An analysis of the spatial and temporal patterns of highly pathogenic avian influenza occurrence in Vietnam using national surveillance data

The objectives of this study were to describe the spatio-temporal pattern of an epidemic of highly pathogenic avian influenza (HPAI) in Vietnam and to identify potential risk factors for the introduction and maintenance of infection within the poultry population. The results indicate that during the time period 2004–early 2006 a sequence of three epidemic waves occurred in Vietnam as distinct spatial and temporal clusters. The risk of outbreak occurrence increased with a greater percentage of rice paddy fields, increasing domestic water bird and chicken density. It increased with reducing distance to higher population density aggregations, and in the third epidemic wave with increasing percentage of aquaculture. The findings indicate that agri-livestock farming systems involving domestic water birds and rice production in river delta areas are important for the maintenance and spread of infection. While the government’s control measures appear to have been effective in the South and Central parts of Vietnam, it is likely that in the North of Vietnam the vaccination campaign led to transmission of infection which was subsequently brought under control.

Colonization history of the Swiss Rhine basin by the bullhead (Cottus gobio): inference under a Bayesian spatially explicit framework

The present distribution of freshwater fish in the Alpine region has been strongly affected by colonization events occurring after the last glacial maximum (LGM), some 20,000 years ago. We use here a spatially explicit simulation framework to model and better understand their colonization dynamics in the Swiss Rhine basin. This approach is applied to the European bullhead (Cottus gobio), which is an ideal model organism to study fish past demographic processes since it has not been managed by humans. The molecular diversity of eight sampled populations is simulated and compared to observed data at six microsatellite loci under an approximate Bayesian computation framework to estimate the parameters of the colonization process. Our demographic estimates fit well with current knowledge about the biology of this species, but they suggest that the Swiss Rhine basin was colonized very recently, after the Younger Dryas some 6600 years ago. We discuss the implication of this result, as well as the strengths and limits of the spatially explicit approach coupled to the approximate Bayesian computation framework.

Linking physiology with behaviour: Functional specialisation of the visual field is reflected in gaze patterns during visual search

Based on neurophysiological findings and a grid to score binocular visual field function, two hypotheses concerning the spatial distribution of fixations during visual search were tested and confirmed in healthy participants and patients with homonymous visual field defects. Both groups showed significant biases of fixations and viewing time towards the centre of the screen and the upper screen half. Patients displayed a third bias towards the side of their field defect, which represents oculomotor compensation. Moreover, significant correlations between the extent of these three biases and search performance were found. Our findings suggest a new, more dynamic view of how functional specialisation of the visual field influences behaviour.

Neglect-like visual exploration behaviour after theta burst transcranial magnetic stimulation of the right posterior parietal cortex

The right posterior parietal cortex (PPC) is critically involved in visual exploration behaviour, and damage to this area may lead to neglect of the left hemispace. We investigated whether neglect-like visual exploration behaviour could be induced in healthy subjects using theta burst repetitive transcranial magnetic stimulation (rTMS). To this end, one continuous train of theta burst rTMS was applied over the right PPC in 12 healthy subjects prior to a visual exploration task where colour photographs of real-life scenes were presented on a computer screen. In a control experiment, stimulation was also applied over the vertex. Eye movements were measured, and the distribution of visual fixations in the left and right halves of the screen was analysed. In comparison to the performance of 28 control subjects without stimulation, theta burst rTMS over the right PPC, but not the vertex, significantly decreased cumulative fixation duration in the left screen-half and significantly increased cumulative fixation duration in the right screen-half for a time period of 30 min. These results suggest that theta burst rTMS is a reliable method of inducing transient neglect-like visual exploration behaviour.

