bluuebunny/crossref_metadata_2025 huggingface dataset:
Gastric duodenal metaplasia in duodenal adenomas
Authors: Rubio C A
Published: July 2006

Backgound:In cases of known aetiology, gastric duodenal metaplasia (GMD) is a reversible lesion. In cases of unknown aetiology, the fate of GMD remains elusive. GMD was recently found in a duodenal adenoma.

Aim:To audit the frequency of GMD occurring in a cohort of duodenal adenomas.

Methods:Filed H&E-stained sections from 306 consecutive duodenal adenomas were investigated for the presence of GMD.

Results:68% of the adenomas (n = 208) were from patients with familial adenomatous polyposis (FAP), and the remaining 32% (n = 98) were sporadic. GMD was found in 31.7% (66/208) of the duodenal FAP adenomas and in 59.2% (58/98) of the duodenal sporadic adenomas (p<0.05). The causes for this difference are elusive.

Conclusions:As for other metaplasias of the gastrointestinal tract (intestinal metaplasia of the oesophagus and of the stomach, and metaplastic–hyperplastic polyposis of the colon, known to antedate neoplastic transformation), a subset of GMDs of unknown cause might be present in the duodenal mucosa before adenomatous changes ensue. That subset of GMD might have neoplastic proclivity similar to the metaplastic epithelium in other organs of the gastrointestinal tract. The known carcinogenic effect of high concentrations of bile acids and pancreatic juices bathing the duodenal mucosa carrying an irreversible subset of GDM might set aflame the adenomatous neoplastic transformation in these patients.
Cytology of chordoid meningioma: a series of five cases with emphasis on differential diagnoses
Authors: Lui Philip C W , Chau Tony K F , Wong Steve S , Lau Patrick P L , Tse Gary M K , Thomas Teresa M M , Ng Ho Keung
Published: July 2006

Background:Chordoid meningioma is a rare meningioma variant characterised by epithelioid cord-like tumour cells in a myxoid stroma. It is classified as grade II (World Health Organization) tumours, as they have a tendency to behave more aggressively than traditional meningiomas and have a greater likelihood of recurrence.

Aims:To report the features of intraoperative imprint smears of five cases of chordoid meningioma.

Methods:The intraoperative squash smears were reviewed for cellularity, cellular atypia, mitotic figure, cytoplasmic vacuolation, intranuclear inclusion, presence of a cohesive cord of tumour cells, whorl-like structure, psammoma bodies, chronic inflammatory cells (lymphocytes and plasma cells), background mucin and necrosis.

Results:All cases were of moderate to high cellularity, with cohesive cords of bland tumour cells possessing uniformly round nuclei with smooth nuclear outline, stippled chromatin and small nucleoli, with cytoplasmic vacuolation and chronic inflammatory cells in the background. Intranuclear inclusions (80%) and whorl-like structures (60%) were also common. Necrotic background, psammoma bodies or mitotic figures were consistently absent.

Conclusions:The cytological features of chordoid mengiomas are distinctive, and intraoperative imprint diagnosis is feasible.
LOOKING FOR NEW PARADIGMS TOWARDS A BIOLOGICAL-MATHEMATICAL THEORY OF COMPLEX MULTICELLULAR SYSTEMS
Authors: BELLOMO NICOLA , FORNI GUIDO
Published: July 2006

This paper deals with the development of new paradigms based on the methods of the mathematical kinetic theory for active particles to model the dynamics of large systems of interacting cells. Interactions are ruled, not only by laws of classical mechanics, but also by a few biological functions which are able to modify the above laws. The paper technically shows, also by reasoning on specific examples, how the theory can be applied to model large complex systems in biology. The last part of the paper deals with a critical analysis and with the indication of research perspectives concerning the challenging target of developing a biological-mathematical theory for the living matter.
ISOGEOMETRIC ANALYSIS: APPROXIMATION, STABILITY AND ERROR ESTIMATES FOR h-REFINED MESHES
Authors: BAZILEVS Y. , BEIRÃO DA VEIGA L. , COTTRELL J. A. , HUGHES T. J. R. , SANGALLI G.
Published: July 2006

We begin the mathematical study of Isogeometric Analysis based on NURBS (non-uniform rational B-splines). Isogeometric Analysis is a generalization of classical Finite Element Analysis (FEA) which possesses improved properties. For example, NURBS are capable of more precise geometric representation of complex objects and, in particular, can exactly represent many commonly engineered shapes, such as cylinders, spheres and tori. Isogeometric Analysis also simplifies mesh refinement because the geometry is fixed at the coarsest level of refinement and is unchanged throughout the refinement process. This eliminates geometrical errors and the necessity of linking the refinement procedure to a CAD representation of the geometry, as in classical FEA. In this work we study approximation and stability properties in the context of h-refinement. We develop approximation estimates based on a new Bramble–Hilbert lemma in so-called "bent" Sobolev spaces appropriate for NURBS approximations and establish inverse estimates similar to those for finite elements. We apply the theoretical results to several cases of interest including elasticity, isotropic incompressible elasticity and Stokes flow, and advection-diffusion, and perform numerical tests which corroborate the mathematical results. We also perform numerical calculations that involve hypotheses outside our theory and these suggest that there are many other interesting mathematical properties of Isogeometric Analysis yet to be proved.
ASYMPTOTIC ENTANGLEMENT OF TWO INDEPENDENT SYSTEMS IN A COMMON BATH
Authors: BENATTI F. , FLOREANINI R.
Published: July 2006

