Dynamic knowledge representation in connectionist systems

One of the most pervading concepts underlying computational models of information processing in the brain is linear input integration of rate coded uni-variate information by neurons. After a suitable learning process this results in neuronal structures that statically represent knowledge as a vector of real valued synaptic weights. Although this general framework has contributed to the many successes of connectionism, in this paper we argue that for all but the most basic of cognitive processes, a more complex, multi-variate dynamic neural coding mechanism is required - knowledge should not be spacially bound to a particular neuron or group of neurons. We conclude the paper with discussion of a simple experiment that illustrates dynamic knowledge representation in a spiking neuron connectionist system.

Motion estimation through approximated densities

Many techniques are currently used for motion estimation. In the block-based approaches the most common procedure applied is the block-matching based on various algorithms. To refine the motion estimates resulting from the full search or any coarse search algorithm, one can find few applications of Kalman filtering, mainly in the intraframe scheme. The Kalman filtering technique applicability for block-based motion estimation is rather limited due to discontinuities in the dynamic behaviour of the motion vectors. Therefore, we propose an application of the concept of the filtering by approximated densities (FAD). The FAD, originally introduced to alleviate limitations due to conventional Kalman modelling, is applied to interframe block-motion estimation. This application uses a simple form of FAD involving statistical characteristics of multi-modal distributions up to second order.

A comparative study of multilayered and single layered neural network based predictive controllers

The authors compare the performance of two types of controllers one based on the multilayered network and the other based on the single layered CMAC network (cerebellar model articulator controller). The neurons (information processing units) in the multi-layered network use Gaussian activation functions. The control scheme which is considered is a predictive control algorithm, along the lines used by Willis et al. (1991), Kambhampati and Warwick (1991). The process selected as a test bed is a continuous stirred tank reactor. The reaction taking place is an irreversible exothermic reaction in a constant volume reactor cooled by a single coolant stream. This reactor is a simplified version of the first tank in the two tank system given by Henson and Seborg (1989).

Conceptual representation in bilinguals: the role of language specificity and conceptual change

Most prominent models of bilingual representation assume a degree of interconnection or shared representation at the conceptual level. However, in the context of linguistic and cultural specificity of human concepts, and given recent findings that reveal a considerable amount of bidirectional conceptual transfer and conceptual change in bilinguals, a particular challenge that bilingual models face is to account for non-equivalence or partial equivalence of L1 and L2 specific concepts in bilingual conceptual store. The aim of the current paper is to provide a state-of-the-art review of the available empirical evidence from the fields of psycholinguistics, cognitive, experimental, and cross-cultural psychology, and discuss how these may inform and develop further traditional and more recent accounts of bilingual conceptual representation. Based on a synthesis of the available evidence against theoretical postulates of existing models, I argue that the most coherent account of bilingual conceptual representation combines three fundamental assumptions. The first one is the distributed, multi-modal nature of representation. The second one concerns cross-linguistic and cross-cultural variation of concepts. The third one makes assumptions about the development of concepts, and the emergent links between those concepts and their linguistic instantiations.

Information and predictability: bookmakers, prediction markets and tipsters as forecasters

The more information is available, and the more predictable are events, the better forecasts ought to be. In this paper forecasts by bookmakers, prediction markets and tipsters are evaluated for a range of events with varying degrees of predictability and information availability. All three types of forecast represent different structures of information processing and as such would be expected to perform differently. By and large, events that are more predictable, and for which more information is available, do tend to be forecast better.

Coupling between gamma-band power and cerebral blood volume during recurrent acute neocortical seizures

Characterization of neural and hemodynamic biomarkers of epileptic activity that can be measured using noninvasive techniques is fundamental to the accurate identification of the epileptogenic zone (EZ) in the clinical setting. Recently, oscillations at gamma-band frequencies and above (N30 Hz) have been suggested to provide valuable localizing information of the EZ and track cortical activation associated with epileptogenic processes. Although a tight coupling between gamma-band activity and hemodynamic-based signals has been consistently demonstrated in non-pathological conditions, very little is known about whether such a relationship is maintained in epilepsy and the laminar etiology of these signals. Confirmation of this relationship may elucidate the underpinnings of perfusion-based signals in epilepsy and the potential value of localizing the EZ using hemodynamic correlates of pathological rhythms. Here, we use concurrent multi-depth electrophysiology and 2- dimensional optical imaging spectroscopy to examine the coupling between multi-band neural activity and cerebral blood volume (CBV) during recurrent acute focal neocortical seizures in the urethane-anesthetized rat. We show a powerful correlation between gamma-band power (25–90 Hz) and CBV across cortical laminae, in particular layer 5, and a close association between gamma measures and multi-unit activity (MUA). Our findings provide insights into the laminar electrophysiological basis of perfusion-based imaging signals in the epileptic state and may have implications for further research using non-invasive multi-modal techniques to localize epileptogenic tissue

