Mémoire spatiale et navigation

Our team was founded in 1989 when Dr Wiener arrived in the laboratory directed by Alain Berthoz (which he continued for the following 20 years). (Wiener had previously carried out post-doctoral studies for three year with Prof Howard Eichenbaum in Boston , MA , USA ). The principal focus is on the relation between cognitive functions such as spatial learning and memory and electrical activity in neurons, ensembles of neurons and neural networks, as measured with chronically implanted electrodes. The experiments are carried out by analysing recordings from behaving animals as they performed tasks requiring specific types of cognitive processing. Much of the work is centered on a popular experimental model for abstract representations in the brain - the place and head direction cells in the hippocampal system and related areas. We have studied how these areas elaborate this activity and also how brain areas downstream from the hippocampus (ventral striatum, prefrontal cortex) exploit it for behavior and cognition. The role of sleep and associated brain oscillations in off-line memory consolidation is of particular interest. Effects of neuromodulatory influences from Locus coeruleus and Ventral tegmental area are also investigated.

Neural bases of learning and memory.
Neural bases of spatial orientation behavior.
Neuromodulatory systems especially noradrenaline and dopamine.
Brain oscillations and memory consolidation.
Brain rhythms, cell assemblies and neuronal sequences.

Two projects, ICEA and BACS, are Integrative Projects (IPs) in the European Community (EC) Information Society Technologies (IST) Cognitive Systems (CogSys)
program (http://cordis.europa.eu/ist/cognition/index.html).

ICEA www.iceaproject.eu IST 027819 ICEA (Integrating Cognition, Emotion and Autonomy) is a four-year project, funded by IST Cognitive Systems Unit . The ICEA Project is focused on brain-inspired cognitive architectures, robotics and embodied cognition, bringing together cognitive scientists, neuroscientists, psychologists, computational modelers, roboticists and control engineers.

The primary aim of the project is to develop a cognitive systems architecture integrating cognitive, emotional and bioregulatory (self-maintenance) processes , based on the architecture and physiology of the mammalian brain .

In ICEA we will develop a new generic autonomous agent architecture based on the extraction of control design patterns from bioregulatory, emotional and cognitive control loops based on the architecture and physiology of the rat brain. (from the Web site)

Our team's role in ICEA is to study the neural activity and ensemble dynamics underpinning cognitive functions in rats as they acquire, recall and choose between complementary strategies for goal directed action. Recordings involve hippocampus, three parts of striatum, prefrontal cortex and amygdala in order to determine coordination between different structures during shifts in strategy.

“Contemporary robots and other cognitive artifacts are not yet ready to autonomously operate in complex real world environments. One of the major reasons for this failure in creating cognitive situated systems is the difficulty in the handling of incomplete knowledge and uncertainty. By taking up inspiration from the brains of mammals, including humans, the BACS project will investigate and apply Bayesian models and approaches in order to develop artificial cognitive systems that can carry out complex tasks in real world environments. The Bayesian approach will be used to model different levels of brain function within a coherent framework, from neural functions up to complex behaviors. The Bayesian models will be validated and adapted as necessary according to neuro-physiological data from rats and humans and through psychophysical experiments on humans. The Bayesian approach will also be used to develop four artificial cognitive systems concerned with (i) autonomous navigation, (ii) multi-modal perception and reconstruction of the environment, (iii) semantic facial motion tracking, and (iv) human body motion recognition and behavior analysis. The conducted research shall result in a consistent Bayesian framework offering enhanced tools for probabilistic reasoning in complex real world situations. The performance will be demonstrated through its applications to driver assistant systems and 3D mapping, both very complex real world tasks. (from the Web site)

In BACS we examine the adequacy of a Bayesian approach for describing spatial navigation processes at the levels of

• How the co-activation of a subset of neurons in a single neuronal ensemble activity predicts future activation patterns over time and behavioral states.

Specifically, our team p rovides neurophysiological as well as behavioral data to test (and eventually improve) hypotheses about Bayesian inference. This involves a data base from hundreds of recording experiments in several types of mazes.

Another project NeuroProbes is an IP in the EC IST program “Integrating and strengthening the European research area (2002-2006) ”

NeuroProbes http://naranja.umh.es/~np/index.php NeuroProbes is a European Project aiming at developing a system platform for the scientific understanding of cerebral systems, and for the treatment of the associated diseases. The work will produce an integrated tool that combines multiple functions to allow electrical as well as chemical sensing and stimulation of neurons. Fourteen partners, from all over Europe and both from academic and industrial worlds, form the NeuroProbes consortium.

The aim of the proposed research is to develop a system platform that will allow an extremely wide series of innovative diagnostic and therapeutic measures for the treatment and for the scientific understanding of cerebral systems and associated diseases. The proposed work will enable a new integrated tool that combines multiple functions to allow electrical recording and stimulation as well as chemical sensing and stimulation. The resulting potential is expected to lead to a new era of work in the field of fundamental, scientific, as well as clinical brain research. (from the Web site)

• Validation of the developed fixed arrays of silicon-based microelectrodes arrays through recording experiments in rat hippocampal system

• High population sampling recordings from hippocampal neurons will be tested to determine the nature of functional coupling between ‘place cells' representing overlapping places in the environment, and their dynamic changes over time such as Hebbian-like plasticity processes.

• Establish relationship between local field potentials and activity in neurons of the hippocampal ensembles

• Development of spike discrimination infrastructure for novel configurations for high-density recording in brain micro-domains

Peyrache A., Khamassi M., Benchenane K., Wiener S.I., Battaglia F.P. (2009) Replay of rule-learning related neural patterns in the prefrontal cortex during sleep. Nat Neurosci. 12(7):919-26.

Ramadan W., Eschenko O., Sara S.J. (2009) Hippocampal sharp wave/ripples during sleep for consolidation of associative memory. PLoS One. Aug 20;4(8):e6697.

Girardeau G. , Benchenane K., Wiener S.I. , Buzsáki G., Zugaro M.B. (2009) Selective suppression of hippocampal ripples impairs spatial memory. Nat Neurosci. 12(10):1222-3.

Benchenane K., Peyrache A., Khamassi M., Tierney P.L., Gioanni Y., Battaglia F.P., Wiener S.I. (2010) Coherent theta oscillations and reorganization of spike timing in the hippocampal- prefrontal network upon learning. Neuron. Jun 24;66(6):921-36.