Lecture Notes on Memory and the Hippocampus

Introduction

• Hippocampus plays an essential role in memory.
• Henry Molaison (H.M.): Case study of significant memory deficits post-hippocampus surgery for seizure treatment.

Learning Objectives

1. Understand encoding, storage, retrieval processes in memory.
2. Differentiate types of memory: sensory, short-term, long-term.
3. Analyze long-term memory organization models.
4. Evaluate factors affecting memory retrieval.
5. Recognize memory distortion, forgetting, and false memories.
6. Identify biological correlates of memory.

Memory: Definition and Importance

• Memory: Ability to retain knowledge, crucial for adaptive behavior.
• Adaptive Advantage: Memory helps in quick responses to environmental challenges (e.g., predator avoidance).

Memory Metaphors

• Memory likened to wax tablet: Impressions are memories that can fade or remain.
• Computer analogy: Data entered, stored, retrieved; unlike computers, brains reconstruct memories.

Memory Processes

1. Encoding: Acquiring information into memory.
2. Storage: Retention of information.
3. Retrieval: Accessing stored information.

Models of Memory

• Atkinson-Shiffrin Model: Info flows through stages, from sensory to short-term to long-term memory.

Sensory Memory

• Brief, holds large amounts of sensory data.
• Types: Visual (iconic), auditory (echoic), and touch (haptic).

Short-Term Memory

• Lasts ~30 seconds without rehearsal.
• Capacity: 5-9 items, improved by chunking.

Working Memory

• Active manipulation vs. passive storage in short-term memory.
• Components: Phonological loop, visuospatial sketch pad, central executive.

Long-Term Memory

• Unlimited capacity and duration.
• Elaborative rehearsal: More effective than simple repetition.

Types of Long-Term Memory

• Declarative (Explicit): Semantic (facts) and episodic (personal experience).
• Nondeclarative (Implicit): Procedural (skills), priming, conditioning.

Memory Retrieval

• Involves cues and context.
• Encoding Specificity: Context and state cues aid retrieval.

Forgetting

• Decay: Memory fades over time.
• Interference: Proactive (old info) and retroactive (new info).
• Blocking: Tip-of-the-tongue phenomenon.

Biological Basis of Memory

• Synaptic changes: Long-term potentiation (LTP) crucial for memory.
• Brain structures: Hippocampus (declarative memory), basal ganglia (procedural memory).

Improving Memory

• Distributed Practice: Better than cramming.
• Sleep and Exercise: Aid in memory consolidation.
• Mnemonics and Recitation: Enhance memory retrieval.

Conclusion

• Understanding the complexities of memory, from processes to strategies for improvement, is essential for better cognitive function and adaptive behavior.