Science Society – Détails, épisodes et analyse

In this captivating episode, we dive deep into the intersection of mathematics and neuroscience with Dr. Dimitris Pinotsis. Boasting a PhD in Mathematics and an MSc in Theoretical Physics from the renowned University of Cambridge, Dimitris' academic journey is truly impressive. After publishing numerous papers in mathematics and physics, he shifted his focus to his true passion: neuroscience. His collaborations with leading minds in the field, such as Peter Grindrod, Karl Friston, and Earl Miller, have fortified his expertise in machine learning and developing mathematical methods to analyze brain data.Currently positioned as an Associate Professor at City—University of London and maintaining a Research Affiliate status at MIT's Brain and Cognitive Sciences Department, Dimitris has earned numerous accolades in his career. His commitment to the field is evident from receiving multiple fellowships from prestigious institutions to being honored with several awards, including the Poincare Institute Award.In this episode, we'll also unpack his latest paper which explores a groundbreaking concept: how does the brain's anatomy influence its function? Contrary to the prevailing view, Dimitris and his team propose that the geometry of the brain plays a more pivotal role in its dynamics than previously believed. Through analysis of human MRI data, the team presents evidence that brain activity can be better understood by examining the resonant modes of the brain's geometry instead of just its complex interregional connectivity. This finding has far-reaching implications, reshaping our understanding of how task-evoked activations span across the brain and the role of wave-like activity.Join us as we traverse the intersections of math, brain anatomy, and function, unveiling the mysteries of the human mind with Dr. Dimitris Pinotsis.Pang, J.C., Aquino, K.M., Oldehinkel, M. et al. Geometric constraints on human brain function. Nature 618, 566–574 (2023). https://doi.org/10.1038/s41586-023-06098-1Keywords: Theoretical Neuroscience, Cambridge, Machine Learning, Predictive Coding, Deep Neural Networks, Cognitive Neuroscience, Fellowships, Neural Field Theory, Brain Geometry, Magnetic Resonance Imaging, Wave Dynamics, Brain-wide Modes, Spatiotemporal Properties.

In this episode, we delve deep into the world of cognitive control with Dr. Fradkin as we discuss how people deal with unwanted thoughts. Although much research has been focused on external interferences, we shift the focus to internal, unwanted thoughts, examining the balance between reactive and proactive control in mitigating these. We discuss how reactive thought control entails slower response times due to the need to reject and replace recurring thoughts. Proactive thought control, on the other hand, implies a constricted search space leading to faster response times. With the help of a computational model, we delve deeper into proactive thought control mechanisms, exploring how individuals can reduce the episodic strengthening of repeated thoughts and avoid looping in a repetitive thought cycle. We also touch upon the link between the control over unwanted thoughts and individual differences, which can contribute to our understanding of psychiatric conditions associated with intrusive thoughts. Lastly, we discuss how associative thinking and various control processes influence semantic fluency, decision-making, and creativity.

Keywords: Cognitive Control, Unwanted Thoughts, Reactive Control, Proactive Control, Associative Thinking, Episodic Strengthening, Repetitive Thoughts, Computational Model, Semantic Fluency, Decision-Making, Creativity, Psychiatric Conditions.

Fradkin I, If you don't let it in, you don't have to get it out: Thought preemption as a method to control unwanted thoughts. doi: 10.1371/journal.pcbi.1010285. PMID: 35834438; PMCID: PMC9282588.

In this episode, we welcome Dr. Lanna, who sheds light on a novel mechanism of T-cell rejuvenation that could significantly impact our understanding of immune protection. Traditionally, it's thought that T lymphocytes activate telomerase to avoid senescence. However, Dr. Lanna introduces us to a distinct process independent of telomerase action, where certain T cells, primarily naive and central memory cells, elongate their telomeres by receiving telomere vesicles from antigen-presenting cells (APCs). She explains the fascinating process of how APCs degrade shelterin to donate telomeres, which are then cleaved by the telomere trimming factor TZAP and transferred to T cells via extracellular vesicles. We delve into how these telomere vesicles, retaining the Rad51 recombination factor, enable telomere fusion, effectively lengthening T-cell chromosome ends. Dr. Lanna discusses the implications of these antigen-specific T cell populations, whose aging decisions are based on telomere vesicle transfer, hinting at a potential mechanism for long-lasting immune protection.

Keywords: T Lymphocytes, Telomerase, Senescence, Antigen-Presenting Cells, Telomere Vesicles, TZAP, Rad51 Recombination Factor, Immune Protection, Telomere Elongation.

Lanna, A., et al. An intercellular transfer of telomeres rescues T cells from senescence and promotes long-term immunological memory. Nat Cell Biol (2022). https://doi.org/10.1038/s41556-022-00991-z

Join us in this thought-provoking episode with Dr. Dumas, where we explore the fascinating world of the developing brain and its cognitive abilities. Dr. Dumas presents a neurocomputational model of the developing brain, outlining three tasks of increasing complexity, from visual recognition to cognitive manipulation and conscious percept management. She emphasizes two crucial mechanisms in the development of cognitive abilities in biological neural networks: synaptic epigenesis and self-organized dynamics. Dr. Dumas explains the concept of synaptic epigenesis, which involves Hebbian learning at the local scale and reinforcement learning at the global scale. She also elaborates on self-organized dynamics, emphasizing the role of spontaneous activity and a balanced excitatory/inhibitory ratio in neurons. The conversation further explores the implications of these findings on future developments in artificial intelligence, underlining the core features of human intelligence that could be used as guiding principles.

Keywords: Cognitive Abilities, Neurocomputational Model, Synaptic Epigenesis, Self-Organized Dynamics, Hebbian Learning, Reinforcement Learning, Artificial Intelligence, Human Intelligence, Neurodevelopmental.

