Physical modeling of embryonic transcriptomes identifies collective modes of gene expression.

Starting from one totipotent cell, complex multicellular organisms form through a series of differentiation and morphogenetic events, culminating in a multitude of cell types arranged in a functional and intricate spatial pattern. To do so, cells coordinate with each other, resulting in dynamics which follow a precise developmental trajectory, constraining the space of possible embryo-to-embryo variation. Using recent single-cell sequencing data of early ascidian embryos, we leverage natural variation together with modeling and inference techniques from statistical physics to investigate development at the level of a complete interconnected embryo - an embryonic transcriptome. After developing a robust and biophysically motivated approach to identifying distinct transcriptomic states or cell types, a statistical analysis reveals correlations within embryos and across cell types demonstrating the presence of collective variation. From these intra-embryo correlations, we infer minimal networks of cell-cell interactions, which reveal the collective modes of gene expression. Our work demonstrates how the existence and nature of spatial interactions along with the collective modes of expression that they give rise to can be inferred from single-cell gene expression measurements, opening up a wider range of biological questions that can be addressed using sequencing-based modalities.

Age-related changes in how 5- to 8-year-old children use and execute finger-based strategies in arithmetic.

To determine how young children use and execute finger-based strategies, 5- to 8-year-olds were asked to solve simple addition problems under a choice condition (i.e., they could choose finger-based or non-finger strategies on each problem) and under two no-choice conditions (one in which they needed to use finger-based strategies on all problems and one in which they could not use finger-based strategies). Results showed that children (a) used both finger-based and non-finger strategies to solve simple addition problems in all age groups, (b) used fingers less and less often as they grew older, especially while solving smaller problems, (c) calibrated their use of finger-based strategies to both problem features and strategy performance, and (d) improved efficiency of both finger-based and non-finger strategy execution. Moreover, (e) strategy performance was the best predictor of strategy selection in all age groups, and (f) when they had the possibility to use fingers, children of all age groups obtained better performance relative to when they could not use fingers, especially on larger problems.

France needs a chief science adviser.

France is at a crossroads, facing environmental and social challenges that are profoundly altering its society. Yet, the French government keeps prioritizing short-term political gains over long-term evidence-based planning for major transitions that France, like most countries, will undergo over the next 20 years. There is an urgent need for France to implement long-term science-informed policy-making.

Are There Age-Related Differences in Effects of Positive and Negative Emotions in Arithmetic?

We investigated effects of emotions on arithmetic problem-solving and age-related differences in these effects. Young and older adults verified addition problems displayed superimposed on emotionally negative, positive, or neutral pictures. Participants obtained poorer performance in emotion than in neutral conditions, with stronger interference by negative than positive emotions. Also, participants were more impaired by negative emotions while solving true problems than false problems, whereas they were influenced by positive emotions similarly on true and false problems. Interestingly, effects of both positive and negative emotions were comparable in young and older adults. These findings have important implications for further understanding how negative and positive emotions influence arithmetic problem-solving.

The influence of irrelevant emotionally negative stimuli on early and late retrospective metacognitive judgements.

It is well established that negative emotions influence a range of cognitive processes. How these emotions influence the metacognitive judgement individuals make about their own performance and whether this influence is similar depending on the conditions under which metacognition is assessed, however, is far less understood. The primary aim of this study was to determine whether exposure to emotional stimuli could influence metacognitive judgements made under short or long time constraints. A total sample of 144 young adults (aged 18-35 years) was recruited and asked to complete an arithmetic strategy selection task under emotional or neutral condition. Following each strategy selection trial, participants also provided a retrospective confidence judgement (RCJ). Both strategy selection and RCJ were collected under short or long time constraints (1,500 vs. 2,500 ms for strategy selection and 800 vs. 1,500 ms for RCJ). In addition to replicating previous findings showing lower rates of better strategy selection under negative emotions compared with neutral condition, an effect of negative stimuli on the accuracy of participants' confidence judgements was found, but only if participants had a short time limit to make their second-level evaluation. Such findings are consistent with the hypothesis that exposure to emotional stimuli disturbs early, but not late metacognitive processes and have important implications to further our understanding of the role of emotions on metacognition.

