Eric Kandel - Medical School and Early Research

Medical School and Early Research

In 1952 he started at the New York University Medical School. By graduation he was firmly interested in the biological basis of the mind. During this time he met his future wife, Denise Bystryn. Kandel was first exposed to research in Harry Grundfest's laboratory at Columbia University. Grundfest was known for using the oscilloscope to demonstrate that action potential conduction velocity depends on axon diameter. The researchers Kandel interacted with were contemplating the technically challenging idea of intracellular recordings of the electrical activity of the relatively small neurons of the vertebrate brain.

After starting his neurobiological work in the difficult thicket of the electrophysiology of the cerebral cortex, Kandel was impressed by the progress that had been made by Stephen Kuffler using a much more experimentally accessible system: neurons isolated from marine invertebrates. After becoming aware of Kuffler's work in 1955, Kandel graduated from medical school and learned from Stanley Crain how to make microelectrodes that could be used for intracellular recordings of relatively large crayfish giant axons.

Karl Lashley, a well-known American neuropsychologist, had tried but failed to identify an anatomical locus for memory storage in the cortex at the surface of the brain. When Kandel joined the Laboratory of Neurophysiology at the National Institutes of Health in 1957, William Beecher Scoville and Brenda Milner had recently described the patient HM, who had lost explicit memory storage following removal of the hippocampus. Kandel took on the task of performing electrophysiological recordings of hippocampal pyramidal neurons. Working with Alden Spencer, electrophysiological evidence was found for action potentials in the dendritic trees of hippocampal neurons. They also noticed the spontaneous pace-maker-like activity of these neurons and a robust recurrent inhibition in the hippocampus. With respect to memory, there was nothing in the general electrophysiological properties of hippocampal neurons that suggested why the hippocampus was special for explicit memory storage.

Kandel began to realize that memory storage must rely on modifications in the synaptic connections between neurons and that the complex connectivity of the hippocampus did not provide the best system for study of the detailed function of synapses. Kandel was aware that comparative studies of behavior, such as those by Konrad Lorenz, Niko Tinbergen, and Karl von Frisch had revealed conservation of simple forms of learning across all animals. Kandel felt it would be productive to select a simple animal model that would facilitate electrophysiological analysis of the synaptic changes involved in learning and memory storage. He believed that, ultimately, the results would be found to be applicable to humans. This decision was not without risks since many senior biologists and psychologists believed that nothing useful could be learned about human memory by studying invertebrate physiology.

In 1962, after completing his residency in psychiatry, Kandel went to Paris to learn about the marine mollusc Aplysia californica from Ladislav Tauc. Kandel had realized that simple forms of learning such as habituation, sensitization, classical conditioning, and operant conditioning could readily be studied with ganglia isolated from Aplysia. "While recording the behavior of a single cell in a ganglion, one nerve axon pathway to the ganglion could be stimulated weakly electrically as a conditioned stimulus, while another pathway was stimulated as an unconditioned stimulus, following the exact protocol used for classical conditioning with natural stimuli in intact animals." Electrophysiological changes resulting from the combined stimuli could then be traced to specific synapses. In 1965 Kandel published his initial results, including a form of pre-synaptic potentiation that seemed to correspond to a simple form of learning.