bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of an Automation Algorithm for TDR Bridge Scour Monitoring System
Authors: Yu Xinbao , Yu Xiong (Bill)
Published: February 2011

Bridge scour is the number one cause of bridge failures. There are high risks associated with scour-induced damages due to their catastrophic nature. Developing real time bridge scour monitoring systems is a pressing task for the research community. Such systems need to be accurate, rugged, and field worthy. Implementing automatic signal interpretation is important to ensure the success of a long term scour monitoring instrument. This paper is part of the efforts to develop a TDR system to monitor the development of scour and sedimentation process. The focus of this paper is on an automation algorithm for TDR signal analyses. It discusses the theoretical foundation of this TDR algorithm for scour depth estimation. The influence of different types of sediments and the conditions of river (including the salinity and the effects of high air entrainment and suspended sediments) on the accuracy are assessed. The study indicates that the scour monitoring algorithm based on extending a physics-based general design equation is accurate under these different conditions. This will help implement a robust algorithm to automate the TDR bridge scour monitoring system.
An Optical Fiber Bragg Grating Sensing System for Scour Monitoring
Authors: Zhou Zhi , Huang Minghua , Huang Liqing , Ou Jinping , Chen Genda
Published: February 2011

This paper proposes an optical fiber Bragg grating (FBG) sensing system for scour monitoring around the foundations of bridge piers and abutments. The new system introduces a uniform-strength fiber-reinforced polymer (FRP) beam that is instrumented with two FBG sensors in two sides of its neutral axis. The tensile and compressive strains of the beam are measured under a hydrodynamic pressure as water flowing around bridge foundations. By assuming equal temperatures around the uniform-strength beam, the difference in wavelength variations of the two embedded FBG sensors was found to be proportional to the square of flow velocity, which is directly related to scour. A prototype scour sensing system was designed and fabricated to test its sensing property in the laboratory. The experimental results indicate that the proposed system is sensitive to flow change and further monitor the scour process effectively, without responding to its surrounding hydrostatic and soil pressures.
Full-Scale Experimental Validation of High-Fidelity Wireless Measurement on a Historic Truss Bridge
Authors: Jang Shinae , Spencer Billie F. , Rice Jennifer A. , Wang Zhihao
Published: February 2011

To meet the growing demands to monitor our aging infrastructure, wireless smart sensor networks (WSSN) have been the subject of intense interest due to their versatility and low cost. However, the performance of commercially available sensors is not sufficient to realize the high-fidelity data required for SHM. In particular, synchronization among the wireless sensor nodes has been found to be inadequate for data intensive applications such as SHM. To this end, the Illinois Structural Health Monitoring Project (ISHMP) Services Toolsuite has been developed as an open-source framework to enable reliable SHM application. One of the services, RemoteSensing, was specifically designed to enable monitoring of civil infrastructure through accurate time synchronization and reliable communication. In this paper, the performance of the Imote2 wireless sensor platform using a commercially available low cost sensor board is validated directly against a wired sensor system, in the context of validation of its capability for high-fidelity data measurement for bridge health monitoring. A series of vibration tests have been conducted using human jumping to excite the subject of this study, a 76-m historic steel truss bridge in Mahomet, Illinois. The dynamic properties of the bridge have been obtained by the peak picking method for both wireless and wired systems and compare well; thus, demonstrating the efficacy of the wireless sensor system.
Test Results and Model for the Residual Compressive Strength of Concrete After a Fire
Authors: Li Yi-Hai , Franssen Jean-Marc
Published: February 2011

An investigation into temperature induced degradation of the compressive strength of concrete including that under cooling phase is carried out. The paper gathers and reviews a considerable amount of test data, considering the influence of different test parameters such as initial compressive strength, aggregate type, cooling regime and specimen shape. It is found that the compressive strength of concrete at high temperature is in accordance with the model proposed in the Eurocodes for calcareous concrete. However, during cooling phase, an additional reduction of compressive strength in concrete is observed, which can be as high as 20% of the initial strength for elevated temperatures around 500°C. Finally, a generic concrete model for temperature dependent compressive strength, accounting for both growth and cooling phase of temperature is proposed. The model can be used for simulating fire response of concrete structures subjected to natural fires or for the evaluation of residual load capacity of concrete structures after fire.
Provision of Primary Care to Patients with Chronic Cough in the Community Pharmacy Setting
Authors: Schneider Carl R , Everett Alan W , Geelhoed Elizabeth , Kendall Peter A , Murray Kevin , Garnett Peter , Salama Mariam , Clifford Rhonda M
Published: February 2011

Background:

Community pharmacies are at the forefront of primary care providers and have an important role in the referral of patients to a medical practitioner for review when necessary. Chronic cough is a common disorder in the community and requires medical assessment. The proficiency of community pharmacy staff to refer patients with chronic cough is currently unknown.

Objective:

To assess the ability of community pharmacy staff to recognize and medically refer patients with a chronic nonproductive cough.

Methods:

Following ethics approval, a simulated patient study of 156 community pharmacies in Perth, Western Australia, was conducted over a 3-month period. Simulated patients presented to the pharmacy requesting treatment for a cough. The simulated patient required a referral based on a designated scenario. Demographic details, assessment questions, and advice provided were recorded by the simulated patient immediately postvisit. A logistic regression analysis was performed, with referral for medical assessment as the dependent variable.

