Giulio Tononi received his medical degree and specialized in psychiatry at the University of Pisa, Italy. After serving as a medical officer in the Army, he obtained a Ph.D. in neuroscience as a fellow of the Scuola Superiore, based on his work on sleep regulation. From 1990 to 2000 he has been associated with The Neurosciences Institute, first in New York and then in San Diego. He is currently Professor of Psychiatry at the University of Wisconsin, Madison, where he is studying consciousness and its disorders as well as the mechanisms and functions of sleep.

In his work on consciousness, Dr. Tononi has addressed the problem of how the activities of functionally specialized areas of the brain can be integrated to give rise to a unified conscious experience. To this end, he has: (1) constructed large-scale computer models based on the anatomy and physiology of the thalamocortical system to study the mechanisms of information integration; (2) developed theoretical approaches aimed at defining and measuring the integration of information within the nervous system; (3) pioneered experimental approaches aimed at characterizing the neural substrate of conscious experience by using neuroimaging and, more recently, transcranial magnetic stimulation. This work has recently led to the formulation of the information integration theory of consciousness. His group is currently investigating some of the predictions of the theory, with particular emphasis on the breakdown of information integration in various stages of sleep and in brain disorders such as schizophrenia.

In his work on sleep, Dr. Tononi has pioneered the combined use of electrophysiological approaches and molecular biology. In collaboration with Dr. Chiara Cirelli, he has discovered striking differences in the expression of certain genes between sleep and waking and identified molecular markers of these behavioral states. Further studies have uncovered the neurophysiological and molecular mechanisms by which the acquisition of new information by the brain is limited to waking states and does not occur during sleep. Recently, Dr. Cirelli’s and Tononi’s laboratory has demonstrated, based on a variety of behavioral, pharmacological, and molecular criteria, that sleep-like states are present in the fruit fly Drosophila. This finding has opened the way to the genetic dissection of sleep using mutant screening and other powerful tools of genetic manipulation available in Drosophila. Current work using human, rat, and mouse models is aimed at understanding the functions of sleep by focusing on the consequences of sleep and sleep deprivation at the cellular and molecular level. Recently, he has formulated a new hypothesis about the function of sleep, according to which sleep serves synaptic homeostasis. This hypothesis has led to several experimental tests, including the recent demonstration that sleep can be induced on a local basis by learning and plasticity. The synaptic homeostasis hypothesis has implications with respect to the neurobiology of mood disorders and the beneficial but transitory effects of sleep deprivation on depression.

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