65: Learning and Memory

Introduction

• Short-Term and Long-Term Memory Involve Different Neural Systems

  • Short-Term Memory Maintains Transient Representations of Information Relevant to Immediate Goals

  • Short-Term Memory Is Selectively Transferred to Long-Term Memory

• Long-Term Memory Can Be Classified As Explicit or Implicit

• Explicit Memory Has Episodic and Semantic Forms

  • Explicit Memory Processing Involves at Least Four Distinct Operations

  • Episodic Knowledge Depends on Interaction Between the Medial Temporal Lobe and Association Cortices

  • Semantic Knowledge Is Stored in Distinct Association Cortices and Retrieval Depends on the Prefrontal Cortex

• Implicit Memory Supports Perceptual Priming

  • Implicit Memory Can Be Associative or Nonassociative

  • Classical Conditioning Involves Associating Two Stimuli

  • Operant Conditioning Involves Associating a Specific Behavior with a Reinforcing Event

  • Associative Learning Is Constrained by the Biology of the Organism

• Errors and Imperfections in Memory Shed Light on Normal Memory Processes

• An Overall View

In his masterful novel One Hundred Years of Solitude Gabriel Garcia Marquez describes a strange plague that invades a tiny village and robs people of their memories. The villagers first lose personal recollections, then the names and functions of common objects. To combat the plague, one man places written labels on every object in his home. But he soon realizes the futility of this strategy, because the plague eventually destroys even his knowledge of words and letters.

This fictional incident reminds us of how important learning and memory are in everyday life. Learning refers to a change in behavior that results from acquiring knowledge about the world, and memory is the process by which that knowledge is encoded, stored, and later retrieved. Marquez's story challenges us to imagine life without the ability to learn and remember. We would forget people and places we once knew, and no longer be able to use and understand language or execute motor skills we had once learned; we would not recall the happiest or saddest moments of our lives, and would even lose our sense of personal identity. Learning and memory are essential to the full functioning and independent survival of people and animals.

In 1861 Pierre Paul Broca discovered that damage to the posterior portion of the left frontal lobe (Broca's area) produces a specific deficit in language. Soon thereafter it became clear that other mental functions, such as perception and voluntary movement, are also mediated by discrete parts of the brain (see Chapter 1). This naturally led to the question: Are there discrete neural systems concerned with memory? If so, is there a "memory center" or is memory processing widely distributed throughout the brain?

Contrary to the prevalent view that cognitive functions are localized in the brain, many students of learning doubted that memory is localized. In fact, until the middle of the 20th century many psychologists doubted that memory is a discrete function, independent of perception, language, or movement. One reason for the persistent doubt is that memory storage involves many different parts of the ...