causal function
Recently Published Documents


TOTAL DOCUMENTS

19
(FIVE YEARS 8)

H-INDEX

5
(FIVE YEARS 0)

2022 ◽  
Author(s):  
Jonathan Sulc ◽  
Jennifer Sjaarda ◽  
Zoltan Kutalik

Abstract Causal inference is a critical step in improving our understanding of biological processes and Mendelian randomisation (MR) has emerged as one of the foremost methods to efficiently interrogate diverse hypotheses using large-scale, observational data from biobanks. Although many extensions have been developed to address the three core assumptions of MR-based causal inference (relevance, exclusion restriction, and exchangeability), most approaches implicitly assume that any putative causal effect is linear. Here we propose PolyMR, an MR-based method which provides a polynomial approximation of an (arbitrary) causal function between an exposure and an outcome. We show that this method provides accurate inference of the shape and magnitude of causal functions with greater accuracy than existing methods. We applied this method to data from the UK Biobank, testing for effects between anthropometric traits and continuous health-related phenotypes and found most of these (84%) to have causal effects which deviate significantly from linear. These deviations ranged from slight attenuation at the extremes of the exposure distribution, to large changes in the magnitude of the effect across the range of the exposure (e.g. a 1 kg/m2 change in BMI having stronger effects on glucose levels if the initial BMI was higher), to non-monotonic causal relationships (e.g. the effects of BMI on cholesterol forming an inverted U shape). Finally, we show that the linearity assumption of the causal effect may lead to the misinterpretation of health risks at the individual level or heterogeneous effect estimates when using cohorts with differing average exposure levels.


2021 ◽  
Author(s):  
Jonathan Sulc ◽  
Jenny Sjaarda ◽  
Zoltan Kutalik

Causal inference is a critical step in improving our understanding of biological processes and Mendelian randomisation (MR) has emerged as one of the foremost methods to efficiently interrogate diverse hypotheses using large-scale, observational data from biobanks. Although many extensions have been developed to address the three core assumptions of MR-based causal inference (relevance, exclusion restriction, and exchangeability), most approaches implicitly assume that any putative causal effect is linear. Here we propose PolyMR, an MR-based method which provides a polynomial approximation of an (arbitrary) causal function between an exposure and an outcome. We show that this method provides accurate inference of the shape and magnitude of causal functions with greater accuracy than existing methods. We applied this method to data from the UK Biobank, testing for effects between anthropometric traits and continuous health-related phenotypes and found most of these (84%) to have causal effects which deviate significantly from linear. These deviations ranged from slight attenuation at the extremes of the exposure distribution, to large changes in the magnitude of the effect across the range of the exposure (e.g. a 1 kg/m2 change in BMI having stronger effects on glucose levels if the initial BMI was higher), to non-monotonic causal relationships (e.g. the effects of BMI on cholesterol forming an inverted U shape). Finally, we show that the linearity assumption of the causal effect may lead to the misinterpretation of health risks at the individual level or heterogeneous effect estimates when using cohorts with differing average exposure levels.


Author(s):  
Aliki Papa ◽  
Mioara Cristea ◽  
Nicola McGuigan ◽  
Monica Tamariz

AbstractHuman culture is the result of a unique cumulative evolutionary process. Despite the importance of culture for our species the social transmission mechanisms underlying this process are still not fully understood. In particular, the role of language—another unique human behaviour—in social transmission is under-explored. In this first direct, systematic comparison of demonstration vs. language-based social learning, we ran transmission chains of participants (6- to 8-year-old children and adults from Cyprus) who attempted to extract a reward from a puzzle box after either watching a model demonstrate an action sequence or after listening to verbal instructions describing the action sequence. The initial seeded sequences included causally relevant and irrelevant actions allowing us to measure transmission fidelity and the accumulation of beneficial modifications through the lens of a subtractive ratchet effect. Overall, we found that, compared to demonstration, verbal instruction specifically enhanced the faithful transmission of causally irrelevant actions (overimitation) in children, but not in adults. Cumulative cultural evolution requires the faithful transmission of sophisticated, complex behaviour whose function may not be obvious. This indicates that, by supporting the retention of actions that appear to lack a causal function specifically by children, language may play a supportive role in cumulative cultural evolution.


2021 ◽  
Author(s):  
Sebastian Reinartz ◽  
Arash Fassihi ◽  
Luciano Paz ◽  
Francesca Pulecchi ◽  
Marco Gigante ◽  
...  

Sensory experiences are accompanied by the perception of the passage of time; a cell phone vibration, for instance, is sensed as brief or long. The neuronal mechanisms underlying the perception of elapsed time remain unknown1. Recent work agrees on a role for cortical processing networks2,3, however the causal function of sensory cortex in time perception has not yet been specified. We hypothesize that the mechanisms for time perception are embedded within primary sensory cortex and are thus governed by the basic rules of sensory coding. By recording and optogenetically modulating neuronal activity in rat vibrissal somatosensory cortex, we find that the percept of stimulus duration is dilated and compressed by optogenetic excitation and inhibition, respectively, during stimulus delivery. A second set of rats judged the intensity of tactile stimuli; here, optogenetic excitation amplified the intensity percept, demonstrating sensory cortex to be the common gateway to both time and stimulus feature processing. The coding algorithms for sensory features are well established4–10. Guided by these algorithms, we formulated a 3–stage model beginning with the membrane currents evoked by vibrissal and optogenetic drive and culminating in the representation of perceived time; this model successfully replicated rats′ choices. Our finding that stimulus coding is intrinsic to sense of time disagrees with dedicated pacemaker-accumulator operation models11–13, where sensory input acts only to trigger the onset and offset of the timekeeping process. Time perception is thus as deeply intermeshed within the sensory processing pathway as is the sense of touch itself14,15 and can now be treated through the computational language of sensory coding. The model presented here readily generalizes to humans14,16 and opens up new approaches to understanding the time misperception at the core of numerous neurological conditions17,18.


