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Two geophysical expeditions (LOMROG II and III) were carried out in 2009 and 2012 to acquire seismic data in the western Amundsen Basin in the Arctic Ocean, a basin formed by ultraslow seafloor spreading at the Gakkel Ridge. Previous studies show alternating magmatic and amagmatic segments at the ridge but it is unclear if such segmentation persisted throughout the entire opening history of the basin. The seismic refraction data were used to develop P -wave velocity models down to the uppermost mantle using forward modelling of traveltimes. The coincident seismic reflection data were used to constrain the geometry of the sedimentary layers and for characterizing the acoustic basement. 2-D gravity modelling was used to determine the Moho depth in areas when data quality was insufficient to resolve a Moho reflection. The models distinguish three different basement types: oceanic crust with layers 2 and 3, oceanic crust that is lacking a layer 3 and exhumed and serpentinized mantle. The maximum observed crustal thickness is 6 km. Areas with thin crust (<3 km) may be underlain by partially serpentinized mantle. Where exhumed mantle is observed, a serpentinization front separates highly serpentinized mantle at the top from partially serpentinized mantle below. The presence of oceanic crust off-axis of the presently amagmatic sector of the Gakkel Ridge indicates that there is both a spatial and temporal variation of crustal accretion processes at the ridge. [ABSTRACT FROM AUTHOR]

This study examines the velocity structure of Makarov Basin and the adjacent Alpha Ridge to determine the tectonic origins of these features and link them to the larger Amerasia Basin. Seismic data from sonobuoys distributed along a 650 km-long line extending from Alpha Ridge and across Makarov Basin to the Lomonosov Ridge were analyzed for this purpose. Forward modelling of traveltimes, supported by coincident multi-channel seismic reflection and shipborne gravity data, were used to determine the P-wave velocity structure along the line. The sedimentary cover averages 0.5 km-thick on Alpha Ridge and 1.9 km-thick in Makarov Basin, but reaches up to 5 km-thick at the base of Lomonosov Ridge. Velocities in the sedimentary section range from 1.6 to 4.3 km s − 1 . As suggested by relatively high velocities, interbedded volcaniclastic or volcanic rock may occur in the deep sedimentary section. The shallow basement of Alpha Ridge (3.3 to 3.6 km s − 1 ) is characterized by semi-continuous high amplitude reflections and is interpreted as volcanic rock possibly intercalated with sedimentary rock. Velocities do not vary significantly in the upper and mid-crustal layers between Alpha Ridge and Makarov Basin. Total crustal thickness decreases from 27 km beneath Alpha Ridge to 5 km-thick in Makarov Basin then thickens to > 20 km over a short distance as part of Lomonosov Ridge. The crustal structure of Alpha Ridge is consistent with previous studies suggesting that the Alpha-Mendeleev ridge complex is part of a large igneous province (LIP) with thick igneous crust. The lack of change in crustal velocities between Alpha Ridge and Makarov Basin suggests that the basin, at least partly, either formed during or was influenced by LIP-related magmatism. The rapid transition of crustal thicknesses from Makarov Basin to Lomonosov Ridge supports the interpretation that this section of the ridge is a transform margin. [ABSTRACT FROM AUTHOR]

The peri-infarct cortex (PIC) is the site of long-term physiologic changes after ischemic stroke. Traditional methods for delineating the peri-infarct gray matter (GM) have used a volumetric Euclidean distance metric to define its extent around the infarct. This metric has limitations in the case of cortical stroke, i.e., those where ischemia leads to infarction in the cortical GM, because the vascularization of the cerebral cortex follows the complex, folded topology of the cortical surface. Instead, we used a geodesic distance metric along the cortical surface to subdivide the PIC into equidistant rings emanating from the infarct border and compared this new approach to a Euclidean distance metric definition. This was done in 11 patients with [F-18]-Flumazenil ([18-F]-FMZ) positron emission tomography (PET) scans at 2 weeks post-stroke and at 6 month follow-up. FMZ is a PET radiotracer with specific binding to the alpha subunits of the type A γ-aminobutyric acid (GABAA) receptor. Additionally, we used partial-volume correction (PVC) of the PET images to compensate for potential cortical thinning and long-term neuronal loss in follow-up images. The difference in non-displaceable binding potential (BPND) between the stroke unaffected and affected hemispheres was 35% larger in the geodesic versus the Euclidean peri-infarct models in initial PET images and 48% larger in follow-up PET images. The inter-hemispheric BPND difference was approximately 17-20% larger after PVC when compared to uncorrected PET images. PET studies of peri-infarct GM in cortical strokes should use a geodesic model and include PVC as a preprocessing step. Hum Brain Mapp 38:326-338, 2017. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

During expedition PS115/1, the German research vessel Polarstern acquired seismic refraction data along a 102-km-long profile crossing Greenland's northern continental margin and extending up to the southwestern limit of the Morris Jesup Spur. A P–wave velocity model is obtained and validated by gravity modelling. A nearby seismic reflection line provides insights on the structures within the sedimentary cover. Beneath a 2-km-thick sedimentary cover with velocities of 1.8 km/s to 3.4 km/s, an up to 1.5-km-thick layer is characterized by velocities of 4.2 km/s and is interpreted to consist of volcanic rocks. This is consistent with proposed volcanic activity on the Morris Jesup Spur and exposed volcano-sedimentary rocks of the nearby Kap Washington Group. Below the volcanic rocks, an up to 7 km-thick unit with velocities of 4.4 to 5.8 km/s is interpreted to consist of metasedimentary rocks still belonging to the deformed units of the Franklinian Basin. The seismic reflection data image a tectonic overprint of the acoustic basement and the lowermost sedimentary layers. Tectonic faults indicating the tectonic overprint do not reach to the uppermost sedimentary layers. This hints at an older fracture zone that is also observed in the velocity model and aligns well with observed anomalies in the regional gravity and magnetic fields. The seismic velocity model reveals a highly extended continental crust that shows a magmatic overprint at all crustal levels. The upper crust is 5 km thick with a velocity of 6.0 km/s. However, in three distinct zones its thickness is up to 8 km and the velocity increases to 6.3 km/s. These zones are interpreted as magmatic intrusions into the upper crust. The lower crust represents a 9-km-thick high-velocity layer (7.2 km/s) that is interpreted as magmatic underplating or lower crustal sill intrusions. Such a high-velocity lower crust is not present in models of adjacent Arctic margins. PACS: 0000, 1111 2000 MSC: 0000, 1111 [Display omitted] • Deformed Franklinian Basin, thus Laurentia extends northward beyond North Greenland. • Shipborne geophysical data show upper crustal intrusions and a high-velocity lower crust beneath the margin. • Volcanic units are interbedded into the sedimentary cover. • NW-SE striking fault zone separates Morris Jesup Spur and North Greenland. [ABSTRACT FROM AUTHOR]

