Université de Lyon

ABSTRACT In our target article, we proposed a hub-and-processors model of technological cognition. The twelve commentaries that followed offer a rare opportunity to refine, extend and test that framework against new perspectives. We integrate their contributions into a revised synthesis. The parietal sites now gain sharper anatomical definition: core substrates of technical reasoning can be more clearly distinguished from adjacent regions supporting manipulation knowledge and mental-to-digital goal-directed conceptual transformations. The inferior frontal gyrus, in turn, emerges as a dual-function node – one that routes information across hubs while simultaneously meeting the planning and control demands of tool-related behavior. Beyond cortical organization, the commentaries push the framework toward white-matter connectivity, reward and motivational circuits, as well as affordance-based theoretical accounts spanning the physical, digital and symbolic domains. They also broaden the model’s translational scope to aging, neurodegeneration, digital inclusion, and neurorehabilitation, and open new lines of inquiry into temporal dynamics, expertise, and cognitive extension. The cumulative result is a strengthened case for a cognitive neuroscience of technology: a mechanistic, translational and lifespan-oriented program aimed at understanding how the brain supports technology use, acquires technological skills and is, over time, reshaped by sustained engagement with technological artifacts.

The study tackles the challenge of accurately modeling fracture behavior in beam lattices, which is essential for designing robust architected materials. Our research focuses on evaluating how the lattice's microstructure and material properties affect fracture toughness. We employed finite element simulations based on the Euler-Bernoulli beam theory to investigate crack propagation, using a failure criterion that initiates beam fracture when maximum axial stress exceeds critical strength. Building on observations from these simulations, we developed a multi-phase-field fracture model with Cosserat elasticity to integrate consistent toughness characteristics into a comprehensive framework for lattice design. This model was validated through experimental tests, ensuring a close match between theoretical predictions and physical reality. Our findings reveal that the energy release rate remains relatively stable during crack propagation, underscoring its reliability as a measure of the toughness of periodic lattice structures. We discovered that toughness is predominantly influenced by beam height and material properties such as tensile strength and Young's modulus, while slenderness has minimal impact. Additionally, cracks were observed to preferentially propagate along the lattice's structural directions due to stress localization effects, highlighting the importance of the microstructure in fracture behavior. The implications of this research are significant, suggesting that improved modeling of fracture in lattice structures can enhance material design reliability and optimization. This study bridges the gap between theoretical models and real-world applications, providing valuable insights for the development of advanced materials with tailored fracture properties.

International audience

Abstract Tectonic faults can slip in a spectrum of fault slip behaviors, from aseismic slip and slow ruptures to elasto‐dynamic earthquakes. Following frictional theory, laboratory experiments have shown that the basic ingredient that may control this transition is the interaction between the fault stiffness and the surrounding elastic medium. We aim at investigating the role of the loading stiffness on the seismic cycles in granular fault simulations. For this purpose, we build a numerical model based on the Discrete Element Method, inspired by laboratory friction experiments on fault gouge in the presence of an elastic loading system. The coupling between fault granular rheology and surrounding rock elasticity leads to seismic cycles with properties that are strongly influenced by the loading stiffness. Stiff fault systems generally produce frequent compactional events with limited sliding distances and low to moderate stress drops, while soft fault systems generally produce rare dilatational events with large sliding distances and stress drops. We show that, on average, simulated events are well‐described by a simple linear slip‐weakening friction law, but the weakening rate that best describes the events is tightly coupled with the loading stiffness. This contradicts the idea of an intrinsic friction law for the granular gouge layer and demonstrates the need to consider a fault as a tribological system coupling the scales of the granular gouge and of the elastic surrounding medium.