Two non-interacting systems immersed in a common bath and evolving with a Markovian, completely positive dynamics can become initially entangled via a purely noisy mechanism. Remarkably, for certain phenomenologically relevant environments, the quantum correlations can persist even in the asymptotic long-time regime.
DENSE CODING WITH MULTIPARTITE QUANTUM STATES
Authors: BRUß DAGMAR , LEWENSTEIN MACIEJ , SEN(DE) ADITI , SEN UJJWAL , D'ARIANO GIACOMO MAURO , MACCHIAVELLO CHIARA
Published: July 2006

We consider generalizations of the dense coding protocol with an arbitrary number of senders and either one or two receivers, sharing a multiparty quantum state, and using a noiseless channel. For the case of a single receiver, the capacity of such information transfer is found exactly. It is shown that the capacity is not enhanced by allowing the senders to perform joint operations. We provide a nontrivial upper bound on the capacity in the case of two receivers. We also give a classification of the set of all multiparty states in terms of their usefulness for dense coding. We provide examples for each of these classes, and discuss some of their properties.
INFORMATION TRANSMISSION VIA ENTANGLED QUANTUM STATES IN GAUSSIAN CHANNELS WITH MEMORY
Authors: CERF NICOLAS J. , CLAVAREAU JULIEN , ROLAND JÉRÉMIE , MACCHIAVELLO CHIARA
Published: July 2006

Gaussian quantum channels have recently attracted a growing interest, since they may lead to a tractable approach to the generally hard problem of evaluating quantum channel capacities. However, the analysis performed so far has always been restricted to memoryless channels. Here, we consider the case of a bosonic Gaussian channel with memory, and show that the classical capacity can be significantly enhanced by employing entangled input symbols instead of product symbols.
EFFECTS OF NOISE ON SPIN NETWORK CLONING
Authors: DE CHIARA GABRIELE , FAZIO ROSARIO , MONTANGERO SIMONE , MACCHIAVELLO CHIARA , PALMA G. MASSIMO
Published: July 2006

We analyze the effects of noise on quantum cloning based on the spin network approach. A noisy environment interacting with the spin network is modeled both in a classical scenario, with a classical fluctuating field, and in a fully quantum scenario, in which the spins are coupled with a bath of harmonic oscillators. We compare the realization of cloning with spin networks and with traditional quantum gates in the presence of noise, and show that spin network cloning is more robust.
ENTANGLEMENT ENTROPY AND QUANTUM FIELD THEORY: A NON-TECHNICAL INTRODUCTION
Authors: CALABRESE PASQUALE , CARDY JOHN
Published: July 2006

We give a pedagogical and non-technical introduction to the quantum field theory approach to entanglement entropy. Particular attention is devoted to the one space dimensional case, with a linear dispersion relation, that, at a quantum critical point, can be effectively described by a two-dimensional conformal field theory.
EXPERIMENTAL REALIZATIONS OF THE 1 → M UNIVERSAL CLONING MACHINE
Authors: MASULLO L. , RICCI M. , SCIARRINO F. , SECONDI V. , DE MARTINI F.
Published: July 2006

We report the first experimental realizations of the 1 → M universal cloning machine. Two approaches are carefully described: the adoption of a state symmetrization linear optical procedure and of the quantum injected optical parametric amplifier. Furthermore, this device is adopted to generate optimally distinguishable multi-photon quantum superposition states.
MASSIVE QUANTUM MEMORIES BY PERIODICALLY INVERTED DYNAMIC EVOLUTIONS
Authors: GIAMPAOLO S. M. , ILLUMINATI F. , DI LISI A. , MAZZARELLA G.
Published: July 2006

We introduce a general scheme to realize perfect quantum state reconstruction and storage in systems of interacting qubits. This novel approach is based on the idea of controlling the residual interactions by suitable external controls that, acting on the inter-qubit couplings, yield time-periodic inversions in the dynamical evolution, thus cancelling exactly the effects of quantum state diffusion. We illustrate the method for spin systems on closed rings with XY residual interactions, showing that it enables the massive storage of arbitrarily large numbers of local states, and we demonstrate its robustness against several realistic sources of noise and imperfections.
ENTANGLEMENT MONOTONES AND MAXIMALLY ENTANGLED STATES IN MULTIPARTITE QUBIT SYSTEMS
Authors: OSTERLOH ANDREAS , SIEWERT JENS
Published: July 2006

We present a method to construct entanglement measures for pure states of multipartite qubit systems. The key element of our approach is an antilinear operator that we call comb in reference to the hairy-ball theorem. For qubits (i.e. spin 1/2) the combs are automatically invariant under SL (2, ℂ). This implies that the filters obtained from the combs are entanglement monotones by construction. We give alternative formulae for the concurrence and the 3-tangle as expectation values of certain antilinear operators. As an application we discuss inequivalent types of genuine four-, five- and six-qubit entanglement.
ENTANGLEMENT DISTRIBUTION WITH GLOBAL CONTROL IN A STAR-SHAPED MULTI-SPLITTER
Authors: PATERNOSTRO M. , McANENEY H. , KIM M. S.
Published: July 2006

