bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid Electrophysiological Brain Responses are Influenced by Both Valence and Magnitude of Monetary Rewards
Authors: Goyer Julia P. , Woldorff Marty G. , Huettel Scott A. 
Published: April 2008

Abstract
Negative outcomes, as identified from external feedback, cause a short-latency negative deflection in the event-related potential (ERP) waveform over medial frontal electrode sites. This brain response, which has been called an “error related negativity” (ERN) or “medial frontal negativity” (MFN), may reflect a coarse evaluation of performance outcomes, such as the valence of a reward within a monetary gambling task. Yet, for feedback to lead to the adaptive control of behavior, other information concerning reward outcomes besides experienced valence may also be important. Here, we used a gambling task in which subjects chose between two options that could vary in both outcome valence (gain or loss) and outcome magnitude (larger or smaller). We measured changes in brain ERP responses associated with the presentation of the outcomes. We found, as shown in prior studies, that valence of the chosen outcome has an early effect upon frontal ERPs, with maximal difference observed at ∼250 msec. However, our results demonstrated that the early ERP responses to outcome feedback were driven not just by valence but by the combination of valence and magnitude for both chosen and unchosen options. Beginning even earlier, at around 150 msec, responses to high-consequence outcomes resulted in a greater, more centrally distributed, positive potential than those involving low-consequence outcomes, independent of valence. Furthermore, the amplitude of these early effects was significantly modulated by the sequence of outcomes in previous trials. These results indicate that early evaluation of feedback goes beyond simple identification of valence—it involves the consideration of multiple factors, including outcome magnitude, context of unchosen options, and prior history.
Gamma Band Synchronization and the Formation of Representations in Visual Word Processing: Evidence from Repetition and Homophone Priming
Authors: Matsumoto Atsushi , Iidaka Tetsuya 
Published: April 2008

Abstract
The formation of an object's cortical representation seems to rely on synchronized neuronal activity within the gamma band frequency range (gamma band activity [GBA]). In this study, we investigated whether electroencephalogram (EEG) GBA, and its phase synchronization between electrodes, is necessary for the formation of nonobject higher-order cognitive representations, using both repetition and homophone priming tasks. In a repetition priming task, the formation of orthographic, phonological, and semantic representations is promoted by a prime word, whereas in the homophone priming task, the formation of only phonological representations is promoted. In the present study, the lexical processing of a target word induced GBA. In the repetition priming task, induced GBA and phase synchronization were decreased by presentation of the prime word (i.e., a repetition suppression effect) within both 200–300 msec and 400–500 msec time windows. In the homophone priming task, the repetition suppression effect was observed only within the 400–500 msec time window. The fact that repetition suppression effects were found in both priming tasks indicates that GBA and phase synchronization are necessary for the formation of phonological and semantic representations of a word. These results also suggest that formation of orthographic and higher-order cognitive representations occurred over different time courses.
Neural Activity within Area V1 Reflects Unconscious Visual Performance in a Case of Blindsight
Authors: Radoeva Petya D. , Prasad Sashank , Brainard David H. , Aguirre Geoffrey K. 
Published: April 2008

AbstractAlthough lesions of the striate (V1) cortex disrupt conscious vision, patients can demonstrate surprising residual abilities within their affected visual field, a phenomenon termed blindsight. The relative contribution of spared “islands” of functioning striate cortex to residual vision, versus subcortical pathways to extrastriate areas, has implications for the role of early visual areas in visual awareness and performance. Here we describe the behavioral and neural features of residual cortical function in Patient M.C., who sustained a posterior cerebral artery stroke at the age of 15 years. Within her impaired visual field, we found preserved visual abilities characteristic of blindsight, including superior detection of motion, and above-chance discrimination of shape, color, and motion direction. Functional magnetic resonance imaging demonstrated a retinotopically organized representation of M.C.'s blind visual field within the lesioned occipital lobe, specifically within area V1. The incongruity of a well-organized cortex and M.C.'s markedly impaired vision was resolved by measurement of functional responses within her damaged occipital lobe. Attenuated neural contrast-response functions were found to correlate with M.C.'s impaired psychophysical performance. These results demonstrate that the behavioral features of blindsight may arise in the presence of residual striate responses that are spatially organized and sensitive to contrast variation.
How Does Reward Expectation Influence Cognition in the Human Brain?
Authors: Rowe James B. , Eckstein Doris , Braver Todd , Owen Adrian M. 
Published: April 2008