This study investigates the influence of surface roughness on contact mechanics, addressing the limitations of existing models that often rely on idealized and symmetric asperity shapes. We introduce a generalized representation of asperity geometries, including non-symmetric profiles, to better capture the diversity of surface characteristics encountered in real-world applications. By applying this parametric asperity model, we perform numerical simulations to analyze the impact of different parameters on contact behavior, effectively identifying various interaction regimes. The analysis is based on the assumption of elastic contact and focuses on two-dimensional roughness profiles characterized by surfaces that remain invariant along the axis orthogonal to the rolling direction. This approach effectively simulates geometries that display sufficient invariance along this axis, thereby representing realistic asperities in the form of streaks. Our theoretical framework quantifies the resulting analytical pressure distribution as a function of both geometric and mechanical parameters of the generalized asperities. By accommodating non-symmetric asperity geometries, our approach enhances model accuracy while significantly reducing computational time and resource requirements compared to traditional numerical methods.

BackgroundRobust and continuous in vivo differentiation of spinal tracts along the brain–spinal cord axis is limited. We stitched brain and spinal cord diffusion tensor imaging (DTI) to create continuity between the brain and cervical spinal cord, enabling tractography along the central nervous system, producing an atlas of the spinal cord white matter.Materials and methodsThis prospective pilot study included four healthy subjects. Brain and cervical spinal cord 3-T DTI acquisitions were performed. Distortions were corrected using the Functional magnetic resonance imaging of the brain Software Library (FSL) software package. A semiautomatic stitching process was achieved using cross-correlation. Once the highest correlation peak was identified, rigid registration allowed accurate image alignment and fusion. Regions of interest were drawn in the brainstem according to atlas-guided projection tracts. Fiber tracking was performed using a deterministic approach with Diffusion Spectrum Imaging (DSI) Studio.ResultsThe median fiber length from stitched-image tractography (192 mm) was significantly greater than that from both the brain (111.5 mm) and spinal cord (115 mm) fields of view. The white matter fiber atlas described: the corticospinal tract in the medial part of the lateral funiculus; the rubrospinal tract in the lateral funiculus, overlapped with the corticospinal tract; the gracilis and cuneatus tracts in the dorsal columns; the spinothalamic tract in the ventrolateral part of the spinal cord, around the ventral horn; and the spinocerebellar tracts overlapping them, in the lateral funiculus.ConclusionStitching brain and spinal cord DTI fields of view provided an in vivo spinal cord white matter atlas in humans.Relevance statementThis study provides a detailed and individualized mapping of spinal tracts, serving as a potential tool for neurosurgical planning, particularly in procedures involving intramedullary tumors. It also may enhance the accuracy of prognostic assessments in patients with spinal cord injury, multiple sclerosis, or degenerative myelopathy.Key PointsBrain and spinal cord diffusion tensor imaging scans were stitched to map spinal tracts across the central nervous system, enabling detailed three-dimensional imaging of spinal cord pathways.The resulting images showed precise locations of spinal tracts, producing an in vivo atlas of the spinal cord white matter.This tool may help surgeons plan safer operations and better predict outcomes in spinal cord disorders.Graphical

Redox‐responsive supramolecular gels involving highly ordered assemblies of small molecules that can exist in different stable oxidation states are very promising soft materials for many applications ranging from catalysis to electronics. Stimulation of such materials has however so far relied mainly on the addition of chemical fuels (oxidizing or reducing agents) which makes the reversibility of the induced phenomena intrinsically limited. In this context, electrochemical stimulation is particularly interesting but unfortunately remains largely unexplored due to major scientific and technical obstacles. Here we present the electrochemical response of a supramolecular gel obtained by self‐assembly of a low molecular weight gelator derived from 4,4′‐bipyridinium salts into chiral hollow fibers. The reduction of this viologen‐based supramolecular gel was carried out under both photochemical and electrochemical stimulation. The effects of reduction on sample composition and microstructure have been extensively studied using in operando optical microscopy and absorption spectroscopy measurements. We found that the reduction‐triggered macroscopic changes result from the dissociation of charge‐transfer complexes formed between the viologen acceptor and iodide counter‐anions to form π‐dimers. We have also developed different strategies to stimulate the viologen subunits that are embedded in the supramolecular network of the gel. The dissolution and reformation of the viologen‐based supramolecular network could thus be achieved using different electrochemical stimuli. We therefore report here one of the very first low molecular weight gels capable of undergoing a reversible electrochemically‐induced phase transition.

