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Reward processing has been proposed to underpin the atypical social feature of autism spectrum disorder (ASD). However, previous neuroimaging studies have yielded inconsistent results regarding the specificity of atypicalities for social reward processing in ASD.
Aims
Utilising a large sample, we aimed to assess reward processing in response to reward type (social, monetary) and reward phase (anticipation, delivery) in ASD.
Method
Functional magnetic resonance imaging during social and monetary reward anticipation and delivery was performed in 212 individuals with ASD (7.6–30.6 years of age) and 181 typically developing participants (7.6–30.8 years of age).
Results
Across social and monetary reward anticipation, whole-brain analyses showed hypoactivation of the right ventral striatum in participants with ASD compared with typically developing participants. Further, region of interest analysis across both reward types yielded ASD-related hypoactivation in both the left and right ventral striatum. Across delivery of social and monetary reward, hyperactivation of the ventral striatum in individuals with ASD did not survive correction for multiple comparisons. Dimensional analyses of autism and attention-deficit hyperactivity disorder (ADHD) scores were not significant. In categorical analyses, post hoc comparisons showed that ASD effects were most pronounced in participants with ASD without co-occurring ADHD.
Conclusions
Our results do not support current theories linking atypical social interaction in ASD to specific alterations in social reward processing. Instead, they point towards a generalised hypoactivity of ventral striatum in ASD during anticipation of both social and monetary rewards. We suggest this indicates attenuated reward seeking in ASD independent of social content and that elevated ADHD symptoms may attenuate altered reward seeking in ASD.
How do people make decisions between an immediate but small reward and a delayed but large one? The outcome of such decisions indicates that people discount rewards by their delay and hence these outcomes are well described by discounting functions. However, to understand irregular decisions and dysfunctional behavior one needs models which describe how the process of making the decision unfolds dynamically over time: how do we reach a decision and how do sequential decisions influence one another? Here, we present an attractor model that integrates into and extends discounting functions through a description of the dynamics leading to a final choice outcome within a trial and across trials. To validate this model, we derive qualitative predictions for the intra-trial dynamics of single decisions and for the inter-trial dynamics of sequences of decisions that are unique to this type of model. We test these predictions in four experiments based on a dynamic delay discounting computer game where we study the intra-trial dynamics of single decisions via mouse tracking and the inter-trial dynamics of sequences of decisions via sequentially manipulated options. We discuss how integrating decision process dynamics within and across trials can increase our understanding of the processes underlying delay discounting decisions and, hence, complement our knowledge about decision outcomes.
Infection by parasites or pathogens can have marked physiological impacts on individuals. In birds, infection may affect moult and feather growth, which is an energetically demanding time in the annual cycle. Previous work has suggested a potential link between clinically visible Trichomonas gallinae infection and wing length in turtle doves Streptopelia turtur arriving on breeding grounds. First, T. gallinae infection was characterized in 149 columbids from 5 species, sampled on turtle dove wintering grounds in Senegal during the moulting period, testing whether infection by T. gallinae is linked to moult. Trichomonas gallinae prevalence was 100%, so rather than testing for differences between infected and uninfected birds, we tested for differences in moult progression between birds infected by different T. gallinae strains. Twelve strains of T. gallinae were characterized at the internal transcribed spacer 1 (ITS1)/5.8S/ITS2 region, of which 6 were newly identified within this study. In turtle doves only, evidence for differences in wing length by strain was found, with birds infected by strain Tcl-1 having wings nearly 6 mm longer than those infected with strain GEO. No evidence was found for an effect of strain identity within species on moult progression, but comparisons between infected and uninfected birds should be further investigated in species where prevalence is lower.
Reaction time variability (RTV) has been estimated using Gaussian, ex-Gaussian, and diffusion model (DM) indices. Rarely have studies examined interrelationships among these performance indices in childhood, and the use of reaction time (RT) computational models has been slow to take hold in the developmental psychopathology literature. Here, we extend prior work in adults by examining the interrelationships among different model parameters in the ABCD sample and demonstrate how computational models of RT can clarify mechanisms of time-on-task effects and sex differences in RTs.
Method:
This study utilized trial-level data from the stop signal task from 8916 children (9–10 years old) to examine Gaussian, ex-Gaussian, and DM indicators of RTV. In addition to describing RTV patterns, we examined interrelations among these indicators, temporal patterns, and sex differences.
Results:
There was no one-to-one correspondence between DM and ex-Gaussian parameters. Nonetheless, drift rate was most strongly associated with standard deviation of RT and tau, while nondecisional processes were most strongly associated with RT, mu, and sigma. Performance worsened across time with changes driven primarily by decreasing drift rate. Boys were faster and less variable than girls, likely attributable to girls’ wide boundary separation.
Conclusions:
Intercorrelations among model parameters are similar in children as has been observed in adults. Computational approaches play a crucial role in understanding performance changes over time and can also clarify mechanisms of group differences. For example, standard RT models may incorrectly suggest slowed processing speed in girls that is actually attributable to other factors.