Aging, emotion, and cognition: The role of strategies.

In three experiments, I examined the role of emotions in arithmetic and investigated how this role changes with aging. I adopted a strategy approach and examined strategic aspects of participants' performance under emotionally neutral and negative conditions. The data showed that negative emotions led participants to (a) use fewer strategies and change how often they used each available strategy (Experiment 1), (b) select the better strategy on each problem less often while solving both easier and harder problems (Experiment 2), and (c) obtain poorer performance (Experiments 1 and 3), even when strategy repertoire, distribution, and selection were controlled. Regarding age-related differences, I found that negative emotions (a) influenced efficiency of strategy execution less strongly in older adults than in young adults, (b) affected young adults' strategy repertoire but not older adults', (c) changed strategy distributions more strongly in young than in older adults, and (d) influenced strategy selection to the same extent in both age groups. These effects of emotions on strategy repertoire, distribution, execution, and selection, and age-related differences in these effects have important implications for explaining how emotions influence the mechanisms underlying task performance and to improve our understanding of how influence of emotions on cognition changes during aging. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

How Distracting Events Influence Young and Older adults' Arithmetic Performance?

In this study, I investigated the role of distraction on arithmetic performance and whether this role changes with aging during adulthood. Young and older adults were asked to verify one-digit addition problems (Expt. 1) or to estimate the results of two-digit multiplication problems (Expt. 2). In both experiments, true and false simple problems (Expt. 1) or easier and harder complex problems (Expt. 2) were displayed superimposed or not on irrelevant, emotionally neutral pictures (e.g. mushrooms). In both simple and complex arithmetic, young and older adults obtained poorer arithmetic performance under distraction relative to no-distraction conditions. Most interesting, deleterious effects of irrelevant stimuli on arithmetic performance were larger in older than in young adults. Moreover, magnitude of distraction effects increased with longer solution latencies in young (but not in older) adults while solving complex arithmetic problems. These findings have important implications for furthering our understanding of the role of distraction on cognitive performance in general, and arithmetic performance in particular, as well as age-related differences in this role.

How negative emotions affect young and older adults' numerosity estimation performance.

In this study, we investigated the influence of negative emotions on numerosity estimation and whether this influence changes with aging during adulthood. Young and older adults were asked to estimate and compare the numerosity of collections of elements (cars or dots) with a two-digit number. Collections of elements were preceded by emotionally neutral (e.g., mushrooms) or emotionally negative (e.g., a corpse) pictures. Stimuli were easier (i.e., small-ratio) or harder (i.e., large-ratio) items. Young and older participants obtained similar numerosity estimation performance. Interestingly, participants were less accurate under negative emotions than under neutral emotions when they estimated numerosity of collections of abstract elements (i.e., dots). In contrast, participants improved their performance under negative emotions while estimating collections of non-abstract, daily-life elements (i.e., cars). These findings have important implications for furthering our understanding of the role of negative emotions in numerosity estimation and age-related differences therein.

How do distracting events influence children's arithmetic performance?

To understand how distraction influences children's arithmetic performance, we examined effects of irrelevant sounds on children's performance while they solve arithmetic problems. Third and fifth graders were asked to verify true/false, one-digit addition problems (e.g., 9 + 4 = 12. True? False?) under silence and sound conditions. The sounds began when the problems started to appear on the screen (Experiment 1; N = 76) or slightly after (Experiment 2; N = 92) and continued until participants responded. The results showed that (a) children solved arithmetic problems more quickly in the sound condition than in the silence condition when the sounds started with problem display (phasic arousal effects); (b) children were slower on the arithmetic problem verification task when the sounds was played slightly after the problems started to appear on the screen (distraction effects); (c) phasic arousal effects were found only in third graders, whereas distraction effects were found in both grades, although their magnitudes were smaller in fifth graders; (d) distraction effects increased with increasing latencies in third graders but did not change across the entire latency distribution in fifth graders; and (e) distraction effects on current trials were smaller after sound trials than after silence trials in both age groups (sequential modulations of distraction effects). These findings have important implications for furthering our understanding of effects of irrelevant sounds on arithmetic performance as well as cognitive processes involved in children's arithmetic.