Distributed quantum information processing (QIP) is a promising way to bypass problems due to unwanted interactions between elements. However, this strategy presupposes the engineering of protocols for remote processors. In many of them, pairwise entanglement is a key resource. We study a model which distributes entanglement among elements of a delocalized network without local control. The model is efficient both in finite- and infinite-dimensional Hilbert spaces. We suggest a setup of electromechanical systems to implement our proposal.
DISCRETE TIME QUANTUM WALK ON A LINE WITH TWO PARTICLES
Authors: SHERIDAN L. , PAUNKOVIĆ N. , OMAR Y. , BOSE S.
Published: July 2006

We introduce the idea of a quantum walk with two particles and study it for the case of a discrete time walk on a line. We consider both separable and maximally entangled initial conditions, and show how the entanglement and the relative phase between the states describing the coin degree of freedom of each particle will influence the evolution of the quantum walk. In particular, these factors will have consequences for the distance between the particles and the probability of finding them at a given point, yielding results that cannot be obtained from a separable initial state, be it pure or mixed. Finally, we review briefly proposals for implementations.
CREATION OF STABLE MULTIPARTITE ENTANGLED STATES IN SPIN CHAINS WITH DEFECTS
Authors: SANTOS LEA F.
Published: July 2006

We show how defects in a spin chain described by the XXZ model may be used to generate entangled states, such as Bell and W states, and how to maintain them with high fidelity. We also discuss, in the presence of several excitations, how the anisotropy of the system may be combined with defects to effectively assist in the creation of the desired states.
TEAM GOAL COMMITMENT IN INNOVATIVE PROJECTS
Authors: HOEGL MARTIN , PARBOTEEAH K. PRAVEEN
Published: July 2006

In this paper, we investigate a relatively neglected but important aspect of team research, namely team goal commitment or the team member's attachment to the team goal. Specifically, we examine whether the performance effect of team goal commitment is contingent on the level of innovativeness of the team task. Furthermore, we also examine five controllable team-level antecedent factors to team goal commitment. Results provide support for the hypothesis that team goal commitment is related to performance only in teams with highly innovative tasks. Moreover, we find three factors (i.e., constructive task feedback, participative decision-making and small team size) related to team goal commitment. Surprisingly, outcome interdependence and team-external obligations are not related to team goal commitment. Implications for practice and research are discussed.
THE EFFECTIVENESS OF IDEA CAPTURE SCHEMES
Authors: LEACH DESMOND J. , STRIDE CHRISTOPHER B. , WOOD STEPHEN J.
Published: July 2006

Innovation at work is mainly driven by employees' ideas. This paper reports a study of the effectiveness (e.g., rate of suggestion making) of schemes for capturing these ideas. Based on a survey of 182 UK organizations, the study shows that decentralized suggestion schemes and work-based systems are more effective than centralized and informal schemes. The extent of planning, publicity, feedback and management support given to the scheme, and the type of reward offered to employees, also independently account for variation in effectiveness. Publicity and non-monetary rewards, though, are found to be most decisive, regardless of scheme type. Learning culture also affects the rate of suggestion making, though the effect is greater for centralized and decentralized schemes than for the others. The key implication of the findings is that by paying particular attention to how they are advertised and how participation is rewarded, organizations could improve the return on their idea capture schemes.
EGF and HB-EGF modulate inward potassium current in human bladder urothelial cells from normal and interstitial cystitis patients
Authors: Sun Yan , Chen Mingkui , Lowentritt Benjamin H. , Van Zijl P. Sean , Koch Kristopher R. , Keay Susan , Simard J. Marc , Chai Toby C.
Published: July 2006

Interstitial cystitis (IC) is an idiopathic condition characterized by bladder hyperalgesia. Studies have shown cytokine and purinergic signaling abnormalities in cultured bladder urothelial cells (BUC) from IC patients. We performed single-cell electrophysiological studies in both normal and IC BUC. A strongly inward rectifying potassium current with conductance of the Kir2.1 channel was identified in normal BUC. This current was significantly reduced in IC BUC. Kir2.1 protein and mRNA were detected in both IC and normal BUC. Epidermal growth factor (EGF) caused a dose-dependent decrease in the inward potassium current in normal BUC. EGF is secreted in higher amounts by IC BUC and is known to decrease Kir2.1 conductance by phosphorylation of Kir2.1. Genistein, a nonspecific phosphorylation inhibitor, increased the inward potassium current in IC BUC and blocked the effect of EGF on normal BUC. Treatment of IC BUC with heparin-binding epidermal growth factor-like growth factor (HB-EGF), previously shown to be secreted in lower amounts by IC BUC, significantly increased inward potassium current. These data show that the inward potassium current in BUC can be modulated by EGF and HB-EGF. Changes in BUC membrane potassium conductance caused by altered levels of EGF and HB-EGF may therefore play a role in the pathophysiology of IC.
Niacin-bound chromium enhances myocardial protection from ischemia-reperfusion injury
Authors: Thirunavukkarasu Mahesh , Penumathsa Suresh Varma , Juhasz Bela , Zhan Lijun , Cordis Gerald , Altaf Elham , Bagchi Manashi , Bagchi Debasis , Maulik Nilanjana
Published: July 2006

