Learning and Memory

Learning & Memory Study Guide

Learning

Nonassociative vs. Associative Learning

• Nonassociative Learning: Learning about a single stimulus.

  • Habituation: Decreased response to repeated stimuli (e.g., tuning out background noise).

  • Sensitization: Increased response to repeated stimuli (e.g., heightened reaction to a loud noise after a scare).

• Associative Learning: Learning a connection between stimuli or behaviors.

  • Classical Conditioning (Pavlovian): Associating two stimuli (e.g., dog salivates to bell after repeated pairings with food).

  • Operant Conditioning: Associating behavior with consequences (e.g., studying more to get good grades).

Explaining Learning in Scientific Terms

• Acquisition: Initial learning phase where associations are formed.

• Extinction: The weakening of a learned response when reinforcement or stimulus pairing stops.

• Generalization: Responding similarly to similar stimuli (e.g., Little Albert feared all furry objects, not just white rats).

• Discrimination: Learning to differentiate between stimuli (e.g., responding to a specific tone but not others).

Key Features of Reinforcement Learning Models

• Prediction Error: Learning occurs when there’s a mismatch between expected and actual outcomes.

• Temporal Difference Learning: Future rewards influence present behavior.

• Rescorla-Wagner Model: Learning depends on the difference between expected and actual reinforcement.

Dopamine’s Role in Learning

1. Before Learning: Dopamine spikes in response to unexpected rewards.

2. During Learning: Dopamine shifts to the cue that predicts the reward.

3. After Learning: If reward is omitted, dopamine levels drop → signals prediction error.

Major Dopamine Pathways

• Mesolimbic Pathway (Reward & Motivation): Ventral tegmental area (VTA) → Nucleus Accumbens.

• Mesocortical Pathway (Cognition & Decision-Making): VTA → Prefrontal Cortex.

• Nigrostriatal Pathway (Movement): Substantia Nigra → Striatum (affected in Parkinson’s).

• Tuberoinfundibular Pathway (Hormone Regulation): Hypothalamus → Pituitary Gland.

Debunking the Myth: "Dopamine = Feel-Good Chemical"

• Dopamine doesn’t directly cause pleasure; it signals motivation, prediction error, and learning.

• Studies show that blocking dopamine doesn’t eliminate pleasure but reduces motivation to seek rewards.

• Example: Parkinson’s patients have low dopamine but still experience pleasure from music or food.

Applying Learning Principles to Real-World Issues (e.g., Addiction)

• Operant Conditioning: Drug use reinforced by pleasurable effects.

• Classical Conditioning: Environmental cues trigger cravings.

• Dopamine & Reinforcement Learning: Drugs hijack the reward system, creating excessive prediction errors.

• Application: Behavioral therapies (e.g., cue exposure therapy) aim to break conditioned responses.

Memory

Short- & Long-Term Memory Types

• Short-Term Memory (STM): Temporary storage (~30 seconds), limited capacity (~7±2 items).

• Working Memory: Active processing (e.g., mental math, following directions).

• Long-Term Memory (LTM): Lasts for days to years, unlimited capacity.

Types of Long-Term Memory:

1. Explicit (Declarative) Memory: Conscious recall.

   • Episodic Memory: Personal experiences (e.g., birthday parties).

   • Semantic Memory: General knowledge (e.g., capital of France is Paris).

2. Implicit (Nondeclarative) Memory: Unconscious skills and habits.

   • Procedural Memory: Motor skills (e.g., riding a bike).

   • Priming & Conditioning: Learned associations (e.g., hearing a song and recalling a memory).

Stages of Memory Formation

1. Encoding: Converting information into neural signals.

2. Storage: Consolidating information into long-term memory.

3. Retrieval: Accessing stored memories.

Evidence for Multiple Memory Systems

• HM (Henry Molaison): Lost episodic memory after hippocampus removal but retained procedural memory (e.g., improved at mirror tracing).

• Clive Wearing: Severe amnesia; could play piano (procedural memory intact) but had no episodic recall.

• Double Dissociation: Patients with hippocampal damage lose explicit memory but retain procedural skills, supporting separate systems.

Predicting Amnesic Patient Performance on Memory Tasks

Taxonomy of Long-Term Memory

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Long-Term Memory ├── Explicit (Declarative) Memory │ ├── Episodic Memory (Personal Events) │ ├── Semantic Memory (Facts, Knowledge) │ ├── Implicit (Nondeclarative) Memory │ ├── Procedural Memory (Skills, Habits) │ ├── Priming & Conditioning (Learned Associations)

Memory Formation at Neural & Network Levels

• Individual Neurons: Long-Term Potentiation (LTP) strengthens synaptic connections, crucial for learning.

• Neural Networks: Hippocampus consolidates memories; cortical areas store long-term knowledge.

Key Brain Structures in Memory

• Hippocampus: Crucial for encoding new explicit memories.

• Amygdala: Emotional memory processing.

• Prefrontal Cortex: Working memory & decision-making.

• Basal Ganglia & Cerebellum: Implicit memory & motor learning.l

• Thalamus: Relay station for sensory and motor signals, playing a role in attention and memory formation.

• Mammilary bodies: essential for episodic memory formation and are part of a broader network linking the hippocampus, thalamus, and cortex. Damage to these structures impairs memory recall and learning