Primary visual cortex straightens natural video trajectories

Many sensory-driven behaviors rely on predictions about future states of the environment. Visual input typically evolves along complex temporal trajectories that are difficult to extrapolate. We test the hypothesis that spatial processing mechanisms in the early visual system facilitate prediction by constructing neural representations that follow straighter temporal trajectories. We recorded V1 population activity in anesthetized macaques while presenting static frames taken from brief video clips, and developed a procedure to measure the curvature of the associated neural population trajectory. We found that V1 populations straighten naturally occurring image sequences, but entangle artificial sequences that contain unnatural temporal transformations. We show that these effects arise in part from computational mechanisms that underlie the stimulus selectivity of V1 cells. Together, our findings reveal that the early visual system uses a set of specialized computations to build representations that can support prediction in the natural environment.

Elucidating the neural mechanisms of Learning-to-Learn

Learning-to-learn, a progressive acceleration of learning while solving a series of similar problems, represents a core process of knowledge acquisition that draws attention in both neuroscience and artificial intelligence. To investigate its underlying brain mechanism, we trained a recurrent neural network model on arbitrary sensorimotor mappings. The network displayed an exponential speedup in learning. The neural substrate of a schema emerges within a low-dimensional subspace of population activity. Its reuse in new problems facilitates learning by limiting connection weight changes. Since the population trajectory of a recurrent network produces behavior, learning is determined by the vector field changes. We propose a novel analysis of weight-driven vector field changes, which showed that novel stimuli in new problems can distort the schema representation. Weight changes eliminate such distortions and improve the invariance of the reused representations in future learning. The accumulation of such weight changes across problems underlies the learning-to-learn dynamics.

Residual dynamics resolves recurrent contributions to neural computation

Relating neural activity to behavior requires an understanding of how neural computations arise from the coordinated dynamics of distributed, recurrently connected neural populations. However, inferring the nature of recurrent dynamics from partial recordings of a neural circuit presents significant challenges. Here, we show that some of these challenges can be overcome by a fine-grained analysis of the dynamics of neural residuals, i.e. trial-by-trial variability around the mean neural population trajectory for a given task condition. Residual dynamics in macaque pre-frontal cortex (PFC) in a saccade-based perceptual decision-making task reveals recurrent dynamics that is time-dependent, but consistently stable, and implies that pronounced rotational structure in PFC trajectories during saccades are driven by inputs from upstream areas. The properties of residual dynamics restrict the possible contributions of PFC to decision-making and saccade generation, and suggest a path towards fully characterizing distributed neural computations with large-scale neural recordings and targeted causal perturbations.

Construction of Biophysical Indicators for the Catalan Economy: Building a New Conceptual Framework

The main objective of this work is to create an environmental vision of the Catalan economy based on various indicators. To do this, we started from the fundamental idea of obtaining new metrics to measure impacts on the economy. The methodology used is focused on the systematization of descriptive statistics and econometric review. In this sense, GDP and GDP per capita are valued as chrematistic units, and biophysical variables are incorporated. For the period 2000–2016, the figures for energy consumption, CO2 emissions, energy intensity of the economy and water consumption were collected. In addition, demographic evolution and the Gini index were also ordered as factors that contribute to explaining not only population trajectory but also some of the social factors. Greater technological efficiency in regard to environmental aspects is intuited as sensitive to the economic cycle. The study is novel in the panorama of the regional economy of Spain, by incorporating biophysical variables to the applied economic analysis.

Interculturalism, multiculturalism and Italianness: The case of Italy

Until the 1970s, Italy’s population trajectory had demonstrated a clear propensity to be an emigrating nation. Over its almost 150-year history, it had witnessed four major phases of outward migration which had defined this country and created large diasporas across the globe. However, major changes began occurring to this demographic trajectory. It saw the unexpected arrival of large numbers of migrants from mostly poorer nations which it only reluctantly acknowledged. But, Italy was both unprepared and unconvinced to respond to this new phenomenon of incoming migration. Even though many of its European neighbours began to engage with this new and wider multicultural paradigm emerging in the 1980s, this multicultural approach never took hold in Italy. At the same time segments of the Italian education system were obliged to tackle recently arrived large numbers of migrants and their children requiring integrated models of education. While the political elites sought to remain immobile with large numbers of incoming immigrants, schools and educational institutions had little choice. Unfortunately, as this paper will demonstrate, this approach was mostly limited to the area of education. Although Interculturalism received a boost from its European Union promotion in 2008, it remained largely an activity exercised within the domain of public education. Fundamentally multiculturalism, like interculturalism were never officially embraced in Italy. While some sectors of society constructively engaged with interculturalism arguably as a different and more developed idea than multiculturalism, Italy and its policymakers continue to avoid engagement with migrant integration models whatever they be.