Tissue radioactivity concentrations, measured with positron emission tomography (PET) are subject to partial volume effects (PVE) due to the limited spatial resolution of the scanner. Last generation high-resolution PET cameras with a full width at half maximum (FWHM) of 2–4 mm are less prone to PVEs than previous generations. Corrections for PVEs are still necessary, especially when studying small brain stem nuclei or small variations in cortical neuroreceptor concentrations which may be related to cytoarchitectonic differences. Although several partial-volume correction (PVC) algorithms exist, these are frequently based on a priori assumptions about tracer distribution or only yield corrected values of regional activity concentrations without providing PVE corrected images. We developed a new iterative deconvolution algorithm (idSURF) for PVC of PET images that aims to overcome these limitations by using two innovative techniques: 1) the incorporation of anatomic information from a cortical gray matter surface representation, extracted from magnetic resonance imaging (MRI) and 2) the use of anatomically constrained filtering to attenuate noise. PVE corrected images were generated with idSURF implemented into a non-interactive processing pipeline. idSURF was validated using simulated and clinical PET data sets and compared to a frequently used standard PVC method (Geometric Transfer Matrix: GTM). The results on simulated data sets show that idSURF consistently recovers accurate radiotracer concentrations within 1–5% of true values. Both radiotracer concentrations and non-displaceable binding potential (BPnd) values derived from clinical PET data sets with idSURF were highly correlated with those obtained with the standard PVC method (R 2 = 0.99, error = 0%–3.2%). These results suggest that idSURF is a valid and potentially clinically useful PVC method for automatic processing of large numbers of PET data sets. [ABSTRACT FROM AUTHOR]

The crustal structure in the southern Davis Strait and the adjacent ocean–continent transition zone in NE Labrador Sea was determined along a 185-km-long refraction/wide-angle reflection seismic transect to study the impact of the Iceland mantle plume to this region. A P-wave velocity model was developed from forward and inverse modelling of dense airgun shots recorded by ocean bottom seismographs. A coincident industry multichannel reflection seismic profile was used to guide the modelling as reflectivity could be identified down to Moho. The model displays a marked lateral change of velocity structure. The sedimentary cover (velocities 1.8–3.9 km s−1) is up to 4 km thick in the north and thins to 1 km in the south. The segment of the line within southern Davis Strait is interpreted to be of continental character with a two-layered 13-km-thick crust with P-wave velocities of 5.6–5.8 and 6.4–6.7 km s−1 in the upper and lower crust, respectively. The crust is underlain by a 2- to 4-km-thick high-velocity layer (7.5 km s−1). This layer we interpret as underplated material related to the Iceland plume. The southern segment of the line in Labrador Sea displays a 2-km-thick layer with a velocity of 4.5 km s−1. This layer can be correlated to a well about 100 km to the west of the line, where Palaeocene basalts and interbedded sediments were drilled. Underneath is a 12-km-thick crust with a 2-km-thick upper layer (5.8–6.6 km s−1) and a 10-km-thick lower layer (6.8–7.2 km s−1). This crust is interpreted to be of oceanic character. S-wave modelling yields a Poisson's ratio of 0.28 for the lower crust, compatible with a gabbroic composition. The igneous crust is 5 km thicker than normal oceanic crust. We suggest that the increased magma production was created by buoyancy-driving flow. We propose a model in which initial seafloor spreading occurred between Labrador and West Greenland, when the Iceland plume arrived in the area at ∼62 Ma and caused enhanced magma production. Shortly afterwards (chron 27–26), plume material was channelled southward underplating part of Davis Strait and forming basaltic flows interbedded with sediment. [ABSTRACT FROM AUTHOR]

Seismic reflection and refraction data were acquired along the southeast margin of Flemish Cap at a position conjugate to drilling and geophysical surveys across the Galicia Bank margin. The data document first-order asymmetry during final break-up between Newfoundland and Iberia. An abrupt necking profile of continental crust observed off Flemish Cap contrasts strongly with gradual tapering on the conjugate margin. There is no evidence beneath Flemish Cap for a final phase of continental extension that resulted in thin continental crust underlain by a strong ‘S’-like reflection, which indicates that this mode of extension occurred only on the Galicia Bank margin. Compelling evidence for a broad zone of exhumed mantle or for peridotite ridges is also lacking along the Flemish Cap margin. Instead, anomalously thin, 3–4-km-thick oceanic crust is observed. This crust is highly tectonized and broken up by high-angle normal faulting. The thin crust and rift structures that resemble the abandoned spreading centre in the Labrador sea suggest that initial seafloor spreading was affected by processes observed in present-day ultra-slow spreading environments. Landwards, Flemish Cap is underlain by a highly reflective lower crust. The reflectivity most likely originates from older Palaeozoic orogenic structures that are unrelated to extension and break-up tectonics. [ABSTRACT FROM AUTHOR]

Prestack depth-migrated seismic reflection data collected off Flemish Cap on the Newfoundland margin show a structure of abruptly thinning continental crust that leads into an oceanic accretion system. Within continental crust, there is no clear evidence for detachment surfaces analogous to the S reflection off the conjugate Galicia Bank margin, demonstrating a first-order asymmetry in final rift development. Anomalously thin (3-4 km), magmatically produced oceanic crust abuts very thin continental crust and is highly tectonized. This indicates that initial accretion of the oceanic crust was in a magma-limited setting similar to presentday ultraslow spreading environments. Seaward, oceanic crust thins to <1.3 km and exhibits an unusual, highly reflective layering. We propose that a period of magma starvation led to exhumation of mantle in an oceanic core complex that was subsequently buried by deep-marine sheet flows to form this layering. Subsequent seafloor spreading formed normal, ∼6-km-thick oceanic crust. This interpretation implies large fluctuations in the available melt supply during the early stages of seafloor spreading before a more typical slow-spreading system was established. Keywords: continental margin; seafloor spreading; extension tectonics; continental breakup. [ABSTRACT FROM AUTHOR]

