Giulio Tononi

Credentials: MD, PHD

Position title: Professor, Director of WISC, Director of Research


Website: Giulio Tononi's website

9601 Uw Psychiatric Inst & Clinics
6001 Research Park Blvd
Madison, WI 53719


MD University of Pisa, Italy

PHD Scuola Normale Superiore Pisa

Research Summary

My scientific work has focused on two main themes: 1) the functions and mechanisms of sleep; and 2) the neural substrate of consciousness.

Research Detail

The work on sleep is centered around a comprehensive hypothesis about its functions—the synaptic homeostasis hypothesis (SHY). SHY holds that sleep serves to renormalize synaptic strength, counterbalancing a net increase of synaptic strength due to plasticity during wakefulness. The sleep-dependent down-selection, promoted by the systematic reactivation of neural circuits when off-line, is critical for desaturating the ability to learn, consolidating memories, and increasing signal-to-noise in the brain. In short, according to SHY, sleep is the price to pay for plasticity during wakefulness. Together with my long-term collaborator, Dr. Chiara Cirelli, we have been providing genetic, molecular, electrophysiological, and computational support for SHY. One of the implications of SHY is that a progressive increase in synaptic strength due to extended wake or intense learning will trigger local sleep during wake, a prediction that has been confirmed both in rodents and in humans. We are now focusing on the circuit and mechanisms that bring about local sleep in wake, which may underlie mental fatigue.

The work on consciousness has centered on the development of the integrated information theory (IIT), a comprehensive theory of what consciousness is, its neural substrate, what determines its quantity and quality, and how it can be measured independent of report. IIT provides an account of why certain parts of the brain are critical for consciousness, why consciousness vanishes during deep slow wave sleep and seizures despite continuing neural activity, and how unconscious processes interact with conscious ones. IIT has led to the development of measures of information integration that can be employed to assess the quantity of consciousness in healthy humans and, by extrapolation, in unresponsive patients. The theory is supported by theoretical work, computational models, and experimental approaches that use high-density EEG (hd-EEG) and transcranial magnetic stimulation (TMS).