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Chapter 35 Learning and Memory Learning The acquisition of knowledge or skill Types of learning • Non-associative – Habituation, sensitization • Associative – Classical conditioning – Operant Conditioning Nonassociative No paired stimulus/response – habituation • • repeated exposure to a stimulus results in reduced responding to that stimulus generally neutral, non-noxious stimuli – sensitization Associative Paired stimulus/response – classical conditioning (two stimuli are paired; when the light shines ----- get food) – operant conditioning (stimuli and response are paired; push lever = food Classical Conditioning Conditioned stimuli (no overt response) and unconditioned stimuli (gives an overt response) – not simply timing of events relative to each other – we can detect a positive correlation between two stimuli (efficiency of pairing) – Extinction can occur over time (unpaired) Operant conditioning trial-and-error learning – A predictive relationship between response and a stimulus – behaviors that are rewarded tend to be repeated – those that cause aversive consequences are not repeated – timing is important – must have predictive element Learning involves forming memories II Memory storage and retrieval of information 1. Stages of Memory Short-term memory and long-term memory – Short-term memory (STM, or working memory) – a fleeting memory of the events that continually happen – lasts seconds to hours – limited to 7 or 8 (not more than 12 items) pieces of information Long-term memory (LTM) – has limitless capacity – can be blocked by blocking protein synthesis Transfer from STM to LTM Factors that affect transfer of memory from STM to LTM include: – Emotional state – we learn best when we are alert, motivated, and aroused – Rehearsal – repeating or rehearsing material enhances memory – Association – associating new information with old memories in LTM enhances memory – Automatic memory – subconscious information stored in LTM 2. Declarative (Explicit) or Nondeclarative (Implicit) Memory Declarative(explicit)memory • Knowledge we have conscious access to • Episodic (情景式) • Personal experiences / events etc. Canoeing on Lake Winnipeg, surfing in San Diego • Often referred to as autobiographical memory • Semantic (语义式) • Conceptual knowledge “Where is Lake Winnipeg, where is San Diego?” “How do you canoe, how do you surf?” Declarative (Fact) memory: –Entails learning explicit information –Is related to our conscious thoughts (有意 识的思维) and our language ability –Is stored with the context in which it was learned Nondeclarative or Implicit Procedural learned skills or habitual responses Skill memory – – – less conscious than fact memory and involves motor activity acquired through practice do not retain the context in which they were learned Structures Involved in Fact Memory Fact memory involves the following brain areas: – Hippocampus and the amygdala (杏仁核) – Specific areas of the thalamus and hypothalamus – Ventromedial prefrontal cortex and the basal forebrain Figure 15.8a Major Structures Involved with Skill Memory Skills memory involves: – Corpus striatum – mediates the automatic connections between a stimulus and a motor response – Portion of the brain receiving the stimulus (visual in this figure) – Premotor and motor cortex Figure 15.8b 3. Mechanisms of Memory Changes that take place during memory include: – Neuronal RNA content is altered – Dendritic spines change shape – Unique extracellular proteins are deposited at synapses involved in LTM – Presynaptic terminals increase in number and size, and release more neurotransmitter 4. Forgetting • Decay theory •memory fades away with time, unless there is rehearsal • Interference theory •memory for other material interferes with information we are trying to remember Decay Theory of Forgetting • Memory fades away with time • unless there is rehearsal Rehearsal Amount of information 100% Day 1 Day 2 Day 7 Day 30 • Example: reviewing notes after class Forgetting as a result of interference Retroactive (逆行性) Interference Proactive (顺行性)Interference Retroactive Interference Current learning interferes with recall of previously learned material Learn A Time Learn B Memory Loss for A Proactive Interference Prior learning interferes with retention of new information Learn A Time Learn B Memory Loss for B 5. Retrograde and Anterograde Amnesia (失忆症) Time Retrograde Anterograde Head Trauma 《Random Harvest》(1942) 《鸳梦重温》 导演:Mervyn LeRoy 编剧:James Hilton 主演:Greer Garson Ronald Colman