Memory Consolidation

Psychobiology of Cognition

H. Weingartner, E. S. Parker

• Publisher: Psychology Press
• Year: 2014
• eBook ISBN: 9781317769095
• Topic: Psychology
• Subtopic: Cognitive Psychology & Cognition
• Index: Psychology

First published in 1984. This volume was organized for students of human memory and related cognitive processes. The issues deal not only with memory in unimpaired individuals, but also with impaired patients and with consolidation in lower animals. The chapters in this volume demonstrate that consolidation is a flourishing and controversial concept in memory research today. More than ten years after the seminal book of M cGaugh and Herz, questions about consolidation are re-examined in light of current models of human memory, its pathology, and its modulation by drugs.

1	Memory Consolidation: A Cognitive Perspective

Herbert Weingartner
Laboratory of Psychology and Psychopathology
National Institute of Mental Health

Elizabeth S. Parker
Laboratory of Clinical Studies
National Institute on Alcohol Abuse and Alcoholism

AIMS

This volume is concerned with characteristics of memory consolidation. It addresses a historically classic concept that has been used to define aspects of learning, retention, memory, and related cognitive operations. The contributors to this volume explore a variety of issues that describe facets of memory consolidation. These include the biology, pathology, neuropsychology, neuropharmacology, and the behavioral events that are elements of the structure of such a construct. Questions are raised and discussed, such as: Is memory consolidation a useful metaphor? Under what circumstances? What types of biological and behavioral events are relevant in considering such a construct? What aspects of memory and memory phenomena require a memory consolidation explanation?

The volume has a second related agenda, namely to bring together historically disparate approaches to the study of learning and memory. Considerations of the biology, psychology, and pathology of human and lower animal learning and memory have progressed separately. This has seriously compromised what we might learn about complex memory-learning-cognitive phenomena. We believe that if we are to make substantial progress in understanding the psychobiological determinants of cognitive processes, then we must be prepared to integrate theory and data from these different areas of investigation. Without such a synthesis we will continue to ask weak questions and generate incomplete data. On the other hand, with an appropriate merging of those approaches, it should be possible to learn a great deal about the structure of cognitive processes.

We would hope that this volume will challenge current metaphors and concepts now used in memory research. The cognitive psychologist should obtain a picture of biological and clinical phenomena that are ordinarily outside his or her area of study but may in fact be relevant and important in defining aspects of memory and learning. Likewise, those interested in learning and memory in lower animals will find a discussion of memory consolidation based on the study of information processing in man equally worthwhile. Such a view of human memory may provide new insights about memory processes in lower animals. The volume may also be important for the neuroscientists who remain frustrated in relating brain events to behavior. If neuroscientists are going to help define the biological bases of higher mental processes, they must be as appreciative of the complexities and structure of cognitive behaviors as they are of biological tools and theories about the brain. Ultimately, it is of little value to map vague behaviors onto precise biological events.

POINT OF VIEW

Understanding the structure and determinants of how living systems adaptively respond to their environment, learn, and remember has persisted as a most important issue in psychology. Survival depends on effective appreciation and integration of information from the internal and external environment. To associate and respond to an event requires access to information about relevant prior experience, and the integration of the consequences of responses to ongoing stimulus events (information). Many psychologists have emphasized the importance of acquisition processes and, to a lesser extent, retrieval processes, in defining learning and memory; others have demonstrated the importance of postprocessing events in the establishment and maintenance of memory traces. In general, cognitive psychologists have shown relatively little interest in defining mediational-rehearsal processes that succeed initial acquisition of information. Other experimentalists have sustained their interest in the nature of postprocessing biological and behavioral events that may modify some central nervous system representation of previously processed experience. Scientists concerned with the biology of animal learning and memory have been most persistent in their interest in these postprocessing events. They, rather than investigators of human learning and memory, have found memory consolidation a useful working concept for considering how brain events might mediate memory processes. They have demonstrated that many types of treatments introduced after acquisition modulate and alter memory. The very fact that postprocessing events can affect what is “remembered” in lower animals is considered a reflection of the consolidation process at work. The period of time in which memory is susceptible to change may vary from milliseconds to hours, days, even years after training or learning. It would also appear that a number of different types of biological (and behavioral) systems may be involved in memory consolidation. Some of these systems are described by contributors to this book.

