The Synaptic Self: A Book Commentary
Joseph LeDoux is a man who wears many hats. Neuroscientist. Professor. Researcher. Historian. Critic. As the author of Synaptic Self: How Our Brains Become Who We Are, he integrates these roles in attempt to solve one of what he calls neuroscience's key overarching problems, the origin of the self. His thesis, that your self, the essence of who you are, is simply patterns of interconnectivity between neurons is given early in the first chapter. Realizing that "many will surely counter that the self is psychological, social, moral, aesthetic, or spiritual, rather than neural, in nature" (LeDoux 3), LeDoux delves into the history of neuroscience to assemble a strong argument for a neural account of the self. Along the way, he concentrates his efforts on three faculties, cognition, emotion, and motivation, that form embody the self he seeks to define. By describing the self as a system of interconnected synapses that constantly influence and interact with each other, he answers one of neuroscience's trickiest questions: What makes us who we are?
LeDoux begins by explaining how synaptic organization can lead to an infinite number of personalities. As animal breeders know, there is a known genetic component to several personality traits, such as extroversion, aggression, and fearfulness, and for the probability of developing a mental illness like depression, anxiety, or schizophrenia. For LeDoux, it follows that if a personality trait is heritable, then these genetic forces are acting on the arrangement of neurons in the brain, because synapses are the basis for all of the brain's actions. Genes that operate on neurons and synapses play a role in constraining the way we think, act, and feel. Experiences are inherently synaptic and influence personality by the same mechanism, the organization of neurons in the brain, as genes. Learning and memory, results of experience, alter the arrangement of synapses.
LeDoux views the mind as a trilogy. Cognition, emotion, and motivation are independent faculties of the mind that interact with and influence each other. In order to assemble a neurological view of the self, LeDoux examines each component of the mind separately and the interactions among them. The mind is constantly juggling and changing fragments of its mental states using working memory. "Working memory is one of the brain's most sophisticated capacities [ . . . ] involved in all aspects of thinking and problem-solving" (175). Emotion, the process by which the brain determines the value of a stimulus, also plays a role in the assembly of the self. LeDoux differentiates this process from cognition by suggesting that during an emotional response, the brain is unconsciously stimulated. A feeling, then, is the working memory's representation of the various elements of the emotional state it is currently in. Finally, motivation is the neural activity that guides us toward an incentive. Cognition, emotion, and emotion interact to produce the integrated system we call the mind.
The components of working memory are located in different areas of the prefrontal cortex that work together to integrate information and interact with the rest of the brain. Consciousness, LeDoux claims, can be thought of as the product of underlying cognitive processes, and the things that we are conscious of are the things that our working memory is working on. Cognitive processing can be accompanied by an emotional response; likewise, an emotional arousal may guide us toward an incentive or we may make a cognitive decision about how to further a goal or resolve a motivational conflict.
Some of the similarities between LeDoux's synaptic self and our Neurobiology and Behavior model are quite obvious. When we discussed the organization of the nervous system, we talked about behavior as the arrangement of neurons; personality is just another word for "behavior." And Although LeDoux's exploration of behavior follows a different path, the synaptic model of the self - specifically working memory - easily lends itself to comparison with our model of the I-function. Emotion and motivation, as I understand them, are specific boxes in the nervous system that we're not conscious of. The I-function is a box in the brain that influences and is influenced by other boxes in the brain. In our model, the I-function fulfills the role of the story teller, mediating its interactions with the rest of the nervous system by composing stories with language. LeDoux's working memory is clearly a box in the brain that is constantly interacting with other boxes in the brain. It is also where LeDoux places language. Humans are separate from all other organisms in that we have both verbal and nonverbal working memory. Verbal working memory allows us to "represent complex, abstract concepts (like "me" or "mine" or "ours"), to relate external events to these abstractions, and to use these representations to guide decision-making and control behavior" (197), just as the I-function creates the "self" as an object as part of its interplay with the rest of the nervous system.
In the concluding chapter, LeDoux considers how it is even possible for a person to have a stable personality, the unconscious aspects of the nervous system working in tandem. We try to willfully dictate our behavior using executive functions that arise out of cognition. It's an imperfect system, as we are unable to completely control our emotional system, but remarkably, most of the time, the brain holds itself together pretty well. The synaptic self gives an account for personality that incorporates, through the idea of working memory and the trilogy of systems, the experience we personally have as ourselves as objects as well as illustrates the principles behind changes in behavior. Personally, I found some of LeDoux's predictions about the future of neuroscience hopeful and exciting. He issues a challenge the field to use this new understanding of personality to better treat mental illness. "An important challenge for the field of neuroscience is to figure out how to manipulate the brain in a way that patients with mental disorders can, either alone or with the help of a therapist, try to put the self's synapses back together" (307). As LeDoux's influence in the field grows, I am hopeful that a synaptic view of the self may lead to many exciting developments in neuroscience.