bluuebunny/crossref_metadata_2025 huggingface dataset:
Preference of Personal to Extrapersonal Space in a Visuomotor Task
Authors: Hari Riitta , Jousmäki Veikko
Published: February 2008

The speed of visually triggered movements depends, among other things, on the time needed for visuomotor transformations. We show that it takes on average 20–40 msec less time to respond to visual stimuli when they are projected on the reacting fingers than a few centimeters away from them. The result implies significant preference of the personal space to the extrapersonal space for stimuli used in the initiation of visually triggered movements.
Modeling the Temporal Dynamics of IT Neurons in Visual Search: A Mechanism for Top-Down Selective Attention
Authors: Usher Marius , Niebur Ernst
Published: February 2008

We propose a neural model for object-oriented attention in which various visual stimuli (shapes, colors, letters, etc.) are represented by competing, mutually inhibitory, cell assemblies. The model's response to a sequence of cue and target stimuli mimics the neural responses in infero temporal (IT) visual cortex of monkeys performing a visual search task: enhanced response during the display of the stimulus, which decays but remains above a spontaneous rate after the cue disappears. When, subsequently, a display consisting of the target and several distractors is presented, the activity of all stimulus-driven cells is initially enhanced. After a short period of time, however, the activity of the cell assembly representing the cue stimulus is enhanced while the activity of the distractors decays because of mutual competition and a small top-down “expectational” input. The model fits the measured delayed activity in IT-cortex, recently reported by Chelazzi, Miller, Duncan, and Desimone (1993a), and we suggest that such a process, which is largely independent of the number of distractors, may be used by the visual system for selecting an expected target (appearing at an uncertain location) among distractors.
Imaging Cognition: An Empirical Review of PET Studies with Normal Subjects
Authors: Cabeza Roberto , Nyberg Lars
Published: February 2008

We review PET studies of higher-order cognitive processes, including attention (sustained and selective), perception (of objects, faces, and locations), language (word listening, reading, and production), working memory (phonological and visuo-spatial), semantic memory retrieval (intentional and incidental), episodic memory retrieval (verbal and nonverbal), priming, and procedural memory (conditioning and skill learning). For each process, we identify activation patterns including the most consistently involved regions. These regions constitute important components of the network of brain regions that underlie each function.
Cortical Synchronization and Perceptual Framing
Authors: Grossberg Stephen , Grunewald Alexander
Published: February 2008

How does the brain group together different parts of an object into a coherent visual object representation? Different parts of an object may be processed by the brain at different rates and may thus become desynchronized. Perceptual framing is a process that resynchronizes cortical activities corresponding to the same retinal object. A neural network model is presented that is able to rapidly resynchronize desynchronized neural activities. The model provides a link between perceptual and brain data. Model properties quantitatively simulate perceptual framing data, including psychophysical data about temporal order judgments and the reduction of threshold contrast as a function of stimulus length. Such a model has earlier been used to explain data about illusory contour formation, texture segregation, shape-from-shading, 3-D vision, and cortical receptive fields. The model hereby shows how many data may be understood as manifestations of a cortical grouping process that can rapidly resynchronize image parts that belong together in visual object representations. The model exhibits better synchronization in the presence of noise than without noise, a type of stochastic resonance, and synchronizes robustly when cells that represent different stimulus orientations compete. These properties arise when fast long-range cooperation and slow short-range competition interact via nonlinear feedback interactions with cells that obey shunting equations.
Memory Encoding Following Complete Callosotomy
Authors: Jha Amishi P. , Kroll Neal E. A. , Baynes Kathleen , Gazzaniga Michael S.
Published: February 2008

Three patients with complete resection of the corpus callosum were tested in a series of memory tasks to determine the effects of callosotomy on the encoding and retrieval of information in memory. Verbal and pictorial conjunction tests were administered to measure patients' ability to consolidate the elements of a stimulus into an accurate composite memory. Patients were also tested in a paired-associate learning task to determine the consequences of callosotomy on the encoding and retrieval of associations between stimuli. Although callosotomy patients were unimpaired in the verbal conjunction task, results from both the pictorial conjunction task and the paired-associate learning task suggest that the absence of callosal cross-talk impairs encoding in these patients. In addition, the pattern of results in the paired-associate learning task suggests that callosotomy impairs retrieval processes. The role of the callosum in the formation of memory traces for nonverbal material and associations between verbal stimuli is discussed.
Spontaneous Eye Movements During Visual Imagery Reflect the Content of the Visual Scene
Authors: Brandt Stephan A. , Stark Lawrence W.
Published: February 2008

