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Lecture 7

Lecture 7 - Approach & Avoidance (Reward & Defensive Behaviours)

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University of Toronto St. George
Human Biology
John Yeomans

HMB200H1S L7 Jan 31 2012If dont have time to get to safetytry to escape ApproachAvoidance RewardsDefensive detection or fight off preywill try to hidebut Bhvrscats good at seeing moving objects but not colours so safest response is freezinglikely Stimulation of Tectum top of midbrainto be safe stay very quiet stillIf cat closer than have to fight offdepends how strong motivation is to survive and how strong his motivation is to eat youMost animals will stand expose teethclawstell predator there is a cost in fightingPredatorbigger stronger faster but doesnt want damageAutomatic reflex in all vertebratesRats expose claws slad side of cats faceOrient animal in spacecats startle reflex kicks incat freezes for Superior colliculusorganized reflex system by a secondsometimes chance to escapelayerscolumnsComplicated cognitivebhvral assembliesDecisions from intermediate layersLast most desperatestartle reflex only one Approach turns Intermediate layers moderate when used from behindintensity stimuli crossed tectospinal pathAssociated w distance if see predator firstAlso direct input from inferior col auditoryBest activated simply w drop of glutamate into PAGfrom trigeminaltactile systemscome together in parallelregisterTell whether something coming towards headConverge on intermediate layersactivate decisionSimple small stimuliex food in front of animalEyes focus head turns forward sensesmouthbody oriented towardsEx frogsNeed high freq current to stimulate outer tectumUse low intensity to get approach reflexfastBlancharProductstimulating electrodes in animalsdHesslvisualgrasp reflexesalso activated by Glutamate in PAG of Ratsauditorytactile pathwaysBased on retinotopic mapfoveationAvoidance turns Deep layers intense stimuli uncrossed tectopontine path jump fast startle reflexdefensive system to escape predatorsUsually activated by strong electrical stimulation or large stimuli from behindpredatorsDefensive responses PAG glutamate stimuli descending paths for protectiondefenseFrom stratum prefundumPAG below nucleus surrounding the aqueductPAGkeyshapedStimulationcomplex avoidancedefensive responsesStimulate w excitatory glutamateDefensive ResponsesGlutamate used so doesnt spread to other areas vs StartleAvoidance Turnselectrical stimulationactivate neurons wo Defensive ThreatAttackactivating axons that pass thruFreezingAnalgesiaMost common excitatory amino acid transmitterFlightTurn off using muscamal GABA agonist derived Blanchardshow rats respond to cats how mice from poisonous muscaria mushroom like the respond to ratsmuscarin poisonIf rat sees cat coming in from distance most likely Put glutamate on dorsal lateral column of PAGwill run away to safe burrow so cat cant enterdefensive attack immediately assuming threatening stflight 1 if time but prey needs enough time to posture even if no stimuliidentify prey
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