Pub Date : 2024-09-18DOI: 10.1093/pnasnexus/pgae402
Fabiola Ramelli, Jan Henneberger, Christopher Fuchs, Anna J Miller, Nadja Omanovic, Robert Spirig, Huiying Zhang, Robert O David, Kevin Ohneiser, Patric Seifert, Ulrike Lohmann
The representation of cloud processes in models is one of the largest sources of uncertainty in weather forecast and climate projections. While laboratory settings offer controlled conditions for studying cloud processes, they cannot reproduce the full range of conditions and interactions present in natural cloud systems. To bridge this gap, here we leverage weather modification, specifically glaciogenic cloud seeding, to investigate ice growth rates within natural clouds. Seeding experiments were conducted in supercooled stratus clouds (at −8 to −5 °C) using an uncrewed aerial vehicle, and the created ice crystals were measured 4-10 min downwind by in situ and ground-based remote sensing instrumentation. We observed substantial variability in ice crystal growth rates within natural clouds, attributed to variations in ice crystal number concentrations and in the supersaturation, which is difficult to reproduce in the laboratory and which implies faster precipitation initiation than previously thought. We found that for the experiments conducted at −5.2 °C, the ice crystal populations grew nearly linearly during the time interval from 6 to 10 minutes. Our results demonstrate that the targeted use of weather modification techniques can be employed for fundamental cloud research (e.g., ice growth processes, aerosol-cloud interactions), helping to advance cloud microphysics parameterizations and to improve weather forecasts and climate projections.
{"title":"Repurposing weather modification for cloud research showcased by ice crystal growth","authors":"Fabiola Ramelli, Jan Henneberger, Christopher Fuchs, Anna J Miller, Nadja Omanovic, Robert Spirig, Huiying Zhang, Robert O David, Kevin Ohneiser, Patric Seifert, Ulrike Lohmann","doi":"10.1093/pnasnexus/pgae402","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae402","url":null,"abstract":"The representation of cloud processes in models is one of the largest sources of uncertainty in weather forecast and climate projections. While laboratory settings offer controlled conditions for studying cloud processes, they cannot reproduce the full range of conditions and interactions present in natural cloud systems. To bridge this gap, here we leverage weather modification, specifically glaciogenic cloud seeding, to investigate ice growth rates within natural clouds. Seeding experiments were conducted in supercooled stratus clouds (at −8 to −5 °C) using an uncrewed aerial vehicle, and the created ice crystals were measured 4-10 min downwind by in situ and ground-based remote sensing instrumentation. We observed substantial variability in ice crystal growth rates within natural clouds, attributed to variations in ice crystal number concentrations and in the supersaturation, which is difficult to reproduce in the laboratory and which implies faster precipitation initiation than previously thought. We found that for the experiments conducted at −5.2 °C, the ice crystal populations grew nearly linearly during the time interval from 6 to 10 minutes. Our results demonstrate that the targeted use of weather modification techniques can be employed for fundamental cloud research (e.g., ice growth processes, aerosol-cloud interactions), helping to advance cloud microphysics parameterizations and to improve weather forecasts and climate projections.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142249723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1093/pnasnexus/pgae388
Chelsea W Neil, Yun Yang, Haylea Nisbet, Uwaila C Iyare, Lawrence O Boampong, Wenfeng Li, Qinjun Kang, Jeffrey D Hyman, Hari S Viswanathan
Controlling atmospheric warming requires immediate reduction of carbon dioxide (CO2) emissions, as well as the active removal and sequestration of CO2 from current point sources. One promising proposed strategy to reduce atmospheric CO2 levels is geologic carbon sequestration (GCS), where CO2 is injected into the subsurface and reacts with the formation to precipitate carbonate minerals. Rapid mineralization has recently been reported for field tests in mafic and ultramafic rocks. However, unlike saline aquifers and depleted oil and gas reservoirs historically considered for GCS, these formations can have extremely low porosities and permeabilities, limiting storage volumes and reactive mineral surfaces to the pre-existing fracture network. As a result, coupling between geochemical interactions and the fracture network evolution is a critical component of long-term, sustainable carbon storage. In this paper, we summarize recent advances in integrating experimental and modeling approaches to determine the first order processes for carbon mineralization in a fractured mafic/ultramafic rock system. We observe the critical role of fracture aperture, flow, and surface characteristics in controlling the quantity, identity, and morphology of secondary precipitates and present where the influence of these factors can be reflected in newly developed thermo-hydro-mechanical-chemical models. Our findings provide a roadmap for future work on carbon mineralization, as we present the most important system components and key challenges that we are overcoming to enable GCS in mafic and ultramafic rocks.