In nine naïve subjects eye movements were recorded while subjects viewed and visualized four irregularly-checkered diagrams. Scanpaths, defined as repetitive sequences of fixations and saccades were found during visual imagery and viewing. Positions of fixations were distributed according to the spatial arrangement of subfeatures in the diagrams. For a particular imagined diagrammatic picture, eye movements were closely correlated with the eye movements recorded while viewing the same picture. Thus eye movements during imagery are not random but reflect the content of the visualized scene. The question is discussed whether scanpath eye movements play a significant functional role in the process of visual imagery.
Distributed Cortical Network for Visual Attention
Authors: Knight Robert T.
Published: February 2008

The contribution of prefrontal and posterior association cortex to voluntary and involuntary visual attention was as sessed using electrophysiological techniques in patients with focal lesions in prefrontal (n = 11), temporal-parietal (n = 10), or lateral parietal cortex (n = 7). Subjects participated in a task requiring detection of designated target stimuli embedded in trains of repetitive stimuli. Infrequent and irrelevant novel visual stimuli were randomly interspersed with the target and background stimuli. Controls generated attention dependent N1 (170 msec) and N2 (243 msec) potentials maximal over extrastriate cortex. Anterior and posterior association cortex lesions reduced the amplitude of both the N1 and N2 potentials recorded over extrastriate cortex of the lesioned hemisphere. The pattern of results obtained reveals that an intrahemispheric network involving prefrontal and posterior association cortex modulates early visual processing in extrastriate regions. Voluntary target detection generated a parietal maximal P300 response (P3b) and irrelevant novel stimuli generated a more frontocentrally distributed P300 (P3a). Cortical lesions had differential effects on P3a and P3b potentials. The P3b was not significantly reduced in any cortical lesioned group. Conversely, the P3a was reduced by both prefrontal and posterior lesions with decrements most severe throughout the lesioned hemisphere. These data provide evidence that an association cortex network involving prefrontal and posterior regions is activated during orientation to novel events. The lack of a significant effect on the visual target P3b in patients with novelty P3a reductions supports the notion that different neural systems are engaged during voluntary vs involuntary atten- tion to visual stimuli.
Functional Neuroanatomy of Recall and Recognition: A PET Study of Episodic Memory
Authors: Cabeza Roberto , Kapur Shitij , Craik Fergus I. M. , McIntosh Anthony R. , Houle Sylvain , Tulving Endel
Published: February 2008

The purpose of this study was to directly compare the brain regions involved in episodic-memory recall and recognition. Changes in regional cerebral blood flow were measured by positron emission tomography while young healthy test persons were either recognizing or recalling previously studied word pairs. Reading of previously nonstudied pairs served as a reference task for subtractive comparisons. Compared to reading, both recall and recognition were associated with higher blood flow (activation) at identical sites in the right prefrontal cortex (areas 47, 45, and 10) and the anterior cingulate. Compared to recognition, recall was associated with higher activation in the anterior cingulate, globus pallidus, thalamus, and cerebellum, suggesting that these components of the cerebello-frontal pathway play a role in recall processes that they do not in recognition. Compared to recall, recognition was associated with higher activation in the right inferior parietal cortex (areas 39, 40, and 19), suggesting a larger perceptual component in recognition than in recall. Contrary to the expectations based on lesion data, the activations of the frontal regions were indistinguishable in recall and recognition. This finding is consistent with the notion that frontal activations in explicit memory tasks are related to the general episodic retrieval mode or retrieval attempt, rather than to specific mechanisms of ecphory (recovery of stored information).
The Interaction of Spatial and Object Pathways: Evidence from Balint's Syndrome
Authors: Robertson Lynn , Treisman Anne , Friedman-Hill Stacia , Grabowecky Marcia
Published: February 2008

An earlier report described a patient (RM) with bilateral parietal damage who showed severe binding problems between shape and color and shape and size (Friedman-Hill, Robertson, & Treisman, 1995). When shown two different-colored letters, RM reported a large number of illusory conjunctions (ICs) combining the shape of one letter with the color of the other, even when he was looking directly at one of them and had as long as 10 sec to respond. The lesions also produced severe deficits in locating and reaching for objects, and difficulty in seeing more than one object at a time, resulting in a neuropsychological diagnosis of Balint's syndrome or dorsal simultanagnosia. The pattern of deficits supported predictions of Treisman's Feature Integration Theory (FIT) that the loss of spatial information would lead to binding errors. They further suggested that the spatial information used in binding depends on intact parietal function.

In the present paper we extend these findings and examine other deficits in RM that would be predicted by FIT. We show that: (1) Object individuation is impaired, making it impossible for him correctly to count more than one or two objects, even when he is aware that more are present. (2) Visual search for a target defined by a conjunction of features (requiring binding) is impaired, while the detection of a target defined by a unique feature is not. Search for the absence of a feature (0 among Qs) is also severely impaired, while search for the presence (Q among 0s) is not. Feature absence can only be detected when all the present features are bound to the nontarget items. (3) RM's deficits cannot be attributed to a general binding problem: binding errors were far more likely with simultaneous presentation where spatial information was required than with sequential presentation where time could be used as the medium for binding. (4) Selection for attention was severely impaired, whether it was based on the position of a marker or on some other feature (color). (5) Spatial information seems to exist that RM cannot access, suggesting that feature binding relies on a relatively late stage where implicit spatial information is made explicitly accessible.

