Harvard Medical School researchers Vadim Bolshakov, Evgeny Tsvetkov, and Bill Carlezon, based at McLean Hospital, reported with colleagues in the April 11, 2002 issue of the journal Neuron that they have found clear evidence of cause and effect between learning and long-term changes in the brain. Their research focused on how learned fear made changes in the brains of rats. “I think that this is the first really important causal link,” said Eric Kandel, a scientist at Columbia University College of Physicians and Surgeons who colloborated in the research. Kandel won the Nobel Prize in physiology or medicine in 2000. Bolshakov and Carlezon are Harvard Medical School assistant professors of psychiatry. Tsvetkov, who is first author on the study, is a Harvard Medical School research fellow in psychiatry.