bluuebunny/crossref_metadata_2025 huggingface dataset:
Human Phenome Based on Traditional Chinese Medicine — A Solution to Congenital Syndromology
Authors: Li-Ling Jesse
Published: February 2004

The occurrence of many congenital syndromes has long been an enigma. Clinically, the phenotype of any given genetic defect usually varies to some extent, whilst, pathogenetically, features within each syndrome are probably interconnected, albeit by largely unknown mechanisms. Through its unique theories such as the Jing-Mai (variously translated as the Channels, Vessels or Meridians), Zang-Fu (the Yin and Yang internal organs) and Wu-Xing (translated as the Five-Phase Correspondence or Five-Element theory), traditional Chinese medicine (TCM) seems to have comprehensively summarized the makeup of the human phenotypes. By combining the above TCM theories with modern medical knowledge, the intrinsic mechanisms between various aspects of the phenotypic makeup of the human individual, i.e. the Human Phenome, may be deduced. Analysis of congenital syndromes in light of the Human Phenome seems to suggest that various genetic defects may cause diseases in a similar fashion; i.e. primarily with structural abnormalities distributed along the four Jing-Mai connected with the Kidneys (midline defects) as well as "Marrow" aberrations (anomalies of hematology/immunology, endocrine, central nervous system and the bones). The derived Human Phenome may thereby enable a better understanding of such conditions and provide a model for the study of multigenic traits. On the other hand, blind spots of clinical observation and unknown aspects of human nature, e.g. circuits formed by the Jing-Mai, symmetries of the Jing-Mai and Zang-Fu, and correspondences between body physiques, spiritual factors and the external world may also be deduced. The TCM-based Human Phenome may thereby offer a fresh view for genotype-phenotype correlations, insights into gene-development mechanisms, as well as potential directions for the development of new treatments.
Genetic Distinction of Radix Adenophorae From Its Adulterants by the DNA Sequence of 5S-rRNA Spacer Domains
Authors: Zhao K. J. , Dong T. T. X. , Cui X. M. , Tu P. F. , Tsim K. W. K.
Published: February 2004

Radix Adenophorae (Shashen), a traditional Chinese medicine commonly used as an antitussive and expectorant, is derived from roots of Adenophora stricta Miq. and Adenophora tetraphylla (Thunb.) Fisch. Twelve species and varieties of Adenophora and Glehnia, however, could act as substitutes or adulterants of Radix Adenophorae on the commercial markets in South East Asia, and roots of Adenophora hunanensis Nannf. and Glihnia littoralis F. Schmidt ex Miq. are the most common examples. The authentic identification of dried roots of A. stricta and A. tetraphylla, however, is difficult on the basis of appearance and morphology. A molecular genetic approach was developed here to identify the species of Radix Adenophorae. The 5S-rRNA spacer domains (~250 bp) were amplified by the polymerase chain reaction (PCR) from genomic DNAs isolated from A. stricta, A. tetraphylla, A. hunanensis and G. littoralis, and subsequently, the nucleotide sequences were determined. Diversity in DNA sequence and restriction enzyme mapping among various species were found in their 5S-rRNA spacer domains, which could serve as markers for authentic identification of Radix Adenophorae.
Extraction and Chromatography-Mass Spectrometric Analysis of the Active Principles from Selected Chinese Herbs and Other Medicinal Plants
Authors: Wang Xiaosuo , Kapoor Vimal , Smythe George A.
Published: February 2004

Medicinal herbs have a long history of use in the practice of traditional Chinese medicine and a substantial body of evidence has, over recent decades, demonstrated a range of important pharmacological properties. Western biomedical researchers are examining not only the efficacy of the traditional herbal products but, through the use of a range of bioassays and analytical techniques, are developing improved methods to isolate and characterize active components. This review briefly describes the different extraction methodologies used in the preparation of herbal extracts and reviews the utility of chromatography-mass spectrometry for the analysis of their active components. In particular, applications of gas or liquid chromatography with mass spectrometry for the isolation and characterization of active components of ginseng are critically assessed. The analysis of toxic substances from herb extracts with mass spectrometric techniques is also discussed along with the potential for mass spectrometric methods to investigate the proteomics of herbal extracts.
GEOMETRICAL BARRIER IN A SUPERCONDUCTING STRIP: SINGLE-VORTEX APPROACH
Authors: ELISTRATOV A. A. , BOBRIKOV O. A. , MAKSIMOV I. L. , JEUDY V.
Published: February 2004

The problem of the geometrical barrier is solved for the vortex fragment entering from the corners of a superconducting strip, placed into a perpendicular magnetic field. A single-vortex Gibbs potential is constructed for the first time taking into account the actual current/field distribution in a sample of rectangular cross-section. The dependence of the vortex inclination angle as well as the vortex altitude on the external magnetic field is determined. Geometrical barrier-suppression field is found at which near-the-edge vortices start penetrating deep into the strip.
STRUCTURAL INVESTIGATION OF xFe2O3 · (100-x)[P2O5 · CaO] AND x(Fe2O3 · V2O5) · (100-x) [P2O5 · CaO] GLASS SYSTEMS BY IR SPECTROSCOPY
Authors: ARDELEAN I. , ANDRONACHE C. , CÎMPEAN C. , PǍŞCUŢǍ P.
Published: February 2004

