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Bermúdez-Rattoni F, editor. Neural Plasticity and Memory: From Genes to Brain Imaging. Boca Raton (FL): CRC Press/Taylor & Francis; 2007.

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Neural Plasticity and Memory: From Genes to Brain Imaging.

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Preface

The major goal of this book is to create a comprehensive multidisciplinary review and in-depth, up-to-date analysis of the study of the neurobiology of memory. The world’s leading specialists share some of their scientific experience in the field, covering a wide range of topics relating how molecular, genetic, behavioral, and brain imaging techniques have been used to investigate the ways by which cellular and brain circuits may be modified by experience.

The opening chapter by James L. McGaugh, one of the leading researchers in the field of memory consolidation and brain plasticity, offers an interesting introduction to the main issues. McGaugh gives us a historical overview of the field of memory consolidation, formally initiated 100 years ago, and its enormous expansion during the last three decades. His chapter emphasizes the methodological and conceptual problems inherent to the study at different levels of analysis, from the cellular mechanisms to the systems interactions for the representation of long-lasting memories.

Subsequent chapters contain interesting reviews of the putative genetic and molecular mechanisms of cell plasticity. Several authors elaborate on how experience may induce gene and protein expression and describe the role of experience in synaptic plasticity underlying memory formation. Specifically, the authors reveal how cell circuitry is modified and modulated by electrical activity or exposure to novel spatial environments. Martha L. Escobar and Brian Derrick review work on the synaptic communication elements described as susceptible to be modified by activity and experience. In particular, they give us a journey through up-to-date studies on one of the more exciting and heuristic models of brain plasticity, long-term potentiation (LTP) and its reverse counterpart, long-term depression (LTD). In addition, they put forward important questions regarding the hypothesis that these models may be related to brain plasticity underlying memory formation. Similarly, Victor Ramirez-Amaya summarizes recent research examining gene and protein expression in brain circuits. With up-to-date techniques, he proposes the steps by which a particular ensemble of neurons becomes interconnected with others after spatial experience and how these interconnected ensembles may stand for spatial memory representations in the hippocampus.

In the following chapters, several investigators address the question of how putative modifications of brain circuits and synaptic elements through experience can become relatively permanent and hence improve brain function. A major discovery made in recent decades was the seminal finding regarding brain modification after experience by Mark R. Rosenzweig. His chapter relates a historical approach to functional, biochemical, and structural transformations in some brain areas after exposure to enriched environments during animal development. Similarly, the chapter by Jerome L. Rekart, Matthew R. Holahan, and Aryeh Routtenberg reviews how brain modifications occur in both developing animals and in adult animals in relatively short periods after spatial learning. In particular, they explore how axonal sprouting and dendrite spine modification of adult animals are induced in certain areas of the hippocampus during spatial memory formation.

The following section includes interdisciplinary reviews focusing on how nerve cell circuitry, molecular expression, neurotransmitter release, and electrical activity are modified during the acquisition and consolidation of long-term memory. In “Electrophysiological Representation of Taste Memory,” Takashi Yamamoto and Yasunobu Yasoshima examine ongoing research on cellular changes in specific brain areas induced by experience. In particular, they use a model known as conditioned taste aversion — one of the most useful and effective methods for enabling animals to remember tastes. They review electrical changes in several brain areas after taste-illness experiences; specifically, they analyze how cortical and amygdalar cells change their responses to tastes after aversive experiences. In the same area, Maria Isabel Miranda reviews the literature related to the release of several neurotransmitters as measured with state-of-the-art methodologies such as in vivo microdialysis during different stages of memory formation, i.e., acquisition, consolidation, and retrieval. Her chapter explains how differential releases of various neurotransmitters and molecules help us to better understand and eventually modify memory formation and retrieval.

