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Sample records for spatial alternation task

  1. Effect of methylphenidate on enhancement of spatial learning by novel alternated dual task.

    Science.gov (United States)

    Veetil, Praveen Kottath; Mukkadan, Joseph Kurian

    2011-01-01

    The novel alternated dual task (ADT) arranged rats to learn T-maze spontaneous alternation task and radial arm maze (RAM) task alternatively, and by doing ADT, rats could acquire the tasks more easily than non alternated dual task (NADT) group. Also retention capacity of ADT group was significantly more and ADT help to learn a complex task faster than learning it in isolation from other tasks. In the present study effect of methylphenidate (MPD), a mood elevator, known to enhance learning and memory, on ADT procedure is assessed. Also effect of ADT procedure and MPD on spatial learning and memory are compared. Different groups were assigned by administering MPD (intraperitoneal injection at a dose of 3 mg/kg body weight) during different phases of behavioural experiments, and control groups received saline injection. MPD administration increased both acquisition and retention capacities. The amelioration attained for retention of complex task by ADT procedure, could be achieved by NADT rats only by administration of MPD. The influence of ADT procedure on acquisition and retention of TM and RAM tasks were similar to the effects of MPD, especially for the RAM task. MPD at low dose is found to enhance the learning and memory capacity in rats, than deteriorating it, supporting the use of MPD as a drug to treat attention deficit hyperactive disorder. The recent reports suggesting the effect of MPD only on retention and not on acquisition could not be confirmed, as enhancement for both acquisition and retention was found in this study.

  2. Rule knowledge aids performance on spatial and object alternation tasks by alcoholic patients with and without Korsakoff’s amnesia

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    Fiona J Bardenhagen

    2007-01-01

    Full Text Available Fiona J Bardenhagen1,2, Marlene Oscar-Berman3, Stephen C Bowden2,41School of Psychology, Victoria University, Melbourne, Victoria, Australia; 2Clinical Neurosciences, St. Vincent’s Hospital, Melbourne, Australia; 3Division of Psychiatry and Departments of Neurology and Anatomy and Neurobiology, Boston University School of Medicine; and Psychology Research Service, US Department of Veterans Affairs (VA Healthcare System, Jamaica Plain Campus, MA, USA; 4School of Behavioural Science, University of Melbourne, Parkville, Victoria, AustraliaAbstract: Delayed alternation (DA and object alternation (OA tasks traditionally have been used to measure defective response inhibition associated with dysfunction of frontal brain systems. However, these tasks are also sensitive to nonfrontal lesions, and cognitive processes such as the induction of rule-learning strategies also are needed in order to perform well on these tasks. Performance on DA and OA tasks was explored in 10 patients with alcohol-induced persisting amnestic disorder (Korsakoff’s syndrome, 11 abstinent long-term alcoholics, and 13 healthy non-alcoholic controls under each of two rule provision conditions: Alternation Rule and Correction Rule. Results confirmed that rule knowledge is a crucial cognitive component for solving problems such as DA and OA, and therefore, that errors on these tasks are not due to defective response inhibition alone. Further, rule-induction strategies were helpful to Korsakoff patients, despite their poorer performance on the tasks. These results stress the role of multiple cognitive abilities in successful performance on rule induction tasks. Evidence that these cognitive abilities are served by diffusely distributed neural networks should be considered when interpreting behavioral impairments on these tasks.Keywords: alcoholism, Korsakoff’s syndrome, comparative neuropsychology, perseveration, rule induction, working memory

  3. Efficient task assignment in spatial crowdsourcing with worker and task privacy protection

    KAUST Repository

    Liu, An; Wang, Weiqi; Shang, Shuo; Li, Qing; Zhang, Xiangliang

    2017-01-01

    Spatial crowdsourcing (SC) outsources tasks to a set of workers who are required to physically move to specified locations and accomplish tasks. Recently, it is emerging as a promising tool for emergency management, as it enables efficient and cost

  4. Selection of spatial reference frames depends on task's demands

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    Greeshma Sharma

    2016-12-01

    Full Text Available Spatial reference frames (SRF are the means of representing spatial relations or locations either in an egocentric coordinate system (centred on navigator or in an allocentric coordinate system (Centred on object. It is necessary to understand when and how spatial representation switches between allocentric and egocentric reference frames in context to spatial tasks. The objective of this study was to explore if the elementary spatial representation does exist, whether it would remain consistent or change under the influence of a task's demand. Also, we explored how the SRF would assist if the environment is enriched with landmarks, having multiple routes for wayfinding. The results showed that the switching of SRF depends not only on the default representation but also on a task's demand. They also demonstrated that participants who were using allocentric representation performed better in the presence of landmarks.

  5. Estimating demand for alternatives to cigarettes with online purchase tasks.

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    O'Connor, Richard J; June, Kristie M; Bansal-Travers, Maansi; Rousu, Matthew C; Thrasher, James F; Hyland, Andrew; Cummings, K Michael

    2014-01-01

    To explore how advertising affects demand for cigarettes and potential substitutes, including snus, dissolvable tobacco, and medicinal nicotine. A Web-based experiment randomized 1062 smokers to see advertisements for alternative nicotine products or soft drinks, then complete a series of purchase tasks, which were used to estimate demand elasticity, peak consumption, and cross-price elasticity (CPE) for tobacco products. Lower demand elasticity and greater peak consumption were seen for cigarettes compared to all alternative products (p demand. These findings suggest significantly lower demand for alternative nicotine sources among smokers than previously revealed.

  6. Spatial Programming for Industrial Robots Through Task Demonstration

    OpenAIRE

    Jens Lambrecht; Martin Kleinsorge; Martin Rosenstrauch; Jörg Krüger

    2013-01-01

    Abstract We present an intuitive system for the programming of industrial robots using markerless gesture recognition and mobile augmented reality in terms of programming by demonstration. The approach covers gesture-based task definition and adaption by human demonstration, as well as task evaluation through augmented reality. A 3D motion tracking system and a handheld device establish the basis for the presented spatial programming system. In this publication, we present a prototype toward ...

  7. Privacy-Preserving Task Assignment in Spatial Crowdsourcing

    KAUST Repository

    Liu, An

    2017-09-20

    With the progress of mobile devices and wireless networks, spatial crowdsourcing (SC) is emerging as a promising approach for problem solving. In SC, spatial tasks are assigned to and performed by a set of human workers. To enable effective task assignment, however, both workers and task requesters are required to disclose their locations to untrusted SC systems. In this paper, we study the problem of assigning workers to tasks in a way that location privacy for both workers and task requesters is preserved. We first combine the Paillier cryptosystem with Yao’s garbled circuits to construct a secure protocol that assigns the nearest worker to a task. Considering that this protocol cannot scale to a large number of workers, we then make use of Geohash, a hierarchical spatial index to design a more efficient protocol that can securely find approximate nearest workers. We theoretically show that these two protocols are secure against semi-honest adversaries. Through extensive experiments on two real-world datasets, we demonstrate the efficiency and effectiveness of our protocols.

  8. Almeria spatial memory recognition test (ASMRT): Gender differences emerged in a new passive spatial task.

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    Tascón, Laura; García-Moreno, Luis Miguel; Cimadevilla, Jose Manuel

    2017-06-09

    Many different human spatial memory tasks were developed in the last two decades. Virtual reality based tasks make possible developing different scenarios and situations to assess spatial orientation but sometimes these tasks are complex for specific populations like children and older-adults. A new spatial task with a very limited technological requirement was developed in this study. It demanded the use of spatial memory for an accurate solution. It also proved to be sensitive to gender differences, with men outperforming women under high specific difficulty levels. Thanks to its simplicity it could be applied as a screening test and is easy to combine with EEG and fMRI studies. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Dizocilpine (MK-801) impairs learning in the active place avoidance task but has no effect on the performance during task/context alternation.

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    Vojtechova, Iveta; Petrasek, Tomas; Hatalova, Hana; Pistikova, Adela; Vales, Karel; Stuchlik, Ales

    2016-05-15

    The prevention of engram interference, pattern separation, flexibility, cognitive coordination and spatial navigation are usually studied separately at the behavioral level. Impairment in executive functions is often observed in patients suffering from schizophrenia. We have designed a protocol for assessing these functions all together as behavioral separation. This protocol is based on alternated or sequential training in two tasks testing different hippocampal functions (the Morris water maze and active place avoidance), and alternated or sequential training in two similar environments of the active place avoidance task. In Experiment 1, we tested, in adult rats, whether the performance in two different spatial tasks was affected by their order in sequential learning, or by their day-to-day alternation. In Experiment 2, rats learned to solve the active place avoidance task in two environments either alternately or sequentially. We found that rats are able to acquire both tasks and to discriminate both similar contexts without obvious problems regardless of the order or the alternation. We used two groups of rats, controls and a rat model of psychosis induced by a subchronic intraperitoneal application of 0.08mg/kg of dizocilpine (MK-801), a non-competitive antagonist of NMDA receptors. Dizocilpine had no selective effect on parallel/sequential learning of tasks/contexts. However, it caused hyperlocomotion and a significant deficit in learning in the active place avoidance task regardless of the task alternation. Cognitive coordination tested by this task is probably more sensitive to dizocilpine than spatial orientation because no hyperactivity or learning impairment was observed in the Morris water maze. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Spatial memory tasks in rodents: what do they model?

    Science.gov (United States)

    Morellini, Fabio

    2013-10-01

    The analysis of spatial learning and memory in rodents is commonly used to investigate the mechanisms underlying certain forms of human cognition and to model their dysfunction in neuropsychiatric and neurodegenerative diseases. Proper interpretation of rodent behavior in terms of spatial memory and as a model of human cognitive functions is only possible if various navigation strategies and factors controlling the performance of the animal in a spatial task are taken into consideration. The aim of this review is to describe the experimental approaches that are being used for the study of spatial memory in rats and mice and the way that they can be interpreted in terms of general memory functions. After an introduction to the classification of memory into various categories and respective underlying neuroanatomical substrates, I explain the concept of spatial memory and its measurement in rats and mice by analysis of their navigation strategies. Subsequently, I describe the most common paradigms for spatial memory assessment with specific focus on methodological issues relevant for the correct interpretation of the results in terms of cognitive function. Finally, I present recent advances in the use of spatial memory tasks to investigate episodic-like memory in mice.

  11. Comparison of congruence judgment and auditory localization tasks for assessing the spatial limits of visual capture.

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    Bosen, Adam K; Fleming, Justin T; Brown, Sarah E; Allen, Paul D; O'Neill, William E; Paige, Gary D

    2016-12-01

    Vision typically has better spatial accuracy and precision than audition and as a result often captures auditory spatial perception when visual and auditory cues are presented together. One determinant of visual capture is the amount of spatial disparity between auditory and visual cues: when disparity is small, visual capture is likely to occur, and when disparity is large, visual capture is unlikely. Previous experiments have used two methods to probe how visual capture varies with spatial disparity. First, congruence judgment assesses perceived unity between cues by having subjects report whether or not auditory and visual targets came from the same location. Second, auditory localization assesses the graded influence of vision on auditory spatial perception by having subjects point to the remembered location of an auditory target presented with a visual target. Previous research has shown that when both tasks are performed concurrently they produce similar measures of visual capture, but this may not hold when tasks are performed independently. Here, subjects alternated between tasks independently across three sessions. A Bayesian inference model of visual capture was used to estimate perceptual parameters for each session, which were compared across tasks. Results demonstrated that the range of audiovisual disparities over which visual capture was likely to occur was narrower in auditory localization than in congruence judgment, which the model indicates was caused by subjects adjusting their prior expectation that targets originated from the same location in a task-dependent manner.

  12. Comparison of Congruence Judgment and Auditory Localization Tasks for Assessing the Spatial Limits of Visual Capture

    Science.gov (United States)

    Bosen, Adam K.; Fleming, Justin T.; Brown, Sarah E.; Allen, Paul D.; O'Neill, William E.; Paige, Gary D.

    2016-01-01

    Vision typically has better spatial accuracy and precision than audition, and as a result often captures auditory spatial perception when visual and auditory cues are presented together. One determinant of visual capture is the amount of spatial disparity between auditory and visual cues: when disparity is small visual capture is likely to occur, and when disparity is large visual capture is unlikely. Previous experiments have used two methods to probe how visual capture varies with spatial disparity. First, congruence judgment assesses perceived unity between cues by having subjects report whether or not auditory and visual targets came from the same location. Second, auditory localization assesses the graded influence of vision on auditory spatial perception by having subjects point to the remembered location of an auditory target presented with a visual target. Previous research has shown that when both tasks are performed concurrently they produce similar measures of visual capture, but this may not hold when tasks are performed independently. Here, subjects alternated between tasks independently across three sessions. A Bayesian inference model of visual capture was used to estimate perceptual parameters for each session, which were compared across tasks. Results demonstrated that the range of audio-visual disparities over which visual capture was likely to occur were narrower in auditory localization than in congruence judgment, which the model indicates was caused by subjects adjusting their prior expectation that targets originated from the same location in a task-dependent manner. PMID:27815630

  13. Interference between postural control and spatial vs. non-spatial auditory reaction time tasks in older adults.

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    Fuhrman, Susan I; Redfern, Mark S; Jennings, J Richard; Furman, Joseph M

    2015-01-01

    This study investigated whether spatial aspects of an information processing task influence dual-task interference. Two groups (Older/Young) of healthy adults participated in dual-task experiments. Two auditory information processing tasks included a frequency discrimination choice reaction time task (non-spatial task) and a lateralization choice reaction time task (spatial task). Postural tasks included combinations of standing with eyes open or eyes closed on either a fixed floor or a sway-referenced floor. Reaction times and postural sway via center of pressure were recorded. Baseline measures of reaction time and sway were subtracted from the corresponding dual-task results to calculate reaction time task costs and postural task costs. Reaction time task cost increased with eye closure (p = 0.01), sway-referenced flooring (p vision x age interaction indicated that older subjects had a significant vision X task interaction whereas young subjects did not. However, when analyzed by age group, the young group showed minimal differences in interference for the spatial and non-spatial tasks with eyes open, but showed increased interference on the spatial relative to non-spatial task with eyes closed. On the contrary, older subjects demonstrated increased interference on the spatial relative to the non-spatial task with eyes open, but not with eyes closed. These findings suggest that visual-spatial interference may occur in older subjects when vision is used to maintain posture.

  14. Electrocorticographic language mapping with a listening task consisting of alternating speech and music phrases.

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    Mooij, Anne H; Huiskamp, Geertjan J M; Gosselaar, Peter H; Ferrier, Cyrille H

    2016-02-01

    Electrocorticographic (ECoG) mapping of high gamma activity induced by language tasks has been proposed as a more patient friendly alternative for electrocortical stimulation mapping (ESM), the gold standard in pre-surgical language mapping of epilepsy patients. However, ECoG mapping often reveals more language areas than considered critical with ESM. We investigated if critical language areas can be identified with a listening task consisting of speech and music phrases. Nine patients with implanted subdural grid electrodes listened to an audio fragment in which music and speech alternated. We analysed ECoG power in the 65-95 Hz band and obtained task-related activity patterns in electrodes over language areas. We compared the spatial distribution of sites that discriminated between listening to speech and music to ESM results using sensitivity and specificity calculations. Our listening task of alternating speech and music phrases had a low sensitivity (0.32) but a high specificity (0.95). The high specificity indicates that this test does indeed point to areas that are critical to language processing. Our test cannot replace ESM, but this short and simple task can give a reliable indication where to find critical language areas, better than ECoG mapping using language tasks alone. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  15. The role of physical content in piagetian spatial tasks: Sex differences in spatial knowledge?

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    Golbeck, Susan L.

    Sex-related differences on Piagetian horizontality (water level) and verticality (plumb line) tasks were examined in 64 college students. It was hypothesized that females' difficulties on these Euclidean spatial problems are due not to differences in underlying spatial competence, but rather to differences in knowledge of task specific information about the physical properties of water levels and plumb lines. This was tested by presenting subjects with the standard water level and plumb line problems and also modified problems not requiring knowledge of physical principles (i.e., drawing straight up and down or straight across lines inside tipped rectangles). While males were expected to outperform females on the standard tasks, no sex differences were expected on the modified tasks. Results of an ANOVA on scores for horizontality and verticality each showed main effects for sex and task version but failed to reveal the hypothesized interaction. However, performance on the Euclidean spatial tasks was also considered in terms of overall success versus failure. While males were more successful than females in the standard format, males and females were equally successful in the modified, nonphysical, format. Hence, college aged males and females generally do not differ in spatial competence although they may be differentially influenced by task content. Findings are discussed in terms of their implications for theory and practice. It is emphasized that science educators must be especially aware of such task influences for females so that performance deficits are not mistaken for competence deficits.