Abstract
The prospect of reward changes how we think and behave. We investigated how this occurs in the brain using a novel continuous performance task in which fluctuating reward expectations biased cognitive processes between competing spatial and verbal tasks. Critically, effects of reward expectancy could be distinguished from induced changes in task-related networks. Behavioral data confirm specific bias toward a reward-relevant modality. Increased reward expectation improves reaction time and accuracy in the relevant dimension while reducing sensitivity to modulations of stimuli characteristics in the irrelevant dimension. Analysis of functional magnetic resonance imaging data shows that the proximity to reward over successive trials is associated with increased activity of the medial frontal cortex regardless of the modality. However, there are modality-specific changes in brain activity in the lateral frontal, parietal, and temporal cortex. Analysis of effective connectivity suggests that reward expectancy enhances coupling in both early visual pathways and within the prefrontal cortex. These distributed changes in task-related cortical networks arise from subjects' representations of future events and likelihood of reward.
Neural Indicators of Inference Processes in Text Comprehension: An Event-related Functional Magnetic Resonance Imaging Study
Authors: Friese Uwe , Rutschmann Roland , Raabe Markus , Schmalhofer Franz 
Published: April 2008

Abstract
During language comprehension, readers or listeners routinely infer information that has not been stated literally in a given text or utterance in order to construct a coherent mental representation (situation model). We used a verification task in a behavioral study and in an event-related functional magnetic resonance imaging (fMRI) experiment to investigate the inference construction process. After having read sentences that mention the outcome of an event explicitly, implicitly, or not at all, participants verified the plausibility of short statements with respect to the context of the just read sentence. The results of the behavioral study established the verification task as a valid method for studying inferences. In the fMRI study, the dorsomedial prefrontal cortex was the most prominent area that was involved in the processing of inference statements. Regions in the left and right temporal lobes were associated with comparison processes that are based on the propositional representations of context sentence and test statements. The results are discussed with respect to levels of representations and the memory systems that underlie the verification process in the different sentence conditions.
The Neural and Computational Basis of Controlled Speed-Accuracy Tradeoff during Task Performance
Authors: van Veen Vincent , Krug Marie K. , Carter Cameron S. 
Published: April 2008

Abstract
People are capable, at will, of trading speed for accuracy when performing a task; they can focus on performing accurately at the cost of being slow, or emphasize speed at the cost of decreased accuracy. Here, we used functional magnetic resonance imaging to investigate the neural correlates of this ability. We show increased baseline activity during speed emphasis in a network of areas related to response preparation and execution, including the premotor areas of the frontal lobe, the basal ganglia, the thalamus, and the dorsolateral prefrontal and left parietal cortices. Furthermore, speed emphasis was associated with reduced transient response-related activation in several of these structures, suggesting that because of the greater baseline activity under speed emphasis, less activation is needed in these structures to reach response threshold, consistent with the assumptions of several computational theories. Moreover, we identify the dorsolateral prefrontal cortex as providing the top-down control signal that increases this baseline activity.
Sustained Activities and Retrieval in a Computational Model of the Perirhinal Cortex
Authors: Vitay Julien , Hamker Fred H. 
Published: April 2008