Glasses from the two systems, x Fe 2 O 3 · (100-x)[ P 2 O 5 · CaO ] and x( Fe 2 O 3 · V 2 O 5) · (100-x)[ P 2 O 5 · CaO ] with 0 ≤ x ≤ 50 mol% were prepared under the same conditions and characterized by IR spectroscopy. The way in which Fe 2 O 3 and ( Fe 2 O 3 · V 2 O 5) influences the local structure of these glasses was analyzed.
EXCLUSION PROCESSES AND BOUNDARY CONDITIONS
Authors: ROSHANI FARINAZ , KHORRAMI MOHAMMAD
Published: February 2004

A family of boundary conditions corresponding to exclusion processes is introduced. This family is a generalization of the boundary conditions corresponding to the simple exclusion process, the drop-push model, and the one-parameter solvable family of pushing processes with certain rates on the continuum.1–3 The conditional probabilities are calculated using the Bethe ansatz, and it is shown that at large times they behave like the corresponding conditional probabilities of the family of diffusion-pushing processes introduced in Refs. 1–3.
DIDERO 3G A STRATEGIC NETWORK PLANNING TOOL FOR 3G MOBILE NETWORKS
Authors: HACKBARTH KLAUS D. , PORTILLA J. ANTONIO
Published: February 2004

Strategic Planning for mobile networks has to consider the evolution from the existing 2nd Generation GSM architecture to a long term 3rd Generation UMTS architecture over various intermediate steps in the form of hybrid networks. The study of this evolution requires a corresponding Strategic Planning tool. This article deals with Strategic Network Planning and develops the corresponding models considering aspects like radio propagation, multi-service traffic and user mobility. The article presents a corresponding strategic planning tool which allows to study the evolution of a mobile network under the corresponding input data in the form of a service and topographic scenarios. The application of the tool to a specific network region is shown and costing perspectives for the different services are discussed.
A HYBRID BAYESIAN NETWORK-BASED MULTI-AGENT SYSTEM AND A DISTRIBUTED SYSTEMS ARCHITECTURE FOR THE DRUG CRIME KNOWLEDGE MANAGEMENT
Authors: PENDHARKAR PARAG C. , BHASKAR RAHUL
Published: February 2004

In this paper, we describe an approach for building a hybrid Bayesian network-based multi-agent system for drug crime knowledge management. We use distributed artificial intelligence architecture to create a multi-agent information system that integrates distributed knowledge sources and information to aid decision-making. Our comparison of the hybrid system with a previously developed stand-alone expert system Sherpa, which was in use at a large drug crime investigation facility, shows that the current system compares similar to the existing system in terms of efficiency and effectiveness of knowledge management. We illustrate how the proposed hybrid bayesian network-based can be implemented in the distributed computing network environment.
Presynaptic modulation of evoked NE release contributes to sympathetic activation after pressure overload
Authors: Akers Wendell S. , Cassis Lisa A.
Published: February 2004

Activation of the sympathetic nervous system is well documented in heart failure. Our previous studies demonstrated an increase in evoked norepinephrine (NE) release from left ventricle (LV) slices at 10 days of pressure overload. The purpose of this study was to test the hypothesis that presynaptic modulation of NE release contributes to sympathetic activation after pressure overload. We examined the functional status of the presynaptic α2- and β2-receptors and ANG II subtype 1 (AT1) receptors in LV slices from 10-day aortic constricted (AC) and sham-operated (SO) rats. Evoked 3H overflow from LV slices preloaded with [3H]NE was increased in AC rats. The α2-agonist UK-14,304 decreased evoked 3H overflow with no differences between groups. The β2-agonist salbutamol increased evoked 3H overflow with greater sensitivity in slices from AC rats. The β-antagonist propranolol decreased evoked 3H overflow from LV slices of AC rats but not controls. ANG II increased evoked 3H overflow with greater sensitivity in slices from AC rats. These data support the hypothesis that aberrant presynaptic modulation of catecholamine release contributes to sympathetic activation after pressure overload.
Mitochondrial-derived free radicals mediate asbestos-induced alveolar epithelial cell apoptosis
Authors: Panduri Vijayalakshmi , Weitzman Sigmund A. , Chandel Navdeep S. , Kamp David W.
Published: February 2004

