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last update on April 1st 2012

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Coherent Theta Oscillations and Reorganization of Spike Timing in the Hippocampal- Prefrontal Network upon Learning

Karim Benchenane, Adrien Peyrache, Mehdi Khamassi, Patrick L. Tierney, Yves Gioanni, Francesco P. Battaglia and Sidney I. Wiener
Neuron 66, 921-936, June 24, 2010

To study the interplay between hippocampus and medial prefrontal cortex (Pfc) and its importance for learning and memory consolidation, we measured the coherence in theta oscillations between these two structures in rats learning new rules on a Y maze. Coherence peaked at the choice point, most strongly after task rule acquisition. Simultaneously, Pfc pyramidal neurons reorganized their phase, concentrating at hippocampal theta trough, and synchronous cell assemblies emerged. This synchronous state may result from increased inhibition exerted by interneurons on pyramidal cells, as measured by cross-correlation, and could be modulated by dopamine: we found similar hippocampal- Pfc theta coherence increases and neuronal phase shifts following local administration of dopamine in Pfc of anesthetized rats. Pfc cell assemblies emerging during high coherence were preferentially replayed during subsequent sleep, concurrent with hippocampal sharp waves. Thus, hippocampal/ prefrontal coherence could lead to synchronization of reward predicting activity in prefrontal networks, tagging it for subsequent memory consolidation.

Selective suppression of hippocampal ripples impairs spatial memory

G. Girardeau , K. Benchenane, S.I. Wiener, G. Buzsáki & M.B. Zugaro
Nature Neuroscience (2009) 12, 1222-3.

Sharp wave-ripple (SPW-R) complexes in the hippocampus-entorhinal cortex are believed to be important for transferring labile memories from the hippocampus to the neocortex for long-term storage. We found that selective elimination of SPW-Rs during post-training consolidation periods resulted in performance impairment in rats trained on a hippocampus-dependent spatial memory task. Our results provide evidence for a prominent role of hippocampal SPW-Rs in memory consolidation.

 

Replay of rule-learning related neural patterns in the prefrontal cortex during sleep

Adrien Peyrache, Mehdi Khamassi, Karim Benchenane, Sidney I Wiener & Francesco P. Battaglia
Nature Neuroscience 2009 Jul;12(7):919-26.

Slow-wave sleep (SWS) is important for memory consolidation. During sleep, neural patterns reflecting previously acquired information are replayed. One possible reason for this is that such replay exchanges information between hippocampus and neocortex, supporting consolidation. We recorded neuron ensembles in the rat medial prefrontal cortex (mPFC) to study memory trace reactivation during SWS following learning and execution of cross-modal strategy shifts. In general, reactivation of learning-related patterns occurred in distinct, highly synchronized transient bouts, mostly simultaneous with hippocampal sharp wave/ripple complexes (SPWRs), when hippocampal ensemble reactivation and cortico-hippocampal interaction is enhanced. During sleep following learning of a new rule, mPFC neural patterns that appeared during response selection replayed prominently, coincident with hippocampal SPWRs. This was learning dependent, as the patterns appeared only after rule acquisition. Therefore, learning, or the resulting reliable reward, influenced which patterns were most strongly encoded and successively reactivated in the hippocampal/prefrontal network.

 
Communiqué CNRS Article PUBMED
 

Recent publications

La Simplexité
(in french only, September)

« La simplexité, telle que je l'entends, est l'ensemble des solutions trouvées par les organismes vivants pour que, malgré la complexité des processus naturels, le cerveau puisse préparer l'acte et en projeter les conséquences. Ces solutions sont des principes simplificateurs qui permettent de traiter des informations ou des situations, en tenant compte de l'expérience passée et en anticipant l'avenir. Ce ne sont ni des caricatures, ni des raccourcis ou des résumés. Ce sont de nouvelles façons de poser les problèmes, parfois au prix de quelques détours, pour arriver à des actions plus rapides, plus élégantes, plus efficaces. » (A. B.)

Comme le démontre Alain Berthoz dans ce livre profondément original, faire simple n'est jamais facile ; cela demande d'inhiber, de sélectionner, de lier, d'imaginer pour pouvoir ensuite agir au mieux.

Et si, à notre tour, nous nous inspirions du vivant pour traiter la complexité qui nous entoure ?

 

Neurobiology of "Umwelt"
How Living Beings Perceive the World
Series: Research and Perspectives in Neurosciences
Berthoz, Alain; Christen, Yves (Eds.) 2009, XII, 158 p. 22 illus.,
ISBN: 978-3-540-85896-6

Phenomenology and Physiology of Action - Phénoménologie et physiologie de l'action

Under the direction of Alain Berthoz et Jean-Luc Petit - Eds. O. Jacob (Septembre 2006)

Philosophers and scientists are two groups that tend to ignore one another, each pursuing its own work as if the other did not exist — though they may, in fact, be working on the same subjects (space, time, movement, perception, etc.). For once, a scientist and a philosopher have rallied their efforts in an effort to understand how our brain interacts with the world. Does the brain behave as a calculator, combining sense data before deciding how to act? Or does it behave as an emulator endowed with innate models of the world, which it corrects according to the results of experiences obtained by the senses?

More

Head direction cells and the neural mechanisms of spatial orientation

Head direction cells and the neural mechanisms of spatial orientation

Edited by Sidney I. Wiener et Jeffrey S. Taube (July 2005)

Head direction cells -- neurons that fire only when an animal orients its head in a certain direction -- are found in several different brain areas, with different neurons selective for different head orientations; they are influenced by landmarks as well as motor and vestibular information concerning how the head moves through space. These properties suggest [...]

More

 

Les espaces de l'Homme
The Spaces of Man - Les Espaces de l'homme

Under the direction of Alain Berthoz et Roland Recht - Eds. O. Jacob (Juin 2005)

Quels rapports l'homme entretient-il avec ses espaces ? Autour de cette question, un symposium du Collège de France a réuni des mathématiciens et des physiciens, des physiologistes et des psychologues, des anthropologues et des géographes, des historiens de l'art et de la religion, des architectes, un homme de théâtre et un astronaute [...]

More in french

 

L'autisme
Autism - L' Autisme - De la recherche à la pratique

Publication des actes du Congrès tenu au Collège de France sur l'autisme. Eds. O. Jacob (Mai 2005)

L'autisme touche des dizaines de milliers de personnes en France. Ce livre témoigne des progrès accomplis dans la compréhension des aspects génétiques, neurologiques et cognitifs de cette maladie, et des handicaps qu'elle entraîne. La grande diversité de ses symptômes, notamment les troubles de la communication et de la socialisation, rend difficiles son diagnostic et son traitement. Se pose également le problème de la prise en charge des enfants et du soutien de leur famille dans une société mal préparée à les accueillir [...]

More in french

   

 

Links of cognitive neurosciences and biology in Paris

 

 

Laboratoire de Physiologie de la Perception et de l'Action

UMR 7152 Collège de France - CNRS

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