Biology subjects

Koren, Y.

Publications and source records attributed to Koren, Y..

5 recordsLinked to original sources

bioRxiv2026

From Arm to Leg: A Shared Primitive Framework for Solving Inverse Kinematics in Human Movement

In motor control, the idea of a modular control architecture has been repeatedly discussed. This framework has been widely applied to kinematic and kinetic data, primarily to examine how the central nervous system (CNS) controls multiple elements simultaneously and how it handles redundant or excessive degrees of freedom. However, the inverse kinematics problem, traditionally defined as the mapping from a desired task-space outcome to the corresponding joint-space solution, has usually been treated separately from this framework. Recent work from our laboratory suggests that modular control may directly address all these problems by relying on a shared low-dimensional primitive space common to internal and external movement representations, as supported by recent studies of human hand-drawing kinematics. In the present study, we extended this framework from upper-limb drawing to lower-limb gait kinematics. We also used it to explore how different CNS pathologies may alter the organization of movement within this shared space. Overall, this study investigates whether walking, like other forms of movement, can be understood as arising from a small number of underlying primitives that are flexibly combined across coordinate systems.

neuroscience↗

bioRxiv2026

Dynamic Regulation of CD300b, and CD300f on Myeloid Cells in Oral Immunotherapy

IntroductionOral immunotherapy (OIT) induces desensitization in IgE-mediated food allergy, yet the role of myeloid cells in acquisition of tolerance is unclear. CD300 receptors regulate activation of myeloid cells, with CD300f acting as an inhibitory receptor and CD300b as an activating receptor. Their modulation during OIT may reflect effector cell reprogramming and serve as biomarkers of treatment response. MethodsThirty-five patients undergoing OIT were prospectively enrolled. Peripheral blood was collected at baseline and first 3 months of up-dosing; 19 patients completed sampling upon reaching maintenance. CD300b and CD300f expression in eosinophils, monocytes, and neutrophils was analyzed by flow cytometry. Allergen-specific IgE and IgG4 were measured by ImmunoCAP. Associations with clinical parameters were assessed using logistic regression. Results. Baseline CD300b was higher in patients with lower starting doses (p[≤]0.05). CD300f expression was lower in those with atopic dermatitis or multiple food allergies (p[≤]0.03). A significant downregulation of CD300b expression in the surface of eosinophils, monocytes, and neutrophils, was noted early in treatment (p[≤]0.05). Expression of CD300f was slightly but non-significantly increased. Longitudinally, the expression of CD300f increased on eosinophils, whereas CD300b expression decreased on the surface of monocytes and neutrophils. Specific IgE reduction correlated with downregulation of CD300b expression in monocytes (R=0.51, p=0.02) and higher CD300f expression in eosinophils (R=-0.45, p=0.05). ConclusionsDownregulation of CD300b and upregulation of CD300f during OIT suggests myeloid cell reprogramming toward a less inflammatory phenotype. These dynamic changes in expression and their correlation with serologic markers of desensitization, suggest CD300b and CD300f as candidate biomarkers for understanding and monitoring OIT response. Key MessageO_LIOIT is associated with downregulation of the activating receptor CD300b and upregulation of the inhibitory receptor CD300f on myeloid cells. C_LIO_LIMyeloid cell reprogramming accompanies OIT, extending immune tolerance beyond adaptive regulatory mechanisms. C_LIO_LICD300b and CD300f expression dynamics correlate with clinical dosing and serologic markers of OIT response. C_LI

immunology↗

bioRxiv2024

The growth-driven penetration strategy of plant roots is mechanically more efficient than pushing

Plant roots are considered highly efficient soil explorers. As opposed to the push-driven penetration strategy commonly used by many digging organisms, roots penetrate by growing, adding new cells at the tip, and elongating over a well-defined growth zone. However, a comprehensive understanding of the mechanical aspects associated with root penetration is currently lacking. We perform penetration experiments following Arabidopsis thaliana roots growing into an agar gel environment, and a needle of similar dimensions pushed into the same agar. We measure and compare the environmental deformations in both cases by following the displacement of fluorescent beads embedded within the gel, combining confocal microscopy and Digital Volume Correlation (DVC) analysis. We find that deformations are generally smaller for the growing roots. To better understand the mechanical differences between the two penetration strategies we develop a computational model informed by experiments. Simulations show that, compared to push-driven penetration, grow-driven penetration reduces frictional forces and mechanical work, with lower propagation of displacements in the surrounding medium. These findings shed light on the complex interaction of plant roots with their environment, providing a quantitative understanding based on a comparative approach.

biophysics↗

bioRxiv2020

Quantifying the dynamics of long-range cell-cell mechanical communication

Cells sense, manipulate and respond to their mechanical microenvironment in a plethora of physiological processes, yet the understanding of how cells transmit, receive and interpret environmental cues to communicate with distant cells is severely limited due to lack of tools to quantitatively infer the complex tangle of dynamic cell-cell interactions in complicated environments. We present a computational method to systematically infer and quantify long-range cell-cell force transmission through the extracellular matrix (cell-ECM-cell communication) by correlating ECM remodeling fluctuations in between communicating cells and demonstrating that these fluctuations contain sufficient information to define unique signatures that robustly distinguish between different pairs of communicating cells. We demonstrate our method with finite element simulations and live 3D imaging of fibroblasts and cancer cells embedded in fibrin gels. While previous studies relied on the formation of a visible fibrous band extending between cells to inform on mechanical communication, our method detected mechanical propagation even in cases where visible bands never formed. We revealed that while contractility is required, band formation is not necessary, for cell-ECM-cell communication, and that mechanical signals propagate from one cell to another even upon massive reduction in their contractility. Our method sets the stage to measure the fundamental aspects of intercellular long-range mechanical communication in physiological contexts and may provide a new functional readout for high content 3D image-based screening. The ability to infer cell-ECM-cell communication using standard confocal microscopy holds the promise for wide use and democratizing the method.

cell biology↗

bioRxiv2020

Downward Gazing for Steadiness

When walking on an uneven surface or complex terrain, humans tend to gaze downward. Previous investigations indicate that visual information can be used for online control of stepping. Behavioral investigations suggest that, during walking, the availability of visual information increases stepping accuracy, but probably through a feedforward control mechanism. Consequently, downward gazing (DWG) is usually interpreted as a strategy used to acquire useful information for online and/or feedforward control of stepping. Visual information is not exclusively used for guiding locomotion; a wealth of literature has been published on the usefulness of visual information for feedback postural control. Critically, postural control has been shown to be sensitive to the visual flow arising from the respective motion of the individual and the 3D environment. To investigate whether DWG can be used to enhance feedback control of posture, rather than feedforward/online control of gait, we conducted a series of experiments that explore this possible interplay. Through these experiments we were able to show that DWG, just a few steps ahead, results in a steadier standing and walking posture, without the need for accuracy. Moreover, we were able to demonstrate that humans resort to DWG when walking stability is compromised, even when destabilizing features were visually unpredictable. This series of experiments provides sufficient evidence of the possible interplay between visual information used for guiding locomotion and that used for postural control. Moreover, this evidence raises concerns regarding the way we interpret gaze behavior without the knowledge of the type and use of the information gathered.

neuroscience↗