  16. Attentional reorienting triggers spatial asymmetries in a search task with cross-modal spatial cueing.

    Directory of Open Access Journals (Sweden)

    Rebecca E Paladini

    Full Text Available Cross-modal spatial cueing can affect performance in a visual search task. For example, search performance improves if a visual target and an auditory cue originate from the same spatial location, and it deteriorates if they originate from different locations. Moreover, it has recently been postulated that multisensory settings, i.e., experimental settings, in which critical stimuli are concurrently presented in different sensory modalities (e.g., visual and auditory, may trigger asymmetries in visuospatial attention. Thereby, a facilitation has been observed for visual stimuli presented in the right compared to the left visual space. However, it remains unclear whether auditory cueing of attention differentially affects search performance in the left and the right hemifields in audio-visual search tasks. The present study investigated whether spatial asymmetries would occur in a search task with cross-modal spatial cueing. Participants completed a visual search task that contained no auditory cues (i.e., unimodal visual condition, spatially congruent, spatially incongruent, and spatially non-informative auditory cues. To further assess participants' accuracy in localising the auditory cues, a unimodal auditory spatial localisation task was also administered. The results demonstrated no left/right asymmetries in the unimodal visual search condition. Both an additional incongruent, as well as a spatially non-informative, auditory cue resulted in lateral asymmetries. Thereby, search times were increased for targets presented in the left compared to the right hemifield. No such spatial asymmetry was observed in the congruent condition. However, participants' performance in the congruent condition was modulated by their tone localisation accuracy. The findings of the present study demonstrate that spatial asymmetries in multisensory processing depend on the validity of the cross-modal cues, and occur under specific attentional conditions, i.e., when

  17. Privacy-Preserving Task Assignment in Spatial Crowdsourcing

    KAUST Repository

    Liu, An; Li, Zhi-Xu; Liu, Guan-Feng; Zheng, Kai; Zhang, Min; Li, Qing; Zhang, Xiangliang

    2017-01-01

    untrusted SC systems. In this paper, we study the problem of assigning workers to tasks in a way that location privacy for both workers and task requesters is preserved. We first combine the Paillier cryptosystem with Yao’s garbled circuits to construct a secure protocol that assigns the nearest worker to a task. Considering that this protocol cannot scale to a large number of workers, we then make use of Geohash, a hierarchical spatial index to design a more efficient protocol that can securely find approximate nearest workers. We theoretically show that these two protocols are secure against semi-honest adversaries. Through extensive experiments on two real-world datasets, we demonstrate the efficiency and effectiveness of our protocols.

  18. Spatial Programming for Industrial Robots through Task Demonstration

    Directory of Open Access Journals (Sweden)

    Jens Lambrecht

    2013-05-01

    Full Text Available Abstract We present an intuitive system for the programming of industrial robots using markerless gesture recognition and mobile augmented reality in terms of programming by demonstration. The approach covers gesture-based task definition and adaption by human demonstration, as well as task evaluation through augmented reality. A 3D motion tracking system and a handheld device establish the basis for the presented spatial programming system. In this publication, we present a prototype toward the programming of an assembly sequence consisting of several pick-and-place tasks. A scene reconstruction provides pose estimation of known objects with the help of the 2D camera of the handheld. Therefore, the programmer is able to define the program through natural bare-hand manipulation of these objects with the help of direct visual feedback in the augmented reality application. The program can be adapted by gestures and transmitted subsequently to an arbitrary industrial robot controller using a unified interface. Finally, we discuss an application of the presented spatial programming approach toward robot-based welding tasks.

  19. Sex differences in spatial memory using serial and search tasks.

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    Shah, Darshna S; Prados, Jose; Gamble, Jasmin; De Lillo, Carlo; Gibson, Claire L

    2013-11-15

    The present study assessed the spatial abilities of male and female human participants using different versions of the non-navigational Corsi block-tapping test (CBT) and a search task. Males performed significantly better than females on the standard manual version of the CBT; however, the standard CBT does not allow discrimination between spatial memory span and the role of spatial organisational factors (structure, path length and presence of crossings) in the sequences to recall. These organisational factors were assessed, therefore, in an experiment in which 7-block-sequences had to be recalled in a computerised version of the CBT. No sex differences in performance were observed on the computerised CBT, indicating that males do not make better use of spatial organisational principles. Accordingly, sex differences observed in the manual CBT are likely to rely upon differences in memory span between males and females. In the search task, participants could locate a goal by reference to a Euclidian space (the geometry of a virtual enclose) or to proximal non-geometric cues. Both male and female participants showed a preference for the non-geometric cues, which overshadowed learning about the geometric cues when the two sets were available simultaneously during the training stage. These results indicate that sex differences do exist in those tests which are dependent on memory span. Sex differences were absent, however, in spatial organisational skills or in the usage of Euclidian and egocentric strategies to solve problems relying on spatial ability. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Aging Effect on Audiovisual Integrative Processing in Spatial Discrimination Task

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    Zhi Zou

    2017-11-01

    Full Text Available Multisensory integration is an essential process that people employ daily, from conversing in social gatherings to navigating the nearby environment. The aim of this study was to investigate the impact of aging on modulating multisensory integrative processes using event-related potential (ERP, and the validity of the study was improved by including “noise” in the contrast conditions. Older and younger participants were involved in perceiving visual and/or auditory stimuli that contained spatial information. The participants responded by indicating the spatial direction (far vs. near and left vs. right conveyed in the stimuli using different wrist movements. electroencephalograms (EEGs were captured in each task trial, along with the accuracy and reaction time of the participants’ motor responses. Older participants showed a greater extent of behavioral improvements in the multisensory (as opposed to unisensory condition compared to their younger counterparts. Older participants were found to have fronto-centrally distributed super-additive P2, which was not the case for the younger participants. The P2 amplitude difference between the multisensory condition and the sum of the unisensory conditions was found to correlate significantly with performance on spatial discrimination. The results indicated that the age-related effect modulated the integrative process in the perceptual and feedback stages, particularly the evaluation of auditory stimuli. Audiovisual (AV integration may also serve a functional role during spatial-discrimination processes to compensate for the compromised attention function caused by aging.

  1. What does spatial alternation tell us about retrosplenial cortex function?

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    Andrew John Dudley Nelson

    2015-05-01

    Full Text Available The retrosplenial cortex supports navigation, but there are good reasons to suppose that the retrosplenial cortex has a very different role in spatial memory from that of the hippocampus and anterior thalamic nuclei. For example, retrosplenial lesions appear to have little or no effect on standard tests of spatial alternation. To examine these differences, the current study sought to determine whether the retrosplenial cortex is important for just one spatial cue type (e.g. allocentric, directional or intra-maze cues or whether the retrosplenial cortex helps the animal switch between competing spatial strategies or competing cue types. Using T-maze alternation, retrosplenial lesion rats were challenged with situations in which the available spatial information between the sample and test phases was changed, so taxing the interaction between different cue types. Clear lesion deficits emerged when intra- and extra-maze cues were placed in conflict (by rotating the maze between the sample and choice phases, or when the animals were tested in the dark in a double-maze. Finally, temporary inactivation of the retrosplenial cortex by muscimol infusions resulted in a striking deficit on standard T-maze alternation, indicating that, over time, other sites may be able to compensate for the loss of the retrosplenial cortex. This pattern of results is consistent with the impoverished use of both allocentric and directional information, exacerbated by an impaired ability to switch between different cue types.

  2. Efficient task assignment in spatial crowdsourcing with worker and task privacy protection

    KAUST Repository

    Liu, An

    2017-08-01

    Spatial crowdsourcing (SC) outsources tasks to a set of workers who are required to physically move to specified locations and accomplish tasks. Recently, it is emerging as a promising tool for emergency management, as it enables efficient and cost-effective collection of critical information in emergency such as earthquakes, when search and rescue survivors in potential ares are required. However in current SC systems, task locations and worker locations are all exposed in public without any privacy protection. SC systems if attacked thus have penitential risk of privacy leakage. In this paper, we propose a protocol for protecting the privacy for both workers and task requesters while maintaining the functionality of SC systems. The proposed protocol is built on partially homomorphic encryption schemes, and can efficiently realize complex operations required during task assignment over encrypted data through a well-designed computation strategy. We prove that the proposed protocol is privacy-preserving against semi-honest adversaries. Simulation on two real-world datasets shows that the proposed protocol is more effective than existing solutions and can achieve mutual privacy-preserving with acceptable computation and communication cost.

  3. The relationship between language and spatial ability an analysis of spatial language for reconstructing the solving of spatial tasks

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    Mizzi, Angel

    2017-01-01

    This work investigates how different fifth-grade students solve spatial-verbal tasks and the role of language in this process. Based on a synthesis of theoretical foundations and methodological issues for supporting the relationship between spatial ability and language, this present study examines and classifies strategies used by students as well as the obstacles they encounter when solving spatial tasks in the reconstruction method. Contents Theoretical Framework Design and Implementation Results and Discussion from the Inductive Data Analyses Target Groups Scholars and students of mathematics education Teachers of mathematics in primary and secondary schools About the Author Angel Mizzi works as a research assistant and lecturer at the University of Duisburg-Essen, where he has successfully completed his PhD studies in mathematics education.

  4. Comparing temporal order judgments and choice reaction time tasks as indices of exogenous spatial cuing.

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    Eskes, Gail A; Klein, Raymond M; Dove, Mary Beth; Coolican, Jamesie; Shore, David I

    2007-11-30

    Attentional disorders are common in individuals with neurological or psychiatric conditions and impact on recovery and outcome. Thus, it is critical to develop theory-based measures of attentional function to understand potential mechanisms underlying the disorder and to evaluate the effect of intervention. The present study compared two alternative methods to measure the effects of attentional cuing that could be used in populations of individuals who may not be able to make manual responses normally or may show overall slowing in responses. Spatial attention was measured with speeded and unspeeded methods using either manual or voice responses in two standard attention paradigms: the cued target discrimination reaction time (RT) paradigm and the unspeeded temporal order judgment (TOJ) task. The comparison of speeded and unspeeded tasks specifically addresses the concern about interpreting RT differences between cued and uncued trials (taken as a proxy for attention) in the context of drastically different baseline RTs. We found significant cuing effects for both tasks (speeded RT and untimed TOJ) and both response types (vocal and manual) giving clinicians and researchers alternative methods with which to measure the effects of attention in different populations who may not be able to perform the standard speeded RT task.

  5. Complex neural codes in rat prelimbic cortex are stable across days on a spatial decision task

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    Nathaniel J. Powell

    2014-04-01

    Full Text Available The rodent prelimbic cortex has been shown to play an important role in cognitive processing, and has been implicated in encoding many different parameters relevant to solving decision-making tasks. However, it is not known how the prelimbic cortex represents all these disparate variables, and if they are simultaneously represented when the task requires it. In order to investigate this question, we trained rats to run the Multiple-T Left Right Alternate (MT-LRA task and recorded multi-unit ensembles from their prelimbic regions. Significant populations of cells in the prelimbic cortex represented the strategy controlling reward receipt on a given lap, whether the animal chose to go right or left on a given lap, and whether the animal made a correct decision or an error on a given lap. These populations overlapped in the cells recorded, with several cells demonstrating differential firing to all three variables. The spatial and strategic firing patterns of individual prelimbic cells were highly conserved across several days of running this task, indicating that each cell encoded the same information across days.

  6. Hippocampal activation during the recall of remote spatial memories in radial maze tasks.

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    Schlesiger, Magdalene I; Cressey, John C; Boublil, Brittney; Koenig, Julie; Melvin, Neal R; Leutgeb, Jill K; Leutgeb, Stefan

    2013-11-01

    Temporally graded retrograde amnesia is observed in human patients with medial temporal lobe lesions as well as in animal models of medial temporal lobe lesions. A time-limited role for these structures in memory recall has also been suggested by the observation that the rodent hippocampus and entorhinal cortex are activated during the retrieval of recent but not of remote memories. One notable exception is the recall of remote memories for platform locations in the water maze, which requires an intact hippocampus and results in hippocampal activation irrespective of the age of the memory. These findings raise the question whether the hippocampus is always involved in the recall of spatial memories or, alternatively, whether it might be required for procedural computations in the water maze task, such as for calculating a path to a hidden platform. We performed spatial memory testing in radial maze tasks to distinguish between these possibilities. Radial maze tasks require a choice between spatial locations on a center platform and thus have a lesser requirement for navigation than the water maze. However, we used a behavioral design in the radial maze that retained other aspects of the standard water maze task, such as the use of multiple start locations and retention testing in a single trial. Using the immediate early gene c-fos as a marker for neuronal activation, we found that all hippocampal subregions were more activated during the recall of remote compared to recent spatial memories. In areas CA3 and CA1, activation during remote memory testing was higher than in rats that were merely reexposed to the testing environment after the same time interval. Conversely, Fos levels in the dentate gyrus were increased after retention testing to the extent that was also observed in the corresponding exposure control group. This pattern of hippocampal activation was also obtained in a second version of the task that only used a single start arm instead of multiple

  7. Solution strategies as possible explanations of individual and sex differences in a dynamic spatial task.

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    Peña, Daniel; Contreras, María José; Shih, Pei Chun; Santacreu, José

    2008-05-01

    When individuals perform spatial tasks, individual differences emerge in accuracy and speed as well as in the response patterns used to cope with the task. The purpose of this study is to identify, through empirical criteria, the different response patterns or strategies used by individuals when performing the dynamic spatial task presented in the Spatial Orientation Dynamic Test-Revised (SODT-R). Results show that participants can be classified according to their response patterns. Three different ways of solving a task are described, and their relation to (a) performance factors (response latency, response frequency, and invested time) and (b) ability tests (analytical reasoning, verbal reasoning, and spatial estimation) are investigated. Sex differences in response patterns and performance are also analyzed. It is found that the frequency with which men and women employ each one of the strategies described here, is different and statistically significant. Thus, employed strategy plays an important role when interpreting sex differences on dynamic spatial tasks.

  8. The effects of the botanical estrogen, isoliquiritigenin on delayed spatial alternation.

    Science.gov (United States)

    Kundu, Payel; Neese, Steven L; Bandara, Suren; Monaikul, Supida; Helferich, William G; Doerge, Daniel R; Khan, Ikhlas A; Schantz, Susan L

    Age-related declines in cognitive function can impair working memory, reduce speed of processing, and alter attentional resources. In particular, menopausal women may show an acceleration in the rate of cognitive decline as well as an increased vulnerability to brain diseases as estrogens may play a neuroprotective and neurotrophic role in the brain. To treat menopausal symptoms, many women turn to botanical estrogens that are promoted as a safe and natural alternative to traditional hormone replacement therapy. However, the majority of these compounds have not been systematically evaluated for efficacy and safety. The current study investigated the efficacy of the commercially available botanical estrogenic compound isoliquiritigenin (ISL) to alter performance on an operant working memory task, delayed spatial alternation (DSA). ISL is a compound found in licorice root that has been shown to have a wide range of effects on different biological systems, including estrogenic properties. This botanical is currently being used in over the counter dietary supplements. Middle-aged (12-month old) Long-Evans female rats were ovariectomized and orally dosed with either 0 mg, 6 mg, 12 mg or 24 mg of ISL 60 min before testing on the DSA task. The DSA task required the rat to alternate its responses between two retractable levers in order to earn food rewards. Random delays of 0, 3, 6, 9 or 18 s were imposed between opportunities to press. ISL treatment failed to alter DSA performance. Previous work from our research group has found that estrogenic compounds, including 17β-estradiol and the botanical estrogen genistein impair performance on the DSA task. The goal of our botanical estrogens research is to find compounds that offer some of the beneficial effects of estrogen supplementation, without the harmful effects. This work suggests that ISL may not carry the cognitive risks associated with most other estrogenic compounds tested to date. Copyright © 2018

  9. Chew on this: No support for facilitating effects of gum on spatial task performance.

    Science.gov (United States)

    Nader, Ingo W; Gittler, Georg; Waldherr, Karin; Pietschnig, Jakob

    2010-09-01

    To determine whether chewing of gum facilitates spatial task performance in healthy participants, two behavioral experiments were performed. In the first experiment, spatial task performance of 349 men and women preceding and after treatment administration (saccharated chewing gum, sugar-free chewing gum, no chewing gum) was assessed using effect modeling by means of Item Response Theory. In the second experiment, another 100 participants were either administered sugar-free chewing gum or no chewing gum during spatial task performance. Effects of gum in the second study were assessed by standard means of data analysis. Results indicated no significant effects of either chewing gum or sugar on spatial task performance in either experiment. Our findings are consistent with recent studies investigating the influences of chewing gum on various memory functions, extending them by another measure of cognitive ability. Thus, further doubt is cast on enhancing effects of chewing gum on cognitive task performance. Copyright 2010 Elsevier Ltd. All rights reserved.