The crustal structure of the eastern Grenville and Makkovik provinces was determined using two onshore–offshore refraction seismic lines of the Lithoprobe Eastern Canadian Shield Onshore–Offshore Transect (ECSOOT). A gravity high in the Hawke River terrane correlates with increased P-wave velocities in the upper 30 km of the crust (6.2–6.7 km/s in the upper and middle crust and 6.9–7.1 km/s below) which we interpret as structure inherited from the Labradorian orogen. Velocities in the adjacent Groswater Bay terrane are 6.0–6.55 km/s in the upper and middle crust and 6.6–6.95 km/s in the lower crust. The entire Grenville crust is underlain by a 15–20 km thick high-velocity lower crustal (HVLC) wedge consisting of an upper layer (7.1–7.4 km/s) and a lower layer (7.6–7.8 km/s). The HVLC wedge is interpreted as an underplated layer formed during Iapetan rifting. This interpretation is based on the correlation with the 615 Ma Long Range dykes onshore and the eastward termination of the wedge at the Cartwright Arch. Similar HVLC layers are found offshore western Newfoundland, suggesting that the underplating may be a continuous feature along the passive Grenvillian margin. The Cartwright Arch is characterized by velocities of 6.4 km/s and 4 km thick sediment sequences (4.3–5.7 km/s) in the surrounding basin, interpreted as an extensional basin with basaltic magmatism within the arch. The Grenville front is clearly marked by a decrease of velocities in the Makkovik Province (5.8–6.4 km/s in the upper and middle crust, 6.65–6.85 km/s in the lower crust) and a gradual thickening of the crust (not including the HVLC layer) from 30 km in the Grenville Province to 35 km in the Makkovik Province.La structure crustale de l'est des provinces de Grenville et de Makkovik a été déterminée en utilisant les données de deux lignes de réfraction sismique du transect Lithoprobe des zones continentales et extracôtières de la partie l'est du Bouclier canadien (ECSOOT, Eastern Canadian Shield Onshore-Offshore Transect). Un maximum gravimétrique dans le terrane de la rivière Hawke concorde avec des augmentations des vitesses de l'onde P dans les 30 km supérieurs de la croûte (6,2–6,7 km/s dans la croûte supérieure et médiane et 6,9–7,1 km/s pour la croûte inférieure) ce que nous interprétons comme une structure héritée de l'orogène labradorien. Les vitesses dans le terrane adjacent de Groswater Bay sont de 6,0–6,55 km/s dans la croûte supérieure et médiane et de 6,6–6,95 km/s dans la croûte inférieure. La croûte du Grenville au complet recouvre un coin de haute vitesse de la croûte inférieure (HVLC) de 15 à 20 km d'épaisseur, lequel comprend une couche supérieure (7,1–7,4 km/s) et une couche inférieure (7,6–7,8 km/s). Ce coin HVLC est interprété comme une couche infraplaque formée au cours de la dérive de l'Iapetus. Cette interprétation est basée sur une corrélation avec les dykes Long Range (615 Ma) sur la côte et l'extrémité est du coin à l'arche Cartwright. Des couches HVLC semblables se retrouvent au large de l'ouest de Terre-Neuve, suggérant que le sous-placage peut être une caractéristique continue le long de la marge passive du Grenville. L'arche Cartwright est caractérisée par des vitesses de 6,4 km/s et les séquences sédimentaires du bassin environnant (4,3–5,7 km/s et 4 km d'épaisseur) sont interprétées comme un bassin d'extension avec du magmatisme basaltique à l'intérieur de l'arche. Le front du Grenville est nettement défini par une diminution des vitesses dans la province de Makkovik (5,8–6,4 km/s pour la croûte supérieure et médiane et 6,65–6,85 km/s pour la croûte inférieure) ainsi qu'un épaississement graduel de la croûte (n'incluant pas la couche HVLC) de 30 km dans le Grenville à 35 km dans la province de Makkovik.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Two wide-angle seismic reflection/refraction profiles were acquired to determine the velocity characteristics of the Meguma terrane and adjacent Avalonia northeast of the Cobequid-Chedabucto Fault Zone (CCFZ) in eastern Canada. Line 99–1 is located along the Scotian margin whereas line 99–2 crosses the Scotian margin and onshore Nova Scotia and extends into the Gulf of St. Lawrence. Velocity models were derived by forward modelling of travel times. P-wave velocities of 5.5–6.0 km/s and 6.0–6.4 km/s are interpreted to be metasedimentary rocks of the Goldenville and Halifax groups and granitic rocks, respectively. This inference is based on comparison with laboratory velocities of a suite of rock samples, offshore sampling, links to onshore geology with multibeam bathymetry, and gravity modelling. On both lines a low velocity zone (LVZ) >350 km wide and up to 15 km thick is present at mid-crustal levels. The LVZ is not observed beneath onshore Nova Scotia or northeast of Orpheus Graben, the offshore extension of the CCFZ. The crustal thickness of the Meguma terrane varies between 31 and 38 km; in contrast, the Moho is at a depth of 41 km beneath Avalonia. The velocity of the lower crust on line 99–2 is 6.8–7.1 km/s beneath the LVZ and Avalonia, and 6.6 km/s beneath onshore Meguma terrane. Poisson's ratios calculated from P- and S-wave velocities are 0.19–0.23 in the Meguma terrane crust; in contrast, Poisson's ratios of 0.24–0.25 are indicated for Avalonian crust. • Seismic reflection/refraction, gravity, and rock density/velocity data were obtained. • Two velocity/depth models were generated onshore and offshore of Nova Scotia, Canada. • Both models show an extensive low-velocity zone in the offshore Meguma terrane. • Meguma terrane has crustal structure different from that of adjacent Avalonia. • Avalonia extends only 30 km under Meguma terrane in faulted contact. [ABSTRACT FROM AUTHOR]

Orphan Basin, a massive deepwater rifted basin off the northeastern coast of Newfoundland, was one of the targets of the 2009 SIGNAL (Seismic Investigations off Greenland, Newfoundland and Labrador) experiment to collect refraction/wide-angle reflection (RWAR) data from the Bonavista Platform, through the Orphan Basin, to the Orphan Knoll, and beyond into oceanic crust. Both the data from an earlier RWAR acquisition and the new data were jointly analysed in order to improve on the earlier velocity model and extend its coverage landward and seaward. The resulting velocity model is characterized by an 8–9-km-thick sedimentary package immediately outboard of the Bonavista Platform, which thins toward the Orphan Knoll and beyond. The shallowest modelled sedimentary layer, interpreted as Paleocene and younger post-rift sediments, does not show significant thickness variations and velocities do not exceed 3.3 km s–1. The second modelled sedimentary layer with laterally variable velocities ranging from 2.3 to 5.3 km s–1, interpreted as Late Cretaceous post-rift sediments, is thickest over an interpreted failed rift. The deepest modelled sedimentary layer consists of laterally variable velocities that do not exceed 5.9 km s–1 and is interpreted as possibly Jurassic to Early Cretaceous syn-rift sediments. The crust beneath the Bonavista Platform is subdivided into an upper (5.4–5.9 km s–1), middle (5.9–6.4 km s–1) and lower crust (6.4–6.9 km s–1). The middle crust is modelled as disappearing beneath the seaward limit of the Bonavista Platform at an interpreted failed rift, only to re-appear 100 km further seaward beneath the central Orphan Basin and extend to the seaward limit of the Orphan Knoll, beyond which the crust can be modelled by just an upper (5.0–6.7 km s–1) and a lower (6.7–7.0 km s–1) crustal layer. Towards land, for the first 450 km of the model, velocities generally follow the globally averaged velocity trend for rifted continental crust, albeit with slightly elevated velocities suggestive of magmatic contributions. At the failed rift, within the continental domain, hyperextended crust is modelled, overlying a limited zone of serpentinized mantle. Seaward of Orphan Knoll, the interpretation for the velocity structure is less definitive but an 80-km-wide continent–ocean transition zone consisting of either transitional embryonic oceanic crust or thinned continental crust overlying serpentinized mantle is proposed. Upper mantle velocities as low as 7.7 km s–1 are modelled beneath the interpreted failed continental rift as well as beneath the continent–ocean transition zone, while the rest of the crustal model is underlain by typical mantle velocities of 8 km s–1. Analysis of extension and thinning factors based on the velocity model reveal that the failed rift experienced hyperextension and should have achieved full crustal embrittlement, consistent with localized mantle serpentinization. [ABSTRACT FROM AUTHOR]