The data converge to support our conclusions that explicit spatial knowledge is necessary for the perception of accurately bound features, for accurate attentional selection, and for accurate and rapid search for a conjunction of features in a multiitem display. It is obviously necessary for directing attention to spatial locations, but the consequences of impairments in this ability seem also to affect object selection, object individuation, and feature integration. Thus, the functional effects of parietal damage are not limited to the spatial and attentional problems that have long been described in patients with Balint's syndrome. Damage to parietal areas also affects object perception through damage to spatial representations that are fundamental for spatial awareness.
Brain Activity Associated with Syntactic Incongruencies in Words and Pseudo-Words
Authors: Münte Thomas F. , Matzke Mike , Johannes Sönke
Published: February 2008

Event-related brain potentials (EMS) were recorded while normal German subjects read either simple declarative sen- tences made up from real German words, or sentences that contained German pseudo-words instead of nouns and verbs. The verb (pseudo-verb) of the sentences disagreed in number with the subject noun (pseudo-noun) in 50% of the sentences. The subjects had the task either to read the sentences for an interspersed memory test (memory condition, pseudeword sentences only) or to make a syntactic judgment after each real-word/pseudo-word sentence.

While in the real-word condition a late and widespread positivity resembling the previously described syntactic positive shift was found for the disagreeing verbs, a negativity with an onset latency of about 300 msec was seen for the disagreeing pseudo-verbs. In the pseudo-word conditions no positivity followed the initial negativity. This dissociation of negative and positive waves occurring in response to morphosyntactic mismatches by the pseudo/real-word manipulation suggests that the positive shift is a concomitant of a recomputation routine initiated to account for the number incongruency. This routine is based upon the semantics of the sentence and therefore is not observed in the pseudo-word conditions. The earlier negativity, on the other hand, appears to be a more direct index of morphosyntactic incongruency.
Verbal Working Memory Load Affects Regional Brain Activation as Measured by PET
Authors: Jonides John , Schumacher Eric H. , Smith Edward E. , Lauber Erick J. , Awh Edward , Minoshima Satoshi , Koeppe Robert A.
Published: February 2008

We report an experiment that assesses the effect of variations in memory load on brain activations that mediate verbal working memory. The paradigm that forms the basis of this experiment is the “n-back” task in which subjects must decide for each letter in a series whether it matches the one presented n items back in the series. This task is of interest because it recruits processes involved in both the storage and manipulation of information in working memory. Variations in task difficulty were accomplished by varying the value of n. As n increased, subjects showed poorer behavioral performance as well as monotonically increasing magnitudes of brain activation in a large number of sites that together have been identified with verbal working-memory processes. By contrast, there was no reliable increase in activation in sites that are unrelated to working memory. These results validate the use of parametric manipulation of task variables in neuroimaging research, and they converge with the subtraction paradigm used most often in neuroimaging. In addition, the data support a model of working memory that includes both storage and executive processes that recruit a network of brain areas, all of which are involved in task performance.
Effects of Early and Late Nocturnal Sleep on Declarative and Procedural Memory
Authors: Plihal Werner , Born Jan
Published: February 2008

Recall of paired-associate lists (declarative memory) and mirror-tracing skills (procedural memory) was assessed after retention intervals defined over early and late nocturnal sleep. In addition, effects of sleep on recall were compared with those of early and late retention intervals filled with wakefulness. Twenty healthy men served as subjects. Saliva cortisol concentrations were determined before and after the retention intervals to determine pituitary-adrenal secretory activity. Sleep was determined somnopolygraphically. Sleep generally enhanced recall when compared with the effects of corresponding retention intervals of wakefulness. The benefit from sleep on recall depended on the phase of sleep and on the type of memory: Recall of paired-associate lists improved more during early sleep, and recall of mirror-tracing skills improved more during late sleep. The effects may reflect different influences of slow wave sleep (SWS) and rapid eye movement (REM) sleep since time in SWS was 5 times longer during the early than late sleep retention interval, and time in REM sleep was twice as long during late than early sleep (p < 0.005). Changes in cortisol concentrations, which independently of sleep and wakefulness were lower during early retention intervals than late ones, cannot account for the effects of sleep on memory. The experiments for the first time dissociate specific effects of early and late sleep on two principal types of memory, declarative and procedural, in humans.
Parents of Children with Asperger Syndrome: What is the Cognitive Phenotype?
Authors: Baron-Cohen Simon , Hammer Jessica
Published: February 2008