  10. Spatial effects, sampling errors, and task specialization in the honey bee.

    Science.gov (United States)

    Johnson, B R

    2010-05-01

    Task allocation patterns should depend on the spatial distribution of work within the nest, variation in task demand, and the movement patterns of workers, however, relatively little research has focused on these topics. This study uses a spatially explicit agent based model to determine whether such factors alone can generate biases in task performance at the individual level in the honey bees, Apis mellifera. Specialization (bias in task performance) is shown to result from strong sampling error due to localized task demand, relatively slow moving workers relative to nest size, and strong spatial variation in task demand. To date, specialization has been primarily interpreted with the response threshold concept, which is focused on intrinsic (typically genotypic) differences between workers. Response threshold variation and sampling error due to spatial effects are not mutually exclusive, however, and this study suggests that both contribute to patterns of task bias at the individual level. While spatial effects are strong enough to explain some documented cases of specialization; they are relatively short term and not explanatory for long term cases of specialization. In general, this study suggests that the spatial layout of tasks and fluctuations in their demand must be explicitly controlled for in studies focused on identifying genotypic specialists.

  11. Interference between a fast-paced spatial puzzle task and verbal memory demands.

    Science.gov (United States)

    Epling, Samantha L; Blakely, Megan J; Russell, Paul N; Helton, William S

    2017-06-01

    Research continues to provide evidence that people are poor multi-taskers. Cognitive resource theory is a common explanation for the inability to efficiently perform multiple tasks at the same time. This theory proposes that one's limited supply of cognitive resources can be utilized faster than it is replenished, which results in a performance decline, particularly when these limited resources must be allocated among multiple tasks. Researchers have proposed both domain-specific, for example, spatial versus verbal processing resources, and domain general cognitive resources. In the present research, we investigated whether a spatial puzzle task performed simultaneously with a verbal recall task would impair performance in either task or both tasks, compared to performance on the tasks individually. As hypothesized, a reduction in word recall was found when dual-tasking, though performance on the puzzle task did not significantly differ between the single- and dual-task conditions. This is consistent, in part, with both a general resource theory and a Multiple Resource Theory, but further work is required to better understand the cognitive processing system. The employment of the recall task in the dual-task paradigm with a variety of secondary tasks will help to continue mapping out the specificity (or lack thereof) of cognitive resources utilized in various mental and physical tasks.

  12. Children's attention to task-relevant information accounts for relations between language and spatial cognition.

    Science.gov (United States)

    Miller, Hilary E; Simmering, Vanessa R

    2018-08-01

    Children's spatial language reliably predicts their spatial skills, but the nature of this relation is a source of debate. This investigation examined whether the mechanisms accounting for such relations are specific to language use or reflect a domain-general mechanism of selective attention. Experiment 1 examined whether 4-year-olds' spatial skills were predicted by their selective attention or their adaptive language use. Children completed (a) an attention task assessing attention to task-relevant color, size, and location cues; (b) a description task assessing adaptive language use to describe scenes varying in color, size, and location; and (c) three spatial tasks. There was correspondence between the cue types that children attended to and produced across description and attention tasks. Adaptive language use was predicted by both children's attention and task-related language production, suggesting that selective attention underlies skills in using language adaptively. After controlling for age, gender, receptive vocabulary, and adaptive language use, spatial skills were predicted by children's selective attention. The attention score predicted variance in spatial performance previously accounted for by adaptive language use. Experiment 2 followed up on the attention task (Experiment 2a) and description task (Experiment 2b) from Experiment 1 to assess whether performance in the tasks related to selective attention or task-specific demands. Performance in Experiments 2a and 2b paralleled that in Experiment 1, suggesting that the effects in Experiment 1 reflected children's selective attention skills. These findings show that selective attention is a central factor supporting spatial skill development that could account for many effects previously attributed to children's language use. Copyright © 2018 Elsevier Inc. All rights reserved.

  13. Novel behavioral tasks for studying spatial cognition in rats

    Czech Academy of Sciences Publication Activity Database

    Klement, Daniel; Blahna, Karel; Nekovářová, Tereza

    2008-01-01

    Roč. 57, Suppl.3 (2008), S161-S165 ISSN 0862-8408 R&D Projects: GA MŠk(CZ) LC554 Institutional research plan: CEZ:AV0Z50110509 Keywords : spatial cognition * moving objects * recognition Subject RIV: FH - Neurology Impact factor: 1.653, year: 2008

  14. Dual-task results and the lateralization of spatial orientation: artifact of test selection?

    Science.gov (United States)

    Bowers, C A; Milham, L M; Price, C

    1998-01-01

    An investigation was conducted to identify the degree to which results regarding the lateralization of spatial orientation among men and women are artifacts of test selection. A dual-task design was used to study possible lateralization differences, providing baseline and dual-task measures of spatial-orientation performance, right- and left-hand tapping, and vocalization of "cat, dog, horse." The Guilford-Zimmerman Test (Guilford & Zimmerman, 1953), the Eliot-Price Test (Eliot & Price, 1976), and the Stumpf-Fay Cube Perspectives Test (Stumpf & Fay, 1983) were the three spatial-orientation tests used to investigate possible artifacts of test selection. Twenty-eight right-handed male and 39 right-handed female undergraduates completed random baseline and dual-task sessions. Analyses indicated no significant sex-related differences in spatial-orientation ability for all three tests. Furthermore, there was no evidence of differential lateralization of spatial orientation between the sexes.

  15. Task-Management Method Using R-Tree Spatial Cloaking for Large-Scale Crowdsourcing

    Directory of Open Access Journals (Sweden)

    Yan Li

    2017-12-01

    Full Text Available With the development of sensor technology and the popularization of the data-driven service paradigm, spatial crowdsourcing systems have become an important way of collecting map-based location data. However, large-scale task management and location privacy are important factors for participants in spatial crowdsourcing. In this paper, we propose the use of an R-tree spatial cloaking-based task-assignment method for large-scale spatial crowdsourcing. We use an estimated R-tree based on the requested crowdsourcing tasks to reduce the crowdsourcing server-side inserting cost and enable the scalability. By using Minimum Bounding Rectangle (MBR-based spatial anonymous data without exact position data, this method preserves the location privacy of participants in a simple way. In our experiment, we showed that our proposed method is faster than the current method, and is very efficient when the scale is increased.

  16. Increased Task Demand during Spatial Memory Testing Recruits the Anterior Cingulate Cortex

    Science.gov (United States)

    Carr, Joshua K.; Fournier, Neil M.; Lehmann, Hugo

    2016-01-01

    We examined whether increasing retrieval difficulty in a spatial memory task would promote the recruitment of the anterior cingulate cortex (ACC) similar to what is typically observed during remote memory retrieval. Rats were trained on the hidden platform version of the Morris Water Task and tested three or 30 d later. Retrieval difficulty was…

  17. Cross-domain interference costs during concurrent verbal and spatial serial memory tasks are asymmetric

    NARCIS (Netherlands)

    Morey, Candice C.; Mall, Jonathan T.

    2012-01-01

    Some evidence suggests that memory for serial order is domain-general. Evidence also points to asymmetries in interference between verbal and visual-spatial tasks. We confirm that concurrently remembering verbal and spatial serial lists provokes substantial interference compared with remembering a

  18. Brain activity during auditory and visual phonological, spatial and simple discrimination tasks.

    Science.gov (United States)

    Salo, Emma; Rinne, Teemu; Salonen, Oili; Alho, Kimmo

    2013-02-16

    We used functional magnetic resonance imaging to measure human brain activity during tasks demanding selective attention to auditory or visual stimuli delivered in concurrent streams. Auditory stimuli were syllables spoken by different voices and occurring in central or peripheral space. Visual stimuli were centrally or more peripherally presented letters in darker or lighter fonts. The participants performed a phonological, spatial or "simple" (speaker-gender or font-shade) discrimination task in either modality. Within each modality, we expected a clear distinction between brain activations related to nonspatial and spatial processing, as reported in previous studies. However, within each modality, different tasks activated largely overlapping areas in modality-specific (auditory and visual) cortices, as well as in the parietal and frontal brain regions. These overlaps may be due to effects of attention common for all three tasks within each modality or interaction of processing task-relevant features and varying task-irrelevant features in the attended-modality stimuli. Nevertheless, brain activations caused by auditory and visual phonological tasks overlapped in the left mid-lateral prefrontal cortex, while those caused by the auditory and visual spatial tasks overlapped in the inferior parietal cortex. These overlapping activations reveal areas of multimodal phonological and spatial processing. There was also some evidence for intermodal attention-related interaction. Most importantly, activity in the superior temporal sulcus elicited by unattended speech sounds was attenuated during the visual phonological task in comparison with the other visual tasks. This effect might be related to suppression of processing irrelevant speech presumably distracting the phonological task involving the letters. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Crayfish Self-Administer Amphetamine in a Spatially Contingent Task

    Directory of Open Access Journals (Sweden)

    Udita Datta

    2018-05-01

    Full Text Available Natural reward is an essential element of any organism’s ability to adapt to environmental variation. Its underlying circuits and mechanisms guide the learning process as they help associate an event, or cue, with the perception of an outcome’s value. More generally, natural reward serves as the fundamental generator of all motivated behavior. Addictive plant alkaloids are able to activate this circuitry in taxa ranging from planaria to humans. With modularly organized nervous systems and confirmed vulnerabilities to human drugs of abuse, crayfish have recently emerged as a compelling model for the study of the addiction cycle, including psychostimulant effects, sensitization, withdrawal, reinstatement, and drug reward in conditioned place preference paradigms. Here we extend this work with the demonstration of a spatially contingent, operant drug self-administration paradigm for amphetamine. When the animal enters a quadrant of the arena with a particular textured substrate, a computer-based control system delivers amphetamine through an indwelling fine-bore cannula. Resulting reward strength, dose-response, and the time course of operant conditioning were assessed. Individuals experiencing the drug contingent on their behavior, displayed enhanced rates of operant responses compared to that of their yoked (non-contingent counterparts. Application of amphetamine near the supra-esophageal ganglion elicited stronger and more robust increases in operant responding than did systemic infusions. This work demonstrates automated implementation of a spatially contingent self-administration paradigm in crayfish, which provides a powerful tool to explore comparative perspectives in drug-sensitive reward, the mechanisms of learning underlying the addictive cycle, and phylogenetically conserved vulnerabilities to psychostimulant compounds.

  20. Detection of auditory signals in quiet and noisy backgrounds while performing a visuo-spatial task

    Directory of Open Access Journals (Sweden)

    Vishakha W Rawool

    2016-01-01

    Full Text Available Context: The ability to detect important auditory signals while performing visual tasks may be further compounded by background chatter. Thus, it is important to know how task performance may interact with background chatter to hinder signal detection. Aim: To examine any interactive effects of speech spectrum noise and task performance on the ability to detect signals. Settings and Design: The setting was a sound-treated booth. A repeated measures design was used. Materials and Methods: Auditory thresholds of 20 normal adults were determined at 0.5, 1, 2 and 4 kHz in the following conditions presented in a random order: (1 quiet with attention; (2 quiet with a visuo-spatial task or puzzle (distraction; (3 noise with attention and (4 noise with task. Statistical Analysis: Multivariate analyses of variance (MANOVA with three repeated factors (quiet versus noise, visuo-spatial task versus no task, signal frequency. Results: MANOVA revealed significant main effects for noise and signal frequency and significant noise–frequency and task–frequency interactions. Distraction caused by performing the task worsened the thresholds for tones presented at the beginning of the experiment and had no effect on tones presented in the middle. At the end of the experiment, thresholds (4 kHz were better while performing the task than those obtained without performing the task. These effects were similar across the quiet and noise conditions. Conclusion: Detection of auditory signals is difficult at the beginning of a distracting visuo-spatial task but over time, task learning and auditory training effects can nullify the effect of distraction and may improve detection of high frequency sounds.

  1. A Spatial Queuing-Based Algorithm for Multi-Robot Task Allocation

    Directory of Open Access Journals (Sweden)

    William Lenagh

    2015-08-01

    Full Text Available Multi-robot task allocation (MRTA is an important area of research in autonomous multi-robot systems. The main problem in MRTA is to allocate a set of tasks to a set of robots so that the tasks can be completed by the robots while ensuring that a certain metric, such as the time required to complete all tasks, or the distance traveled, or the energy expended by the robots is reduced. We consider a scenario where tasks can appear dynamically and a task needs to be performed by multiple robots to be completed. We propose a new algorithm called SQ-MRTA (Spatial Queueing-MRTA that uses a spatial queue-based model to allocate tasks between robots in a distributed manner. We have implemented the SQ-MRTA algorithm on accurately simulated models of Corobot robots within the Webots simulator for different numbers of robots and tasks and compared its performance with other state-of-the-art MRTA algorithms. Our results show that the SQ-MRTA algorithm is able to scale up with the number of tasks and robots in the environment, and it either outperforms or performs comparably with respect to other distributed MRTA algorithms.

  2. Poverty and social exclusion: An alternative spatial explanation

    Directory of Open Access Journals (Sweden)

    Krzysztofik Robert

    2017-03-01

    Full Text Available Poverty and social exclusion remain some of the biggest concerns in the face of obtaining social sustainability. In this respect, the continuing immense spatial differences between individual localities of seemingly similar characteristics have puzzled social scientists for decades. In quest for a better understanding, this article highlights the role of spatial heterogeneity as a factor conducive to the formation of functionally derelict areas, which in turn play a crucial role in the formation of spatial mismatch. Using two case studies from Poland, one from a big city and one from a small village, we explore the relationality between the phenomena of spatial heterogeneity, functional dereliction and spatial mismatch, whose mutual reinforcement seems to lead to a specific kind of deprivation in terms of scale and intensity. Special attention is paid to the role of spatial heterogeneity, which under certain conditions is capable of changing from being a developmental stimulant to becoming a destimulant. We argue that taking greater account of the intricate historical contexts responsible for the resistance of some pressing socio-economic problems is key to breaking the deadlock in the implementation of ineffective sustainability policies.

  3. Overshadowing of geometric cues by a beacon in a spatial navigation task.

    Science.gov (United States)

    Redhead, Edward S; Hamilton, Derek A; Parker, Matthew O; Chan, Wai; Allison, Craig

    2013-06-01

    In three experiments, we examined whether overshadowing of geometric cues by a discrete landmark (beacon) is due to the relative saliences of the cues. Using a virtual water maze task, human participants were required to locate a platform marked by a beacon in a distinctively shaped pool. In Experiment 1, the beacon overshadowed geometric cues in a trapezium, but not in an isosceles triangle. The longer escape latencies during acquisition in the trapezium control group with no beacon suggest that the geometric cues in the trapezium were less salient than those in the triangle. In Experiment 2, we evaluated whether generalization decrement, caused by the removal of the beacon at test, could account for overshadowing. An additional beacon was placed in an alternative corner. For the control groups, the beacons were identical; for the overshadow groups, they were visually unique. Overshadowing was again found in the trapezium. In Experiment 3, we tested whether the absence of overshadowing in the triangle was due to the geometric cues being more salient than the beacon. Following training, the beacon was relocated to a different corner. Participants approached the beacon rather than the trained platform corner, suggesting that the beacon was more salient. These results suggest that associative processes do not fully explain cue competition in the spatial domain.