An imbalance between excitatory and inhibitory neurotransmission has been linked to fibromyalgia (FM). Magnetic resonance spectroscopy has shown increased levels of glutamate in the insula and posterior cingulate cortex in FM as well as reduced insular levels of gamma-aminobutyric acid (GABA). Both of these changes have been associated with increased pain sensitivity. However, it is not clear whether excitatory and/or inhibitory neurotransmission is altered across the brain. Therefore, the aim of this study was to quantify GABAA receptor concentration on the whole brain level in FM to investigate a potential dysregulation of the GABAergic system. Fifty-one postmenopausal women (26 FM, 25 matched controls) underwent assessments of pain sensitivity, attention and memory, psychological status and function, as well as positron emission tomography imaging using a tracer for GABAA receptors, [F]flumazenil. Patients showed increased pain sensitivity, impaired immediate memory, and increased cortical GABAA receptor concentration in the attention and default-mode networks. No decrease of GABAA receptor concentration was observed. Across the 2 groups, GABAA receptor concentration correlated positively with functional scores and current pain in areas overlapping with regions of increased GABAA receptor concentration. This study shows increased GABAA receptor concentration in FM, associated with pain symptoms and impaired function. The changes were widespread and not restricted to pain-processing regions. These findings suggest that the GABAergic system is altered, possibly indicating an imbalance between excitatory and inhibitory neurotransmission. Future studies should try to understand the nature of the dysregulation of the GABAergic system in FM and in other pain syndromes. [ABSTRACT FROM AUTHOR]

Based on quantitative cyto- and receptor architectonic analyses, we identified 35 prefrontal areas, including novel subdivisions of Walker's areas 10, 9, 8B, and 46. Statistical analysis of receptor densities revealed regional differences in lateral and ventrolateral prefrontal cortex. Indeed, structural and functional organization of subdivisions encompassing areas 46 and 12 demonstrated significant differences in the interareal levels of α2 receptors. Furthermore, multivariate analysis included receptor fingerprints of previously identified 16 motor areas in the same macaque brains and revealed 5 clusters encompassing frontal lobe areas. We used the MRI datasets from the non-human primate data sharing consortium PRIME-DE to perform functional connectivity analyses using the resulting frontal maps as seed regions. In general, rostrally located frontal areas were characterized by bigger fingerprints, that is, higher receptor densities, and stronger regional interconnections. Whereas more caudal areas had smaller fingerprints, but showed a widespread connectivity pattern with distant cortical regions. Taken together, this study provides a comprehensive insight into the molecular structure underlying the functional organization of the cortex and, thus, reconcile the discrepancies between the structural and functional hierarchical organization of the primate frontal lobe. Finally, our data are publicly available via the EBRAINS and BALSA repositories for the entire scientific community. [ABSTRACT FROM AUTHOR]

The somatosensory cortex is a brain region responsible for receiving and processing sensory information from across the body and is structurally and functionally heterogeneous. Since the chemoarchitectonic segregation of the cerebral cortex can be revealed by transmitter receptor distribution patterns, by using a quantitative multireceptor architectonical analysis, we determined the number and extent of distinct areas of the macaque somatosensory cortex. We identified three architectonically distinct cortical entities within the primary somatosensory cortex (i.e., 3bm, 3bli, 3ble), four within the anterior parietal cortex (i.e., 3am, 3al, 1 and 2) and six subdivisions (i.e., S2l, S2m, PVl, PVm, PRl and PRm) within the lateral fissure. We provide an ultra-high resolution 3D atlas of macaque somatosensory areas in stereotaxic space, which integrates cyto- and receptor architectonic features of identified areas. Multivariate analyses of the receptor fingerprints revealed four clusters of identified areas based on the degree of (dis)similarity of their receptor architecture. Each of these clusters can be associated with distinct levels of somatosensory processing, further demonstrating that the functional segregation of cortical areas is underpinned by differences in their molecular organization. • Cyto-, myelo- and receptor-based mapping of macaque somatosensory cortex. • Medial-lateral segregation exists in the receptor architectures of areas 3a and 3b. • Novel subdivisions were identified within the macaque SII complex. • Cluster analysis unveiled the hierarchical processing within somatosensory cortex. [ABSTRACT FROM AUTHOR]

The article discusses a study that summarises the status of the Continental Shelf Project of the Kingdom of Denmark after the submission for an extended continental shelf in the area to the north of Greenland. Topics mentioned include the 1982 United Nations Convention on the Law of the Sea, the five partial submissions of the Kingdom of Denmark, and documentation of the sediment thickness in the Northern Deep through modern seismic reflection data.

Existing cytoarchitectonic maps of the human and macaque posterior occipital cortex differ in the number of areas they display, thus hampering identification of homolog structures. We applied quantitative in vitro receptor autoradiography to characterize the receptor architecture of the primary visual and early extrastriate cortex in macaque and human brains, using previously published cytoarchitectonic criteria as starting point of our analysis. We identified 8 receptor architectonically distinct areas in the macaque brain (mV1d, mV1v, mV2d, mV2v, mV3d, mV3v, mV3A, mV4v), and their respective counterpart areas in the human brain (hV1d, hV1v, hV2d, hV2v, hV3d, hV3v, hV3A, hV4v). Mean densities of 14 neurotransmitter receptors were quantified in each area, and ensuing receptor fingerprints used for multivariate analyses. The 1st principal component segregated macaque and human early visual areas differ. However, the 2nd principal component showed that within each species, area-specific differences in receptor fingerprints were associated with the hierarchical processing level of each area. Subdivisions of V2 and V3 were found to cluster together in both species and were segregated from subdivisions of V1 and from V4v. Thus, comparative studies like this provide valuable architectonic insights into how differences in underlying microstructure impact evolutionary changes in functional processing of the primate brain and, at the same time, provide strong arguments for use of macaque monkey brain as a suitable animal model for translational studies. [ABSTRACT FROM AUTHOR]

