Kandel's seminal work with the sea slug Aplysia, a creature with relatively few nerve cells and clearly delineated behavioral circuitry compared with vertebrates, demonstrated fundamental ways in which nerve cells alter their responsiveness to chemical signals to produce a coordinated change in behavior. The work has been essential not only for our understanding of the basic processes of learning and memory, but also for highlighting many of the cellular processes that are targets of psychoactive drugs.

Kandel's research has been pivotal in relating three psychologically defined forms of learning-habituation, sensitization, and classical conditioning-to subcellular processes and intercellular signaling. In his studies, Dr. Kandel found that simple behaviors could be accounted for by distinctive sets of nerve cells connected in invariant circuits. Dr. Kandel and colleagues found that learning produces changes behavior not by altering basic circuitry, but by adjusting the strength of particular connections between nerve cells. Dr. Kandel and co-workers also defined sets of genes and proteins that stabilize synaptic connections and trigger growth of new ones. More recently, Kandel's lab has extended this approach from simple forms of memory in the Aplysia to more complex forms of spatial learning in mammals.

In response to calls for an integrated approach to understanding the biological basis of behavior, Columbia established the Center for Neurobiology and Behavior with Kandel as its director in 1975. The Center, comprising faculty with appointments in the departments of Anatomy and Cell Biology, Biochemistry and Molecular Biophysics, Genetics and Development, Neurology, Pathology, Pharmacology, Physiology and Cellular Biophysics, and Psychiatry, applies research in these various disciplines to understanding the cellular and molecular basis of behavior, perception, and learning.