The human brain is subdivided into distinct anatomical structures, including the neocortex, which in turn encompasses dozens of distinct specialized cortical areas. Early morphogenetic gradients are known to establish early brain regions and cortical areas, but how early patterns result in finer and more discrete spatial differences remains poorly understood1. Here we use single-cell RNA sequencing to profile ten major brain structures and six neocortical areas during peak neurogenesis and early gliogenesis. Within the neocortex, we find that early in the second trimester, a large number of genes are differentially expressed across distinct cortical areas in all cell types, including radial glia, the neural progenitors of the cortex. However, the abundance of areal transcriptomic signatures increases as radial glia differentiate into intermediate progenitor cells and ultimately give rise to excitatory neurons. Using an automated, multiplexed single-molecule fluorescent in situ hybridization approach, we find that laminar gene-expression patterns are highly dynamic across cortical regions. Together, our data suggest that early cortical areal patterning is defined by strong, mutually exclusive frontal and occipital gene-expression signatures, with resulting gradients giving rise to the specification of areas between these two poles throughout successive developmental timepoints.

Neural tracing studies have revealed that the rat medial and lateral septum are targeted by ascending projections from the nucleus incertus, a population of tegmental GABA neurons. These neurons express the relaxin‐family peptide, relaxin‐3, and pharmacological modulation of relaxin‐3 receptors in medial septum alters hippocampal theta rhythm and spatial memory. In an effort to better understand the basis of these interactions, we have characterized the distribution of relaxin‐3 fibers/terminals in relation to different septal neuron populations identified using established protein markers. Dense relaxin‐3 fiber plexuses were observed in regions of medial septum containing hippocampal‐projecting choline acetyltransferase (ChAT)‐, neuronal nitric oxide synthase (nNOS)‐, and parvalbumin (PV)‐positive neurons. In lateral septum (LS), relaxin‐3 fibers were concentrated in the ventrolateral nucleus of rostral LS and the ventral nucleus of caudal LS, with sparse labeling in the dorsolateral and medial nuclei of rostral LS, dorsal nucleus of caudal LS, and ventral portion nuclei. Relaxin‐3 fibers were also observed in the septofimbrial and triangular septal nuclei. In the medial septum, we observed relaxin‐3‐immunoreactive contacts with ChAT‐, PV‐, and glutamate decarboxylase‐67‐positive neurons that projected to hippocampus, and contacts between relaxin‐3 terminals and calbindin‐ and calretinin‐positive neurons. Relaxin‐3 colocalized with synaptophysin in nerve terminals in all septal areas, and ultrastructural analysis revealed these terminals were symmetrical and contacted spines, somata, dendritic shafts, and occasionally other axonal terminals. These data predict that this GABA/peptidergic projection modulates septohippocampal activity and hippocampal theta rhythm related to exploratory navigation, defensive and ingestive behaviors, and responses to neurogenic stressors. J. Comp. Neurol. 520:1903–1939, 2012. © 2011 Wiley Periodicals, Inc.

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Registro de acceso restringido Este recurso no está disponible en acceso abierto por política de la editorial. No obstante, se puede acceder al texto completo desde la Universitat Jaume I o si el usuario cuenta con suscripción. Registre d'accés restringit Aquest recurs no està disponible en accés obert per política de l'editorial. No obstant això, es pot accedir al text complet des de la Universitat Jaume I o si l'usuari compta amb subscripció. Restricted access item This item isn't open access because of publisher's policy. The full--text version is only available from Jaume I University or if the user has a running suscription to the publisher's contents.

The human brain is subdivided into distinct anatomical structures. The neocortex, one of these structures, enables higher-order sensory, associative, and cognitive functions, and in turn encompasses dozens of distinct specialized cortical areas. Early morphogenetic gradients are known to establish an early blueprint for the specification of brain regions and cortical areas. Furthermore, recent studies have uncovered distinct transcriptomic signatures between opposing poles of the developing neocortex1. However, how early, broad developmental patterns result in finer and more discrete spatial differences across the adult human brain remains poorly understood2. Here, we use single-cell RNA-sequencing to profile ten major brain structures and six neocortical areas during peak neurogenesis and early gliogenesis. Our data reveal that distinct cell subtypes are predominantly brain-structure specific. Within the neocortex, we find that even early in the second trimester, a large number of genes are differentially expressed across distinct cortical areas in all cell types, including radial glia, the neural progenitors of the cortex. However, the abundance of areal transcriptomic signatures increases as radial glia differentiate into intermediate progenitor cells and ultimately give rise to excitatory neurons. Using an automated, multiplexed single-molecule fluorescent in situ hybridization (smFISH) approach, we validated the expression pattern of area-specific neuronal genes and also discover that laminar gene expression patterns are highly dynamic across cortical regions. Together, our data suggest that early cortical areal patterning is defined by strong, mutually exclusive frontal and occipital gene expression signatures, with resulting gradients giving rise to the specification of areas between these two poles throughout successive developmental timepoints.

Aggregation of hyperphosphorylated tau in neurofibrillary tangles (NFTs) is closely associated with neuronal death and cognitive decline in Alzheimer's disease (AD). To define the signatures that distinguish between aggregation-prone and resistant cell states in AD, we developed a FACS-based method for the high-throughput isolation and transcriptome profiling of individual cells with cytoplasmic aggregates and profiled 63,110 somas from human AD brains. By comparing NFTbearing and NFT-free somas within and across neuronal subtypes, we identified the cell-type-specific and shared states. NFT-bearing neurons shared a marked upregulation of genes associated with synaptic transmission, including a core set of 63 genes enriched for synaptic vesicle cycle and transsynaptic signaling, whereas glucose metabolism and oxidative phosphorylation changes were highly neuronal-subtype-specific. Apoptosis was modestly enriched in NFT-bearing neurons despite the strong link between tau and cell death. Our datasets provide a resource for investigating taumediated neurodegeneration and a platform for biomarker and drug target discovery.

Registro de acceso restringido Este recurso no está disponible en acceso abierto por política de la editorial. No obstante, se puede acceder al texto completo desde la Universitat Jaume I o si el usuario cuenta con suscripción. Registre d'accés restringit Aquest recurs no està disponible en accés obert per política de l'editorial. No obstant això, es pot accedir al text complet des de la Universitat Jaume I o si l'usuari compta amb subscripció. Restricted access item This item isn't open access because of publisher's policy. The full--text version is only available from Jaume I University or if the user has a running suscription to the publisher's contents.