Metabolic trade-offs in childhood: Exploring the relationship between language development and body growth.

During human childhood, brain development and body growth compete for limited metabolic resources, resulting in a trade-off where energy allocated to brain development can decrease as body growth accelerates. This preregistered study explores the relationship between language skills, serving as a proxy for brain development, and body mass index at three distinct developmental stages, representing different phases of body growth. Longitudinal data from 2002 children in the EDEN mother-child cohort were analyzed using structural equation modeling. Our findings reveal a compelling pattern of associations: girls with a delayed adiposity rebound, signaling slower growth rate, demonstrated better language proficiency at ages 5-6. Importantly, this correlation appears to be specific to language skills and does not extend to nonverbal cognitive abilities. Exploratory analyses show that early environmental factors contributing to enhanced cognitive development, such as higher parental socio-economic status and increased cognitive stimulation, are positively associated with both language skills and the timing of adiposity rebound in girls. Overall, our findings lend support to the existence of an energy allocation trade-off mechanism that appears to prioritize language function over body growth investment in girls. RESEARCH HIGHLIGHTS: The high energy demand of neurocognitive development leads to a trade-off in human children between brain growth and other biological functions, including body growth. Previous studies indicate that around age 5, when the brain energy consumption peaks, children typically experience a decrease in body mass known as 'adiposity rebound'. A delayed adiposity rebound, indicating slower growth may be associated with enhanced language abilities in children. Our preregistered study confirms this correlation in girls and further associates early cognitive stimulation with improved language skills and delayed adiposity rebound time.

Associations Between Early Life Adversity, Reproduction-Oriented Life Strategy, and Borderline Personality Disorder.

Importance: Borderline personality disorder (BPD) is often accompanied by a history of high-risk sexual behavior and somatic comorbidities. Yet, these features are most often considered in isolation and little is known about their underlying developmental pathways. Life history theory, a leading framework in evolutionary developmental biology, can help make sense of the wide range of behaviors and health issues found in BPD. Objective: To examine whether the emergence of BPD is associated with the prioritization of immediate reproductive goals over longer-term somatic maintenance goals, a life strategy that can be viewed as a developmental response to adverse early life experiences, providing rapid reproductive benefits despite costs to health and well-being. Design, Setting, and Participants: This study used cross-sectional data from the second wave of the National Epidemiologic Survey on Alcohol and Related Conditions in 2004-2005 (n = 34 653). Civilian, noninstitutionalized individuals in the US, 18 years or older, and those with and without a DSM-IV diagnosis of BPD were included. Analysis took place between August 2020 and June 2021. Main Outcomes and Measures: Structural equation models were used to examine whether early life adversity was associated with the likelihood of a BPD diagnosis, either directly or indirectly through a life strategy whereby individuals trade somatic maintenance for immediate reproduction. Results: Analyses were performed on a sample of 30 149 participants (females: 17 042 [52%]; mean [SE] age, 48.5 [0.09]; males: 12 747 [48%]; mean [SE] age, 47 [0.08]). Of these, 892 (2.7%) had a diagnosis of BPD and 29 257 (97.3%) did not have BPD. Mean early life adversity, metabolic disorder score, and body mass index were significantly higher among participants with a diagnosis of BPD. In an analysis adjusted for age, individuals with BPD reported having significantly more children than those without BPD (b =0.06; SE, 0.01; t = 4.09; P < .001). Having experienced greater levels of adversity in early life was significantly associated with a greater risk of being diagnosed with BPD later in life (direct relative risk = 0.268; SE, 0.067; P < .001). Importantly, this risk was further increased by 56.5% among respondents who prioritized short-term reproductive goals over somatic maintenance (indirect relative risk = 0.565; SE, 0.056; P < .001). Similar patterns of associations were found in male and female individuals. Conclusions and Relevance: The hypothesis of a reproduction/maintenance life history trade-off mediating the association between early life adversity and BPD helps make sense of the high dimensionality that characterizes the physiological and behavioral correlates of BPD. Additional studies are needed to confirm these results using longitudinal data.

Susceptibility of agency judgments to social influence.

