S. R. Eshraghi 2008-10-21
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LeDoux provides a fascinating take on the big question facing researchers of the brain: "What makes us who we are?" He postulates that all functions of an individual can be explained by the synapses through which they are executed.
I was attracted to Synaptic Self because throughout my undergraduate studies I have focused on neuroscience, psychology, and the interaction between the two fields. I found the main idea to be a magnificent extension from the recent findings of neuroscience research, but once I finished the book, I was left with the feeling that the conclusion wasn't complete--more is to be said on the topic of the self. I also feel that LeDoux could have avoided the excessive name-dropping by giving more straightforward examples because, at times, the dense experimental evidence took away from the point he was trying to make.
A general reader may find many parts of this book challenging to understand due to the intricacies of the subject matter. Contrarily, I believe LeDoux has attempted to make this book as accessible as it can be by using the following techniques: (1) he uses simple line drawings to illustrate complex ideas; (2) he gives numerous examples from past and present research to support the major points made; and (3) he structures the book and writes with a style much like an informative textbook to get his ideas across to the general consumer.
Joseph LeDoux's experimental work examines the underpinnings of emotion and memory in the brain, focusing efforts on the amygdala and the hippocampus. His lab uses classical fear conditioning in order to study how traumatic memories are formed, stored, and retrieved. Since LeDoux's previous book, The Emotional Brain, obviously deals with emotion, Synaptic Self focuses on what is left: memory.
The overall purpose of the book is stated the following way: "[I]n order to understand the self, we need to explain how brain systems underlying thinking, emotion, and motivation (the mental trilogy) develop under the influence of nature and nurture, and how these systems make it possible for us to attend to, perceive, learn about, and store and retrieve experiences" (p. 32). LeDoux breaks this goal down into several smaller portions that build upon each other: (1) basic "machinery" of the brain; (2) development of the brain and synapses; (3) two kinds of memory--explicit and implicit--and how they are formed (LTP); (5) integration of the mental trilogy--cognition, emotion, and motivation; (6) result of a disconnect in the mental trilogy; and, to put it all together, (7) seven principles of how synapses create the self
Basic "Machinery" of the Brain (Ch. 3)
In order to set the stage for his main topic, LeDoux gives a brief and informative introduction to the mechanisms of the brain. He begins with a history of neuroscience that leads into a discussion of the structure of neurons, the conduction of action potentials, and, finally, transmission at synapses. He ends the chapter with this statement: "While synapses themselves don't account for everything the brain does, they do participate crucially in every act or thought that we have, and in every emotion we express and experience. Synapses are ultimately the key to the brain's many functions, and thus to the self" (p. 64). I believe that this statement sums up the entire book.
Development of the Brain (Ch. 4)
LeDoux examines the development of synapses through two very different theories: selectionist nativism and instructional constructionism. The former theory states that synapses are pruned, in a sense, by experiences. The latter theory postulates that new synapses are built. He concludes that the brain develops through both of these mechanisms.
Two Types of Memory (Ch. 5 and 6)
Through an in depth analysis of implicit (nondeclarative) and explicit (declarative) memories and how they are created, LeDoux comes to this conclusion: "The essence of who you are is stored as synaptic interactions in and between the various systems of your brain. As we learn more about the synaptic mechanisms of memory, we learn more about the neural basis of the self" (p. 173).
The Mental Trilogy (Ch. 7, 8, and 9)
These chapters stretched on for me as they examined cognitive, emotional, and motivational functions of the brain, respectively. His main point from these chapters is that mental life involves complex interactions between many systems and circuits in the brain.
Perversion of the Mental Trilogy (Ch. 10)
Here, LeDoux takes the chance to examine a few diseases of the brain and how the treatments for them are engineered to act at the synaptic level. The diseases he examines are schizophrenia, depression, and anxiety disorders. He concludes that these diseases are caused by a disjunction between or within a component of the mental trilogy. I felt that this chapter was out of place
Seven Principles (Ch. 11)
In the final chapter, LeDoux proposes seven principles to explain "how synaptic plasticity in multiple neural systems is coordinated in the process of assembling, and maintaining, the self" (p. 307). Basically, he states that the simultaneous divergence and convergence of information from several systems in the brain creates our memories, and those memories make us who we are. His attempt in this chapter is bold and almost complete, but it left me wanting to read a more in depth explanation.
Overall, I would recommend Synaptic Self to all readers interested in a valid, fascinating, and scientific explanation of individuality. Looking back, I think that it is appropriate for the book to leave you with a sense of incompleteness because it is impossible with the current methods of science to discover absolutely everything about the brain.
