Science Society

Dr. Anna Schroeder, a leading neuroscientist, graces our show in this episode to shed light on a crucial yet understudied facet of neocortical circuits. Top-down projections in our brain act as a bridge between previous experiences, current objectives, and the sensory neocortex, playing a pivotal role in our perception and memory. While excitatory pathways have been typically associated with top-down control, inhibitory top-down projections remain a largely uncharted territory.

Dr. Schroeder's ground-breaking research, employing a unique blend of synaptic two-photon calcium imaging, circuit mapping, cortex-dependent learning, and chemogenetics in mice, uncovers the GABAergic afferents from the subthalamic zona incerta as a significant source of top-down input to the neocortex. The zona incerta's inhibitory projections are critical for learning, as they transmit integrated top-down information that is essential for encoding sensory stimuli.

Perhaps the most striking revelation from Dr. Schroeder's research is the bidirectional encoding of learned top-down relevance by the incertocortical afferents, which stands out from traditional excitatory pathways. These afferents form a disinhibitory circuit, and it is the swift appearance of negative responses that primarily drives changes in stimulus representation.

Through her findings, Dr. Schroeder provides a compelling perspective on the unique contribution of long-range (dis)inhibitory afferents to the computational flexibility of neocortical circuits.

Dr. Anna Schroeder, Neocortical Circuits, GABAergic Afferents, Zona Incerta, Top-Down Projections, Sensory Neocortex, Two-Photon Calcium Imaging, Circuit Mapping, Cortex-Dependent Learning, Chemogenetics, Disinhibitory Circuit.

Inhibitory top-down projections from zona incerta mediate neocortical memory https://doi.org/10.1016/j.neuron.2022.12.010

In this fascinating episode, Dr. McConohy dives deep into the intricacies of solid electrolytes in rechargeable lithium-metal batteries, and how they are susceptible to short-circuiting during plating. He presents a comprehensive investigation into the effect of both locally and globally applied stress on lithium penetration initiation in LLZO (Li6.6La3Ta0.4Zr1.6O12), using the method of operando microprobe scanning electron microscopy. Dr. McConohy's detailed statistical analysis demonstrates that lithium intrusion follows a Weibull distribution, and intriguingly, he unveils how an increased microprobe-LLZO contact force can significantly reduce the characteristic failure diameter of lithium metal. Further, he talks about how the direction of intrusion propagation can be manipulated using a 0.070% compressive strain via operando cantilever beam-bending experiments. Tune in to understand the complex interplay of current focusing, nanoscale cracks, and their role in lithium intrusion into the electrolyte, providing valuable insights into the mechanical tunability of electrochemical plating reactions in brittle solid electrolytes.

Lithium-metal batteries, Solid electrolytes, Lithium penetration, Stress, LLZO, Operando microprobe scanning electron microscopy, Weibull distribution, Intrusion propagation, Nanoscale cracks, Mechanical tunability, Electrochemical plating reactions.

McConohy, G., Xu, X., Cui, T. et al. Mechanical regulation of lithium intrusion probability in garnet solid electrolytes. Nat Energy (2023). https://doi.org/10.1038/s41560-022-01186-4

In this enlightening episode, we are joined by Dr. Felsche who explores the pressing issue of prolonged heat periods that have become a prominent feature of European climate. Despite their recurrence, knowledge about the dominant spatial patterns of heatwaves and their impact on moisture-related processes remains sparse. Dr. Felsche discusses how gaining insights into these patterns could significantly improve heatwave and drought prediction, and thus lead to effective mitigation strategies.

He describes how they used hierarchical agglomerative clustering to determine nine dominant spatial heatwave patterns based on a 50-member regional climate model (Canadian Regional Climate Model version 5, CRCM5-LE). Interestingly, these patterns align well with clusters derived from an observational dataset (E-OBS) and with records of extreme historical heatwave events.

Dr. Felsche then delves into the intricate relationship between the occurrence of heatwaves and the soil moisture deficit present both before and after these events. Discover how negative soil moisture anomalies in the preceding winter/spring can act as a predictor for heatwaves in Southern Europe, and how North Europe exhibits a negative correlation between the number of heatwave days in summer and autumn soil moisture content.

