Free In Search of Memory: The Emergence of a New Science of Mind by Eric R. Kandel

school, after graduating from Harvard.
    That summer of 1951 I shared a house with four men who became lifelong friends: Henry Nunberg, Anna’s cousin and the son of another great psychoanalyst, Herman Nunberg; Robert Goldberger; James Schwartz; and Robert Spitzer. A few months later, based on that single chemistry course and my overall college record, I was accepted at New York University Medical School, with the proviso that I complete the remaining course requirements before enrolling in the fall of 1952.
    I entered medical school dedicated to becoming a psychoanalyst and stayed with that career plan through my internship and residency in psychiatry. By my senior year in medical school, however, I had become very interested in the biological basis of medical practice. I decided I had to learn something about the biology of the brain. One reason was that I had greatly enjoyed the course on the anatomy of the brain that I had taken during my second year in medical school. Louis Hausman, who taught the course, had each of us build out of colored clays a large-scale model that was four times the size of the human brain. As my classmates later described it in our yearbook, “The clay model stirred the dormant germ of creativity, and even the least sensitive among us begat a multihued brain.”
    Building this model gave me my first three-dimensional view of how the spinal cord and the brain come together to make up the central nervous system (figure 3–2). I saw that the central nervous system is a bilateral, essentially symmetrical structure with distinct parts, each bearing an intriguing name, such as hypothalamus, thalamus, cerebellum, or amygdala. The spinal cord contains the machinery needed for simple reflex behaviors. Hausman pointed out that by examining the spinal cord, one can understand in microcosm the overall purpose of the central nervous system. That purpose is to receive sensory information from the skin through bundles of long nerve fibers, called axons, and to transform it into coordinated motor commands that are relayed to the muscles for action through other bundles of axons.
    As the spinal cord extends upward toward the brain, it becomes the brain stem (figure 3–3), a structure that conveys sensory information to higher regions of the brain and motor commands from those regions downward to the spinal cord. The brain stem also regulates attentiveness. Above the brain stem lie the hypothalamus, the thalamus, and the cerebral hemispheres, whose surfaces are covered by a heavily wrinkled outer layer, the cerebral cortex. The cerebral cortex is concerned with higher mental functions: perception, action, language, and planning. Three structures lie deep within it: the basal ganglia, the hippocampus, and the amygdala (figure 3–3). The basal ganglia help regulate motor performance, the hippocampus is involved with aspects of memory storage, and the amygdala coordinates autonomic and endocrine responses in the context of emotional states.

     
    3–2 The central and peripheral nervous systems. The central nervous system, which consists of the brain and the spinal cord, is bilaterally symmetrical. The spinal cord receives sensory information from the skin through bundles of long axons that innervate the skin. These bundles are called peripheral nerves. The spinal cord also sends motor commands to muscles through the axons of the motor neurons. These sensory receptors and motor axons are part of the peripheral nervous system.
     
    It was hard to look at the brain, even a clay model of it, without wondering where Freud’s ego, id, and superego were located. A keen student of the anatomy of the brain, Freud had written repeatedly about the relevance of the biology of the brain to psychoanalysis. For example, in 1914 he wrote in his essay “On Narcissism”: “We must recollect that all of our provisional ideas in psychology will presumably one day be based on an organic substructure.” In 1920 Freud again noted,