A novel niacin-bound, chromium-based energy formula (EF; InterHealth Nutraceuticals, Benicia, CA) has been developed in conjunction with d-ribose, caffeine, ashwagandha extract (containing 5% withanolides), and selected amino acids. We have assessed the efficacy of oral administration of EF (40 mg·kg body wt−1·day−1) in male and female rats over a period of 90 consecutive days on the cardiovascular and pathophysiological functions in an isolated rat heart model. After 30, 60, and 90 days of treatment with EF, the hearts of male and female rats were subjected to 30 min of global ischemia followed by 2 h of reperfusion and were measured for myocardial ATP, creatine phosphate (CP), phosphorylated AMP kinase (p-AMPK), and heat shock proteins. Myocardial ATP and CP levels were increased in both male and female rats after EF treatment compared with the controls. Western blot analyses were performed to quantify the expression of stress-related proteins such as heat shock proteins (HSP-70, -32, and -25) and are found to be increased in both male and female rats after EF treatment. The p-AMPK level, which is a sensor for the energy state in various cell types, was also found to be increased after treatment with EF in both male and female rats. Aortic flow, maximum first derivative of developed pressure, left ventricular developed pressure, and infarct size were observed after ischemia-reperfusion and found to be significantly improved in EF-treated rats compared with control animals. Thus EF demonstrated long-term safety as well as exhibiting significant cardioprotective ability during ischemia and reperfusion injury by increased energy production, improved cardiac function, and reduced infarct size.
Modulation of BK channel calcium affinity by differential phosphorylation in developing ovine basilar artery myocytes
Authors: Lin Mike T. , Hessinger David A. , Pearce William J. , Longo Lawrence D.
Published: July 2006

Large-conductance Ca2+-sensitive K+ (BK) channel activity is greater in basilar artery smooth muscle cells (SMCs) of the fetus than the adult, and this increased activity is associated with a lower BK channel Ca2+ set point (Ca0). Associated PKG activity is three times greater in BK channels from fetal than adult myocytes, whereas associated PKA activity is three times greater in channels from adult than fetal myocytes. We hypothesized that the change in Ca0 during development results from different levels of channel phosphorylation. In inside-out membrane patch preparations of basilar artery SMCs from adult and fetal sheep, we measured BK channel activity in four states of phosphorylation: native, dephosphorylated, PKA phosphorylated, and PKG phosphorylated. BK channels from adult and fetus exhibited similar voltage-activation curves, Ca0 values, and Ca2+ dissociation constants ( Kd) for the dephosphorylated, PKA phosphorylated, and PKG phosphorylated states. However, voltage-activation curves of native fetal BK channels shifted significantly to the left of those of the adult, with Ca0 and Kd values half those of the adult. For the two age groups at each of the phosphorylation states, Ca0 and Kd produced linear relations when plotted against voltage at half-maximal channel activation. We conclude that the Ca0 and Kd values of the BK channel can be modulated by differential channel phosphorylation. Lower Ca0 and Kd values in BK channels of fetal myocytes can be explained by a greater extent of channel phosphorylation of fetal than adult myocytes.
Ventral Hippocampal Neurons Project Axons Simultaneously to the Medial Prefrontal Cortex and Amygdala in the Rat
Authors: Ishikawa Akinori , Nakamura Shoji
Published: July 2006

The ventral hippocampus (VH) may have an important role in spatial memory processes and emotional behaviors through connections with the medial prefrontal cortex (mPFC) and amygdala. Although the mPFC and amygdala receive afferent projections from the VH, it has not been determined whether the individual VH neurons project to both the mPFC and the amygdala. In this study, antidromic responses to the mPFC and amygdala stimulation were evoked in single VH neurons. In addition, VH neurons were retrogradely double-labeled with fluorescent tracers injected in the mPFC and amygdala. VH neurons projecting to both the mPFC and amygdala were predominantly located in the subiculum and CA1 and bifurcated near or at the soma. Our anatomical and electrophysiological evidence for the presence of VH neurons projecting to both the mPFC and amygdala provides a previously unrecognized pathway from the hippocampus that simultaneously activates the mPFC and amygdala.
Synaptic Democracy in Active Dendrites
Authors: Rumsey Clifton C. , Abbott L. F.
Published: July 2006

Given the extensive attenuation that can occur along dendritic cables, location within the dendritic tree might appear to be a dominant factor in determining the impact of a synapse on the postsynaptic response. By this reasoning, distal synapses should have a smaller effect than proximal ones. However, experimental evidence from several types of neurons, such as CA1 pyramidal cells, indicates that a compensatory strengthening of synapses counteracts the effect of location on synaptic efficacy. A form of spike-timing-dependent plasticity (STDP), called anti-STDP, combined with non-Hebbian activity-dependent plasticity can account for the equalization of synaptic efficacies. This result, obtained originally in models with unbranched passive cables, also arises in multi-compartment models with branched and active dendrites that feature backpropagating action potentials, including models with CA1 pyramidal morphologies. Additionally, when dendrites support the local generation of action potentials, anti-STDP prevents runaway dendritic spiking and locally balances the numbers of dendritic and backpropagating action potentials. Thus in multiple ways, anti-STDP eliminates the location dependence of synapses and allows Hebbian plasticity to operate in a more “democratic” manner.
Air Movement Evokes Electro-Olfactogram Oscillations in the Olfactory Epithelium and Modulates Olfactory Processing in a Slug
Authors: Ito Iori , Watanabe Satoshi , Kirino Yutaka
Published: July 2006