Join us as we unlock crucial understanding about the spatial patterns and environmental effects of heatwaves.

Heatwaves, European climate, Spatial patterns, Moisture-related processes, Hierarchical agglomerative clustering, Regional climate model, CRCM5-LE, E-OBS, Soil moisture deficit, Drought prediction, Climate mitigation strategies.

Felsche, E., Böhnisch, A. & Ludwig, R. Inter-seasonal connection of typical European heatwave patterns to soil moisture. npj Clim Atmos Sci 6, 1 (2023). https://doi.org/10.1038/s41612-023-00330-5

In this fascinating episode, we delve into the realm of bioarchaeology and genomics with Dr. Raquel Fleskes and Dr. Theodore Schurr. Their groundbreaking work, the Anson Street African Burial Ground Project, investigated the lives of thirty-six 18th-century individuals from Charleston, South Carolina.

The duo provides insights into their research methods, and how they managed to generate low coverage genomic data from 18 of these individuals. This data unveiled a wide spectrum of ancestral connections across Western Africa, including one individual with genomic affiliations with the Fulani peoples of West Africa.

This project represents the largest number of ancient genomes from African-descended persons in North America ever studied. It is a substantial leap forward in enhancing our understanding of African diversity and history in colonial America.

Dr. Fleskes and Dr. Schurr further discuss the critical role of community-engaged research, and how their study, initiated in close collaboration with the Gullah Society of Charleston and other community members, exemplifies this practice.

Join us as we unravel the complex tapestry of colonial histories and uncover the stories of these ancestors, previously obscured by time and oppression.

Bioarchaeology, Genomics, Anson Street African Burial Ground Project, Colonial America, African diversity, Paleogenomics, Genetic origins, African-descendant populations, Community-engaged research, Gullah Society, West and West-Central African ancestry.

Community-engaged ancient DNA project reveals diverse origins of 18th-century African descendants in Charleston, South Carolina https://doi.org/10.1073/pnas.2201620120

Join us in this enlightening episode as we chat with Dr. Gabert about his innovative work in the development of robotic leg prostheses. His pioneering research is set to enhance the mobility and quality of life of millions of individuals with lower-limb amputations.

Dr. Gabert presents a unique robotic leg prosthesis that not only emulates the essential biomechanical functions of the biological knee, ankle, and toe, but also manages to match the weight, size, and battery life of conventional microprocessor-controlled prostheses.

Learn about the impressive torque-sensitive mechanism powering the knee joint and the compliant, underactuated system operating the ankle and toe joints. These components allow for substantial mechanical energy regeneration and closely mimic the key biomechanical functions of the ankle/foot complex during walking.

Dr. Gabert further elaborates on the practical aspects of this prosthesis, discussing how all mechanical and electrical components are enclosed within a compact frame for improved robustness and efficiency.

With clinical tests showing promising results, this innovative prosthetic design holds the potential to significantly improve the real-world mobility of individuals with above-knee amputation.

Robotic leg prosthesis, Biomechanics, Lower-limb amputations, Torque-sensitive mechanism, Underactuated system, Mechanical energy regeneration, Above-knee amputation, Robustness, Efficiency, Mobility improvement.

A lightweight robotic leg prosthesis replicating the biomechanics of the knee, ankle, and toe joint https://doi.org/10.1126/scirobotics.abo3996

In this enlightening episode, Dr. Hermundur Sigmundsson delves into an innovative approach to improve reading skill development in children, based on his groundbreaking work in Iceland.

His perspective, referred to as 'READ', incorporates the phonics approach to reading achievement, which emphasizes the importance of teaching children how to decipher the reading code. Additionally, 'READ' merges key concepts from theories of learning and skill development, such as 'deliberate practice' and 'flow'.

Dr. Sigmundsson discusses how 'deliberate practice', a concept developed by Ericsson, involves baseline measurements that provide a foundation for follow-up and intentional practice. Coupled with the concept of 'flow', coined by Csikszentmihalyi, where challenges are always in relation to the skills, this ensures every child can experience a state of 'flow', feeling a sense of mastery and competence.