{"title":"An integrated experiment-modeling approach to identify key processes for carbon mineralization in fractured mafic and ultramafic rocks.","authors":"Chelsea W Neil, Yun Yang, Haylea Nisbet, Uwaila C Iyare, Lawrence O Boampong, Wenfeng Li, Qinjun Kang, Jeffrey D Hyman, Hari S Viswanathan","doi":"10.1093/pnasnexus/pgae388","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae388","url":null,"abstract":"Controlling atmospheric warming requires immediate reduction of carbon dioxide (CO2) emissions, as well as the active removal and sequestration of CO2 from current point sources. One promising proposed strategy to reduce atmospheric CO2 levels is geologic carbon sequestration (GCS), where CO2 is injected into the subsurface and reacts with the formation to precipitate carbonate minerals. Rapid mineralization has recently been reported for field tests in mafic and ultramafic rocks. However, unlike saline aquifers and depleted oil and gas reservoirs historically considered for GCS, these formations can have extremely low porosities and permeabilities, limiting storage volumes and reactive mineral surfaces to the pre-existing fracture network. As a result, coupling between geochemical interactions and the fracture network evolution is a critical component of long-term, sustainable carbon storage. In this paper, we summarize recent advances in integrating experimental and modeling approaches to determine the first order processes for carbon mineralization in a fractured mafic/ultramafic rock system. We observe the critical role of fracture aperture, flow, and surface characteristics in controlling the quantity, identity, and morphology of secondary precipitates and present where the influence of these factors can be reflected in newly developed thermo-hydro-mechanical-chemical models. Our findings provide a roadmap for future work on carbon mineralization, as we present the most important system components and key challenges that we are overcoming to enable GCS in mafic and ultramafic rocks.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142249690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1093/pnasnexus/pgae346
Yan Tao, Olga Viberg, Ryan S Baker, René F Kizilcec
Culture fundamentally shapes people’s reasoning, behavior, and communication. As people increasingly use generative artificial intelligence (AI) to expedite and automate personal and professional tasks, cultural values embedded in AI models may bias people’s authentic expression and contribute to the dominance of certain cultures. We conduct a disaggregated evaluation of cultural bias for five widely used large language models (OpenAI’s GPT-4o/4-turbo/4/3.5-turbo/3) by comparing the models’ responses to nationally representative survey data. All models exhibit cultural values resembling English-speaking and Protestant European countries. We test cultural prompting as a control strategy to increase cultural alignment for each country/territory. For later models (GPT-4, 4-turbo, 4o), this improves the cultural alignment of the models’ output for 71–81% of countries and territories. We suggest using cultural prompting and ongoing evaluation to reduce cultural bias in the output of generative AI.
{"title":"Cultural bias and cultural alignment of large language models","authors":"Yan Tao, Olga Viberg, Ryan S Baker, René F Kizilcec","doi":"10.1093/pnasnexus/pgae346","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae346","url":null,"abstract":"Culture fundamentally shapes people’s reasoning, behavior, and communication. As people increasingly use generative artificial intelligence (AI) to expedite and automate personal and professional tasks, cultural values embedded in AI models may bias people’s authentic expression and contribute to the dominance of certain cultures. We conduct a disaggregated evaluation of cultural bias for five widely used large language models (OpenAI’s GPT-4o/4-turbo/4/3.5-turbo/3) by comparing the models’ responses to nationally representative survey data. All models exhibit cultural values resembling English-speaking and Protestant European countries. We test cultural prompting as a control strategy to increase cultural alignment for each country/territory. For later models (GPT-4, 4-turbo, 4o), this improves the cultural alignment of the models’ output for 71–81% of countries and territories. We suggest using cultural prompting and ongoing evaluation to reduce cultural bias in the output of generative AI.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142249691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1093/pnasnexus/pgae345
Danica Dillion, Curtis Puryear, Longjiao Li, Andre Chiquito, Kurt Gray
Politics and the media in the United States are increasingly nationalized, and this changes how we talk about politics. Instead of reading the local news and discussing local events, people are more often consuming national media and discussing national issues. Unlike local politics, which can rely on shared concrete knowledge about the region, national politics must coordinate large groups of people with little in common. To provide this coordination, we find that national-level political discussions rely upon different themes than local-level discussions, using more abstract, moralized, and power-centric language. The higher prevalence of abstract, moralized, and power-centric language in national vs. local politics was found in political speeches, politician Tweets, and Reddit discussions. These national-level linguistic features lead to broader engagement with political messages, but they also foster more anger and negativity. These findings suggest that the nationalization of politics and the media may contribute to rising partisan animosity.