Asbestos causes pulmonary toxicity by mechanisms that in part involve reactive oxygen species (ROS). However, the precise source of ROS is unclear. We showed that asbestos induces alveolar epithelial cell (AEC) apoptosis by a mitochondrial-regulated death pathway. To determine whether mitochondrial-derived ROS are necessary for causing asbestos-induced AEC apoptosis, we utilized A549-ρο cells that lack mitochondrial DNA and a functional electron transport. As expected, antimycin, which induces an oxidative stress by blocking mitochondrial electron transport at complex III, increased dichlorofluoroscein (DCF) fluorescence in A549 cells but not in A549-ρο cells. Compared with A549 cells, ρο cells have less asbestos-induced ROS production, as assessed by DCF fluorescence, and reductions in total glutathione levels as well as less caspase-9 activation and apoptosis, as assessed by TdT-mediated dUTP nick end labeling staining and DNA fragmentation. A mitochondrial anion channel inhibitor that prevents ROS release from the mitochondria to the cytoplasm also blocked asbestos-induced A549 cell caspase-9 activation and apoptosis. Finally, a role for nonmitochondrial-derived ROS with exposure to high levels of asbestos (50 μg/cm2) was suggested by our findings that an iron chelator (phytic acid or deferoxamine) or a free radical scavenger (sodium benzoate) provided additional protection against asbestos-induced caspase-9 activation and DNA fragmentation in ρο cells. We conclude that asbestos fibers affect mitochondrial DNA and functional electron transport, resulting in mitochondrial-derived ROS production that in turn mediates AEC apoptosis. Nonmitochondrial-associated ROS may also contribute to AEC apoptosis, particularly with high levels of asbestos exposure.
Chronic hyperaldosteronism in a transgenic mouse model fails to induce cardiac remodeling and fibrosis under a normal-salt diet
Authors: Wang Qing , Clement Sophie , Gabbiani Giulio , Horisberger Jean-Daniel , Burnier Michel , Rossier Bernard C. , Hummler Edith
Published: February 2004

Primary aldosteronism causes severe hypertension in humans (Conn's syndrome) with cardiac hypertrophy, characterized by a fibrosis more severe than the one observed in patients with essential hypertension. This suggests that aldosterone by itself may have specific and direct effects on cardiac remodeling through the activation of the cardiac mineralocorticoid receptor. Experimental evidence obtained in studying uninephrectomized rats treated with aldosterone or deoxycorticosterone (DOC) together with salt loading has led to similar conclusions. To examine the direct consequences of chronically elevated aldosterone levels on cardiac pathophysiology, we analyzed a mouse model (α-epithelial Na channel −/−Tg) that is normotensive under normal-salt diet but exhibits chronic hyperaldosteronism. Sixteen-month-old transgenic rescue mice that were kept under a regular salt diet that contains a small amount of sodium (0.3% Na+) displayed a compensated PHA-1 phenotype with normal body weight, normal kidney index, normal blood pressure, but 6.3-fold elevated plasma aldosterone levels compared with the age-matched control group. Peripheral resistance of distal colon to aldosterone was shown by a significant decrease of the amiloride-sensitive rectal potential difference, and its diurnal cyclicity was blunted. Despite chronically high plasma aldosterone levels, these animals do not show any evidence of cardiac hypertrophy, remodeling, or fibrosis, using collagen staining and anti-α-skeletal and α-smooth actin immunochemical labeling of heart sections. Cardiac fibrosis as seen in DOC- or aldosterone/salt-treated animal models is therefore likely to be due to the synergistic effect of salt, aldosterone, and other confounding factors rather than to the elevated circulating aldosterone levels alone.
Relating maximum airway dilation and subsequent reconstriction to reactivity in human lungs
Authors: Black Lauren D. , Henderson Angela C. , Atileh Haytham , Israel Elliot , Ingenito Edward P. , Lutchen Kenneth R.
Published: February 2004

Measures of airway resistance (Raw) during deep inspiration (DI) suggest that asthmatic subjects possess stiffer, more reactive airway smooth muscle. There is evidence that one can enhance airway reactivity in healthy lungs by prohibiting DI for an extended period. The present study had two goals. First, we determined whether the maximum dilation capacity of asthmatic subjects depended on the rate of the DI. Second, we investigated whether the enhanced reactivity in healthy humans might derive from additional mechanisms not present in asthmatic subjects. For the first goal, we tracked Raw in seven healthy and seven asthmatic subjects during a noncoached DI, a DI with a 5- to 10-s breath hold at total lung capacity, and a rapid DI. We found that the minimum resistance achieved at total lung capacity was independent of the manner in which the DI was performed. For the second goal, we tracked the rate of return of Raw after a DI as well as dynamic lung elastance before and after the DI, at baseline and after bronchial challenge. A drop in lung elastance post-DI would indicate reopening of lung regions and/or reduced heterogeneities. The data show that constricted healthy but not asthmatic subjects produce longer lasting residual dilation. Hence, a portion of the enhanced reactivity in a healthy subject's response to prohibition of DIs is likely due to airway closure and/or atelectasis that can be ablated with a DI. We conclude that preventing DIs does not ensure that healthy subjects will transition entirely to an asthmatic-like hyperreactive lung state.
Enhanced Long-Term Potentiation During Aging Is Masked by Processes Involving Intracellular Calcium Stores
Authors: Kumar Ashok , Foster Thomas C.
Published: February 2004

