No description available.

PURPOSE: To characterize the distribution of white matter neurons (WMNs) positive for perineuronal nets (PNNs) in the adult monkey. WMNs are a mixed population of excitatory and inhibitory neurons. They have an important role in axon guidance during cortical development, but their role in the adult brain is less understood. In vitro and in vivo experiments provide evidence that WMNs are incorporated into cortical circuitry. The majority of investigations in the adult, however, have focused on regional variations in overall density, or on characterization of morphological and neurochemical subtypes. The present study was motivated by the observation that some WMNs exhibit PNNs in adult monkey. Since PNNs are associated with plasticity in younger animals, their occurrence with some WMNs might be functionally significant. METHODS: PNNs were visualized, at the light microscopic level, by WFA staining in three adult macaque brains. Density of WFA positive WMNs was scored at three anterior-posterior levels (frontal, mid-hemispheric, and occipital), and compared with overall density of WMNs, as visualized by immunocytochemistry for NeuN. Quantitation of WFA+ neurons and neuron morphology were analyzed via light microscopy. Soma size and appearance, and dendritic length were recorded and measured. RESULTS: On the basis of soma size and proximal dendritic shape, several types of WFA+ WMNs were provisionally identified, consistent with previous reports in the literature. Subpopulation densities were of highest density in mid-cortical areas and lowest quantities at occipital, matching previous studies. Morphological measurements suggested a heterogeneous neuron population through soma measurements and dendrite orientation. Soma sizes exhibited a range of circularity and size (10 µm – 30 µm). Dendrites were stained beyond the “proximal” area, including intermediate areas beyond the first branch, and up to 500 µm. CONCLUSIONS: A small population of WMNs are coated by PNNs in adult monkey. On the basis of morphology, these might be further subdivided, but combined studies with other markers would be needed. Future studies might investigate age- or pathology-related changes in the density and subtypes of WMNs that express PNNs in human or nonhuman primates. We speculate that these WMNs might have functional specializations, perhaps similar to the plasticity effects documented for PNNs in early development.

No description available.

B virus is an alphaherpesvirus, endemic to macaque monkeys, capable of deadly human zoonosis with an 80% mortality rate in untreated cases. The macaque monkey is widely used in biomedical research and the threat of B virus poses an occupational hazard to researchers, veterinarians, and animal handlers. B virus establishes a life-long latent infection in sensory neurons of the peripheral nervous system (PNS) in the natural host. In human infections, B virus readily transits to the central nervous system (CNS) and destroys brain tissues. Identifying immune correlates of B virus infection in the PNS of the natural host is critical in understanding viral lethality in the human host. The lack of an accurate animal model and restrictions on handling potentially infected nervous tissue previously limited studies of B virus infection in macaque ganglia. To address this barrier, a long-lived mixed neuron/glia cell culture model was established from macaque DRG explants using a novel methodology that relied on cellular migration from whole tissues. Utilizing this model, the hypothesis tested was that acute B virus infection of macaque ganglia triggers cellular defense networks to promote leukocyte recruitment and impact leukocyte activation. Chemokines were upregulated in B virus-infected cultures and infected cell media induced leukocyte chemotaxis. Leukocytes were less effectively activated by media from infected cells when compared to media from mock-infected cells. To identify factors responsible for this, focused microarrays were performed and cytokine profiles were quantified from B virus and mock-infected culture supernatants. IL-6 protein levels were significantly reduced in B virus infected cultures. This observation led to the hypothesis that IL-6 downregulation impairs leukocyte activation and, indeed, when IL-6 was added to B virus-infected culture supernatants to control levels, these cultures were far more effective at eliciting leukocyte activation when compared with mock-infected cultures. Collectively, these data support the hypothesis that acute B virus infection of macaque ganglia triggers cellular defense networks to promote leukocyte recruitment and impact leukocyte activation and identifies a potential viral mechanism to impair leukocyte functionality. Additionally, this work presents a novel methodology for establishing long-lived mixed neuron/glia cultures from postnatal/adult macaque DRGs.

Le contexte temporel influence profondément la façon dont nous nous comportons. De manière similaire, il donne forme à l'activité du cortex moteur (LFP et potentiels d'action), pendant la préparation motrice, mais aussi en absence de préparation d'un mouvement. / The temporal context deeply shapes the motor cortical activity (spikes and LFPs), during movement preparation but also outside movement preparation.

No description available.

No description available.

Le cortex cérébral primate a subi des modifications majeures pendant l'évolution qui ont permis le développement de fonctions cognitives supérieures. Un accroissement massif a eu lieu avec l'extension spécifique des couches supragranulaires et une forte expansion tangentielle. Le cortex primate ne possède pas uniquement davantage de neurones, comparé au rongeur, mais aussi des différences qualitatives. Ceci suggère des différences qualitatives pendant le développement du cortex.Une zone proliférative corticale supplémentaire a été identifiée chez le singe macaque: la zone subventriculaire externe (OSVZ) supposée être impliquée dans l'expansion du cortex primate. Mais les propriétés des précurseurs de l'OSVZ restent mal connues. Des techniques de microscopie en temps réel et d'immunofluorescence ont permis de réaliser une description exhaustive des précurseurs de l'OSVZ et de leurs propriétés chez le singe macaque.Nos résultats mettent en évidence des différences primates/rongeurs majeures. Les observations en temps réel révèlent des capacités prolifératives bien plus importantes des précurseurs. Les précurseurs primates de l'OSVZ présentent des taux de prolifération variables pendant la corticogenèse liés à la cinétique du cycle cellulaire. Nos enregistrements ont permis la génération d'une grande base de données de propriétés et lignages de précurseurs et la mise en évidence d’une diversité morphologique inattendue. 5 types ont été identifiés. Impliqués dans des lignages complexes, chaque type a la capacité de s'auto-renouveler et de générer directement des neurones. Parallèlement, nous avons développé une méthode de classification non supervisée des précurseurs corticaux. Cette technique a identifié les mêmes 5 types de précurseurs.Les résultats de cette thèse apportent de nouveaux éléments dans la compréhension des spécificités de la corticogenèse primate qui contribuent à l'expansion corticale et au développement de capacités cognitives supérieures. / The primate cerebral cortex underwent major modifications during evolution that enabled the development of high cognitive functions. A massive enlargement occurred with the specific expansion of the supra granular layers and the apparition of new frontal areas. Not only quantitative differences are found compared to the rodent but also qualitative differences. This points to potential qualitative differences in primate cortical development. An extra proliferating zone had already been identified during macaque corticogenesis: the outer subventricular zone (OSVZ). This zone is assumed to play a key role in the expansion of the primate cortex but the cellular and functional properties of OSVZ precursors remain elusive. We used quantitative long-term time-lapse video-microscopy (TLV) and immunofluorescence in and ex vivo to perform a detailed and exhaustive description of OSVZ precursor types and proliferative abilities at different stages of macaque cortical development. Our results highlight major rodent/primate differences. TLV observations revealed a much higher proliferative potential of OSVZ compared to the rodent SVZ. We report variable rates of proliferation linked to cell-cycle duration in a stage-specific manner. TLV recordings allowed the formation of a large database of primate precursor properties and lineages. This dataset unravelled an unexpectedly high diversity of OSVZ precursor morphologies. Five precursor types were identified. Involved in complex lineages, each precursor type can self-renew and directly generate neurons. In a parallel approach, we developed an unbiased clustering tool to automatically classify cortical precursors. This technique returned the same five precursor types as the morphological categorization. The results of this PhD thesis provide new insights into primate specificities during corticogenesis that contribute to cortical expansion and to the development of higher cognitive abilities.