{"title":"National politics ignites more talk of morality and power than local politics","authors":"Danica Dillion, Curtis Puryear, Longjiao Li, Andre Chiquito, Kurt Gray","doi":"10.1093/pnasnexus/pgae345","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae345","url":null,"abstract":"Politics and the media in the United States are increasingly nationalized, and this changes how we talk about politics. Instead of reading the local news and discussing local events, people are more often consuming national media and discussing national issues. Unlike local politics, which can rely on shared concrete knowledge about the region, national politics must coordinate large groups of people with little in common. To provide this coordination, we find that national-level political discussions rely upon different themes than local-level discussions, using more abstract, moralized, and power-centric language. The higher prevalence of abstract, moralized, and power-centric language in national vs. local politics was found in political speeches, politician Tweets, and Reddit discussions. These national-level linguistic features lead to broader engagement with political messages, but they also foster more anger and negativity. These findings suggest that the nationalization of politics and the media may contribute to rising partisan animosity.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142249692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1093/pnasnexus/pgae359
Nicholas P Camp, Rob Voigt, MarYam G Hamedani, Dan Jurafsky, Jennifer L Eberhardt
Can training police officers on how to best interact with the public actually improve their interactions with community members? This has been a challenging question to answer. Interpersonal aspects of policing are consequential but largely invisible in administrative records commonly used for evaluation. In this study, we offer a solution: body-worn camera footage captures police–community interactions and how they might change as a function of training. Using this footage-as-data approach, we consider changes in officers’ communication following procedural justice training in Oakland, CA, USA, one module of which sought to increase officer-communicated respect during traffic stops. We applied natural language processing tools and expert annotations of traffic stop recordings to detect whether officers enacted the five behaviors recommended in this module. Compared with recordings of stops that occurred prior to the training, we find that officers employed more of these techniques in posttraining stops; officers were more likely to express concern for drivers’ safety, offer reassurance, and provide explicit reasons for the stop. These methods demonstrate the promise of a footage-as-data approach to capture and affect change in police–community interactions.