A hallmark of obesity is a pathological expansion of white adipose tissue (WAT), accompanied by marked tissue dysfunction and fibrosis. Autophagy promotes adipocyte differentiation and lipid homeostasis, but its role in obese adipocytes and adipose tissue dysfunction remains incompletely understood. Using a mouse model, we demonstrate that autophagy is a key tissue-specific regulator of WAT remodelling in diet-induced obesity. Importantly, loss of adipocyte autophagy substantially exacerbates pericellular fibrosis in visceral WAT. Change in WAT architecture correlates with increased infiltration of macrophages with tissue-reparative, fibrotic features. We uncover that autophagy restrains purine nucleoside metabolism in obese adipocytes. This ultimately leads to a reduced release of the purine catabolites xanthine and hypoxanthine. Purines signal cell-extrinsically for fibrosis by driving macrophage polarisation towards a tissue reparative phenotype. Our findings in mice reveal a role for adipocyte autophagy in regulating tissue purine nucleoside metabolism, thereby limiting obesity-associated fibrosis and maintaining the functional integrity of visceral WAT. Purine signals may serve as a critical balance checkpoint and therapeutic target in fibrotic diseases.

Heavy-flavor quarks produced in proton-proton (pp) collisions provide a unique opportunity to investigate the evolution of quark-initiated parton showers from initial hard scatterings to final-state hadrons. By examining jets that contain heavy-flavor hadrons, this study explores the effects of both perturbative and nonperturbative QCD on jet formation and structure. The angular differences between various jet axes, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi mathvariant="normal">Δ</a:mi> <a:msub> <a:mi>R</a:mi> <a:mrow> <a:mi>axis</a:mi> </a:mrow> </a:msub> </a:math> , offer insight into the radiation patterns and fragmentation of charm quarks. The first measurement of <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"> <d:msup> <d:mi>D</d:mi> <d:mn>0</d:mn> </d:msup> </d:math> -tagged jet axes differences in pp collisions at <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"> <f:msqrt> <f:mi>s</f:mi> </f:msqrt> <f:mo>=</f:mo> <f:mn>5.02</f:mn> <f:mtext> </f:mtext> <f:mtext> </f:mtext> <f:mi>TeV</f:mi> </f:math> by the ALICE experiment at the LHC is presented for jets with transverse momentum <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"> <h:msubsup> <h:mi>p</h:mi> <h:mi mathvariant="normal">T</h:mi> <h:mtext>ch jet</h:mtext> </h:msubsup> <h:mo>≥</h:mo> <h:mn>10</h:mn> <h:mtext> </h:mtext> <h:mtext> </h:mtext> <h:mi>GeV</h:mi> <h:mo>/</h:mo> <h:mi>c</h:mi> </h:math> and <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"> <k:msup> <k:mi>D</k:mi> <k:mn>0</k:mn> </k:msup> </k:math> mesons with <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:mrow> <m:msubsup> <m:mrow> <m:mi>p</m:mi> </m:mrow> <m:mrow> <m:mi mathvariant="normal">T</m:mi> </m:mrow> <m:mrow> <m:msup> <m:mrow> <m:mi mathvariant="normal">D</m:mi> </m:mrow> <m:mrow> <m:mn>0</m:mn> </m:mrow> </m:msup> </m:mrow> </m:msubsup> <m:mo>≥</m:mo> <m:mn>5</m:mn> <m:mtext> </m:mtext> <m:mtext> </m:mtext> <m:mi>GeV</m:mi> <m:mo>/</m:mo> <m:mi>c</m:mi> </m:mrow> </m:math> . In this <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"> <q:msup> <q:mi>D</q:mi> <q:mn>0</q:mn> </q:msup> </q:math> -meson-tagged jet measurement, three jet axis definitions, each with different sensitivities to soft, wide-angle radiation, are used: the standard axis, soft drop groomed axis, and winner-takes-all axis. Measurements of the radial distributions of <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"> <s:msup> <s:mi>D</s:mi> <s:mn>0</s:mn> </s:msup> </s:math> mesons with respect to the jet axes, <u:math xmlns:u="http://www.w3.org/1998/Math/MathML" display="inline"> <u:mrow> <u:mi mathvariant="normal">Δ</u:mi> <u:msub> <u:mrow> <u:mi>R</u:mi> </u:mrow> <u:mrow> <u:mrow> <u:mi>axis</u:mi> </u:mrow> <u:mtext>−</u:mtext> <u:msup> <u:mrow> <u:mi mathvariant="normal">D</u:mi> </u:mrow> <u:mrow> <u:mn>0</u:mn> </u:mrow> </u:msup> </u:mrow> </u:msub> </u:mrow> </u:math> , are reported, along with the angle, <y:math xmlns:y="http://www.w3.org/1998/Math/MathML" display="inline"> <y:mi mathvariant="normal">Δ</y:mi> <y:msub> <y:mi>R</y:mi> <y:mrow> <y:mi>axis</y:mi> </y:mrow> </y:msub> </y:math> , between the three jet axes. The <bb:math xmlns:bb="http://www.w3.org/1998/Math/MathML" display="inline"> <bb:msup> <bb:mi>D</bb:mi> <bb:mn>0</bb:mn> </bb:msup> </bb:math> meson emerges as the leading particle in these jets, closely aligning with the winner-takes-all axis and diverging from the standard jet axis. The results also examine how varying the sensitivity to soft radiation with grooming influences the orientation of the soft drop jet axis and uncover that charm-jet structure is more likely to survive grooming when the soft drop axis is further from the <db:math xmlns:db="http://www.w3.org/1998/Math/MathML" display="inline"> <db:msup> <db:mi>D</db:mi> <db:mn>0</db:mn> </db:msup> </db:math> direction, providing further evidence of the dead-cone effect recently measured by ALICE.