Two cognitive anomalies have been found in autism: a superiority on the Embedded Figures Task and a deficit in “theory of mind.” Using adult-level versions of these tasks, the present study investigated if parents of children with Asperger Syndrome might show a mild variant of these anomalies, as might be predicted from a genetic hypothesis. Significant differences were found on both measures. Parents were significantly faster than controls on the Embedded Figures Task and slightly but significantly less accurate at interpreting photographs of the eye region of the face in terms of mental states. The results are discussed in terms of the broader cognitive phenotype of Asperger Syndrome and in terms of their implications for cognitive neuroscientific theories of the condition.
Face-Specific Processing in the Human Fusiform Gyrus
Authors: McCarthy Gregory , Puce Aina , Gore John C. , Allison Truett
Published: February 2008

The perception of faces is sometimes regarded as a specialized task involving discrete brain regions. In an attempt to identi$ face-specific cortex, we used functional magnetic resonance imaging (fMRI) to measure activation evoked by faces presented in a continuously changing montage of common objects or in a similar montage of nonobjects. Bilateral regions of the posterior fusiform gyrus were activated by faces viewed among nonobjects, but when viewed among objects, faces activated only a focal right fusiform region. To determine whether this focal activation would occur for another category of familiar stimuli, subjects viewed flowers presented among nonobjects and objects. While flowers among nonobjects evoked bilateral fusiform activation, flowers among objects evoked no activation. These results demonstrate that both faces and flowers activate large and partially overlapping regions of inferior extrastriate cortex. A smaller region, located primarily in the right lateral fusiform gyrus, is activated specifically by faces.
How Do Monkeys Look at Faces?
Authors: Nahm Frederick K. D. , Perret Amelie , Amaral David G. , Albright Thomas D.
Published: February 2008

Facial displays are an important form of social communication in nonhuman primates. Clues to the information conveyed by faces are the temporal and spatial characteristics of ocular viewing patterns to facial images. The present study compares viewing patterns of four rhesus monkeys (Macaca mulatta) to a set of 1- and 3-sec video segments of conspecific facial displays, which included open-mouth threat, lip-smack, yawn, fear-grimace, and neutral profile. Both static and dynamic video images were used. Static human faces displaying open-mouth threat, smile, and neutral gestures were also presented. Eye position was recorded with a surgically implanted eye-coil. The relative perceptual salience of the eyes, the midface, and the mouth across different expressive gestures was determined by analyzing the number of eye movements associated with each feature during static and dynamic presentations. The results indicate that motion does not significantly affect the viewing patterns to expressive facial displays, and when given a choice, monkeys spend a relatively large amount of time inspecting the face, especially the eyes, as opposed to areas surrounding the face. The expressive nature of the facial display also affected viewing patterns in that threatening and fear-related displays evoked a pattern of viewing that differed from that recorded during the presentation of submissive-related facial displays. From these results we conclude that (1) the most important determinant of the visual inspection patterns of faces is the constellation of physiognomic features and their configuration, but not facial motion, (2) the eyes are generally the most salient facial feature, and (3) the agonistic or affiliative dimension of an expressive facial display can be delineated on the basis of viewing patterns.
Intact Priming for Novel Perceptual Representations in Amnesia
Authors: Hamann Stephan B. , Squire Larry R.
Published: February 2008

Recent studies have challenged the notion that priming for ostensibly novel stimuli such as pseudowords (REAB) reflects the creation of new representations. Priming for such stimuli could instead reflect the activation of familiar memory representations that are orthographically similar (READ) and/or the activation of subparts of stimuli (RE, EX, AR), which are familar because they occur commonly in English. We addressed this issue in three experiments that assessed perceptual identification priming and recognition memory for novel and familiar letter strings in amnesic patients and control subjects. Priming for words, pseudowords, and orthographically illegal nonwords was fully intact in the amnesic patients following a single exposure, whereas recognition memory was impaired for the same items. Thus, priming can occur for stimuli that are unlikely to have preexisting representations. Words and pseudowords exhibited twice as much priming as illegal nonwords, suggesting that activation may contribute to priming for words and wordlike stimuli. Additional results showed that priming for illegal nonwords resulted from the formation of new perceptual associations among the component letters of each nonword rather than the activation of individual letter representations. In summary, the results demonstrate that priming following a single exposure can depend on the creation of new perceptual representations and that such priming is independent of the brain structures essential for declarative memory.
Segregating Semantic from Phonological Processes during Reading
Authors: Price C. J. , Moore C. J. , Humphreys G. W. , Wise R. J. S.
Published: February 2008