The contribution of Ca2+ release from intracellular Ca2+ stores (ICS) for regulation of synaptic plasticity thresholds during aging was investigated in hippocampal slices of old (22–24 mo) and young adult (5–8 mo) male Fischer 344 rats. Inhibition of Ca2+-induced Ca2+ release by thapsigargin, cyclopiazonic acid (CPA), or ryanodine during pattern stimulation near the threshold for synaptic modification (5 Hz, 900 pulses) selectively induced long-term potentiation (LTP) to CA1 Schaffer collateral synapses of old rats. Increased synaptic strength was specific to test pathways and blocked by AP-5. Intracellular recordings demonstrated that ICS plays a role in the augmentation of the afterhyperpolarization (AHP) in old rats. The decrease in the AHP by ICS inhibition was reversed by the L-channel agonist, Bay K8644. Under conditions of ICS inhibition and a Bay K8644–mediated enhancement of the AHP, pattern stimulation failed to induce LTP, consistent with the idea that the AHP amplitude shapes the threshold for LTP induction. Finally, ICS inhibition was associated with an increase in the N-methyl-d-aspartate (NMDA) receptor component of synaptic transmission in old animals. This increase in the synaptic response was blocked by the calcineurin inhibitor FK506. The results reveal an age-related increase in susceptibility to LTP-induction that is normally inhibited by ICS and suggest that the age-related shift in Ca2+ regulation and Ca2+-dependent synaptic plasticity is coupled to changes in cell excitability and NMDA receptor function through ICS.
Relationship of Alcohol Intake With Inflammatory Markers and Plasminogen Activator Inhibitior-1 in Well-Functioning Older Adults
Authors: Volpato Stefano , Pahor Marco , Ferrucci Luigi , Simonsick Eleanor M. , Guralnik Jack M. , Kritchevsky Stephen B. , Fellin Renato , Harris Tamara B.
Published: February 2004

Background—

Increased levels of acute-phase reactants predict the onset of poor health outcomes. A U-shaped association has been reported between alcohol intake and health outcomes, which suggests that alcohol intake may modify levels of acute-phase reactants. We investigated the relationship between weekly alcohol intake and interleukin-6 (IL-6), C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and plasminogen activator inhibitor-1 (PAI-1).

Methods and Results—

Data are from year 1 of the Health, Aging, and Body Composition study, a biracial cohort of 3075 well-functioning men and women aged 70 to 79 years, living in Memphis, Tenn, and Pittsburgh, Pa. The analysis included 2574 persons (51.2% women; 40.1% black) with complete data. After adjustment for age, race, smoking status, history of diabetes, history of cardiovascular disease, physical activity, high-density lipoprotein cholesterol, antiinflammatory medications, statins, and total fat mass, alcohol intake showed a J-shaped relationship with mean IL-6 (
P
for quadratic term <0.001) and CRP (
P
=0.014) levels. The association was consistent in both men and women. Compared with subjects who consumed 1 to 7 drinks per week, those who never drank had an increased likelihood of having high levels of both IL-6 and CRP, as did those who drank 8 or more drinks per week. We found no relationship between alcohol intake and levels of TNF-α and PAI-1 (
P
=0.137 and 0.08, respectively).

Conclusions—

In well-functioning older persons, light alcohol consumption is associated with lower levels of IL-6 and CRP. These results might suggest an additional biological explanation to the epidemiological link between moderate alcohol consumption and cardiovascular events.
Differential Treatment Benefit of Platelet Glycoprotein IIb/IIIa Inhibition With Percutaneous Coronary Intervention Versus Medical Therapy for Acute Coronary Syndromes
Authors: Pieper Karen S. , Tsiatis Anastasios A. , Davidian Marie , Hasselblad Vic , Kleiman Neal S. , Boersma Eric , Chang Wei-Ching , Griffin Jeffrey , Armstrong Paul W. , Califf Robert M. , Harrington Robert A.
Published: February 2004

Background—

Although many believe that platelet glycoprotein IIb/IIIa inhibitors should be used only in acute coronary syndrome patients undergoing percutaneous coronary intervention, supporting data from randomized clinical trials are tenuous. The assumption that these agents are useful only in conjunction with percutaneous coronary intervention is based primarily on inappropriate subgroup analyses performed across the glycoprotein IIb/IIIa inhibitor trials.

Methods and Results—

We describe the problems with these analytical techniques and demonstrate that different approaches to the question can result in opposing answers.

Conclusions—

Clinical-practice decisions and practice guidelines should be based on overall trial results and not analyses of post-randomization subgroups.
Impact of Obesity on Plasma Natriuretic Peptide Levels
Authors: Wang Thomas J. , Larson Martin G. , Levy Daniel , Benjamin Emelia J. , Leip Eric P. , Wilson Peter W.F. , Vasan Ramachandran S.
Published: February 2004

Background—

The mechanisms linking obesity to hypertension have not been established, but sodium retention and excessive sympathetic tone are key contributors. The natriuretic peptides are important regulators of sodium homeostasis and neurohormonal activation, raising the possibility that obese individuals have an impaired natriuretic peptide response.