Emotions and arithmetic in children.

How do negative emotions influence arithmetic performance and how such influence changes with age during childhood? To address these issues, I used a within-trial emotion induction procedure while children solve arithmetic problems. More specifically, 8-15 year-old participants (N = 207) solved arithmetic problems (8 + 4 = 13. True? False?) that were displayed superimposed on emotionally negative or neutral pictures. The main results showed (a) poorer performance in emotionally negative conditions in all age groups, (b) larger deleterious effects of negative emotions on harder problems, (c) decreased effects of emotions as children grow older, and (d) sequential carry-over effects of emotions in all age groups such that larger decreased performance under emotion condition relative to neutral condition occurred on current trials immediately preceded by emotional trials. These findings have important implications for furthering our understanding of how emotions influence arithmetic performance in children and how this influence changes during childhood.

Influence of emotional stimuli on metacognition: A study in arithmetic.

We investigate the role of negative emotional stimuli on direct and indirect metacognition, and document age-related differences in this role during adulthood. Participants were presented with negative or neutral pictures while asked to select which of two available strategies was the better strategy to find approximate estimates of two-digit multiplication problems. Following each strategy selection, participants provided either a direct (confidence judgment; Expt. 1) or an indirect (opt-out judgment; Expt. 2) evaluation of their strategy choice. Negative emotional stimuli decreased metacognitive accuracy for arithmetic strategy selection, but only when indirect metacognitive measures were collected. No differences were found when direct metacognitive judgments were requested. The effects of emotional stimuli on indirect metacognition and lack of effects on direct metacognition were found in both young and older adults. These findings have important implications for our understanding of the mechanisms underlying the effects of emotion on metacognition in young and older adults.

Protein kinases and protein phosphatases encoded in the Ciona robusta genome.

Protein kinases (PKs) and protein phosphatases (PPs) regulate the phosphorylation of proteins that are involved in a variety of biological processes. To study such biological processes systematically, it is important to know the whole repertoire of PKs and PPs encoded in a genome. In the present study, we surveyed the genome of an ascidian (Ciona robusta or Ciona intestinalis type A) to comprehensively identify the genes that encoded PKs and PPs. Because ascidians belong to the sister group of vertebrates, a comparison of the whole repertoire of PKs and PPs of ascidians with those of vertebrates may help to delineate the complements of these proteins that were present in the last common ancestor of these two groups of animals. Our results show that the repertory of PPs was much more expanded in vertebrates than the repertory of PKs. We also showed that approximately 75% of PKs and PPs were expressed during development from eggs to larvae. Thus, the present study provides catalogs for PKs and PPs encoded in the ascidian genome. These catalogs will be useful for systematic studies of biological processes that involve phosphorylation and for evolutionary studies of the origin of vertebrates.

Methods for the Study of Apical Constriction During Ascidian Gastrulation.

Gastrulation is the first major morphogenetic event during ascidian embryogenesis. Ascidian gastrulation begins with the invagination of the endodermal progenitors, a two-step process driven by individual cell shape changes of endoderm cells. During the first step, endoderm cells constrict apically, thereby flattening the vegetal side of the embryo. During the second step, endoderm cells shorten along their apicobasal axis and tissue invagination ensues. Individual cell shape changes are mediated by localized actomyosin contractile activity. Here, we describe methods used during ascidian endoderm apical constriction to study myosin activity and cellular morphodynamics with confocal and light sheet microscopy and followed by quantitative image analysis.

