bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long-chain alkyl-substituted gentisic acid and benzoquinone derivatives from the root of Micronychia tsiramiramy (Anacardiaceae)
Authors: Razakarivony Andrianambinina A. , Lenta Bruno N. , Andriamihaja Bakolinirina , Michalek Carmela , Razanamahefa Bakonirina , Razafimahefa Dorothée R. , Rakotondramanga Maonja Finaritra , Randrianasolo Rivoarison , Lannang Alain Méli , Randriamiaramisaina Ralinandrianina , Boyom Fekam F. , Rosenthal Philip J. , Sewald Norbert 
Published: March 2016

Abstract
A new gentisic acid derivative named micronyc acid (1) and a new 1,4-benzoquinone derivative named micronone (2) have been isolated from the root of Micronychia tsiramiramy together with the known compounds gallic acid (3), methyl gallate (4), moronic acid (5), masticadienolic acid (6), and masticadienediol (7). The structures of 1 and 2 were established using MS and NMR. Compound 1 was tested for antiplasmodial activity in vitro against the chloroquine-resistant strain Plasmodium falciparum W2 and displayed moderate antiplasmodial activity in vitro with an IC50 value of 25.6 μ
m. Compounds 1 and its acetyl derivative 1a were also tested for their cytotoxicity against the human cervix carcinoma cell line KB-3-1 and still showed moderate activity.
Hydroalumination and hydrogallation of an aryl-chloro-dialkynylsilane: Si–Cl bond activation by intramolecular Al–Cl and Ga–Cl interactions
Authors: Uhl Werner , Kappelt Benedikt , Kappelt Frederik , Bohnemann Jörg , Layh Marcus 
Published: March 2016

Abstract
The chlorine functionalized dialkynylsilane (4-
t
Bu-C6H4)(Cl)Si(C≡C-
t
Bu)2 (3) reacted with equimolar quantities of H–Al
t
Bu2 or H–Ga
t
Bu2 by hydrometallation of a C≡C triple bond and formation of mixed alkenyl-alkynylsilanes (4 and 5) in which the Si and Lewis acidic metal atoms adopt geminal positions at the α-C atoms of the alkenyl groups. Intramolecular M···Cl interactions (M=Al, Ga) afforded four-membered SiCMCl heterocycles which in comparison with 3 had significantly lengthened Si–Cl bonds. Dual hydrometallation of 3 was only observed for H–Ga
t
Bu2. One Ga atom of the product (6) was coordinated by the silicon-bound Cl atom, while the second one showed an interaction with the aromatic ring of the tert-butyl-phenyl group. Treatment of the aluminium compound 4 with two equivalents of H–Ga
t
Bu2 afforded a Si–H bond by Cl-H exchange and release of Cl–Al
t
Bu2. The resulting silane (7) has the Si atom and two Ga atoms bridged by the α-C atoms of two vinyl groups. The specific functionality of 4 caused a remarkable reactivity. Phenyl isocyanate reacted by the formal insertion into the Al–C(vinyl) and the activated Si–Cl bonds and resulted in the formation of a C–C bond. The product (8) has a SiC2N heterocycle with an Si–N bond and exocyclic C=C and C=O double bonds. The keto group is coordinated to a Cl–Al
t
Bu2 molecule, which was formed by the shift of the Cl atom from silicon to aluminium.
Different Roles of Direct and Indirect Frontoparietal Pathways for Individual Working Memory Capacity
Authors: Ekman Matthias , Fiebach Christian J. , Melzer Corina , Tittgemeyer Marc , Derrfuss Jan 
Published: March 2016