Risk and risk management are essential elements of farming. We show that strategies to cope with risk often go beyond the level of the individual farm. Cooperation, learning and sharing of risks play a vital role in European agriculture. An enabling environment should support cooperative approaches, enable a diversity of risk management solutions and harness novel technological opportunities.
Carbon, central to astrobiology, shaped the development of the dwarf planet Ceres, a water-rich protoplanet explored by NASA’s Dawn mission. As a candidate ocean world, Ceres has the potential to provide new insights into prebiotic chemistry and habitability. This chapter reviews observations of carbon and organic matter on Ceres by Dawn and Earth-based telescopes. The observations are placed in context with astrophysical processes that produced organic matter in nebular materials from which Ceres grew. We consider mechanisms for destruction and synthesis of organic matter with changing hydrothermal conditions within Ceres’ interior. This is supported by studies of Ceres’ closest meteorite analogs, the aqueously altered carbonaceous chondrites, and halite crystals containing organic matter that may have formed within Ceres. Ultraviolet-, infrared-, and nuclear-spectroscopy show that Ceres’ surface contains a mixture of carbonates and organic matter in concentrations higher than the meteorite analogs. Ceres carbon-rich surface results from a combination of impacts and complex processes that occurred within Ceres’ interior, including low-temperature aqueous alteration, ice-rock fractionation, and modification of the accreted carbon species during serpentinization. This chapter reviews the current state of knowledge about carbon on Ceres, including sources of carbon and organics, parent body processes, remote sensing observations, and their interpretation.
Using our strict definition of Atomic Scale Analytical Tomography (ASAT), we explore the current landscape of materials characterization tools and discuss how electron microscopy, field ion microscopy, and atom probe tomography are each approaching ASAT. State-of-the-art electron microscopy can achieve sub-angstrom spatial resolution imaging in 2-D and small volumes in 3-D but lacks single-atom chemical sensitivity, especially in 3-D. Field Ion Microscopy can achieve 3-D imaging on small volumes but not for all materials. Atom probe tomography can achieve single-atom elemental quantification in 3-D but lacks the spatial resolution necessary for ASAT. The chapter concludes with a comparison of the different techniques and discusses how different techniques may be complementary.
The historical backdrop for the role of microscopy in the development of human knowledge is reviewed. Atomic-scale investigations are a logical step in a natural progression of increasingly more powerful microscopies. A brief outline of the concept of atomic-scale analytical tomography (ASAT) is given, and its implications for science and technology are anticipated. The intersection of ASAT with advanced computational materials engineering is explored. The chapter concludes with a look toward a future where ASAT will become common.
We discuss how ASAT has the potential to make important advances on critical frontiers in crystallography. These key frontiers include unequivocal quantification of the nearest-neighbour relationships in materials, compositional information, and details of the degree of both short-range order and long-range order. Interfaces represent a particular opportunity. We discuss the present challenges in experimental microscopy-based methods to incorporate both the structural crystallographic information at crystal interfaces with the local chemical compositional information. We anticipate that ASAT will drive forward the field of interface science and interface engineering.
We conclude our contribution with a prospective and optimistic look to the art of what might be possible with the advent of ASAT. We see a convergence between the digital or computational world and the experimental, and envisage ASAT as an enabler for the design and development of new materials. This potential arises because real-world 3D atomic-scale information will bring direct insights into thermodynamic, kinetic, and engineering properties. Moreover, when coupled with machine learning and other computational techniques, it may be envisaged that discovery-based procedures could follow that adjust the observed real-world atomistic configurations toward configurations that exhibit the desired engineering properties. This will fundamentally change the role of microscopy from a tool that provides inference to a materials behaviour to one that provides a quantitative assessment. This opens the pathway to atomic-scale materials informatics.
A complete, albeit brief review of the history of atoms and atomic-scale microscopy is offered. From the concept of the atom developed by Greek philosophers to the ultimate microscopy, the path of development is examined. Atomic-Scale Analytical Tomography (ASAT) is cited as the ultimate microscopy in the sense that the objects, atoms, are the smallest building blocks of nature. The concept of atoms developed as the scientific method grew in application and sophistication beginning in the Middle Ages. The first images of atoms were finally obtained in the mid-twentieth century. Early field ion microscopy evolved eventually into three-dimensional atom probe tomography. The crucial role of the electron microscope in atomic-scale microscopy is examined. Recently, combining atom probe tomography and electron microscopy has emerged as a path toward ASAT. The chapter concludes with the point that ASAT can be expected in the next decade.
Based on the discussion in Chapters 4 and 5, combining information from both electron microscopy, presumably (Scanning) Transmission Electron Microscopy ((S)TEM), and Atom Probe Tomography (APT) is a likely path toward ASAT. Experimentally, concurrent (S)TEM and APT may appear to be a straightforward experiment, but the instrumentation required can be complex and require significant capital investment. In this chapter, we consider what instrumentation is necessary for each technique and what could be done to both simplify and improve the ASAT technique in a combined instrument that solves many of the complexities in experimentation. Experimental conditions such as vacuum pressure, cryogenic temperatures, electron imaging and diffraction, laser wavelength and positioning, and specimen holder designs must all be taken into account.