The Davis Strait is located between Canada and Greenland and connects the Labrador Sea and the Baffin Bay basins. Both basins formed in Cretaceous to Eocene time and were connected by a transform fault system in the Davis Strait. Whether the crust in the central Davis Strait is oceanic or continental has been disputed. This information is needed to understand the evolution of this transform margin during the separation of the North American plate and Greenland. We here present a 315-km-long east–west-oriented profile that crosses the Davis Strait and two major transform fault systems—the Ungava Fault Complex and the Hudson Fracture Zone. By forward modelling of data from 12 ocean bottom seismographs, we develop a P-wave velocity model. We compare this model with a density model from ship-borne gravity data. Seismic reflection and magnetic anomaly data support and complement the interpretation. Most of the crust is covered by basalt flows that indicate extensive volcanism in the Davis Strait. While the upper crust is uniform, the middle and lower crust are characterized by higher P-wave velocities and densities at the location of the Ungava Fault Complex. Here, P-wave velocities of the middle crust are 6.6 km s−1 and of the lower crust are 7.1 km s−1 compared to 6.3 and 6.8 km s−1 outside this area; densities are 2850 and 3050 kg m−3 compared to 2800 and 2900 kg m−3. We here interpret a 45-km-long section as stretched and intruded crust or as new igneous crust that correlates with oceanic crust in the southern Davis Strait. A high-velocity lower crust (6.9–7.3 km s−1) indicates a high content of mafic material. This mantle-derived material gradually intruded the lower crust of the adjacent continental crust and can be related to the Iceland mantle plume. With plate kinematic modelling, we can demonstrate the importance of two transform fault systems in the Davis Strait: the Ungava Fault Complex with transpression and the Hudson Fracture Zone with pure strike-slip motion. We show that with recent poles of rotation, most of the relative motion between the North American plate and Greenland took place along the Hudson Fracture Zone. [ABSTRACT FROM AUTHOR]

SUMMARY Baffin Bay represents the northern extension of the extinct rift system in the Labrador Sea. While the extent of oceanic crust and magnetic spreading anomalies are well constrained in the Labrador Sea, no magnetic spreading anomalies have yet been identified in Baffin Bay. Thus, the nature and evolution of the Baffin Bay crust remain uncertain. To clearly characterize the crust in southern Baffin Bay, 42 ocean bottom seismographs were deployed along a 710-km-long seismic refraction line, from Baffin Island to Greenland. Multichannel seismic reflection, gravity and magnetic anomaly data were recorded along the same transect. Using forward modelling and inversion of observed traveltimes from dense airgun shots, a P-wave velocity model was obtained. The detailed morphology of the basement was constrained using the seismic reflection data. A 2-D density model supports and complements the P-wave modelling. Sediments of up to 6 km in thickness with P-wave velocities of 1.8-4.0 km s−1 are imaged in the centre of Baffin Bay. Oceanic crust underlies at least 305 km of the profile. The oceanic crust is 7.5 km thick on average and is modelled as three layers. Oceanic layer 2 ranges in P-wave velocity from 4.8 to 6.4 km s−1 and is divided into basalts and dykes. Oceanic layer 3 displays P-wave velocities of 6.4-7.2 km s−1. The Greenland continental crust is up to 25 km thick along the line and divided into an upper, middle and lower crust with P-wave velocities from 5.3 to 7.0 km s−1. The upper and middle continental crust thin over a 120-km-wide continent-ocean transition zone. We classify this margin as a volcanic continental margin as seaward dipping reflectors are imaged from the seismic reflection data and mafic intrusions in the lower crust can be inferred from the seismic refraction data. The profile did not reach continental crust on the Baffin Island margin, which implies a transition zone of 150 km length at most. The new information on the extent of oceanic crust is used with published poles of rotation to develop a new kinematic model of the evolution of oceanic crust in southern Baffin Bay. [ABSTRACT FROM AUTHOR]

A P-wave velocity model along a 565-km-long profile across the Grand Banks–Newfoundland Basin rifted margin is presented. Continental crust ∼36 km thick beneath the Grand Banks is divided into upper (5.8–6.25 km s−1), middle (6.3–6.53 km s−1) and lower crust (6.77–6.9 km s−1), consistent with velocity structure of Avalon zone Appalachian crust. Syn-rift sediment sequences 6–7 km thick occur in two primary layers within the Jeanne d'Arc and the Carson basins (∼3 km s−1 in upper layer; ∼5 km s−1 in lower layer). Abrupt crustal thinning (Moho dip ∼35°) beneath the Carson basin and more gradual thinning seaward forms a 170-km-wide zone of rifted continental crust. Within this zone, lower and middle continental crust thin preferentially seawards until they are completely removed, while very thin (<3 km) upper crust continues ∼60 km farther seawards. Adjacent to the continental crust, high-velocity gradients (0.5–1.5 s−1) define an 80-km-wide zone of transitional basement that can be interpreted as exhumed, serpentinized mantle or anomalously thin oceanic crust, based on its velocity model alone. We prefer the exhumed-mantle interpretation after considering the non-reflective character of the basement and the low amplitude of associated magnetic anomalies, which are atypical of oceanic crust. Beneath both the transitional basement and thin (<6 km) continental crust, a 200-km-wide zone with reduced mantle velocities (7.6–7.9 km s−1) is observed, which is interpreted as partially (<10 per cent) serpentinized mantle. Seawards of the transitional basement, 2- to 6-km-thick crust with layer 2 (4.5–6.3 km s−1) and layer 3 (6.3–7.2 km s−1) velocities is interpreted as oceanic crust. Comparison of our crustal model with profile IAM-9 across the Iberia Abyssal Plain on the conjugate Iberia margin suggests asymmetrical continental breakup in which a wider zone of extended continental crust has been left on the Newfoundland side. [ABSTRACT FROM AUTHOR]

The central Nova Scotia margin off Eastern Canada is located at a transition from a volcanic margin in the south to a non-volcanic margin in the north. In order to study this transition, a wide-angle refraction seismic line with dense airgun shots was acquired across the central Nova Scotia margin. The 500-km-long transect is coincident with previous deep reflection profiles across the Lahave Platform and extending into the Sohm Abyssal Plain. A P-wave velocity model was developed from forward and inverse modelling of the wide-angle data from 21 ocean bottom seismometers and coincident normal-incidence reflection profiles. The velocity model shows that the continental crust is divided into three layers with velocities of 5.5–6.9 km s−1. The maximum thickness is 36 km. A minor amount (∼5 km) of thinning occurs beneath the outer shelf, while the major thinning to a thickness of 8 km occurs over the slope region. The seaward limit of the continental crust consists of 5-km-thick highly faulted basement. There is no evidence for magmatic underplating beneath the continental crust. On the contrary, a 4-km-thick layer of partially serpentinized mantle (7.6–7.95 km s−1) begins beneath the highly faulted continental crust, and extends ∼200 km seawards, forming the lower part of the ocean-continent transition zone. The upper part of the transition zone consists of the highly faulted continental crust and 4- to 5-km-thick initial oceanic crust. The continent–ocean boundary is moved ∼50 km farther seawards compared to an earlier interpretation based only on reflection seismic data. The oceanic crust in the transition zone consists of layer 2 and a high-velocity lower crustal layer. Layer 2 is 1–3 km thick with velocities of 5.6–6.0 km s−1. The high-velocity lower crustal layer is 1–2 km thick with velocities of 7.25–7.4 km s−1, suggesting a composite layer of serpentinized peridotite and gabbroic layer 3. Oceanic crust with normal thickness of 5–7 km and more typical layer 3 with velocities of 6.95–7.3 km s−1 is observed at the seaward end of the profile. [ABSTRACT FROM AUTHOR]