Results:

Of the 155 community pharmacies included in the analysis, 38% provided appropriate medical referral. Cough suppressants were provided as therapy in 72% of all visits. Predictors of medical referral were assessment of symptom duration, medical history, current medications being taken, frequency of reliever use, and the position of the pharmacy staff member conducting the consultation. A third of community pharmacies provided appropriate primary care by recommending medical referral advice to patients with chronic cough. The majority of pharmacy staff members acquired information from the patient that suggested a need for medical referral, yet did not provide referral advice.

Conclusions:

Appropriate medical referral is more likely when adequate assessment is undertaken and when a pharmacist is directly involved in the consultation. This highlights the need for pharmacies to ensure that processes are in place for patients to access the pharmacist.
Medical Utilization and Costs Associated with Statin Adherence in Medicaid Enrollees with Type 2 Diabetes
Authors: Wu Jun , Seiber Eric , Lacombe Veronique A , Nahata Milap C , Balkrishnan Rajesh
Published: February 2011

Background:

Statin adherence is a serious problem in patients with hyperlipidemia. However, it is not clear whether statin adherence is associated with medical utilization or health-care costs.

Objective:

To study statin adherence and assess associated medical utilization and health-care costs in patients with type 2 diabetes, based on a national Medicaid database.

Methods:

A retrospective claims-based study was conducted using the records of patients with type 2 diabetes with comorbid hyperlipidemia who were continuously enrolled in Medicaid from January 2004 to December 2006. All data were drawn from MarketScan Medicaid Database, including inpatient, outpatient, and drug claims. The eligible patients starting statins in 2005 were followed for 1 year to measure medication use, hospitalization, outpatient visits, emergency department (ED) visits, and health-care costs based on Medicaid medical and drug claims. Adherence was measured by medication possession ratio (MPR). Multiple regression analyses were implemented to assess statin adherence–associated outcomes, including medical utilization (risks for hospitalization and ED visits), all-cause costs, and hyperlipidemia-related medical costs.

Results:

A total of 1705 eligible patients with type 2 diabetes and hyperlipidemia were identified. The average adherence rate to statins (MPR) at 1 year was 0.61, and 37% of the patients (n = 624) were adherent to statins (MPR ≥0.8). Regression analyses indicated that diabetic patients who were adherent to statins showed lower risks for hospitalization (OR 0.80; 95% CI 0.636 to 0.966) and ED visits (OR 0.71; 95% CI 0.519 to 0.812) and decreased all-cause medical costs by 15% (p < 0.05) and hyperlipidemia-related medical costs by 12% (p < 0.05).

Conclusions:

Our study found high prevalence of nonadherence to statins in Medicaid patients with type 2 diabetes. Adherence to statins (MPR ≥0,8) was associated with reduced medical utilization and lower medical costs.
Education Funding in Massachusetts: The Effects of Aid Modifications on Vertical and Horizontal Equity
Authors: Fahy Colleen
Published: February 2011

Public school funding in Massachusetts is based on foundation budget principles. However, funding formula modifications often create disparities between district foundation budgets and actual required spending levels. This study provides an in-depth look at Massachusetts' state aid formulas used between 2004 and 2009 and utilizes two approaches to measure the effects of aid modifications on vertical and horizontal equity. The first is a regression-based approach which compares the intended effects of student characteristics on foundation spending to the actual effects on required spending. The second approach measures equity directly for each school district and uses the Tobit estimation technique to examine the effects of student and district characteristics on the equity measure. Results indicate that district characteristics such as community wealth and regional school systems increase the likelihood of a district benefiting from aid modifications. Holding community characteristics constant, there is also evidence that districts with high proportions of low income elementary school students and/or English language learners benefit from overlay provisions as well.
The Hidden Cost of School Security
Authors: DeAngelis Karen J. , Brent Brian O. , Ianni Danielle
Published: February 2011

A spate of school shootings in the U.S. has prompted policymakers to address the public's growing perception that our schools are unsafe. As education policymakers continue to press for additional security initiatives, it is important to understand the costs borne by school systems for these programs. Thus far, the scholarly literature is silent on this issue and the professional literature and mass media offer only anecdotal accounts. Using financial data from Texas and the National Center for Education Statistics' (NCES) School Survey on Crime and Safety, this study reveals how much districts spend on security, how they use those resources, and the extent to which spending differs across districts, thereby providing a comprehensive and more refined account of school security costs than is presently available.
Spectral History: The Ghost Stories of Dorothy Macardle
Authors: Malone Irina Ruppo
Published: February 2011

The article focuses on Earth-Bound: Nine Stories of Ireland (1924), a collection of ghost stories composed by Dorothy Macardle, a prolific Irish author, historian, and political journalist. The article demonstrates how Tzvetan Todorov’s concept of the reader’s hesitation, as central to the fantastic (and by extension the gothic genre), helps one understand Macardle’s engagement with the sacrificial ideology of Irish nationalism. Macardle’s collection of stories of supernatural apparitions during the troubled 1920s makes Irish history the sphere of the fantastic. It makes the reader hesitate—not between the different approaches to the supernatural—but between the conflicting ideological positions presented in the text.
The Politics of the Cliché: Flannery O’Connor’s “Revelation” and “The Displaced Person”
Authors: Harris Carole K.
Published: February 2011