Abstract
The perirhinal cortex is involved not only in object recognition and novelty detection but also in multimodal integration, reward association, and visual working memory. We propose a computational model that focuses on the role of the perirhinal cortex in working memory, particularly with respect to sustained activities and memory retrieval. This model describes how different partial informations are integrated into assemblies of neurons that represent the identity of an object. Through dopaminergic modulation, the resulting clusters can retrieve the global information with recurrent interactions between neurons. Dopamine leads to sustained activities after stimulus disappearance that form the basis of the involvement of the perirhinal cortex in visual working memory processes. The information carried by a cluster can also be retrieved by a partial thalamic or prefrontal stimulation. Thus, we suggest that areas involved in planning and memory coordination encode a pointer to access the detailed information encoded in the associative cortex such as the perirhinal cortex.
Reproduction and sexual dimorphism of Lepidophyma sylvaticum (Squamata: Xantusiidae), a tropical night lizard from Tlanchinol, Hidalgo, Mexico
Authors: Ramírez-Bautista Aurelio , Vitt Laurie , Ramírez-Hernández Alejandra , Mendoza Quijano Fernando , Smith Geoffrey 
Published: April 2008

AbstractWe studied reproductive characteristics of the night lizard, Lepidophyma sylvaticum (Xantusiidae) from cloud forest in Tlanchinol, Hidalgo, Mexico. Males reached sexual maturity at a snout-vent length (SVL) of 55 mm, and females reached sexual maturity at a SVL of 56 mm. Males and females were not sexually dimorphic in SVL, but males had significantly larger heads and limbs than females. Reproduction in males and females was seasonal. Testicular mass increased in July and August, reaching maximum size in September. Minimum testes size occurred in March. Follicles of females began to increase in size in September when vitellogenesis was observed. Follicles in some females increased in mass during January-March, whereas other females ovulated during that period. Late embryonic stages (35-40) were observed in July with parturition likely occurring in July and August, coincident with maximum rainfall. Litter size averaged 4.7 ± 0 .4 neonates, and was not correlated with female size. Similarities in reproductive characteristics between L. sylvaticum and other xantusiids (viviparity, long gestation period) suggest that some reproductive characteristics have a historical origin.
A new species of the diurnal gekkonid genus Pristurus Rüppell, 1835 from the Red Sea island Hanish al-Kabir, Yemen
Authors: Rösler Herbert , Böhme Wolfgang , Köhler Jörn 
Published: April 2008

AbstractWe describe a new species of gecko of the genus Pristurus from the Yemenite Red Sea Island Hanish al-Kabir. It is a small species (snout-vent length less than 30 mm) of the genus, distinguished from its congeners by a unique combination of morphological characters. Superficially, it is most similar to P. rupestris, but differs mainly by a longer and narrower snout, by its strongly compressed tail, presence of a lateral caudal groove, by a tail crest present in both sexes, by a higher number of scales bordering infralabials and a higher midbody scale count. The new species is tentatively considered to represent an island endemic. Its possible origin is briefly discussed.
Basking in the Australian water dragon Physignathus lesueurii; why do alpha males not respond to operative temperatures in the same way as adults and sub-adults?
Authors: Avery Roger , Meek Roger 
Published: April 2008

AbstractObservations have been made on the behaviour of the Australian water dragon Physignathus lesueurii in southeast Australia. Physical models that explore the thermal environment at a similar spatial level as real lizards were related to ontogenetic changes in lizard behaviour. Current theory predicts that a heliotherm will bask in open locations to optimise heating rates in order to attain target body temperatures as quickly as possible. Movement to shaded or partially shaded areas then maintains thermal stability. Regression equations of basking intensity in relation to operative temperatures were employed to test this theory. The behaviour of adults, which were not alpha males, and sub adults was in agreement with the prediction, but the behaviour of alpha males was not: the regression coefficient did not differ significantly from 0. In general, sub adult lizards were more active and fed more often than larger lizards although this relationship changed with different times of the day. The results suggest differing costs for thermoregulation for different size classes, particularly in alpha males where territory defence has a key role.
Interspecific and intersexual variation in presacral vertebrae number in Podarcis bocagei and P. carbonelli
Authors: Carretero Miguel , Llorente Gustavo , Kaliontzopoulou Antigoni 
Published: April 2008

