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Sainte-Foy-lès-Lyon, France

Lazard D.S.,French Institute of Health and Medical Research | Lazard D.S.,University of Lyon | Collette J.-L.,University of Lyon | Perrot X.,University of Lyon | Perrot X.,Lyon Neuroscience Research Center
Laryngoscope | Year: 2012

Language processing from the cochlea to auditory association cortices shows side-dependent specificities with an apparent left hemispheric dominance. The aim of this article was to propose to nonspeech specialists a didactic review of two complementary theories about hemispheric asymmetry in speech processing. Starting from anatomico-physiological and clinical observations of auditory asymmetry and interhemispheric connections, this review then exposes behavioral (dichotic listening paradigm) as well as functional (functional magnetic resonance imaging and positron emission tomography) experiments that assessed hemispheric specialization for speech processing. Even though speech at an early phonological level is regarded as being processed bilaterally, a left-hemispheric dominance exists for higher-level processing. This asymmetry may arise from a segregation of the speech signal, broken apart within nonprimary auditory areas in two distinct temporal integration windows-a fast one on the left and a slower one on the right-modeled through the asymmetric sampling in time theory or a spectro-temporal trade-off, with a higher temporal resolution in the left hemisphere and a higher spectral resolution in the right hemisphere, modeled through the spectral/temporal resolution trade-off theory. Both theories deal with the concept that lower-order tuning principles for acoustic signal might drive higher-order organization for speech processing. However, the precise nature, mechanisms, and origin of speech processing asymmetry are still being debated. Finally, an example of hemispheric asymmetry alteration, which has direct clinical implications, is given through the case of auditory aging that mixes peripheral disorder and modifications of central processing. © 2011 The American Laryngological, Rhinological, and Otological Society, Inc. Source

Powell G.,University of Cardiff | Sumner P.,University of Cardiff | Bompas A.,Lyon Neuroscience Research Center
Journal of vision | Year: 2015

The question of whether eye movements influence afterimage perception has been asked since the 18th century, and yet there is surprisingly little consensus on how robust these effects are and why they occur. The number of historical theories aiming to explain the effects are more numerous than clear experimental demonstrations of such effects. We provide a clearer characterization of when eye movements and blinks do or do not affect afterimages with the aim to distinguish between historical theories and integrate them with a modern understanding of perception. We found neither saccades nor pursuit reduced strong afterimage duration, and blinks actually increased afterimage duration when tested in the light. However, for weak afterimages, we found saccades reduced duration, and blinks and pursuit eye movements did not. One interpretation of these results is that saccades diminish afterimage perception because they cause the afterimage to move unlike a real object. Furthermore, because saccades affect weak afterimages but not strong ones, we suggest that their effect is modulated by the ambiguity of the afterimage signal. © 2015 ARVO. Source

Kratzer I.,University of Lyon | Vasiljevic A.,University of Lyon | Vasiljevic A.,East Pathological Center | Rey C.,University of Lyon | And 4 more authors.
Histochemistry and Cell Biology | Year: 2012

The choroid plexus epithelium controls the movement of solutes between the blood and the cerebrospinal fluid. It has been considered as a functionally more immature interface during brain development than in adult. The anatomical basis of this barrier is the interepithelial choroidal junction whose tightness has been attributed to the presence of claudins. We used quantitative real-time polymerase chain reaction, Western blot and immunohistochemistry to identify different claudins in the choroid plexuses of developing and adult rats. Claudin-1, -2, and -3 were highly and selectively expressed in the choroid plexus as compared to brain or parenchyma microvessels and were localized at epithelial junctions. Claudin-6, -9, -19, and -22 also displayed a previously undescribed choroidal selectivity, while claudin-4, -5, and -16 were enriched in the cerebral microvessels. The choroidal pattern of tight junction protein expression in prenatal brains was already complex and included occludin and zonula occludens proteins. It differed from the adult pattern in that the poreforming claudin-2, claudin-9, and claudin-22 increased during development, while claudin-3 and claudin-6 decreased. Claudin-2 and claudin-11 presented a mirror image of abundance between lateral ventricle and fourth ventricle choroid plexuses. Imunohistochemical analysis of human fetal and postnatal brains for claudin-1, -2, and -3 demonstrated their early presence and localization at the apico-lateral border of the choroid plexus epithelial cells. Overall, choroidal epithelial tight junctions are already complex in developing brain. The observed differences in claudin expression between developing and adult choroid plexuses may indicate developmental differences in selective blood-cerebrospinal fluid transport functions. © Springer-Verlag 2012. Source

