What is memory, and where and how is it stored in the brain? Throughout human history, people have struggled to answer these questions, and up until the last century or so, they seemed like questions best left to philosophers. However, within the last century we have developed a better understanding of the systems of the brain and their cognitive functions. Even more importantly, we now know many of the basic cellular and molecular principles by which the brain operates. The goal of this book is to bridge these two systems of understanding and, in so doing, to create a new model of understanding, one which emphasizes the relatedness between the molecular basis of memory and the cognitive aspects of memory.

In attempting to accomplish this goal, this book brings together two of the foremost experts in the field of memory: Eric Kandel, who has made important contributions to understanding the physiological basis for memory, and Larry R. Squire, an expert on brain systems and the cognitive aspects of memory. The first and last chapters of this book were coauthored by these two men, while in the intervening chapters the two authors take turns presenting their views. It seems like their goal in writing these chapters was not to provide an exhaustive treatment of the subject of memory but to present a panoramic view from the perspective of their own research and understanding. This is evident in the numerous references to the experiments carried out in their labs or in collaboration with others.

Synopsis

Kandel begins his treatment of this subject by explaining how brain cells, or neurons, communicate with one another. This is accomplished by the transmission of chemical signals, or neurotransmitters, from one neuron to another across synapses. A century ago, the brilliant neuroanatomist Ramon y Cajal postulated that the brain forms memories by modifying these synapses, whether by increasing the amounts of neurotransmitters that are released or by growing new synaptic processes. Kandel confirmed this hypothesis using the gill-withdrawal reflex of Aplysia californica (aka. the sea snail), which exhibits a very elementary kind of memory called nondeclarative memory. Kandel demonstrated that Aplysia can unconsciously "remember" the difference between a harmless stimulus and a harmful one, as evidenced by the habituation or sensitization of the gill-withdrawal reflex, and that this kind of remembering is reflected in changes in the synapses involved in generating the reflex. Thus, Kandel established the principle of "synaptic plasticity" and also helped confirm the idea that memories are not localized in a certain part of the brain but are rather "encoded" into the very neural circuits that cause a behavior or reflex. In his discussion, he also reveals that the synapse is quite a complex connection involving the convergence of several second-messenger systems, which modulate the amounts of neurotransmitters released.

In the following chapters, Squire turns to a more complex form of memory--declarative memory, which, unlike nondeclarative memory, is accessed consciously, as when trying to recall an event. He begins by describing the encoding, storage, and retrieval of declarative memory from a cognitive perspective. He also reveals that declarative memory is often imperfect and can be forgotten over time. Although most of us would view this as a liability, Squire reasons that such imperfections are normal and even necessary, for they allow us to filter out distracting details and extract important concepts from our experiences. Declarative memory begins as "short-term memory," which is limited in its capacity and can be lost. Over time, however, that "short-term memory" can be converted to "long-term memory" through a process that involves the medial temporal lobe of the brain, particularly the hippocampus. Squire describes what is currently known about this process and the role of the hippocampus in organizing and stabilizing neuronal connections, particularly through the observation of patients with amnesia, who often exhibit hippocampal damage.

Kandel continues the discussion by examining the molecular basis for storage of declarative memory and for the conversion of short-term memory to long-term memory. The storage of declarative memory occurs via a family of processes that occur in the hippocampus called long-term potentiation (or LTP). LTP involves various presynaptic and postsynaptic second-messenger systems, similar to the ones that modulate the release of neurotransmitters in the gill-withdrawal reflex of Aplysia. Research has shown that LTP in the hippocampus plays an important role in an organism's ability to form spatial maps of its environment. Kandel also explains the genetic basis behind the conversion of short-term memory to long-term memory. The theory behind this conversion is that neurotransmitters set off a second-messenger cascade that activates the transcription of certain genes, which ultimately leads to permanent anatomical changes in synapses, such as growth of new synaptic processes. It is striking to see how the storage mechanisms for short-term memory and long-term memory use the same molecules in slightly different ways to produce synaptic changes that vary in permanence.

Squire then returns to nondeclarative memory to examine how the brain unconsciously acquires and processes information from our environment. His discussion of this topic is framed around various phenomena such as priming, perceptual learning, emotional learning, skill learning, habit learning, and conditioning, all of which illustrate how nondeclarative memory operates in conjunction with and enhances declarative memory. These kinds of nondeclarative learning are presented mainly from a systems-based view, but occasionally, Squire links these phenomena to the molecular understanding of synaptic modulation established in previous chapters. In the last chapter, the authors examine the role of synaptic modulation in the learning and development of the brain, as well as in the degeneration of the brain through age-related memory loss and Alzeheimer's disease.

Recommendation

Overall, I really enjoyed reading this book. On the one hand, it covers many foundational concepts regarding the neuroscience of the brain, acting as a primer for anyone interested in this subject. On the other hand, it builds upon this foundation to explore some of the current lines of research and to present a unique view of cognition from the molecular perspective, linking these two important systems of understanding in a novel way. That said, I would not recommend this book to the "non-scientific" reader or to someone looking for a light read. This book is very dense and requires focus and concentration while reading. It would be most useful to undergraduate and graduate students who have a solid foundation in cellular biology and an interest in neurobiology. For these students, many of the foundational concepts in this book will be immediately familiar, and the authors do a good job of extending those concepts to elucidate new concepts in an understandable way.

A good chunk of the book is basically an historical account of various experiments that Kandel, Squire, and others performed. In presenting these experiments, the authors step through the entire experimental process, beginning with a specific question, then describing the design and carrying out of the experiment, and finally presenting and interpreting the results. This might seem a bit tiresome to those who merely want to know the conclusions of their research, but I found the accounts very instructional and insightful in revealing the way these scientists think. The logic inherent in their thought processes is evidenced by the way they proceed from one question and experiment to the next, constantly using what they know to ask new questions and to probe the unknown. The volume of meaningful research they have accomplished is astounding. The book also provides many excellent illustrations that help in understanding the experimental procedures and results.

A previous reviewer on Amazon critiqued the authors for assuming that memory is encoded through synaptic changes and not through some other mechanism. I agree that there may be more to memory than synaptic changes and that perhaps in 5 or 10 years, as our understanding of memory grows, much of this book may seem elementary or even proven wrong. Nevertheless, until that paradigm shift occurs, I think this book presents a succinct and thorough overview of how memory works based on our current understanding. Like memory itself, the study of memory seems to be a constantly changing landscape in which new concepts arise and old ones are either overturned or entrenched in our understanding. However, this book provides a solid footing on which we can further our understanding of memory and the mind and link that understanding to the broader study of human experience.

One of my favorite neuroscience books.. The art at the beginning of the chapter always relates to the chapter itself. It explains topics in the simplest of terms.

I loved reading about the experiments and learning the mechanisms in which synapses are strengthened. This book is one of the biggest reasons I am interested in learning and memory. When I opened this book I found a lot more than I thought was involved and it was amazing. There is grey area but that's mostly due to this field. Not much is truly known in this area. But this book explains what is known.

Great book, well written and beautiful to boot. I may write a more in depth review later.

I hope a new edition comes out, as this is slightly dated. However, it is comprehensive, clear, and engaging.

This is a very high quality production. The illustrations alone are a thing of beauty. Fascinating subject written by one of the true pioneers of modern neurology and memory. Wonderful book.

written in prose form, fantastic text book. love the incorporation of art pieces. ties memory together from all aspects, wonderful approach. highly recommended for students and professors in neuroscience. .

The best book I have ever read!

Larry Squire is a genius.