Prenatal Diagnosis of Down Syndrome

The chapter’s contribution to the book explores the prenatal modalities to diagnose Down syndrome (DS). The current knowledge in the field of genetic sonographic markers is presented, along the performance of current policies as well as the potential of new emerging genetic techniques. Besides the screening or testing pregnancy algorithms, the chapter describes the power of prenatal diagnostic techniques, namely, the advantages and the complications of the invasive genetic maneuvers. The progress in prenatal diagnosis of Down syndrome is one of the most important in prenatal medicine in the last decades. The methods vary in terms of detection rates, acceptability, costs, and potential complications. Although the early genetic screening was improved, ultrasound evaluation should not be dismissed, as the first-trimester sonography has the potential to diagnose the majority of major fetal abnormalities

Elaboration of a model of Pavlovian learning and performance: HeiDI

The model elaborated here adapts the influential pooled error term, first described by Allan R. Wagner and his colleague Robert A. Rescorla, to govern the formation of reciprocal associations between any pair of stimuli that are presented on a given trial. In the context of Pavlovian conditioning, these stimuli include various conditioned and unconditioned stimuli. This elaboration enables the model to deal with cue competition phenomena, including the relative validity effect, and evidence implicating separate error terms and attentional processes in association formation. The model also includes a performance rule, which provides a natural basis for (individual) variation in the strength and nature of conditioned behaviors that are observed in Pavlovian conditioning procedures. The new model thereby begins to address theoretical and empirical issues that were apparent when the Rescorla-Wagner model was first described, together with research inspired by the model over ensuing 50 years

Individual differences in the nature of conditioned behavior across a conditioned stimulus: adaptation and application of a model

Pavlovian conditioning procedures produce marked individual differences in the form of conditioned behavior. For example, when rats are given conditioning trials in which the temporary insertion of a lever into an operant chamber (the conditioned stimulus, CS) is paired with the delivery of food (the unconditioned stimulus, US), they exhibit knowledge of the leverfood relationship in different ways. For some rats (known as sign-trackers) interactions with the lever dominate, while for others (goal-trackers) approaching the food well dominates. A formal model of Pavlovian conditioning (HeiDI) attributes such individual differences in behavior to variations in the perceived salience of the CS and US. An application of the model in which the perceived salience of the CS declines (i.e., adapts) across its duration, predicts changes in these individual differences within the presentation of the CS: The sign-tracking bias is predicted to decline and goal-tracking bias is predicted to increase across the presentation of a lever. The accuracy of these predictions was confirmed though analysis of archival data from female and male rats

Fetal Central Nervous System Abnormalities

Central nervous system (CNS) is one of the most frequent sites for prenatal diagnosed congenital abnormalities (10 per 1000 live births, much higher than the heart—eight per 1000, kidneys—four per 1000, and other fetal systems). Due to the evolving pattern, ultrasound screening for fetal brain malformations is usually performed at 19–22 weeks’ gestation, but severe congenital anomalies can be diagnosed much earlier. This chapter is a short review, structured in eight subchapters: the first one is dedicated to the normal ultrasound aspect of different CNS segments, and the following ones are to detect pathology in prenatal life. We used many ultrasound images and tried to correlate the prenatal findings with the ones obtained postpartum/postabortum for each case, by means of pathology/imaging techniques

Evolutionary Computation Paradigm to Determine Deep Neural Networks Architectures

Image classification is usually done using deep learning algorithms. Deep learning architectures are set deterministically. The aim of this paper is to propose an evolutionary computation paradigm that optimises a deep learning neural network’s architecture. A set of chromosomes are randomly generated, after which selection, recombination, and mutation are applied. At each generation the fittest chromosomes are kept. The best chromosome from the last generation determines the deep learning architecture. We have tested our method on a second trimester fetal morphology database. The proposed model is statistically compared with DenseNet201 and ResNet50, proving its competitiveness

