Giulio Tononi

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Giulio Tononi (2005)

Giulio Tononi (* Trento , Trentino-South Tyrol ) is an Italian specialist in psychiatry and neuroscientist .

He is a professor of psychiatry at the University of Madison-Wisconsin and heads the Center for Sleep and Consciousness there . Tononi and Chiara Chirelli developed the Synaptic Homeostasis Hypothesis (synaptic homeostasis hypothesis), which states that deep sleep is necessary to restore a basic level of synaptic activity. His second research topic is how consciousness comes about; Tononi developed the Integrated Information Theory for this purpose .

biography

Tononi studied medicine and specialized in psychiatry at the Scuola Superiore Sant'Anna in Pisa . There he also obtained a PhD in neurobiology and received his doctorate on a topic on the regulation of sleep. Before moving to Madison, he conducted research at the Neurosciences Institute in New York and in San Diego.

Synaptic Homeostasis Hypothesis

"Essentially, sleep is the price we have to pay for [neural] plasticity ..."

- G. Tononi and C. Cirelli

According to this theory, information is incorporated into the network structures of nerve cells in the waking state , i.e. H. the strength of the synapses increases, and synaptic reconnections also arise. This happens through the so-called long-term potentiation . In deep sleep (more precisely: in non-REM sleep ) there is a kind of synchronization of certain neuronal groups, which is noticeable through long-wave potentials ( so-called delta waves appear in the EEG ) and is responsible for the strength of the synapse connection and number decreases again (synaptic downscaling). Because only the more potent synapses survive, the important is selected from the unimportant.

Integrated Information Theory

“Everyone knows what consciousness is: it is what disappears every night as soon as we fall into a dreamless sleep and comes back as soon as we wake up or dream. Seen in this way, the term consciousness is synonymous with experience. "

- G. Tononi 2012

According to this theory, awareness arises when there is enough “integrated” information. Tononi makes the following comparison about his concept of integration : In front of a screen that alternately lights up brightly and darkly, both a person and a photodiode , for example in a camera, can recognize the two states. The difference lies in how much information is generated: The photodiode recognizes 'light' or 'dark' and thus generates 1 bit of information. A person distinguishes 'light' not only from 'dark', but also from an enormous number of other possibilities, e.g. B. a red screen, a green screen, a still picture, a sound, a thought etc. While the countless photodiodes of a camera work independently of each other, the human brain makes its distinctions as an integrated system. No matter how hard you try, you cannot reduce the conscious perception of a red apple, for example, to separate sensations of its color and shape. Tononi denotes the extent of integrated information as Φ (Phi); if all individual components work independently of one another, Φ = 0.

Tononi writes: “Using computer simulations [can] show that highly integrated information requires a network that combines functional specialization with functional integration. It is precisely this type of architecture that is characteristic of the thalamocortical system in mammals: Different parts of the cerebral cortex are specialized in different functions: from the level of the cerebral lobes to the areas, the neuron groups, and perhaps even down to the individual neurons. In addition, there is a broad network of connections that allows these parts to interact with one another ... This agrees with the observation that the thalamocortical system is precisely that part of the central nervous system whose severe damage leads to loss of consciousness . Conversely, the value for 'Integrated Information' is low in systems that are built on small, quasi-independent modules. This will be the reason why the cerebellum, despite its immense number of neurons, hardly contributes to the generation of consciousness. "

According to Tononi and Gerald M. Edelman , a reentry mechanism is a unique feature of integration. Reentrant signals within the cerebral cortex or between the cerebral cortex and thalamus are supposed to establish a coherent process of active neurons that is stable overall, although its neural composition is constantly changing. Such self-sustaining dynamic processes within the thalamocortical system are of considerable importance for the understanding of consciousness. In order to maintain conscious experience, the functional cluster must also be highly complex. Such clusters, called flexible or dynamic core structure (dynamic core) by Tononi and Edelman , exist largely, if not exclusively, in the thalamocortical system.

According to the US neuroscientist Christof Koch , IIT can be seen as a scientific form of panpsychism .

Awards

In 2005 Tononi received the NIH Director's Pioneer Award for his work on the mechanisms and functions of sleep; in 2008 he received the David P. White Chair in Sleep Medicine and the Distinguished Chair in Consciousness Science. Tononi was awarded the Zülch Prize for 2015. In 2018 Tononi was awarded the Humboldt Prize. On December 13, 2018, he was awarded the title Leibniz Chair by the Leibniz Institute for Neurobiology in Magdeburg .

Web links

swell

  • G. Tononi: Consciousness as integrated information: a provisional manifesto. In: Biol Bull. 215 (3), 2008 Dec, pp. 216-242. [4]
  • D. Balduzzi, G. Tononi: Integrated information in discrete dynamical systems: motivation and theoretical framework. In: PLoS computational biology. Volume 4, number 6, June 2008, p. E1000091, doi : 10.1371 / journal.pcbi.1000091 , PMID 18551165 , PMC 2386970 (free full text).
  • G. Tononi: An information integration theory of consciousness. In: BMC Neurosci. 5, 2004 Nov 2, p. 42. [5]
  • Giulio Tononi: Phi: A Voyage from the Brain to the Soul. Pantheon Books, 2012, ISBN 978-0-307-90721-9 .

Individual evidence

  1. ↑ a b Giulio Tononi. to: centerforsleepandconsciousness.med.wisc.edu
  2. ^ G. Tononi, C. Cirelli: Sleep function and synaptic homeostasis. (PDF; 305 kB) In: Sleep Medicine Reviews . 10 (1), 2006 Feb, pp. 49-62. Review.
  3. ^ G. Tononi, C. Cirelli: Sleep and synaptic homeostasis: a hypothesis. In: Brain Res Bull. 62 (2), 2003 Dec 15, pp. 143-150.
  4. ↑ Susanne Engelmann: Procedural memory consolidation during sleep and quiet waking periods during the day. (PDF dissertation, Albert-Ludwigs-University Freiburg i. Br. 2010.
  5. ↑ U. Gebhardt: Sleep, little child, sleep! Age-related changes in sleep pattern and length of sleep. In: NZZ. October 27, 2010.
  6. ↑ U. Gebhardt: Sleep: Great cleaning in the head. In: Der Tagesspiegel. November 18, 2010.
  7. ^ A b G. Tononi: Integrated information theory of consciousness: an updated account. In: Arch Ital Biol. 2012 Jun-Sep; 150 (2-3). [1]
  8. ^ G. Tononi: Information integration: its relevance to brain function and consciousness. In: Arch Ital Biol. 148 (3), 2010 Sep, pp. 299-322. [2]
  9. ↑ Gerald M. Edelman, Giulio Tononi, Susanne Kuhlmann-Krieg: How consciousness arises from matter. In: brain and mind. February 20, 2002.
  10. ↑ C. Koch: A "Complex" Theory of Consciousness: Is complexity the secret to sentience, to a panpsychic view of consciousness? In: Scientific American Mind. July / August 2009. [3]
personal data
SURNAME Tononi, Giulio
BRIEF DESCRIPTION Specialist in psychiatry and neuroscientist
DATE OF BIRTH 20th century