A number of previous functional neuroimaging studies have linked activation of the left inferior frontal gyms with semantic processing, yet damage to the frontal lobes does not critically impair semantic knowledge. This study distinguishes between semantic knowledge and the strategic processes required to make verbal decisions. Using positron emission tomography (PET), we identify the neural correlates of semantic knowledge by contrasting semantic decision on visually presented words to phonological decision on the same words. Both tasks involve identical stimuli and a verbal decision on central lingual codes (semantics and phonology), but the explicit task demands directed attention either to meaning or to the segmentation of phonology. Relative to the phonological task, the semantic task was associated with activations in left extrasylvian temporal cortex with the highest activity in the left temporal pole and a posterior region of the left middle temporal cortex (BA 39) close to the angular gyrus. The reverse contrast showed increased activity in both supramarginal gyri, the left precentral sulcus, and the cuneus with a trend toward enhanced activation in the inferior frontal cortex. These results fit well with neuropsychological evidence, associating semantic knowledge with the extrasylvian left temporal cortex and the segmentation of phonology with the perisylvian cortex.
Effects of Memory Load and Distraction on Performance and Event-Related Slow Potentials in a Visuospatial Working Memory Task
Authors: Geffen Gina M. , Wright Margaret J. , Green Heather J. , Gillespie Nicole A. , Smyth David C. , Evans David M. , Geffen Laurence B.
Published: February 2008

Brain electrical activity related to working memory was recorded at 15 scalp electrodes during a visuospatial delayed response task. Participants (N = 18) touched the remembered position of a target on a computer screen after either a 1 or 8 sec delay. These memory trials were compared to sensory trials in which the target remained present throughout the delay and response periods. Distractor stimuli identical to the target were briefly presented during the delay on 30% of trials. Responses were less accurate in memory than sensory trials, especially after the long delay. During the delay slow potentials developed that were significantly more negative in memory than sensory trials. The difference between memory and sensory trials was greater at anterior than posterior electrodes. On trials with distractors, the slow potentials generated by memory trials showed further enhancement of negativity, whereas there were minimal effects on accuracy of performance. The results provide evidence that engagement of visuospatial working memory generates slow wave negativity with a timing and distribution consistent with frontal activation. Enhanced brain activity associated with working memory is required to maintain performance in the presence of distraction.
Word, Pseudoword, and Nonword Processing: A Multitask Comparison Using Event-Related Brain Potentials
Authors: Ziegler Johannes C. , Besson Mireille , Jacobs Arthur M. , Nazir Tatjana A. , Carr Thomas H.
Published: February 2008

Event-related brain potentials (ERPs) to words, pseudowords, and nonwords were recorded in three different tasks. A letter search task was used in Experiment 1. Performance was affected by whether the target letter occurred in a word, a pseudoword, or a random nonword. ERP results corroborated the behavioral results, showing small but reliable ERP differences between the three stimulus types. Words and pseudowords differed from nonwords at posterior sites, whereas words differed from pseudowords and nonwords at anterior sites. Since deciding whether the target letter was present or absent co-occurred with stimulus processing in Experiment 1, a delayed letter search task was used in Experiment 2. ERPs to words and pseudowords were similar and differed from ERPs to nonwords, suggesting a primary role of orthographic and phonological processing in the delayed letter search task. To increase semantic processing, a categorization task was used in Experiment 3. Early differences between ERPs to words and pseudowords at left posterior and anterior locations suggested a rapid activation of lexico-semantic information. These findings suggest that the use of ERPs in a multiple task design makes it possible to track the time course and the activation of multiple sources of linguistic information when processing words, pseudowords, and nonwords. The task-dependent nature of the effects suggests that the language system can use multiple sources of linguistic information in flexible and adaptive ways.
Individual Differences in Inference Generation: An ERP Analysis
Authors: George Marie St. , Mannes Suzanne , Hoffman James E.
Published: February 2008

Readers routinely draw inferences with remarkable efficiency and seemingly little cognitive effort. The present study was designed to explore different types of inferences during the course of reading, and the potential effects of differing levels of working memory capacity on the likelihood that inferences would be made. The electroencephalogram (EEG) was recorded from five scalp sites while participants read 90 paragraphs, composed of 60 experimental paragraphs and 30 filler paragraphs. Each experimental paragraph was four sentences long, and the final sentence stated explicitly the inference that readers did or did not make. There were four types of experimental paragraphs: (1) Bridging inference, (2) Elaborative inference, (3) Word-Based Priming control, and (4) No Inference control. Participants were tested using the Daneman and Carpenter (1980) Reading Span Task and categorized as having low or high working memory capacity. The average peaks of the N400 component of the event-related brain potential (EM) were used as a measure of semantic priming and integration, such that the lower the N400 was in response to the explicitly stated inference concept, the more likely it was that the reader made the inference. Results indicate that readers with high working memory capacity made both bridging (necessary) and elaborative (optional) inferences during reading, whereas readers with low working memory capacity made only bridging inferences during reading. We interpret the findings within the framework of the Capacity Constrained Comprehension model of Just and Carpenter (1992).
Event-Related Brain Potentials Following Incorrect Feedback in a Time-Estimation Task: Evidence for a “Generic” Neural System for Error Detection
Authors: Miltner Wolfgang H. R. , Braun Christoph H. , Coles Michael G. H.
Published: February 2008