The experience of agency refers to the phenomenal experience of being the causal source of one's own actions, and through them, the course of events in the outside world. This experience is crucial for the production of adaptive actions, and for the adequate communication of felt action control to peers. The present study examines the possibility that, on certain occasions and under specific internal and external constraints, people rely on explicit social information provided by their peers to revise their self-reports of perceived control, i.e., their judgment of agency. To test this hypothesis, we adapted a task based on an interactive computer game. We manipulated well-known sensorimotor agency cues related to action control, as well as social information communicated to participants by two advisors. We measured the contribution of social and non-social sources of information to agency judgments. We found that at the single-trial level, participants align their JoA with advisor feedback based on their own performance during the task, the type of feedback provided by advisors, and the interaction of this social feedback with the sensorimotor agency cues. At the same time, JoA alignment in previous trial also predicted participants' tendency to revise their JoA after social feedback. Overall, these results demonstrate that agency judgment is subject to social influence. This influence is the result of the integration of social and non-social information at the scale of a single judgment, while also being driven by repeated past interactions with peers.

The ecological roots of human susceptibility to social influence: a pre-registered study investigating the impact of early-life adversity.

There is considerable variability in the degree to which individuals rely on their peers to make decisions. Although theoretical models predict that environmental risks shift the cost-benefit trade-off associated with social information use, this idea has received little empirical support. Here we aim to test the effect of childhood environmental adversity on humans' susceptibility to follow others' opinion in the context of a standard face evaluation task. Results collected in a pilot study involving 121 adult participants tested online showed that susceptibility to social influence and childhood environmental adversity are positively associated. Computational analyses further confirmed that this effect is not explained by the fact that participants exposed to early adversity produce noisier decisions overall but that they are indeed more likely to follow the group's opinion. To test the robustness of these findings, a pre-registered direct replication using an optimal sample size was run. The results obtained from 262 participants in the pre-registered study did not reveal a significant association between childhood adversity and task performance but the meta-analysis ran on both the pilot and the pre-registered study replicated the initial finding. This work provides experimental evidence for an association between individuals' past ecology and their susceptibility to social influence.

Human susceptibility to social influence and its neural correlates are related to perceived vulnerability to extrinsic morbidity risks.

Humans considerably vary in the degree to which they rely on their peers to make decisions. Why? Theoretical models predict that environmental risks shift the cost-benefit trade-off associated with the exploitation of others' behaviours (public information), yet this idea has received little empirical support. Using computational analyses of behaviour and multivariate decoding of electroencephalographic activity, we test the hypothesis that perceived vulnerability to extrinsic morbidity risks impacts susceptibility to social influence, and investigate whether and how this covariation is reflected in the brain. Data collected from 261 participants tested online revealed that perceived vulnerability to extrinsic morbidity risks is positively associated with susceptibility to follow peers' opinion in the context of a standard face evaluation task. We found similar results on 17 participants tested in the laboratory, and showed that the sensitivity of EEG signals to public information correlates with the participants' degree of vulnerability. We further demonstrated that the combination of perceived vulnerability to extrinsic morbidity with decoding sensitivities better predicted social influence scores than each variable taken in isolation. These findings suggest that susceptibility to social influence is partly calibrated by perceived environmental risks, possibly via a tuning of neural mechanisms involved in the processing of public information.

TMS over posterior parietal cortex disrupts trans-saccadic visual stability.

BACKGROUND: Saccadic eye movements change the retinal location of visual objects, but we do not experience the visual world as constantly moving, we perceive it as seamless and stable. This visual stability may be achieved by an internal or efference copy of each saccade that, combined with the retinal information, allows the visual system to cancel out or ignore the self-caused retinal motion. OBJECTIVE: The current study investigated the underlying brain mechanisms responsible for visual stability in humans with online transcranial magnetic stimulation (TMS). METHODS: We used two classic tasks that measure efference copy: the double-step task and the in-flight displacement task. The double-step task requires subjects to make two memory-guided saccades, the second of which depends on an accurate internal copy of the first. The in-flight displacement task requires subjects to report the relative location of a (possibly displaced) target across a saccade. In separate experimental sessions, subjects participated in each task while we delivered online 3-pulse TMS over frontal eye fields (FEF), posterior parietal cortex, or vertex. TMS was contingent on saccade execution. RESULTS: Second saccades were not disrupted in the double-step task, but surprisingly, TMS over FEF modified the metrics of the ongoing saccade. Spatiotopic performance in the in-flight displacement task was altered following TMS over parietal cortex, but not FEF or vertex. CONCLUSION: These results suggest that TMS disrupted eye-centered position coding in the parietal cortex. Trans-saccadic correspondence, and visual stability, may therefore causally depend on parietal maps.

