Learning and Memory Summary

Working Memory vs Long-Term Memory

• Working memory: process of using information to address a problem, short-lived (~7 +/- 2 items).
• Long-term memory: stores large amounts of information for extended periods.

Patient H.M. (Henry Molaison)

• Underwent surgery to correct seizures, resulting in profound amnesia.
• Could not form new memories (anterograde amnesia).
• Showed that some learning and memory processes remained intact.

Anterograde vs Retrograde Amnesia

• Anterograde: Amnesia for events after brain injury.
• Retrograde: Amnesia for events before brain injury.
• Medial temporal lobe amnesics typically have anterograde amnesia and temporally graded retrograde amnesia.

Long-Term Memory

• Divided into Explicit (declarative) and Implicit (nondeclarative) memory.

Explicit Memory (Declarative)

• Consciously recalled.
• Includes: Episodic (event) and Semantic (fact) memory.
• Hippocampus is crucial for storing and recalling episodic memories.
• Cerebral cortex serves as the permanent storage site for long-term semantic and episodic memories.

How Hippocampus Stores Memories

• Standard Model: Hippocampus and cortex interact to consolidate and recall memories.
• Over time, long-held memories are stored in the cortex and become independent of the hippocampus.

Spatial Memory and Hippocampus

• Hippocampus is essential for spatial memory.
• Place cells in the hippocampus fire when an animal is in a specific location.
• Neural activity patterns in the hippocampus are replayed during sleep, aiding memory consolidation; disruptions impair learning.

Theories of Hippocampal Function

• Hippocampus involved in declarative/explicit memory and sensitive to conjunctions of events (place + reward).
• Concept cells in the human hippocampus represent information about specific people and things.

Implicit Memory (Nondeclarative)

• Not consciously recalled.
• Includes: Procedural memory, classical conditioning, priming, and nonassociative learning (habituation and sensitization).

Implicit Memory: Procedural Learning

• Knowledge of how to do something, demonstrated by doing it (e.g., motor skills).
• Basal ganglia are critical for procedural learning; cerebellum also contributes.

Summary

• Different types of memory rely on distinct neural systems.
• Hippocampus is essential for declarative memory.
• Skill learning/habits depend on the basal ganglia's dorsal striatum/caudate putamen.