Modern brain imaging is revolutionizing the study of brain function in health and disease. Few realize that its origins began with a pioneering study in the nineteenth century by an Italian scientist, Angelo Mosso, of several subjects brought to him with head injuries that exposed their brains to direct observation. He took advantage of this opportunity to observe for the first time changes in cerebral blood flow in relation to different behaviors, the same changes that are the basis for the measurements underlying modern methods. Although Mosso was widely recognized for this highly original study by his contemporaries, through a German translation in 1881, there has never been a translation through which his magnificent achievement could be recognized in English. His rightful role as the pioneer in brain imaging has thus not been recognized. This unique volume corrects that deficiency. Through it, the modern reader, whether an expert in the field or an interested scientist or member of the public, can gain a new perspective on the remarkable insights Mosso gained into how behaviors as subtle as thinking about a subject or feeling an emotion can produce the changes in pulsations of the brain that he observed. The special features of this volume begin with a brief summary of Mosso's life. Two pioneers of modern brain imaging, Marcus Raichle and Gordon M. Shepherd, then provide an extensive commentary that succinctly summarizes Mosso's work and explains its relevance to modern methods. The authors not only emphasize Mosso's role as a pioneer in brain imaging, but also through this study as a pioneer in the eventual rise of cognitive neuroscience. The English translation then follows, together with all of the plates and illustrations of the original volume. The result is a classic of neuroscience now available for wide appreciation by neuroscientists, neurologists, psychologists, psychiatrists, historians of science and medicine, and the general public.