Methods and Results—

We examined the relations of plasma B-type natriuretic peptide (BNP) and N-terminal proatrial natriuretic peptide (N-ANP) to body mass index in 3389 Framingham Study participants (1803 women) without heart failure. Multivariable regression analyses were performed, adjusting for clinical and echocardiographic covariates. BNP levels below the assay detection limit and N-ANP levels in the lowest sex-specific quartile were categorized as low. Multivariable-adjusted mean plasma BNP levels in lean (<25 kg/m
2
), overweight (25 to 29.9 kg/m
2
), and obese (≥30 kg/m
2
) men were 21.4, 15.5, and 12.7 pg/mL, respectively (trend
P
<0.0001). Corresponding values in women were 21.1, 16.3, and 13.1 pg/mL (trend
P
<0.001). A similar pattern was noted for plasma N-ANP. Obese individuals had higher odds of having low plasma BNP (multivariable-adjusted odds ratios: men, 2.51; 95% CI, 1.71 to 3.68; women, 1.84; 95% CI, 1.32 to 2.58) and low plasma N-ANP (odds ratios: men, 4.81; 95% CI, 2.98 to 7.76; women, 2.85; 95% CI, 2.01 to 4.04) compared with lean individuals. Diabetes also was associated with low plasma natriuretic peptide levels, and the negative effects of obesity and diabetes on natriuretic peptide levels were additive.

Conclusions—

Obese individuals have low circulating natriuretic peptide levels, which may contribute to their susceptibility to hypertension and hypertension-related disorders.
Tracking Women’s Awareness of Heart Disease
Authors: Mosca Lori , Ferris Anjanette , Fabunmi Rosalind , Robertson Rose Marie
Published: February 2004

Background—

Cardiovascular disease (CVD) is the leading cause of mortality in men and women in the United States, yet prior research has shown a lack of awareness of risk among women. The purpose of this study was to assess the contemporary awareness, knowledge, and perceptions related to CVD risk among American women and to evaluate trends since 1997, when the American Heart Association initiated a national campaign to improve awareness of CVD among women.

Methods and Results—

A telephone survey of a nationally representative random sample of women was conducted in June and July 2003, with an oversampling of black and Hispanic women; results were compared with those of similar surveys in 2000 and 1997. The present survey included 1024 respondents age ≥25 years; 68% were white, 12% black, 12% Hispanic, and 8% other ethnicities. Awareness, knowledge, and perceptions about heart disease were evaluated by use of a standard interviewer-assisted questionnaire. A shift in awareness of heart disease as the leading killer of women has occurred since 1997. In 2003, 46% of respondents spontaneously identified heart disease as the leading cause of death in women, up from 30% in 1997 (
P
<0.05) and 34% in 2000 (
P
<0.05). In contrast, the percentage of women citing cancer as leading cause of death has significantly decreased. Black, Hispanic, and younger women (<45 years old) had lower awareness of heart disease as their leading cause of death than did white and older women. Nearly all women reported comfort in discussing prevention with healthcare providers, but only 38% of women reported that their doctors had ever discussed heart disease with them.

Conclusions—

Awareness of CVD has increased, although a significant gap between perceived and actual risk of CVD remains. Educational interventions to improve awareness and knowledge are needed, particularly for minority and younger women.
Dependency Parsing with an Extended Finite-State Approach
Authors: Oflazer Kemal
Published: February 2004

This article presents a dependency parsing scheme using an extended finite-state approach. The parser augments input representation with “channels” so that links representing syntactic dependency relations among words can be accommodated and iterates on the input a number of times to arrive at a fixed point. Intermediate configurations violating various constraints of projective dependency representations such as no crossing links and no independent items except sentential head are filtered via finite-state filters. We have applied the parser to dependency parsing of Turkish.
Anaphora and Discourse Structure
Authors: Webber Bonnie , Stone Matthew , Joshi Aravind , Knott Alistair
Published: February 2004

We argue in this article that many common adverbial phrases generally taken to signal a discourse relation between syntactically connected units within discourse structure instead work anaphorically to contribute relational meaning, with only indirect dependence on discourse structure. This allows a simpler discourse structure to provide scaffolding for compositional semantics and reveals multiple ways in which the relational meaning conveyed by adverbial connectives can interact with that associated with discourse structure. We conclude by sketching out a lexicalized grammar for discourse that facilitates discourse interpretation as a product of compositional rules, anaphor resolution, and inference.
Head-Driven Statistical Models for Natural Language Parsing
Authors: Collins Michael
Published: February 2004

This article describes three statistical models for natural language parsing. The models extend methods from probabilistic context-free grammars to lexicalized grammars, leading to approaches in which a parse tree is represented as the sequence of decisions corresponding to a head-centered, top-down derivation of the tree. Independence assumptions then lead to parameters that encode the X-bar schema, subcategorization, ordering of complements, placement of adjuncts, bigram lexical dependencies, wh-movement, and preferences for close attachment. All of these preferences are expressed by probabilities conditioned on lexical heads. The models are evaluated on the Penn Wall Street Journal Treebank, showing that their accuracy is competitive with other models in the literature. To gain a better understanding of the models, we also give results on different constituent types, as well as a breakdown of precision/recall results in recovering various types of dependencies. We analyze various characteristics of the models through experiments on parsing accuracy, by collecting frequencies of various structures in the treebank, and through linguistically motivated examples. Finally, we compare the models to others that have been applied to parsing the treebank, aiming to give some explanation of the difference in performance of the various models.
Disambiguating Nouns, Verbs, and Adjectives Using Automatically Acquired Selectional Preferences
Authors: McCarthy Diana , Carroll John
Published: February 2004