The nature of phenotypic variation in Pavlovian conditioning

Pavlovian conditioning procedures result in dramatic individual differences in the topography of learnt behaviors in rats: When the temporary insertion of a lever into an operant chamber is paired with food pellets, some rats (known as sign-trackers) predominantly interact with the lever, while others (known as goal-trackers) predominantly approach the food well. Two experiments examined the sensitivity of these two behaviors to changing reinforcement contingencies in groups of males and female rats exhibiting the different phenotypes (i.e., sign-trackers and goal-trackers). In both phenotypes, behavior oriented to the food well was more sensitive to contingency changes (e.g., a reversal in which of two levers was reinforced) than was lever-oriented behavior. That is, the nature of the two behaviors differed independently of the rats in which they were manifest. These results indicate that the behavioral phenotypes reflect the parallel operation of a stimulus-stimulus associative process that gives rise to food-well activity and a stimulus-response process that gives rise to leveroriented activity, rather than the operation of a single process (e.g., stimulus-stimulus) that generates both behaviors

The Antenatal Detection of Fetal Limb Anomalies

The etiology of fetal limb abnormalities is very complex, involving different risk factors: chromosomal abnormalities, gene disorders, intrauterine factors, maternal diseases, or exposure to different risk factors. The prevalence of fetal limb anomalies is reported to be approximately 6 in 10,000 live births, and the impairments of the upper limbs seem to present a higher incidence in comparison to the inferior limbs, more often are affected unilaterally and on the right side in comparison to the left side, some being isolate or may associate other anomalies, as a part of an underlying syndrome. According to the current guidelines, the assessment of the fetal limbs should be performed in the late first and early second trimester. Three-dimensional ultrasound provides a better understanding of the fetal anomaly for the parents and helps a better counseling, and it is used to confirm the anomalies detected by the conventional ultrasound. In cases of treatable anomalies, a multidisciplinary approach involving an obstetrician, geneticist, neonatologist, pediatrician, and pediatric orthopedic surgeon is essential to improve the postnatal outcome. Ultrasound examination and genetic counseling for the parents has an important benefit since some conditions present a genetic inheritance, and the recurrence rate in further pregnancies is very high

HeiDI: A model for Pavlovian learning and performance with reciprocal associations

Associative treatments of how Pavlovian conditioning affects conditioned behavior are rudimentary: A simple ordinal mapping is held to exist between the strength of an association (V) between a conditioned stimulus (CS) and an unconditioned stimulus (US; i.e., VCS-US) and conditioned behavior in a given experimental preparation. The inadequacy of this simplification is highlighted by recent studies that have taken multiple measures of conditioned behavior: Different measures of conditioned behavior provide the basis for drawing opposite conclusions about VCS-US across individual animals. Here, we develop a simple model involving reciprocal associations between the CS and US (VCS-US and VUS-CS) that simulates these qualitative individual differences in conditioned behavior. The new model, HeiDI (How excitation and inhibition Determine Ideo-motion), enables a broad range of phenomena to be accommodated, which are either beyond the scope of extant models or require them to appeal to additional (learning) processes. It also provides an impetus for new lines of inquiry and generates novel predictions

Individual variation in the vigor and form of Pavlovian conditioned responses: analysis of a model system

Pavlovian conditioning results in individual variation in the vigor and form of acquired behaviors. Here, we describe a general-process model of associative learning (HeiDI; How excitation and inhibition determine ideo-motion) that provides an analysis for such variation together with a range of other important group-level phenomena. The model takes as its starting point the idea that pairings of a conditioned stimulus (CS) and an unconditioned stimulus (US) result in the formation of reciprocal associations between their central representations. The asymptotic values of these associations and the rate at which these are reached are held to be influenced by the perceived salience of the CS (αCS) and US (βUS). Importantly, whether this associative knowledge is exhibited in behavior that reflects the properties of the CS (e.g., sign-tracking) or US (e.g., goal-tracking) is also influenced by the relative values of αCS and βUS. In this way, HeiDI provides an analysis for both quantitative and qualitative individual differences generated by Pavlovian conditioning procedures