The ability to temporarily store and manipulate information in working memory is a hallmark of human intelligence and differs considerably across individuals, but the structural brain correlates underlying these differences in working memory capacity (WMC) are only poorly understood. In two separate studies, diffusion MRI data and WMC scores were collected for 70 and 109 healthy individuals. Using a combination of probabilistic tractography and network analysis of the white matter tracts, we examined whether structural brain network properties were predictive of individual WMC. Converging evidence from both studies showed that lateral prefrontal cortex and posterior parietal cortex of high-capacity individuals are more densely connected compared with low-capacity individuals. Importantly, our network approach was further able to dissociate putative functional roles associated with two different pathways connecting frontal and parietal regions: a corticocortical pathway and a subcortical pathway. In Study 1, where participants were required to maintain and update working memory items, the connectivity of the direct and indirect pathway was predictive of WMC. In contrast, in Study 2, where participants were required to maintain working memory items without updating, only the connectivity of the direct pathway was predictive of individual WMC. Our results suggest an important dissociation in the circuitry connecting frontal and parietal regions, where direct frontoparietal connections might support storage and maintenance, whereas subcortically mediated connections support the flexible updating of working memory content.SIGNIFICANCE STATEMENTUsing diffusion MRI and network analysis, we found that the capacity of healthy individuals to temporally maintain information in working memory was related to a cortical pathway connecting frontal and parietal regions. The updating of working memory content, on the other hand, additionally involved a subcortical pathway connecting frontal and parietal regions via thalamus and basal ganglia. These results suggest that the two anatomical pathways serve different functional roles for working memory.
Human Choice Strategy Varies with Anatomical Projections from Ventromedial Prefrontal Cortex to Medial Striatum
Authors: Piray Payam , Toni Ivan , Cools Roshan 
Published: March 2016

Two distinct systems, goal-directed and habitual, support decision making. It has recently been hypothesized that this distinction may arise from two computational mechanisms, model-based and model-free reinforcement learning, neuronally implemented in frontostriatal circuits involved in learning and behavioral control. Here, we test whether the relative strength of anatomical connectivity within frontostriatal circuits accounts for variation in human individuals' reliance on model-based and model-free control. This hypothesis was tested by combining diffusion tensor imaging with a multistep decision task known to distinguish model-based and model-free control in humans. We found large interindividual differences in the degree of model-based control, and those differences are predicted by the structural integrity of white-matter tracts from the ventromedial prefrontal cortex to the medial striatum. Furthermore, an analysis based on masking out of bottom-up tracts suggests that this effect is driven by top-down influences from ventromedial prefrontal cortex to medial striatum. Our findings indicate that individuals with stronger afferences from the ventromedial prefrontal cortex to the medial striatum are more likely to rely on a model-based strategy to control their instrumental actions. These findings suggest a mechanism for instrumental action control through which medial striatum determines, at least partly, the relative contribution of model-based and model-free systems during decision-making according to top-down model-based information from the ventromedial prefrontal cortex. These findings have important implications for understanding the neural circuitry that might be susceptible to pathological computational processes in impulsive/compulsive psychiatric disorders.SIGNIFICANCE STATEMENTScholars from several disciplines have long been interested in the neural mechanisms of decision-making. An influential suggestion has structured decision-making into a flexible but expensive model-based system, and a more rapid but also more rigid model-free system. Here, we show that anatomical properties of the connections between frontal and striatal regions predict the use of a model-based system when individuals make decisions. Individuals with stronger top-down connectivity from the ventromedial prefrontal cortex to the medial striatum were more likely to rely on a model-based strategy during decision-making, suggesting that the ventromedial prefrontal cortex biases a striatal balance between model-based and model-free control. These findings qualify the neural implementation of decision-making computations and open the way for understanding decision-making pathologies.
Absence of Prenatal Forebrain Defects in the Dp(16)1Yey/+ Mouse Model of Down Syndrome
Authors: Goodliffe Joseph W. , Olmos-Serrano Jose Luis , Aziz Nadine M. , Pennings Jeroen L.A. , Guedj Faycal , Bianchi Diana W. , Haydar Tarik F. 
Published: March 2016