For those interested in human learning and memory, a memory consolidation construct has not been considered useful. Cognitivists have found other types of explanations and metaphors much more helpful in describing memory phenomena. These involve descriptors that can be more easily tied to observable behavioral events. Consolidation processes, as perhaps passive “unconscious” operations, are inconsistent with the behavioral operationalism of contemporary information-processing research. Nevertheless, the notion of memory consolidation merits reconsideration in light of recent advances in other areas of memory research. The contributors of the chapters that follow consider the value and structure of memory consolidation in a critical, evaluative, and integrative fashion.

BASES FOR CONSIDERING MEMORY
CONSOLIDATION

Despite the fact that memory consolidation refers to a subset of postprocessing events, it can mean a variety of things and imply varying processes to different investigators. It is not likely to be a single process or event.

Most of the data base for considering memory consolidation comes from psychobiological studies of lower animals with an emphasis on biological rather than behavioral events. Notions and theories about memory consolidation have also relied upon findings of the effects of various neuropharmacological agents introduced either before or after the acquisition of information in animals and more recently in humans. Other concepts of memory consolidation have also been based upon studies of impairments in memory and learning as seen in a variety of clinical syndromes. In contrast, cognitive psychologists have developed models and theories that have not included memory consolidation. For human memory researchers, postprocessing events have been considered in terms of cognitive operations and processes that would be expected to alter acquisition through changes in encoding. Furthermore, a consideration of postprocessing events, from a cognitive perspective, has not been logically or psychologically linked to consolidation processes in lower animals. Together, all of these research efforts have suggested a role for memory consolidation processes in particular and postprocessing events in general, in the development, maintenance, and retrieval of memories. A consideration of how memory consolidation might be useful in understanding cognitive phenomena may also provide a framework for bringing together the divergent approaches that have persisted in the study of memory and learning. As such, it may invite us to reformulate how we think about memory phenomena. These areas of study are reviewed by the contributors to this volume. We begin with a brief historical overview of learning and memory research because that may be helpful for understanding current differences in theory and approach to cognitive phenomena.

A HISTORICAL CONTEXT FOR CONSIDERING
MEMORY CONSOLIDATION

Any area of science can be seen as an evolution or unfolding of theory, metaphor, and models leading to experimental tests and new findings, which can then be used to support, modify, and sometimes refute our theoretical notions about a set of phenomena. This leads to new theories and descriptors for better defining our observations about a set of events. The metaphors, models, and theories we use determines the types of questions we ask, and what we consider important and worth explaining. This process by which our view of an area is altered is most frequently smooth, orderly, and continuous, with few dramatic shifts in theory and approach to problems. Part of the orderliness is artificially created by a consensually arrived at set of assumptions and accepted domain of theory that guides the behavior of a scientific community and determines how we ask questions, which questions are important, and which methods of research we employ. Theory also guides how we interpret findings. Occasionally there are dramatic changes in thinking about phenomena and the paradigms used to investigate them. Such upheaval is built upon new dramatic types of findings, rediscovery of important old findings, or fresh formulations of old theories and findings. Such paradigm shifts often produce changes in our thinking that go well beyond the areas of study that triggered these changes in viewpoint, method, and theory. There have been relatively few such sharp breaks in thinking about cognition, at least within experimental psychology. This is so despite the fact that we know little more about bases of learning and memory than we did 50 years ago. Perhaps this is because experimental psychologists, more so than physical scientists, focus more on how they do science than how they can solve the problems addressed. They are particularly vocal and explicit about what they consider psychologically and scientifically defensible approaches and what types of metaphors they find acceptable for describing and defining aspects of behavior. Perhaps we have been trapped in a historical rut and tradition which will be ineffective in solving how learning and memory work.

