Afterword

Early in his career, Freud turned away from the brain because he felt the tools available were inadequate for addressing the complexities of the human mind. The field of psychoanalysis was the result. Early in his career, Eric Kandel, after receiving his psychoanalytic training, embraced the brain because he felt neuroscience was ready to tackle the mind. Memory, so important to Freud, was his target. Kandel's aim was high, but he started low, working on memory in an invertebrate. His critics said this was learning, but it had nothing to do with memory in the sense of human memory. Slowly, over the decades, Kandel pieced together the circuits and synapses responsible for learning in Aplysia Californica, and then the molecules and the genes. His critics were silenced when the same molecules and genes found in Aplysia were also found to be involved in memory in rodents—not simply in reflexive types of learned responses, but also in complex cognitive memories involving the hippocampus, a brain region critical for conscious memory in humans.

When I entered the field of neuroscience, Kandel was already a major figure. His approach influenced me considerably as I searched for a way to study emotion in the brain, a topic that was then neglected. On the basis of his pioneering work, it had become a given in the field that the way to relate behavior to biology was by (1) characterizing the behavior, (2) identifying the circuit that controlled the behavior, and (3) determining the cellular and molecular mechanisms that allow the circuit to achieve its control over the behavior. These “what,” “where,” and “how” questions seem so straightforward today, but I doubt this would have been the case had Kandel not shown how following such an approach so systematically could be so successful.