AbstractPodarcis bocagei and P. carbonelli are two closely related lizard species, endemic to the western Iberian Peninsula. Although genetic and morphological distinction between them is now well established, information on anatomical features is still very restricted. We studied presacral vertebrae number in both species, separately examining cervical and trunk vertebrae counts, in order to assess the interspecific and intersexual variation in these characters. There was no significant interspecific variation among lizards of the same sex for any of the vertebrae counts studied. However, important sexual variation existed, females presenting higher counts than males for both trunk and total presacral vertebrae, while males showed higher values of cervical vertebrae. Although our results lie within the known limits for other closely related species, they reveal that vertebrae number might present higher intraspecific variation than previously thought.
A multi-year and multi-site population study on the life history of Salamandrina perspicillata (Savi, 1821) (Amphibia, Urodela)
Authors: Utzeri Carlo , Angelini Claudio , Antonelli Damiano 
Published: April 2008

AbstractWe studied nine populations of Salamandrina perspicillata for two to nine years and described the life history variation among these population. Despite experiencing similar climatic conditions, populations differed in mean body size: populations using still water bodies for oviposition were larger body-sized than those using brooks. One semi-natural pond was used by particularly small individuals and was probably recently colonised. The mean body size of ovipositing females varied from year to year. Measurements of individuals in successive years showed that the tail grew more than the trunk and this differential growth increased with age. Females did not oviposit every year and, within a given population, the number of ovipositing females varied widely from year to year.
Negotiating 'Plainness' and Gender: Dancing and Apparel at Christian Weddings in Matabeleland, Zimbabwe, 1913-1944
Authors: Urban-Mead Wendy 
Published: April 2008

AbstractThis article analyzes the phenomena of dancing and wedding apparel in weddings of rural members of an unusual Protestant denomination of Anabaptist origins in Matabeleland, colonial Zimbabwe. The focus is on gendered aspects of African Christian adaptation of mission teaching amongst Ndebele members of the Brethren in Christ Church. The church in North America was firm at home on the matter of dancing (it was forbidden), and internally conflicted regarding men's garb. In the decades preceding World War II, African members of the church embraced fashionable dress for grooms and dancing at wedding feasts as common practice at BICC weddings. However, in a gendered pattern reflecting Ndebele, colonial and mission ideas of women's subjection, African women's bridal wear adhered to church teaching on Plainness, while African men's did not.
Inside the Camera Obscura: Kepler's Experiment and Theory of Optical Imagery
Authors: Dupré Sven 
Published: April 2008

AbstractIn his Paralipomena (1604) Johannes Kepler reported an experimentum that he had seen in the Dresden Kunstkammer. In one of the rooms there, which had been turned in its entirety into a camera obscura, he had witnessed the images formed by a lens. I discuss the role of this experiment in the development and foundation of his new theory of optical imagery, which made a distinction between two concepts of image, pictura and imago. My focus is on how Kepler used his report of the experiment inside the camera obscura to criticize the account of image formation given in Giovanbattista Della Porta's Magia naturalis (1589). I argue that this experiment allowed Kepler to sort out the confusion between images 'in the air'—referring to the geometrical locus of images in the perspectivist tradition of optics—and the experimentally produced 'projected images', which were empirically familiar but conceptually alien to perspectivist optics.
Guanine exchange factor RalGDS mediates exocytosis of Weibel-Palade bodies from endothelial cells
Authors: Rondaij Mariska G. , Bierings Ruben , van Agtmaal Ellen L. , Gijzen Karina A. , Sellink Erica , Kragt Astrid , Ferguson Stephen S. G. , Mertens Koen , Hannah Matthew J. , van Mourik Jan A. , Fernandez-Borja Mar , Voorberg Jan 
Published: April 2008