What is our historical heritage that determines how we examine learning and memory? All memory researchers have agreed on what questions need to be explored: What determines the acquisition (learning), retention, elaboration, and persistence of memory, and what influences the retrieval or performance of what has been learned? Many approaches to the study of these phenomena have evolved, and these have been pursued separately in human and animal learning.

At one time it was hoped that “laws” of learning and memory that were derived from the study of lower animals would be equally useful in accounting for human learning and memory. Lawful stimulus-response relationships were described in the form of mathematical statements based on notions of drive, motivation, the probabilities and strength of some response in a hierarchy of responses, or the relationship between stimuli. With behaviorism, general laws of learning and memory were stripped of concepts without clear behavioral referents such as many poorly understood intervening biological events (see Boring [1950] for an excellent treatment of this history).

For the past 30 years human learning and memory research has proceeded separately from the earlier tradition of a generalized approach to learning and memory. It has involved the study of acquisition and retreival processes but not of retention processes. That is, studies performed in the human learning laboratory have focused on the events that occur just before or at the time of information processing or at the time of the retrieval or performance of some learned behavior. The events that succeed information storage have been largely ignored, except by students of interference theories of memory. Within this research context cognitive psychologists have determined a great deal about the processes that mark the establishment of memory traces. Research has successfully defined some of the characteristics of stimuli that make them more or less noticeable, differentially encodable, easily learned, or learned with greater difficulty. Other research has characterized the capacity of our attentional memory system: still other studies have dealt with the ways in which organizational properties of stimuli can alter what is learned and what is remembered. We have learned something about how retrieval context in relation to encoding conditions determine whether a subject can successfully remember some information. These findings and related theory are discussed in all volumes on memory, learning, or information processing. Basic questions about what maintains information in memory are not asked by cognitive psychologists. A research void remains. Similarly, little is known, and there is little inquiry about, the plasticity of memory traces. Unlike animal learning and memory research, little work has been done relating postprocessing events that may take place immediately after learning with the ways these events alter what might be remembered at a later point in time. These postprocessing events would include biological as well as behavioral processes that occur during retention periods of various lengths.

When human learning and memory researchers shifted their efforts away from attempts to account for cognitive processes on the basis of theories of learning and memory in lower animals, they attempted to develop models of information processing that would isolate and define different components of acquisition. It was assumed that this could be done by studying unimpaired subjects in the human laboratory. They would provide the data base necessary to specify distinct stages of information processing that are part of the establishment of memories. Computer models and metaphors were first used to define how events are stored in memory. There was relatively little interest in what maintains memory traces. Little research was accomplished concerning the retrieval of information from memory. No effort was made to understand underlying biological processes. The research emphasis on acquisition processes for defining learning and memory continued with the recent development of single process theories of learning and memory. Although these levels of processing, or elaboration-encoding theories, were thought to provide a contrasting and perhaps competing framework for the analysis of memory, few new methods (or problems) were introduced to study memory phenomena.

All of the cognitive information-processing models that have been developed in the past three decades were designed to link the complex set of events that begin with receptor stimulation and end with some performance measure that would indicate memory or learning had taken place. A heritage of logical positivism and operationalism assured that the concepts, metaphors, and descriptors used to define aspects of information-processing models were limited to observable, verifiable behaviors that could be measured. One could manipulate the nature of stimuli and response conditions but not events inside a subject’s head. Unconscious, passive, subjective, mediational processes were therefore appropriately excluded as data and with it a concept such as memory consolidation was also omitted. Memory consolidation was difficult to operationalize, within the context of contemporary human memory research, and therefore could not be adequately studied in the human learning laboratory. In addition, most cognitive researchers were convinced that biological processes need not be a part of information-processing research—that memory and learning could be adequately studied in terms of behavioral events in the unimpaired subject. In fact, some contemporary cognitive psychologists such as Wickelgren, Landauer, and Bjork have used memory consolidation explanations (see Wickelgren, 1977, for a review). They are the exceptions, and this aspect of their research has had relatively little influence on other cognitive psychologists. Finally, the concept of memory consolidation was outside the domain of contemporary information-processing research, which was primarily concerned with how memories get formed or established during the brief period after stimulus exposure, at acquisition. Processes that extend well into the time in which subjects are attending to other stimuli were not of interest.