Neural coding of prior expectations in hierarchical intention inference.

The ability to infer other people's intentions is crucial for successful human social interactions. Such inference relies on an adaptive interplay of sensory evidence and prior expectations. Crucially, this interplay would also depend on the type of intention inferred, i.e., on how abstract the intention is. However, what neural mechanisms adjust the interplay of prior and sensory evidence to the abstractness of the intention remains conjecture. We addressed this question in two separate fMRI experiments, which exploited action scenes depicting different types of intentions (Superordinate vs. Basic; Social vs. Non-social), and manipulated both prior and sensory evidence. We found that participants increasingly relied on priors as sensory evidence became scarcer. Activity in the medial prefrontal cortex (mPFC) reflected this interplay between the two sources of information. Moreover, the more abstract the intention to infer (Superordinate > Basic, Social > Non-Social), the greater the modulation of backward connectivity between the mPFC and the temporo-parietal junction (TPJ), resulting in an increased influence of priors over the intention inference. These results suggest a critical role for the fronto-parietal network in adjusting the relative weight of prior and sensory evidence during hierarchical intention inference.

Reduced sensitivity to social priors during action prediction in adults with autism spectrum disorders.

An extensive amount of evidence has documented a diminished ability to predict and understand other people's action in individuals with autism spectrum disorders (ASD). Recently, two theoretical accounts, the "Hypo-priors" and the "Aberrant precision" hypotheses, have suggested that attenuated Bayesian priors or an imbalance of the precision ascribed to sensory evidence relative to prior expectations may be responsible for the atypical perceptual experience and difficulties with action understanding in ASD. In the present study, we aimed to directly investigate whether difficulties in the appreciation of others' intentions can be accounted for by abnormal interaction between these two types of information: (i) the sensory evidence conveyed by movement kinematics, and (ii) the observer's expectations, acquired from past experience or derived from prior knowledge. To test this hypothesis, we contrasted the ability to infer Non-Social and Social intentions in adults with and without ASD, using a series of tasks in which both sensory evidence and prior expectations were manipulated. The results showed that attenuated effect of prior expectations in ASD individuals does not result from a generalized impairment in mentalizing, but one confined to social intentions. Attenuated priors in the social domain predicted the severity of clinical symptoms in the area of social interaction. Importantly, however, we found that reduced priors in the social domain could be compensated by ASD through observational learning, i.e. through deriving statistical regularities from observed behaviours. This capacity to balance reduced social expectations by learning inversely correlated with the severity of repetitive and stereotyped behaviours. Collectively, these findings suggest that adults with ASD exhibit a disturbance in the inferential mechanism that integrates sensory evidence into prior beliefs to produce accurate inferences about other people's intentions.

Climate is not a good candidate to account for variations in aggression and violence across space and time.

We agree with Van Lange et al. that climate is likely to affect individuals' social behavior in many ways. However, we suspect that its impact on physiology and psychology is so remote that its predictive power disintegrates almost completely through the causal chain underlying aggression and violence.

Changing ideas about others' intentions: updating prior expectations tunes activity in the human motor system.

Predicting intentions from observing another agent's behaviours is often thought to depend on motor resonance - i.e., the motor system's response to a perceived movement by the activation of its stored motor counterpart, but observers might also rely on prior expectations, especially when actions take place in perceptually uncertain situations. Here we assessed motor resonance during an action prediction task using transcranial magnetic stimulation to probe corticospinal excitability (CSE) and report that experimentally-induced updates in observers' prior expectations modulate CSE when predictions are made under situations of perceptual uncertainty. We show that prior expectations are updated on the basis of both biomechanical and probabilistic prior information and that the magnitude of the CSE modulation observed across participants is explained by the magnitude of change in their prior expectations. These findings provide the first evidence that when observers predict others' intentions, motor resonance mechanisms adapt to changes in their prior expectations. We propose that this adaptive adjustment might reflect a regulatory control mechanism that shares some similarities with that observed during action selection. Such a mechanism could help arbitrate the competition between biomechanical and probabilistic prior information when appropriate for prediction.

Perturbing the action observation network during perception and categorization of actions' goals and grips: state-dependency and virtual lesion TMS effects.

