LECTURE Friday, 4 April by
Giulio Tononi and Chiara Cirelli
School of Medicine, Department of Psychiatry, University of Wisconsin – Madison, USA
Sleep and the price of plasticity
Giulio Tononi is a psychiatrist and neuroscientist who has held faculty positions in Pisa, New York, San Diego and Madison, Wisconsin, where he is Professor of Psychiatry. Dr. Tononi has developed The integrated information theory of consciousness (IITC) a scientific theory of what consciousness is, how it can be measured, how it is realized in the brain and why it fades when we fall into dreamless sleep and returns when we dream. The theory is being tested with neuroimaging, transcranial magnetic stimulation, and computer models. In 2005, Dr. Tononi received the NIH Director’s Pioneer Award for his work on sleep mechanism and function, and in 2008 he was made the David P. White Chair in Sleep Medicine and is a Distinguished Chair in Consciousness Science.
Chiara Cirelli (MD, PhD, University of Pisa) is Professor of Psychiatry at the University of Wisconsin, Madison. Her research aims at understanding the function of sleep and clarifying the functional consequences of sleep loss. Her team uses a combination of different approaches, from genetics in fruit flies to whole-genome expression profiling in invertebrates and mammals, to behavioral and EEG analysis in mice and rats. The first approach exploits Drosophila genetics to identify genes involved in sleep regulation. Overall, it appears that sleep need is related to synaptic plasticity, an idea that is being tested in several animal models. The second approach involves whole-genome profiling to identify the genes whose expression changes in the brain in sleep relative to wakefulness. In rats, she found that hundreds of genes are differentially expressed in the brain during sleep and wake.
The results of these and other studies have prompted a new hypothesis about the functions of sleep. C. Cirelli and G. Tononi have hypothesized that the amount of synaptic potentiation that occurs during waking is a major determinant of sleep intensity, and that sleep is needed to down-regulate synaptic weight. The synaptic homeostasis hypothesisis being tested at several different levels in a joint effort, ranging from computer simulations and high-density EEG and transcranial magnetic stimulation experiments in humans to molecular, behavioral, and electrophysiological experiments in flies and rodents.
Johan F. Storm, On behalf of Forum for bevissthetsforskning