Studies in humans with Down syndrome (DS) show that alterations in fetal brain development are followed by postnatal deficits in neuronal numbers, synaptic plasticity, and cognitive and motor function. This same progression is replicated in several mouse models of DS. Dp(16)1Yey/+ (hereafter called Dp16) is a recently developed mouse model of DS in which the entire region of mouse chromosome 16 that is homologous to human chromosome 21 has been triplicated. As such, Dp16 mice may more closely reproduce neurodevelopmental changes occurring in humans with DS. Here, we present the first comprehensive cellular and behavioral study of the Dp16 forebrain from embryonic to adult stages. Unexpectedly, our results demonstrate that Dp16 mice do not have prenatal brain defects previously reported in human fetal neocortex and in the developing forebrains of other mouse models, including microcephaly, reduced neurogenesis, and abnormal cell proliferation. Nevertheless, we found impairments in postnatal developmental milestones, fewer inhibitory forebrain neurons, and deficits in motor and cognitive performance in Dp16 mice. Therefore, although this new model does not express prenatal morphological phenotypes associated with DS, abnormalities in the postnatal period appear sufficient to produce significant cognitive deficits in Dp16.SIGNIFICANCE STATEMENTDown syndrome (DS) leads to intellectual disability. Several mouse models have increased our understanding of the neuropathology of DS and are currently being used to test therapeutic strategies. A new mouse model that contains an expanded number of DS-related genes, known as Dp(16)1Yey/+ (Dp16), has been generated recently. We sought to determine whether the extended triplication creates a better phenocopy of DS-related brain pathologies. We measured embryonic development, forebrain maturation, and perinatal/adult behavior and revealed an absence of prenatal phenotypes in Dp16 fetal brain, but specific cellular and behavioral deficits after the first 2 postnatal weeks. These results uncover important differences in prenatal phenotype between Dp16 animals and humans with DS and other DS mouse models.
Pitch-Responsive Cortical Regions in Congenital Amusia
Authors: Norman-Haignere Sam V. , Albouy Philippe , Caclin Anne , McDermott Josh H. , Kanwisher Nancy G. , Tillmann Barbara 
Published: March 2016

Congenital amusia is a lifelong deficit in music perception thought to reflect an underlying impairment in the perception and memory of pitch. The neural basis of amusic impairments is actively debated. Some prior studies have suggested that amusia stems from impaired connectivity between auditory and frontal cortex. However, it remains possible that impairments in pitch coding within auditory cortex also contribute to the disorder, in part because prior studies have not measured responses from the cortical regions most implicated in pitch perception in normal individuals. We addressed this question by measuring fMRI responses in 11 subjects with amusia and 11 age- and education-matched controls to a stimulus contrast that reliably identifies pitch-responsive regions in normal individuals: harmonic tones versus frequency-matched noise. Our findings demonstrate that amusic individuals with a substantial pitch perception deficit exhibit clusters of pitch-responsive voxels that are comparable in extent, selectivity, and anatomical location to those of control participants. We discuss possible explanations for why amusics might be impaired at perceiving pitch relations despite exhibiting normal fMRI responses to pitch in their auditory cortex: (1) individual neurons within the pitch-responsive region might exhibit abnormal tuning or temporal coding not detectable with fMRI, (2) anatomical tracts that link pitch-responsive regions to other brain areas (e.g., frontal cortex) might be altered, and (3) cortical regions outside of pitch-responsive cortex might be abnormal. The ability to identify pitch-responsive regions in individual amusic subjects will make it possible to ask more precise questions about their role in amusia in future work.SIGNIFICANCE STATEMENTThe neural causes of congenital amusia, a lifelong deficit in pitch and music perception, are not fully understood. We tested the hypothesis that amusia is due to abnormalities in brain regions that respond selectively to sounds with a pitch in normal listeners. Surprisingly, amusic individuals exhibited pitch-responsive regions that were similar to normal-hearing controls in extent, selectivity, and anatomical location. We discuss how our results inform current debates on the neural basis of amusia and how the ability to identify pitch-responsive regions in amusic subjects will make it possible to ask more precise questions about their role in amusic deficits.
Attention Strongly Modulates Reliability of Neural Responses to Naturalistic Narrative Stimuli
Authors: Ki Jason J. , Kelly Simon P. , Parra Lucas C. 
Published: March 2016