We examined scalp-recorded event-related potentials following feedback stimuli in a time-estimation task. Six hundred msec after indicating the end of a 1 sec interval, subjects received a visual, auditory, or somatosensory stimulus that indicated whether the interval they had produced was correct. Following feedback indicating incorrect performance, a negative deflection occurred, whose characteristics corresponded closely to those of the component (the error-related negativity) that accompanies errors in choice reaction time tasks. Furthermore, equivalent dipole analysis suggested that, for all three modalities, the distribution of the scalp potential was consistent with a local source in the anterior cingulate cortex or a more distributed source in the supplementary motor areas. These loci correspond closely to those described previously for the error-related negativity. We conclude that the error-related negativity is the manifestation of the activity of a “generic” neural system involved in error detection.
A Developmental Functional MRI Study of Prefrontal Activation during Performance of a Go-No-Go Task
Authors: Casey B. J. , Trainor Rolf J. , Orendi Jennifer L. , Schubert Anne B. , Nystrom Leigh E. , Giedd Jay N. , Castellanos F. Xavier , Haxby James V. , Noll Douglas C. , Cohen Jonathan D. , Forman Steven D. , Dahl Ronald E. , Rapoport Judith L.
Published: February 2008

This study examines important developmental differences in patterns of activation in the prefrontal cortex during performance of a Go-No-Go paradigm using functional magnetic resonance imaging (fMRI). Eighteen subjects (9 children and 9 adults) were scanned using gradient echo, echo planar imaging during performance of a response inhibition task. The results suggest four general findings. First, the location of activation in the prefrontal cortex was not different between children and adults, which is similar to our earlier pediatric fMRI results of prefrontal activation during a working memory task (Casey et al., 1995). Second, the volume of activation was significantly greater for children relative to adults. These differences in volume of activation were observed predominantly in the dorsal and lateral prefrontal cortices. Third, although inhibitory processes have typically been associated with more ventral or orbital frontal regions, the current study revealed activation that was distributed across both dorsolateral and orbitofrontal cortices. Finally, consistent with animal and human lesion studies, activity in orbital frontal and anterior cingulate cortices correlated with behavioral performance (i.e., number of false alarms). These results further demonstrate the utility of this methodology in studying pediatric populations.
Harmonizing the Resistance, Resisting the Harmony: A Critical Discourse on the Reconstruction of Indigenous Theory of Gender Justice in Hong Kong
Authors: Chiu Man-Chung
Published: February 2008

In Hong Kong, even though the Bill of Rights Ordinance (the localized version of ICCPR), Sex Discrimination Ordinance and a series of legal reforms were enacted and introduced respectively in 1991 and 1994, gender discrimination in legal discourse still persists. Chinese customary law, which only recognises the male's right to build small houses in the New Territories, remains an exception under the Sex Discrimination Ordinance; and the oppression of (female) sex workers is not yet recognized. Some politicians argue that discrimination is inherent in the Han-Chinese culture of harmony, which is impossible to understand from the Euro-American individual-centric perspective of gender equality. They further quote Daoist YIN-YANG cosmology where YANG/Male/Masculinity is supreme; and Confucian Constant Virtues where women are marginalized as examples showing that Han-Chinese culture, where harmony is hegemonized, cannot tolerate or accept gender equality. This paper adopts a critical perspective in examining the above arguments and points out not only that a “pure” version of patriarchal socio-legal culture in the name of harmony hegemony does not exist, but (indigenous) culture should always be meticulously and critically represented in order to reproduce “justice”. I would also argue that it is possible to scrutinize and explore the spaces of resistance within the Hong Kong Han-Chinese socio-legal culture, where foreign theories of gender justice/equality and related legal reforms can be examined.
Aerosol Influence on Mixed-Phase Clouds in CAM-Oslo
Authors: Storelvmo Trude , Kristjánsson Jón Egill , Lohmann Ulrike
Published: February 2008

