygdala and hypothalamus 

    • T increases firing frequency if it is already firing 

    • Stria - white matter pathway where bunch of different neurons send their axons down with same connection 

    • Ation potentials travel down those axons during rage response 


T and the amygdala response to threatening faces 

  • If have higher T, have stronger amygdala response 

  • The more active the orbital frontal cortex was, the less likely they were to reject unfair offer and have aggressively 

  • At the medial frontal cortex, T inhibits it (releases control of MFC and amygdala) and get more aggression) 

  • MFC helps restrain the amygdala and regulate it (inhibitory effect on amygdala 


Serotonin 

  • There are nuclei of serotonin neurons that send axons throughout the brain and release serotonin in manu different parts of the brain 

    • Called raf a nuclei 


Serotonin and aggression in free ranging rhesus macaques 

  • Capture monkeys and take sample of cerebral spinal fluid sample which tells you about the brain 

    • Within sample of spinal fluid can measure metabolite of serotonin 

  • Low CSF 5 HIAA (metabolite of brain serotonin) is associated with 

    • Severe unprovoked aggression 

    • Deficits in impulse controls 

  • Serotonin has imposing effects to T 

  • High T / lwo 5 HIAA associated with highest rates of aggression 

    • T provides competitive drive 

    • Serotonin regulates the threshold for aggression 

    • Testos provided competitive drive/mtoivation and serotonin regulated the threshold for aggression 

    • Low serotonin, low threshold to respond aggressively 


Neural circuitry of emotion regulation 

  • Men with damage to OFc are more likely than men with damage in other brain regions to have outburst of rage at family members, friends, and colleagues (lost impulse control) 

  • Serotonin agonists increase glucose metabolism in OFC 

  • This increase is blunted in patients with aggressive impulsive personaility disorders 

  • There are lots of serotonin receptors in OFC may act there to inhibit aggression 

    • Serotonin might act opposite of T, control limbic system response 


MAOA allele and aggression 

  • Monoamine oxidase enzyme 

    • Clears away excess NT from synapse, breaks down monoamine NT (DA, epinephrine, serotonin)

  • Evidence: 

    • Large dutch kindred with MAOA mutation with persistent and extreme reactive aggression in some males 

    • Male MAOA knockout mice are hyperaggressive 

    • Men with L allele of MAOA are more prone to impulsive violence, particularly if they were abused as children 

      • Exampels of egen by environment interaction - gene more likely to have an affect when combined with certain aharacteric of environment 


OT and maternal aggression 

  • We see mothers aggressively defending offspring 

  • OT facilitates her not being overcome by fear and anxiety so she can face predator (lots of OT from birth) 

    • OT decreases firing rates of neurons in amygdala (which has anxiolatic/ relaxing effects)