Mouse eradication is required to prevent local extinction of an endangered seabird on an oceanic island

Petrels (Procellariidae) are a highly diverse family of seabirds, many of which are globally threatened due to the impact of invasive species on breeding populations. While predation by invasive cats and rats has led to the extinction of petrel populations, the impact of invasive house mice Mus musculus is slower and less well documented. However, mice impact small burrow-nesting species such as MacGillivray’s prion Pachyptila macgillivrayi, a species classified as endangered because it has been extirpated on islands in the Indian Ocean by introduced rodents. We use historic abundance data and demographic monitoring data from 2014 to 2020 to predict the population trajectory of MacGillivray’s prion on Gough Island with and without a mouse eradication using a stochastic integrated population model. Given very low annual breeding success (0.01 fledglings per breeding pair in ‘poor’ years (83%) or 0.38 in ‘good’ years (17%), n = 320 nests over 6 years) mainly due to mouse predation, our model predicted that the population collapsed from ~3.5 million pairs in 1956 to an estimated 175,000 pairs in 2020 despite reasonably high adult survival probability (ϕ = 0.901). Based on these parameters, the population is predicted to decline at a rate of 9% per year over the next 36 years without a mouse eradication, with a 31% probability that by 2057 the MacGillivray’ prion population would become extremely vulnerable to extinction. Our models predict population stability (λ = 1.01) and a lower extinction risk (<10%) if mouse eradication on Gough Island restores annual breeding success to 0.519, which is in line with that of closely-related species on predator-free islands. This study demonstrates the devastating impacts that introduced house mice can have on small burrowing petrels and highlights the urgency to eradicate invasive mammals from oceanic islands.

CITIES THAT ARE LOSING INHABITANTS: AN ANALYSIS OF THE BRAZILIAN REALITY

Purpose: This article identifies the Brazilian cities that showed urban decline in the period between 1970 and 2010 based on the country's official census conducted by the IBGE (Brazilian Institute of Geography and Statistics). Based on this identification, analysis of the behaviors presented by the cities with population loss allows separate them according to the two theories that explain the loss of population: life cycle and persistent decline. Methodology: The article compares the Brazilian situation with countries from other continents, namely Europe, which also showed population decline in the cities. Findings: The results show a diversity of situations, whereby the population decline of cities is not a generalized phenomenon nor inevitable. Implication: This analysis allows the discussion about whether the loss of inhabitants in some cities is an inevitable part of a country's development process in the sense that as countries increase their development indices also increases the number of cities with population loss. Originality: This paper provides a comprehensive portrait of the lost of inhabitants in the Brazilian cities. The article is the first to analyze the population trajectory of all Brazilian cities, covering a period of four decades.

Population status and demographics of Lake Sturgeon in the Bad and White rivers, Wisconsin

Lake Sturgeon Acipenser fulvescens rehabilitation efforts in Lake Superior are guided by a rehabilitation plan that sets goals and criteria for a self-sustaining population, including a minimum of 1,500 mature adults, roughly equal sex ratio, and annual exploitation rates &lt; 5%. The Bad and White rivers, Wisconsin host a genetically unique Lake Sturgeon population that is utilized by state-licensed recreational anglers and tribal subsistence fishers. Our objectives were to 1) determine if the Bad River population meets rehabilitation plan targets for a self-sustaining population, 2) assess harvest of Lake Sturgeon by recreational anglers and tribal subsistence fishers for compatibility with rehabilitation goals, 3) determine population trajectory from annual spawning runs, and 4) describe population demographics given the unique physical features of Lake Superior. We sampled Lake Sturgeon in the Bad and White rivers with gill nets over a 17-y period (2001 to 2017). The observed sex ratio in spawning runs was 2.2:1 (male : female), but calculated at 1.6:1 for the entire adult population on the basis of abundance estimates. Weight–length relationships converted to a standardized modified form factor indicated lower condition and possibly lower female fecundity compared with other large North American populations. Annual spawning run size estimates over time indicated that the population trajectory was stable to slightly increasing, and during 2016 was 739 and 241 individuals in the Bad and White rivers, respectively. Total population size (including nonspawners) exceeded 1,500 individuals, which met Lake Superior rehabilitation criteria for a self-sustaining population. Estimates of 1,426 males and 882 females were considered conservative because 472 unknown-sex fish could not be accounted for in return time and abundance models. Spawning return times were 2 or 3 y for males and 4 to 6 y for females, longer than many other populations. Exploitation by recreational anglers and tribal subsistence fishers was 1.3% or lower and met the rehabilitation plan target of &lt; 5%, but we recommend exploitation not exceed 3.1% to maintain a self-sustaining population. These findings help gauge rehabilitation progress in Lake Superior and better describe the demographics of a remnant self-sustaining Lake Sturgeon population in Lake Superior.

Neural trajectories in the supplementary motor area and primary motor cortex exhibit distinct geometries, compatible with different classes of computation

The supplementary motor area (SMA) is believed to contribute to higher-order aspects of motor control. To examine this contribution, we employed a novel cycling task and leveraged an emerging strategy: testing whether population trajectories possess properties necessary for a hypothesized class of computations. We found that, at the single-neuron level, SMA exhibited multiple response features absent in M1. We hypothesized that these diverse features might contribute, at the population level, to avoidance of ‘population trajectory divergence’ – ensuring that two trajectories never followed the same path before separating. Trajectory divergence was indeed avoided in SMA but not in M1. Network simulations confirmed that low trajectory divergence is necessary when guidance of future action depends upon internally tracking contextual factors. Furthermore, the empirical trajectory geometry – helical in SMA versus elliptical in M1 – was naturally reproduced by networks that did, versus did not, internally track context.