  4. Sex Differences in Spatial Memory in Brown-Headed Cowbirds: Males Outperform Females on a Touchscreen Task.

    Directory of Open Access Journals (Sweden)

    Mélanie F Guigueno

    Full Text Available Spatial cognition in females and males can differ in species in which there are sex-specific patterns in the use of space. Brown-headed cowbirds are brood parasites that show a reversal of sex-typical space use often seen in mammals. Female cowbirds, search for, revisit and parasitize hosts nests, have a larger hippocampus than males and have better memory than males for a rewarded location in an open spatial environment. In the current study, we tested female and male cowbirds in breeding and non-breeding conditions on a touchscreen delayed-match-to-sample task using both spatial and colour stimuli. Our goal was to determine whether sex differences in spatial memory in cowbirds generalizes to all spatial tasks or is task-dependant. Both sexes performed better on the spatial than on the colour touchscreen task. On the spatial task, breeding males outperformed breeding females. On the colour task, females and males did not differ, but females performed better in breeding condition than in non-breeding condition. Although female cowbirds were observed to outperform males on a previous larger-scale spatial task, males performed better than females on a task testing spatial memory in the cowbirds' immediate visual field. Spatial abilities in cowbirds can favour males or females depending on the type of spatial task, as has been observed in mammals, including humans.

  5. Sex Differences in Spatial Memory in Brown-Headed Cowbirds: Males Outperform Females on a Touchscreen Task

    Science.gov (United States)

    Guigueno, Mélanie F.; MacDougall-Shackleton, Scott A.; Sherry, David F.

    2015-01-01

    Spatial cognition in females and males can differ in species in which there are sex-specific patterns in the use of space. Brown-headed cowbirds are brood parasites that show a reversal of sex-typical space use often seen in mammals. Female cowbirds, search for, revisit and parasitize hosts nests, have a larger hippocampus than males and have better memory than males for a rewarded location in an open spatial environment. In the current study, we tested female and male cowbirds in breeding and non-breeding conditions on a touchscreen delayed-match-to-sample task using both spatial and colour stimuli. Our goal was to determine whether sex differences in spatial memory in cowbirds generalizes to all spatial tasks or is task-dependant. Both sexes performed better on the spatial than on the colour touchscreen task. On the spatial task, breeding males outperformed breeding females. On the colour task, females and males did not differ, but females performed better in breeding condition than in non-breeding condition. Although female cowbirds were observed to outperform males on a previous larger-scale spatial task, males performed better than females on a task testing spatial memory in the cowbirds’ immediate visual field. Spatial abilities in cowbirds can favour males or females depending on the type of spatial task, as has been observed in mammals, including humans. PMID:26083573

  6. Alternative methods for skin irritation testing: the current status : ECVAM skin irritation task force report 1

    NARCIS (Netherlands)

    Botham, P.A.; Earl, L.K.; Fentem, J.H.; Roguet, R.; Sandt, J.J.M.

    1998-01-01

    The ECVAM Skin Irritation Task Force was established in November 1996, primarily to prepare a report on the current status of the development and validation of alternative tests for skin irritation and corrosion and, in particular, to identify any appropriate non-animal tests for predicting human

  7. Patterned-string tasks: relation between fine motor skills and visual-spatial abilities in parrots.

    Directory of Open Access Journals (Sweden)

    Anastasia Krasheninnikova

    Full Text Available String-pulling and patterned-string tasks are often used to analyse perceptual and cognitive abilities in animals. In addition, the paradigm can be used to test the interrelation between visual-spatial and motor performance. Two Australian parrot species, the galah (Eolophus roseicapilla and the cockatiel (Nymphicus hollandicus, forage on the ground, but only the galah uses its feet to manipulate food. I used a set of string pulling and patterned-string tasks to test whether usage of the feet during foraging is a prerequisite for solving the vertical string pulling problem. Indeed, the two species used techniques that clearly differed in the extent of beak-foot coordination but did not differ in terms of their success in solving the string pulling task. However, when the visual-spatial skills of the subjects were tested, the galahs outperformed the cockatiels. This supports the hypothesis that the fine motor skills needed for advanced beak-foot coordination may be interrelated with certain visual-spatial abilities needed for solving patterned-string tasks. This pattern was also found within each of the two species on the individual level: higher motor abilities positively correlated with performance in patterned-string tasks. This is the first evidence of an interrelation between visual-spatial and motor abilities in non-mammalian animals.

  8. Individual Differences in Verbal and Spatial Stroop Tasks: Interactive Role of Handedness and Domain

    Directory of Open Access Journals (Sweden)

    Mariagrazia Capizzi

    2017-11-01

    Full Text Available A longstanding debate in psychology concerns the relation between handedness and cognitive functioning. The present study aimed to contribute to this debate by comparing performance of right- and non-right-handers on verbal and spatial Stroop tasks. Previous studies have shown that non-right-handers have better inter-hemispheric interaction and greater access to right hemisphere processes. On this ground, we expected performance of right- and non-right-handers to differ on verbal and spatial Stroop tasks. Specifically, relative to right-handers, non-right-handers should have greater Stroop effect in the color-word Stroop task, for which inter-hemispheric interaction does not seem to be advantageous to performance. By contrast, non-right-handers should be better able to overcome interference in the spatial Stroop task. This is for their preferential access to the right hemisphere dealing with spatial material and their greater inter-hemispheric interaction with the left hemisphere hosting Stroop task processes. Our results confirmed these predictions, showing that handedness and the underlying brain asymmetries may be a useful variable to partly explain individual differences in executive functions.

  9. Brain functional network changes following Prelimbic area inactivation in a spatial memory extinction task.

    Science.gov (United States)

    Méndez-Couz, Marta; Conejo, Nélida M; Vallejo, Guillermo; Arias, Jorge L

    2015-01-01

    Several studies suggest a prefrontal cortex involvement during the acquisition and consolidation of spatial memory, suggesting an active modulating role at late stages of acquisition processes. Recently, we have reported that the prelimbic and infralimbic areas of the prefrontal cortex, among other structures, are also specifically involved in the late phases of spatial memory extinction. This study aimed to evaluate whether the inactivation of the prelimbic area of the prefrontal cortex impaired spatial memory extinction. For this purpose, male Wistar rats were implanted bilaterally with cannulae into the prelimbic region of the prefrontal cortex. Animals were trained during 5 consecutive days in a hidden platform task and tested for reference spatial memory immediately after the last training session. One day after completing the training task, bilateral infusion of the GABAA receptor agonist Muscimol was performed before the extinction protocol was carried out. Additionally, cytochrome c oxidase histochemistry was applied to map the metabolic brain activity related to the spatial memory extinction under prelimbic cortex inactivation. Results show that animals acquired the reference memory task in the water maze, and the extinction task was successfully completed without significant impairment. However, analysis of the functional brain networks involved by cytochrome oxidase activity interregional correlations showed changes in brain networks between the group treated with Muscimol as compared to the saline-treated group, supporting the involvement of the mammillary bodies at a the late stage in the memory extinction process. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Task demands affect spatial reference frame weighting during tactile localization in sighted and congenitally blind adults

    OpenAIRE

    Heed, Tobias; Roeder, Brigitte; Badde, Stephanie; Schubert, Jonathan

    2017-01-01

    Task demands modulate tactile localization in sighted humans, presumably through weight adjustments in the spatial integration of anatomical, skin-based, and external, posture-based information. In contrast, previous studies have suggested that congenitally blind humans, by default, refrain from automatic spatial integration and localize touch using only skin-based information. Here, sighted and congenitally blind participants localized tactile targets on the palm or back of one hand, while i...

  11. Spatially varying coefficient models in real estate: Eigenvector spatial filtering and alternative approaches

    NARCIS (Netherlands)

    Helbich, M; Griffith, D

    2016-01-01

    Real estate policies in urban areas require the recognition of spatial heterogeneity in housing prices to account for local settings. In response to the growing number of spatially varying coefficient models in housing applications, this study evaluated four models in terms of their spatial patterns

  12. Multi-tasking uncovers right spatial neglect and extinction in chronic left-hemisphere stroke patients.

    Science.gov (United States)

    Blini, Elvio; Romeo, Zaira; Spironelli, Chiara; Pitteri, Marco; Meneghello, Francesca; Bonato, Mario; Zorzi, Marco

    2016-11-01

    Unilateral Spatial Neglect, the most dramatic manifestation of contralesional space unawareness, is a highly heterogeneous syndrome. The presence of neglect is related to core spatially lateralized deficits, but its severity is also modulated by several domain-general factors (such as alertness or sustained attention) and by task demands. We previously showed that a computer-based dual-task paradigm exploiting both lateralized and non-lateralized factors (i.e., attentional load/multitasking) better captures this complex scenario and exacerbates deficits for the contralesional space after right hemisphere damage. Here we asked whether multitasking would reveal contralesional spatial disorders in chronic left-hemisphere damaged (LHD) stroke patients, a population in which impaired spatial processing is thought to be uncommon. Ten consecutive LHD patients with no signs of right-sided neglect at standard neuropsychological testing performed a computerized spatial monitoring task with and without concurrent secondary tasks (i.e., multitasking). Severe contralesional (right) space unawareness emerged in most patients under attentional load in both the visual and auditory modalities. Multitasking affected the detection of contralesional stimuli both when presented concurrently with an ipsilesional one (i.e., extinction for bilateral targets) and when presented in isolation (i.e., left neglect for right-sided targets). No spatial bias emerged in a control group of healthy elderly participants, who performed at ceiling, as well as in a second control group composed of patients with Mild Cognitive Impairment. We conclude that the pathological spatial asymmetry in LHD patients cannot be attributed to a global reduction of cognitive resources but it is the consequence of unilateral brain damage. Clinical and theoretical implications of the load-dependent lack of awareness for contralesional hemispace following LHD are discussed. Copyright © 2016. Published by Elsevier Ltd.

  13. A potential spatial working memory training task to improve both episodic memory and fluid intelligence.

    Directory of Open Access Journals (Sweden)

    Sarah R Rudebeck

    Full Text Available One current challenge in cognitive training is to create a training regime that benefits multiple cognitive domains, including episodic memory, without relying on a large battery of tasks, which can be time-consuming and difficult to learn. By giving careful consideration to the neural correlates underlying episodic and working memory, we devised a computerized working memory training task in which neurologically healthy participants were required to monitor and detect repetitions in two streams of spatial information (spatial location and scene identity presented simultaneously (i.e. a dual n-back paradigm. Participants' episodic memory abilities were assessed before and after training using two object and scene recognition memory tasks incorporating memory confidence judgments. Furthermore, to determine the generalizability of the effects of training, we also assessed fluid intelligence using a matrix reasoning task. By examining the difference between pre- and post-training performance (i.e. gain scores, we found that the trainers, compared to non-trainers, exhibited a significant improvement in fluid intelligence after 20 days. Interestingly, pre-training fluid intelligence performance, but not training task improvement, was a significant predictor of post-training fluid intelligence improvement, with lower pre-training fluid intelligence associated with greater post-training gain. Crucially, trainers who improved the most on the training task also showed an improvement in recognition memory as captured by d-prime scores and estimates of recollection and familiarity memory. Training task improvement was a significant predictor of gains in recognition and familiarity memory performance, with greater training improvement leading to more marked gains. In contrast, lower pre-training recollection memory scores, and not training task improvement, led to greater recollection memory performance after training. Our findings demonstrate that practice

  14. Prefrontal spatial working memory network predicts animal's decision making in a free choice saccade task.

    Science.gov (United States)

    Mochizuki, Kei; Funahashi, Shintaro

    2016-01-01

    While neurons in the lateral prefrontal cortex (PFC) encode spatial information during the performance of working memory tasks, they are also known to participate in subjective behavior such as spatial attention and action selection. In the present study, we analyzed the activity of primate PFC neurons during the performance of a free choice memory-guided saccade task in which the monkeys needed to choose a saccade direction by themselves. In trials when the receptive field location was subsequently chosen by the animal, PFC neurons with spatially selective visual response started to show greater activation before cue onset. This result suggests that the fluctuation of firing before cue presentation prematurely biased the representation of a certain spatial location and eventually encouraged the subsequent choice of that location. In addition, modulation of the activity by the animal's choice was observed only in neurons with high sustainability of activation and was also dependent on the spatial configuration of the visual cues. These findings were consistent with known characteristics of PFC neurons in information maintenance in spatial working memory function. These results suggest that precue fluctuation of spatial representation was shared and enhanced through the working memory network in the PFC and could finally influence the animal's free choice of saccade direction. The present study revealed that the PFC plays an important role in decision making in a free choice condition and that the dynamics of decision making are constrained by the network architecture embedded in this cortical area. Copyright © 2016 the American Physiological Society.

  15. Prefrontal spatial working memory network predicts animal's decision making in a free choice saccade task

    Science.gov (United States)

    Mochizuki, Kei

    2015-01-01

    While neurons in the lateral prefrontal cortex (PFC) encode spatial information during the performance of working memory tasks, they are also known to participate in subjective behavior such as spatial attention and action selection. In the present study, we analyzed the activity of primate PFC neurons during the performance of a free choice memory-guided saccade task in which the monkeys needed to choose a saccade direction by themselves. In trials when the receptive field location was subsequently chosen by the animal, PFC neurons with spatially selective visual response started to show greater activation before cue onset. This result suggests that the fluctuation of firing before cue presentation prematurely biased the representation of a certain spatial location and eventually encouraged the subsequent choice of that location. In addition, modulation of the activity by the animal's choice was observed only in neurons with high sustainability of activation and was also dependent on the spatial configuration of the visual cues. These findings were consistent with known characteristics of PFC neurons in information maintenance in spatial working memory function. These results suggest that precue fluctuation of spatial representation was shared and enhanced through the working memory network in the PFC and could finally influence the animal's free choice of saccade direction. The present study revealed that the PFC plays an important role in decision making in a free choice condition and that the dynamics of decision making are constrained by the network architecture embedded in this cortical area. PMID:26490287

  16. Attention, spatial integration, and the tail of response time distributions in Stroop task performance

    NARCIS (Netherlands)

    Roelofs, A.P.A.

    2012-01-01

    A few studies have examined selective attention in Stroop task performance through ex-Gaussian analyses of response time (RT) distributions. It has remained unclear whether the tail of the RT distribution in vocal responding reflects spatial integration of relevant and irrelevant attributes, as

  17. Investigating the time course of tactile reflexive attention using a non-spatial discrimination task.

    Science.gov (United States)

    Miles, Eleanor; Poliakoff, Ellen; Brown, Richard J

    2008-06-01

    Peripheral cues are thought to facilitate responses to stimuli presented at the same location because they lead to exogenous attention shifts. Facilitation has been observed in numerous studies of visual and auditory attention, but there have been only four demonstrations of tactile facilitation, all in studies with potential confounds. Three studies used a spatial (finger versus thumb) discrimination task, where the cue could have provided a spatial framework that might have assisted the discrimination of subsequent targets presented on the same side as the cue. The final study circumvented this problem by using a non-spatial discrimination; however, the cues were informative and interspersed with visual cues which may have affected the attentional effects observed. In the current study, therefore, we used a non-spatial tactile frequency discrimination task following a non-informative tactile white noise cue. When the target was presented 150 ms after the cue, we observed faster discrimination responses to targets presented on the same side compared to the opposite side as the cue; by 1000 ms, responses were significantly faster to targets presented on the opposite side to the cue. Thus, we demonstrated that tactile attentional facilitation can be observed in a non-spatial discrimination task, under unimodal conditions and with entirely non-predictive cues. Furthermore, we provide the first demonstration of significant tactile facilitation and tactile inhibition of return within a single experiment.

  18. Task and spatial frequency modulations of object processing: an EEG study.

    Directory of Open Access Journals (Sweden)

    Matt Craddock

    Full Text Available Visual object processing may follow a coarse-to-fine sequence imposed by fast processing of low spatial frequencies (LSF and slow processing of high spatial frequencies (HSF. Objects can be categorized at varying levels of specificity: the superordinate (e.g. animal, the basic (e.g. dog, or the subordinate (e.g. Border Collie. We tested whether superordinate and more specific categorization depend on different spatial frequency ranges, and whether any such dependencies might be revealed by or influence signals recorded using EEG. We used event-related potentials (ERPs and time-frequency (TF analysis to examine the time course of object processing while participants performed either a grammatical gender-classification task (which generally forces basic-level categorization or a living/non-living judgement (superordinate categorization on everyday, real-life objects. Objects were filtered to contain only HSF or LSF. We found a greater positivity and greater negativity for HSF than for LSF pictures in the P1 and N1 respectively, but no effects of task on either component. A later, fronto-central negativity (N350 was more negative in the gender-classification task than the superordinate categorization task, which may indicate that this component relates to semantic or syntactic processing. We found no significant effects of task or spatial frequency on evoked or total gamma band responses. Our results demonstrate early differences in processing of HSF and LSF content that were not modulated by categorization task, with later responses reflecting such higher-level cognitive factors.

