A parametric approach for smaller and better encodings of cardinality constraints

Adequate encodings for high-level constraints are a key ingredient for the application of SAT technology. In particular, cardinality constraints state that at most (at least, or exactly) k out of n propositional variables can be true. They are crucial in many applications. Although sophisticated encodings for cardinality constraints exist, it is well known that for small n and k straightforward encodings without auxiliary variables sometimes behave better, and that the choice of the right trade-off between minimizing either the number of variables or the number of clauses is highly application-dependent. Here we build upon previous work on Cardinality Networks to get the best of several worlds: we develop an arc-consistent encoding that, by recursively decomposing the constraint into smaller ones, allows one to decide which encoding to apply to each sub-constraint. This process minimizes a function λ·num- vars + num-clauses, where λ is a parameter that can be tuned by the user. Our careful experimental evaluation shows that (e.g., for λ = 5) this new technique produces much smaller encodings in variables and clauses, and indeed strongly improves SAT solvers' performance.Postprint (author’s final draft

Neonatal handling decreases unconditioned anxiety, conditioned fear, and improves two-way avoidance acquisition: a study with the inbred Roman high (RHA-I)- and low-avoidance (RLA-I) rats of both sexes

The present study evaluated the long-lasting effects of neonatal handling (H; administered during the first 21 days of life) on unlearned and learned anxiety-related responses in inbred Roman High- (RHA-I) and Low-avoidance (RLA-I) rats. To this aim, untreated and neonatally-handled RHA-I and RLA-I rats of both sexes were tested in the following tests/tasks in baseline acoustic startle (BAS) test, a context-conditioned fear (CCF) test and the acquisition of two-way active –shuttle box- avoidance (SHAV). RLA-I rats showed higher unconditioned (NOE, ZM, BAS) and conditioned (CCF, SHAV) anxiety. H treatment increased exploration of the novel object in the NOE test as well as exploration of the open sections of the ZM test in both rat strains and sexes, although the effects were relatively more marked in the (high anxious) RLA-I strain and in females. Neonatal handling did not affect BAS, but reduced context-conditioned fear in both strains and sexes, and improved shuttle box avoidance acquisition especially in RLA-I (and particularly in females) and in female RHA-I rats. These are completely novel findings, and may suggest that H-induced changes in hippocampal function, which is enhanced in RLA-Is vs RHA-I rats, could be a candidate mechanism underlying the observed long-lasting benefits of neonatal handling on known hippocampal-dependent responses/tasks

Internet Gaming Disorder Clustering Based on Personality Traits in Adolescents, and Its Relation With Comorbid Psychological Symptoms

In recent years, the evidence regarding Internet Gaming Disorder (IGD) suggests that some personality traits are important risk factors for developing this problem. The heterogeneity involved in problematic online gaming and differences found in the literature regarding the comorbid psychopathology associated with the problem could be explained through different types of gamers. Clustering analysis can allow organization of a collection of personality traits into clusters based on similarity. The objectives of this study were: (1) to obtain an empirical classification of IGD patients according to personality variables and (2) to describe the resultant groups in terms of clinical and sociodemographic variables. The sample included 66 IGD adolescent patients who were consecutive referrals at a mental health center in Barcelona, Spain. A Gaussian mixture model cluster analysis was used in order to classify the subjects based on their personality. Two clusters based on personality traits were detected: type I "higher comorbid symptoms" (n = 24), and type II "lower comorbid symptoms" (n = 42). The type I included higher scores in introversive, inhibited, doleful, unruly, forceful, oppositional, self-demeaning and borderline tendency traits, and lower scores in histrionic, egotistic and conforming traits. The type I obtained higher scores on all the Symptom Check List-90 items-Revised, all the State-Trait Anxiety Index scales, and on the DSM-5 IGD criteria. Differences in personality can be useful in determining clusters with different types of dysfunctionality

Contribution of the Roman rat lines/strains to personality neuroscience: neurobehavioral modeling of internalizing/externalizing psychopathologies

The Roman high-avoidance (RHA) and low-avoidance (RLA) rat lines/strains were established in Rome through bidirectional selection of Wistar rats for rapid (RHA) or extremely poor (RLA) acquisition of a two-way active avoidance task. Relative to RHAs, RLA rats exhibit enhanced threat sensitivity, anxiety, fear and vulnerability to stress, a passive coping style and increased sensitivity to frustration. Thus, RLA rats’ phenotypic profile falls well within the “internalizing” behavior spectrum. Compared with RLAs and other rat strains/stocks, RHAs present increased impulsivity and reward sensitivity, deficits in social behavior and attentional/cognitive processes, novelty-induced hyper-locomotion and vulnerability to psychostimulant sensitization and drug addiction. Thus, RHA rats’ phenotypes are consistent with a “disinhibiting externalizing” profile. Many neurobiological/molecular traits differentiate both rat lines/strains. For example, relative to RLA rats, RHAs exhibit decreased function of the prefrontal cortex (PFC), hippocampus and amygdala, increased functional tone of the mesolimbic dopamine system, a deficit of central metabotropic glutamate-2 (mGlu2) receptors, increased density of serotonin 5-HT2A receptors in the PFC, impairment of GABAergic transmission in the PFC, alterations of several synaptic markers and increased density of pyramidal immature dendrític spines in the PFC. These characteristics suggest an immature brain of RHA rats and are reminiscent of schizophrenia features like hypofrontality and disruption of the excitation/inhibition cortical balance. We review evidence supporting RLA rats as a valid model of anxiety/fear, stress and frustration vulnerability, whereas RHA rats represent a promising translational model of neurodevelopmental alterations related to impulsivity, schizophrenia-relevant features and comorbidity with drug addiction vulnerability