Selectional preferences have been used by word sense disambiguation (WSD) systems as one source of disambiguating information. We evaluate WSD using selectional preferences acquired for English adjective—noun, subject, and direct object grammatical relationships with respect to a standard test corpus. The selectional preferences are specific to verb or adjective classes, rather than individual word forms, so they can be used to disambiguate the co-occurring adjectives and verbs, rather than just the nominal argument heads. We also investigate use of the one-senseper-discourse heuristic to propagate a sense tag for a word to other occurrences of the same word within the current document in order to increase coverage. Although the preferences perform well in comparison with other unsupervised WSD systems on the same corpus, the results show that for many applications, further knowledge sources would be required to achieve an adequate level of accuracy and coverage. In addition to quantifying performance, we analyze the results to investigate the situations in which the selectional preferences achieve the best precision and in which the one-sense-per-discourse heuristic increases performance.
Visual Search and Dual Tasks Reveal Two Distinct Attentional Resources
Authors: VanRullen Rufin , Reddy Lavanya , Koch Christof
Published: February 2004

Most theories of visual processing assume that a target will “pop out” from an array of distractors (“parallel” visual search, e.g., color or orientation discrimination) if targets and distractors can be discriminated without attention. When the discrimination requires attention (e.g., rotated L vs. T or red-green vs. green-red bisected disks), “serial” examination is needed in visual search. Attentional requirements are also frequently assessed by measuring interference from a concurrently performed attentionally demanding task. It is commonly believed that attention acts equivalently in dual-task and visual search paradigms, based on the implicit assumption that visual attentional requirements can be defined along a single dimension. Here we show that there is no such equivalence: We report on targets that do not trigger pop-out, even though they can be discriminated from distractors with attention occupied elsewhere (natural scenes, color-orientation conjunctions); conversely, we show that certain targets that pop out among distractors need undivided attention to be effectively discriminated from distractors when presented in isolation (rotated L vs. +, depth-rotated cubes). In other words, visual search and dual-task performance reveal attentional resources along two independent dimensions. We suggest an interpretation of these results in terms of neuronal selectivities and receptive field size effects.
The von Restorff Effect in Amnesia: The Contribution of the Hippocampal System to Novelty-Related Memory Enhancements
Authors: Kishiyama M. M. , Yonelinas A. P. , Lazzara M. M.
Published: February 2004

The ability to detect novelty is a characteristic of all mammalian nervous systems (Sokolov, 1963), and it plays a critical role in memory in the sense that items that are novel, or distinctive, are remembered better than those that are less distinct (von Restorff, 1933). Although several brain areas are sensitive to stimulus novelty, it is not yet known which regions play a role in producing novelty-related effects on memory. In the current study, we investigated novelty effects on recognition memory in amnesic patients and healthy control subjects. The control subjects demonstrated better recognition for items that were novel (i.e., presented in an infrequent color), and this effect was found for both recollection and familiarity-based responses. However, the novelty advantage was effectively eliminated in patients with extensive medial temporal lobe damage, mild hypoxic patients expected to have relatively selective hippocampal damage, and in a patient with thalamic lesions. The results indicate that the human medial temporal lobes play a critical role in producing normal novelty effects in memory.
Visual Enhancing of Tactile Perception in the Posterior Parietal Cortex
Authors: Ro Tony , Wallace Ruth , Hagedorn Judith , Farné Alessandro , Pienkos Elizabeth
Published: February 2004

Rice University

The visual modality typically dominates over our other senses. Here we show that after inducing an extreme conflict in the left hand between vision of touch (present) and the feeling of touch (absent), sensitivity to touch increases for several minutes after the conflict. Transcranial magnetic stimulation of the posterior parietal cortex after this conflict not only eliminated the enduring visual enhancement of touch, but also impaired normal tactile perception. This latter finding demonstrates a direct role of the parietal lobe in modulating tactile perception as a result of the conflict between these senses. These results provide evidence for visual-to-tactile perceptual modulation and demonstrate effects of illusory vision of touch on touch perception through a long-lasting modulatory process in the posterior parietal cortex.
Magnetic Brain Response Mirrors Extraction of Phonological Features from Spoken Vowels
Authors: Obleser Jonas , Lahiri Aditi , Eulitz Carsten
Published: February 2004

This study further elucidates determinants of vowel perception in the human auditory cortex. The vowel inventory of a given language can be classified on the basis of phonological features which are closely linked to acoustic properties. A cortical representation of speech sounds based on these phonological features might explain the surprisingly inverse correlation between immense variance in the acoustic signal and high accuracy of speech recognition. We investigated timing and mapping of the N100m elicited by 42 tokens of seven natural German vowels varying along the phonological features tongue height (corresponding to the frequency of the first formant) and place of articulation (corresponding to the frequency of the second and third formants). Auditoryevoked fields were recorded using a 148-channel whole-head magnetometer while subjects performed target vowel detection tasks. Source location differences appeared to be driven by place of articulation: Vowels with mutually exclusive place of articulation features, namely, coronal and dorsal elicited separate centers of activation along the posterior-anterior axis. Additionally, the time course of activation as reflected in the N100m peak latency distinguished between vowel categories especially when the spatial distinctiveness of cortical activation was low. In sum, results suggest that both N100m latency and source location as well as their interaction reflect properties of speech stimuli that correspond to abstract phonological features.
Serial Position Effects in Auditory Event-related Potentials during Working Memory Retrieval
Authors: Golob Edward J. , Starr Arnold
Published: February 2004