  19. Task and spatial frequency modulations of object processing: an EEG study.

    Science.gov (United States)

    Craddock, Matt; Martinovic, Jasna; Müller, Matthias M

    2013-01-01

    Visual object processing may follow a coarse-to-fine sequence imposed by fast processing of low spatial frequencies (LSF) and slow processing of high spatial frequencies (HSF). Objects can be categorized at varying levels of specificity: the superordinate (e.g. animal), the basic (e.g. dog), or the subordinate (e.g. Border Collie). We tested whether superordinate and more specific categorization depend on different spatial frequency ranges, and whether any such dependencies might be revealed by or influence signals recorded using EEG. We used event-related potentials (ERPs) and time-frequency (TF) analysis to examine the time course of object processing while participants performed either a grammatical gender-classification task (which generally forces basic-level categorization) or a living/non-living judgement (superordinate categorization) on everyday, real-life objects. Objects were filtered to contain only HSF or LSF. We found a greater positivity and greater negativity for HSF than for LSF pictures in the P1 and N1 respectively, but no effects of task on either component. A later, fronto-central negativity (N350) was more negative in the gender-classification task than the superordinate categorization task, which may indicate that this component relates to semantic or syntactic processing. We found no significant effects of task or spatial frequency on evoked or total gamma band responses. Our results demonstrate early differences in processing of HSF and LSF content that were not modulated by categorization task, with later responses reflecting such higher-level cognitive factors.

  20. Genomic organization and the tissue distribution of alternatively spliced isoforms of the mouse Spatial gene

    Directory of Open Access Journals (Sweden)

    Mattei Marie-Geneviève

    2004-07-01

    Full Text Available Abstract Background The stromal component of the thymic microenvironment is critical for T lymphocyte generation. Thymocyte differentiation involves a cascade of coordinated stromal genes controlling thymocyte survival, lineage commitment and selection. The "Stromal Protein Associated with Thymii And Lymph-node" (Spatial gene encodes a putative transcription factor which may be involved in T-cell development. In the testis, the Spatial gene is also expressed by round spermatids during spermatogenesis. Results The Spatial gene maps to the B3-B4 region of murine chromosome 10 corresponding to the human syntenic region 10q22.1. The mouse Spatial genomic DNA is organised into 10 exons and is alternatively spliced to generate two short isoforms (Spatial-α and -γ and two other long isoforms (Spatial-δ and -ε comprising 5 additional exons on the 3' site. Here, we report the cloning of a new short isoform, Spatial-β, which differs from other isoforms by an additional alternative exon of 69 bases. This new exon encodes an interesting proline-rich signature that could confer to the 34 kDa Spatial-β protein a particular function. By quantitative TaqMan RT-PCR, we have shown that the short isoforms are highly expressed in the thymus while the long isoforms are highly expressed in the testis. We further examined the inter-species conservation of Spatial between several mammals and identified that the protein which is rich in proline and positive amino acids, is highly conserved. Conclusions The Spatial gene generates at least five alternative spliced variants: three short isoforms (Spatial-α, -β and -γ highly expressed in the thymus and two long isoforms (Spatial-δ and -ε highly expressed in the testis. These alternative spliced variants could have a tissue specific function.

  1. Linking linear programming and spatial simulation models to predict landscape effects of forest management alternatives

    Science.gov (United States)

    Eric J. Gustafson; L. Jay Roberts; Larry A. Leefers

    2006-01-01

    Forest management planners require analytical tools to assess the effects of alternative strategies on the sometimes disparate benefits from forests such as timber production and wildlife habitat. We assessed the spatial patterns of alternative management strategies by linking two models that were developed for different purposes. We used a linear programming model (...

  2. Common mechanisms of spatial attention in memory and perception: a tactile dual-task study.

    Science.gov (United States)

    Katus, Tobias; Andersen, Søren K; Müller, Matthias M

    2014-03-01

    Orienting attention to locations in mnemonic representations engages processes that functionally and anatomically overlap the neural circuitry guiding prospective shifts of spatial attention. The attention-based rehearsal account predicts that the requirement to withdraw attention from a memorized location impairs memory accuracy. In a dual-task study, we simultaneously presented retro-cues and pre-cues to guide spatial attention in short-term memory (STM) and perception, respectively. The spatial direction of each cue was independent of the other. The locations indicated by the combined cues could be compatible (same hand) or incompatible (opposite hands). Incompatible directional cues decreased lateralized activity in brain potentials evoked by visual cues, indicating interference in the generation of prospective attention shifts. The detection of external stimuli at the prospectively cued location was impaired when the memorized location was part of the perceptually ignored hand. The disruption of attention-based rehearsal by means of incompatible pre-cues reduced memory accuracy and affected encoding of tactile test stimuli at the retrospectively cued hand. These findings highlight the functional significance of spatial attention for spatial STM. The bidirectional interactions between both tasks demonstrate that spatial attention is a shared neural resource of a capacity-limited system that regulates information processing in internal and external stimulus representations.

  3. Real-time changes in hippocampal energy demands during a spatial working memory task.

    Science.gov (United States)

    Kealy, John; Bennett, Rachel; Woods, Barbara; Lowry, John P

    2017-05-30

    Activity-dependent changes in hippocampal energy consumption have largely been determined using microdialysis. However, real-time recordings of brain energy consumption can be more accurately achieved using amperometric sensors, allowing for sensitive real-time monitoring of concentration changes. Here, we test the theory that systemic pre-treatment with glucose in rats prevents activity-dependent decreases in hippocampal glucose levels and thus enhances their performance in a spontaneous alternation task. Male Sprague Dawley rats were implanted into the hippocampus with either: 1) microdialysis probe; or 2) an oxygen sensor and glucose biosensor co-implanted together. Animals were pre-treated with either saline or glucose (250mg/kg) 30min prior to performing a single 20-min spontaneous alternation task in a +-maze. There were no significant differences found between either treatment group in terms of spontaneous alternation performance. Additionally, there was a significant difference found between treatment groups on hippocampal glucose levels measured using microdialysis (a decrease associated with glucose pre-treatment in control animals) but not amperometry. There were significant increases in hippocampal oxygen during +-maze exploration. Combining the findings from both methods, it appears that hippocampal activity in the spontaneous alternation task does not cause an increase in glucose consumption, despite an increase in regional cerebral blood flow (using oxygen supply as an index of blood flow) and, as such, pre-treatment with glucose does not enhance spontaneous alternation performance. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Spatial perseveration error by alpacas (Vicugna pacos) in an A-not-B detour task.

    Science.gov (United States)

    Abramson, José Z; Paulina Soto, D; Beatriz Zapata, S; Lloreda, María Victoria Hernández

    2018-05-01

    Spatial perseveration has been documented for domestic animals such as mules, donkeys, horses and dogs. However, evidence for this spatial cognition behavior among other domestic species is scarce. Alpacas have been domesticated for at least 7000 years yet their cognitive ability has not been officially reported. The present article used an A-not-B detour task to study the spatial problem-solving abilities of alpacas (Vicugna pacos) and to identify the perseveration errors, which refers to a tendency to maintain a learned route, despite having another available path. The study tested 51 alpacas, which had to pass through a gap at one end of a barrier in order to reach a reward. After one, two, three or four repeats (A trials), the gap was moved to the opposite end of the barrier (B trials). In contrast to what has been found in other domestic animals tested with the same task, the present study did not find clear evidence of spatial perseveration. Individuals' performance in the subsequent B trials, following the change of gap location, suggests no error persistence in alpacas. Results suggest that alpacas are more flexible than other domestic animals tested with this same task, which has important implications in planning proper training for experimental designs or productive purposes. These results could contribute toward enhancing alpacas' welfare and our understanding of their cognitive abilities.

  5. Coherent visualization of spatial data adapted to roles, tasks, and hardware

    Science.gov (United States)

    Wagner, Boris; Peinsipp-Byma, Elisabeth

    2012-06-01

    Modern crisis management requires that users with different roles and computer environments have to deal with a high volume of various data from different sources. For this purpose, Fraunhofer IOSB has developed a geographic information system (GIS) which supports the user depending on available data and the task he has to solve. The system provides merging and visualization of spatial data from various civilian and military sources. It supports the most common spatial data standards (OGC, STANAG) as well as some proprietary interfaces, regardless if these are filebased or database-based. To set the visualization rules generic Styled Layer Descriptors (SLDs) are used, which are an Open Geospatial Consortium (OGC) standard. SLDs allow specifying which data are shown, when and how. The defined SLDs consider the users' roles and task requirements. In addition it is possible to use different displays and the visualization also adapts to the individual resolution of the display. Too high or low information density is avoided. Also, our system enables users with different roles to work together simultaneously using the same data base. Every user is provided with the appropriate and coherent spatial data depending on his current task. These so refined spatial data are served via the OGC services Web Map Service (WMS: server-side rendered raster maps), or the Web Map Tile Service - (WMTS: pre-rendered and cached raster maps).

  6. Horses fail to use social learning when solving spatial detour tasks

    DEFF Research Database (Denmark)

    Rørvang, Maria Vilain; Peerstrup Ahrendt, Line; Christensen, Janne Winther

    2015-01-01

    Social animals should have plenty of opportunities to learn from conspecifics, but most studies have failed to document social learning in horses. This study investigates whether young Icelandic horses can learn a spatial detour task through observation of a trained demonstrator horse of either...... the same age (Experiments 1 and 2, n = 22) or older (Experiment 3, n = 24). Observer horses were allowed to observe the demonstrator being led three times through the detour route immediately before being given the opportunity to solve the task themselves. Controls were allowed only to observe...

  7. Dynamic spatial coding within the dorsal frontoparietal network during a visual search task.

    Directory of Open Access Journals (Sweden)

    Wieland H Sommer

    Full Text Available To what extent are the left and right visual hemifields spatially coded in the dorsal frontoparietal attention network? In many experiments with neglect patients, the left hemisphere shows a contralateral hemifield preference, whereas the right hemisphere represents both hemifields. This pattern of spatial coding is often used to explain the right-hemispheric dominance of lesions causing hemispatial neglect. However, pathophysiological mechanisms of hemispatial neglect are controversial because recent experiments on healthy subjects produced conflicting results regarding the spatial coding of visual hemifields. We used an fMRI paradigm that allowed us to distinguish two attentional subprocesses during a visual search task. Either within the left or right hemifield subjects first attended to stationary locations (spatial orienting and then shifted their attentional focus to search for a target line. Dynamic changes in spatial coding of the left and right hemifields were observed within subregions of the dorsal front-parietal network: During stationary spatial orienting, we found the well-known spatial pattern described above, with a bilateral hemifield representation in the right hemisphere and a contralateral preference in the left hemisphere. However, during search, the right hemisphere had a contralateral preference and the left hemisphere equally represented both hemifields. This finding leads to novel perspectives regarding models of visuospatial attention and hemispatial neglect.

  8. An fMRI study of sex differences in regional activation to a verbal and a spatial task.

    Science.gov (United States)

    Gur, R C; Alsop, D; Glahn, D; Petty, R; Swanson, C L; Maldjian, J A; Turetsky, B I; Detre, J A; Gee, J; Gur, R E

    2000-09-01

    Sex differences in cognitive performance have been documented, women performing better on some phonological tasks and men on spatial tasks. An earlier fMRI study suggested sex differences in distributed brain activation during phonological processing, with bilateral activation seen in women while men showed primarily left-lateralized activation. This blood oxygen level-dependent fMRI study examined sex differences (14 men, 13 women) in activation for a spatial task (judgment of line orientation) compared to a verbal-reasoning task (analogies) that does not typically show sex differences. Task difficulty was manipulated. Hypothesized ROI-based analysis documented the expected left-lateralized changes for the verbal task in the inferior parietal and planum temporal regions in both men and women, but only men showed right-lateralized increase for the spatial task in these regions. Image-based analysis revealed a distributed network of cortical regions activated by the tasks, which consisted of the lateral frontal, medial frontal, mid-temporal, occipitoparietal, and occipital regions. The activation was more left lateralized for the verbal and more right for the spatial tasks, but men also showed some left activation for the spatial task, which was not seen in women. Increased task difficulty produced more distributed activation for the verbal and more circumscribed activation for the spatial task. The results suggest that failure to activate the appropriate hemisphere in regions directly involved in task performance may explain certain sex differences in performance. They also extend, for a spatial task, the principle that bilateral activation in a distributed cognitive system underlies sex differences in performance. Copyright 2000 Academic Press.

  9. Group social rank is associated with performance on a spatial learning task.

    Science.gov (United States)

    Langley, Ellis J G; van Horik, Jayden O; Whiteside, Mark A; Madden, Joah R

    2018-02-01

    Dominant individuals differ from subordinates in their performances on cognitive tasks across a suite of taxa. Previous studies often only consider dyadic relationships, rather than the more ecologically relevant social hierarchies or networks, hence failing to account for how dyadic relationships may be adjusted within larger social groups. We used a novel statistical method: randomized Elo-ratings, to infer the social hierarchy of 18 male pheasants, Phasianus colchicus , while in a captive, mixed-sex group with a linear hierarchy. We assayed individual learning performance of these males on a binary spatial discrimination task to investigate whether inter-individual variation in performance is associated with group social rank. Task performance improved with increasing trial number and was positively related to social rank, with higher ranking males showing greater levels of success. Motivation to participate in the task was not related to social rank or task performance, thus indicating that these rank-related differences are not a consequence of differences in motivation to complete the task. Our results provide important information about how variation in cognitive performance relates to an individual's social rank within a group. Whether the social environment causes differences in learning performance or instead, inherent differences in learning ability predetermine rank remains to be tested.

  10. IEA combustion agreement : a collaborative task on alternative fuels in combustion

    International Nuclear Information System (INIS)

    Larmi, M.

    2009-01-01

    The focus of the alternative fuels in combustion task of the International Energy Agency is on high efficiency engine combustion, furnace combustion, and combustion chemistry. The objectives of the task are to develop optimum combustion for dedicated fuels by fully utilizing the physical and chemical properties of synthetic and renewable fuels; a significant reduction in carbon dioxide, NOx and particulate matter emissions; determine the minimum emission levels for dedicated fuels; and meet future emission standards of engines without or with minimum after-treatment. This presentation discussed the alternative fuels task and addressed issues such as synthetic fuel properties and benefits. The anticipated future roadmap was presented along with a list of the synthetic and renewable engine fuels to be studied, such as neat oxygenates like alcohols and ethers, biogas/methane and gas combustion, fuel blends, dual fuel combustion, high cetane number diesel fuels like synthetic Fischer-Tropsch diesel fuel and hydrogenated vegetable oil, and low CN number fuels. Implementation examples were also discussed, such as fuel spray studies in optical spray bombs; combustion research in optical engines and combustion chambers; studies on reaction kinetics of combustion and emission formation; studies on fuel properties and ignition behaviour; combustion studies on research engines; combustion optimization; implementing the optimum combustion in research engines; and emission measurements. Overall milestone examples and the overall schedule of participating countries were also presented. figs.

  11. Task demands affect spatial reference frame weighting during tactile localization in sighted and congenitally blind adults.

    Directory of Open Access Journals (Sweden)

    Jonathan T W Schubert

    Full Text Available Task demands modulate tactile localization in sighted humans, presumably through weight adjustments in the spatial integration of anatomical, skin-based, and external, posture-based information. In contrast, previous studies have suggested that congenitally blind humans, by default, refrain from automatic spatial integration and localize touch using only skin-based information. Here, sighted and congenitally blind participants localized tactile targets on the palm or back of one hand, while ignoring simultaneous tactile distractors at congruent or incongruent locations on the other hand. We probed the interplay of anatomical and external location codes for spatial congruency effects by varying hand posture: the palms either both faced down, or one faced down and one up. In the latter posture, externally congruent target and distractor locations were anatomically incongruent and vice versa. Target locations had to be reported either anatomically ("palm" or "back" of the hand, or externally ("up" or "down" in space. Under anatomical instructions, performance was more accurate for anatomically congruent than incongruent target-distractor pairs. In contrast, under external instructions, performance was more accurate for externally congruent than incongruent pairs. These modulations were evident in sighted and blind individuals. Notably, distractor effects were overall far smaller in blind than in sighted participants, despite comparable target-distractor identification performance. Thus, the absence of developmental vision seems to be associated with an increased ability to focus tactile attention towards a non-spatially defined target. Nevertheless, that blind individuals exhibited effects of hand posture and task instructions in their congruency effects suggests that, like the sighted, they automatically integrate anatomical and external information during tactile localization. Moreover, spatial integration in tactile processing is, thus, flexibly

  12. Task demands affect spatial reference frame weighting during tactile localization in sighted and congenitally blind adults.

