Lec11 Post Notes PDF

Memory X.Liu PSYC 5130 What is memory? What’s the professor’s name? What did you have for breakfast today? Yesterday? Two days ago? On your first day of 1st grade? When was the last time you went to bed before midnight? How do you drive a car? Play the piano? X.Liu PSYC 5130 Definition… Memory is th...

Memory X.Liu PSYC 5130 What is memory? What’s the professor’s name? What did you have for breakfast today? Yesterday? Two days ago? On your first day of 1st grade? When was the last time you went to bed before midnight? How do you drive a car? Play the piano? X.Liu PSYC 5130 Definition… Memory is the process in which information is encoded, stored, and retrieved. 3R: Registration Retention Retrieval X.Liu PSYC 5130 Memory Types Transient (sec to min) Capacity-limited Information that guides ongoing behavior X.Liu PSYC 5130 ‘permanent’ ‘unlimited’ Information that has been saved across time Long-term memory Declarative(explicit) l Storage and retrieval of material that is available to the conscious mind and (in humans) can be encoded in symbols and language l “I had Cheerios for breakfast Tuesday” Non-declarative(implicit) l Skills and associations unavailable to the conscious mind l Habits, skills, behaviors l Playing the piano, throwing a frisbee, tying your shoes X.Liu PSYC 5130 Neuropsychology: Amnesia Memory loss may manifest itself in two ways: RETROGRADE amnesia – prior to trauma ANTEROGRADE amnesia – following trauma May be a mix, as below: X.Liu PSYC 5130 Trauma to brain Declarative memory--encoding X.Liu PSYC 5130 H.M. X.Liu PSYC 5130 H.M. Right now, I’m wondering. Have I done or said anything amiss? You see, at this moment everything looks clear to me, but what happened just before? That’s what worries me. ——H.M. You'd think it would be impossible to have a relationship with someone who didn't recognize you, but I did. ——Suzanne Corkin X.Liu PSYC 5130 H.M. Lesion Site 1953, at age of 27, H.M. had an operation in which an 8 cm length of the MTL was bilaterally removed cortex, amygdala, anterior 2/3 of the hippocampus X.Liu PSYC 5130 X.Liu PSYC 5130 R.B. Another amnesic patient –Lost his memory after episode during heart bypass surgery (loss blood to brain) –Dense anterograde amnesia (similar to H.M.) –Retrograde amnesia back 1-2 years pre-surgery Upon death several years later, studied brain –MTL appeared intact! –But, careful analysis revealed that within each hippocampus (within the MTL), there were specific lesions X.Liu PSYC 5130 R.B. X.Liu PSYC 5130 Hippocampus X.Liu PSYC 5130 Memory abilities X.Liu PSYC 5130 X.Liu PSYC 5130 Their Memories Are Not Equally Affected Retained the ability to learn procedural tasks. X.Liu PSYC 5130 Hippocampal Profile Working memory is intact Encoding of declarative memory is impaired Storage and retrieval of declarative memory are intact Non-declarative memory is intact X.Liu PSYC 5130 Alzheimer’s Disease X.Liu PSYC 5130 Time to Learn Something Real (NEW)!! X.Liu PSYC 5130 Declarative memory—storage X.Liu PSYC 5130 Memory Consolidation X.Liu PSYC 5130 How and Where memories are stored in the Cortex X.Liu PSYC 5130 Memories are stored as “patterns” There is no Apple neuron vs Orange neuron ‘Apple' Pattern ‘Orange' Pattern ‘Pear' Pattern Brain reactivates patterns of encoding activity during retrieval X.Liu PSYC 5130 Different Memories are stored in different brain regions X.Liu PSYC 5130 Reagh & Ranganath, 2023 Encoding Predictions – fMRI Pattern Similarity Between Encoding and Recall X.Liu PSYC 5130 Recall X.Liu PSYC 5130 AT Network Represents Person X.Liu PSYC 5130 PM Network Represents Context X.Liu PSYC 5130 mPFC Represents Schema X.Liu PSYC 5130 Hippocampus represents episodes X.Liu PSYC 5130 Storage Recent --- hippocampus Remote --- distributed in higher-order cortices X.Liu PSYC 5130 A New Way to Understand Memory – Neural Perspective X.Liu PSYC 5130 The Brain IS Memory Memory is located in every single synapse in the brain There are as many different kinds of memory as there X.Liu PSYC 5130 are neurons and synapses… Two Neural Forms of Memory: Activation vs. Synaptic Changes Optional Reading Activation = Neurons continue to fire action potentials, “remembering” what you were just seeing, thinking Synapses change strength (“weight”) as a result of LTP (learning): this encodes long-term memories that last even after your But when firing stops.. You forget.. activation switches to something new.. X.Liu PSYC 5130 Major Types of Memory Activation-based (sustained neural firing) –Transient, easily lost –Very flexible: mental arithmetic, etc. Weight-based (changes in synapses) –Long lasting, persist over distraction, etc –Very high capacity X.Liu PSYC 5130 STM vs. LTM X.Liu PSYC 5130 Where is Sensory Memory? Surprise! It is just neural firing in sensory brain areas – those neurons just keep on firing away (briefly..) X.Liu PSYC 5130 Where is Short-Term Memory? Surprise! It is neural firing in higher level brain areas that represent specific thing you’re remembering – those neurons just keep on firing away (briefly..) X.Liu PSYC 5130 Where is Short-Term Memory? Extra surprise! And it usually requires contribution from prefrontal cortex – has extra holding power to keep those neurons firing longer! X.Liu PSYC 5130 Where is Long-Term Memory? Surprise! It is in the relevant brain area(s) that encode the specific information! LTM is the sum total of all those synaptic weight changes! X.Liu PSYC 5130 Organization of LTM Episodic = hippocampus Semantic = Neocortex (mostly) X.Liu PSYC 5130 Episodic Memory --- Hippocampus Life is full of interference: where you parked yesterday vs. today vs. last Monday? X.Liu PSYC 5130 Semantic Memory --- Neocortex X.Liu PSYC 5130 Complementary Learning Systems Episodic Semantic X.Liu PSYC 5130 Real Life Task X.Liu PSYC 5130 Classic Lab Task: AB-AC Learn AB paired associates: –window-reason –bicycle-garbage –... Then AC paired associates: –window-apple –bicycle-towel –… X.Liu PSYC 5130 AB-AC Test on AB list: –Window ? –Bicycle ? And AC list: –Window ? –Bicycle ? X.Liu PSYC 5130 Catastrophic Interference Computer Program X.Liu PSYC 5130 Hippocampal System The hippocampus plays a critical role in the rapid learning of new episodic memories. Pattern Separation: overlapping or similar inputs (representations) are transformed into less similar (sparse) representations. X.Liu PSYC 5130 Memory Retrieval X.Liu PSYC 5130 Recall (Test) – Pattern Completion Human memory is content addressable –computer: –human: “Clare, Hiu ** Cha*”?? “Clare, ** ** Cha*”?? “C**, H** ** C**”?? X.Liu PSYC 5130 Trade-off Pattern separation: The system will treat the retrieval cue like a novel stimulus and thus encode a new pattern in CA3, instead of recalling the old one. Pattern completion: The system will reactivate old memories instead of encoding new patternseparated ones for truly novel episodes. Solution: –Hippocampus is fine-tuned –Strategic influences from other brain areas X.Liu PSYC 5130 Complementary Learning Systems Episodic Semantic X.Liu PSYC 5130 Slow Learning Integration Event has a.66 probability of occurring: only with a slow learning rate (.005) does it converge on an accurate estimate across discrete events X.Liu PSYC 5130