In many animals, neurons in the olfactory system have been shown to respond not only to odorants but also to air movements. However, the manner in which the mechanical dynamics of odor stimulation affect olfactory processing remains poorly understood. Using a series of flow rates and odor concentrations from clean air to high-concentration vapors, we systematically analyzed the effects of air movement and odor concentration on olfactory processing. We extracellularly recorded local field potentials and spike units from the olfactory epithelium (OE) and tentacular nerve (TN), which connects the first and second relay centers of olfactory information, in the terrestrial slug Limax marginatus. We found that clean air puffs at a flow rate of 0.18 ml/s (gentle wind), but not high-concentration odor puffs at lower flow rates, induced electro-olfactogram (EOG) oscillations in the OE with a constant frequency (2.5 Hz), regardless of the odor. Surgically isolated OE preparations also showed these EOG oscillations, indicating that the oscillations arose from the OE independently of the downstream circuits. The EOG oscillations entrained the slower spontaneous TN oscillations (1–2 Hz) to the fixed rhythm (2.5 Hz). Spontaneous and odor-evoked units were phase-locked to the TN oscillation peaks. This TN oscillation entrainment by the EOG oscillations caused stronger phase-locking, specifically TN oscillation peaks and EOG oscillation troughs. Taken together, these results suggest that when odors are carried by a gentle wind, the air movement induces EOG oscillations and modulates rhythmic spike patterning of olfactory outputs to the second olfactory relay center in Limax.
Postural Muscle Tone in the Body Axis of Healthy Humans
Authors: Gurfinkel Victor , Cacciatore Timothy W. , Cordo Paul , Horak Fay , Nutt John , Skoss Rachel
Published: July 2006

Across the entire human body, postural tone might play its most critical role in the body's axis because the axis joins the four limbs and head into a single functioning unit during complex motor tasks as well as in static postures. Although postural tone is commonly viewed as low-level, tonic motor activity, we hypothesized that postural tone is both tonically and dynamically regulated in the human axis even during quiet stance. Our results describe the vertical distribution of postural muscle tone in the neck, trunk, and hips of standing human adults. Each subject stood blindfolded on a platform that axially rotated the neck, trunk, or pelvis at 1°/s and ±10° relative to the neutral position (i.e., facing forward). The measured resistance to axial rotation was highest in the trunk and lowest in the neck and was characterized by several nonlinear features including short-range stiffness and hysteresis. In half of the subjects, axial muscle activity was relatively constant during axial rotation, and in the other half, muscle activity was modulated by lengthening and shortening reactions, i.e., decreasing activity in lengthening muscles and increasing activity in shortening muscles, respectively. Axial resistance to rotation was reduced in subjects whose muscle activity was modulated. The results indicate that axial tone is modulated sensitively and dynamically, this control originates, at least in part, from tonic lengthening and shortening reactions, and a similar type of control appears to exist for postural tone in the proximal muscles of the arm.
Effects of Electrically Coupled Inhibitory Networks on Local Neuronal Responses to Intracortical Microstimulation
Authors: Butovas Sergejus , Hormuzdi Sheriar G. , Monyer Hannah , Schwarz Cornelius
Published: July 2006

Using in vivo multielectrode electrophysiology in mice, we investigated the underpinnings of a local, long-lasting firing rate suppression evoked by intracortical microstimulation. Synaptic inhibition contributes to this suppression as it was reduced by pharmacological blockade of γ-aminobutyric acid type B (GABAB) receptors. Blockade of GABAB receptors also abolished the known sublinear addition of inhibitory response duration after repetitive electrical stimulation. Furthermore, evoked inhibition was weaker and longer in connexin 36 knockout (KO) mice that feature decoupled cortical inhibitory networks. In supragranular layers of KO mice even an unusually long excitatory response (≤50 ms) appeared that was never observed in wild-type (WT) mice. Furthermore, the spread and duration of very fast oscillations (>200 Hz) evoked by microstimulation at a short latency were strongly enhanced in KO mice. In the spatial domain, lack of connexin 36 unmasked a strong anisotropy of inhibitory spread. Although its reach along layers was almost the same as that in WT mice, the spread across cortical depth was severely hampered. In summary, the present data suggest that connexin 36–coupled networks significantly shape the electrically evoked cortical inhibitory response. Electrical coupling renders evoked cortical inhibition more precise and strong and ensures a uniform spread along the two cardinal axes of neocortical geometry.
Spinobulbar Neurons in Lamprey: Cellular Properties and Synaptic Interactions
Authors: Einum James F. , Buchanan James T.
Published: July 2006