It is established that recall of an item from a list of sequentially presented items is sensitive to the item's position in the memorized list. However, little is known about the brain mechanisms that mediate these serial position effects. Studies of working memory retrieval using event-related potentials report amplitude reductions during retrieval (auditory cortical N100, neocortical late positive wave [LPW]) as memory load increases. We tested the hypothesis that N100 and LPW amplitudes to probes are also affected by serial position. Eventrelated potentials were recorded from subjects performing an auditory working memory task. A set of one or five digits was memorized, then subjects classified a probe digit as either present or absent from the memory set. A control task was also given. Amplitudes of the N100 and LPW were reduced in the 5-item versus the 1-item set. In the 5-item set N100 amplitude was significantly larger for the initial (1st) serial position, relative to Positions 2–5, while linear increases in LPW amplitude were seen across serial positions (5th > 1st position). A control task without memorization showed no N100 or LPW amplitude changes with set size or serial position. The findings reveal that the N100 and LPW are influenced differently by serial position during working memory retrieval: N100 shows a primacy effect and LPW demonstrates a recency effect. The results suggest that primacy and recency effects may be mediated by different brain regions at different times during memory retrieval.
Posttraining Sleep Enhances Automaticity in Perceptual Discrimination
Authors: Atienza Mercedes , Cantero Jose L. , Stickgold Robert
Published: February 2004

Perceptual learning can develop over extended periods, with slow, at times sleep-dependent, improvement seen several days after training. As a result, performance can become more automatic, that is, less dependent on voluntary attention. This study investigates whether the brain correlates of this enhancement of automaticity are sleep-dependent. Event-related potentials produced in response to complex auditory stimuli were recorded while subjects' attention was focused elsewhere. We report here that following training on an auditory discrimination task, performance continued to improve, without significant further training, for 72 hr. At the same time, several event-related potential components became evident 48–72 hr after training. Posttraining sleep deprivation prevented neither the continued performance improvement nor the slow development of cortical dynamics related to an enhanced familiarity with the task. However, those brain responses associated with the automatic shift of attention to unexpected stimuli failed to develop. Thus, in this auditory learning paradigm, posttraining sleep appears to reduce the voluntary attentional effort required for successful perceptual discrimination by facilitating the intrusion of a potentially meaningful stimulus into one's focus of attention for further evaluation.
Multiple Motor Learning Experiences Enhance Motor Adaptability
Authors: Seidler Rachael D.
Published: February 2004

Traditional motor learning theory emphasizes that skill learning is specific to the context and task performed. Recent data suggest, however, that subjects exposed to a variety of motor learning paradigms may be able to acquire general, transferable knowledge about skill learning processes. I tested this idea by having subjects learn five different motor tasks, three that were similar to each other and two that were not related. A group of experimental subjects first performed a joystick-aiming task requiring adaptation to three different visuomotor rotations, with a return to the null conditions between each exposure. They then performed the same joystick-aiming task but had to adapt to a change in display gain instead of rotation. Lastly, the subjects used the joystickaiming task to learn a repeating sequence of movements. Two groups of control subjects performed the same number of trials, but learned only the gain change or the movement sequence. Experimental subjects showed generalization of learning across the three visuomotor rotations. Experimental subjects also exhibited transfer of learning ability to the gain change and the movement sequence, resulting in faster learning than that seen in the control subjects. However, transient perturbations affected the movements of the experimental subjects to a greater extent than those of the control subjects. These data demonstrate that humans can acquire a general enhancement in motor skill learning capacity through experience, but it comes with a cost. Although movement becomes more adaptable following multiple learning experiences, it also becomes less stable to external perturbation.
Patients with Right Frontal Lesions are Unable to Assess and Use Advice to Make Predictive Judgments
Authors: Gomez-Beldarrain Marian , Harries Clare , Garcia-Monco Juan Carlos , Ballus Emma , Grafman Jordan
Published: February 2004

Frontal lobe damage impairs decision-making. Most studies have employed gambling and probabilistic tasks, which have an emotional (reward-punishment) component and found that patients with ventromedial sector lesions have exceptional difficulty performing normally on these tasks. We have recently presented an economic decision-making task to patients and normal volunteers that required them to not only forecast an economic outcome but also to weigh advice from four advisors about the possible outcome across 40 trials. We studied 20 patients with right frontal lobe lesions and 9 patients with parietal lobe lesions and compared their performance to 20 matched controls. Frontal lobe lesion patients were inconsistent at using advice and their forecasts were poor. Patients with dorsolateral but not orbito-frontal lesions showed some ability to assess advice. Patients with parietal lobe lesions were good at assessing advice but were slow at doing so; they were consistent but poor at using advice and their use of advice was unrelated to their forecasting. All three patient groups were overconfident in their own performance. In contrast, controls could both use and assess advice, their ability to use advice was mediated by their ability to assess it, and they were not overconfident. Group differences on an overall measure of accuracy on this task were associated with an ability to accurately plan. Differences in ability to assess and forecast were associated with planning and working memory performance. These findings indicate that patients with both right dorsolateral and orbito-frontal lesions may be impaired when required to make complex decisions related to forecasting and judgment. Our findings enlarge the scope of decision-making deficits seen in patients with frontal lobe lesions and indicate additional circumstances in which patients with frontal lobe lesions will have difficulty in deciding.
Size Contrast and Assimilation Explained by the Statistics of Natural Scene Geometry
Authors: Howe Catherine Q. , Purves Dale
Published: February 2004

