5,649 research outputs found

    Brain network alterations in Attention-Deficit and Hyperactivity Disorder: towards an integrative perspective based on systems neuroscience

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    Menci√≥n Internacional en el t√≠tulo de doctorAttention-Deficit and Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental disorders, affecting mainly the school-age population but also having a moderate prevalence rate into adulthood. It is characterized by symptoms of inattention, impulsivity, and hyperactivity improper for the patient‚Äôs age. However, this agedependent characterization of ADHD makes the diagnosis such a problematic issue: the maturation rate is different for each child, making the evaluation of what is age-proper a subjective and difficult question. All of this leads to the ubiquitous question of ADHD, namely, whether there is overdiagnosis of the disease or if it even exists. That is why studying the brain is crucial in ADHD, because finding effective biomarkers able to characterize the disease will allow us to diagnose it more accurately. Magnetic Resonance Imaging (MRI) is one of the most powerful and versatile tools for studying the brain, providing information about both its structure and activity. Traditional MRI studies have focused on analyzing properties of specific brain regions in terms of their shape (e.g., the volume of a structure) or their relation with a cognitive function (e.g., if a structure activates during object recognition), finding multiple alterations in ADHD [8]. However, these widespread regions that present abnormalities are connected between them and with other areas forming the brain network, and their alterations may indeed represent different parts of a more global phenomenon [8, 9]. There are four main neurobiological models that explain ADHD: the maturational lag hypothesis, the dual-pathway model, the Default Mode Network (DMN) interference hypothesis, and multinetwork models. The maturational lag hypothesis is based on ADHD diagnostic criteria and posits that the brain of people with this condition will resemble a younger one [10]. The dual-pathway model proposes two different processing streams for the main symptoms of ADHD: inattention is related to alterations in the corticostriatal executive circuits, while impulsivity/hyperactivity is associated with abnormalities in emotional processing [11, 12]. The DMN interference hypothesis posits that this functional network is not properly suppressed during goal-directed tasks, which is translated into intrusion of inner mental activity [13]. Finally, multinetwork models approach the neurobiology of people with ADHD as an alteration of multiple functional networks [14, 15]. All of these models have received substantial support from neuroimaging studies, which suggests that all of them are correct but incomplete descriptions of the brain profile of people with ADHD. The present dissertation aims to determine whether there is an alteration of the global brain organization in people with ADHD that may underlie the features that characterize the different neurobiological models of the disorder. For that, we will apply two different graph-theory methods based on systems science to the restingstate functional Magnetic Resonance Imaging data of adults and children with ADHD. The two proposed metrics are Stepwise Functional Connectivity (SFC) and Local and Distant Functional Connectivity (LFC and DFC). The first one measures the integration of information from sensory cortices to areas related to high-order cognitive functions, and in Study 1 [16], it will be applied to a sample of medication-na√Įve adults with ADHD. LFC and DFC study topological properties with physical distance restrictions, that is, the level of connectivity of each voxel with those around it or those far away. This method will be applied to a sample of children with ADHD in Study 2 [17] and the same sample of adults used in Study 1 in Study 3 [18]. Our results consist of alterations in widespread regions that overlap with most functional networks [19]. Specifically, in adults with ADHD, we observed a decrease in integration in the DMN that locally affects the Posterior Cingulate Cortex and its functional connectivity with the medial Prefrontal Cortex. Additionally, the integration of sensory information in these areas was also found to be reduced in the same sample. The integration of the DMN and its development into cortical hubs is a crucial process in the maturation of the brain [20], which relates this finding with a maturational lag. In both children and adults with ADHD, we also observed a lack of segregation between the DMN, the Ventral Attentional Network, and the Frontoparietal Network in a frontal area of the brain. The developmental trajectory of this area consists of the differentiation of three regions, each of them pertaining to one of these networks [21], and thus, it is a sign of brain immaturity. Also, overconnectivity (lack of segregation) between these networks underlies the DMN interference hypothesis and is indeed a multinetwork alteration [14, 22]. We also found abnormalities in the Visual Network in the form of increased integration of information in these areas while decreased local functional integration of the region, which reflects a behavior more typical of associative than sensory cortices [23, 24]. Finally, local connectivity of sensorimotor cortices presents different maturation trends between ADHD and controls while predicting ADHD symptomatology in all of them. In conclusion, our results suggest that for understanding ADHD, we cannot focus just on a few areas related to high-order cognitive functions, but the whole brain functional network is compromised. This goes in line with a recent meta-analysis [8] that was unable to find convergence in specific regions abnormalities and proposed an analysis based on network interactions. Altogether, this dissertation reflects the need to approach ADHD from a systems neuroscience perspective that encompasses all the currently available models instead of proposing alternative reductionist ones.Programa de Doctorado en Ciencia y Tecnolog√≠a Biom√©dica por la Universidad Carlos III de MadridPresidente: Juan Domingo Gispert L√≥pez.- Secretario: Carles Soriano Mas.- Vocal: √ďscar Esteban Sanz-Drangue

    Estimació basada en CNN de la cinemàtica de les extremitats inferiors durant la neurorrehabilitació assistida per robot.