An in vitro preparation of the nervous system of the lamprey, a lower vertebrate, was used to characterize the properties of spinal neurons with axons projecting to the brain stem [i.e., spinobulbar (SB) neurons)]. To identify SB neurons, extracellular electrodes on each side of the spinal cord near the obex recorded the axonal spikes of neurons impaled with sharp intracellular microelectrodes in the rostral spinal cord. The ascending spinal neurons ( n = 144) included those with ipsilateral (iSB) (63/144), contralateral (cSB) (77/144), or bilateral (bSB) (4/144) axonal projections to the brain stem. Intracellular injection of biocytin revealed that the SB neurons had small- to medium-size somata and most had dendrites confined to the ipsilateral side of the cord, although about half of the cSB neurons also had contralateral dendrites. Most SB neurons had multiple axonal branches including descending axons. Electrophysiologically, the SB neurons were similar to other lamprey spinal neurons, firing spikes throughout long depolarizing pulses with some spike-frequency adaptation. Paired intracellular recordings between SB and reticulospinal (RS) neurons revealed that SB neurons made either excitatory or inhibitory synapses on RS neurons and the SB neurons received excitatory input from RS neurons. Mutual excitation and feedback inhibition between pairs of RS and SB neurons were observed. The SB neurons also received excitatory inputs from primary mechanosensory neurons (dorsal cells), and these same SB neurons were rhythmically active during fictive swimming, indicating that SB neurons convey both sensory and locomotor network information to the brain stem.
Dissociating Verbal and Nonverbal Conceptual Processing in the Human Brain
Authors: Thierry Guillaume , Price Cathy J.
Published: July 2006

Functional neuroimaging has highlighted a left-hemisphere conceptual system shared by verbal and nonverbal processing despite neuropsychological evidence that the ability to recognize verbal and nonverbal stimuli can doubly dissociate in patients with left- and right-hemisphere lesions, respectively. Previous attempts to control for perceptual differences between verbal and nonverbal stimuli in functional neuroimaging studies may have hidden differences arising at the conceptual level. Here we used a different approach and controlled for perceptual confounds by looking for amodal verbal and nonverbal conceptual activations that are common to both the visual and auditory modalities. In addition to the left-hemisphere conceptual system activated by all meaningful stimuli, we observed the left/right double dissociation in verbal and nonverbal conceptual processing, predicted by neuropsychological studies. Left middle and superior temporal regions were selectively more involved in comprehending words—heard or read—and the right midfusiform and right posterior middle temporal cortex were selectively more involved in making sense of environmental sounds and images. Thus, the neuroanatomical basis of a verbal/nonverbal conceptual processing dissociation is established.
Orbitofrontal Cortex and Social Behavior: Integrating Self-monitoring and Emotion-Cognition Interactions
Authors: Beer Jennifer S. , John Oliver P. , Scabini Donatella , Knight Robert T.
Published: July 2006

The role of the orbitofrontal cortex in social behavior remains a puzzle. Various theories of the social functions of the orbitofrontal cortex focus on the role of this area in either emotional processing or its involvement in online monitoring of behavior (i.e., self-monitoring). The present research attempts to integrate these two theories by examining whether improving the self-monitoring of patients with orbitofrontal damage is associated with the generation of emotions needed to guide interpersonal behavior. Patients with orbitofrontal damage, patients with lateral prefrontal damage, and healthy controls took part in an interpersonal task. After completing the task, participants' self-monitoring was increased by showing them a videotape of their task performance. In comparison to healthy controls and patients with lateral prefrontal damage, orbitofrontal damage was associated with objectively inappropriate social behavior. Although patients with orbitofrontal damage were aware of social norms of intimacy, they were unaware that their task performance violated these norms. The embarrassment typically associated with inappropriate social behavior was elicited in these patients only after their self-monitoring increased from viewing their videotaped performance. These findings suggest that damage to the orbitofrontal cortex impairs self-insight that may preclude the generation of helpful emotional information. The results highlight the role of the orbitofrontal cortex in the interplay of self-monitoring and emotional processing and suggest avenues for neurorehabilitation of patients with social deficits subsequent to orbitofrontal damage.
Electrophysiological Correlates of Similarity-based Interference during Detection of Visual Forms
Authors: Conci Markus , Gramann Klaus , Müller Hermann J. , Elliott Mark A.
Published: July 2006

Illusory figure completion demonstrates the ability of the visual system to integrate information across gaps. Mechanisms that underlie figural emergence support the interpolation of contours and the filling-in of form information [Grossberg, S., & Mingolla, E. Neural dynamics of form perception: Boundary completion, illusory figures and neon colour spreading. Psychological Review, 92, 173–211, 1985]. Although both processes contribute to figure formation, visual search for an illusory target configuration has been shown to be susceptible to interfering form, but not contour, information [Conci, M., Müller, H. J., & Elliott, M. A. The contrasting impact of global and local object attributes on Kanizsa figure detection. Submitted]. Here, the physiological basis of form interference was investigated by recording event-related potentials elicited from contour- and surface-based distracter interactions with detection of a target Kanizsa figure. The results replicated the finding of form interference and revealed selection of the target and successful suppression of the irrelevant distracter to be reflected by amplitude differences in the N2pc component (240–340 msec). In conclusion, the observed component variations reflect processes of target selection on the basis of integrated form information resulting from figural completion processes.
Fear Recognition Ability Predicts Differences in Social Cognitive and Neural Functioning in Men
Authors: Corden Ben , Critchley Hugo D. , Skuse David , Dolan Raymond J.
Published: July 2006

