Seminars

Navigation and memory require coordination between map-like allocentric representations and body-centered egocentric actions. Aaron Wilber examines how the parietal–retrosplenial–anterior thalamic–hippocampal network performs these transformations, and how disrupted coordination contributes to spatial deficits in aging and Alzheimer’s disease. Rat sequence-task experiments reveal bidirectional hippocampal–parietal interactions across route-centered, place and egocentric representations. Because that task does not isolate reference-frame use, the laboratory developed a freely available task separating egocentric, allocentric and transformation conditions. Validation indicates that parietal cortex and anterior thalamus are required for transformation; ongoing work examines population states associated with each condition. The talk then connects impaired hippocampal–cortical communication during sleep to navigation deficits in 3xTg-AD mice, reporting recovery of circuit function and cognition after early, circuit-targeted 40 Hz entrainment. Related investigations examine this network during waking navigation. In TgF344-AD rats, egocentric impairments appear before transformation deficits, addressing the shortage of rodent studies of reference-frame coordination in Alzheimer’s disease.

Marty Weissman presents a University of California, Santa Cruz course that develops mathematics for the life sciences through models of biological dynamics. Adapted from UCLA’s LS30 course, it integrates calculus, dynamical systems and linear algebra. The seminar describes the curriculum and its active learning discussion sections, where deliberate choices range from custom dynamical-system simulators to paper exercises and blackboard work. Drawing on two years of teaching, Weissman reflects on which approaches appear to support student learning and the development of the teaching team.

How do humans stabilize an inverted pendulum, and why does a balanced pole eventually fall? Drawing on 25 years of fingertip pole-balancing research, this talk examines neural correction delays: longer poles move more slowly relative to the nervous system’s response time. Delay-differential models can stabilize the upright position, yet skilled people still experience falls. The proposed explanation is microchaos arising from interactions among delay, sensory dead zones and frequency-dependent force encoding. A region of transient falling solutions lies next to stable microchaotic dynamics. Such microchaos is absent in virtual frontal-plane balancing tasks, while models of standing postural sway lack the corresponding transient regime. The comparison suggests that human falls, unlike pole falls, are more plausibly associated with medical events or slips and trips.

The 10 New Insights in Climate Science report synthesizes influential and emerging research into ten findings relevant to decision-makers ahead of international climate negotiations. This launch examines changes in the climate system, the increasing costs and consequences of warming, and the political and economic influences on climate action. Leading scientists will explain the evidence behind the 2026/27 report and its implications for policy and research ahead of COP31. The programme introduces how the synthesis is produced, presents the ten insights, develops three perspectives on translating science into action, and concludes with audience questions.

Robot missions require both collision-free trajectories and logical task ordering, such as collecting a resource before entering a restricted region. Augmented graphs of convex sets combine continuous trajectory optimization and discrete task sequencing in one problem. A layered graph constructed from an exact convex partition of free space selects an optimal task order and trajectory through a shortest-path calculation, exact up to finite Bézier parameterization. Its structure corresponds to Bellman–Held–Karp dynamic programming for the travelling-salesperson problem, retaining singly exponential worst-case complexity and improving exponentially on general temporal-logic tools. A library of specifications covers ordered collection, alternative keys, combined prerequisites, timing and conditional logic with correctness guarantees. Numerical benchmarks demonstrate exponential speedups and near-global optimality. Possible extensions include moving environments, safety-aware planning with conformal prediction sets and a large galactic-survey benchmark.

Seminar by Morten Kjaergaard (Niels Bohr Institute, University of Copenhagen) on rapid FPGA-based feedback for superconducting qubits, including sparse-sampling techniques and on-FPGA inference enabling millisecond-timescale T1 estimation, ~100 ms readout optimization, and over 74,000 consecutive recalibrations in closed-loop operation.

Anthony Letai discusses how understanding programmed cell death can guide the selection of cancer treatments. The seminar explains how apoptotic signalling can be measured and how these measurements can identify drugs capable of killing cancer cells. Hybrid: New Research Building Auditorium, Georgetown University Medical Center, Washington, DC, and Zoom. Monday 5 October 2026, 16:30–17:30 EDT (America/New_York; UTC−4). Use the attendance registration form or the event’s Zoom link on the organizer page. Organized by Georgetown’s Distinguished Scientist Seminar Series. Letai is Director of the National Cancer Institute. An in-person reception follows the seminar.

