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Objectives
After studying this chapter, the student should be able to:
Define the 3 components of memory: encoding, storage, and retrieval.
Distinguish and describe the temporal phases of memory: sensory, short-term/working, and long-term memory.
Diagram the working memory model and its components, and identify the underlying brain mechanism of short-term working memory.
Define the 2 information processing systems—declarative/explicit and nondeclarative/implicit memory—and describe their subsystems.
Identify the brain regions involved in the information processing subsystems.
Explain synaptic and systems consolidation and the role of sleep in memory consolidation.
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OVERVIEW OF MEMORY & MEMORY SYSTEMS
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One of the essential cognitive functions, memory involves the mental processes by which information is encoded, stored, and retrieved. Memory is thought to involve physical changes in the brain, called engrams or memory traces. In cognitive neuroscience, memory is defined not only by encoding and storing of the engram, but also through expression, which refers to the retrieval of stored information that leads to modification of behavior or conscious thought. Memory allows us to accomplish everyday physical and living activities and is critical for other key cognitive processes including language, planning, reasoning, and problem solving; it is also a fundamental component of our personality and consciousness.
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Memory is the basis for the amassment of knowledge, the importance of which is exemplified by Francis Bacon’s quote “Knowledge itself is power.” Diminished learning and memory occur in normal aging and are common features of intellectual disability, traumatic brain injury, schizophrenia, Parkinson disease, and Alzheimer disease. Based on its central role in human behavior and disruption in many brain disorders, memory has been studied extensively in the fields of psychology, neuroscience, and clinical medicine. In this chapter, the various memory systems will be elaborated. Complementing this chapter is Chapter 10, “Synaptic Plasticity,” in which synaptic plasticity mechanisms implicated in encoding of memory are described.
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In the broadest sense, memory can be categorized into collective memory and individual memory. Collective memory is a shared pool of knowledge by members of a social group, usually requiring symbolic representation such as language, and often studied in the discipline of sociology. The modern concept of human individual memory (hereafter memory) involves characteristic features. First, memory encompasses at least 4 components: acquisition, consolidation, storage, and retrieval, also called recall. Consolidation involves processes that stabilize a memory trace after its initial acquisition; learning consists of acquisition and consolidation and is also called encoding. Learning is a graded phenomenon, and most forms of memory can be either short lasting or long lasting. Second, memory involves multiple memory systems that depend on the specific type of information processed. Consequently, memory can be classified according to 2 features: the time course of learning and storage and the nature of the information learned and stored.
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Focusing first on the time course, human memory involves informational processing systems with distinct temporal components. The idea ...