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TAMU PSYC 340 - 7 – Extinction and Protein Synthesis Outline

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7 – Extinction and Protein Synthesis OutlineExtinctionCommon Assumptions Regarding Extinction- Two common assumptionso 1. Increasing the proportion of reinforced trials increases learningo 2. You can measure associative strength by looking at the resistance to extinction The stronger the association the longer it takes to extinguish a response What exactly are you looking at? - Answer: - Runway Experiment Based on Trialso Brief experiment description: rat runs down a runway for food Group 1: 20 trials of training Group 2: 30 trials of training Which group takes longest to extinguish? - Answer: group 2 because they had a stronger association, more training- Runway Experiment Based on Reinforcement o Group 1: 100 percent reinforcemento Group 2: 80 percent reinforcemento Group 3: 50 percent reinforcemento Group 4: 30 percent reinforcemento Which group do we expect to take the longest to extinguish?  Answer: group 1o Which group actually takes longest to extinguish?  Answer: group 4o This phenomenon is known as the partial reinforcement extinction effect Theories may be wrong Resistance to extinction is not a good measure of learning- Testing our First Assumptiono Experiment with Panels Phase 1- Black panels: 100%- Gray panels: 0% Phase 2- White panels: 50%- Gray panels: 0% Test- black vs. white Results: rats chose the black panels Suggests that theory is right: greater reinforcement leads to greater associationsThe Discrimination Hypothesis- Why are the animals getting 30% reinforcement taking the longest to extinguish?o Answer: unable to discriminate between regular training trials and extinction trials- Discrimination Hypothesis Experimento Phase 1  Group 1: 100% Group 2: 50%1 Group 3: 100% Group 4: 50%o Phase 2 Groups 1 and 2: get nothing Groups 3 and 4: 100% reinforcemento Test with extinctiono Results: both groups that received 50% training in phase 1 extinguished slower than those that were 100% reinforcedo Suggesting: partial reinforcement led to a kind of learning that preserved through the next phases and produced the PREEFrustration Theory (Amsel)- Theory: partial reinforcement leads to frustration on non reinforced trials, absence of food is US and produces CRof frustration- Pigeon Experimento Experiment description: pigeon is trained to keypeck for grain and is reinforced 100%, other one with white lines is lightly restrained, first pigeon is on extinction training, when first pigeon is on extinction it gets mad and tries to fight second pigeon- Three Properties of Frustrationo 1. It induces driveo 2. Can be conditioned to the environmento 3. It has stimulus properties- What happens to animals that are partially reinforced?o Answer: animal becomes frustrated which is conditioned to the context aka not receiving reinforcement, then they get reinforcement even when they’re frustrated, frustration becomes part of stimulus context, feeling of frustration helps maintain the response Protein Synthesis – Neurobox 9.1Protein Synthesis Reintroduction- Long-term Potentiation (LTP)o Short-term LTP Mediated by: preexisting proteins Lasts: a few hourso Long-term LTP Depends on: protein synthesis- How do we know?o Reason 1: we have evidence of synaptic growtho Reason 2: if you were to block protein synthesis you can block growth and new synaptic connections, if you pretreat aplasia with this drug and block protein synthesis it will not exhibit LTP Drug that blocks protein synthesis: anisomycin Short term not affected by anisomycin Lasts: a day or more Aplysia: 2 weeksProtein Synthesis and Fear Conditioning- Fear Conditioning and Anisomycin2o Group 1: administer anisomycin prior to training, test 24 hrs later Results: they won’t remember fear conditioning, anisomycin blocks CR, disrupts long term memoryo Group 2: administer anisomycin prior to training and test 4 hrs later Results: does not block memory, rat still shows conditioned fear to tone, long term memory needs 24 hrs or longer to develop- Effects of electroconvulsive shocko Electroconvulsive shock can lead to: retrograde amnesiao Train someone and then give shock, they will have no memory of the trainingo Suggests there’s a period of consolidation (4-6 hours) when the memory is laid down and consolidated so it has a lasting effecto Disruption of protein synthesis- Updated Fear Conditioning Experimento Group 1: vehicle (saline) administered immediately after training, test 24 hrs later Results: no amnesiao Group 2: administer anisomycin immediately after training, test 24 hrs later Results: show amnesia, no conditioned fearo Group 3: train, administer anisomycin 6 hrs later, test 24 hrs after training 18 hrs after administration Results: drug had no effect on fear conditioningo What if we microinject the drug directly into the basolateral amygdala? Answer: same results as above- Extinction and Protein Synthesiso Group 1: administer vehicle prior to extinction training and test next day Results: extinction workedo Group 2: administer anisomycin prior to extinction training, test next day Results: disrupted extinction training, still show conditioned fear, drug workingo Group 3: administer anisomycin immediately after training Results: no effect of extinction training, still show conditioned fear, drug workingo Group 4: administer anisomycin 6 hrs after training and test next day Results: show extinction training worked, not respondingo Group 5: administer anisomycin immediately after training and test 4 hrs later Results: extinction still shows effectReconsolidation - Reconsolidation Experimento Phase 1: get mild fear conditioning trainingo Phase 2: present CS alone onceo Phase 3: test long term memoryo What if we microinject anisomycin on the BLA immediately after phase 2? Answer: groups that received anisomycin immediately after re-exposure show significantly less freezing, disrupted long term memory even though it was given after re-exposure and not original training- Reconsolidation general definition: process whereby a previously consolidated memory is placed in a labile state by reactivating the memory traceReconsolidation vs. Extinction- Why does the re-exposure to the CS in Phase 2 not cause extinction?3o Reason 1: there is only one presentation of the CS, extinction requires manyo Reason 2: only established a weak conditioned response at the beginning of the experiment 48A – Reasoning and

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