Recovering morphology from local phonotactic constraints

Introduction: Implicit phonotactic knowledge emerges from learners\u2019 exposure to languagespecific distributional information. Gradience in acceptability judgements based on phonotactic knowledge has been extensively reported on for verbal short-term memory, language processing and acquisition [1, 4]. \u2018Wordlikeness\u2019 studies [2] distinguish between two different types of knowledge involved in production/judgement of novel words: (a) phonotactic (string level); (b) lexical (word level). Different statistical models are used to shape the two types of knowledge (bigram/trigram transition probability for (a) and lexical neighborhood for (b) [3]). In this work, we propose that the phonotactic level and the word level should not be conceived of as two independent, blind domains, but rather as interconnected systems interacting in a bottom-up fashion. More specifically, we test the hypothesis that the interplay of phonotactic local constraints and frequency-sensitive word patterns is powerful enough to enable over-ranked morphological patterns to be recovered from rough data. In inflectional languages, such as Italian, function morphemes are predominantly inserted by suffixation and they tend therefore to occupy the right edge of the word. We hypothesize that, in such languages, similarity effects will emerge more salient at the right edge of a word than in other positions, all other things being equal

Towards a systems-level view of cerebellar function::the interplay between cerebellum, basal ganglia and cortex

Contains fulltext : 170319.pdf (Publisher’s version ) (Open Access)Despite increasing evidence suggesting the cerebellum works in concert with the cortex and basal ganglia, the nature of the reciprocal interactions between these three brain regions remains unclear. This consensus paper gathers diverse recent views on a variety of important roles played by the cerebellum within the cerebello-basal ganglia-thalamo-cortical system across a range of motor and cognitive functions. The paper includes theoretical and empirical contributions, which cover the following topics: recent evidence supporting the dynamical interplay between cerebellum, basal ganglia, and cortical areas in humans and other animals; theoretical neuroscience perspectives and empirical evidence on the reciprocal influences between cerebellum, basal ganglia, and cortex in learning and control processes; and data suggesting possible roles of the cerebellum in basal ganglia movement disorders. Although starting from different backgrounds and dealing with different topics, all the contributors agree that viewing the cerebellum, basal ganglia, and cortex as an integrated system enables us to understand the function of these areas in radically different ways. In addition, there is unanimous consensus between the authors that future experimental and computational work is needed to understand the function of cerebellar-basal ganglia circuitry in both motor and non-motor functions. The paper reports the most advanced perspectives on the role of the cerebellum within the cerebello-basal ganglia-thalamo-cortical system and illustrates other elements of consensus as well as disagreements and open questions in the field

Safety of intravenous ferric carboxymaltose versus oral iron in patients with nondialysis-dependent CKD: an analysis of the 1-year FIND-CKD trial.

Background: The evidence base regarding the safety of intravenous (IV) iron therapy in patients with chronic kidney disease (CKD) is incomplete and largely based on small studies of relatively short duration. Methods: FIND-CKD (ClinicalTrials.gov number NCT00994318) was a 1-year, open-label, multicenter, prospective study of patients with nondialysis-dependent CKD, anemia and iron deficiency randomized (1:1:2) to IV ferric carboxymaltose (FCM), targeting higher (400-600 µg/L) or lower (100-200 µg/L) ferritin, or oral iron. A post hoc analysis of adverse event rates per 100 patient-years was performed to assess the safety of FCM versus oral iron over an extended period. Results: The safety population included 616 patients. The incidence of one or more adverse events was 91.0, 100.0 and 105.0 per 100 patient-years in the high ferritin FCM, low ferritin FCM and oral iron groups, respectively. The incidence of adverse events with a suspected relation to study drug was 15.9, 17.8 and 36.7 per 100 patient-years in the three groups; for serious adverse events, the incidence was 28.2, 27.9 and 24.3 per 100 patient-years. The incidence of cardiac disorders and infections was similar between groups. At least one ferritin level ≥800 µg/L occurred in 26.6% of high ferritin FCM patients, with no associated increase in adverse events. No patient with ferritin ≥800 µg/L discontinued the study drug due to adverse events. Estimated glomerular filtration rate remained the stable in all groups. Conclusions: These results further support the conclusion that correction of iron deficiency anemia with IV FCM is safe in patients with nondialysis-dependent CKD

The cerebellum and anticipatory actions: computational modeling, robotics and neuroprosthetic studies