ABSTRACTMetabolic dysfunction‐associated steatotic liver disease (MASLD) is a global condition linked to obesity. Totum‐448, a polyphenol‐rich blend of five plant extracts and choline, was developed to target MASLD progression. This study evaluated the dose‐dependent effects of Totum‐448 and their sustainability after supplementation cessation on MASLD features and cecal microbiota. Male hamsters were fed a normal diet, a Western diet (WD), or WD supplemented with Totum‐448 (3.5% or 5% w/w) for 12 weeks (dose–response study). A parallel 18‐week on/off study included 12 weeks of Totum‐448 (5% w/w) followed by a 6‐week cessation period. Totum‐448 dose‐dependently reduced hepatic and circulating triglycerides, total cholesterol, and free fatty acids, independently of any changes in body composition. Gene markers of liver inflammation (Tgfb1, Il1b, Ccl2, Il6) and fibrosis (Col3a1, Vcam) were downregulated with the highest dose of Totum‐448 only. Supplementation cessation led to a gradual rebound in serum and liver lipid levels and in relative expression of gene markers of hepatic inflammation and fibrosis, resulting in the loss of the majority of the benefits conferred by Totum‐448, although partial effects on hepatic steatosis and hepatocyte ballooning were maintained. Cecal microbiota analysis revealed modulation of the relative abundance of Acetatifactor, Alloprevotella, Lactobacillus, and Lawsonibacter, with identified correlations with certain metabolic outcomes. In conclusion, Totum‐448 demonstrated dose‐dependent improvements in key MASLD features in WD‐fed hamsters which gradually diminished after supplementation stopped. These findings underscore its therapeutic potential in MASLD management. The correlations with microbiota changes suggest a possible gut–liver axis role in its effects.