Flannery O’Connor did not see herself as a political writer, and many critics perpetuate her self-image in their assessment of her work. She was, however, a keen observer of the politics of everyday conversation. By exploring the ritualized exchange of clichés between employer and hired help, particularly in “Revelation” (1964) and “The Displaced Person” (1954), this essay examines the ways in which O’Connor draws attention to the peculiar collective power of the cliché. The two stories demonstrate the politics of the cliché in her fiction, a phenomenon some critics overlook because they assume, as many of O’Connor’s characters do, that clichés are empty platitudes. “Revelation” dramatizes the politics of the cliché in a democratic setting, whereas “The Displaced Person” calls attention to the way in which clichés confirm and contest hierarchies of power in the master-servant relationship. In “Revelation,” the seemingly benign (and often hilarious) exchange of clichés between two key female characters serves to exclude a third party. The ritualization of their exchange, however, and the assumption that clichés are banal, mask this act of exclusion. “The Displaced Person” also stars two female characters who exchange clichés to exclude an outsider, and because clichés have the ability to echo unexpectedly across conversations, they function both inside and outside the women’s relationship. A variety of other speakers draw on a communal stock and recycle the same clichés. The regularities with which clichés and silences circulate in the conversations between the two key characters can thus be extrapolated to a network of other relationships within the story. Over time, a single act of exclusion on the part of two characters develops the potential to trigger escalating acts of aggression, verbal and physical. “The Displaced Person” suggests that clichés carry unexpected and potentially ever graver consequences in a collective context. “Revelation” and “The Displaced Person” enable O’Connor to explore issues of democracy in a new way; read in the context of each other, they highlight the political and ethical significance of clichés, in particular their relation to violence.
Alternate History: The Case of Nava Semel’s IsraIsland and Michael Chabon’s The Yiddish Policemen’s Union
Authors: Rovner Adam
Published: February 2011

The article sketches the development of the genre of alternate history, also called allohistory and argues that allohistory may be treated as a philosophical genre that meditates on contingency and determinism. It examines two contemporary allohistorical novels, Israeli author Nava Semel’s IsraIsland (2005) and American writer Michael Chabon’s The Yiddish Policemen’s Union (2007), that comment on the role of Israel in the Jewish imagination. The thematic and formal elements of these texts reveal how a version of allohistory can also function as a kind of detective fiction that may influence the reception of historiographic narratives.
A. R. Ammons’s Levity
Authors: Kearful Frank J.
Published: February 2011

You can locate A. R. Ammons in a line of great walkers from Wordsworth to Frank O’Hara, but what makes him different from all the rest is that despite being so peripatetic, he could not keep his feet on the ground. In poem after poem he, or a stand-in protagonist, not only turns, spins, and whirls, but rises, ascends, levitates. Thereafter comes in due course a descent, sometimes an arduous or scarifying one, but which typically finds him the better off after his return to terra firma. Levity in the transferred sense – Ammons was a whimsical, voluble, unbuttoned humorist – proves useful in contending with the perilous consequences of his levitations. In addition to his drollery, Ammons sporadically employs a prophetic voice, meditates on philosophical issues, and delves expertly into phenomena privy to the natural scientist. The composite result is a style of levity entirely his own. The extent to which he may, as a consequence of his levity, or in spite of it, be enrolled in a transcendentalist tradition of the visionary sublime stretching back to Emerson, as Harold Bloom would have it, is debatable. Five poems examined very closely give a slant on the issues involved, “Moment,” “Transcendence,” “He Held Radical Light,” “Levitation,” and “Hymn.” Other Ammons poems are discussed briefly, and incidental comparisons are made to poems by Walt Whitman, Wallace Stevens, Theodore Roethke, Elizabeth Bishop, Robert Lowell, Sylvia Plath, and John Ashbery.
Some Versions of Syllepsis
Authors: Puckett Kent
Published: February 2011

The essay takes up Garrett Stewart’s recent discussion ( Partial Answers 8.1) of the ethical tempo of a rhetorical figure, syllepsis, in order to think through some temporal consequences of the ethical turn.
Jack London’s Dialectical Philosophy between Nietzsche’s Radical Nihilism and Jules de Gaultier’s Bovarysme
Authors: Petersen Per Serritslev
Published: February 2011

I first discussed the significance of Jules de Gaultier’s philosophy in Jack London’s work in my article “Jack London’s Medusa of Truth,” published by Philosophy and Literature in 2002 (26.1). This article offers a more systematic approach to the kind of dialectical philosophy that Gaultier and London shared, and which accounts for London’s eureka response when Benjamin De Casseres first introduced him to the French philosopher’s conception of reality ( le réel ) as “a fact of opposition between two states of one and the same force,” in a form of conflict between powers of impulsion/flux and arrest. Throughout his writing career, London had been articulating and negotiating the same kind of dialectical conflict, notably the tension between his radical nihilism, the “white logic” of naturalism, and his existential need for some vitalistic impulsion, a “Maya-Lie,” what Gaultier would term bovarysme and define as “the power given man to see himself other than what he is” (“le pouvoir départi à l’homme de se concevoir autre qu’il n’est”). Saddled with Nietzsche’s intellectual conscience, London would have to cope dialectically with the inherent contradictions and partial answers of his existential position, in terms of which any synthesis of transcendence must necessarily be precarious and intermittent.
Ethics of the Event: The Apocalyptic Turn in Modernism
Authors: Borg Ruben
Published: February 2011

