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Séminaire impromptu - George DragoiInternal representation of spatial information by hippocampal cellular assemblies

Abstract :

George Dragoi  du MIT  invité par Nora Abrous du Neurocentre Magendie

Internal representations about the external world can be driven by the external stimuli or can be internally-generated in their absence.
It has been a matter of debate whether novel stimuli from the external world are instructive over the brain network to create de novo representations or, alternatively, they are selecting from existing pre-representations hosted in preconfigured brain networks.
The hippocampus is a brain area necessary for normal internally-generated spatial-temporal representations and its dysfunctions have resulted in anterograde amnesia, impaired imagining of new experiences, and hallucinations. The compressed temporal sequence of place cell activity in the rodent hippocampus serves as an animal model of internal representation of the external space. Based on my recent results on the phenomenon of novel place cell sequence "preplay", I propose that the place cell sequence of a future novel spatial experience can be determined by a selection of a set of cellular firing sequences from a repertoire of pre-existing temporal firing sequences in the hippocampal network.
Conceptually, this indicates that novel stimuli from the external world select from their pre-representations rather than create entirely de novo our internal representations of the world.

Selected publications

Dragoi, D. and Tonegawa, S. Distinct preplay of multiple novel spatial experiences in the rat. PNAS. 110 (22): 9100-9105 (2013).

Dragoi, G. and Tonegawa, S. Preplay of future place cell sequences by hippocampal cellular assemblies. Nature 469: 397-403 (2011).

Internal operations in the hippocampus: single cell and ensemble temporal coding.
Dragoi G.
Front Syst Neurosci. 2013 Aug 29;7:46. doi: 10.3389/fnsys.2013.00046. No abstract available.

Post it

 “Preplay of future place cell sequences by hippocampal cellular assemblies,” by George Dragoi and Susumu Tonegawa.
Nature, 22 December, 2010.

In the current work, research scientist George Dragoi and Susumu Tonegawa, Picower Professor of Biology and Neuroscience and director of the RIKEN-MIT Center for Neural Circuit Genetics, found that some of the sequences of place cells in mice’ brains that fired during a novel spatial experience such as running a new maze had already occurred while the animals rested before the experience. Read more...