The study of impaired learning and memory has been of interest to yet another group of psychologists. Their training was often clinically focused and therefore different from those interested in the study of cognitive processes within the tradition of experimental psychology. The general focus of this clinical research was the cognitive dysfunction associated with some syndrome rather than laws that might govern memory processes. Nevertheless, these clinical research efforts, particularly those directed at describing memory pathology in neuropsychiatric populations, also resulted in the development of models, paradigms, and frameworks for defining aspects of memory. These models of disturbed memory relied more heavily on neurological metaphors and concepts and less on models of information processing based on the study of unimpaired subjects. Failures in recent memory, disruptions in accessing knowledge structures in semantic memory, and time-dependent retrograde amnesias were some of the phenomena of particular interest to these neuropsychologists. To the clinical neuropsychologist the notion of memory consolidation was considered particularly useful in accounting for retrograde amnestic effects. Descriptions of cognitive dysfunctions were detailed in patients with various kinds of relatively specifiable brain lesions that included structures such as unilateral or bilateral lesions of the temporal lobe, frontal lesions, limbic structures, etc., as well as studies of patients with reversible brain insults such as head trauma or those receiving electroconvulsive therapy. Single case studies of patients with rare and difficult to define lesions, the study of patients with temporal lobe dysfunctions, Korsakoff syndrome, progressive dementias, and localized head injury patients all served to provide an important clinical base for studying the pathologies of memory. There was relatively little integration of data or theory that emerged from the study of unimpaired individuals and the views of disordered human memory that grew from neuropsychological research. In general, the study of impairments in memory were either ignored by model builders investigating memory and learning in unimpaired subjects, or viewed with curiosity, sometimes interest, but no more so than other unusual or rare accidents of nature.

A behavioral tradition for the study of animal learning is well established. There is a well-established consensus about the key problems, questions, and concepts that remain unresolved in accounting for learning and performance in lower animals. What are the elements, conditions, structure, topography of learning a set of stimulus-response relationships? Observable behavior is the basis of such theorizing; hypothetical constructs are unacceptable. In addition, it is internally consistent to argue that the same lawful relationships that define animal learning should serve to account for how man learns and remembers. Findings from the study of human information processing, learning, and memory, and its pathology have not been considered particularly useful for those interested in how animals learn and remember (perform some behavior). The study of the biology of animal learning and memory has also been largely ignored by most behaviorists interested in laws of learning and memory.

The study of the biology of learning and memory has also developed separately from the study of the psychology of learning and memory. Although research efforts have provided an increasingly detailed picture of brain events that may be relevant for learning and memory, they have been mapped onto vague and poorly defined behavioral measures. This has been the case precisely because studies of biological determinants of memory have been pursued in relative isolation from the study of human learning, behavioral studies of animal learning, and cognitive pathologies. The neuroscientist has considered “going it alone” as his tools have become increas...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• 1. Memory Consolidation: A Cognitive Perspective
• 2. Cognitive-Affective Integration: Some Recent Trends From a Neurobiological Perspective
• 3. Endogenous Processes in Memory Consolidation
• 4. The Physiology and Semantics of Consolidation
• 5. Consolidation as a Function of Retrieval
• 6. Consolidation and Forgetting Theory
• 7. Departures from Reality in Human Perception and Memory
• 8. The Medial Temporal Region and Memory Consolidation: A New Hypothesis
• 9. Implications of Different Patterns of Remote Memory Loss for the Concept of Consolidation
• 10. Retrograde Facilitation of Human Memory by Drugs
• Author Index
• Subject Index