The term “size contrast and assimilation” refers to a large class of geometrical illusions in which the apparent sizes of identical visual targets in various contexts are different. Here we have examined whether these intriguing discrepancies between physical and perceived size can be explained by a visual process in which percepts are determined by the probability distribution of the possible real-world sources of retinal stimuli. To test this idea, we acquired a range image database of natural scenes that specified the location of every image point in 3-D space. By sampling the possible physical sources of various size contrast or assimilation stimuli in the database, we determined the probability distributions of the size of the target in the images generated by these sources. For each of the various stimuli tested, these probability distributions of target size in different contexts accurately predicted the perceptual effects reported in psychophysical studies. We conclude that size contrast and assimilation effects are a further manifestation of a fundamentally probabilistic process of visual perception.
The Effects of Aging on Controlled Attention and Conflict Processing in the Stroop Task
Authors: West Robert
Published: February 2004

Recent computational modeling and behavioral work indicate that age-related declines in the ability to represent task context may contribute to disruptions of working memory and selective attention in older adults. However, it is unclear whether age-related declines in context processing arise from a disruption of the encoding or maintenance of task context and how age-related declines in context processing interact with mechanisms supporting conflict detection and resolution processes contributing to efficient selection of task-relevant information. This study examines the effects of aging on the neural correlates of context and conflict processing in the Stroop task using event-related brain potentials (ERPs). Age-related differences in the time course of modulations of the ERPs associated with encoding (P3) and maintaining (slow wave) task context were observed. There were also age-related differences in the N450, conflict SP, and ERN associated with conflict processing that interacted with task context. These data indicate that aging is associated with declines in the efficiency of those neural mechanisms supporting both context and conflict processing, and that the effects of aging are not pervasive but rather interact with task context.
Neural Circuits Involved in the Recognition of Actions Performed by Nonconspecifics: An fMRI Study
Authors: Buccino Giovanni , Lui Fausta , Canessa Nicola , Patteri Ilaria , Lagravinese Giovanna , Benuzzi Francesca , Porro Carlo A. , Rizzolatti Giacomo
Published: February 2004

Functional magnetic resonance imaging was used to assess the cortical areas active during the observation of mouth actions performed by humans and by individuals belonging to other species (monkey and dog). Two types of actions were presented: biting and oral communicative actions (speech reading, lip-smacking, barking). As a control, static images of the same actions were shown. Observation of biting, regardless of the species of the individual performing the action, determined two activation foci (one rostral and one caudal) in the inferior parietal lobule and an activation of the pars opercularis of the inferior frontal gyrus and the adjacent ventral premotor cortex. The left rostral parietal focus (possibly BA 40) and the left premotor focus were very similar in all three conditions, while the right side foci were stronger during the observation of actions made by conspecifics. The observation of speech reading activated the left pars opercularis of the inferior frontal gyrus, the observation of lip-smacking activated a small focus in the pars opercularis bilaterally, and the observation of barking did not produce any activation in the frontal lobe. Observation of all types of mouth actions induced activation of extrastriate occipital areas. These results suggest that actions made by other individuals may be recognized through different mechanisms. Actions belonging to the motor repertoire of the observer (e.g., biting and speech reading) are mapped on the observer's motor system. Actions that do not belong to this repertoire (e.g., barking) are essentially recognized based on their visual properties. We propose that when the motor representation of the observed action is activated, the observer gains knowledge of the observed action in a “personal” perspective, while this perspective is lacking when there is no motor activation.
Neural Substrates of Response-based Sequence Learning using fMRI
Authors: Bischoff-Grethe Amanda , Goedert Kelly M. , Willingham Daniel T. , Grafton Scott T.
Published: February 2004

Representation of sequential structure can occur with respect to the order of perceptual events or the order in which actions are linked. Neural correlates of sequence retrieval associated with the order of motor responses were identified in a variant of the serial reaction time task in which training occurred with a spatially incompatible mapping between stimuli and finger responses. After transfer to a spatially compatible version of the task, performance enhancements indicative of learning were only present in subjects required to make finger movements in the same order used during training. In contrast, a second group of subjects performed the compatible task using an identical sequence of stimuli (and different order of finger movements) as in training. They demonstrated no performance benefit, indicating that learning was response based. Analysis was restricted to subjects demonstrating low recall of the sequence structure to rule out effects of explicit awareness. The interaction of group (motor vs. perceptual transfer) with sequence retrieval (sequencing vs. rest) revealed significantly greater activation in the bilateral supplementary motor area, cingulate motor area, ventral premotor cortex, left caudate, and inferior parietal lobule for subjects in the motor group (illustrating successful sequence retrieval at the response level). Retrieval of sequential responses occurs within mesial motor areas and related motor planning areas.