Beth Gardner introduces spatial capture-recapture models for estimating wildlife population dynamics and movement. The seminar considers observations from camera traps and genetic identification using hair or scat, showing how the modeling framework can accommodate different sampling methods, time scales and movement processes. Gardner develops the Bayesian formulation through worked examples in R with NIMBLE, then discusses extensions and audience questions. The methods support estimates of demographic rates, spatial distributions and habitat relationships for conservation and management. The organizer explicitly schedules this occurrence at 15:00 Eastern time, rather than the series’ usual time.

To orchestrate complex behaviors in mammals, the cerebral cortex must continuously transmit its processing results to subcortical regions. While internal cortical processing relies on highly selective sparse codes, these descending cortical output streams employ an enigmatic dense code, characterized by high firing rates and low feature selectivity. This dense population code presents a profound paradox: how can downstream regions extract precise, cognitively relevant signals when most cortical output neurons can be active at any moment? We address this paradox by testing the hypothesis that cortex does not lose information when switching to a dense code. Instead, it utilizes a mechanism for sparse-to-dense coding transformations discovered by my laboratory: thalamocortical synapses target specifically the dendritic initiation zone for calcium action potentials (APs), which enables cortical output neurons to transmit multiple information streams simultaneously via a multiplexed 1-2-3 AP syntax. I will provide first evidence that this remarkable synaptic specificity and coding syntax generalize across long-range pathways. Information coupling via an anatomically and biophysically distinct dendritic nexus may hence be a ubiquitous mechanism for sparse-to-dense coding transformations in cortex. Dissecting these mechanistic origins of cortical output streams is only now possible due to a unique in vivo – in silico approach, perfected over two decades, that my laboratory developed for bridging the gaps between dendritic and population-level computations

Yixuan He (Arizona State University) considers graph neural networks for social, financial and biological networks in which edge signs and directions contain information needed for clustering and prediction. After an introduction to graph neural networks, the talk explains how signed and directed methods preserve relationships lost when every connection is treated as unsigned and undirected. The seminar then asks when a representation learned before the final task can transfer to a different graph or to a setting with few labels. Two theoretical perspectives address transfer across graph domains and the use of link prediction for linear community detection. TopoDIG and TopoSIGN combine encoders that preserve edge structure with persistent topological features, enabling pre-training and prompt-based adaptation on directed and signed networks.

Richard Huang investigates how DNA nanostructures deform under uneven hydrodynamic forces, a question relevant to drug delivery, vaccines and biosensors. Coarse-grained molecular dynamics and mechanical models first examine linear and circular DNA in extensional flow. Drag concentrates tension near the middle of linear duplexes, disrupting base pairs and causing overstretching. Deforming minicircles straighten along their sides while concentrating bending into opposing tips and localized kinks. Models based on DNA elasticity and hydrodynamic-force distributions explain these responses, then extend to wireframe DNA origami to study force transmission and how local structural transitions produce whole-particle deformation. The results inform structures designed for stability or controlled deformation in flow. Online via Zoom. Friday 2 October 2026, 12:00–13:00 EDT (America/New_York; UTC−4). Open the Zoom link on the official event page; the audience explicitly includes the public. Richard Huang is affiliated with MIT. Organized by MIT Department of Mathematics — Computational Research in Boston and Beyond Seminar.

Antonio Ocello tests the idea that heavy-tailed noise improves diffusion and flow-based generative models by matching heavy-tailed data and encouraging diverse samples. Replacing Gaussian noise also changes the estimation task. A combined theoretical and experimental study derives sampling-error bounds for representative heavy- and light-tailed diffusion models, finding that heavy-tailed noise makes statistical estimation harder and produces less favourable bounds. Experiments with synthetic and real data recover the predicted trade-off. The results question whether heavy-tailed initialization reliably improves exploration of rare regions. This is joint work with Hamza Cherkaoui and Hélène Halconruy. Online via Microsoft Teams. Friday 2 October 2026 at 15:30 CEST / 13:30 UTC / 14:30 BST (Europe/Paris). Follow the Microsoft Teams link beneath this occurrence on the seminar page; the public route offers browser or app access. Ocello is affiliated with ENSAE Paris. Organized by GAMEX — Generative AI Modeling for Extreme Events, with GLE²N and CIRCE support; the series welcomes scientific exchange beyond the network.