Attentional engagement is a major determinant of how effectively we gather information through our senses. Alongside the sheer growth in the amount and variety of information content that we are presented with through modern media, there is increased variability in the degree to which we “absorb” that information. Traditional research on attention has illuminated the basic principles of sensory selection to isolated features or locations, but it provides little insight into the neural underpinnings of our attentional engagement with modern naturalistic content. Here, we show in human subjects that the reliability of an individual's neural responses with respect to a larger group provides a highly robust index of the level of attentional engagement with a naturalistic narrative stimulus. Specifically, fast electroencephalographic evoked responses were more strongly correlated across subjects when naturally attending to auditory or audiovisual narratives than when attention was directed inward to a mental arithmetic task during stimulus presentation. This effect was strongest for audiovisual stimuli with a cohesive narrative and greatly reduced for speech stimuli lacking meaning. For compelling audiovisual narratives, the effect is remarkably strong, allowing perfect discrimination between attentional state across individuals. Control experiments rule out possible confounds related to altered eye movement trajectories or order of presentation. We conclude that reliability of evoked activity reproduced across subjects viewing the same movie is highly sensitive to the attentional state of the viewer and listener, which is aided by a cohesive narrative.SIGNIFICANCE STATEMENTModern technology has brought about a monumental surge in the availability of information. There is a pressing need for ways to measure and characterize attentional engagement and understand the causes of its waxing and waning in natural settings. The present study demonstrates that the degree of an individual's attentional engagement with naturalistic narrative stimuli is strongly predicted by the degree of similarity of his/her neural responses to a wider group. The effect is so strong that it enables perfect classification of attentional state across individuals for some narrative stimuli. As modern information content continues to diversify, such direct neural metrics will become increasingly important to manage and evaluate its effects on both the healthy and disordered human brain.
Reactivation of Reward-Related Patterns from Single Past Episodes Supports Memory-Based Decision Making
Authors: Wimmer G. Elliott , Büchel Christian 
Published: March 2016

Rewarding experiences exert a strong influence on later decision making. While decades of neuroscience research have shown how reinforcement gradually shapes preferences, decisions are often influenced by single past experiences. Surprisingly, relatively little is known about the influence of single learning episodes. Although recent work has proposed a role for episodes in decision making, it is largely unknown whether and how episodic experiences contribute to value-based decision making and how the values of single episodes are represented in the brain. In multiple behavioral experiments and an fMRI experiment, we tested whether and how rewarding episodes could support later decision making. Participants experienced episodes of high reward or low reward in conjunction with incidental, trial-unique neutral pictures. In a surprise test phase, we found that participants could indeed remember the associated level of reward, as evidenced by accurate source memory for value and preferences to re-engage with rewarded objects. Further, in a separate experiment, we found that high-reward objects shown as primes before a gambling task increased financial risk taking. Neurally, re-exposure to objects in the test phase led to significant reactivation of reward-related patterns. Importantly, individual variability in the strength of reactivation predicted value memory performance. Our results provide a novel demonstration that affect-related neural patterns are reactivated during later experience. Reactivation of value information represents a mechanism by which memory can guide decision making.SIGNIFICANCE STATEMENTRewarding and aversive experiences exert a strong influence on later decision making. Although much is known about how many associations between stimuli and reward shapes preferences, decisions are often supported by the value of single past experiences. Surprisingly, relatively little is known about how episodic experiences influence later behavior. In experiments using monetary reward anticipation in conjunction with incidental objects, we found that later behavior was indeed influenced by the value incidentally associated with objects. Critically, neural patterns related to reward experiences were re-expressed on later exposure and reactivation correlated with behavioral performance. Our results suggest a mechanism by which good and bad episodes from daily life can guide later decision making.
Cyclic AMP and Polyamines Overcome Inhibition by Myelin-Associated Glycoprotein through eIF5A-Mediated Increases in p35 Expression and Activation of Cdk5
Authors: He Huifang , Deng Kangwen , Siddiq Mustafa M. , Pyie Aung , Mellado Wilfredo , Hannila Sari S. , Filbin Marie T. 
Published: March 2016

