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AGGRESSIVE BEHAVIOR

BY

Prof. em. Yasmeiny Yazir.

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Aggressive behaviorAggressive behavior

Involve threatining

- gestures or actual

- attacks directed toward

Is species typical

- organized by neural circuits, whose

development is largely programmed

by an animals genes

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Many aggressive behavior s are related to reproduction.

Other aggressive behaviors are related to self defence ( an

animal threatened by a predator ).

Can consist of actual attacks or simply threat behaviors,which consist of postures or gestures, that warn the

adversary to leave or it will become, the target of an attack.

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The threatened animal may show :

> Defensive behaviors.

> Threat behaviors or an actual attack

against the animal that is threatening it.

> Submissive behaviors ( accept defeat and

will not challenge the other animal.

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In the natural environment most animals display for

more threats than actual attacks, they have the

advantage of not involving actual fightingwhich can

hard one or both of the combatants.

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Attacking a member of the same speciesAttacking a member of the same species high activity of thehigh activity of the

sympathetic system.sympathetic system.

Attack of a predatorAttack of a predator more cold blooded efficient and no highmore cold blooded efficient and no high

activity of the sympathetic system.activity of the sympathetic system.

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Neural control of aggressive behaviors :Neural control of aggressive behaviors :

-- The periaqueductal gray matter is involve in defensive behavior andThe periaqueductal gray matter is involve in defensive behavior and

predation.predation.

-- These mechanisns are modulated by the hypothalamus andThese mechanisns are modulated by the hypothalamus and

amygdala.amygdala.

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Activation of the central nucleusActivation of the central nucleus inhibits defensive aggression,inhibits defensive aggression,

stimulation of basolateral or medial, amygdala stimulates it stimulationstimulation of basolateral or medial, amygdala stimulates it stimulation

of the medial hypothalamus also facilitates defensive aggression, butof the medial hypothalamus also facilitates defensive aggression, but

through inhibitory connections with the lateral hypothalamus, inhibitsthrough inhibitory connections with the lateral hypothalamus, inhibits

predation.predation.

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Activity of serotonergic neuronsActivity of serotonergic neurons inhibit risk taking behaviors, includinginhibit risk taking behaviors, including

aggression.aggression.

Low CSF levels of a metabolite of serotonine are correlated withLow CSF levels of a metabolite of serotonine are correlated with

increased risk taking and aggressive behaviors in monkeys andincreased risk taking and aggressive behaviors in monkeys and

humans.humans.

Alcohol increase, aggression in some people, research suggests thatAlcohol increase, aggression in some people, research suggests that

the effects of this drugs can be opposed by those of serotonin.the effects of this drugs can be opposed by those of serotonin.

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Hormonal control of aggressive behaviorHormonal control of aggressive behavior

Many forms of aggressive behavior are controlled ( affected ) byMany forms of aggressive behavior are controlled ( affected ) by

hormones especially sex steroid hormones.hormones especially sex steroid hormones.

Androgens primarily affect, defensive attacks, they are not necssary forAndrogens primarily affect, defensive attacks, they are not necssary for

defensive.defensive.

Behaviors which are shown by females as well as males.Behaviors which are shown by females as well as males.

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In males androgens have organizational and activational effects onIn males androgens have organizational and activational effects on

offensive attack, just as they have on male sexual behavior.offensive attack, just as they have on male sexual behavior.

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Androgens apparently promote aggressive behavior in humans, but it isAndrogens apparently promote aggressive behavior in humans, but it is

difficult to study this topic in our species.difficult to study this topic in our species.

Differences in testoterone levels, have been observed in criminals withDifferences in testoterone levels, have been observed in criminals witha history of violence.a history of violence.

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Research suggests that the primary effect of androgen may be toResearch suggests that the primary effect of androgen may be to

increase motivation, to achieve dominanceand that increasedincrease motivation, to achieve dominanceand that increased

aggression, may be secondary to this effect ( cannot be sure , whetheraggression, may be secondary to this effect ( cannot be sure , whetherhigher androgen levels promote dominance or whether succesfullhigher androgen levels promote dominance or whether succesfull

dominance increases androgen levels.dominance increases androgen levels.