FINAL EXAM STUDY GUIDECH. 12 LEARNING AND MEMORYLearning – Relatively long-lasting change in an organism’s behavior (or thought) as a result of experienceTypes of Learning Non-associative learning involves change in the magnitude of response to environmental events–Habituation–SensitizationAssociative learning involves a connection between two elements or events–Classical conditioning–Instrumental conditioningHabituation- Decrease in strength or occurrence of behavior after repeated exposure to stimulusSensitization- Experience of one (startling) stimulus heightens responding to subsequent stimuliLearning with Aplysia Invertebrate learning offers a simpler system in which to isolate neurobiological correlates of learning-Simple nervous system (~20,000 neurons)-Neuronal development hard-wired-Identifiable individual neuronsThe gill-withdrawal reflex occurs when touching the siphon produces a retraction ofthe gillSensitization in Aplysia Shocking the head or tail results in an enhanced gill-withdrawal reflex following siphon touch-Serotonin (interneuron) release promotes enhanced glutamate (sensory neuron) releaseControl Aplysia have ~1300 axon terminals on sensory neuronsAplysia experiencing sensitization have ~2800 terminalsAplysia experiencing habituation have ~800 terminalsClassical Conditioning-An unconditioned stimulus (US) is a biologically relevant stimulus -An unconditioned response (UR) is an unlearned reaction to the US-A conditioned stimulus (CS) is an initially neutral stimulus that acquires the ability to signal important biological events-A conditioned response (CR) is a learned reaction to the CSInterpositus cell activity (PP)-LTP-dependent increase in neuronal firing across trials-NMDA receptor activation leads to changes in synaptic efficacy—i.e., AMPA receptors (which gate sodium) are inserted (LTP) or removed (LTD) from the terminal-LTP-dependent increase in neuronal firing across trials-Neuronal activity in IP corresponds to generation of eyeblink CR, suggesting IP neurons “drive” the behavioral responsePurkinje cell activity-Sole output from cerebellar cortex-Inhibitory: releases GABA onto IP neurons-Decrease in firing rate due to LTD-IP excitation generates CR-Purkinje cell disinhibition enables proper timing of blink CRExtinction of Eyeblink CR- Not simple unlearning- New, opposing response acquired-Learned response is unexpressed- Spontaneous Recovery-CR recovers with passage of time- Renewal-CR is context-specific- Reinstatement-US reminder reinstates CR-Autistics show facilitatory learning in this paradigmEngram- Physical representation of learned information in the brain-Karl Lashley incorrectly concluded that all parts of the cortex make an equal contribution to memory formationEyeblink Conditioning & the Engram-Pons (CS) or inferior olive (US) can be stimulated in place of physical stimulus-The Interpositus nucleus is the brain structure that is sufficient for the CS US learningMemoryLearning is a relatively permanent change in behavior that marks an increase in knowledge, skills, or understandingMemory is the fruit of this learning process, the concrete trace of it that is left in your neural networksAtkinson-Shiffrin Model of MemoryShort Term/Working Memory-Active and temporary representation of information that is maintained for short periods of time-Different systems maintain phonological and spatial-visual information-Central Executive: Monitors and manipulates WM information Baddeley’s Working Memory ModelCentral ExecutivePrefrontal Cortex plays key role in WM- Attention- Places long-term memories into WMDamage results in Dysexective SyndromePerseveration: persist in using old rule despite repeated feedback indicating it no longer holds Long Term MemoryDeclarative or Explicit Memory: memories for facts or eventsNon-Declarative or Implicit Memory: memories for skills, habits, and emotionsRepeated exposure can weaken Episodic Memory; strengthen Semantic MemoryMedial Temporal Lobes & MemoryHenry Gustav Molaison (H.M.): 1926-2008- Two-thirds of medial temporal lobes removed in 1953, including hippocampus, amygdala, and surrounding cortex- Profound anterograde amnesia—able to retain information for only shortperiods of time- Personality unchanged; IQ increased- Memory highly dependent on attentionHippocampus and Explicit Memory-Particular learning tasks in animals can be used to model human declarative memoryAnimal Model of Amnesia-Monkeys with medial temporal lobe damage do poorly on delay non-match to sample (DNMS) taskAnatomy of the HippocampusLTP, Learning, and Memory-Co-occur in structures involved in memory encoding and consolidation-Develops rapidly-Long-lastingAssociativity: only synapses simultaneously active are strengthenedCooperativity: to be sufficiently depolarized postsynaptic neuron must be stimulated at multiple synapses-AP5 blocks induction of LTP and memory of water maze platform NMDA Gene Knock-inDoogie: NMDA receptor altered to stay open longer, allowing more calcium influx, more robust LTP, and enhanced memory Systems/Stages of MemorySystems: sensory, short-term, long-termStages: encoding, storage/consolidation, retrievalNMDA Contextual Memory-Only rats pre-exposed to context can associate shock with contextual representation-NMDA receptors in the hippocampus, particularly area CA3, are required to bind sensory and spatial features of explored environment into single conjunctive representationRetrieval of Contextual Memory-Pattern Completion: because the contextual memory is encoded as a single representation, even a portion of original memory can reactivate entire memoryPlace Cells-How the Hippocampus knows where it is in space-The hippocampus forms a cognitive map of your current space-Place cells in the hippocampus become active when the rat is in a particular place within his immediate environment-Place cells fire relative to extra-maze cues and as the environment moves, the place field adjusts accordingly-During sleep after exploration, the order of hippocampal place cell firing reflects the order in which the cells fired during track runningConsolidation: Process of forming a physical representation of a memory (storing)- Neural trace formed via synaptic plasticity across many neurons and brain regionsRetrieval: Process of accessing stored memories (remembering)Amnesia -Hippocampal damage results in retrograde amnesia, indicating it takes years for memories to be fully consolidatedRetrograde Amnesia