Strazielle N.,Lyon Neuroscience Research Center | Ghersi-Egea J.F.,French Institute of Health and Medical Research
Molecular Pharmaceutics | Year: 2013

The brain develops and functions within a strictly controlled environment resulting from the coordinated action of different cellular interfaces located between the blood and the extracellular fluids of the brain, which include the interstitial fluid and the cerebrospinal fluid (CSF). As a correlate, the delivery of pharmacologically active molecules and especially macromolecules to the brain is challenged by the barrier properties of these interfaces. Blood-brain interfaces comprise both the blood-brain barrier located at the endothelium of the brain microvessels and the blood-CSF barrier located at the epithelium of the choroid plexuses. Although both barriers develop extensive surface areas of exchange between the blood and the neuropil or the CSF, the molecular fluxes across these interfaces are tightly regulated. Cerebral microvessels acquire a barrier phenotype early during cerebral vasculogenesis under the influence of the Wnt/β-catenin pathway, and of recruited pericytes. Later in development, astrocytes also play a role in blood-brain barrier maintenance. The tight choroid plexus epithelium develops very early during embryogenesis. It is specified by various signaling molecules from the embryonic dorsal midline, such as bone morphogenic proteins, and grows under the influence of Sonic hedgehog protein. Tight junctions at each barrier comprise a distinctive set of claudins from the pore-forming and tightening categories that determine their respective paracellular barrier characteristics. Vesicular traffic is limited in the cerebral endothelium and abundant in the choroidal epithelium, yet without evidence of active fluid phase transcytosis. Inorganic ion transport is highly regulated across the barriers. Small organic compounds such as nutrients, micronutrients and hormones are transported into the brain by specific solute carriers. Other bioactive metabolites, lipophilic toxic xenobiotics or pharmacological agents are restrained from accumulating in the brain by several ATP-binding cassette efflux transporters, multispecific solute carriers, and detoxifying enzymes. These various molecular effectors differently distribute between the two barriers. Receptor-mediated endocytotic and transcytotic mechanisms are active in the barriers. They enable brain penetration of selected polypeptides and proteins, or inversely macromolecule efflux as it is the case for immnoglobulins G. An additional mechanism specific to the BCSFB mediates the transport of selected plasma proteins from blood into CSF in the developing brain. All these mechanisms could be explored and manipulated to improve macromolecule delivery to the brain. © 2013 American Chemical Society. Source

Schon D.,Aix - Marseille University | Schon D.,French Institute of Health and Medical Research | Tillmann B.,Lyon Neuroscience Research Center | Tillmann B.,University of Lyon
Annals of the New York Academy of Sciences | Year: 2015

This paper brings together different perspectives on the investigation and understanding of temporal processing and temporal expectations. We aim to bridge different temporal deficit hypotheses in dyslexia, dysphasia, or deafness in a larger framework, taking into account multiple nested temporal scales. We present data testing the hypothesis that temporal attention can be influenced by external rhythmic auditory stimulation (i.e., musical rhythm) and benefits subsequent language processing, including syntax processing and speech production. We also present data testing the hypothesis that phonological awareness can be influenced by several months of musical training and, more particularly, rhythmic training, which in turn improves reading skills. Together, our data support the hypothesis of a causal role of rhythm-based processing for language processing and acquisition. These results open new avenues for music-based remediation of language and hearing impairment. © 2015 New York Academy of Sciences. Source

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