By testing the facial fear-recognition ability of 341 men in the general population, we show that 8.8% have deficits akin to those seen with acquired amygdala damage. Using psychological tests and functional magnetic resonance imaging (fMRI) we tested the hypothesis that poor fear recognition would predict deficits in other domains of social cognition and, in response to socially relevant stimuli, abnormal activation in brain regions that putatively reflect engagement of the “social brain.” On tests of “theory of mind” ability, 25 “low fear scorers” (LFS) performed significantly worse than 25 age- and IQ-matched “normal (good) fear scorers” (NFS). In fMRI, we compared evoked activity during a gender judgement task to neutral faces portraying different head and eye gaze orientations in 12 NFS and 12 LFS subjects. Despite identical between-group accuracy in gender discrimination, LFS demonstrated significantly reduced activation in amygdala, fusiform gyrus, and anterior superior temporal cortices when viewing faces with direct versus averted gaze. In a functional connectivity analysis, NFS show enhanced connectivity between the amygdala and anterior temporal cortex in the context of direct gaze; this enhanced coupling is absent in LFS. We suggest that important individual differences in social cognitive skills are expressed within the healthy male population, which appear to have a basis in a compromised neural system that underpins social information processing.
Neural Representations of Self versus Other: Visual-Spatial Perspective Taking and Agency in a Virtual Ball-tossing Game
Authors: David Nicole , Bewernick Bettina H. , Cohen Michael X. , Newen Albert , Lux Silke , Fink Gereon R. , Shah N. Jon , Vogeley Kai
Published: July 2006

Human self-consciousness relies on the ability to distinguish between oneself and others. We sought to explore the neural correlates involved in self-other representations by investigating two critical processes: perspective taking and agency. Although recent research has shed light on the neural processes underlying these phenomena, little is known about how they overlap or interact at the neural level. In a two-factorial functional magnetic resonance imaging (fMRI) experiment, participants played a ball-tossing game with two virtual characters (“avatars”). During an active/agency (ACT) task, subjects threw a ball to one of the avatars by pressing a button. During a passive/nonagency (PAS) task, they indicated which of the other avatars threw the ball. Both tasks were performed from a first-person perspective (1PP), in which subjects interacted from their own perspective, and a third-person perspective (3PP), in which subjects interacted from the perspective of an avatar with another location in space. fMRI analyses revealed overlapping activity in medial prefrontal regions associated with representations of one's own perspective and actions (1PP and ACT), and overlapping activity in temporal-occipital, premotor, and inferior frontal, as well as posterior parietal regions associated with representation of others' perspectives and actions (3PP and PAS). These findings provide evidence for distinct neural substrates underlying representations of the self and others and provide support for the idea that the medial prefrontal cortex crucially contributes to a neural basis of the self. The lack of a statistically significant interaction suggests that perspective taking and agency represent independent constituents of self-consciousness.
The Role of the Posterior Fusiform Gyrus in Reading
Authors: Devlin Joseph T. , Jamison Helen L. , Gonnerman Laura M. , Matthews Paul M.
Published: July 2006

Studies of skilled reading [Price, C. J., & Mechelli, A. Reading and reading disturbance. Current Opinion in Neurobiology, 15, 231–238, 2005], its acquisition in children [Shaywitz, B. A., Shaywitz, S. E., Pugh, K. R., Mencl, W. E., Fulbright, R. K., Skudlarski, P., et al. Disruption of posterior brain systems for reading in children with developmental dyslexia. Biological Psychiatry, 52, 101–110, 2002; Turkeltaub, P. E., Gareau, L., Flowers, D. L., Zeffiro, T. A., & Eden, G. F. Development of neural mechanisms for reading. Nature Neuroscience, 6, 767–773, 2003], and its impairment in patients with pure alexia [Leff, A. P., Crewes, H., Plant, G. T., Scott, S. K., Kennard, C., & Wise, R. J. The functional anatomy of single word reading in patients with hemianopic and pure alexia. Brain, 124, 510–521, 2001] all highlight the importance of the left posterior fusiform cortex in visual word recognition. We used visual masked priming and functional magnetic resonance imaging to elucidate the specific functional contribution of this region to reading and found that (1) unlike words, repetition of pseudowords (“solst-solst”) did not produce a neural priming effect in this region, (2) orthographically related words such as “corner-corn” did produce a neural priming effect, but (3) this orthographic priming effect was reduced when prime-target pairs were semantically related (“teacher-teach”). These findings conflict with the notion of stored visual word forms and instead suggest that this region acts as an interface between visual form information and higher order stimulus properties such as its associated sound and meaning. More importantly, this function is not specific to reading but is also engaged when processing any meaningful visual stimulus.
Cerebral Asymmetry in the Fusiform Areas Predicted the Efficiency of Learning a New Writing System
Authors: Xue Gui , Chen Chuansheng , Jin Zhen , Dong Qi
Published: July 2006

There are great individual differences in learning abilities, but their neural bases, especially among normal populations, are not well understood. Using functional magnetic resonance imaging and a training paradigm, the present study investigated individual differences in cerebral asymmetry in fusiform regions when processing a new writing system and their correlation to subsequent visual character learning. Twelve Chinese adults underwent a 2-week training to learn 120 Korean characters and they were scanned before and after the training. Results showed that left-hemispheric dominance during the pretraining task was predictive of better posttraining performance. These results have significant implications for our understanding of the neural basis of language learning, especially in terms of individual differences.
Repetitive Transcranial Magnetic Stimulation of Broca's Area Affects Verbal Responses to Gesture Observation
Authors: Gentilucci Maurizio , Bernardis Paolo , Crisi Girolamo , Volta Riccardo Dalla
Published: July 2006