The Eastern Canadian Shield Onshore–Offshore Transect (ECSOOT) of the Lithoprobe program included 1200 km of normal-incidence seismic profiles and seven wide-angle seismic profiles across Archean and Proterozoic rocks of Labrador, northern Quebec, and the surrounding marine areas. Archean crust is 33–44 km thick. P-wave velocity increases downwards from 6.0 to 6.9 km/s. There is moderate crustal reflectivity, but the reflection Moho is unclear. Archean crust that stabilized in the Proterozoic is similar except for greater reflectivity and a well-defined Moho. Proterozoic crust has similar or greater thickness, variable lower crustal velocities, and strong crustal reflectivity. Geodynamic processes of Paleoproterozoic growth of the Canadian Shield are similar to those observed in modern collisional orogens. The suturing of the Archean Core Zone and Superior provinces involved whole-crustal shearing (top to west) in the Core Zone, linked to thin-skinned deformation in the New Quebec Orogen. The Torngat Orogen sutures the Nain Province to the Core Zone and reveals a crustal root, in which Moho descends to 55 km. It formed by transpression and survived because of the lack of postorogenic heating. Accretion of the Makkovik Province to the Nain Province involves delamination at the Moho and distributed strain in the juvenile arcs. Delamination within the lower crust characterizes the accretion of Labradorian crust in the southeastern Grenville Province. Thinning of the crust northwards across the Grenville Front is accentuated by Mesozoic extension that reactivates Proterozoic shear zones. The intrusion of the Mesoproterozoic Nain Plutonic Suite is attributed to a mantle plume ponding at the base of the crust.Le transect du programme Lithoprobe des zones continentales et extracôtières de la partie est du Bouclier canadien (ECSOOT) comprend 1200 km de profils sismiques à incidence normale et sept profils sismiques à grand-angle à travers les roches archéennes et protérozoïques du Labrador, du nord du Québec et des régions marines avoisinantes. La croûte archéenne a une épaisseur de 33 à 44 km. La vitesse de l'onde P augmente vers le bas de 6,0 km s[sup -1] à 6,9 km s[sup -1] . La réflectivité crustale est modérée, mais la réflexion du Moho n'est pas claire. La croûte archéenne qui s'est stabilisée au Protérozoïque est semblable, à l'exception d'une plus grande réflectivité et une discontinuité Moho bien définie. La croûte protérozoïque présente une épaisseur similaire ou plus grande, des vitesses variables pour la croûte inférieure et une forte réflectivité de la croûte. Les processus géodynamiques de croissance du Bouclier canadien au Paléoprotérozoïque sont semblables à ceux observés dans des orogènes de collision modernes. La suture de la zone noyau archéenne et de la Province du Supérieur implique du cisaillement de la croûte entière (du haut vers l'ouest) dans la zone noyau, relié à de la déformation en couches minces dans l'orogène du Nouveau-Québec. L'orogène Torngat suture la Province de Nain à la zone noyau et révèle une racine crustale dans laquelle le Moho descend à 55 km. Cet orogène s'est formé par transpression et a survécu en raison du manque d'élévation de température post-orogénique. L'accrétion de la Province de Makkovik à la Province de Nain implique une délamination au Moho et une distribution des contraintes dans les arcs juvéniles. La délamination à l'intérieur de la croûte inférieure caractérise l'accrétion de la croûte labradorienne dans le sud-est de la Province de Grenville. Un amincissement de la croûte vers le nord à travers le front du Grenville est accentué par une extension, au Mésoprotérozoïque, qui a réactivé les zones de cisaillement protérozoïques. L'intrusion de la Suite plutonique de Nain (Mésoprotérozoïque) est attribuée à un panache du manteau stagnant à la base de la croûte.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

• Cyto- and receptor-based parcellation of macaque inferior parietal lobe (IPL). • Caudo-rostral gradients found in the architectonic organization of IPL areas. • Hierarchical analysis segregated IPL areas into rostral and caudal clusters. • Novel insights into homologies between human and macaque IPL areas. The macaque monkey inferior parietal lobe (IPL) is a structurally heterogeneous brain region, although the number of areas it contains and the anatomical/functional relationship of identified subdivisions remains controversial. Neurotransmitter receptor distribution patterns not only reveal the position of the cortical borders, but also segregate areas associated to different functional systems. Thus we carried out a multimodal quantitative analysis of the cyto- and receptor architecture of the macaque IPL to determine the number and extent of distinct areas it encompasses. We identified four areas on the IPL convexity arranged in a caudo-rostral sequence, as well as two areas in the parietal operculum, which we projected onto the Yerkes19 surface. We found rostral areas to have relatively smaller receptor fingerprints than the caudal ones, which is in an agreement with the functional gradient along the caudo-rostral axis described in previous studies. The hierarchical analysis segregated IPL areas into two clusters: the caudal one, contains areas involved in multisensory integration and visual-motor functions, and rostral cluster, encompasses areas active during motor planning and action-related functions. The results of the present study provide novel insights into clarifying the homologies between human and macaque IPL areas. The ensuing 3D map of the macaque IPL, and the receptor fingerprints are made publicly available to the neuroscientific community via the Human Brain Project and BALSA repositories for future cyto- and/or receptor architectonically driven analyses of functional imaging studies in non-human primates. [ABSTRACT FROM AUTHOR]

Cryospheric events in the Arctic Ocean have been largely studied through the imprints of ice sheets, ice shelves and icebergs in the seafloor morphology and sediment stratigraphy. Subglacial morphologies have been identified in the shallowest regions of the Arctic Ocean, up to 1200 m water depth, revealing the extent and dynamics of Arctic ice sheets during the last glacial periods. However, less attention has been given to sedimentary features imaged in the vicinity of the ice-grounded areas. Detailed interpretation of the sparse available swath bathymetry and sub-bottom profiles from the Lomonosov Ridge and the Amundsen Basin shows the occurrence of mass transport deposits (MTDs) and sediment waves in the central Arctic Ocean. The waxing and waning ice sheets and shelves in the Arctic Ocean have influenced the distribution of MTDs in the vicinity of grounding-ice areas, i.e. along the crest of Lomonosov Ridge. Due to the potential of Arctic sediments to hold gas hydrates, their destabilization should not be ruled out as trigger for sediment instability. Sediment waves formed by the interaction of internal waves that propagate along water mass interfaces with the bathymetric barrier of Lomonosov Ridge. This work describes the distribution and formation mechanisms of MTDs and sediment waves in the central Arctic Ocean in relation to grounding ice and internal waves between water masses, respectively. The distribution of these features provides new insight into past cryospheric and oceanographic conditions of the central Arctic Ocean. • Ice sheet oscillation may trigger formation of Mass Transport Deposits (MTDs). • MTDs in the Arctic Ocean reveal past locations of the ice sheet edge. • Distinct location of the ice sheet edge during Marine Isotope Stages 6 and 2 • Internal waves between water masses form sediment waves (SW) in the Arctic Ocean • MTDs and SW are related to grounding ice and oceanic flows in the Arctic Ocean. [ABSTRACT FROM AUTHOR]