Multilevel development of cognitive abilities in an artificial neural network https://doi.org/10.1073/pnas.2201304119 This could guide future development in artificial intelligence.

Join us in a stimulating conversation with Dr. Frank as we explore the concept of intelligence on a planetary scale. Shifting away from conventional views of intelligence as a property of individuals or collectives, Dr. Frank introduces the intriguing idea that the emergence of technological intelligence could be seen as a planetary transition. Drawing parallels with theories about the origin of life as a planetary event, Dr. Frank presents a fresh perspective on the evolution of life and intelligence at the planetary level, far beyond the traditional focus on individual species. This episode delves into how this broader understanding of planetary intelligence could influence three distinct areas: Earth Systems and Exoplanet studies; Anthropocene and Sustainability studies; and Technosignatures and the Search for Extraterrestrial Intelligence (SETI). Tune in as we discuss the implications of planetary intelligence on predicting possible paths of the long-term evolution of inhabited planets, including Earth and potential extraterrestrial worlds.

Keywords: Planetary Intelligence, Earth Systems, Exoplanet Studies, Anthropocene, Sustainability, Technosignatures, Extraterrestrial Intelligence, Technological Intelligence, Evolution.

Frank, A., Grinspoon, D., & Walker, S. (2022). Intelligence as a planetary scale process. International Journal of Astrobiology, 21(2), 47-61. doi:10.1017/S147355042100029X

This episode presents a captivating discussion with James Weiss on his team's significant findings in the diverse world of microbes. Despite many microbial species escaping detection due to their low numbers or dormancy, Weiss's team has discovered the extraordinarily rare ciliate, Legendrea loyezae Fauré-Fremiet, 1908, in freshwater anoxic sediments. This discovery represents the sixth account of the ciliate since 1908. The conversation dives deep into the species' unique morphological features, such as its "shapeshifting" ability to control the full extension and retraction of its tube-like tentacles. Weiss also questions the validity of certain taxonomic decisions and proposes reclassifications based on morphological characters and tentacle movement. This episode is a testament to the rewards of persistent exploration of natural habitats and the exciting possibilities it offers for uncovering new microbial species and communities.

Keywords: Microbial Diversity, Ciliates, Legendrea loyezae, Anoxic Sediments, Microbial Communities, Taxonomy, Shapeshifting, Morphological Features.

The Extraordinarily Rare Ciliate Legendrea loyezae Fauré-Fremiet, 1908 (Haptoria, Ciliophora) by independent researcher James Weiss et al. https://doi.org/10.1016/j.protis.2022.125912

In this episode, Dr. Oliver shares his team's groundbreaking work on the use of a gallium-aluminum (Ga-Al) composite to enhance the formation of aluminum nanoparticles and facilitate water splitting to generate hydrogen at ambient conditions. He discusses how this Ga-Al composite can be synthesized using commercial aluminum, including post-consumer aluminum foil, eliminating the need for an inert atmosphere or mechanical aid. The conversation covers the scientific specifics, including the role of gallium in dissolving the aluminum oxide coating of the aluminum nanoparticles, enabling continuous water splitting and on-demand hydrogen generation through the Grotthuss mechanism. Dr. Oliver shares how the water-splitting reaction functions at ambient conditions and neutral pH and can use any source of water without generating chlorine gas. Importantly, he also highlights the reusability of gallium and how the Ga-Al alloy can be pre-prepared and stored for future use. As a practical demonstration of the potential applications of this technology, he discusses a hydrogenation reaction.

Keywords: Water Splitting, Hydrogen Generation, Gallium-Aluminum Composite, Nanoparticles, Grotthuss Mechanism, Environmental Chemistry, Sustainability, Hydrogenation.

Aluminum Nanoparticles from a Ga–Al Composite for Water Splitting and Hydrogen Generation https://doi.org/10.1021/acsanm.1c04331

In this enlightening episode, we are joined by acclaimed scientist Dr. Ed Boyden, a pioneer in the field of neuroscience. Dr. Boyden discusses the suite of tools his team is developing to map the location and identity of the molecular building blocks of biological systems like the brain, aiming to understand how their structures lead to function and dysfunction. He details the technology of expansion microscopy (ExM), which allows the imaging of preserved biological systems with nanoscale precision on ordinary microscopes. The conversation delves into his team's work on in situ RNA and DNA sequencing in intact biological systems, democratizing nanoresolution imaging, and potential applications for disease detection and understanding.

The discussion also centers around Dr. Boyden's work on recording high-speed brain dynamics, involving innovations like new fluorescent reporters of cellular signals and new robotic and nanotechnological probes. The possibilities of closed-loop brain control technologies are also considered.

Optogenetics, a field where Dr. Boyden has been instrumental, is explored extensively. Optogenetic tools allow for precise control of neural electrical activity and other physiological processes using light. The potential of these tools in neuroscience, bioengineering, and potential treatments of brain disorders is discussed.

Lastly, Dr. Boyden shares his insights on understanding normal and pathological brain computations. His team's contributions to developmental biology, cancer, microbiology, virology, immunology, and aging through the application of their technologies are touched upon. The concept of implosion fabrication (ImpFab), a technology enabling the assembly of 3D nanomaterials, is also introduced.

Keywords: Neuroscience, Brain Mapping, Expansion Microscopy, High-speed Brain Dynamics, Optogenetics, Brain Computation, Implosion Fabrication, Biological Systems, RNA sequencing, DNA sequencing.

Ed Boyden, Ph.D. Y. Eva Tan Professor in Neurotechnology at MIT develops tools that image and control the brain and apply them to solve entire brain circuits. https://syntheticneurobiology.org/