Neural computational modeling reveals a major role of corticospinal gating of central oscillations in the generation of essential tremor

Essential tremor, also referred to as familial tremor, is an autosomal dominant genetic disease and the most common movement disorder. It typically involves a postural and motor tremor of the hands, head or other part of the body. Essential tremor is driven by a central oscillation signal in the brain. However, the corticospinal mechanisms involved in the generation of essential tremor are unclear. Therefore, in this study, we used a neural computational model that includes both monosynaptic and multisynaptic corticospinal pathways interacting with a propriospinal neuronal network. A virtual arm model is driven by the central oscillation signal to simulate tremor activity behavior. Cortical descending commands are classified as alpha or gamma through monosynaptic or multisynaptic corticospinal pathways, which converge respectively on alpha or gamma motoneurons in the spinal cord. Several scenarios are evaluated based on the central oscillation signal passing down to the spinal motoneurons via each descending pathway. The simulated behaviors are compared with clinical essential tremor characteristics to identify the corticospinal pathways responsible for transmitting the central oscillation signal. A propriospinal neuron with strong cortical inhibition performs a gating function in the generation of essential tremor. Our results indicate that the propriospinal neuronal network is essential for relaying the central oscillation signal and the production of essential tremor.

Editable semiconductor photo-electrodes for sustainable ammonia synthesis

Powered by an inexhaustible supply of solar energy,photoelectrochemical(PEC)nitrogen reduction reaction(NRR)provides an ideal solution for the synthesis of green ammonia(NH_(3)).Although great efforts have been made in the past decades,there are still significant challenges in increasing the NH_(3) yields of the PEC-NRR devices.In addition to the issues of low activity and selectivity similar to electrochemical NRR,the progress of PEC-NRR is also impeded by the limited increase in NH_(3) yields as the electrode is enlarged.Here,we propose an editable electrode design strategy that parallels unit photo-electrodes to achieve a linear increase in NH_(3) yields with electrode active area.We demonstrate that the editable electrode design strategy minimizes the electrode charge transfer resistance,allowing more photo-generated carriers to reach the electrode surface and promote the catalytic reaction.We believe that this editable electrode design strategy provides an avenue to achieve sustainable PEC NH_(3) production.

Hydrogen-assisted activation of N_(2)molecules on atomic steps of ZnSe nanorods

Electrochemical reduction reaction of nitrogen(NRR)offers a promising pathway to produce ammonia(NH_(3))from renewable energy.However,the development of such process has been hindered by the chemical inertness of N_(2).It is recently proposed that hydrogen species formed on the surface of electrocatalysts can greatly enhance NRR.However,there is still a lack of atomiclevel connection between the hydrogenation behavior of electrocatalysts and their NRR performance.Here,we report an atomistic understanding of the hydrogenation behavior of a highly twinned ZnSe(T-ZnSe)nanorod with a large density of surface atomic steps and the activation of N_(2)molecules adsorbed on its surface.Our theoretical calculations and in situ infrared spectroscopic characterizations suggest that the atomic steps are essential for the hydrogenation of T-ZnSe,which greatly reduces its work function and efficiently activates adsorbed N_(2)molecules.Moreover,the liquid-like and free water over T-ZnSe promotes its hydrogenation.As a result,T-ZnSe nanorods exhibit significantly enhanced Faradaic efficiency and NH3 production rate compared with the pristine ZnSe nanorod.This work paves a promising way for engineering electrocatalysts for green and sustainable NH3 production.

Highly Selective Biomimetic Flexible Tactile Sensor for Neuroprosthetics

Biomimetic flexible tactile sensors endow prosthetics with the ability to manipulate objects,similar to human hands.However,it is still a great challenge to selectively respond to static and sliding friction forces,which is crucial tactile information relevant to the perception of weight and slippage during grasps.Here,inspired by the structure of fingerprints and the selective response of Ruffini endings to friction forces,we developed a biomimetic flexible capacitive sensor to selectively detect static and sliding friction forces.The sensor is designed as a novel plane-parallel capacitor,in which silver nanowire-3D polydimethylsiloxane(PDMS)electrodes are placed in a spiral configuration and set perpendicular to the substrate.Silver nanowires are uniformly distributed on the surfaces of 3D polydimethylsiloxane microcolumns,and silicon rubber(Ecoflex^(■))acts as the dielectric material.The capacitance of the sensor remains nearly constant under different applied normal forces but increases with the static friction force and decreases when sliding occurs.Furthermore,aiming at the slippage perception of neuroprosthetics,a custom-designed signal encoding circuit was designed to transform the capacitance signal into a bionic pulsed signal modulated by the applied sliding friction force.Test results demonstrate the great potential of the novel biomimetic flexible sensors with directional and dynamic sensitivity of haptic force for smart neuroprosthetics.

Next-Generation Prosthetic Hand:from Biomimetic to Biorealistic

Integrating a prosthetic hand to amputees with seamless neural compatibility presents a grand challenge to neuroscientists and neural engineers for more than half century.Mimicking anatomical structure or appearance of human hand does not lead to improved neural connectivity to the sensorimotor system of amputees.The functions of modern prosthetic hands do not match the dexterity of human hand due primarily to lack of sensory awareness and compliant actuation.Lately,progress in restoring sensory feedback has marked a significant step forward in improving neural continuity of sensory information from prosthetic hands to amputees.However,little effort has been made to replicate the compliant property of biological muscle when actuating prosthetic hands.Furthermore,a full-fledged biorealistic approach to designing prosthetic hands has not been contemplated in neuroprosthetic research.In this perspective article,we advance a novel view that a prosthetic hand can be integrated harmoniously with amputees only if neural compatibility to the sensorimotor system is achieved.Our ongoing research supports that the next-generation prosthetic hand must incorporate biologically realistic actuation,sensing,and reflex functions in order to fully attain neural compatibility.