Visual and spectral analysis of sleep EEG in acute hemispheric stroke

BACKGROUND: Reports on the effects of focal hemispheric damage on sleep EEG are rare and contradictory. PATIENTS AND METHODS: Twenty patients (mean age +/- SD 53 +/- 14 years) with a first acute hemispheric stroke and no sleep apnea were studied. Stroke severity [National Institute of Health Stroke Scale (NIHSS)], volume (diffusion-weighted brain MRI), and short-term outcome (Rankin score) were assessed. Within the first 8 days after stroke onset, 1-3 sleep EEG recordings per patient were performed. Sleep scoring and spectral analysis were based on the central derivation of the healthy hemisphere. Data were compared with those of 10 age-matched and gender-matched hospitalized controls with no brain damage and no sleep apnea. RESULTS: Stroke patients had higher amounts of wakefulness after sleep onset (112 +/- 53 min vs. 60 +/- 38 min, p < 0.05) and a lower sleep efficiency (76 +/- 10% vs. 86 +/- 8%, p < 0.05) than controls. Time spent in slow-wave sleep (SWS) and rapid eye movement (REM) sleep and total sleep time were lower in stroke patients, but differences were not significant. A positive correlation was found between the amount of SWS and stroke volume (r = 0.79). The slow-wave activity (SWA) ratio NREM sleep/wakefulness was lower in patients than in controls (p < 0.05), and correlated with NIHSS (r = -0.47). CONCLUSION: Acute hemispheric stroke is accompanied by alterations of sleep EEG over the healthy hemisphere that correlate with stroke volume and outcome. The increased SWA during wakefulness and SWS over the healthy hemisphere contralaterally to large strokes may reflect neuronal hypometabolism induced transhemispherically (diaschisis).

Antiplatelets versus Anticoagulants for the Treatment of Cervical Artery Dissection: Bayesian Meta-Analysis

OBJECTIVE To compare the effects of antiplatelets and anticoagulants on stroke and death in patients with acute cervical artery dissection. DESIGN Systematic review with Bayesian meta-analysis. DATA SOURCES The reviewers searched MEDLINE and EMBASE from inception to November 2012, checked reference lists, and contacted authors. STUDY SELECTION Studies were eligible if they were randomised, quasi-randomised or observational comparisons of antiplatelets and anticoagulants in patients with cervical artery dissection. DATA EXTRACTION Data were extracted by one reviewer and checked by another. Bayesian techniques were used to appropriately account for studies with scarce event data and imbalances in the size of comparison groups. DATA SYNTHESIS Thirty-seven studies (1991 patients) were included. We found no randomised trial. The primary analysis revealed a large treatment effect in favour of antiplatelets for preventing the primary composite outcome of ischaemic stroke, intracranial haemorrhage or death within the first 3 months after treatment initiation (relative risk 0.32, 95% credibility interval 0.12 to 0.63), while the degree of between-study heterogeneity was moderate (τ(2) = 0.18). In an analysis restricted to studies of higher methodological quality, the possible advantage of antiplatelets over anticoagulants was less obvious than in the main analysis (relative risk 0.73, 95% credibility interval 0.17 to 2.30). CONCLUSION In view of these results and the safety advantages, easier usage and lower cost of antiplatelets, we conclude that antiplatelets should be given precedence over anticoagulants as a first line treatment in patients with cervical artery dissection unless results of an adequately powered randomised trial suggest the opposite.

Analysis of eye and head coordination in a visual peripheral recognition task

Coordinated eye and head movements simultaneously occur to scan the visual world for relevant targets. However, measuring both eye and head movements in experiments allowing natural head movements may be challenging. This paper provides an approach to study eye-head coordination: First, we demonstra- te the capabilities and limits of the eye-head tracking system used, and compare it to other technologies. Second, a beha- vioral task is introduced to invoke eye-head coordination. Third, a method is introduced to reconstruct signal loss in video- based oculography caused by cornea reflection artifacts in order to extend the tracking range. Finally, parameters of eye- head coordination are identified using EHCA (eye-head co- ordination analyzer), a MATLAB software which was developed to analyze eye-head shifts. To demonstrate the capabilities of the approach, a study with 11 healthy subjects was performed to investigate motion behavior. The approach presented here is discussed as an instrument to explore eye-head coordination, which may lead to further insights into attentional and motor symptoms of certain neurological or psychiatric diseases, e.g., schizophrenia.

Visual exploration behaviour during clock reading in Alzheimer's disease

Eye movement behaviour during visual exploration of 24 patients with probable Alzheimer's disease and 24 age-matched controls was compared in a clock reading task. Controls were found to focus exploration on distinct areas at the end of each clock hand. The sum of these two areas of highest fixation density was defined as the informative region of interest (ROI). In Alzheimer's disease patients, visual exploration was less focused, with fewer fixations inside the ROI, and the time until the first fixation was inside the ROI was significantly delayed. Changes of fixation distribution correlated significantly with the ability to read the clock correctly, but did not correlate with dementia severity. In Alzheimer's disease patients, fixations were longer and saccade amplitudes were smaller. The altered visual exploration in Alzheimer's disease might be related to parietal dysfunction or to an imbalance between a degraded occipito-parietal and relatively preserved occipito-temporal visual network.