Multi-sensory treatment for children with developmental motor speech disorders

What this paper adds? What is already known on the subject? Multi-sensory treatment approaches have been shown to impact outcome measures positively, such as accuracy of speech movement patterns and speech intelligibility in adults with motor speech disorders, as well as in children with apraxia of speech, autism and cerebral palsy. However, there has been no empirical study using multi-sensory treatment for children with speech sound disorders (SSDs) who demonstrate motor control issues in the jaw and orofacial structures (e.g. jaw sliding, jaw over extension, inadequate lip rounding/retraction and decreased integration of speech movements). What this paper adds? Findings from this study indicate that, for speech production disorders where both the planning and production of spatiotemporal parameters of movement sequences for speech are disrupted, multi-sensory treatment programmes that integrate auditory, visual and tactile–kinesthetic information improve auditory and visual accuracy of speech production. The training (practised in treatment) and test words (not practised in treatment) both demonstrated positive change in most participants, indicating generalization of target features to untrained words. It is inferred that treatment that focuses on integrating multi-sensory information and normalizing parameters of speech movements is an effective method for treating children with SSDs who demonstrate speech motor control issues.

Individual differences in some (but not all) medial prefrontal regions reflect cognitive demand while regulating unpleasant emotion.

The present study investigated the premise that individual differences in autonomic physiology could be used to specify the nature and consequences of information processing taking place in medial prefrontal regions during cognitive reappraisal of unpleasant pictures. Neural (blood oxygenation level-dependent functional magnetic resonance imaging) and autonomic (electrodermal [EDA], pupil diameter, cardiac acceleration) signals were recorded simultaneously as twenty-six older people (ages 64–66 years) used reappraisal to increase, maintain, or decrease their responses to unpleasant pictures. EDA was higher when increasing and lower when decreasing compared to maintaining. This suggested modulation of emotional arousal by reappraisal. By contrast, pupil diameter and cardiac acceleration were higher when increasing and decreasing compared to maintaining. This suggested modulation of cognitive demand. Importantly, reappraisal-related activation (increase, decrease > maintain) in two medial prefrontal regions (dorsal medial frontal gyrus and dorsal cingulate gyrus) was correlated with greater cardiac acceleration (increase, decrease > maintain) and monotonic changes in EDA (increase > maintain > decrease). These data indicate that these two medial prefrontal regions are involved in the allocation of cognitive resources to regulate unpleasant emotion, and that they modulate emotional arousal in accordance with the regulatory goal. The emotional arousal effects were mediated by the right amygdala. Reappraisal-related activation in a third medial prefrontal region (subgenual anterior cingulate cortex) was not associated with similar patterns of change in any of the autonomic measures, thus highlighting regional specificity in the degree to which cognitive demand is reflected in medial prefrontal activation during reappraisal.

In-street wind direction variability in the vicinity of a busy intersection in central London

We present results from fast-response wind measurements within and above a busy intersection between two street canyons (Marylebone Road and Gloucester Place) in Westminster, London taken as part of the DAPPLE (Dispersion of Air Pollution and Penetration into the Local Environment; www.dapple.org.uk) 2007 field campaign. The data reported here were collected using ultrasonic anemometers on the roof-top of a building adjacent to the intersection and at two heights on a pair of lamp-posts on opposite sides of the intersection. Site characteristics, data analysis and the variation of intersection flow with the above-roof wind direction (θref) are discussed. Evidence of both flow channelling and recirculation was identified within the canyon, only a few metres from the intersection for along-street and across-street roof-top winds respectively. Results also indicate that for oblique rooftop flows, the intersection flow is a complex combination of bifurcated channelled flows, recirculation and corner vortices. Asymmetries in local building geometry around the intersection and small changes in the background wind direction (changes in 15-min mean θref of 5–10 degrees) were also observed to have profound influences on the behaviour of intersection flow patterns. Consequently, short time-scale variability in the background flow direction can lead to highly scattered in-street mean flow angles masking the true multi-modal features of the flow and thus further complicating modelling challenges.