{"title":"Leveraging body-worn camera footage to assess the effects of training on officer communication during traffic stops","authors":"Nicholas P Camp, Rob Voigt, MarYam G Hamedani, Dan Jurafsky, Jennifer L Eberhardt","doi":"10.1093/pnasnexus/pgae359","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae359","url":null,"abstract":"Can training police officers on how to best interact with the public actually improve their interactions with community members? This has been a challenging question to answer. Interpersonal aspects of policing are consequential but largely invisible in administrative records commonly used for evaluation. In this study, we offer a solution: body-worn camera footage captures police–community interactions and how they might change as a function of training. Using this footage-as-data approach, we consider changes in officers’ communication following procedural justice training in Oakland, CA, USA, one module of which sought to increase officer-communicated respect during traffic stops. We applied natural language processing tools and expert annotations of traffic stop recordings to detect whether officers enacted the five behaviors recommended in this module. Compared with recordings of stops that occurred prior to the training, we find that officers employed more of these techniques in posttraining stops; officers were more likely to express concern for drivers’ safety, offer reassurance, and provide explicit reasons for the stop. These methods demonstrate the promise of a footage-as-data approach to capture and affect change in police–community interactions.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142249693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1093/pnasnexus/pgae412
Cleanthis Michael, Aman Taxali, Mike Angstadt, Omid Kardan, Alexander Weigard, M Fiona Molloy, Katherine L McCurry, Luke W Hyde, Mary M Heitzeg, Chandra Sripada
Socioeconomic resources (SER) calibrate the developing brain to the current context, which can confer or attenuate risk for psychopathology across the lifespan. Recent multivariate work indicates that SER levels powerfully relate to intrinsic functional connectivity patterns across the entire brain. Nevertheless, the neuroscientific meaning of these widespread neural differences remains poorly understood, despite its translational promise for early risk identification, targeted intervention, and policy reform. In the present study, we leverage graph theory to precisely characterize multivariate and univariate associations between SER across household and neighborhood contexts and the intrinsic functional architecture of brain regions in 5,821 youth (9-10 years) from the Adolescent Brain Cognitive Development StudySM. First, we establish that decomposing the brain into profiles of integration and segregation captures more than half of the multivariate association between SER and functional connectivity with greater parsimony (100-fold reduction in number of features) and interpretability. Second, we show that the topological effects of SER are not uniform across the brain; rather, higher SER levels are associated with greater integration of somatomotor and subcortical systems, but greater segregation of default mode, orbitofrontal, and cerebellar systems. Finally, we demonstrate that topological associations with SER are spatially patterned along the unimodal-transmodal gradient of brain organization. These findings provide critical interpretive context for the established and widespread associations between SER and brain organization. This study highlights both higher-order and somatomotor networks that are differentially implicated in environmental stress, disadvantage, and opportunity in youth.
社会经济资源（SER）能使发育中的大脑适应当前的环境，从而在整个生命周期中增加或减少精神病理学的风险。最近的多变量研究表明，社会经济资源水平与整个大脑的内在功能连接模式密切相关。然而，人们对这些广泛的神经差异的神经科学意义仍然知之甚少，尽管它有望转化为早期风险识别、针对性干预和政策改革的工具。在本研究中，我们利用图论精确描述了《青少年大脑认知发展研究》（Adolescent Brain Cognitive Development StudySM）中 5821 名青少年（9-10 岁）在家庭和邻里环境中的 SER 与大脑区域内在功能结构之间的多变量和单变量关联。首先，我们发现，将大脑分解为整合和分离特征，可以捕捉到 SER 和功能连接性之间一半以上的多元关联，同时具有更高的解析性（特征数量减少 100 倍）和可解释性。其次，我们证明了 SER 的拓扑效应在整个大脑中并不一致；相反，SER 水平越高，躯体运动系统和皮层下系统的整合程度越高，但默认模式、眶额叶和小脑系统的分离程度越高。最后，我们证明了与 SER 的拓扑关联是沿着大脑组织的单模态-跨模态梯度空间模式化的。这些发现为 SER 与大脑组织之间已建立的广泛联系提供了重要的解释背景。这项研究强调了高阶网络和躯体运动网络与青少年的环境压力、劣势和机遇之间的不同关联。
{"title":"Socioeconomic resources in youth are linked to divergent patterns of network integration/segregation across the brain’s transmodal axis","authors":"Cleanthis Michael, Aman Taxali, Mike Angstadt, Omid Kardan, Alexander Weigard, M Fiona Molloy, Katherine L McCurry, Luke W Hyde, Mary M Heitzeg, Chandra Sripada","doi":"10.1093/pnasnexus/pgae412","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae412","url":null,"abstract":"Socioeconomic resources (SER) calibrate the developing brain to the current context, which can confer or attenuate risk for psychopathology across the lifespan. Recent multivariate work indicates that SER levels powerfully relate to intrinsic functional connectivity patterns across the entire brain. Nevertheless, the neuroscientific meaning of these widespread neural differences remains poorly understood, despite its translational promise for early risk identification, targeted intervention, and policy reform. In the present study, we leverage graph theory to precisely characterize multivariate and univariate associations between SER across household and neighborhood contexts and the intrinsic functional architecture of brain regions in 5,821 youth (9-10 years) from the Adolescent Brain