Inhibitory molecules associated with CNS myelin, such as myelin-associated glycoprotein (MAG), represent major obstacles to axonal regeneration following CNS injury. Our laboratory has shown that elevating levels of intracellular cAMP, via application of the nonhydrolyzable analog dibutyryl cAMP (dbcAMP), can block the inhibitory effects of MAG and myelin. We have also shown that elevation of cAMP results in upregulation of arginase I and increased polyamine synthesis. Treatment with putrescine or spermidine blocks myelin-mediated inhibition of neurite outgrowth, but the mechanism underlying this effect has not yet been elucidated. Here we show that cyclin-dependent kinase 5 (Cdk5) is required for dbcAMP and putrescine to overcome MAG-mediated inhibition. The ability of dbcAMP and putrescine to overcome inhibition by MAG is abolished in the presence of roscovitine, a Cdk inhibitor that has greater selectivity for Cdk5, and expression of dominant negative Cdk5 abolishes the ability of dbcAMP or putrescine to enhance neurite outgrowth in the presence of MAG. Importantly, dbcAMP and putrescine increase expression of p35, the neuron-specific activator of Cdk5, and rat DRG neurons transduced with HSV overexpressing p35 can overcome inhibition by MAG. The upregulation of p35 by putrescine is also reflected in increased localization of p35 to neurites and growth cones. Last, we show that putrescine upregulates p35 expression by serving as a substrate for hypusine modification of eIF5A, and that this hypusination is necessary for putrescine's ability to overcome inhibition by MAG. Our findings reveal a previously unknown mechanism by which polyamines may encourage regeneration after CNS injury.SIGNIFICANCE STATEMENTThis study describes a novel mechanism for the activation of Cdk5 in neurons and a new role for Cdk5 in promoting axonal growth in the presence of myelin-associated inhibitors. We show that administration of the polyamine putrescine leads to hypusination of the translation initiation factor eIF5A, increased translation of p35, and activation of Cdk5 in cultured cerebellar neurons, and that each of these events is required for putrescine's ability to overcome inhibition by myelin-associated glycoprotein. These findings have implications for the development of new treatments for spinal cord and traumatic brain injury and provide new insight into the functions of eIF5A and Cdk5 in the nervous system.
Caracterización de la Cultura Organizacional en las MiPyMEs para Impulsar el Emprendimiento de alto Impacto en el Valle del Mezquital.
Authors: Linares Medina Irasema 
Published: March 2016

El emprendimiento de alto impacto, también llamado emprendimiento transformador (Lerner y Schoar, 2010), se distingue principalmente por buscar no solo una rentabilidad económica, sino lograr un verdadero impacto social, asegurando una contribución positiva con el medio ambiente. La caracterización de la cultura organizacional en las Micro, Pequeñas y Medianas Empresas (MiPyMEs) juega un papel preponderante para su desarrollo y consolidación, particularmente cuando se trata de promover en las MiPyMEs su alineamiento hacia el emprendimiento de alto impacto, ya que diversos estudios handemostrado que los rasgos de cultura organizacional son determinantes para el éxito o fracaso de las empresas. La presente propuesta, realizada con el apoyo del Instituto Nacional del Emprendedor, promueve el desarrollo de un estudio de cultura organizacional aplicado a una muestra de 80 MiPyMEs ubicadas en la región conocida como: Valle del Mezquital, en el Estado de Hidalgo, México; cuyo contexto socioeconómico y cultural es especial, ya que cuenta con más del 30% de población indí­gena que, además de contar con arraigadas costumbres heredadas de un pasado y presente de pobreza económica, presenta un singular fenómeno migratorio hacia los Estados Unidos.El propósito del estudio es determinar el tipo de cultura organizacional dominante en el marco del modelo de Cameron y Quinn (1999) e identificar, a través de la adecuación de un modelo de diagnóstico y de la aplicación de herramientas de recopilación de datos, cuáles son los elementos culturales que favorecen o limitan la existencia de emprendimientos de alto impacto en las MiPyMEs de esta región y, a partir de los resultados, proponer un conjunto de estrategias que permita impulsar este tipo de emprendimientos, contribuyendo así­ al desarrollo económico y social del Valle del Mezquital.