2021 ◽  
pp. medhum-2020-012022
Author(s):  
Natalie Riley

This article examines the representation of human genomics in the British historical novel of the 1990s. A form which meditates on the past and its relationship to the present, the historical novel readily lends itself to the exploration of genealogy, heredity and inheritance. Forwarding an understanding of human history, and particularly of family history, as a direct and causal function of the genes, the neo-Darwinian explanation of the genome popular in the 1990s similarly advanced its own teleological relationship between past and present. Reading Jenny Diski’s Monkey’s Uncle (1994), A S Byatt’s Babel Tower (1996) and Zadie Smith’s White Teeth (2000), this essay argues that the historical novel provides a unique form with which to critique the deterministic view of heredity promoted by neo-Darwinism. Focusing on moments of textual anachronism, asynchronicity and repetition in these family sagas, it shows how—at its most transgressive—the historical novel imagines temporal disruptions that bring the present into contact with the past in ways that defamiliarise conventions of linearity, order and progress. Refusing the idea of human history as a single, legible line that underpins neo-Darwinian ideas of genetic inheritance, Diski, Byatt and Smith’s novels are able to interrogate both the temporal logics and cultural capital of 1990s genetic science. While the decade was shaped and defined by popular science speculation and large-scale genetic research projects, such as the Human Genome Project (1990–2003), the novels addressed in this essay ultimately suggest the lively and seductive genocentrism of the 1990s to be inadequate to the task of explaining the complexity and meaning of the lived genome. As Diski, Byatt and Smith’s novels anticipate, the question of the uses, meanings and value of the human genome sequence continue to be of relevance within our current, postgenomic era.


2021 ◽  
Author(s):  
Gustavo Deco ◽  
Yonathan Sanz Perl ◽  
Peter Vuust ◽  
Enzo Tagliazucchi ◽  
Henry Kennedy ◽  
...  

SummaryA fundamental and unanswered question concerns the key topological features of connectivity that are critically relevant for generating the dynamics underlying efficient cortical function. A candidate feature that has recently emerged is that the connectivity of the mammalian cortex follows an exponential distance rule, which uniquely includes a small proportion of long-range high-weight anatomical connections. We investigate how these long-range connections influence whole-brain dynamics with coupled oscillators. To understand the causal function of long-range connections, we first studied these connections in simple ring structures and then in complex empirical brain architectures. A small proportion of long-range connections are sufficient for significantly improving information transmission, i.e. information cascade. Large-scale empirical neuroimaging modelling point to the immense functional benefits for information processing of a brain architecture with long-range coupling that improves the information cascade thanks to the underlying turbulent regime of brain dynamics.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Flora Li ◽  
Sheryl Ball ◽  
Xiaomeng Zhang ◽  
Alec Smith

AbstractWe tested the hypothesis that modulation of neurocomputational inputs to value-based decision-making affects the rationality of economic choices. The brain’s right temporoparietal junction (rTPJ) has been functionally associated with both social behavior and with domain-general information processing and attention. To identify the causal function of rTPJ in prosocial decisions, we administered focal high definition transcranial direct current stimulation (HD-tDCS) while participants allocated money between themselves and a charity in a modified dictator game. Anodal stimulation led to improved rationality as well as increased charitable giving and egalitarianism, resulting in more consistent and efficient choices and increased sensitivity to the price of giving. These results are consistent with the theory that anodal stimulation of the rTPJ increases the precision of value computations in social decision-making. Our results demonstrate that theories of rTPJ function should account for the multifaceted role of the rTPJ in the representation of social inputs into value-based decisions.


2019 ◽  
Author(s):  
Yang Wu ◽  
Hyowon Gweon

Emotional expressions are abundant in children’s lives. What role do these expressions play in children’s learning? Here we ask whether preschool-aged children use others’ emotional expressions to infer the presence of unknown causal functions and guide their exploration accordingly. Children (3.0-4.9 years; N=112) learned about one salient causal function of a novel toy, and then saw an adult play with the toy. Children explored the toy more when the adult expressed surprise than when she expressed happiness (Experiment 1), but only when the adult already knew about the toy's salient function (Experiment 2). These results suggest that children selectively interpret others’ surprise as “vicarious prediction error” based on others’ knowledge, and use it to guide their own exploration and discovery.


2018 ◽  
Vol 39 (12) ◽  
pp. 4724-4732 ◽  
Author(s):  
Eran Dayan ◽  
Jasmine Herszage ◽  
Rony Laor‐Maayany ◽  
Haggai Sharon ◽  
Nitzan Censor

2018 ◽  
pp. 105-133
Author(s):  
Yemima Ben-Menahem

This chapter examines how symmetry principles—despite their a priori appearance—function as causal constraints through their conceptual relation with conservation laws. It first provides an overview of how symmetries are linked to causation by focusing on some of their interconnections with other members of the causal family. It then considers an excellent illustration of the causal function of symmetries in physics, Pauli's exclusion principle, before discussing conservation laws in relation to symmetries. The chapter then explains the distinction between active and passive symmetries, and between global and local symmetries (or geometric versus dynamic symmetries, respectively), as well as gauge theories and the notion of gauge freedom. The chapter concludes with an analysis of Curie's principle and how it is intertwined with symmetries.


Sign in / Sign up

Export Citation Format

Share Document