Watching others grasping and using objects activates an action observation network (AON), including inferior frontal (IFC), anterior intraparietal (AIP), and somatosensory cortices (S1). Yet, causal evidence of the differential involvement of such AON sensorimotor nodes in representing high- and low-level action components (i.e., end-goals and grip type) is meager. To address this issue, we used transcranial magnetic stimulation-adaptation (TMS-A) during 2 novel action perception tasks. Participants were shown adapting movies displaying a demonstrator performing goal-directed actions with a tool, using either power or precision grips. They were then asked to match the end-goal (Goal-recognition task) or the grip (Grip-recognition task) of actions shown in test pictures to the adapting movies. TMS was administered over IFC, AIP, or S1 during presentation of test pictures. Virtual lesion-like effects were found in the Grip-recognition task where IFC stimulation induced a general performance decrease, suggesting a critical role of IFC in perceiving grips. In the Goal-recognition task, IFC and S1 stimulation differently affected the processing of "adapted" and "nonadapted" goals. These "state-dependent" effects suggest that the overall goal of seen actions is encoded into functionally distinct and spatially overlapping neural populations in IFC-S1 and such encoding is critical for recognizing and understanding end-goals.

Abstract and concrete phrases processing differentially modulates cortico-spinal excitability.

An important challenge of embodied theories is to explain the comprehension of abstract sentences. The aim of the present study was to scrutinize the role of the motor cortex in this process. We developed a new paradigm to study the abstract-concrete dimension by combining concrete (i.e., action-related) and abstract (i.e., non-action-related) verbs with nouns of graspable and non-graspable objects. Using these verb-noun combinations we performed a Transcranial Magnetic Stimulation (TMS) on the left primary motor cortex while participants performed a sentence sensibility task. Single-TMS pulses were delivered 250ms after verb or noun presentation in each of four combinations of abstract and concrete verbs and nouns. To evaluate cortico-spinal excitability we registered the electromyographic activity of the right first dorsal interosseous muscle. As to verb-noun integration, analysis of motor evoked potentials (MEPs) after TMS pulse during noun presentation revealed greater peak-to-peak amplitude in phrases containing abstract rather than concrete verbs. Response times were also collected and showed that compatible (Concrete-Concrete and Abstract-Abstract) combinations were processed faster than mixed ones; moreover in combinations containing concrete verbs, participants were faster when the pulse was delivered on the first word (verb) than on the second one (noun). Results support previous findings showing early activation of hand-related areas after concrete verbs processing. The prolonged or delayed activation of the same areas by abstract verbs will be discussed in the framework of recent embodied theories based on multiple types of representation, particularly theories emphasizing the role of different acquisition mechanisms for concrete and abstract words (Borghi and Cimatti, 2009,2012).

Can object affordances impact on human social learning of tool use?

The author describes "higher" and "uniquely human" sociocognitive skills that he argues as being necessary for tool use. We propose that those skills could be based on simpler detection systems humans could share with other animal tool users. More specifically, we discuss the impact of object affordances on the understanding and the social learning of tool use.

Object affordances tune observers' prior expectations about tool-use behaviors.

Learning about the function and use of tools through observation requires the ability to exploit one's own knowledge derived from past experience. It also depends on the detection of low-level local cues that are rooted in the tool's perceptual properties. Best known as 'affordances', these cues generate biomechanical priors that constrain the number of possible motor acts that are likely to be performed on tools. The contribution of these biomechanical priors to the learning of tool-use behaviors is well supported. However, it is not yet clear if, and how, affordances interact with higher-order expectations that are generated from past experience--i.e. probabilistic exposure--to enable observational learning of tool use. To address this question we designed an action observation task in which participants were required to infer, under various conditions of visual uncertainty, the intentions of a demonstrator performing tool-use behaviors. Both the probability of observing the demonstrator achieving a particular tool function and the biomechanical optimality of the observed movement were varied. We demonstrate that biomechanical priors modulate the extent to which participants' predictions are influenced by probabilistically-induced prior expectations. Biomechanical and probabilistic priors have a cumulative effect when they 'converge' (in the case of a probabilistic bias assigned to optimal behaviors), or a mutually inhibitory effect when they actively 'diverge' (in the case of probabilistic bias assigned to suboptimal behaviors).