Differential learning kinetics govern the transition from memorization to generalization during in-context learning.

Transformers exhibit in-context learning (ICL): the ability to use novel information presented in the context without additional weight updates. Recent work shows that ICL emerges when models are trained on a sufficiently diverse set of tasks and the transition from memorization to generalization is sharp with increasing task diversity. One interpretation is that a network's limited capacity to memorize favors generalization.

Distinct information conveyed to the olfactory bulb by feedforward input from the nose and feedback from the cortex.

Sensory systems are organized hierarchically, but feedback projections frequently disrupt this order. In the olfactory bulb (OB), cortical feedback projections numerically match sensory inputs. To unravel information carried by these two streams, we imaged the activity of olfactory sensory neurons (OSNs) and cortical axons in the mouse OB using calcium indicators, multiphoton microscopy, and diverse olfactory stimuli.

Sticky issues in turbulent transport.

We investigate the role of partial stickiness among particles or with a surface for turbulent transport. For the former case, we re-derive known results for the case of the compressible Kraichnan model by using a method based on bi-orthogonality for the expansion of the propagator in terms of left and right eigenvectors. In particular, we show that enforcing the constraints of orthogonality and normalization yields results that were previously obtained by a rigorous, yet possibly less intuitive method.

Adaptive algorithms for shaping behavior.

Dogs and laboratory mice are commonly trained to perform complex tasks by guiding them through a curriculum of simpler tasks ('shaping'). What are the principles behind effective shaping strategies? Here, we propose a machine learning framework for shaping animal behavior, where an autonomous teacher agent decides its student's task based on the student's transcript of successes and failures on previously assigned tasks. Using autonomous teachers that plan a curriculum in a common sequence learning task, we show that near-optimal shaping algorithms adaptively alternate between simpler and harder tasks to carefully balance reinforcement and extinction.

Inferring sparse structure in genotype-phenotype maps.

Correlation among multiple phenotypes across related individuals may reflect some pattern of shared genetic architecture: individual genetic loci affect multiple phenotypes (an effect known as pleiotropy), creating observable relationships between phenotypes. A natural hypothesis is that pleiotropic effects reflect a relatively small set of common "core" cellular processes: each genetic locus affects one or a few core processes, and these core processes in turn determine the observed phenotypes. Here, we propose a method to infer such structure in genotype-phenotype data.

Epistasis and evolution: recent advances and an outlook for prediction.

As organisms evolve, the effects of mutations change as a result of epistatic interactions with other mutations accumulated along the line of descent. This can lead to shifts in adaptability or robustness that ultimately shape subsequent evolution. Here, we review recent advances in measuring, modeling, and predicting epistasis along evolutionary trajectories, both in microbial cells and single proteins.

A reinforcement-based mechanism for discontinuous learning.

Problem-solving and reasoning involve mental exploration and navigation in sparse relational spaces. A physical analogue is spatial navigation in structured environments such as a network of burrows. Recent experiments with mice navigating a labyrinth show a sharp discontinuity during learning, corresponding to a distinct moment of "sudden insight" when mice figure out long, direct paths to the goal.

Outcomes of Allograft Medial Patellofemoral Ligament Reconstruction in Children and Adolescents with Hypermobility.

Introduction: Medial patellofemoral ligament (MPFL) reconstruction is used to treat patellofemoral instability either in isolation or in combination with other procedures. Use of allograft can preserve native tissue in children and can be advantageous in patients with connective tissue disorders, including ligamentous laxity. There is limited evidence regarding functional outcomes of allograft MPFL reconstruction in children and adolescents.

Alternation emerges as a multi-modal strategy for turbulent odor navigation.

Foraging mammals exhibit a familiar yet poorly characterized phenomenon, 'alternation', a pause to sniff in the air preceded by the animal rearing on its hind legs or raising its head. Rodents spontaneously alternate in the presence of airflow, suggesting that alternation serves an important role during plume-tracking. To test this hypothesis, we combine fully resolved simulations of turbulent odor transport and Bellman optimization methods for decision-making under partial observability.

A lexical approach for identifying behavioural action sequences.

Animals display characteristic behavioural patterns when performing a task, such as the spiraling of a soaring bird or the surge-and-cast of a male moth searching for a female. Identifying such recurring sequences occurring rarely in noisy behavioural data is key to understanding the behavioural response to a distributed stimulus in unrestrained animals. Existing models seek to describe the dynamics of behaviour or segment individual locomotor episodes rather than to identify the rare and transient sequences of locomotor episodes that make up the behavioural response.

Sector search strategies for odor trail tracking.

Ants, mice, and dogs often use surface-bound scent trails to establish navigation routes or to find food and mates, yet their tracking strategies remain poorly understood. Chemotaxis-based strategies cannot explain casting, a characteristic sequence of wide oscillations with increasing amplitude performed upon sustained loss of contact with the trail. We propose that tracking animals have an intrinsic, geometric notion of continuity, allowing them to exploit past contacts with the trail to form an estimate of where it is headed.

Global epistasis emerges from a generic model of a complex trait.

Epistasis between mutations can make adaptation contingent on evolutionary history. Yet despite widespread 'microscopic' epistasis between the mutations involved, microbial evolution experiments show consistent patterns of fitness increase between replicate lines. Recent work shows that this consistency is driven in part by global patterns of diminishing-returns and increasing-costs epistasis, which make mutations systematically less beneficial (or more deleterious) on fitter genetic backgrounds.