Abstract
The small GTP-binding protein Ral has been implicated in regulated exocytosis via its interaction with the mammalian exocyst complex. We have previously demonstrated that Ral is involved in exocytosis of Weibel-Palade bodies (WPBs). Little is known about intracellular signaling pathways that promote activation of Ral in response to ligand binding of G protein–coupled receptors. Here we show that RNAi-mediated knockdown of RalGDS, an exchange factor for Ral, results in inhibition of thrombin- and epinephrine-induced exocytosis of WPBs, while overexpression of RalGDS promotes exocytosis of WPBs. A RalGDS variant lacking its exchange domain behaves in a dominant negative manner by blocking release of WPBs. We also provide evidence that RalGDS binds calmodulin (CaM) via an amino-terminal CaM-binding domain. RalGDS association to CaM is required for Ral activation because a cell-permeable peptide comprising this RalGDS CaM-binding domain inhibits Ral activation and WPB exocytosis. Together our findings suggest that RalGDS plays a vital role in the regulation of Ral-dependent WPB exocytosis after stimulation with Ca2+- or cAMP-raising agonists.
Human mast cell activation with virus-associated stimuli leads to the selective chemotaxis of natural killer cells by a CXCL8-dependent mechanism
Authors: Burke Sarah M. , Issekutz Thomas B. , Mohan Karkada , Lee Patrick W. K. , Shmulevitz Maya , Marshall Jean S. 
Published: April 2008

AbstractHuman mast cells are found in skin and mucosal surfaces and next to blood vessels. They play a sentinel cell role in immunity, recognizing invading pathogens and producing proinflammatory mediators. Mast cells can recruit granulocytes, and monocytes in allergic disease and bacterial infection, but their ability to recruit antiviral effector cells such as natural killer (NK) cells and T cells has not been fully elucidated. To investigate the role of human mast cells in response to virus-associated stimuli, human cord blood–derived mast cells (CBMCs) were stimulated with polyinosinic·polycytidylic acid, a double-stranded RNA analog, or infected with the double-stranded RNA virus, reovirus serotype 3 Dearing for 24 hours. CBMCs responded to stimulation with polyinosinic·polycytidylic acid by producing a distinct chemokine profile, including CCL4, CXCL8, and CXCL10. CBMCs produced significant amounts of CXCL8 in response to low levels of reovirus infection, while both skin- and lung-derived fibroblasts were unresponsive unless higher doses of reovirus were used. Supernatants from CBMCs infected with reovirus induced substantial NK cell chemotaxis that was highly dependent on CXCL8 and CXCR1. These results suggest a novel role for mast cells in the recruitment of human NK cells to sites of early viral infection via CXCL8.
A new mechanism for the aging of hematopoietic stem cells: aging changes the clonal composition of the stem cell compartment but not individual stem cells
Authors: Cho Rebecca H. , Sieburg Hans B. , Muller-Sieburg Christa E. 
Published: April 2008

AbstractWhether hematopoietic stem cells (HSCs) change with aging has been controversial. Previously, we showed that the HSC compartment in young mice consists of distinct subsets, each with predetermined self-renewal and differentiation behavior. Three classes of HSCs can be distinguished based on their differentiation programs: lymphoid biased, balanced, and myeloid biased. We now show that aging causes a marked shift in the representation of these HSC subsets. A clonal analysis of repopulating HSCs demonstrates that lymphoid-biased HSCs are lost and long-lived myeloid-biased HSCs accumulate in the aged. Myeloid-biased HSCs from young and aged sources behave similarly in all aspects tested. This indicates that aging does not change individual HSCs. Rather, aging changes the clonal composition of the HSC compartment. We show further that genetic factors contribute to the age-related changes of the HSC subsets. In comparison with B6 mice, aged D2 mice show a more pronounced shift toward myeloid-biased HSCs with a corresponding reduction in the number of both T- and B-cell precursors. This suggests that low levels of lymphocytes in the blood can be a marker for HSC aging. The loss of lymphoid-biased HSCs may contribute to the impaired immune response to infectious diseases and cancers in the aged.