Modelant la simptomatologia de l’esquizofrènia en les soques de rates romanes i en les genèticament heterogènies NIH-HS

En aquesta Tesi es presenten quatre estudis que tenien l’objectiu de validar les rates romanes (RHA-I i RLA-I) com a model animal d’alguns símptomes rellevants per a l’esquizofrènia. L’Estudi 1 tenia com a objectiu principal fer la caracterització conductual de les rates romanes d’alta i baixa evitació (RHA-I i RLA-I, respectivament) i de les rates genèticament heterogènies NIH-HS en dues tasques relacionades amb els símptomes de l’esquizofrènia, com són els dèficits de filtratge atencional, mesurats amb la inhibició de la resposta de sobresalt per un prepols (PPI), i els dèficits de memòria de treball. A l’Estudi 2 es van investigar els efectes de l’aïllament social, sobre diverses conductes/fenotips: el filtratge atencional (PPI), l’ansietat, la hiperactivitat motora i la memòria. A l’Estudi 3 es van avaluar els efectes de substàncies antipsicòtiques (haloperidol i clozapina) i propsicòtiques (apomorfina, MK-801, DOI) sobre la PPI i l’activitat motora. Finalment, el quart estudi tenia l’objectiu d’estudiar les diferències d’expressió gènica de HTR1A i HTR2A entre les soques romanes, i entre rates NIH-HS seleccionades pel seus nivells extrems de PPI. Els resultats de l’Estudi 1 mostren que les rates RHA-I, comparades amb les RLA-I i les NIH-HS, tenen dèficits de PPI i de memòria de treball, i que les rates NIH-HS presenten valors alts (semblants als de les rates RLA-I) tant de PPI com de memòria de treball. A més a més, els resultats mostren correlacions positives entre la PPI i la memòria de treball. A l’Estudi 2, les rates RHA-I aïllades socialment manifesten dèficits de PPI, augment de l’ansietat, hiperactivitat i dèficits d’aprenentatge. A l’Estudi 3 vam observar que les rates RHA-I són més sensibles als efectes dels agonistes/antagonistes dopaminèrgics (apomorfina/haloperidol) sobre la PPI. Per altra banda, les rates RLA-I són més sensibles als efectes dels fàrmacs agonistes/antagonistes serotoninèrgics (DOI/clozapina) i a l’ antagonista NMDA (MK-801) sobre la PPI. Els resultats de l’Estudi 4 mostren diferències entre soques en l’expressió gènica al còrtex prefrontal (dels gens HTR1A i HTR2A) i a l’estriat (del gen HTR2A), on les rates RHA-I mostren un increment de l’expressió en ambdós casos. Les rates NIH-HS seleccionades pels seus nivells de PPI també mostren diferències d’expressió del gen HTR1A al còrtex prefrontal. Globalment, els estudis augmenten la validesa aparent (Estudi 1 i 2), la validesa predictiva (Estudi 3) i la validesa de constructe (Estudi 4 i el 2 en menor mesura) de les rates RHA-I com a model animal d’alguns dels símptomes relacionats amb l’esquizofrènia.In this Thesis we present four studies that were aimed at validating the Roman rat strains (RHA-I and RLA-I) as an animal model of some schizophrenia-relevant symptoms. Study 1 was devoted to behaviorally characterize the Roman high- (RHA-I) and low-avoidance (RLA-I) rats, and the genetically heterogeneous rats (NIH-HS), in two tasks related to some schizophrenia-relevant symptoms, i.e. prepulse inhibition of the startle response (PPI, a measure of sensorimotor gating) and spatial working memory measured in the Morris water maze. In Study 2, we investigated the effects of chronic social isolation on several behaviours/phenotypes in the Roman rats: sensorimotor gating (PPI), anxiety, locomotor hyperactivity and spatial memory. In Study 3 we evaluated the effects of several antipsychotics (haloperidol and clozapine) and propsychotics (apomorphine, DOI and MK-801) on PPI and locomotor activity. Finally, Study 4 was aimed to evaluate whether there are differences in gene expression (of the HTR1A and HTR2A genes) between the Roman rat strains, and to see if these differences also appear between NIH-HS rats selected for their extremely high or low levels of PPI. The results of Study 1 show that RHA-I rats have PPI and working memory deficits and that NIH-HS rats present high levels of PPI and working memory. There are positive associations between PPI and working memory, since rats with high PPI (RLA-I and NIH-HS) also have a better performance in the working memory task. In Study 2, the socially-isolated RHA-I rats exhibit PPI deficits, increased anxiety, locomotor hyperactivity and spatial learning deficits. Study 3 shows that RHA-I rats are more sensitive to the effects of dopamine agonists/antagonists (apomorphine/haloperidol) on PPI, whereas RLA-I rats are more sensitive to the effects of serotonin agonists/antagonists (DOI/clozapine) and to the NMDA antagonist (MK-801) in the PPI test. The results of Study 4 show differences in gene expression between the Roman rats in the prefrontal cortex (HTR1A and HTR2A genes) and in the striatum (HTR2A gene), with RHA-I rats having enhanced expression of these genes. The NIH-HS rats selected for their extreme PPI levels also show differences of expression of the HTR1A gene in the prefrontal cortex. As a whole, the studies of the present Thesis increase the apparent validity (Study 1 and 2), the predictive validity (Study 3) and construct validity (Study 4 and Study 2 to a lesser extent) of the RHA-I rats as an animal model of some of the symptoms related to schizophrenia