A new treatment of mixed-phase cloud microphysics has been implemented in the general circulation model, Community Atmosphere Model (CAM)-Oslo, which combines the NCAR CAM2.0.1 and a detailed aerosol module. The new treatment takes into account the aerosol influence on ice phase initiation in stratiform clouds with temperatures between 0° and −40°C. Both supersaturation and cloud ice fraction, that is, the fraction of cloud ice compared to the total cloud water in a given grid box, are now determined based on a physical reasoning in which not only temperature but also the ambient aerosol concentration play a role. Included in the improved microphysics treatment is also a continuity equation for ice crystal number concentration. Ice crystal sources are heterogeneous and homogeneous freezing processes and ice multiplication. Sink terms are collection processes and precipitation formation, that is, melting and sublimation. Instead of using an idealized ice nuclei concentration for the heterogeneous freezing processes, a common approach in global models, the freezing processes are here dependent on the ability of the ambient aerosols to act as ice nuclei. Additionally, the processes are dependent on the cloud droplet number concentration and hence the aerosols’ ability to act as cloud condensation nuclei. Sensitivity simulations based on the new microphysical treatment of mixed-phase clouds are presented for both preindustrial and present-day aerosol emissions. Freezing efficiency is found to be highly sensitive to the amount of sulphuric acid available for ice nuclei coating. In the simulations, the interaction of anthropogenic aerosols and freezing mechanisms causes a warming of the earth–atmosphere system, counteracting the cooling effect of aerosols influencing warm clouds. The authors find that this reduction of the total aerosol indirect effect amounts to 50%–90% for the specific assumptions on aerosol properties used in this study. However, many microphysical processes in mixed-phase clouds are still poorly understood and the results must be interpreted with that in mind.
Application of the Lighthill–Ford Theory of Spontaneous Imbalance to Clear-Air Turbulence Forecasting
Authors: Knox John A. , McCann Donald W. , Williams Paul D.
Published: February 2008

A new method of clear-air turbulence (CAT) forecasting based on the Lighthill–Ford theory of spontaneous imbalance and emission of inertia–gravity waves has been derived and applied on episodic and seasonal time scales. A scale analysis of this shallow-water theory for midlatitude synoptic-scale flows identifies advection of relative vorticity as the leading-order source term. Examination of leading- and second-order terms elucidates previous, more empirically inspired CAT forecast diagnostics. Application of the Lighthill–Ford theory to the Upper Mississippi and Ohio Valleys CAT outbreak of 9 March 2006 results in good agreement with pilot reports of turbulence. Application of Lighthill–Ford theory to CAT forecasting for the 3 November 2005–26 March 2006 period using 1-h forecasts of the Rapid Update Cycle (RUC) 2 1500 UTC model run leads to superior forecasts compared to the current operational version of the Graphical Turbulence Guidance (GTG1) algorithm, the most skillful operational CAT forecasting method in existence. The results suggest that major improvements in CAT forecasting could result if the methods presented herein become operational.
On the Parameterization of Evaporation of Raindrops as Simulated by a One-Dimensional Rainshaft Model
Authors: Seifert Axel
Published: February 2008

The process of evaporation of raindrops below cloud base is investigated by numerical simulations using a one-dimensional rainshaft model with bin microphysics. The simulations reveal a high variability of the shape of the raindrop size distributions, which has important implications for the efficiency of evaporation below cloud base.

A new parameterization of the shape of the raindrop size distribution as a function of the mean volume diameter is suggested and applied in a two-moment microphysical scheme. In addition, the effect of evaporation on the number concentration of raindrops is parameterized. A comparison of results of the revised two-moment scheme and the bin microphysics rainshaft model shows that the two-moment scheme is able to reproduce the results of the reference model in a wide parameter range.
Modeling Pulse-to-Pulse Coherent Doppler Sonar
Authors: Zedel L.
Published: February 2008

Coherent Doppler sonar provides a powerful tool for probing boundary layer flows under field and laboratory conditions. However, velocity profiling applications of this technique are complicated by characteristic velocity and range ambiguities. Proper implementation for any application requires careful design so that performance can be accurately predicted. In this paper, a computer model capable of simulating coherent Doppler operation is presented. The point scatterer model operates in three dimensions and accommodates bistatic transducer geometries. Excellent agreement is demonstrated between model simulations and laboratory trials. Some simple model applications are presented. The model has been developed for profiling applications but is equally suited to modeling point measurement acoustic Doppler velocimeters.
Decadal Climate Simulations Using Accurate and Fast Neural Network Emulation of Full, Longwave and Shortwave, Radiation
Authors: Krasnopolsky Vladimir M. , Fox-Rabinovitz Michael S. , Belochitski Alexei A.
Published: February 2008

An approach to calculating model physics using neural network emulations, previously proposed and developed by the authors, has been implemented in this study for both longwave and shortwave radiation parameterizations, or to the full model radiation, the most time-consuming component of model physics. The developed highly accurate neural network emulations of the NCAR Community Atmospheric Model (CAM) longwave and shortwave radiation parameterizations are 150 and 20 times as fast as the original/control longwave and shortwave radiation parameterizations, respectively. The full neural network model radiation was used for a decadal climate model simulation with the NCAR CAM. A detailed comparison of parallel decadal climate simulations performed with the original NCAR model radiation parameterizations and with their neural network emulations is presented. Almost identical results have been obtained for the parallel decadal simulations. This opens the opportunity of using efficient neural network emulations for the full model radiation for decadal and longer climate simulations as well as for weather prediction.
Effects of Accessibility and Subjective Relevance on the Use of Piecemeal and Category Information in Impression Formation
Authors: Köpetz Catalina , Kruglanski Arie W.
Published: February 2008

