Memory: An Introduction Andrea Mejia and Hana Kuwabara Fall 2016

Goals for Lecture The Legacy of H.M. Defining Memory Loss Subtypes of Memory

Henry Molaison (i.e., H.M.) Pre-operation Uncontrollable Seizures in both temporal lobes  Removed via neurosurgery Post-surgery (H + A +) Controllable seizures Unable to form new memories

Defining Memory: Memory Loss Amnesia Severe memory impairment Usually due to injury or disease Retrograde amnesia Loss of memories formed prior to an event Accidents  disruption of memory consolidation Anterograde amnesia Inability to form new memories (i.e., H.M.)

Defining Memory Short-term memory Long-term Memory Temporary information storage Long-term Memory If short-term memory is rehearsed Enduring memory Extremely large (limitless?) capacity

Subtypes of LTM LTM Declarative Episodic Semantic Nondeclarative (Procedural) Skill learning Priming Conditioning

LTM: Declarative vs. Nondeclarative Declarative memory Memory that can be stated or described Capital of France Nondeclarative (procedural) memory Memory about perceptual / motor procedures Demonstrated via performance (not conscious recollection) Riding a bicycle

Declarative: Episodic vs. Semantic Detailed autobiographical memory 10th birthday party Semantic Generalized declarative memory Facts and information acquired through learning Capital of France Declarative memories are conscious and verbal

Nondeclarative: Skill learning vs. Priming vs. Conditioning Learning how to perform a task by repeating the process May include: Sensorimotor skills (mirror tracing) Perceptual skills (priming) Cognitive skills (rules and strategies) Memories you learn by doing, not transferable by language

Nondeclarative: Skill learning vs. Priming vs. Conditioning Change in how you process a stimulus (e.g., word, picture) because you’ve seen it (or something similar) previously Does not require declarative memory of the stimulus Intact in H.M.

Nondeclarative: Skill learning vs. Priming vs. Conditioning Involves relationships between events Associative learning Classical conditioning Association is formed between two previously unrelated stimuli Pavlov’s dogs Instrumental conditioning (aka operant conditioning) Association is formed between behavior and consequence(s) Skinner box

Neuroanatomy of Memory

Declarative: Formation of Memories Medial temporal lobes (especially hippocampus) Damage: More severe impairments when both temporal lobes removed Do you think hippocampus is responsible for nondeclarative memories? What type of surgery did HM have again? What memory complaints did he display?

Nondeclarative: Skill learning Different areas of the brain Example: Basal ganglia, motor cortex, cerebellum – motor skills Cerebellum – classical conditioning ???? – operant conditioning No specific brain region identified Because so many aspects of behavior involved?

How are memories formed? Iconic memories Briefest memories (a few seconds) From the senses  vision, hearing, smell, touch Short-term memories Slightly longer than iconic memories (~ 30 seconds) E.g., rehearsing a phone number Subtype: Working memory Manipulate info for immediate use E.g., reverse a phone number in your head

How are memories formed? Encoding -- Raw info (sensory channels) transformed into STM Consolidation -- STM transformed into LTM Retrieval -- Stored info brought out of LTM for use **Emotionally arousing experiences are remembered best

STM vs. LTM Hippocampal involvement Effect of head trauma Consolidation of declarative STMs into LTMs Takes years (i.e. HM had retrograde amnesia for two years) Not involved in STM “encoding” or retrieval Effect of head trauma Often causes retrograde amnesia Without affecting older memories May interrupt consolidation of STM to LTM

LTM: Remembering and Forgetting No “upper limit” Forgetting is natural Beneficial to forget some things Filter out unimportant info, free up cognitive resources Memory interference Proactive interference  Previously learned info interferes with learning of new info Retroactive interference  Newly learned info interferes with previously learned info

Memory: Cellular Mechanisms of Memory

Defining learning and memory Change in behavior due to experience (permanent?) Learning vs. memory Learning = information acquisition Memory = storage and retrieval What does learning include?

Simple learning and neural changes Classical (Pavlovian) conditioning Previously neutral stimulus + A response normally generated by another previously learned cue Operant Conditioning Type of learning in which strength of a behavior is modified by the behavior’s consequences Reinforcement (increase the behavior) Positive and negative (adding something and taking something away) Punishment (decrease the behavior)

Habituation Stimulus is presented repeatedly / often Survival value Organism stops responding to it Begins within hours of human life Survival value Ignore stimuli that do not cause irritation or harm Free to attend to other stimuli

Sensitization Opposite of habituation Animal learns to respond vigorously to a previously neutral stimulus Survival value Presence of a noxious or irritating stimulus Animal learns to regard it as dangerous, avoid it

Classical Conditioning (associative learning) Cerebellum may be more involved than hippocampus Unconditioned stimulus (US) Dog food Unconditioned response (UR) Salivation Neutral stimulus Bell ringing Unconditioned stimulus (US) Dog food Unconditioned response (UR) Salivation Conditioned stimulus (CS) Bell ringing Conditioned response (CR) Salivation