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    [ES] El sistema VEMOTION, desarrollado por Reactive Robotics GmbH, consiste en un sistema rob√≥tico de rehabilitaci√≥n de pacientes con problemas de movilidad. El objetivo principal de este estudio es capturar los datos de movimiento del humano para desarrollar un modelo cinem√°tico basado √ļnicamente en la informaci√≥n de los sensores del dispositivo rob√≥tico, utilizando un enfoque basado en redes neuronales convolucionales.[EN] The VEMOTION system, developed by Reactive Robotics GmbH, consists of a robotic system-based rehabilitation of patients with mobility impairments. The main objective of this study is to capture the motion data of the human to develop a kinematic model based only on the sensor information of the robotic device, using a CNN-based approach.Vidal Solano, L. (2022). CNN-Based estimation of lower extremity kinematics during robot-based neurorehabilitation. Universitat Polit√®cnica de Val√®ncia. http://hdl.handle.net/10251/19044

    Inertial Load Compensation by a Model Spinal Circuit During Single Joint Movement

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    Office of Naval Research (N00014-92-J-1309); CONACYT (Mexico) (63462

    Inuitus inuitan: Suetonio, Racine, Purceil.

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    Sin resume

    Lo augusteo en la elegía romana de la época de Augusto: Tibulo y Propercio

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    En la introducci√≥n a este art√≠culo se revisa el concepto de ¬ęliteratura augustea¬Ľ y se examinan las relaciones de Augusto con los poetas, y espec√≠ficamente el problema de hasta qu√© punto Augusto, en su ejercicio del patronazgo, coart√≥ o condicion√≥ la libertad creativa de los poetas de su √©poca. A continuaci√≥n se hace referencia a las diversas maneras de comportarse de los poetas de la √©poca de Augusto frente a la ideolog√≠a y el programa agusteos, un comportamiento que oscila de la adhesi√≥n a la indiferencia. La parte central del trabajo considera desde esa perspectiva la eleg√≠a er√≥tica romana, concretamente Tibulo y Propercio. Se observa de qu√© manera los temas y valores augusteos, esencialmente p√ļblicos e institucionales, son aceptados y transformados como elementos de un mundo po√©tico tan centrado en el yo del poeta, en su subjetividad y en el intimismo de sus relaciones, como es el mundo de los poetas eleg√≠acos

    Prototype of speech translation system for audio effective communication

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    The present document exposes the development of a prototype of translation system as a Thesis Project. It consists basically on the capture of a flow of voice from the emitter, integrating advanced technologies of voice recognition, instantaneous translation and communication over the internet protocol RTP/RTCP (Real time Transport Protocol) to send information in real-time to the receiver. This prototype doesn't transmit image, it only boards the audio stage. Finally, the project besides embracing a problem of personal communications, tries to contribute to the development of activities related with the speech recognition, motivating new investigations and advances on the area.Applications in Artificial Intelligence - Language ProcessingRed de Universidades con Carreras en Inform√°tica (RedUNCI

    Field Study of Electrochemical Disinfection of Municipal Wastewater

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    Research on electrochemical disinfection of municipal wastewater has been conducted at the University of New Orleans using a continuous flow electrochemical reactor connected to a direct current (DC) power supply changing its polarity and varying the electrode distance. Bacterial inactivation and chlorine production were the main parameters that were recorded. After months of research, it was determined that the electrochemical disinfection reactor is efficient and has a great potential for the future. There is no need to use chlorine and it has low operation costs. The following design recommendations for an electrochemical disinfection unit were given: A detention time of 5 +- 0.3 minutes A minimum volumetric current density of 1000 amps/m3 A minimum detention current density of 80 amps.hr/m3 The combination of the three recommended design values yielded excellent disinfection efficiencies and low chlorine production

    Bilateral and Unilateral Asymmetries of Strength and Flexibility in Young Elite Sailors: Windsurfing, Optimist and Laser Classes

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    In sport sailing, performance is related to the sailor’s ability to maintain the stability of the boat, and the boat class determines the variables involved in such ability. In monohull-type vessels, such as the Optimist and Laser classes, the flexibility of the hip joint is a key performance factor. In the Windsurfing class, performance is determined by the strength of the flexors of the fingers and elbows. The performance of the sailor may be a ected by asymmetries in the strength and flexibility of the muscles and joints involved in technical actions. The objective of this study was to evaluate asymmetries in strength and flexibility in young sailors. Thirty-three young sailors (ten girls) from the Windsurfing, Optimist and Laser classes were assessed for manual strength and flexibility, by dynamometry and straight leg lift tests, respectively. The symmetry index and the functional asymmetry of compression force were calculated. The results showed no di erences between sailors according to gender. The sailors of the Laser class obtained the highest levels of manual strength, whereas those of the Windsurfing class showed the highest flexibility levels. The girls’ group andWindsurfing class had the highest percentage of sailors with strength asymmetry, whereas, the sailors of the Optimist class presented a greater percentage of asymmetry in flexibility. There were no di erences in upper limb strength and lower limb flexibility between the dominant and non-dominant sides

    Una clase de matem√°TICas

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    Se trata de exponer c√≥mo se puede impartir clase de matem√°ticas aprovechando las TICs de las que dispone el profesorado y el alumnado. Entre estas tenemos la tableta digitalizadora que nos facilita el uso de las dem√°s, que aparte de conseguir que la clase se pueda impartir siempre de cara al alumnado, cambia el sistema tradicional de volverse para la pizarra para escribir, a de nuevo volverse para dirigirnos al alumnado; adem√°s de esto, si deseamos se√Īalar algo escrito o reforzar lo explicado, habr√≠a que desconectar otra vez
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