He further explores how the training hour allows children to strengthen the neural network used for specific skills being trained, with letter-sound knowledge being practiced until the child has cracked the reading code.

Dr. Sigmundsson shares promising results from the first-year trial in Vestmannaeyjar school in Iceland, where all the children were able to read simple words, 96% were able to read sentences, and 88% could read text. This episode invites an engaging discussion around Ericsson’s and Csikszentmihalyi’s influential theories and their application in reading skill development.

Reading skill development, Phonics approach, Learning theories, Deliberate practice, Flow, Mastery, Neural network, Letter-sound knowledge, Reading code, Ericsson, Csikszentmihalyi.

Sigmundsson, H.; Thórsdóttir, H.S.; Njálsdóttir, H.R.; Hjaltalín, S.T. Reading: From the Simple to the Complex. Brain Sci. 2022,12,1670.

https://doi.org/10.3390/brainsci12121670

In this episode, Dr. Aleksandra Serafin shares her revolutionary work on using electroconductive scaffolds for spinal cord injury (SCI) repair. Despite the hostile environment post-SCI that hampers neuronal track re-establishment, her research is offering promising prospects for SCI tissue engineering (TE) treatment strategies.

Dr. Serafin discusses the limitations of existing conductive polymers, like poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), due to their suboptimal biofunctionality and biocompatibility. She elucidates her innovative solution, synthesizing PEDOT nanoparticles (NPs) via chemical oxidation polymerization in miniemulsion, which are then incorporated with gelatin and hyaluronic acid (HA) to create gel:HA:PEDOT-NPs scaffolds.

She shares her comprehensive study results, detailing scaffold characteristics including increased conductivity, controlled porosity, and a compressive modulus tailored to match the native spinal cord. Also noteworthy are the excellent 3D shear-thinning printing capabilities of the hydrogel and the superior shape fidelity post-printing.

Highlighting in-vitro and in-vivo study outcomes, Dr. Serafin reveals how these scaffolds exhibit cytocompatibility and positively influence signal re-establishment and the initiation of healing mechanisms in a rat SCI model. In particular, the HA in the scaffold demonstrates immunomodulatory properties, controlling inflammatory response and limiting scar formation, thereby enhancing axonal migration towards the implantation site.

Through her research, Dr. Serafin convincingly demonstrates the potential of gel:HA:PEDOT-NPs scaffolds as a promising TE solution for SCI regeneration, paving the way for future treatments.

Key Words: Spinal Cord Injury, Electroconductive Scaffolds, Tissue Engineering, Conductive Polymers, PEDOT:PSS, PEDOT Nanoparticles, Gel:HA:PEDOT-NPs Scaffolds, Cytocompatibility, Axonal Migration, Hyaluronic Acid, Immunomodulatory Properties, Regeneration.

Serafin, A., Rubio, M.C., Carsi, M. et al. Electroconductive PEDOT nanoparticle integrated scaffolds for spinal cord tissue repair. Biomater Res (2022). https://doi.org/10.1186/s40824-022-00310-5

In this enlightening episode, Dr. Martín-Zamora takes listeners on a deep dive into the complex world of larvae evolution and how temporal shifts in trunk formation underpin the diversification of larvae and bilaterian life cycles. Despite larvae's central role in animal evolution scenarios across all major animal lineages, the understanding of how larvae evolved remains elusive. Dr. Martín-Zamora's groundbreaking research seeks to fill this knowledge gap.

Dr. Martín-Zamora presents his study, where chromosome-scale genome sequencing was performed on the annelid Owenia fusiformis, combined with transcriptomic and epigenomic profiling during the life cycles of this species and two other annelids. His research reveals that trunk development in O. fusiformis is postponed to pre-metamorphic stages in the feeding larva, in contrast to the non-feeding larva of Capitella teleta and the directly developing embryo of Dimorphilus gyrociliatus where it begins post-gastrulation.

