François Clarac

17 mai 2013

INT, équipe P3M, Marseille

De Sherrington au "Blue Brain Project"

Last year opened in Marseille at the Timone Campus a new Institute of Neurosciences, the INT. If it is mainly due to its new director Guillaume Masson, to its deputy director Laurent Vinay, to their different team leaders and to their researchers, adminitrative and technical assistants, it is also the result of the importance of the Neurosciences in Marseille with its different campus (the "North Hospital", Timone Campus, Ste Marguerite, Joseph Aiguier and Luminy... developed by their leaders Morin, Paillard, Naquet, Requin, Dussardier, Rochat, Pailhous, Tyc-Dumont, Mei...) This seminar will summarize one century of new concepts that have been successively developed in different disciplines such as psychophysiology, neurochemistry, cybernetics, cognitive sciences, computational neuroscience, .... Major data must be mentioned :
- The basic and fundamental works in neuroanatomy by Golgi and Ramon y Cajal and in neurophysiology by Sherrington, Adrian, Erlanger and Gasser and in behavioral neuroscience by Pavlov and Skinner...
- The first mathematical model of a neuron was proposed by McCulloch and Pitts in 1943. At that time the complexity of the brain was compared with a computer. Between 1942 and 1953, the "Macy Conferences" have been organized in New York with a group of interdisciplinary scientists to elaborate a general science of the "Mind functioning".
- Eccles, a major physiologist of the XXth century, made the first intracellular recording of a spinal motoneuron in 1951.
- The original Falck-Hillarp (1957) method provided the possibility to understand and to follow along the brain the organization of the three amine pathways, the serotoninergic, the dopaminergic and the noradrenergic pathways.
- Shik and Orlovsky in the 1960s obtained an automatic locomotion with decerebrate cats walking above a treadmill. This was the origin leading to a new concept of programmed activity largely developed later by Grillner with the lamprey.
- Kandel, who published in 1970 three articles in Science, defined two important opposite notions, "habituation" that is a reduction of the response after the repetition of a given stimulus and "sensitization" that is an increase of the response produced by applying, for instance, a noxious stimulus to the tail of the sea slug Aplysia. The activated sensory neurons facilitate interneurons that stimulate the pathway from the siphon to the motor neurons.
- In two articles published in J. Physiol. (1973) Bliss, Lomo and Gardner-Medwin demonstrated in the hippocampus of the rabbit, that a stimulation at 10-15/sec during several seconds is enough to increase an excitatory answer in a postsynaptic cell, during 30 mns to 10 hours.
- Between 1970s and 1980s, Evarts and Georgopoulos followed by Riehle and Requin recorded cortical neurons of the monkey motor cortex that are active several hundred ms. before an action.
- In 1996, Rizzolatti defined the concept of mirror neurons that concerned the cortical F5 sector where hand actions are represented. A new study was carried out on the properties of neurons located in the lateral part of F5 where most neurons are related to mouth actions. In conclusion, we can say that the development of Neuroscience has been progressive and regular with about 35000 publications per year ! In the future, very exciting projects are proposed, one is by Henry Markram who hypothesized that the first "virtual brain" will be functional around 2018. The different laboratories of Marseille and in particular the INT will actively participate to various other exciting neuroscience projets !

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