In their contributions to the forum on “The Ethics of Temporality” ( Partial Answers 8.1, 2009) Elana Gomel and Daphna Erdinast-Vulcan suggest that there can be no genuine ethical position without the rejection of deterministic models of thought. Such a rejection, they claim, is predicated upon a correct understanding of time as a real force for difference and heterogeneity — a force that remains irreducible to any totalizing discourse or meta-historical perspective. Taking its cue from that discussion, “Ethics of the Event” explores the paradoxes (ethical as well as epistemological) engendered by the modernist insight that time is real. In particular, the essay analyzes the strain that such an insight places upon the modern ideal of subjective self-determination. It then draws upon the work of Samuel Beckett to flesh out a literary model that is able to find some species of ethical freedom outside the framework of a fully self-determined subjectivity.
Studland Beach and Jacob’s Room : Vanessa Bell’s and Virginia Woolf’s Experiments in Portrait Making 1910–1922
Authors: Kostkowska Justyna
Published: February 2011

This essay examines Virginia Woolf’s Jacob’s Room in terms of post-impressionist influences of Roger Fry and Vanessa Bell. It demonstrates compositional similarities between Bell’s painting Studland Beach and Woolf’s novel. Both works use formal design to elicit elegiac emotion in the audience. Jacob’s Room is Woolf’s first novel that exemplifies her attention to design as a vehicle for emotion, the idea to which she had been exposed by Vanessa Bell’s and other Post-Impressionist paintings since 1910.
Maternal Serum Visfatin at 11–13 Weeks of Gestation in Gestational Diabetes Mellitus
Authors: Ferreira Ana Fatima A , Rezende Juliana C , Vaikousi Eirini , Akolekar Ranjit , Nicolaides Kypros H
Published: February 2011

BACKGROUND

Visfatin and adiponectin are produced by adipose tissue and have opposite effects on insulin resistance. Circulating concentrations of these biomarkers are altered in type 2 diabetes mellitus. We sought to examine the potential value of maternal serum visfatin and adiponectin concentrations in early pregnancy as potential biomarkers in the prediction of gestational diabetes mellitus (GDM).

METHODS

This work was a case-control study of 100 women who developed GDM and 300 nondiabetic controls. Maternal serum visfatin and adiponectin were measured between 11 and 13 weeks of gestation. Regression analysis in the nondiabetic group was performed to examine the maternal characteristics affecting the serum concentrations of visfatin and adiponectin. Likelihood ratios for GDM were calculated for visfatin and adiponectin, and performance of screening was assessed by using ROC curve analysis.

RESULTS

In the GDM group compared with the nondiabetic group, the median maternal serum visfatin concentration was increased (1.34 multiples of the median [MoM], interquartile range [IQR] 0.70–2.87, vs 1.00 MoM, IQR: 0.53–1.92; P = 0.004) and serum adiponectin was decreased (0.66 MoM, IQR 0.50–0.92, vs 1.01, IQR 0.70–1.29; P < 0.0001). In screening for GDM by a combination of maternal factors and serum adiponectin and visfatin, the estimated detection rate was 68.0% (95% CI 58.3–76.3%), at a false-positive rate of 10%.

CONCLUSIONS

At 11–13 weeks in pregnancies that develop GDM, the serum concentration of adiponectin is decreased and visfatin is increased, and these biomarkers can be combined with maternal factors to provide effective early screening for GDM.
Olivocochlear Efferent Control in Sound Localization and Experience-Dependent Learning
Authors: Irving Samuel , Moore David R. , Liberman M. Charles , Sumner Christian J.
Published: February 2011

Efferent auditory pathways have been implicated in sound localization and its plasticity. We examined the role of the olivocochlear system (OC) in horizontal sound localization by the ferret and in localization learning following unilateral earplugging. Under anesthesia, adult ferrets underwent olivocochlear bundle section at the floor of the fourth ventricle, either at the midline or laterally (left). Lesioned and control animals were trained to localize 1 s and 40 ms amplitude-roved broadband noise stimuli from one of 12 loudspeakers. Neither type of lesion affected normal localization accuracy. All ferrets then received a left earplug and were tested and trained over 10 d. The plug profoundly disrupted localization. Ferrets in the control and lateral lesion groups improved significantly during subsequent training on the 1 s stimulus. No improvement (learning) occurred in the midline lesion group. Markedly poorer performance and failure to learn was observed with the 40 ms stimulus in all groups. Plug removal resulted in a rapid resumption of normal localization in all animals. Insertion of a subsequent plug in the right ear produced similar results to left earplugging. Learning in the lateral lesion group was independent of the side of the lesion relative to the earplug. Lesions in all reported cases were verified histologically. The results suggest the OC system is not needed for accurate localization, but that it is involved in relearning localization during unilateral conductive hearing loss.
Longitudinal Near-Infrared Imaging of Myelination
Authors: Wang Changning , Wu Chunying , Popescu Daniela C. , Zhu Junqing , Macklin Wendy B. , Miller Robert H. , Wang Yanming
Published: February 2011