His findings also highlight that the embryos of O. fusiformis first develop into an enlarged anterior domain, forming larval tissues and the adult head. This is consistent with observations in the so-called 'head larvae' of other bilaterians, showing extensive transcriptomic similarities with the O. fusiformis larva.

Dr. Martín-Zamora posits that the temporal decoupling of head and trunk formation seen in head larvae may have facilitated larval evolution in Bilateria. This new perspective offers an intriguing departure from traditional theories that attribute larva and adult origins to co-option or innovation of gene regulatory programs.

Key Words: Larvae Evolution, Bilaterian Life Cycles, Temporal Shifts, Trunk Formation, Annelids, Owenia fusiformis, Genome Sequencing, Transcriptomic Profiling, Epigenomic Profiling, Head Larvae, Gene Regulatory Programs, Animal Evolution.

Martín-Zamora, F.M., Liang, Y., Guynes, K. et al. Annelid functional genomics reveals the origins of bilaterian life cycles. Nature (2023). https://doi.org/10.1038/s41586-022-05636-7

In this exciting episode, Dr. Long Zhang discusses his groundbreaking research on developing a molecular electric motor. The conversation explores the implications and potential of such technology, especially considering the vast influence of macroscopic electric motors on modern society.

Dr. Zhang shares details about the construction of a molecular electric motor based on a [3]catenane, which involves two cyclobis(paraquat-p-phenylene) (CBPQT4+) rings powered by electricity to circumrotate unidirectionally around a 50-membered loop. The motor's design ensures that both rings perform highly unidirectional movement, guided by a flashing energy ratchet.

The conversation deepens as Dr. Zhang explains the mechanism behind the unidirectional movement, powered by an oscillating voltage or external modulation of the redox potential. Although initial efforts on a homologous [2]catenane proved insufficient to support unidirectional movement, the incorporation of a second CBPQT4+ ring provided the necessary symmetry breaking.

The significant achievement of Dr. Zhang's research lies in its waste-free operation, a unique aspect of these electric molecular motors. This development represents an essential stride towards the actualization of surface-bound electric molecular motors, holding potential implications for a range of technologies and industries.

Key Words: Molecular Motors, Electric Motors, [3]Catenane, Cyclobis(paraquat-p-phenylene), Unidirectional Movement, Flashing Energy Ratchet, Oscillating Voltage, Redox Potential, Symmetry Breaking, Electrically Driven Circumrotatory Motion, Surface-Bound Electric Molecular Motors.

Zhang, L., Qiu, Y., Liu, WG. et al. An electric molecular motor. Nature 613, 280–286 (2023). https://doi.org/10.1038/s41586-022-05421-6

Dr. Aneesh Bose joins us in this insightful episode to discuss the growing problem of pharmaceutical pollution and its potential impact on ecosystems worldwide. With pharmaceutical drugs increasingly detected in wildlife tissues, Dr. Bose highlights the urgent need to understand the effects of these pollutants on natural ecosystems.

This episode dives into Dr. Bose's innovative research involving larval odonates (dragonfly and damselfly nymphs). His team investigated the effects of exposure to two pharmaceuticals, cetirizine and citalopram, and their combination on predator-prey interactions.

Dr. Bose shares fascinating findings, which showed that exposure to both compounds increased dragonfly activity and influenced their predation success and efficiency in complex ways. He explains that while citalopram exposure reduced predation efficiency, cetirizine exposure led to diverse effects, enhancing predation success in some contexts but impairing it in others.

These findings emphasize the importance of examining the effects of pharmaceuticals in various contexts. Furthermore, Dr. Bose explains how such compounds can alter predator-prey outcomes, even at sublethal concentrations.

Tune in to learn more about this emerging environmental threat and how it can reshape our understanding of ecosystem dynamics.

Key Words: Pharmaceutical Pollution, Ecosystems, Predator-Prey Interactions, Odonate Nymphs, Cetirizine, Citalopram, Predation Efficiency, Sublethal Concentrations, Environmental Threat, Dragonflies, Damselflies.

Pharmaceutical pollution disrupts the behavior and predator-prey interactions of two widespread aquatic insects https://doi.org/10.1016/j.isci.2022.105672