Effects of presentation modality and duration on children's strategy use: A study in computational estimation.

Two experiments were run to determine how presentation modality and duration influence children's arithmetic performance and strategy selection. Third and fourth graders were asked to find estimates for two-digit addition problems (e.g., 52 + 39). Children were tested in three conditions: (1) time-unlimited visual, (2) time-limited visual, or (3) time-limited auditory conditions. Moreover, we assessed children's working-memory updating and arithmetic fluency. Children were told which strategy to use on each problem to assess arithmetic performance while executing strategies, in Experiment 1, and were asked to choose the best strategy of three available strategies to assess strategy selection, in Experiment 2. Presentation modality influenced strategy execution (i.e., children were faster and more accurate in problems under visual than auditory conditions) but only in children with low updating abilities. In contrast, presentation modality had no effect on children's strategy selection. Presentation duration had an effect on both strategy execution and strategy selection with time-limited presentation leading to a decline in children's performance. Interestingly, specifically in children with low updating abilities, time-limited presentation led to poorer performance. Hence, efficient updating seemed to compensate for detrimental effects of auditory in comparison to visual and time-limited in comparison to time-unlimited presentation. These findings have important implications for determining conditions under which children execute strategies most efficiently and select the best strategy on each problem most often, as well as for understanding mechanisms underlying strategic behaviour.

Age-related differences in how negative emotions influence arithmetic performance.

In this study, we investigated the role of negative emotions on arithmetic and whether this role changes with aging during adulthood. Young and older adults were asked to verify one-digit addition problems (Experiment 1) and to estimate the results of two-digit multiplication problems (Experiment 2). In both experiments, easier and harder problems were displayed superimposed on emotionally neutral (e.g. mushrooms) or emotionally negative (e.g. a corpse) pictures. In both simple and complex arithmetic, young and older adults obtained poorer arithmetic performance under negative emotion conditions, especially while solving harder problems. Most interesting, deleterious effects of negative emotions on arithmetic performance were larger in young than in older adults. These findings have important implications for further our understanding of the role of negative emotions in the domain of arithmetic and age-related differences in this role.

Mechanical and genetic control of ascidian endoderm invagination during gastrulation.

Gastrulation is a near universal developmental process of animal embryogenesis, during which dramatic morphogenetic events take place: the mesodermal and endodermal tissues are internalized, the ectoderm spreads to cover the embryo surface, and the animal body plan and germ layers are established. Morphogenesis during gastrulation has long been considered the result of spatio-temporally localised forces driven by the transcriptional programme of the embryo. Recent work has shown that tissue rheological properties, which define the mechanical response of tissues to internally-generated or external forces, are also important dynamic regulators of gastrulation. Here, we first introduce how embryonic mechanics can be represented, before outlining current knowledge of the mechanical and genetic control of gastrulation in ascidians, invertebrate marine chordates which develop with invariant cell lineages and a solid-like rheological behaviour until the neurula stages. We discuss the potential of these organisms for the experimental and computational whole-embryo characterisation of the mechanisms shaping gastrulation, and how they may inform the more complex tissue internalization strategies used by other model organisms.

Effects of prior-task failure on arithmetic performance: A study in young and older adults.

Effects of prior-task failure (i.e., decreased performance on a target task following failure on a prior task) were tested in young and older adults. Young and older participants (N=120) accomplished a computational estimation task (i.e., providing the best estimates to arithmetic problems) before and after accomplishing a dot comparison task in a control or in a failure condition. Both groups decreased their performance on the target computational estimation following failure on the prior dot comparison task. Also, prior-task failure led young and older adults to select the better strategy less often and to use the easier strategy more often. Our findings show, for the first time, impaired performance after experiencing failure in both young and older adults. We discuss implications of these findings for further our understanding of effects of task transitions (i.e., prior-task success and failure) on cognitive performance.

Cultural Differences in Susceptibility to Stereotype Threat: France versus India.