Myelination is one of the fundamental biological processes in the development of vertebrate nervous system. Disturbance of myelination is found to be associated with progression in many neurological diseases such as multiple sclerosis. Tremendous efforts have been made to develop novel therapeutic agents that prevent demyelination and/or promote remyelination. These efforts need to be accompanied by the development of imaging tools that permit direct quantification of myelinationin vivo. In this work, we describe a novel near-infrared fluorescence imaging technique that is capable of direct quantification of myelinationin vivo. This technique is developed based on a near-infrared fluorescent probe, 3,3′-diethylthiatricarbocyanine iodide (DBT) that readily enters the brain and specifically binds to myelinated fibers.In vivoimaging studies were first conducted in two animal models of hypermyelination and hypomyelination followed by longitudinal studies in the cuprizone-induced demyelination/remyelination mouse model. Quantitative analysis suggests that DBT is a sensitive and specific imaging probe of myelination, which complements other current myelin-imaging modalities and is of low cost.
Dissociating the Effect of Noise on Sensory Processing and Overall Decision Difficulty
Authors: Bankó Éva M. , Gál Viktor , Körtvélyes Judit , Kovács Gyula , Vidnyánszky Zoltán
Published: February 2011

It has been proposed that perceptual decision making involves a task-difficulty component, which detects perceptual uncertainty and guides allocation of attentional resources. It is thought to take place immediately after the early extraction of sensory information and is specifically reflected in a positive component of the event related potentials, peaking at ∼220 ms after stimulus onset. However, in the previous research, neural processes associated with the monitoring of overall task difficulty were confounded by those associated with the increased sensory processing demands as a result of adding noise to the stimuli. Here we dissociated the effect of phase noise on sensory processing and overall decision difficulty using a face gender categorization task. Task difficulty was manipulated either by adding noise to the stimuli or by adjusting the female/male characteristics of the face images. We found that it is the presence of noise and not the increased overall task difficulty that affects the electrophysiological responses in the first 300 ms following stimulus onset in humans. Furthermore, we also showed that processing of phase-randomized as compared to intact faces is associated with increased fMRI responses in the lateral occipital cortex. These results revealed that noise-induced modulation of the early electrophysiological responses reflects increased visual cortical processing demands and thus failed to provide support for a task-difficulty component taking place between the early sensory processing and the later sensory accumulation stages of perceptual decision making.
Functional Nicotinic Acetylcholine Receptors Containing α6 Subunits Are on GABAergic Neuronal Boutons Adherent to Ventral Tegmental Area Dopamine Neurons
Authors: Yang Kechun , Buhlman Lori , Khan Ghous M. , Nichols Robert A. , Jin Guozhang , McIntosh J. Michael , Whiteaker Paul , Lukas Ronald J. , Wu Jie
Published: February 2011

Diverse nicotinic acetylcholine receptor (nAChR) subtypes containing different subunit combinations can be placed on nerve terminals or soma/dendrites in the ventral tegmental area (VTA). nAChR α6 subunit message is abundant in the VTA, but α6*–nAChR cellular localization, function, pharmacology, and roles in cholinergic modulation of dopaminergic (DA) neurons within the VTA are not well understood. Here, we report evidence for α6β2*–nAChR expression on GABA neuronal boutons terminating on VTA DA neurons. α-Conotoxin (α-Ctx) MII labeling coupled with immunocytochemical staining localizes putative α6*–nAChRs to presynaptic GABAergic boutons on acutely dissociated, rat VTA DA neurons. Functionally, acetylcholine (ACh) induces increases in the frequency of bicuculline-, picrotoxin-, and 4-aminopyridine-sensitive miniature IPSCs (mIPSCs) mediated by GABAAreceptors. These increases are abolished by α6*–nAChR-selective α-Ctx MII or α-Ctx PIA (1 nm) but not by α7 (10 nmmethyllycaconitine) or α4* (1 μmdihydro-β-erythroidine)–nAChR-selective antagonists. ACh also fails to increase mIPSC frequency in VTA DA neurons prepared from nAChR β2 knock-out mice. Moreover, ACh induces an α-Ctx PIA-sensitive elevation in intraterminal Ca2+in synaptosomes prepared from the rat VTA. Subchronic exposure to 500 nmnicotine reduces ACh-induced GABA release onto the VTA DA neurons, as does 10 d of systemic nicotine exposure. Collectively, these results indicate that α6β2*–nAChRs are located on presynaptic GABAergic boutons within the VTA and modulate GABA release onto DA neurons. These presynaptic α6β2*–nAChRs likely play important roles in nicotinic modulation of DA neuronal activity.
Recurrent Processing in V1/V2 Contributes to Categorization of Natural Scenes
Authors: Koivisto Mika , Railo Henry , Revonsuo Antti , Vanni Simo , Salminen-Vaparanta Niina
Published: February 2011