Cognitive Development StudySM. First, we establish that decomposing the brain into profiles of integration and segregation captures more than half of the multivariate association between SER and functional connectivity with greater parsimony (100-fold reduction in number of features) and interpretability. Second, we show that the topological effects of SER are not uniform across the brain; rather, higher SER levels are associated with greater integration of somatomotor and subcortical systems, but greater segregation of default mode, orbitofrontal, and cerebellar systems. Finally, we demonstrate that topological associations with SER are spatially patterned along the unimodal-transmodal gradient of brain organization. These findings provide critical interpretive context for the established and widespread associations between SER and brain organization. This study highlights both higher-order and somatomotor networks that are differentially implicated in environmental stress, disadvantage, and opportunity in youth.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1093/pnasnexus/pgae333
Barnabas Szaszi, Hooman Habibnia, Josephine Tan, Oliver P Hauser, Jon M Jachimowicz
The misperception of income inequality is often touted as a critical barrier to more widespread support of redistributive policies. Here, we examine to what extent and why (mis)perceptions vary systematically across the income distribution. Drawing on data from four studies (N = 2,744)—including a representative sample and preregistered incentive-compatible experiments—we offer converging evidence that people specifically underestimate the amount of income held by the top of the income distribution. While this selective underestimation is likely driven by multiple mechanisms, including systemic factors, we find that cognitive biases contribute to the observed pattern of results. The rise of inequality in many developed countries has been documented before, and the fact that this growing inequality is largely driven by the outsized gains of the richest individuals may pose new challenges previously underappreciated: our theory and findings highlight that cognitive biases pose a key obstacle to people's recognition of the concentration of income among the richest individuals, and may potentially distort their preferences for redistribution. We conclude by discussing future directions for research and the importance of incorporating behavioral and cognitive limitations into the design of redistributive public policy.
{"title":"Selective insensitivity to income held by the richest","authors":"Barnabas Szaszi, Hooman Habibnia, Josephine Tan, Oliver P Hauser, Jon M Jachimowicz","doi":"10.1093/pnasnexus/pgae333","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae333","url":null,"abstract":"The misperception of income inequality is often touted as a critical barrier to more widespread support of redistributive policies. Here, we examine to what extent and why (mis)perceptions vary systematically across the income distribution. Drawing on data from four studies (N = 2,744)—including a representative sample and preregistered incentive-compatible experiments—we offer converging evidence that people specifically underestimate the amount of income held by the top of the income distribution. While this selective underestimation is likely driven by multiple mechanisms, including systemic factors, we find that cognitive biases contribute to the observed pattern of results. The rise of inequality in many developed countries has been documented before, and the fact that this growing inequality is largely driven by the outsized gains of the richest individuals may pose new challenges previously underappreciated: our theory and findings highlight that cognitive biases pose a key obstacle to people's recognition of the concentration of income among the richest individuals, and may potentially distort their preferences for redistribution. We conclude by discussing future directions for research and the importance of incorporating behavioral and cognitive limitations into the design of redistributive public policy.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142249728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-14DOI: 10.1093/pnasnexus/pgae404
Arno Granier, Mihai A Petrovici, Walter Senn, Katharina A Wilmes
Minimization of cortical prediction errors has been considered a key computational goal of the cerebral cortex underlying perception, action and learning. However, it is still unclear how the cortex should form and use information about uncertainty in this process. Here, we formally derive neural dynamics that minimize prediction errors under the assumption that cortical areas must not only predict the activity in other areas and sensory streams but also jointly project their confidence (inverse expected uncertainty) in their predictions. In the resulting neuronal dynamics, the integration of bottom-up and top-down cortical streams is dynamically modulated based on confidence in accordance with the Bayesian principle. Moreover, the theory predicts the existence of cortical second-order errors, comparing confidence and actual performance. These errors are propagated through the cortical hierarchy alongside classical prediction errors and are used to learn the weights of synapses responsible for formulating confidence. We propose a detailed mapping of the theory to cortical circuitry, discuss entailed functional interpretations and provide potential directions for experimental work.