Fractionated stereotactic radiotherapy with static field conformal and non coplanar arcs for pediatric patients with craniopharyngioma: analysis of long term visual outcome and endocrine toxicity

We assessed the efficacy and the toxicity for pediatric craniopharyngioma patients of fractionated stereotactic radiotherapy (FSRT). Between May 2000 and May 2009, 9 patients (male to female ratio, 5:4) with craniopharyngiomas underwent FSRT (median dose, 54 Gy). Among the 9 patients, 6 received radiation therapy (RT) for recurrent tumors and 3 for residual disease as adjuvant therapy after incomplete surgery. Median tumor 3 volume was 2.3 cm (range, 0.1-5.8). The median target coverage was 93.7% (range 79.3-99.8%). The median conformity index was 0.94 (range, 0.6-1.4). Dose to the hippocampal region was assessed for all patients. After a median follow-up of 62.5 months (range, 32-127)the treated volume decreased in size in four of eight patients (50%). One patient was lost to follow-up. Local control and survival rates at 3 years were 100% and there were no marginal relapses. One patient, with a chronic bilateral papillary oedema after surgery, visual defect deteriorated after FSRT to a complete hemianopsia. One male patient with normal pituitary function before FSRT presented with precocious puberty at the age of 7.4 years, 24 months after FSRT. Four patients (50%) were severely obese at their last visit. FSRT is a safe treatment option for craniopharyngioma after incomplete resection.

Effects of anxiety on decision making and visual search behaviour in complex sport situations

Introduction Current empirical findings indicate that the efficiency of decision making (both for experts and near-experts) in simple situations is reduced under increased stress (Wilson, 2008). Explaining the phenomenon, the Attentional Control Theory (ACT, Eysenck et al., 2007) postulates an impairment of attentional processes resulting in a less efficient processing of visual information. From a practitioner’s perspective, it would be highly relevant to know whether this phenomenon can also be found in complex sport situations like in the game of football. Consequently, in the present study, decision making of football players was examined under regular vs. increased anxiety conditions. Methods 22 participants (11 experts and 11 near-experts) viewed 24 complex football situations (counterbalanced) in two anxiety conditions from the perspective of the last defender. They had to decide as fast and accurate as possible on the next action of the player in possession (options: shot on goal, dribble or pass to a designated team member) for equal numbers of trials in a near and far distance condition (based on the position of the player in possession). Anxiety was manipulated via a competitive environment, false feedback as well as ego threats. Decision time and accuracy, gaze behaviour (e.g., fixation duration on different locations) as well as state anxiety and mental effort were used as dependent variables and analysed with 2 (expertise) x 2 (distance) x 2 (anxiety) ANOVAs with repeated measures on the last two factors. Besides expertise differences, it was hypothesised that, based on ACT, increased anxiety reduces performance efficiency and impairs gaze behaviour. Results and Discussion Anxiety was manipulated successfully, indicated by higher ratings of state anxiety, F(1, 20) = 13.13, p < .01, ηp2 = .40. Besides expertise differences in decision making – experts responded faster, F(1, 20) = 11.32, p < .01, ηp2 = .36, and more accurate, F(1,20) = 23.93, p < .01, ηp2 = .55, than near-experts – decision time, F(1, 20) = 9.29, p < .01, ηp2 = .32, and mental effort, F(1, 20) = 7.33, p = .01, ηp2 = .27, increased for both groups in the high anxiety condition. This result confirms the ACT assumption that processing efficiency is reduced when being anxious. Replicating earlier findings, a significant expertise by distance interaction could be observed, F(1, 18) = 18.53, p < .01, ηp2 = .51), with experts fixating longer on the player in possession or the ball in the near distance and longer on other opponents, teammates and free space in the far distance condition. This shows that experts are able to adjust their gaze behaviour to affordances of displayed playing patterns. Additionally, a three way interaction was found, F(1, 18) = 7.37 p = .01, ηp2 = .29, revealing that experts utilised a reduced number of fixations in the far distance condition when being anxious indicating a reduced ability to pick up visual information. Since especially the visual search behaviour of experts was impaired, the ACT prediction that particularly top-down processes are affected by anxiety could be confirmed. Taken together, the results show that sports performance is negatively influenced by anxiety since longer response times, higher mental effort and inefficient visual search behaviour were observed. From a practitioner’s perspective, this finding might suggest preferring (implicit) perceptual cognitive training; however, this recommendation needs to be empirically supported in intervention studies. References: Eysenck, M. W., Derakshan, N., Santos, R., & Calvo, M. G. (2007). Anxiety and cognitive performance: Attentional control theory. Emotion, 7, 336-353. Wilson, M. (2008). From processing efficiency to attentional control: A mechanistic account of the anxiety-performance relationship. Int. Review of Sport and Exercise Psychology, 1, 184-201.