Three studies investigated the process by which categorical and individuating information impacts impression formation. The authors assumed that (a) both types of information are functionally equivalent in serving as evidence for interpersonal judgments and (b) their use is determined by their accessibility and perceived applicability to the impression's target. The first study constituted an extended replication of Pavelchak's experiment, and it showed that its results, initially interpreted to suggest the primacy in impression formation of category over trait information, may have been prompted by differential accessibility of the category versus trait information in some experimental conditions of the original research. Studies 2 and 3 additionally explored the role of informational accessibility manipulated in different ways. Study 3 demonstrated also that the effect of accessibility is qualified by the information's apparent relevance to the judgmental target.
Household Context and Subjective Well-Being Among the Oldest Old in China
Authors: Feinian Chen  , Short Susan E.
Published: February 2008

This article investigates the importance of household context to subjective well-being among the oldest old (aged 80 years and older) in China. Using data from the Chinese Longitudinal Healthy Longevity Survey, the authors find that living arrangements have strong implications for elderly emotional health. First, living alone is associated with lower subjective well-being. Second, coresidence with immediate family (spouse or children) is associated with positive subjective well-being. Third, compared to living with a son, the traditionally dominant type of living arrangement, coresidence with a daughter appears positively linked to the emotional health of the oldest old. Results highlight the importance of family and cultural context to subjective well-being of the oldest old. They also suggest that the gendered nature of caregiving merits further attention in China and other patrilineal societies.
The —1019 C/G polymorphism of the 5-HT1A receptor gene is associated with negative symptom response to risperidone treatment in schizophrenia patients
Authors: Wang L. , Fang C. , Zhang A. , Du J. , Yu L. , Ma J. , Feng G. , Xing Q. , He L.
Published: February 2008

The application of pharmacogenetics is currently one of the most promising developments in anti-psychotic treatment and is attracting more and more attention. Although risperidone belongs to the first-line atypical anti-psychotics, there have been relatively few risperidone pharmacogenetic studies, especially in Asian populations. We investigated the relationship between the C825T polymorphism of GBN3 (rs5443) and the —1019 C/G polymorphism of 5-HT1A (rs6295) and response to risperidone treatment. One-hundred and thirty schizophrenia patients were recruited. They were treated with risperidone monotherapy for eight weeks. Clinical response was assessed on the Positive and Negative Syndrome Scale (PANSS) on the day of admission and was subsequently assessed after eight weeks following the treatment. Patients were genotyped for two functional polymorphisms: C825T of GBN3 (rs5443) and —1019 C/G of HT1A (rs6295). Association tests between genotypes and percentage improvement in total PANSS scores, as well as positive symptom scores and negative symptom scores, were performed using analyses of variance (ANOVA). The —1019 C/G polymorphism of HT1A (rs6295) was associated with negative symptom response to treatment. Patients with the CC genotype showed substantial improvement as regards negative symptom response ( F = 4.177, df = 2, P = 0.019), compared with the patients with the CG and GG genotypes. No association was observed between C825T of GBN3 (rs5443) and changes in PANSS scores. The results suggest that the —1019 C/G polymorphism (rs6295) in the 5-HT1A gene may be a useful predictor of reduction in negative symptoms in schizophrenic patients treated with risperidone.
Ethnicity and psychopharmacology
Authors: Chaudhry IB , Neelam K. , Duddu V. , Husain N.
Published: February 2008

Ethnicity is reported to be an important, but often ignored factor in psychopharmacology. However, recent advances in molecular biology and the vision of 'personalised medicine' have spurred a debate on the role of ethnicity in this field. This paper reviews literature on the role of race and ethnicity in psychopharmacology. Despite considerable controversy on what the concepts of ethnicity and race actually measure, they are considered as important proxies for a person's culture, diet, beliefs, health behaviours and societal attitudes. Research has shown ethnic differences in the clinical presentation, treatment, clinical response and outcome of mental illnesses. A number of ethnically specific variations have been found in the genetic and non-genetic mechanisms affecting pharmacokinetics and dynamics of psychotropic drugs, which might underlie the previously mentioned differences in drug use and response across ethnicities. Although some of these ethnic differences could be partially explained by genetic factors, a number of ethnically based variables like culture, diet and societal attitudes could potentially have a significant, but as yet unquantified influence as well. Future research needs to address the problems with defining and accurately measuring 'ethnicity', as well as focus upon conducting studies that could guide treatments for people from diverse backgrounds.