Role of knowledge in managing construction change

Purpose-Unplanned changes in construction projects are common and lead to disruptive effects such as project delays, cost overruns and quality deviations. Rework due to unplanned changes can cost 10-15 per cent of contract value. By managing these changes more effectively, these disruptive effects can be minimised. Previous research has approached this problem from an information-processing view. In this knowledge age, the purpose of this paper is to argue that effective change management can be brought about by better understanding the significant role of knowledge during change situations. Design/methodology/approach - Within this knowledge-based context, the question of how construction project teams manage knowledge during unplanned change in the construction phase within collaborative team settings is investigated through a selected case study sample within the UK construction industry. Findings- Case study findings conclude that different forms of knowledge are created and shared between project team members during change events which is very much socially constructed and centred on tacit knowledge and experience of project personnel. Originality/value- Building on the case study findings the paper finally offers a model that represents the role of knowledge during managing project change.

The cognitive neurochemistry of nicotine

The rational for this review is to provide a coherent formulation of the cognitive neurochemistry of nicotine, with the aim of suggesting research and clinical applications. The first part is a comprehensive review of the empirical studies of the enhancing effects of nicotine on information processing, especially those on attentional and mnemonic processing. Then, these studies are put in the context of recent studies on the neurochemistry of nicotine and cholinergic drugs, in general. They suggest a positive effect of nicotine on processes acting on encoded material during the post acquisition phase, the process of consolidation. Thus, the involvement of nicotinic receptors in mnemonic processing is modulation of the excitability of neurons in the hippocampal formation to enable associative processing.

Methylxanthines are the psycho-pharmacologically active constituents of chocolate

Rationale: Liking, cravings and addiction for chocolate ("chocoholism") are often explained through the presence of pharmacologically active compounds. However, mere "presence" does not guarantee psycho-activity. Objectives: Two double-blind, placebo-controlled studies measured the effects on cognitive performance and mood of the amounts of cocoa powder and methylxanthines found in a 50 g bar of dark chocolate. Methods: In study 1, participants (n=20) completed a test battery once before and twice after treatment administration. Treatments included 11.6 g cocoa powder and a caffeine and theobromine combination (19 and 250 mg, respectively). Study 2 (n=22) comprised three post-treatment test batteries and investigated the effects of "milk" and "dark" chocolate levels of these methylxanthines. The test battery consisted of a long duration simple reaction time task, a rapid visual information processing task, and a mood questionnaire. Results: Identical improvements on the mood construct "energetic arousal" and cognitive function were found for cocoa powder and the caffeine+theobromine combination versus placebo. In chocolate, both "milk chocolate" and "dark chocolate" methylxanthine doses improved cognitive function compared with "white chocolate". The effects of white chocolate did not differ significantly from those of water. Conclusion: A normal portion of chocolate exhibits psychopharmacological activity. The identical profile of effects exerted by cocoa powder and its methylxanthine constituents shows this activity to be confined to the combination of caffeine and theobromine. Methylxanthines may contribute to the popularity of chocolate; however, other attributes are probably much more important in determining chocolate's special appeal and in explaining related self-reports of chocolate cravings and "chocoholism".

The development of anxiety disorders in childhood: an integrative review

We present an integrative review of the development of child anxiety, drawing on a number of strands of research. Family aggregation and genetic studies indicate raised vulnerability to anxiety in offspring of adults with the disorder (e.g. the temperamental style of behavioural inhibition, or information processing biases). Environmental factors are also important; these include adverse life events and exposure to negative information or modelling. Parents are likely to be key, although not unique, sources of such influences, particularly if they are anxious themselves. Some parenting behaviours associated with child anxiety, such as overprotection, may be elicited by child characteristics, especially in the context of parental anxiety, and these may serve to maintain child disorder. Emerging evidence emphasizes the importance of taking the nature of child and parental anxiety into account, of constructing assessments and interventions that are both disorder specific, and of considering bidirectional influences.

Positive schizotypy and trauma-related intrusions

The current study extends previous investigation of schizotypy as a vulnerability factor for trauma-related intrusions through the use of a clinical sample. Fifty people seeking psychological interventions after experiencing a distressing or traumatic event completed measures of positive schizotypy, posttraumatic stress disorder symptomatology, peritraumatic dissociation, and mood. Individuals scoring high in positive schizotypy were vulnerable to experiencing more frequent trauma-related intrusions along with wider posttraumatic stress disorder symptomatology, including hypervigilance, avoidance, and low mood. Results are discussed within a theoretical context, suggesting that certain information processing styles associated with high schizotype individuals may account for a vulnerability to trauma-related intrusions.