{"title":"Confidence and second-order errors in cortical circuits","authors":"Arno Granier, Mihai A Petrovici, Walter Senn, Katharina A Wilmes","doi":"10.1093/pnasnexus/pgae404","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae404","url":null,"abstract":"Minimization of cortical prediction errors has been considered a key computational goal of the cerebral cortex underlying perception, action and learning. However, it is still unclear how the cortex should form and use information about uncertainty in this process. Here, we formally derive neural dynamics that minimize prediction errors under the assumption that cortical areas must not only predict the activity in other areas and sensory streams but also jointly project their confidence (inverse expected uncertainty) in their predictions. In the resulting neuronal dynamics, the integration of bottom-up and top-down cortical streams is dynamically modulated based on confidence in accordance with the Bayesian principle. Moreover, the theory predicts the existence of cortical second-order errors, comparing confidence and actual performance. These errors are propagated through the cortical hierarchy alongside classical prediction errors and are used to learn the weights of synapses responsible for formulating confidence. We propose a detailed mapping of the theory to cortical circuitry, discuss entailed functional interpretations and provide potential directions for experimental work.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142249726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-14DOI: 10.1093/pnasnexus/pgae408
Birger Wernerfelt
We propose a model in which players take actions that run counter to social norms in part to announce their stand on a social controversy but also, and maybe mostly, to gain image benefits that allow them to join groups that are socially attractive to them. We give several examples, but the “election denial” debate is an important application: Rather than assuming that proponents believe their claims to be true, it suggests that false statements can serve as symbolic actions and help them engage in self-branding for social and psychological gain. Specifically, the willingness to make a controversial statement can be a credible signal because untruth is ill-received by some members of society and therefore entails some costs. It is immaterial whether election deniers believe their claim to be true, but it is important that some members of society believe that it is false and therefore think poorly of those who make it: If there is social consensus about the truth of a statement, it cannot serve a signaling function. The same mechanism explains several other verbal and non-verbal signals associated with different sides of social controversies and analysis of those helps clarify the mechanism.
{"title":"The origin and function of arbitrary signals: Making false statements, having long hair, and smoking Virginia Slims","authors":"Birger Wernerfelt","doi":"10.1093/pnasnexus/pgae408","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgae408","url":null,"abstract":"We propose a model in which players take actions that run counter to social norms in part to announce their stand on a social controversy but also, and maybe mostly, to gain image benefits that allow them to join groups that are socially attractive to them. We give several examples, but the “election denial” debate is an important application: Rather than assuming that proponents believe their claims to be true, it suggests that false statements can serve as symbolic actions and help them engage in self-branding for social and psychological gain. Specifically, the willingness to make a controversial statement can be a credible signal because untruth is ill-received by some members of society and therefore entails some costs. It is immaterial whether election deniers believe their claim to be true, but it is important that some members of society believe that it is false and therefore think poorly of those who make it: If there is social consensus about the truth of a statement, it cannot serve a signaling function. The same mechanism explains several other verbal and non-verbal signals associated with different sides of social controversies and analysis of those helps clarify the mechanism.","PeriodicalId":516525,"journal":{"name":"PNAS Nexus","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142249725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-13DOI: 10.1093/pnasnexus/pgae384
Zhiyuan Li, Laura P Ióca, Ruolin He, Mohamed S Donia
The modular architecture of nonribosomal peptide synthetases (NRPSs) has inspired efforts to study their evolution and engineering. Here, we analyze in detail a unique family of NRPSs from the defensive intracellular bacterial symbiont, Candidatus Endobryopsis kahalalidifaciens. We show that intensive and indiscriminate recombination events erase trivial sequence covariations induced by phylogenetic relatedness, revealing nonmodular functional constraints and clear recombination units. Moreover, we reveal unique substrate specificity determinants for multiple enzymatic domains, allowing us to accurately predict and experimentally discover the products of an orphan NRPS in Ca. E. kahalalidifaciens directly from environmental samples of its algal host. Finally, we expanded our analysis to 1531 diverse NRPS pathways and revealed similar functional constraints to those observed in Ca. E. kahalalidifaciens’ NRPSs. Our findings reveal the sequence bases of genetic exchange, functional constraints, and substrate specificity in Ca. E. kahalalidifaciens’ NRPSs, and highlight them as a uniquely primed system for diversifying evolution.
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