Subsequent chapters deal with receptor activation and deactivation via different neurotransmitters that enable the intracellular activation of second messengers during memory formation. The chapters by Milagros Gallo and Roberto A. Prado-Alcalá and co-workers deal with brain inactivation at different stages of memory formation. In particular, Gallo tracks down the development of methodologies to analyze brain functions and memory formation such as reversible pharmacological inactivation, protein synthesis blockers, and genetic inactivation techniques. Prado-Alcalá and co-workers describe pharmacological approaches for the better understanding of the underlying mechanisms of aversively motivated memory formation and introduce the hypothesis that it is possible to protect the brain against the effects of amnesic drugs by enhancing learning experiences.

Interestingly, Iván Izquierdo and co-workers challenge the hypothesis that short-term and long-term memories are serial events leading to memory consolidation as previously proposed. Instead they suggest that short- and long-term memories are parallel events. This proposal is based on recent findings in which intracerebral administration of different agonists and antagonists of several neurotransmitters produce disruptive effects on short- but not on long-term memory in the same animals. In addition, they support this hypothesis with data showing differential susceptibilities of LTM and STM to extinction and novel experiences.

The chapter by Rodriguez-Ortiz and Bermúdez-Rattoni summarizes recent research examining the new and hot topic of post-retrieval memory consolidation, the so-called reconsolidation process. The reconsolidation hypothesis suggests that consolidated memory returns to a labile state similar to recently acquired memory each time it is retrieved and is susceptible to disruption by the same treatments or drugs that disrupt memory consolidation. Their chapter reviews and challenges the reconsolidation hypothesis by proposing that retrieved memory can be modified as part of a mechanism for incorporating updated information into previously consolidated long-term memory.

Chapters in the last section of the book summarize current research on the modulation and regulation of the formation and consolidation of memory by different neurotransmitters and stress hormones. In her chapter, Carmen Sandi proposes that the memory dysfunctions observed after stress and aging may be related. She provides interesting evidence that some of the neural mechanisms of memory disability from stress are similar to the neural mechanisms found in memory impairments from aging. The chapter by Christa K. McIntyre and Benno Roozendaal analyzes current research on the effects that systemic and central stress hormones have on the formation and consolidation of lingering memories and their possible therapeutic use for post-traumatic stress syndrome in humans.

At the end of this section, human research on memory formation is analyzed under the framework of immune system responses and brain communication; the methods by which brain sexual differences during emotional memory formation are studied via brain imaging techniques are also discussed.

For some time it has been known that stress and/or depression induce immune response deficits to diverse immunological challenges. In this regard, Gustavo Pacheco-López and Manfred Schedlowski unveil interesting aspects of the so-called neuro-immune associative learning. Their chapter reviews a number of experiments showing how animals and humans are able to associate immune responses with specific stimulus (environments, tastes) and modify their immune responses for longer periods.

A number of studies ranging from laboratory animals to humans indicate that endogenous stress hormones and the amygdala interact to modulate memory consolidation for emotional events. Within this framework, Larry Cahill explores brain activity modifications during memory formation with the use of newly and highly sophisticated methods of brain imaging in humans, namely positron emission tomography (PET) and functional magnetic resonance (FMR). In his chapter, he analyzes several lines of investigation leading to the conclusion that males and females do not process emotional memories in the same way in particular brain areas like the amygdala. He clarifies that sexual differences are very important and should be taken into account when exploring the neurobiology of emotional memory formation and eventually improve treatments for related clinical disorders.

I would like to thank Dr. James McGaugh and Dr. Roberto A. Prado-Alcalá for their valuable comments and ideas and Israela Balderas, Vanesa Cruz, and B.A. Yahan for reviewing certain chapters. I also want to thank Dr. Sid Simon and Dr. Miguel Nicolelis, editors of the Frontiers in Neuroscience series and Barbara E. Norwitz and Jill Jurgensen of Taylor & Francis Group for their support.

Copyright © 2007, Taylor & Francis Group, LLC.
Bookshelf ID: NBK3918

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