Humans are able to categorize complex natural scenes very rapidly and effortlessly, which has led to an assumption that such ultra-rapid categorization is driven by feedforward activation of ventral brain areas. However, recent accounts of visual perception stress the role of recurrent interactions that start rapidly after the activation of V1. To study whether or not recurrent processes play a causal role in categorization, we applied fMRI-guided transcranial magnetic stimulation on early visual cortex (V1/V2) and lateral occipital cortex (LO) while the participants categorized natural images as containing animals or not. The results showed that V1/V2 contributed to categorization speed and to subjective perception during a long activity period before and after the contribution of LO had started. This pattern of results suggests that recurrent interactions in visual cortex between areas along the ventral stream and striate cortex play a causal role in categorization and perception of natural scenes.
Wnt5aIs a Transcriptional Target ofDlxHomeogenes and Promotes Differentiation of Interneuron ProgenitorsIn VitroandIn Vivo
Authors: Paina Sara , Garzotto Donatella , DeMarchis Silvia , Marino Marco , Moiana Alessia , Conti Luciano , Cattaneo Elena , Perera Marzia , Corte Giorgio , Calautti Enzo , Merlo Giorgio R.
Published: February 2011

During brain development, neurogenesis, migration, and differentiation of neural progenitor cells are regulated by an interplay between intrinsic genetic programs and extrinsic cues. TheDlxhomeogene transcription factors have been proposed to directly control the genesis and maturation of GABAergic interneurons of the olfactory bulb (OB), subpallium, and cortex. Here we provide evidence thatDlxgenes promote differentiation of olfactory interneurons via the signaling moleculeWnt5a. Dlx2 and Dlx5 interact with homeodomain binding sequences within theWnt5alocus and activate its transcription. Exogenously providedWnt5apromotes GABAergic differentiation in dissociated OB neurons and in organ-type brain cultures. Finally, we show that the Dlx-mutant environment is unfavorable for GABA differentiation,in vivoandin vitro. We conclude thatDlxgenes favor interneuron differentiation also in a non-cell-autonomous fashion, via expression ofWnt5a.
Neural Correlates of Instrumental Contingency Learning: Differential Effects of Action–Reward Conjunction and Disjunction
Authors: Liljeholm Mimi , Tricomi Elizabeth , O'Doherty John P. , Balleine Bernard W.
Published: February 2011

Contingency theories of goal-directed action propose that experienced disjunctions between an action and its specific consequences, as well as conjunctions between these events, contribute to encoding the action–outcome association. Although considerable behavioral research in rats and humans has provided evidence for this proposal, relatively little is known about the neural processes that contribute to the two components of the contingency calculation. Specifically, while recent findings suggest that the influence of action–outcome conjunctions on goal-directed learning is mediated by a circuit involving ventromedial prefrontal, medial orbitofrontal cortex, and dorsomedial striatum, the neural processes that mediate the influence of experienced disjunctions between these events are unknown. Here we show differential responses to probabilities of conjunctive and disjunctive reward deliveries in the ventromedial prefrontal cortex, the dorsomedial striatum, and the inferior frontal gyrus. Importantly, activity in the inferior parietal lobule and the left middle frontal gyrus varied with a formal integration of the two reward probabilities, ΔP, as did response rates and explicit judgments of the causal efficacy of the action.
Sleep Contributes to the Strengthening of Some Memories Over Others, Depending on Hippocampal Activity at Learning
Authors: Rauchs Géraldine , Feyers Dorothée , Landeau Brigitte , Bastin Christine , Luxen André , Maquet Pierre , Collette Fabienne
Published: February 2011

Memory consolidation benefits from sleep. In addition to strengthening some memory traces, another crucial, albeit overlooked, function of memory is to erase irrelevant information. Directed forgetting is an experimental approach consisting in presenting “to be remembered” and “to be forgotten” information that allows selectively decreasing or increasing the strength of individual memory traces according to the instruction provided at learning. This paradigm was used in combination with functional MRI to determine, in humans, what specifically triggers at encoding sleep-dependent compared with time-dependent consolidation. Our data indicate that relevant items that subjects strived to memorize are consolidated during sleep to a greater extent than items that participants did not intend to learn. This process appears to depend on a differential activation of the hippocampus at encoding, which acts as a signal for the offline reprocessing of relevant memories during postlearning sleep episodes.
Frizzled3 Is Required for Neurogenesis and Target Innervation during Sympathetic Nervous System Development
Authors: Armstrong Alissa , Ryu Yun Kyoung , Chieco Deanna , Kuruvilla Rejji
Published: February 2011