OBJECTIVES: Negative aging stereotypes make older adults perform below their true potential in a number of cognitive domains. This phenomenon, known as Age-Based Stereotype Threat, is currently viewed as a powerful factor contributing to an overestimation of cognitive decline in normal aging. However, age-based stereotype threat has been investigated almost exclusively in Western countries. Whether this phenomenon is universal or culture-specific is unknown. METHOD: Here, we first ran a pilot study (N = 106) in which we assessed French and Indian participants' attitudes towards aging. Then, we assessed stereotype threat effects on arithmetic problem-solving performance and strategies in French and Indian older adults (N = 104). RESULTS: We found that French older adults have more negative implicit attitudes towards aging than Indian older adults. We also found that culture modulates age-based stereotype threat effects. Whereas French older adults experienced stereotype threat on both selection and execution of strategies on all arithmetic problems, Indian older adults experienced this threat only in their strategy selection on harder problems. Most interestingly, cultural differences emerged on arithmetic problems under stereotype threat condition, where otherwise no cultural differences were found in the control condition. DISCUSSION: Our findings have important implications for understanding how cultural contexts change aging effects on human cognition and age-related difference in cognitive performance.

Alzheimer's disease disrupts domain-specific and domain-general processes in numerosity estimation.

INTRODUCTION: This study investigated how Alzheimer's Disease (AD) affects numerosity estimation abilities (e.g., finding the approximate number of items in a collection). METHOD: Across two experiments, performance from HOA (i.e., Healthy Older Adults; N = 48) and AD patients (N = 50) was compared on dot comparison tasks. Participants were presented with two dot arrays and had to select the more numerous dot array in comparison tasks. They also took a Simon task and a number-line tasks (i.e., number-line tasks in which they had to indicate the position of a number on a line 0 to 100 or on a line 0 to 1,000 in the number-line task). RESULTS: In Experiment 1, (a) AD patients obtained significantly poorer performance while comparing collections of dots, especially harder (small-ratio) collections, (b) these deficits correlated with poorer performance on the number-line task for larger numerosities (i.e., 0 to 1,000), and (c) AD patients showed poorer performance on incongruent (where numerosity and area occupied by dots mismatched) than on congruent items (where both features matched), while HOA showed no congruency effects. Experiment 2 showed (a) congruency effects in both groups when convex hull was tested as an incongruent feature, and (b) comparable sequential modulations of congruency effects in both groups. CONCLUSIONS: Our findings showed that numerosity abilities decline in AD patients, and that this decline results from impaired domain-specific processes (i.e., numerosity processing) and domain-general processes (i.e., inhibition). These findings have important implications to further our understanding of how specific and general cognitive processes contribute to numerosity estimation/comparison performance, and how such contributions change during Alzheimer's disease.

A Nodal/Eph signalling relay drives the transition from apical constriction to apico-basal shortening in ascidian endoderm invagination.

Gastrulation is the first major morphogenetic event during animal embryogenesis. Ascidian gastrulation starts with the invagination of 10 endodermal precursor cells between the 64- and late 112-cell stages. This process occurs in the absence of endodermal cell division and in two steps, driven by myosin-dependent contractions of the acto-myosin network. First, endoderm precursors constrict their apex. Second, they shorten apico-basally, while retaining small apical surfaces, thereby causing invagination. The mechanisms that prevent endoderm cell division, trigger the transition between step 1 and step 2, and drive apico-basal shortening have remained elusive. Here, we demonstrate a conserved role for Nodal and Eph signalling during invagination in two distantly related ascidian species, Phallusia mammillata and Ciona intestinalis Specifically, we show that the transition to step 2 is triggered by Nodal relayed by Eph signalling. In addition, our results indicate that Eph signalling lengthens the endodermal cell cycle, independently of Nodal. Finally, we find that both Nodal and Eph signals are dispensable for endoderm fate specification. These results illustrate commonalities as well as differences in the action of Nodal during ascidian and vertebrate gastrulation.