    Science.gov (United States)

    Schubert, Jonathan T W; Badde, Stephanie; Röder, Brigitte; Heed, Tobias

    2017-01-01

    Task demands modulate tactile localization in sighted humans, presumably through weight adjustments in the spatial integration of anatomical, skin-based, and external, posture-based information. In contrast, previous studies have suggested that congenitally blind humans, by default, refrain from automatic spatial integration and localize touch using only skin-based information. Here, sighted and congenitally blind participants localized tactile targets on the palm or back of one hand, while ignoring simultaneous tactile distractors at congruent or incongruent locations on the other hand. We probed the interplay of anatomical and external location codes for spatial congruency effects by varying hand posture: the palms either both faced down, or one faced down and one up. In the latter posture, externally congruent target and distractor locations were anatomically incongruent and vice versa. Target locations had to be reported either anatomically ("palm" or "back" of the hand), or externally ("up" or "down" in space). Under anatomical instructions, performance was more accurate for anatomically congruent than incongruent target-distractor pairs. In contrast, under external instructions, performance was more accurate for externally congruent than incongruent pairs. These modulations were evident in sighted and blind individuals. Notably, distractor effects were overall far smaller in blind than in sighted participants, despite comparable target-distractor identification performance. Thus, the absence of developmental vision seems to be associated with an increased ability to focus tactile attention towards a non-spatially defined target. Nevertheless, that blind individuals exhibited effects of hand posture and task instructions in their congruency effects suggests that, like the sighted, they automatically integrate anatomical and external information during tactile localization. Moreover, spatial integration in tactile processing is, thus, flexibly adapted by top

  13. Gaze movements and spatial working memory in collision avoidance: a traffic intersection task

    Directory of Open Access Journals (Sweden)

    Gregor eHardiess

    2013-06-01

    Full Text Available Street crossing under traffic is an everyday activity including collision detection as well as avoidance of objects in the path of motion. Such tasks demand extraction and representation of spatio-temporal information about relevant obstacles in an optimized format. Relevant task information is extracted visually by the use of gaze movements and represented in spatial working memory. In a virtual reality traffic intersection task, subjects are confronted with a two-lane intersection where cars are appearing with different frequencies, corresponding to high and low traffic densities. Under free observation and exploration of the scenery (using unrestricted eye and head movements the overall task for the subjects was to predict the potential-of-collision (POC of the cars or to adjust an adequate driving speed in order to cross the intersection without collision (i.e., to find the free space for crossing. In a series of experiments, gaze movement parameters, task performance, and the representation of car positions within working memory at distinct time points were assessed in normal subjects as well as in neurological patients suffering from homonymous hemianopia. In the following, we review the findings of these experiments together with other studies and provide a new perspective of the role of gaze behavior and spatial memory in collision detection and avoidance, focusing on the following questions: (i which sensory variables can be identified supporting adequate collision detection? (ii How do gaze movements and working memory contribute to collision avoidance when multiple moving objects are present and (iii how do they correlate with task performance? (iv How do patients with homonymous visual field defects use gaze movements and working memory to compensate for visual field loss? In conclusion, we extend the theory of collision detection and avoidance in the case of multiple moving objects and provide a new perspective on the combined

  14. Cognitive correlates of spatial navigation: Associations between executive functioning and the virtual Morris Water Task.

    Science.gov (United States)

    Korthauer, L E; Nowak, N T; Frahmand, M; Driscoll, I

    2017-01-15

    Although effective spatial navigation requires memory for objects and locations, navigating a novel environment may also require considerable executive resources. The present study investigated associations between performance on the virtual Morris Water Task (vMWT), an analog version of a nonhuman spatial navigation task, and neuropsychological tests of executive functioning and spatial performance in 75 healthy young adults. More effective vMWT performance (e.g., lower latency and distance to reach hidden platform, greater distance in goal quadrant on a probe trial, fewer path intersections) was associated with better verbal fluency, set switching, response inhibition, and ability to mentally rotate objects. Findings also support a male advantage in spatial navigation, with sex moderating several associations between vMWT performance and executive abilities. Overall, we report a robust relationship between executive functioning and navigational skill, with some evidence that men and women may differentially recruit cognitive abilities when navigating a novel environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Reducing motion sickness - A comparison of autogenic-feedback training and an alternative cognitive task

    Science.gov (United States)

    Toscano, W. B.; Cowings, P. S.

    1982-01-01

    Eighteen men were randomly assigned to three groups matched for susceptibility to Coriolis motion sickness. All subjects were given six Coriolis Sickness Susceptibility Index (CSSI) tests separated by 5-d intervals. Treatment Group I subjects were taught to control their own autonomic responses before the third, fourth, and fifth CSSI tests (6 h total training). Group II subjects were given 'sham' training in an alternative cognitive task under conditions otherwise identical to those of Group I. Group III subjects received no treatment. Results showed that Group I subjects could withstand the stress of Coriolis acceleration significantly longer after training. Neither of the other two groups changed significantly.

  16. High and low schizotypal female subjects do not differ in spatial memory abilities in a virtual reality task.

    Science.gov (United States)

    García-Montes, José Manuel; Noguera, Carmen; Alvarez, Dolores; Ruiz, Marina; Cimadevilla Redondo, José Manuel

    2014-01-01

    Schizotypy is a psychological construct related to schizophrenia. The exact relationship between both entities is not clear. In recent years, schizophrenia has been associated with hippocampal abnormalities and spatial memory problems. The aim of this study was to determine possible links between high schizotypy (HS) and low schizotypy (LS) and spatial abilities, using virtual reality tasks. We hypothesised that the HS group would exhibit a lower performance in spatial memory tasks than the LS group. Two groups of female students were formed according to their score on the ESQUIZO-Q-A questionnaire. HS and LS subjects were tested on two different tasks: the Boxes Room task, a spatial memory task sensitive to hippocampal alterations and a spatial recognition task. Data showed that both groups mastered both tasks. Groups differed in personality features but not in spatial performance. These results provide valuable information about the schizotypy-schizophrenia connections. Schizotypal subjects are not impaired on spatial cognition and, accordingly, the schizotypy-schizophrenia relationship is not straightforward.

  17. Flexible spatial perspective-taking: Conversational partners weigh multiple cues in collaborative tasks

    Directory of Open Access Journals (Sweden)

    Alexia eGalati

    2013-09-01

    non-spatial tasks.

  18. Flexible spatial perspective-taking: conversational partners weigh multiple cues in collaborative tasks.

    Science.gov (United States)

    Galati, Alexia; Avraamides, Marios N

    2013-01-01

    Research on spatial perspective-taking often focuses on the cognitive processes of isolated individuals as they adopt or maintain imagined perspectives. Collaborative studies of spatial perspective-taking typically examine speakers' linguistic choices, while overlooking their underlying processes and representations. We review evidence from two collaborative experiments that examine the contribution of social and representational cues to spatial perspective choices in both language and the organization of spatial memory. Across experiments, speakers organized their memory representations according to the convergence of various cues. When layouts were randomly configured and did not afford intrinsic cues, speakers encoded their partner's viewpoint in memory, if available, but did not use it as an organizing direction. On the other hand, when the layout afforded an intrinsic structure, speakers organized their spatial memories according to the person-centered perspective reinforced by the layout's structure. Similarly, in descriptions, speakers considered multiple cues whether available a priori or at the interaction. They used partner-centered expressions more frequently (e.g., "to your right") when the partner's viewpoint was misaligned by a small offset or coincided with the layout's structure. Conversely, they used egocentric expressions more frequently when their own viewpoint coincided with the intrinsic structure or when the partner was misaligned by a computationally difficult, oblique offset. Based on these findings we advocate for a framework for flexible perspective-taking: people weigh multiple cues (including social ones) to make attributions about the relative difficulty of perspective-taking for each partner, and adapt behavior to minimize their collective effort. This framework is not specialized for spatial reasoning but instead emerges from the same principles and memory-depended processes that govern perspective-taking in non-spatial tasks.

  19. Deficits of spatial and task-related attentional selection in mild cognitive impairment and Alzheimer's disease.

    Science.gov (United States)

    Redel, P; Bublak, P; Sorg, C; Kurz, A; Förstl, H; Müller, H J; Schneider, W X; Perneczky, R; Finke, K

    2012-01-01

    Visual selective attention was assessed with a partial-report task in patients with probable Alzheimer's disease (AD), amnestic mild cognitive impairment (MCI), and healthy elderly controls. Based on Bundesen's "theory of visual attention" (TVA), two parameters were derived: top-down control of attentional selection, representing task-related attentional weighting for prioritizing relevant visual objects, and spatial distribution of attentional weights across the left and the right hemifield. Compared with controls, MCI patients showed significantly reduced top-down controlled selection, which was further deteriorated in AD subjects. Moreover, attentional weighting was significantly unbalanced across hemifields in MCI and tended to be more lateralized in AD. Across MCI and AD patients, carriers of the apolipoprotein E ε4 allele (ApoE4) displayed a leftward spatial bias, which was the more pronounced the younger the ApoE4-positive patients and the earlier disease onset. These results indicate that impaired top-down control may be linked to early dysfunction of fronto-parietal networks. An early temporo-parietal interhemispheric asymmetry might cause a pathological spatial bias which is associated with ApoE4 genotype and may therefore function as early cognitive marker of upcoming AD. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Assessment of Spatial Navigation and Docking Performance During Simulated Rover Tasks

    Science.gov (United States)

    Wood, S. J.; Dean, S. L.; De Dios, Y. E.; Moore, S. T.

    2010-01-01

    INTRODUCTION: Following long-duration exploration transits, pressurized rovers will enhance surface mobility to explore multiple sites across Mars and other planetary bodies. Multiple rovers with docking capabilities are envisioned to expand the range of exploration. However, adaptive changes in sensorimotor and cognitive function may impair the crew s ability to safely navigate and perform docking tasks shortly after transition to the new gravitoinertial environment. The primary goal of this investigation is to quantify post-flight decrements in spatial navigation and docking performance during a rover simulation. METHODS: Eight crewmembers returning from the International Space Station will be tested on a motion simulator during four pre-flight and three post-flight sessions over the first 8 days following landing. The rover simulation consists of a serial presentation of discrete tasks to be completed within a scheduled 10 min block. The tasks are based on navigating around a Martian outpost spread over a 970 sq m terrain. Each task is subdivided into three components to be performed as quickly and accurately as possible: (1) Perspective taking: Subjects use a joystick to indicate direction of target after presentation of a map detailing current orientation and location of the rover with the task to be performed. (2) Navigation: Subjects drive the rover to the desired location while avoiding obstacles. (3) Docking: Fine positioning of the rover is required to dock with another object or align a camera view. Overall operator proficiency will be based on how many tasks the crewmember can complete during the 10 min time block. EXPECTED RESULTS: Functionally relevant testing early post-flight will develop evidence regarding the limitations to early surface operations and what countermeasures are needed. This approach can be easily adapted to a wide variety of simulated vehicle designs to provide sensorimotor assessments for other operational and civilian populations.

  1. Computerized spatial delayed recognition span task: a specific tool to assess visuospatial working memory.

    Science.gov (United States)

    Satler, Corina; Belham, Flávia Schechtman; Garcia, Ana; Tomaz, Carlos; Tavares, Maria Clotilde H

    2015-01-01

    A new tablet device version (IOS platform) of the Spatial Delayed Recognition Span Task (SDRST) was developed with the aim of investigating visuospatial Working Memory (WM) abilities based on touchscreen technology. This new WM testing application will be available to download for free in Apple Store app ("SDRST app"). In order to verify the feasibility of this computer-based task, we conducted three experiments with different manipulations and groups of participants. We were interested in investigating if (1) the SDRST is sensitive enough to tap into cognitive differences brought by aging and dementia; (2) different experimental manipulations work successfully; (3) cortical brain activations seen in other WM tasks are also demonstrated here; and (4) non-human primates are able to answer the task. Performance (scores and response time) was better for young than older adults and higher for the latter when compared to Alzheimer's disease (AD) patients. All groups performed better with facial stimuli than with images of scenes and with emotional than with neutral stimuli. Electrophysiology data showed activation on prefrontal and frontal areas of scalp, theta band activity on the midline area, and gamma activity in left temporal area. There are all scalp regions known to be related to attention and WM. Besides those data, our sample of adult captive capuchin monkeys (Sapajus libidinosus) answered the task above chance level. Taken together, these results corroborate the reliability of this new computer-based SDRST as a measure of visuospatial WM in clinical and non-clinical populations as well as in non-human primates. Its tablet app allows the task to be administered in a wide range of settings, including hospitals, homes, schools, laboratories, universities, and research institutions.

  2. Computerized Spatial-Delayed Recognition Span Task: a specific tool to assess visuospatial working memory

    Directory of Open Access Journals (Sweden)

    Corina eSatler

    2015-04-01

    Full Text Available A new tablet device version (IOS platform of the Spatial Delayed Recognition Span Task (SDRST was developed with the aim of investigating visuospatial Working Memory (WM abilities based on touchscreen technology. This new WM testing application will be available to download for free in Apple Store app (SDRST app. In order to verify the feasibility of this computer-based task, we conducted three experiments with different manipulations and groups of participants. We were interested in investigating if (1 the SDRST is sensitive enough to tap into cognitive differences brought by ageing and dementia; (2 different experimental manipulations work successfully; (3 cortical brain activations seen in other WM tasks are also demonstrated here; and (4 non-human primates are able to answer the task. Performance (scores and response time was better for young than older adults and higher for the latter when compared to Alzheimer’s disease patients. All groups performed better with facial stimuli than with images of scenes and with emotional than with neutral stimuli. Electrophysiology data showed activation on prefrontal and frontal areas of scalp, theta band activity on the midline area, and gamma activity in left temporal area. There are all scalp regions known to be related to attention and WM. Besides those data, our sample of adult captive capuchin monkeys (Sapajus libidinosus answered the task above chance level. Taken together, these results corroborate the reliability of this new computer-based SDRST as a measure of visuospatial WM in clinical and non-clinical populations as well as in non-human primates. Its tablet app allows the task to be administered in a wide range of settings, including hospitals, homes, schools, laboratories, universities, and research institutions.

  3. Reaction time inconsistency in a spatial stroop task: age-related differences through childhood and adulthood.

    Science.gov (United States)

    Williams, Benjamin R; Strauss, Esther H; Hultsch, David F; Hunter, Michael A

    2007-07-01

    Age-related differences in inconsistency of reaction time (RT) across the life span were examined on a task with differing levels of demand on executive control. A total of 546 participants, aged 5 to 76 years, completed a spatial Stroop task that permitted observations under three conditions (congruent, incongruent, and neutral) according to the correspondence between the required response (based on stimulus direction) and stimulus location. An interference effect was observed across all ages. Analyses of neutral condition data replicated previous research demonstrating RT inconsistency follows a U-shaped developmental curve across the life span. The relationship between age and inconsistency, however, depended on condition: inconsistency in the congruent condition was higher than inconsistency in both the neutral and incongruent conditions across middle-aged groups. Reaction time inconsistency may reflect processing efficiency that is maximal in young adulthood and may also be sensitive to fluctuations in performance that reflect momentarily highly efficient responding.

  4. Projecting one’s own spatial bias onto others during a theory-of-mind task

    Science.gov (United States)

    Bio, Branden J.; Webb, Taylor W.; Graziano, Michael S. A.

