Alexandre Zénon

Ecovillages are collective experiments in maintaining wellbeing within planetary limits, testing whether human flourishing can be maintained while material throughput is reduced. Drawing on a critical narrative review of intentional communities, ecological economics, commons governance, and self-determination theory, we propose a three- dimension, two-layer framework joining ecological limits, wellbeing, and the propagation dynamics of social innovations. The outcome layer includes five elements across three dimensions: critical natural capital and biophysical flows (ecological), material sufficiency and eudaimonic wellbeing (wellbeing), and transformative effect (transformative), an outward axis specific to social innovations. The lever layer includes three transversal levers: a sufficiency economy that drives throughput reduction, a commons governance built on Ostrom's design principles, and a propagation infrastructure that carries practices beyond the host site. Empirically, ecovillages deliver 35 to 80% footprint reductions and achieve partial closure of nutrient cycles. They meet a decent material floor through commons-based provisioning while sustaining or improving wellbeing. They propagate practices via transmission, replication, partnerships, and political influence. Four structural challenges constrain systemic contribution: limited actual impact on ecological, host- territory, and cultural dimensions; dependence on the mainstream provisioning system; barriers to scale (demanding resident profiles, high attrition); and social selection. We argue that ecovillages are best understood as generative laboratories of transposable knowledge and living alternatives that act as vectors of cultural changes. We propose an agenda for a wider community-based transition, associating multi-scale architectures with supportive economic models, facilitative institutions, and a deliberate research program. We situate this Northern articulation within a wider pluriverse of place-based sustainability projects, of which ecovillages are one strand among many.

Haueis and Colaço argue that metabolic considerations should constrain and generate cognitive models. Research in cognitive fatigue provides a test case. Passive fatigue induction reveals specific representational degradation that points to local rather than global metabolic mechanisms, pruning potential models. We argue that local aerobic glycolysis offers a coherent, testable generative account of these findings.

The assumption that the brain relies on Bayesian inference has been successful in accounting for many behavioural and neurophysiological observations, but the dependence on such a mechanism in arithmetic remains unknown. Bayesian inference implies the representation of uncertainty and reliance on prior beliefs. In arithmetic problem-solving, it would consist of refining priors over the response range as the system progressively integrates information conveyed by the operands. To test this hypothesis, we designed three experiments in which participants computed the sum of two numbers presented sequentially through headphones. The first operand was either highly informative and contributed to narrowing down the response range or poorly informative and conveyed little information about plausible responses. Throughout all experiments, pupil-related arousal signalled the information gain associated with the first operand, indicating that participants updated the probability distribution of responses upon hearing that first stimulus. Moreover, when participants received more informative operands and when their pupils dilated more during this presentation, they were also faster to respond, indicating that greater initial information processing facilitated quicker problem-solving. These findings show that Bayesian inference is central to arithmetic problem-solving and that information gains consequent to the integration of the operands can be tracked over time through pupillometry.

From a behavioral and neuronal perspective, observational and physical practice conditions have been theorized to be equivalent during motor task learning. However, some paradigms can challenge such a functional equivalence hypothesis. The perception of difficulties experienced by others may play a role in observational learning by allowing learners to partially distance themselves from these episodes, thereby limiting their impact on learning. In contrast, during physical practice, performance difficulties are directly experienced, which may constrain such distancing mechanisms. Indeed, an observer watching a model that uses a wrong physical strategy can ignore erroneous trials in order to preserve action encoding. The main goal of the present study was to prevent such observer avoidance and to test the cognitive and neuronal functional equivalence between the physical and observational practice groups. During this experiment, both groups learned two motor sequences. Only one sequence was repeatedly interrupted to perturb encoding. Behavioral results revealed that both groups were equally negatively impacted by such interruptions. Together, these findings suggest that while physical and observational practice can lead to comparable behavioral outcomes under strong disruption, they rely on partially distinct neural strategies. Physical practice predominantly engages motor and striato-cerebellar feedback loops, whereas observational learning relies more strongly on fronto-cerebellar and episodic memory networks, highlighting a context-dependent functional equivalence between learning modalities.

Apathy is marked by disruptions in effort-based decision-making for rewards and alterations in fronto–basal ganglia (BG) circuits. While changes in primary motor cortex (M1) activity during effort and reward valuation have been reported, prior work on apathy and effort-based decision-making has overlooked the connections between fronto–BG structures and M1. Here, we addressed this gap by investigating structural and effective connectivity within fronto-M1, fronto-BG-M1, and intra-M1 circuits in 45 healthy participants using tractography and paired-pulse transcranial magnetic stimulation. These measures were related to apathy scores and computational parameters of effort and reward valuation modelled from decision-making behavior. Apathy scores were associated with both structural and effective connectivity in orbitofrontal cortex-originating circuits. Additionally, effort and reward valuation were preferentially linked to supplementary motor area-related circuits and intra-M1 GABAergic circuits, respectively. These findings reveal dissociable circuit-level contributions to different dimensions of motivated behavior and identify potential neuromodulation targets for treating apathy.