Srinivasan Keshav (University of Cambridge) presents an interface designed to help ecologists use AI for remote sensing despite unfamiliarity with embeddings and algorithms. The Tessera Embeddings Explorer lets practitioners privately explore a region of interest, create habitat maps and perform regressions using their domain expertise and ground-truth knowledge. The talk demonstrates the tool and explains the design principles and the software architecture that follows from them, connecting usable ecological workflows with AI representations. Keshav is the Robert Sansom Professor of Computer Science at Cambridge.

Davide Sgalaberna surveys scintillator detectors in current particle-physics experiments and research toward improved tracking and calorimetry. Achieving fine spatial resolution in a large active target traditionally requires segmentation and optical isolation, increasing fabrication complexity and readout-channel counts. The talk examines approaches that retain target mass while improving three-dimensional tracking: precision assemblies of small plastic scintillator cubes or fibres, additive manufacturing of optically isolated voxels inside monolithic blocks, optical separation in three dimensions, and tracking in opaque liquid scintillators. Developments in photosensors also make arrays of plenoptic cameras a prospect for imaging scintillator volumes with submillimetre tracking resolution, without segmentation or optical fibres. The discussion connects these concepts to the requirements of future detectors and experiments.

Fault-tolerant quantum computation must overcome complex control requirements and substantial error-correction overhead. This talk describes reconfigurable neutral-atom arrays in which optical tweezers coherently transport atoms, enabling any-to-any connectivity, high-fidelity programmable operations and mid-circuit processing in a zoned architecture. Parallel control, transversal operations and long-range connections support experiments ranging from precise quantum-scrambling simulations to a universal fault-tolerant processing architecture. Theoretical methods exploiting reconfigurable connectivity reduce error-correction overhead and suggest that useful large-scale computation could require as few as 10,000 atomic qubits. The discussion considers the prospects for realizing this approach in the near term.

Picower Institute Colloquium on the Brain and Cognition featuring Christopher Harvey, PhD, of Harvard University, held in Singleton Auditorium (46-3002) at MIT Building 46, 43 Vassar Street.

Alok Puranik (Jane Street) examines data mixing for large language models: allocating model capacity and computation among training sources. A small model’s preferred data mix may differ from that of a larger model, yet the cost of large-model training forces many decisions to depend on smaller experiments. Scaling laws can predict performance as size and computation increase only when trends remain stable or change predictably. The talk uses experiments from Puranik’s work and frontier laboratories to examine data-mix questions that violate these assumptions, explain why small-scale results can mislead, and explore better methods for choosing training data. His research at Jane Street concerns scaling laws for sequence models in trading.

Sahand Tabatabaei presents SQUINT, a sensing platform that combines molecular electron spins, sensitive mechanical detection and control of spin interactions. Molecular sensors can be chemically adjusted and positioned near targets, offering flexibility that defects fixed inside a solid host cannot provide. The work uses a modified XYXY decoupling sequence to reduce dipolar interactions despite uneven control fields. In a sample containing roughly 100 trityl radicals, the reported coherence time reaches about 400 microseconds. These longer-lived spins enable frequency-selective measurements of weak alternating magnetic fields and spectroscopy of nearby nuclear-spin ensembles. The seminar explores how molecular control and mechanical readout can bring quantum sensing closer to complex chemical targets.

Scott J. Russo examines how chronic psychosocial stress alters communication between the immune system and the brain in depression and anxiety. Human observations and mouse experiments connect persistent increases in circulating monocytes and inflammatory signals with stress-related illness. The talk describes stress-responsive neurons that project to bone marrow and regulate monocyte production, release and trafficking. It also considers how stress disrupts the blood–brain barrier, allowing peripheral inflammatory proteins to affect reward regions such as the nucleus accumbens. Together, these findings examine how peripheral immune cells act at the neurovascular interface to change brain circuits and behaviour, providing potential mechanisms relevant to treatment-resistant mood disorders. Online via Rutgers Brain Health Institute Zoom. Thursday 1 October 2026, 12:00–13:00 EDT (America/New_York; UTC−4). Open the organizer’s event page and follow its Zoom link; the meeting ID and passcode are supplied there. Hosted by Yong Kim as part of the BHI Plenary Seminar Series. This listing advertises the verified remote option.

Ali Kheirandish reviews how high-energy neutrinos are reshaping multimessenger astronomy and searches for new particle physics. IceCube established the astrophysical neutrino signal in 2013; a decade of observations has since revealed directional structure, with emission identified from nearby active galaxies and a smaller contribution from the Milky Way. The seminar examines these measurements, the emerging account of where cosmic neutrinos originate, and opportunities to test physics beyond the Standard Model through the neutrino sector.