The aim of the present study was to determine whether Broca's area is involved in translating some aspects of arm gesture representations into mouth articulation gestures. In Experiment 1, we applied low-frequency repetitive transcranial magnetic stimulation over Broca's area and over the symmetrical loci of the right hemisphere of participants responding verbally to communicative spoken words, to gestures, or to the simultaneous presentation of the two signals. We performed also sham stimulation over the left stimulation loci. In Experiment 2, we performed the same stimulations as in Experiment 1 to participants responding with words congruent and incongruent with gestures. After sham stimulation voicing parameters were enhanced when responding to communicative spoken words or to gestures as compared to a control condition of word reading. This effect increased when participants responded to the simultaneous presentation of both communicative signals. In contrast, voicing was interfered when the verbal responses were incongruent with gestures. The left stimulation neither induced enhancement on voicing parameters of words congruent with gestures nor interference on words incongruent with gestures. We interpreted the enhancement of the verbal response to gesturing in terms of intention to interact directly. Consequently, we proposed that Broca's area is involved in the process of translating into speech aspects concerning the social intention coded by the gesture. Moreover, we discussed the results in terms of evolution to support the theory [Corballis, M. C. (2002). From hand to mouth: The origins of language. Princeton, NJ: Princeton University Press] proposing spoken language as evolved from an ancient communication system using arm gestures.
The Influence of Criterion Shifts on Electrophysiological Correlates of Recognition Memory
Authors: Azimian-Faridani N. , Wilding E. L.
Published: July 2006

The claim that event-related potentials (ERPs) index familiarity was assessed by acquiring ERPs during a recognition memory task in which participants were instructed to adopt different decision criteria in separate retrieval phases. In one, the instructions were to respond “old” only when confident that this was the correct response, and to respond “new” otherwise (the conservative condition). In the other, the instructions were to respond new only when confident that this was the correct response (the liberal condition). The rationale for this approach was that the level of familiarity licensing an old response would be higher in the conservative than in the liberal condition, and if ERPs index familiarity, this would be reflected in changes to the putative ERP index. This index comprises relatively more positive-going neural activity for correct judgments to old than to new items, which is evident from 300 to 500 msec poststimulus at mid-frontal scalp locations. In keeping with task instructions, participants made more old responses in the liberal than in the conservative condition. There were reliable mid-frontal ERP old/new effects in both conditions, and the ERPs evoked by correct judgments to words in the conservative condition were relatively more positive-going than those in the liberal condition. This finding is consistent with the view that the mid-frontal ERP old/new effect indexes familiarity, and in combination with other ERP findings, provides strong support for dual-process accounts of recognition memory.
Visual Working Memory Is Impaired when the Medial Temporal Lobe Is Damaged
Authors: Olson Ingrid R. , Moore Katherine Sledge , Stark Marianna , Chatterjee Anjan
Published: July 2006

The canonical description of the role of the medial temporal lobes (MTLs) in memory is that short-term forms of memory (e.g., working memory [WM]) are spared when the MTL is damaged, but longer term forms of memory are impaired. Tests used to assess this have typically had a heavy verbal component, potentially allowing explicit rehearsal strategies to maintain the WM trace over the memory delay period. Here we test the hypothesis that the MTL is necessary for visual WM when verbal rehearsal strategies are difficult to implement. In three patients with MTL damage we found impairments in spatial, face, and color WM, at delays as short as 4 sec. Impaired memory could not be attributed to memory load or perceptual problems. These findings suggest that the MTLs are critical for accurate visual WM.
When Peanuts Fall in Love: N400 Evidence for the Power of Discourse
Authors: Nieuwland Mante S. , Van Berkum Jos J. A.
Published: July 2006

In linguistic theories of how sentences encode meaning, a distinction is often made between the context-free rule-based combination of lexical-semantic features of the words within a sentence (“semantics”), and the contributions made by wider context (“pragmatics”). In psycholinguistics, this distinction has led to the view that listeners initially compute a local, context-independent meaning of a phrase or sentence before relating it to the wider context. An important aspect of such a two-step perspective on interpretation is that local semantics cannot initially be overruled by global contextual factors. In two spoken-language event-related potential experiments, we tested the viability of this claim by examining whether discourse context can overrule the impact of the core lexical-semantic feature animacy, considered to be an innate organizing principle of cognition. Two-step models of interpretation predict that verb-object animacy violations, as in “The girl comforted the clock,” will always perturb the unfolding interpretation process, regardless of wider context. When presented in isolation, such anomalies indeed elicit a clear N400 effect, a sign of interpretive problems. However, when the anomalies were embedded in a supportive context (e.g., a girl talking to a clock about his depression), this N400 effect disappeared completely. Moreover, given a suitable discourse context (e.g., a story about an amorous peanut), animacy-violating predicates (“the peanut was in love”) were actually processed more easily than canonical predicates (“the peanut was salted”). Our findings reveal that discourse context can immediately overrule local lexical-semantic violations, and therefore suggest that language comprehension does not involve an initially context-free semantic analysis.