Histological atlases of the cerebral cortex, such as those made famous by Brodmann and von Economo, are invaluable for understanding human brain microstructure and its relationship with functional organization in the brain. However, these existing atlases are limited to small numbers of manually annotated samples from a single cerebral hemisphere, measured from 2D histological sections. We present the first whole-brain quantitative 3D laminar atlas of the human cerebral cortex. It was derived from a 3D histological atlas of the human brain at 20-micrometer isotropic resolution (BigBrain), using a convolutional neural network to segment, automatically, the cortical layers in both hemispheres. Our approach overcomes many of the historical challenges with measurement of histological thickness in 2D, and the resultant laminar atlas provides an unprecedented level of precision and detail. We utilized this BigBrain cortical atlas to test whether previously reported thickness gradients, as measured by MRI in sensory and motor processing cortices, were present in a histological atlas of cortical thickness and which cortical layers were contributing to these gradients. Cortical thickness increased across sensory processing hierarchies, primarily driven by layers III, V, and VI. In contrast, motor-frontal cortices showed the opposite pattern, with decreases in total and pyramidal layer thickness from motor to frontal association cortices. These findings illustrate how this laminar atlas will provide a link between single-neuron morphology, mesoscale cortical layering, macroscopic cortical thickness, and, ultimately, functional neuroanatomy. Using deep learning to segment the layers of the cerebral cortex, this study presents the first whole brain quantitative atlas of cortical and laminar structure. This laminar atlas provides a novel framework for bridging between the scales of neuroscience. [ABSTRACT FROM AUTHOR]

Chronic pain patients present with cortical gray matter alterations, observed with anatomical magnetic resonance (MR) imaging. Reduced regional gray matter volumes are often interpreted to reflect neurodegeneration, but studies investigating the cellular origin of gray matter changes are lacking. We used multimodal imaging to compare 26 postmenopausal women with fibromyalgia with 25 healthy controls (age range: 50-75 years) to test whether regional gray matter volume decreases in chronic pain are associated with compromised neuronal integrity. Regional gray matter decreases were largely explained by T1 relaxation times in gray matter, a surrogate measure of water content, and not to any substantial degree by GABAA receptor concentration, an indirect marker of neuronal integrity measured with [18F] flumazenil PET. In addition, the MR spectroscopy marker of neuronal viability, N-acetylaspartate, did not differ between patients and controls. These findings suggest that decreased gray matter volumes are not explained by compromised neuronal integrity. Alternatively, a decrease in neuronal matter could be compensated for by an up regulation of GABAA receptors. The relation between regional gray matter and T1 relaxation times suggests decreased tissue water content underlying regional gray matter decreases. In contrast, regional gray matter increases were explained by GABAA receptor concentration in addition to T1 relaxation times, indicating perhaps increased neuronal matter or GABAA receptor up regulation and inflammatory edema. By providing information on the histological origins of cerebral gray matter alterations in fibromyalgia, this study advances the understanding of the neurobiology of chronic widespread pain. [ABSTRACT FROM AUTHOR]

Deep seismic data represent a key to understand the geometry and mechanism of continental rifting. The passive continental margin of NW-Africa is one of the oldest on earth, formed during the Upper Triassic–Lower Liassic rifting of the central Atlantic Ocean over 200 Ma. We present new and existing wide-angle and reflection seismic data from four study regions along the margin located in the south offshore DAKHLA, on the central continental margin offshore Safi, in the northern Moroccan salt basin, and in the Gulf of Cadiz. The thickness of unthinned continental crust decreases from 36 km in the North to about 27 km in the South. Crustal thinning takes place over a region of 150 km in the north and only 70 km in the south. The North Moroccan Basin is underlain by highly thinned continental crust of only 6–8 km thickness. The ocean–continent transition zone shows a variable width between 40 and 70 km and is characterized by seismic velocities in between those of typical oceanic and thinned continental crust. The neighbouring oceanic crust is characterized by a thickness of 7–8 km along the complete margin. Relatively high velocities of up to 7.5 km/s have been imaged between magnetic anomalies S1 and M25, and are probably related to changes in the spreading velocities at the time of the Kimmeridgian/Tithonian plate reorganization. Volcanic activity seems to be mostly confined to the region next to the Canary Islands, and is thus not related to the initial opening of the ocean, which was associated to only weak volcanism. Comparison with the conjugate margin off Nova Scotia shows comparable continental crustal structures, but 2–3 km thinner oceanic crust on the American side than on the African margin. [ABSTRACT FROM AUTHOR]

Background: Cortical injections of the vasoconstrictor endothelin-1 (ET1) have widely been used to induce focal circumscribed ischemic lesions in the motor cortex of rodents in the context of stroke recovery studies. In order to apply this model correctly, it is essential to understand the time course of regional flow changes and of the development of penumbra and infarction. Methods: Multitracer micro-PET of ET1 focal ischemia in rats was performed using [11C]-flumazenil ([11C]FMZ) as a flow- and viability tracer and [18F]-fluoromisonidazole ([18F]FMISO) as hypoxia marker in order to characterize the physiological time-course of this model. Nine adult Sprague-Dawley rats received stereotaxic injections of ET1 into the right primary motor cortex, 3 served as controls. PET imaging was started 2, 3 and 20 h after the last ET1 injection. Histology was obtained at the end of the scans. Standardized uptake value ratios reflecting cerebral blood flow (CBF), [11C]FMZ-binding and [18F]FMISO-retention were calculated for the region of hypoperfusion and the normoperfused cortex. Results: CBF in the hypoperfused cortex was significantly reduced (p < 0.01) at 5 h (0.58 ± 0.025), 6 h (0.54 ± 0.043) and 23 h (0.66 ± 0.024) compared to controls (1.00 ± 0.011) and moderately reduced (p < 0.05) in the remainder of the affected hemisphere at 5 h (0.93 ± 0.036). [11C]FMZ-binding was within the control range at all time points. Significant [18F]FMISO-retention (1.16 ± 0.091, p < 0.05) was observed only after 6 h in the ischemic core that later turned into infarct. Conclusion: ET1 injections yield reproducible, slowly developing ischemic lesions with constant levels of hypoperfusion. This multitracer micro-PET study suggests that the ET1 model is appropriate for inducing chronic circumscribed ischemic lesions but seems to be less suited for studying acute stroke pathophysiology. [ABSTRACT FROM AUTHOR]

