Memory: An Introduction Andrea Mejia Spring 2017

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 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 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 Consolidation of declarative STMs into LTMs Takes years (i.e. HM had retrograde amnesia for two years) Not involved in STM “encoding” or retrieval

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