1. Summary: Cognitive cost plays a crucial role in determining action choices and task engagement. We have proposed that cognitive cost relates to the amount of Bayesian inference required, quantified using relative entropy. In continuous tasks, such as visuomotor tracking, this demand can be estimated using transfer entropy (TE), which accounts for the information transferred from input to output variables. This study aimed to test experimentally the relationship between TE and markers of cognitive cost. We designed a continuous tracking task, manipulating target speed, predictability, and response lag. The effects of task variables on performance, subjective effort and pupil-linked arousal were assessed using Bayesian mixed models. We disentangled the effect of TE from that of other correlated variables (predictability, acceleration, spatial error), by using model comparison and mediation models. Results showed that TE was mostly affected by target predictability and impacted significantly on subjective effort and pupil response. While the variations of pupillary response induced by task conditions were accounted for by TE only, subjective effort was only partially predicted by TE, and depended also on target predictability. These findings suggest that the cognitive demand of motor control tasks can be quantified using TE, which relates to both subjective effort and pupillary response. However, the multifaceted nature of effort in motor tasks and the limitations of subjective measures highlight the need for more nuanced tools to isolate mental and physical effort.

The locus coeruleus-norepinephrine (LC-NE) system is a well-established regulator of behavior, yet its precise role remains unclear. Animal studies predominantly support a “gain” hypothesis, suggesting that the LC-NE system enhances sensory processing, while human studies have proposed an alternative “urgency” hypothesis, postulating that LC-NE primarily accelerates responses. To address this discrepancy, we administered transcutaneous vagus nerve stimulation (tVNS) in two experiments involving 43 participants. In the first experiment, we showed that 4-second tVNS trains reliably induced greater pupil dilation compared to SHAM condition, indicating increased LC-NE activity. In the second experiment, we applied tVNS during a random dot motion task to assess its impact on perceptual decision-making. Notably, tVNS improved accuracy without affecting reaction times, which appears inconsistent with the “urgency” hypothesis. Drift-diffusion model analyses further supported the “gain” hypothesis, revealing that tVNS increased the drift rate, indicative of enhanced evidence accumulation. Accuracy and drift-rate improvements were especially pronounced following errors and in less proficient participants, who otherwise exhibited post-error declines in these measures under SHAM condition. Our findings suggest that the influence of the LC-NE system adapts to task demands, becoming especially beneficial in challenging contexts. Overall, this study underscores the potential of tVNS as a non-invasive tool to investigate the causal role of the LC-NE system in human behavior.

SUMMARY: Apathy is a syndrome characterized by a disruption in effort-reward decision-making, accompanied by structural and functional changes in a related fronto-basal ganglia (BG) network. While activity changes in the primary motor cortex (M1) during effort and reward valuation have been repeatedly observed, previous work on apathy has largely overlooked the connections between the fronto-BG network and M1, potentially missing key circuits in the apathy network. This study addresses this gap by investigating structural and effective connectivity in fronto-M1, fronto-BG-M1, and intra-M1 circuits in relation to apathy in 45 healthy subjects. Behavior was assessed using a battery of apathy-related questionnaires and computational modeling of effort and reward valuation in a decision-making task. Fronto-motor circuits were examined through a combination of MRI-derived tractography and paired-pulse transcranial magnetic stimulation, which probed structural and effective connectivity, respectively. The data reveal that apathy scores are associated with both structural and effective connectivity in fronto-M1 and fronto-BG-M1 circuits. Circuits originating from the supplementary motor area primarily index effort valuation, while connectivity in intra-M1 GABAergic circuits correlates exclusively with reward valuation. These findings suggest that distinct fronto-motor circuits are linked to different dimensions of motivated behavior and may constitute specific neuromodulation targets for patients suffering from apathy.

Cognitive fatigue is defined by a reduced capacity to perform mental tasks. Despite its pervasiveness, the underlying neural mechanisms remain elusive. Specifically, it is unclear whether prolonged effort affects performance through alterations in over-worked task-relevant neuronal assemblies. Our paradigm based on repeated passive visual stimulation discerns fatigue effects from the influence of motivation, skill and boredom. We induced performance loss and observed parallel alterations in the neural blueprint of the task, by mirroring behavioral performance with multivariate neuroimaging techniques (MVPA) that afford a subject-specific approach. Crucially, functional areas that responded the most to repeated stimulation were also the most affected. Finally, univariate analysis revealed clusters displaying significant disruption within the extrastriate visual cortex. In sum, here we show that repeated stimulation impacts the implicated brain areas’ activity and causes tangible behavioral repercussions, providing evidence that cognitive fatigue can result from local, functional, disruptions in the neural signal induced by protracted recruitment.