The sympathetic nervous system has served as an amenable model system to investigate molecular mechanisms underlying developmental processes in the nervous system. While much attention has been focused on neurotrophic factors controlling survival and connectivity of postmitotic sympathetic neurons, relatively little is known about signaling mechanisms regulating development of sympathetic neuroblasts. Here, we report that Frizzled3 (Fz3), a member of the Wnt receptor family, is essential for maintenance of dividing sympathetic neuroblasts. InFz3−/−mice, sympathetic neuroblasts exhibit decreased proliferation and premature cell cycle exit.Fz3−/−sympathetic neuroblasts also undergo enhanced apoptosis, which could not be rescued by eliminating the proapoptotic factor,Bax. These deficits result in reduced generation of sympathetic neurons and pronounced decreases in the size of sympathetic chain ganglia. Furthermore, the axons of sympathetic neurons that persist inFz3−/−ganglia are able to extend out of sympathetic ganglia toward distal targets, but fail to fully innervate final peripheral targets. The cell cycle exit, but not target innervation, defects inFz3−/−mice are phenocopied in mice with conditional ablation of β-catenin, a component of canonical Wnt signaling, in sympathetic precursors. Sympathetic ganglia and innervation of target tissues appeared normal in mice lacking a core planar cell polarity (PCP) component, Vangl2. Together, our results suggest distinct roles for Fz3 during sympathetic neuron development; Fz3 acts at early developmental stages to maintain a pool of dividing sympathetic precursors, likely via activation of β-catenin, and Fz3 functions at later stages to promote innervation of final peripheral targets by postmitotic sympathetic neurons.
Short- and Long-Lasting Consequences ofIn VivoNicotine Treatment on Hippocampal Excitability
Authors: Penton Rachel E. , Quick Michael W. , Lester Robin A. J.
Published: February 2011

The potential for relapse following cessation of drug use can last for years, implying the induction of stable changes in neural circuitry. In hippocampal slices from rats treated with nicotine for 1 week, withdrawal from nicotinein vivoproduces an increase in CA1 pyramidal cell excitability that persists up to 9 months. Immediately upon drug cessation, the enhanced excitability depends on input from regions upstream of CA1, while the long-term excitability change (> 4 weeks) is expressed as an increase in the intrinsic excitability of CA1 neurons. Re-exposure to nicotinein vitrorestores hippocampal function to control levels via activation of high-affinity nicotinic acetylcholine receptors after 1 d of withdrawal, but not at times >4 weeks. Thus, nicotinein vivofirst induces homeostatic adaptations followed by other more robust neural changes. These mechanisms may contribute to hippocampal localized cue-motivated reinstatement of drug-seeking and/or cognitive deficits observed during withdrawal.
Taxol Facilitates Axon Regeneration in the Mature CNS
Authors: Sengottuvel Vetrivel , Leibinger Marco , Pfreimer Mariana , Andreadaki Anastasia , Fischer Dietmar
Published: February 2011

Mature retinal ganglion cells (RGCs) cannot normally regenerate axons into the injured optic nerve but can do so after lens injury. Astrocyte-derived ciliary neurotrophic factor and leukemia inhibitory factor have been identified as essential key factors mediating this effect. However, the outcome of this regeneration is still limited by inhibitors associated with the CNS myelin and the glial scar. The current study demonstrates that Taxol markedly enhanced neurite extension of mature RGCs and PC12 cells by stabilization of microtubules and desensitized axons toward myelin and chondroitin sulfate proteoglycan (CSPG) inhibitionin vitrowithout reducing RhoA activation.In vivo, the local application of Taxol at the injury site of the optic nerve of rats enabled axons to regenerate beyond the lesion site but did not affect the intrinsic regenerative state of RGCs. Furthermore, Taxol treatment markedly increased lens injury-mediated axon regenerationin vivo, delayed glial scar formation, suppressed CSPG expression, and transiently reduced the infiltration of macrophages at the injury site. Thus, microtubule-stabilizing compounds such as Taxol might be promising candidates as adjuvant drugs in the treatment of CNS injuries particularly when combined with interventions stimulating the intrinsic regenerative state of neurons.
It's About Time: How Input Timing Is Used and Not Used To Create Emergent Properties in the Auditory System
Authors: Gittelman Joshua X , Pollak George D.
Published: February 2011

The hypothesis for directional selectivity of frequency modulations (FMs) invokes a mechanism with an honored tradition in sensory neurobiology, the relative timing of excitation and inhibition. The proposal is that the timing disparity is created by asymmetrical locations of excitatory tuning and inhibitory sidebands. Thus, cells in which the inhibitory sidebands are tuned to frequencies lower than the excitatory tuning are selective for downward sweeping FMs, because frequencies first generate excitation followed by inhibition. Upward sweeping FMs, in contrast, first evoke inhibition that either leads or is coincident with the excitation and prevents discharges. Here we evaluated FM directional selectivity within vivowhole-cell recordings from the inferior colliculus of awake bats. From the whole-cell recordings, we derived synaptic conductance waveforms evoked by downward and upward FMs. We then tested the effects of shifting inhibition relative to excitation in a model and found that latency shifts had only minor effects on EPSP amplitudes that were often <1.0 mV/ms shift. However, when the PSPs peaked close to spike threshold, even small changes in latency could cause some cells to fire more strongly to a particular FM direction and thus change its directional selectivity. Furthermore, the effect of shifting inhibition depended strongly on initial latency differences and the shapes of the conductance waveforms. We conclude that “timing” is more than latency differences between excitation and inhibition, and response selectivity depends on a complex interaction between the timing, the shapes, and magnitudes of the excitatory and inhibitory conductances and spike threshold.
Large-Scale Calcium Waves Traveling through Astrocytic NetworksIn Vivo
Authors: Kuga Nahoko , Sasaki Takuya , Takahara Yuji , Matsuki Norio , Ikegaya Yuji
Published: February 2011