Animals excel in skilled motor behavior, especially when compared to arti cial systems. Several adaptive and predictive motor control frameworks have been proposed to account for such performance, but the underlying biological implementation remains elusive. In vertebrates, the cerebellum is the most promising candidate locus where adaptive and predictive motor control primitives might be implemented. Indeed, several motor learning paradigms indicate that the cerebellum can drive anticipatory and well-timed coordinated motor actions. The most widely employed of such paradigms, classical conditioning of the eyelid re ex (eyeblink conditioning), has a well-de ned circuitry blueprint as well as known input and output pathways. However, the underlying physiological mechanisms are not fully understood, and neither is it clear whether cerebellar function in eyeblink conditioning can be extrapolated to more general anticipatory actions. This dissertation addresses these two questions relying on computational, robotic and neuro-prosthetic approaches, following the hypothesis that the cerebellum, working as an adaptive feedforward lter, interacts with a reactive layer of feedback control. First, we show that GABAergic slow inhibitory currents provide a biologically grounded mechanism accounting for the representation of time in the cerebellar cortex. Based on such assumption, we build a computational model of the cerebellum that successfully controls robots in avoidance learning tasks and replaces the learning function of an inactivated rat cerebellum using a neuro-prosthetic implantation. Thus, we provide a biologically grounded explanation of the mechanisms underlying the acquisition of anticipatory responses by the cerebellum, that is fully functional in both robotic and neuro-prosthetic scenarios. Altogether, this work advances our understanding of the mechanisms at the basis of coordinated motor control in animals, and through this, it takes a step towards developing equivalent motor capabilities in arti cial systems.Els animals assoleixen unes habilitats motores que superen de llarg la dels sistemes arti cials actuals. S'ha proposat que diferents marcs de control adaptatiu i predictiu estan a la base d'aquest acompliment, pero la seva implementació biològica roman desconeguda. En el cas dels vertebrats, és el cerèvel l'estructura cerebral on més probablement s'implementen aquestes primitives adaptatives i predictives. De fet, multiples paradigmes d'aprenentatge motor indiquen que el cerevel es capaç de controlar l'adquisició de accions motores anticipatòries i executar-les amb gran precisió temporal. El paradigma més estudiat, el condicionament clássic del parpelleig, té una anatomia ben de nida així com també un circuits d'entrada i sortida coneguts. Tanmateix, els mecanismes a la base d'aquest tipus d'aprenentatge no es coneixen com tampoc es sap si la funció del cérevel al condicionament del parpelleig es pot generalitzar a altres tipus d'accions anticipatòries. Aquesta disertació adreça aquestes dues qüestion i ho fa mitjaçant estudis computacionals, robotics i neuroprost ètics, on apliquem l'hipòtesi que el cerevel actúa com a un ltre adaptatiu que complementa la funció d'una capa de control reactiva. En primer lloc, demostrem que les corrents inhibitories per versament proporcionen un sustrat siològic per a la represtació del temps en l'escorça del cerevel. Basant-nos en aquesta assumpció, desarrotlem un model computacional que es capaç de controlar un robot en un tasca de prevenció de colisions i que, implementat en un implant neuro-prostètic, també pot reemplaçar funcionalment el cerevel farmacologicament inactivat d'una rata. D'aquesta manera, donem un explicació biologicament plausible per als mecanismes que permeten l'aquisició de respostes anticipatories al cerevel, que a més a més es funcional tant en l'àmbit de la robòtica com en el de les neuro-pròtesis. Tot plegat, aquesta feina avança el coneixement relatiu als mecanismes que a la base del control motor en animals, i mitjançant això dòna un pas vers el desenvolupament de sistemes arti cials amb capacitats equivalents

Apprendimento morfologico, relazioni base-derivato e topologie paradigmatiche. Evidenze psico-computazionali a confronto

No abstract available.Il presente lavoro ? volto a esplorare alcune dinamiche acquisizionali relative ai processi di maturazione della competenza morfologica in apprendenti bambini. In quest\u27ottica, sono riportate due differenti simulazioni computazionali dei processi di apprendimento della morfologia flessiva in Italiano e in Inglese. La prima simulazione, propria di un quadro connessionista classico, d? conto in modo inadeguato delle differenti dinamiche dell\u27apprendimento di alcune forme flesse verbali in inglese e italiano. La seconda simulazione, basata su un modello di memorie associative \u27a cascata\u27 addestrate tramite protocollo non-supervisionato, rende conto in maniera non banale del paradosso acquisizionale, confermato su base inter-linguistica da un recente studio di Dressler e colleghi (Bittner et al., 2003), secondo cui sistemi flessivi pi? complessi e completi sono appresi con maggiore facilit? di sistemi flessivi pi? semplici ed estesamente sincretiche