    2018-01-01

    Many people show a left-right bias in visual processing. We measured spatial bias in neurotypical participants using a variant of the line bisection task. In the same participants, we measured performance in a social cognition task. This theory-of-mind task measured whether each participant had a processing-speed bias toward the right of, or left of, a cartoon agent about which the participant was thinking. Crucially, the cartoon was rotated such that what was left and right with respect to the cartoon was up and down with respect to the participant. Thus, a person’s own left-right bias could not align directly onto left and right with respect to the cartoon head. Performance on the two tasks was significantly correlated. People who had a natural bias toward processing their own left side of space were quicker to process how the cartoon might think about objects to the left side of its face, and likewise for a rightward bias. One possible interpretation of these results is that the act of processing one’s own personal space shares some of the same underlying mechanisms as the social cognitive act of reconstructing someone else’s processing of their space. PMID:29339513

  5. The Effects of 10 Hz Transcranial Alternating Current Stimulation on Audiovisual Task Switching

    Directory of Open Access Journals (Sweden)

    Michael S. Clayton

    2018-02-01

    Full Text Available Neural oscillations in the alpha band (7–13 Hz are commonly associated with disengagement of visual attention. However, recent studies have also associated alpha with processes of attentional control and stability. We addressed this issue in previous experiments by delivering transcranial alternating current stimulation at 10 Hz over posterior cortex during visual tasks (alpha tACS. As this stimulation can induce reliable increases in EEG alpha power, and given that performance on each of our visual tasks was negatively associated with alpha power, we assumed that alpha tACS would reliably impair visual performance. However, alpha tACS was instead found to prevent both deteriorations and improvements in visual performance that otherwise occurred during sham & 50 Hz tACS. Alpha tACS therefore appeared to exert a stabilizing effect on visual attention. This hypothesis was tested in the current, pre-registered experiment by delivering alpha tACS during a task that required rapid switching of attention between motion, color, and auditory subtasks. We assumed that, if alpha tACS stabilizes visual attention, this stimulation should make it harder for people to switch between visual tasks, but should have little influence on transitions between auditory and visual subtasks. However, in contrast to this prediction, we observed no evidence of impairments in visuovisual vs. audiovisual switching during alpha vs. control tACS. Instead, we observed a trend-level reduction in visuoauditory switching accuracy during alpha tACS. Post-hoc analyses showed no effects of alpha tACS in response time variability, diffusion model parameters, or on performance of repeat trials. EEG analyses also showed no effects of alpha tACS on endogenous or stimulus-evoked alpha power. We discuss possible explanations for these results, as well as their broader implications for current efforts to study the roles of neural oscillations in cognition using tACS.

  6. Evidence from a partial report task for forgetting in dynamic spatial memory.

    Science.gov (United States)

    Gugerty, L

    1998-09-01

    G. Sperling (1960) and others have investigated memory for briefly presented stimuli by using a partial versus whole report technique in which participants sometimes reported part of a stimulus array and sometimes reported all of it. For simple, static stimulus displays, the partial report technique showed that participants could recall most of the information in the stimulus array but that this information faded quickly when participants engaged in whole report recall. An experiment was conducted that applied the partial report method to a task involving complex displays of moving objects. In the experiment, 26 participants viewed cars in a low-fidelity driving simulator and then reported the locations of some or all of the cars in each scene. A statistically significant advantage was found for the partial report trials. This finding suggests that detailed spatial location information was forgotten from dynamic spatial memory over the 14 s that it took participants to recall whole report trials. The experiment results suggest better ways of measuring situation awareness. Partial report recall techniques may give a more accurate measure of people's momentary situation awareness than whole report techniques. Potential applications of this research include simulator-based measures of situation awareness ability that can be part of inexpensive test batteries to select people for real-time tasks (e.g., in a driver licensing battery) and to identify people who need additional training.

  7. Transfer of learning on a spatial memory task between the blind and sighted people.

    Science.gov (United States)

    Akpinar, Selcuk; Popović, Stevo; Kirazci, Sadettin

    2012-12-01

    The purpose of this study was to analyze the effect of two different types of feedback on a spatial memory task between the blind and blindfolded-sighted participants. Participants tried to estimate the predetermined distance by using their dominant hands. Both blind and blindfolded-sighted groups were randomly divided into two feedback subgroups as "100% frequency" and "10% bandwidth". The score of the participants was given verbally to the participants as knowledge of results (KR). The target distance was set as 60 cm. Sixty acquisition trials were performed in 4 sets each including 15 repetition afterwards immediate and delayed retention tests were undertaken. Moreover, 24 hours past the delayed retention test, the participants completed 15 no-KR trials as a transfer test (target distance was 30 cm). The results of the statistical analyses revealed no significant differences for both acquisition and retention tests. However, a significant difference was found at transfer test. 100% frequency blind group performed significantly less accurate than all other groups. As a result, it can be concluded that different types of feedback have similar effect on spatial memory task used in this study. However, types of feedback can change the performance of accuracy on transferring this skill among the blind.

  8. Alternating Dynamics of Segregation and Integration in Human EEG Functional Networks During Working-memory Task.

    Science.gov (United States)

    Zippo, Antonio G; Della Rosa, Pasquale A; Castiglioni, Isabella; Biella, Gabriele E M

    2018-02-10

    Brain functional networks show high variability in short time windows but mechanisms governing these transient dynamics remain unknown. In this work, we studied the temporal evolution of functional brain networks involved in a working memory (WM) task while recording high-density electroencephalography (EEG) in human normal subjects. We found that functional brain networks showed an initial phase characterized by an increase of the functional segregation index followed by a second phase where the functional segregation faded after the prevailing the functional integration. Notably, wrong trials were associated with different or disrupted sequences of the segregation-integration profiles and measures of network centrality and modularity were able to identify crucial aspects of the oscillatory network dynamics. Additionally, computational investigations further supported the experimental results. The brain functional organization may respond to the information processing demand of a WM task following a 2-step atomic scheme wherein segregation and integration alternately dominate the functional configurations. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  9. The effect of opponent type on human performance in a three-alternative choice task.

    Science.gov (United States)

    Lie, Celia; Baxter, Jennifer; Alsop, Brent

    2013-10-01

    Adult participants played computerised games of "Paper Scissors Rock". Participants in one group were told that they were playing against the computer, and those in the other group were told that they were playing against another participant in the adjacent room. The participant who won the most games would receive a $50 prize. For both groups however, the opponent's responses (paper, scissors, or rock) were generated by the computer, and the distribution of these responses was varied across four blocks of 126 trials. Results were analysed using the generalised matching law for the three possible pairs of alternatives (paper vs. scissors, paper vs. rock, and scissors vs. rock) across all participants in each group. Overall, significantly higher estimates of sensitivity to the distribution of opponent's responses were obtained from participants who were told their opponent was a computer compared to participants who were told their opponent was another participant. While adding to the existing literature showing that the generalised matching law is an adequate descriptor of human three-alternative choice behaviour, these findings show that external factors such as perceived opponent type can affect the efficacy of reinforcer contingencies on human behaviour. This suggests that generalising the results from tasks performed against a computer to real-life human-to-human interactions warrants some caution. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. A novel spatial Delayed Non-Match to Sample (DNMS) task in the Göttingen minipig

    DEFF Research Database (Denmark)

    Nielsen, Thomas Rune; Kornum, Birgitte Rahbek; Moustgaard, Anette

    2009-01-01

    required an average of 144 trials to reach criterion for learning the task, which is similar to macaque monkeys. We also found that pigs, in contrast to rats, do not have a natural tendency to alternate in their choices in the task. To evaluate the sensitivity to reduced memory function longer delay...

  11. Mineralocorticoid receptor stimulation effects on spatial memory in healthy young adults: A study using the virtual Morris Water Maze task.

    Science.gov (United States)

    Piber, Dominique; Schultebraucks, Katharina; Mueller, Sven C; Deuter, Christian Eric; Wingenfeld, Katja; Otte, Christian

    2016-12-01

    Stress hormones such as cortisol are known to influence a wide range of cognitive functions, including hippocampal based spatial memory. In the brain, cortisol acts via two different receptors: the glucocorticoid (GR) and the mineralocorticoid receptor (MR). As the MR has a high density in the hippocampus, we examined the effects of pharmacological MR stimulation on spatial memory. Eighty healthy participants (40 women, 40 men, mean age=23.9years±SD=3.3) completed the virtual Morris Water Maze (vMWM) task to test spatial encoding and spatial memory retrieval after receiving 0.4mg fludrocortisone, a MR agonist, or placebo. There was no effect of MR stimulation on spatial encoding during the vMWM task. However, participants who received fludrocortisone exhibited improved spatial memory retrieval performance. There was neither a main effect of sex nor a sex-by-treatment interaction. In young healthy participants, MR stimulation improved hippocampal based spatial memory retrieval in a virtual Morris Water Maze task. Our study not only confirms the importance of MR function in spatial memory, but suggests beneficial effects of acute MR stimulation on spatial memory retrieval in humans. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Very low birth weight piglets show improved cognitive performance in the spatial cognitive holeboard task

    Directory of Open Access Journals (Sweden)

    Alexandra eAntonides

    2015-02-01

    Full Text Available Low birth weight (LBW is common in humans and has been found to cause lasting cognitive and developmental deficits later in life. It is thought that the primary cause is intra-uterine growth restriction due to a shortage of oxygen and nutrients supply to the fetus. Pigs appear to be a good model animal to investigate long-term cognitive effects of LBW, as LBW is common in commercially farmed breeds of pigs. Moreover, pigs are developmentally similar to humans and can be trained to perform complex tasks. In this study, we trained ten very low birth weight (vLBW piglets and their ten normal birth weight (NBW siblings in a spatial cognitive holeboard task in order to investigate long-term cognitive effects of LBW. In this task, four out of sixteen holes contain a hidden food reward, which allows measuring working memory (short-term and reference memory (long-term in parallel. Piglets were trained for 46-54 trials during the acquisition phase, followed by a 20-trial reversal phase in which a different set of four holes was baited. Both groups acquired the task and improved their performance over time. A mixed model repeated measures ANOVA revealed that vLBW piglets showed a better reference memory performance than NBW piglets in both the acquisition and reversal phase. Additionally, the vLBW piglets fell back less in working memory scores than the NBW animals when switched to the reversal phase. These findings are contrary to findings in humans. Moreover, vLBW pigs had lower hair cortisol concentrations than NBW pigs in flank hair at 12 weeks of age. These results could indicate that restricted intra-uterine growth causes compensatory mechanisms to arise in early development that result in beneficial effects for vLBW piglets, increasing their low survival chances in early-life competition.

  13. Very low birth weight piglets show improved cognitive performance in the spatial cognitive holeboard task.

    Science.gov (United States)

    Antonides, Alexandra; Schoonderwoerd, Anne C; Nordquist, Rebecca E; van der Staay, Franz Josef

    2015-01-01

    Low birth weight (LBW) is common in humans and has been found to cause lasting cognitive and developmental deficits later in life. It is thought that the primary cause is intra-uterine growth restriction (IUGR) due to a shortage of oxygen and supply of nutrients to the fetus. Pigs appear to be a good model animal to investigate long-term cognitive effects of LBW, as LBW is common in commercially farmed breeds of pigs. Moreover, pigs are developmentally similar to humans and can be trained to perform complex tasks. In this study, we trained ten very low birth weight (vLBW) piglets and their ten normal birth weight (NBW) siblings in a spatial cognitive holeboard task in order to investigate long-term cognitive effects of LBW. In this task, four out of sixteen holes contain a hidden food reward, which allows measuring working memory (WM) (short-term memory) and reference memory (RM) (long-term memory) in parallel. Piglets were trained for 46-54 trials during the acquisition phase, followed by a 20-trial reversal phase in which a different set of four holes was baited. Both groups acquired the task and improved their performance over time. A mixed model repeated measures ANOVA revealed that vLBW piglets showed better RM performance than NBW piglets in both the acquisition and reversal phase. Additionally, WM scores in the vLBW were less disrupted than in the NBW animals when switched to the reversal phase. These findings are contrary to findings in humans. Moreover, vLBW pigs had lower hair cortisol concentrations (HCCs) than NBW pigs in flank hair at 12 weeks of age. These results could indicate that restricted intra-uterine growth causes compensatory mechanisms to arise in early development that result in beneficial effects for vLBW piglets, increasing their low survival chances in early-life competition.

  14. Planning Support Systems (PSS-Based Spatial Plan Alternatives and Environmental Assessment

    Directory of Open Access Journals (Sweden)

    Hee-Sun Choi

    2016-03-01

    Full Text Available Spatial planning is at the core of national land and urban development. Many countries and cities seek sustainable development through various means such as coordinated environmental planning, environmental assessment, and internalization of environmental analysis and planning. A Planning Support System (PSS is a GIS (Geographic Information System-based, spatial decision-making support system that incorporates a variety of theories and pertinent models. This study adopted the “What if?” model to design an alternative spatial plan that includes generation of predictive scenarios and is relatively easy to use. In the cities studied, we identified a total of six scenarios based on the main drivers of development—namely, population and spatial policies. Subsequently, we assessed the alternatives for their environmental impact, preparing sensitivity maps for each major environmental issue in the target area (natural ecosystem, air and microclimate, natural disasters. One projected advantage of the “What if?” model is that its digital visualization of proposed plans may improve public awareness and involvement. Furthermore, the tool is expected to be highly useful in ensuring the objectivity of quantitative analyses. However, it is necessary to develop a PSS that is both standardized and tailored to the particular needs of each area. Finally, the development of an e-governance system will be beneficial in ensuring public access to the decision making process.

  15. The effects of age and workload on 3D spatial attention in dual-task driving.

    Science.gov (United States)

    Pierce, Russell S; Andersen, George J

    2014-06-01

    In the present study we assessed whether the limits in visual-spatial attention associated with aging affect the spatial extent of attention in depth during driving performance. Drivers in the present study performed a car-following and light-detection task. To assess the extent of visual-spatial attention, we compared reaction times and accuracy to light change targets that varied in horizontal position and depth location. In addition, because workload has been identified as a factor that can change the horizontal and vertical extent of attention, we tested whether variability of the lead car speed influenced the extent of spatial attention for younger or older drivers. For younger drivers, reaction time (RT) to light-change targets varied as a function of distance and horizontal position. For older drivers RT varied only as a function of distance. There was a distance by horizontal position interaction for younger drivers but not for older drivers. Specifically, there was no effect of horizontal position at any given level of depth for older drivers. However, for younger drivers there was an effect of horizontal position for targets further in depth but not for targets nearer in depth. With regards to workload, we found no statistically reliable evidence that variability of the lead car speed had an effect on the spatial extent of attention for younger or older drivers. In a control experiment, we examined the effects of depth on light detection when the projected size and position of the targets was constant. Consistent with our previous results, we found that drivers' reaction time to light-change targets varied as a function of distance even when 2D position and size were controlled. Given that depth is an important dimension in driving performance, an important issue for assessing driving safety is to consider the limits of attention in the depth dimension. Therefore, we suggest that future research should consider the importance of depth as a dimension of

  16. Lucky numbers: spatial neglect affects physical, but not representational, choices in a lotto task.

    Science.gov (United States)

    Loetscher, Tobias; Nicholls, Michael E R; Towse, John N; Bradshaw, John L; Brugger, Peter

    2010-05-01

    Spatial neglect can be characterized by a "magnetic attraction" towards the right side of a visual stimulus array and a selection of stimuli from that hemispace. This study examined whether these distinctive characteristics in visuo-motor space are also evident in representational number space. Given that numbers are thought to be represented along a left-to-right oriented mental number line, an affinity for the spontaneous selection of larger numbers was anticipated for neglect patients. Contrary to this expectation, neglect patients (n=20) picked a similar range of numbers compared to controls (n=17) when generating a number between 1000 and 10,000 and when playing an imaginary lottery game. There was, however, a positive correlation between the biases for the imaginary lottery, number generation and a number bisection task - demonstrating that exploration asymmetries along the mental number line are consistent within individuals across tasks. Some of the patients selected smaller numbers in all of these tasks, confirming reports of dissociations between physical and numerical-representational forms of neglect. Conversely, only four (20%) of the patients could reliably be classified as demonstrating a neglect in number space. When filling out a physical lottery ticket, the neglect patients showed the expected bias towards picking numbers placed on the right-hand side of the ticket. These results demonstrate that the magnetic attraction towards the right side of mental representations is rather weak and that representational forms of neglect only occasionally co-exist with neglect in physical space. Copyright 2009 Elsevier Srl. All rights reserved.

