Javier DeFelipe is Professor at the Cajal Institute (CSIC). He was born in Madrid in 1953, received the B.S. and M.S. degrees in Biology from the Universidad Complutense (Madrid) in 1975 and 1977, respectively, and the Ph.D. degree in 1979, from the same University, under the supervision of Dr. José Rodrigo at the Cajal Institute. After postdoctoral training (1980-1983) at the the Cajal Institute with Dr. Alfonso Fairén and Dr. Facundo Valverde, he obtained a Fogarty Fellowship (NIH) to work with Dr. Edward Jones (1983-1984) at the Washington University School of Medicine, St. Louis (USA). From 1984 to 1985 he was appointed as a Visiting Scientist, in the laboratory of Dr. Jones at the University of California (Irvine). In 1986, DeFelipe obtained a Tenured in Neuroscience at the Cajal Institute. In 2000, he was appointed as Research Scientist, and in 2004 as Full Professor in the same institution. His research focuses on the microorganization of the normal cerebral cortex (including hippocampus) in various species and on the alterations of cortical circuits in epilepsy and Alzheimer disease. The variety and excellence of his contributions to the field is reflected by the frequent citation of his work in the scientific literature and by the numerous lectures delivered world-wide. He has also been the recipient of a series of awards and honors. Another of his principal interest is the study of the history of our current understanding of cortical organization and function. In particular, he is interested in the roots of cortical histology and circuitry.