Data from a refraction seismic profile parallel to the coast of Labrador (Canada) were used to determine the crustal structure across the boundary of the Nain and Makkovik provinces, and to look for evidence for an offshore continuation of the Mesoproterozoic Nain Plutonic Suite (NPS). Seven seismometers recorded airgun shots along the 283 km long line. P- and S-wave velocity models were developed from forward and inverse modeling of travel times. The velocity model distinguishes three distinct zones. In the Saglek block of the Nain Province, the crust is divided into three layers with P-wave velocities between 5.8 and 6.9 km/s. Farther to the south, upper crustal velocities increase to 6.3–6.5 km/s and the Poisson’s ratio increases from 0.24 to 0.27. This zone correlates with a gravity low that is interpreted to outline the offshore continuation of the NPS. The upper crustal velocities are intermediate between anorthositic and granitoid rock samples collected from the NPS. A lower crustal reflector is limited to the area underneath the NPS and may be related to dioritic magmas. Mid-crustal and lower crustal velocities do not vary along the line and no underplating was detected. Within the Makkovik Province, upper crustal velocities of 5.9–6.2 km/s may indicate a dioritic composition similar to the Island Harbour Bay plutonic suite. Moho depth varies between 28 and 36 km with the maximum beneath the NPS. The variations could not be linked to effects of the Makkovikian orogeny but are thought to relate to Mesozoic rifting in Labrador Sea. Les données d’un profil sismique réfraction parallèle à la côte du Labrador (Canada) ont servi à déterminer la structure de la croûte par-dessus la limite entre les provinces de Nain et de Makkovik et pour rechercher les preuves d’une prolongation, au large, de la suite plutonique de Nain (NPS), datant du Mésoprotérozoïque. Sept sismomètres ont enregistré des coups de canon à air le long d’une ligne d’une longueur de 283 km. Des modèles de la vitesse des ondes P et S ont été développés à partir de la modélisation directe et inverse des temps de propagation. Le modèle de vitesse différencie trois zones distinctives. Dans le bloc Saglek de la province de Nain, la croûte est divisée en trois couches où l’onde P atteint des vitesses entre 5,8 et 6,9 km/s. Plus au sud, les vitesses dans la croûte supérieure augmentent à 6,3–6,5 km/s et le coefficient de Poisson augmente de 0,24 à 0,27. Cette zone est corrélée à un creux gravimétrique qui délimiterait la continuation au large de la NPS. Les vitesses dans la croûte supérieure sont intermédiaires entre celles de roches anorthositiques et granitoïdes recueillies dans la NPS. Un réflecteur dans la croûte inférieure est limité au secteur sous la NPS et il pourrait être relié à des magmas dioritiques. Les vitesses au centre et dans la partie inférieure de la croûte ne varient pas le long de la ligne et aucun sous-placage n’a été détecté. À l’intérieur de la Province de Makkovik, des vitesses de 5,9–6,2 km/s dans la croûte supérieure peuvent indiquer une composition dioritique semblable à la suite plutonique Island Harbour Bay. La profondeur de la discontinuité Moho varie de 28 à 36 km avec un maximum sous la NPS. Les variations ne pouvaient pas être reliées aux effets de l’orogène de Makkovik, elles seraient plutôt reliées à la distension dans la mer du Labrador au Mésozoïque. [ABSTRACT FROM AUTHOR]

Deep seismic data and plate kinematic reconstructions help understand the mechanisms of rifting and opening of new oceans, basic principles of plate tectonic cycles. In this study, available deep wide-angle seismic velocity models from the Atlantic margins are reviewed and plate reconstructions used to define conjugate model pairs. The main objective was to study the question of how magma-rich and magma-poor margins develop and the role of inheritance in the break-up. We also studied the question of the mechanism of formation and the origin of transform marginal plateaus, which are typically found at the border of two ocean basins of different ages and are mostly characterized by at least one volcanic phase during their formation. The results of the study include the comparison of crustal thickness, oceanic plate thickness and the influence of volcanism along the Atlantic margins. The conjugate profiles image different degrees of asymmetry of the Atlantic Margin rifts. Marginal plateaus might form when rifting stops at barriers leading to the accumulation of heat in the mantle and increased volcanism directly before or after halting of the rifting. • Deep seismic velocity models, plate kinematic reconstructions and geological information are used. • Rifting styles and volcanic influence along the Atlantic Margins are studied. • Zones of exhumed and serpentinized upper mantle had been discovered only at magma-poor margins. • At magma-rich margins the volume of magma is largest close to transfer zones and decreases in the direction of rifting. • Sheared margins are often associated with transform marginal plateaus, which have undergone at least one volcanic phase. [ABSTRACT FROM AUTHOR]

• Multimodal analysis of macaque motor and premotor cortex reveals novel parcellation • 3D atlas with cyto- and multireceptor architectonic features of 16 (pre)motor areas • Primary motor area 4 is cyto- and receptor architectonically heterogeneous • (Pre)motor areas differ in their functional connectivity fingerprints In the present study we reevaluated the parcellation scheme of the macaque frontal agranular cortex by implementing quantitative cytoarchitectonic and multireceptor analyses, with the purpose to integrate and reconcile the discrepancies between previously published maps of this region. We applied an observer-independent and statistically testable approach to determine the position of cytoarchitectonic borders. Analysis of the regional and laminar distribution patterns of 13 different transmitter receptors confirmed the position of cytoarchitectonically identified borders. Receptor densities were extracted from each area and visualized as its "receptor fingerprint". Hierarchical and principal components analyses were conducted to detect clusters of areas according to the degree of (dis)similarity of their fingerprints. Finally, functional connectivity pattern of each identified area was analyzed with areas of prefrontal, cingulate, somatosensory and lateral parietal cortex and the results were depicted as "connectivity fingerprints" and seed-to-vertex connectivity maps. We identified 16 cyto- and receptor architectonically distinct areas, including novel subdivisions of the primary motor area 4 (i.e. 4a, 4p, 4m) and of premotor areas F4 (i.e. F4s, F4d, F4v), F5 (i.e. F5s, F5d, F5v) and F7 (i.e. F7d, F7i, F7s). Multivariate analyses of receptor fingerprints revealed three clusters, which first segregated the subdivisions of area 4 with F4d and F4s from the remaining premotor areas, then separated ventrolateral from dorsolateral and medial premotor areas. The functional connectivity analysis revealed that medial and dorsolateral premotor and motor areas show stronger functional connectivity with areas involved in visual processing, whereas 4p and ventrolateral premotor areas presented a stronger functional connectivity with areas involved in somatomotor responses. For the first time, we provide a 3D atlas integrating cyto- and multi-receptor architectonic features of the macaque motor and premotor cortex. This atlas constitutes a valuable resource for the analysis of functional experiments carried out with non-human primates, for modeling approaches with realistic synaptic dynamics, as well as to provide insights into how brain functions have developed by changes in the underlying microstructure and encoding strategies during evolution. Image, graphical abstract [ABSTRACT FROM AUTHOR]