Effects of anxiety on decision making and visual search behaviour in complex sport situations

Based on the Attentional Control Theory (ACT; Eysenck et al., 2007), performance efficiency is decreased in high-anxiety situations because worrying thoughts compete for attentional resources. A repeated-measures design (high/low state anxiety and high/low perceptual task demands) was used to test ACT explanations. Complex football situations were displayed to expert and non-expert football players in a decision making task in a controlled laboratory setting. Ratings of state anxiety and pupil diameter measures were used to check anxiety manipulations. Dependent variables were verbal response time and accuracy, mental effort ratings and visual search behavior (e.g., visual search rate). Results confirmed that an anxiety increase, indicated by higher state-anxiety ratings and larger pupil diameters, reduced processing efficiency for both groups (higher response times and mental effort ratings). Moreover, high task demands reduced the ability to shift attention between different locations for the expert group in the high anxiety condition only. Since particularly experts, who were expected to use more top-down strategies to guide visual attention under high perceptual task demands, showed less attentional shifts in the high compared to the low anxiety condition, as predicted by ACT, anxiety seems to impair the shifting function by interrupting the balance between top-down and bottom-up processes.

Effects of anxiety on decision making and visual search Behaviour in dynamic, time-constrained situations

Einleitung Aktuelle empirische Befunde deuten darauf hin, dass Sportler/innen durch Stress und erhöhte Angst eine reduzierte Effizienz bei der Entscheidungsfindung aufweisen (Wilson, 2008). Erklärt werden kann dieser Befund durch die Attentional-Control-Theory (ACT, Eysenck et al., 2007), die postuliert, dass aufmerksamkeitslenkende Prozesse unter Angst gestört werden. Um diese Annahme für komplexe Situationen im Sport zu prüfen, wurden Fußballspieler unter erhöhten und regulären Druckbedingungen verglichen. Methode Je 11 Experten und Nicht-Experten hatten aus der Perspektive des Abwehrspielers die Aufgabe, in zwei mal 24 Spielsituationen so schnell und korrekt wie möglich verbal anzugeben, welche Aktion der ballführende Spieler (in naher vs. ferner Spielsituation) nach Ausblendung der Szene ausführen wird. Während im ersten Block der Druck nicht erhöht wurde, wurden Druckbedingungen im zweiten Block u.a. durch eine Wettkampfsituation und „falscher“ Ergebnisrückmeldung gesteigert. Entscheidungs- und Blickverhalten (u.a. Anzahl Fixationen), Pupillengröße, Zustandsangst und „Mental Effort“ (Wilson, 2008) wurden erfasst. Neben Expertiseunterschieden wurde erwartet, dass erhöhte Angst die Entscheidungseffizienz sowie das Blickverhalten stört (ACT-Annahme), was mit 2 (Experten/Nicht-Experten) x 2 (nahe/ferne Spielsituation) x 2 (hohe/reguläre Druckbedingung) ANOVAs (? = .05) mit Messwiederholungen auf den letzten beiden Faktoren geprüft wurde. Ergebnisse Druckmanipulationen führten zu höherer Zustandsangst und größeren Pupillendurchmessern. Neben Expertiseunterschieden – Experten antworteten schneller, korrekter und zeigten ein situationsangepasstes visuelles Suchverhalten – wiesen beide Gruppen in Drucksituationen längere Antwortzeiten und höheren Mental Effort auf. Erhöhter Druck führte bei Experten zur Reduktion der Fixationsortwechsel für ferne Spielsituationen. Nicht-Experten differenzierten ihr Suchverhalten weder zwischen Bedingungen noch für Spielsituationen. Diskussion Die Resultate bestätigen die ACT-Annahme, dass Angst und Stress die sportliche Leistung durch längere Reaktionszeiten, höhere kognitive Anstrengung und ein teilweise ineffizientes visuelles Suchverhalten negativ beeinflusst. Eine gestörte Balance zwischen Top-Down und Bottom-Up-Prozessen könnte die Ursache sein (Eysenck et al., 2007). Literatur Eysenck, M. W., Derakshan, N., Santos, R., & Calvo, M. G. (2007). Anxiety and cognitive performance: Attentional control theory. Emotion, 7, 336–353. Wilson, M. (2008). From processing efficiency to attentional control: A mechanistic account of the anxiety-performance relationship. International Review of Sport and Exercise Psychology, 1, 184– 201. 2 Vorträge und Poster