Macroscopic changes in cerebral blood flow, such as those captured by functional imaging of the brain, require highly organized, large-scale dynamics of astrocytes, glial cells that interact with both neuronal and cerebrovascular networks. However, astrocyte activity has been studied mainly at the level of individual cells, and information regarding their collective behavior is lacking. In this work, we monitored calcium activity simultaneously from hundreds of mouse hippocampal astrocytesin vivoand found that almost all astrocytes participated en masse in regenerative waves that propagated from cell to cell (referred to here as “glissandi”). Glissandi emerged depending on the neuronal activity and accompanied a reduction in infraslow fluctuations of local field potentials and a decrease in the flow of red blood cells. This novel phenomenon was heretofore overlooked, probably because of the high vulnerability of astrocytes to light damage; glissandi occurred only when observed at much lower laser intensities than previously used.
Dopaminergic Projections from Midbrain to Primary Motor Cortex Mediate Motor Skill Learning
Authors: Hosp Jonas A. , Pekanovic Ana , Rioult-Pedotti Mengia S. , Luft Andreas R.
Published: February 2011

The primary motor cortex (M1) of the rat contains dopaminergic terminals. The origin of this dopaminergic projection and its functional role for movement are obscure. Other areas of cortex receive dopaminergic projections from the ventral tegmental area (VTA) of the midbrain, and these projections are involved in learning phenomena. We therefore hypothesized that M1 receives a dopaminergic projection from VTA and that this projection mediates the learning of a motor skill by inducing cellular plasticity events in M1. Retrograde tracing from M1 of Long–Evans rats in conjunction with tyrosine hydroxylase immunohistochemistry identified dopaminergic cell bodies in VTA. Electrical stimulation of VTA induced expression of the immediate-early gene c-fosin M1, which was blocked by intracortical injections of D1and D2antagonists. Destroying VTA dopaminergic neurons prevented the improvements in forelimb reaching seen in controls during daily training. Learning recovered on administration of levodopa into the M1 of VTA-lesioned animals. Lesioning VTA did not affect performance of an already learned skill, hence, left movement execution intact. These findings provide evidence that dopaminergic terminals in M1 originate in VTA, contribute to M1 plasticity, and are necessary for successful motor skill learning. Because VTA dopaminergic neurons are known to signal rewards, the VTA-to-M1 projection is a candidate for relaying reward information that could directly support the encoding of a motor skill within M1.
Ventral Striatum and Orbitofrontal Cortex Are Both Required for Model-Based, But Not Model-Free, Reinforcement Learning
Authors: McDannald Michael A. , Lucantonio Federica , Burke Kathryn A. , Niv Yael , Schoenbaum Geoffrey
Published: February 2011

In many cases, learning is thought to be driven by differences between the value of rewards we expect and rewards we actually receive. Yet learning can also occur when the identity of the reward we receive is not as expected, even if its value remains unchanged. Learning from changes in reward identity implies access to an internal model of the environment, from which information about the identity of the expected reward can be derived. As a result, such learning is not easily accounted for by model-free reinforcement learning theories such as temporal difference reinforcement learning (TDRL), which predicate learning on changes in reward value, but not identity. Here, we used unblocking procedures to assess learning driven by value- versus identity-based prediction errors. Rats were trained to associate distinct visual cues with different food quantities and identities. These cues were subsequently presented in compound with novel auditory cues and the reward quantity or identity was selectively changed. Unblocking was assessed by presenting the auditory cues alone in a probe test. Consistent with neural implementations of TDRL models, we found that the ventral striatum was necessary for learning in response to changes in reward value. However, this area, along with orbitofrontal cortex, was also required for learning driven by changes in reward identity. This observation requires that existing models of TDRL in the ventral striatum be modified to include information about the specific features of expected outcomes derived from model-based representations, and that the role of orbitofrontal cortex in these models be clearly delineated.
Cross-Sensory Modulation of Primary Sensory Cortex Is Developmentally Regulated by Early Sensory Experience
Authors: Ghoshal Ayan , Tomarken Andrew , Ebner Ford
Published: February 2011

The presence of cross-sensory influences on neuronal responses in primary sensory cortex has been observed previously using several different methods. To test this idea in rat S1 barrel cortex, we hypothesized that auditory stimuli combined with whisker stimulation (“cross-sensory” stimuli) may modify response levels to whisker stimulation. Since the brain has been shown to have a remarkable capacity to be modified by early postnatal sensory activity, manipulating postnatal sensory experiences would be predicted to alter the degree of cross-sensory interactions. To test these ideas, we raised rats with or without whisker deprivation and with or without postnatal exposure to repeated auditory clicks. We recorded extracellular responses under urethane anesthesia from barrel cortex neurons in response to principal whisker stimulation alone, to auditory click stimulation alone, or to a cross-sensory stimulus. The responses were compared statistically across different stimulus conditions and across different rearing groups. Barrel neurons did not generate action potentials in response to auditory click stimuli alone in any rearing group. However, in cross-sensory stimulus conditions the response magnitude was facilitated in the 0–15 ms post-whisker-stimulus epoch in all rearing conditions, whereas modulation of response magnitude in a later 15–30 ms post-whisker-stimulus epoch was significantly different in each rearing condition. The most significant cross-sensory effect occurred in rats that were simultaneously whisker deprived and click reared. We conclude that there is a modulatory type of cross-sensory auditory influence on normal S1 barrel cortex, which can be enhanced by early postnatal experiences.