Coronavirus infection in hip fractures (CHIP) study.

Aims: Despite the COVID-19 pandemic, incidence of hip fracture has not changed. Evidence has shown increased mortality rates associated with COVID-19 infection. However, little is known about the outcomes of COVID-19 negative patients in a pandemic environment.

Antagonistic odor interactions in olfactory sensory neurons are widespread in freely breathing mice.

Odor landscapes contain complex blends of molecules that each activate unique, overlapping populations of olfactory sensory neurons (OSNs). Despite the presence of hundreds of OSN subtypes in many animals, the overlapping nature of odor inputs may lead to saturation of neural responses at the early stages of stimulus encoding. Information loss due to saturation could be mitigated by normalizing mechanisms such as antagonism at the level of receptor-ligand interactions, whose existence and prevalence remains uncertain.

Odorant Receptor Inhibition Is Fundamental to Odor Encoding.

Most natural odors are complex mixtures of volatile components, competing to bind odorant receptors (ORs) expressed in olfactory sensory neurons (OSNs) of the nose. To date, surprisingly little is known about how OR antagonism shapes neuronal representations in the detection layer of the olfactory system. Here, we investigated its prevalence, the degree to which it disrupts OR ensemble activity, and its conservation across phylogenetically related ORs.

Can the Surgical Approach to Total Knee Arthroplasty Influence Early Postoperative Outcomes? - A Comparative Study between Trivector and Medial Parapatellar Approaches.

Background: Trivector approach to total knee arthroplasty (TKA) is a quadriceps tendon sparing approach, whereas the medial parapatellar (MPP) approach involves making a longitudinal incision in quadriceps tendon. We postulated that quadriceps-sparing approach such as trivector should make postoperative rehabilitation easier and ultimately reduce the length of hospital stay.

Objectives: The aim of the study is to compare the early postoperative outcomes of the TKA performed through the trivector and the MPP approaches.

Novel Antegrade Approach to Transcatheter Aortic Valve Paravalvular Leak Closure.

Aortic paravalvular leak (PVL) is a known complication of TAVR. PVL closure using vascular occluder devices can be used, particularly in cases with annular calcification preventing adequate seal; however, delivery of equipment can be challenging in TAVR patients due to interaction with the valve stent. We describe a novel antegrade closure approach to treat transcatheter aortic PVL.

Receptor crosstalk improves concentration sensing of multiple ligands.

Cells need to reliably sense external ligand concentrations to achieve various biological functions such as chemotaxis or signaling. The molecular recognition of ligands by surface receptors is degenerate in many systems, leading to crosstalk between ligand-receptor pairs. Crosstalk is often thought of as a deviation from optimal specific recognition, as the binding of noncognate ligands can interfere with the detection of the receptor's cognate ligand, possibly leading to a false triggering of a downstream signaling pathway.

Outcomes of Intramedullary Nailing with Cerclage Wiring in Subtrochanteric Femoral Fractures.

Aims: The aim of this study was to compare the outcomes of closed reduction against open reduction with cerclage wires in patients with subtrochanteric fractures treated with intramedullary nailing (IMN).

Materials And Methods: We identified 141 patients who had an IMN over a 4-year period. They were classified into three groups based on fracture pattern and whether open or closed reduction was performed.

Demystifying excessively volatile human learning: A Bayesian persistent prior and a neural approximation.

Understanding how humans and animals learn about statistical regularities in stable and volatile environments, and utilize these regularities to make predictions and decisions, is an important problem in neuroscience and psychology. Using a Bayesian modeling framework, specifically the Dynamic Belief Model (DBM), it has previously been shown that humans tend to make the assumption that environmental statistics undergo abrupt, unsignaled changes, even when environmental statistics are actually stable. Because exact Bayesian inference in this setting, an example of switching state space models, is computationally intensive, a number of approximately Bayesian and heuristic algorithms have been proposed to account for learning/prediction in the brain.

Effect of percutaneous paravalvular leak closure on hemolysis.

Objective: To study the effect of percutaneous paravalvular leak closure on hemolysis.

Background: Although transcatheter PVL closure reduces heart failure and mortality in symptomatic patients with paravalvular leaks (PVL), little is known about its effect on hemolysis.

Methods: We retrospectively analyzed patients undergoing transcatheter mitral or aortic PVL closure (January 2005-December 2016) at Mayo Clinic.

Glider soaring via reinforcement learning in the field.

Soaring birds often rely on ascending thermal plumes (thermals) in the atmosphere as they search for prey or migrate across large distances. The landscape of convective currents is rugged and shifts on timescales of a few minutes as thermals constantly form, disintegrate or are transported away by the wind. How soaring birds find and navigate thermals within this complex landscape is unknown.

Antagonism in olfactory receptor neurons and its implications for the perception of odor mixtures.

Natural environments feature mixtures of odorants of diverse quantities, qualities and complexities. Olfactory receptor neurons (ORNs) are the first layer in the sensory pathway and transmit the olfactory signal to higher regions of the brain. Yet, the response of ORNs to mixtures is strongly non-additive, and exhibits antagonistic interactions among odorants.