Collège de France

About: Collège de France is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Receptor. The organization has 6541 authors who have published 11983 publications receiving 648742 citations. The organization is also known as: College de France.

The neural basis of egocentric and allocentric coding of space in humans: a functional magnetic resonance study

Abstract: The spatial location of an object can be represented in the brain with respect to different classes of reference frames, either relative to or independent of the subject's position. We used functional magnetic resonance imaging to identify regions of the healthy human brain subserving mainly egocentric or allocentric (object-based) coordinates by asking subjects to judge the location of a visual stimulus with respect to either their body or an object. A color-judgement task, matched for stimuli, difficulty, motor and oculomotor responses, was used as a control. We identified a bilateral, though mainly right-hemisphere based, fronto-parietal network involved in egocentric processing. A subset of these regions, including a much less extensive unilateral, right fronto-parietal network, was found to be active during object-based processing. The right-hemisphere lateralization and the partial superposition of the egocentric and the object-based networks is discussed in the light of neuropsychological findings in brain-damaged patients with unilateral spatial neglect and of neurophysiological studies in the monkey.

Noncommutative Manifolds the Instanton Algebra and Isospectral Deformations

Abstract: We give new examples of noncommutative manifolds that are less standard than the NC-torus or Moyal deformations of $\Rb^n$. They arise naturally from basic considerations of noncommutative differential topology and have non-trivial global features. The new examples include the instanton algebra and the NC-4-spheres $S^4_{\theta}$. The noncommutative algebras $\Ac=C^{\ify} (S^{4}_{\theta})$ of functions on NC-spheres are solutions to the vanishing, $ {\rm ch}_j (e) = 0, j = \g_5$, where $<$ is the projection on the commutant of $4 \ts 4$ matrices. Finally, we show that any compact Riemannian spin manifold whose isometry group has rank $r \geq 2$ admits isospectral deformations to noncommutative geometries.

The ontogeny of the neural crest in avian embryo chimaeras.

Abstract: The migration and subsequent development of autonomic ganglion cell precursors can be followed in suitably constructed chimaeric quail-chick embryos, thanks to the distinctive structures of quail and chick interphase nuclei. The decisive role of environmental factors arising from non-neuronal tissues on the chemical differentiation of neurones was demonstrated together with the lability of their phenotype during ontogeny.