  17. Dizocilpine (MK-801) impairs learning in the active place avoidance task but has no effect on the performance during task/context alternation

    Czech Academy of Sciences Publication Activity Database

    Vojtěchová, Iveta; Petrásek, Tomáš; Hatalová, Hana; Pištíková, Adéla; Valeš, Karel; Stuchlík, Aleš

    2016-01-01

    Roč. 305, May 15 (2016), s. 247-257 ISSN 0166-4328 R&D Projects: GA ČR(CZ) GA14-03627S Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M200111204 Institutional support: RVO:67985823 Keywords : task alternation * context alternation * active place avoidance * Morris water maze * Dizocilpine * schizophrenia Subject RIV: FH - Neurology Impact factor: 3.002, year: 2016

  18. Effects of caloric restriction on learning and recovery of a spatial task in rats exposed to acute stress

    Directory of Open Access Journals (Sweden)

    Lamprea Rodríguez, Marisol

    2009-06-01

    Full Text Available The purpose of the present study was to describe the effects of caloric restriction on spatial learning and recovery in the Barnes maze in animals experimentally stressed before recovery of the spatial task. Male Wistar rats were exposed for two months to one of two conditions: ad libitum (AL or intermittent fasting (IF. Both groups were exposed then to an experimental form of acute stress, induced by movement restriction for 4 hours. IF subjects had better performance in learning tasks during the acquisition trials but required more time to complete the task after the stressor was applied. These results are discussed in light of previous data reported in the literature emphasizing differences in the instruments used to evaluate spatial learning and its interaction with experimentally induced stress.

  19. A Virtual Reality Task Based on Animal Research - Spatial Learning and Memory in Patients after the First Episode of Schizophrenia

    Directory of Open Access Journals (Sweden)

    Iveta eFajnerova

    2014-05-01

    Full Text Available Objective: Cognitive deficit is considered to be a characteristic feature of schizophrenia disorder. A similar cognitive dysfunction was demonstrated in animal models of schizophrenia. However, the poor comparability of methods used to assess cognition in animals and humans could be responsible for low predictive validity of current animal models. In order to assess spatial abilities in schizophrenia and compare our results with the data obtained in animal models we designed a virtual analogue of the Morris water maze (MWM, the virtual Four Goals Navigation (vFGN task.Method: Twenty-nine patients after the first psychotic episode with schizophrenia symptoms and a matched group of healthy volunteers performed the vFGN task. They were required to find and remember four hidden goal positions in an enclosed virtual arena. The task consisted of two parts. The Reference memory (RM session with a stable goal position was designed to test spatial learning. The Delayed-matching-to-place (DMP session presented a modified working memory protocol designed to test the ability to remember a sequence of three hidden goal positions.Results: Data obtained in the RM session show impaired spatial learning in schizophrenia patients compared to healthy controls in pointing and navigation accuracy. The DMP session showed impaired spatial memory in schizophrenia during the recall of spatial sequence and similar deficit in spatial bias in probe trials. The pointing accuracy and the quadrant preference showed higher sensitivity toward the cognitive deficit than the navigation accuracy. Direct navigation to the goal was affected by sex and age of the tested subjects. Age affected spatial performance only in healthy controls. Conclusions: Despite some limitations of the study, our results correspond well to previous studies in animal models of schizophrenia and support the decline of spatial cognition in schizophrenia, indicating the usefulness of the vFGN task in

  20. Progressive impairment of directional and spatially precise trajectories by TgF344-AD Rats in the Morris Water Task

    OpenAIRE

    Thompson, Shannon; Harvey, Ryan; Clark, Benjamin; Drake, Emma; Berkowitz, Laura

    2018-01-01

    Spatial navigation is impaired in early stages of Alzheimers disease (AD), and may be a defining behavioral marker of preclinical AD. Nevertheless, limitations of diagnostic criteria for AD and within animal models of AD make characterization of preclinical AD difficult. A new rat model (TgF344-AD) of AD overcomes many of these limitations, though spatial navigation has not been comprehensively assessed. Using the hidden and cued platform variants of the Morris water task, a longitudinal asse...

  1. The right look for the job: decoding cognitive processes involved in the task from spatial eye-movement patterns.

    Science.gov (United States)

    Król, Magdalena Ewa; Król, Michał

    2018-02-20

    The aim of the study was not only to demonstrate whether eye-movement-based task decoding was possible but also to investigate whether eye-movement patterns can be used to identify cognitive processes behind the tasks. We compared eye-movement patterns elicited under different task conditions, with tasks differing systematically with regard to the types of cognitive processes involved in solving them. We used four tasks, differing along two dimensions: spatial (global vs. local) processing (Navon, Cognit Psychol, 9(3):353-383 1977) and semantic (deep vs. shallow) processing (Craik and Lockhart, J Verbal Learn Verbal Behav, 11(6):671-684 1972). We used eye-movement patterns obtained from two time periods: fixation cross preceding the target stimulus and the target stimulus. We found significant effects of both spatial and semantic processing, but in case of the latter, the effect might be an artefact of insufficient task control. We found above chance task classification accuracy for both time periods: 51.4% for the period of stimulus presentation and 34.8% for the period of fixation cross presentation. Therefore, we show that task can be to some extent decoded from the preparatory eye-movements before the stimulus is displayed. This suggests that anticipatory eye-movements reflect the visual scanning strategy employed for the task at hand. Finally, this study also demonstrates that decoding is possible even from very scant eye-movement data similar to Coco and Keller, J Vis 14(3):11-11 (2014). This means that task decoding is not limited to tasks that naturally take longer to perform and yield multi-second eye-movement recordings.

  2. Low Birth Weight Impairs Acquisition of Spatial Memory Task in Pigs

    Directory of Open Access Journals (Sweden)

    Sanne Roelofs

    2018-06-01

    Full Text Available In commercial pig farming, an increasing number of low birth weight (LBW piglets are born, due to selection for large litter sizes. While LBW piglets have a higher risk of pre-weaning mortality, a considerable number of these piglets survive to slaughter age. In humans, LBW is a risk factor for long-term cognitive impairments. In pigs, studies examining the post-weaning effects of LBW on cognition have reported contradictory results. Therefore, the current study aimed to assess the effects of LBW on cognitive development in pigs using an improved study design, by (1 testing a larger sample size than previous studies, (2 assessing acute and chronic stress responses to account for a potential altered stress response in LBW pigs, and (3 testing both female and male pigs to account for potential confounding effects of sex. Learning and memory of 20 LBW pigs and 20 normal birth weight (NBW pigs, both groups consisting of 10 females and 10 males, were compared using a spatial holeboard task. In this task, pigs had to learn and remember the locations of hidden food rewards. After a pig had successfully acquired the task, it was presented with two successive reversal phases during which it was presented with a new configuration of reward locations. The holeboard allows for simultaneous assessment of working and reference memory, as well as measures of motivation, exploration, and behavioral flexibility. Mixed model ANOVAs revealed a transiently impaired reference memory performance of LBW pigs, implying they had more difficulty learning their reward configuration in the holeboard. Also, LBW piglets showed increased pre-weaning hair cortisol concentrations compared to their NBW siblings. No other effects of LBW were found. Sex had no direct or interaction effects on any measures of holeboard performance or stress. It is possible that the enriched housing conditions applied during our study had an ameliorating effect on our pigs' cognitive development

  3. Alternative methods for dispoal of low-level radioactive wastes. Task 1. Description of methods and assessment of criteria

    International Nuclear Information System (INIS)

    Bennett, R.D.; Miller, W.O.; Warriner, J.B.; Malone, P.G.; McAneny, C.C.

    1984-04-01

    The study reported herein contains the results of Task 1 of a four-task study entitled Criteria for Evaluating Engineered Facilities. The overall objective of this study is to ensure that the criteria needed to evaluate five alternative low-level radioactive waste (LLW) disposal methods are available to the Nuclear Regulatory Commission (NRC) and the Agreement States. The alternative methods considered are belowground vaults, aboveground vaults, earth mounded concrete bunkers, mined cavities, and augered holes. Each of these alternatives is either being used by other countries for low-level radioactive waste (LLW) disposal or is being considered by other countries or US agencies. In this report the performance requirements are listed, each alternative is described, the experience gained with its use is discussed, and the performance capabilities of each method are addressed. Next, the existing 10 CFR Part 61 Subpart D criteria with respect to paragraphs 61.50 through 61.53, pertaining to site suitability, design, operations and closure, and monitoring are assessed for applicability to evaluation of each alternative. Preliminary conclusions and recommendations are offered on each method's suitability as an LLW disposal alternative, the applicability of the criteria, and the need for supplemental or modified criteria

  4. High-sucrose diets in male rats disrupt aspects of decision making tasks, motivation and spatial memory, but not impulsivity measured by operant delay-discounting.

    Science.gov (United States)

    Wong, Alanna; Dogra, Vimi R; Reichelt, Amy C

    2017-06-01

    Excessive consumption of sugar sweetened drinks is proposed to produce functional changes in the hippocampus and prefrontal cortex, leading to perturbations in behavioural control. Impairments in behavioural control have been observed in obese people on tasks that involve making choices, including delay-discounting, indicative of increased impulsivity. In this study we examined the impact of 2h daily access to 10% sucrose (or no sucrose in controls) in young male rats on behavioural tasks reliant on hippocampal function including delay-discounting, T-maze forced choice alternation and place recognition memory, as well as progressive ratio to measure motivation. We observed deficits in place recognition memory and T-maze forced choice alternation, indicative of hippocampal deficits in rats with a history of sucrose consumption. Moreover, rats with a history of sucrose consumption were less motivated to lever press for rewards on a progressive ratio schedule. However, rats with a history of sucrose consumption performed equally to control animals during the delay-discounting task, suggesting that they discounted for reward size over a delay in a manner comparable to control animals. These findings indicate that high-sucrose diets impact on spatial and working memory processes, but do not induce impulsive-like choice behaviours in rats, suggesting that unhealthy diet choices may not influence this aspect of decision-making behaviour. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Beyond Conceptual Knowledge: The Impact of Children’s Theory-of-Mind on Dyadic Spatial Tasks

    Science.gov (United States)

    Viana, Karine M. P.; Zambrana, Imac M.; Karevold, Evalill B.; Pons, Francisco

    2016-01-01

    Recent studies show that Theory of Mind (ToM) has implications for children’s social competences and psychological well-being. Nevertheless, although it is well documented that children overall take advantage when they have to resolve cognitive problems together with a partner, whether individual difference in ToM is one of the mechanisms that could explain cognitive performances produced in social interaction has received little attention. This study examines to what extent ToM explains children’s spatial performances in a dyadic situation. The sample includes 66 boys and girls between the ages of 5–9 years, who were tested for their ToM and for their competence to resolve a Spatial task involving mental rotation and spatial perspective taking, first individually and then in a dyadic condition. Results showed, in accordance with previous research, that children performed better on the Spatial task when they resolved it with a partner. Specifically, children’s ToM was a better predictor of their spatial performances in the dyadic condition than their age, gender, and spatial performances in the individual setting. The findings are discussed in terms of the relation between having a conceptual understanding of the mind and the practical implications of this knowledge for cognitive performances in social interaction regarding mental rotation and spatial perspective taking. PMID:27812344

  6. Study of target and non-target interplay in spatial attention task.

    Science.gov (United States)

    Sweeti; Joshi, Deepak; Panigrahi, B K; Anand, Sneh; Santhosh, Jayasree

    2018-02-01

    Selective visual attention is the ability to selectively pay attention to the targets while inhibiting the distractors. This paper aims to study the targets and non-targets interplay in spatial attention task while subject attends to the target object present in one visual hemifield and ignores the distractor present in another visual hemifield. This paper performs the averaged evoked response potential (ERP) analysis and time-frequency analysis. ERP analysis agrees to the left hemisphere superiority over late potentials for the targets present in right visual hemifield. Time-frequency analysis performed suggests two parameters i.e. event-related spectral perturbation (ERSP) and inter-trial coherence (ITC). These parameters show the same properties for the target present in either of the visual hemifields but show the difference while comparing the activity corresponding to the targets and non-targets. In this way, this study helps to visualise the difference between targets present in the left and right visual hemifields and, also the targets and non-targets present in the left and right visual hemifields. These results could be utilised to monitor subjects' performance in brain-computer interface (BCI) and neurorehabilitation.

  7. Daily Access to Sucrose Impairs Aspects of Spatial Memory Tasks Reliant on Pattern Separation and Neural Proliferation in Rats

    Science.gov (United States)

    Reichelt, Amy C.; Morris, Margaret J.; Westbrook, Reginald Frederick

    2016-01-01

    High sugar diets reduce hippocampal neurogenesis, which is required for minimizing interference between memories, a process that involves "pattern separation." We provided rats with 2 h daily access to a sucrose solution for 28 d and assessed their performance on a spatial memory task. Sucrose consuming rats discriminated between objects…

  8. Beyond time and space: The effect of a lateralized sustained attention task and brain stimulation on spatial and selective attention.

    Science.gov (United States)

    Shalev, Nir; De Wandel, Linde; Dockree, Paul; Demeyere, Nele; Chechlacz, Magdalena

    2017-10-03

    The Theory of Visual Attention (TVA) provides a mathematical formalisation of the "biased competition" account of visual attention. Applying this model to individual performance in a free recall task allows the estimation of 5 independent attentional parameters: visual short-term memory (VSTM) capacity, speed of information processing, perceptual threshold of visual detection; attentional weights representing spatial distribution of attention (spatial bias), and the top-down selectivity index. While the TVA focuses on selection in space, complementary accounts of attention describe how attention is maintained over time, and how temporal processes interact with selection. A growing body of evidence indicates that different facets of attention interact and share common neural substrates. The aim of the current study was to modulate a spatial attentional bias via transfer effects, based on a mechanistic understanding of the interplay between spatial, selective and temporal aspects of attention. Specifically, we examined here: (i) whether a single administration of a lateralized sustained attention task could prime spatial orienting and lead to transferable changes in attentional weights (assigned to the left vs right hemi-field) and/or other attentional parameters assessed within the framework of TVA (Experiment 1); (ii) whether the effects of such spatial-priming on TVA parameters could be further enhanced by bi-parietal high frequency transcranial random noise stimulation (tRNS) (Experiment 2). Our results demonstrate that spatial attentional bias, as assessed within the TVA framework, was primed by sustaining attention towards the right hemi-field, but this spatial-priming effect did not occur when sustaining attention towards the left. Furthermore, we show that bi-parietal high-frequency tRNS combined with the rightward spatial-priming resulted in an increased attentional selectivity. To conclude, we present a novel, theory-driven method for attentional modulation

  9. Characterizing Spatial Dynamics of Bifurcation to Alternans in Isolated Whole Rabbit Hearts Based on Alternate Pacing

    Directory of Open Access Journals (Sweden)

    Kanchan Kulkarni

    2015-01-01

    Full Text Available Sudden cardiac death instigated by ventricular fibrillation (VF is the largest cause of natural death in the USA. Alternans, a beat-to-beat alternation in the action potential duration, has been implicated as being proarrhythmic. The onset of alternans is mediated via a bifurcation, which may occur through either a smooth or a border-collision mechanism. The objective of this study was to characterize the mechanism of bifurcation to alternans based on experiments in isolated whole rabbit hearts. High resolution optical mapping was performed and the electrical activity was recorded from the left ventricle (LV epicardial surface of the heart. Each heart was paced using an “alternate pacing protocol,” where the basic cycle length (BCL was alternatively perturbed by ±δ. Local onset of alternans in the heart, BCLstart, was measured in the absence of perturbations (δ=0 and was defined as the BCL at which 10% of LV exhibited alternans. The influences of perturbation size were investigated at two BCLs: one prior to BCLstart (BCLprior=BCLstart+20 ms and one preceding BCLprior (BCLfar=BCLstart+40 ms. Our results demonstrate significant spatial correlation of the region exhibiting alternans with smooth bifurcation characteristics, indicating that transition to alternans in isolated rabbit hearts occurs predominantly through smooth bifurcation.

  10. Evaluation of the effectiveness and feasibility of the Waste Isolation Pilot Plant engineered alternatives: Final report of the Engineered Alternatives Task Force

    International Nuclear Information System (INIS)

    1991-07-01

    The Engineered Alternatives Task Force (EATF) was established by the United States Department of Energy (DOE) WIPP Project Office (WPO) in September 1989 (Hunt, A., 1990), to evaluate the relative effectiveness and feasibility of implementation of selected design enhancements (referred to as ''engineered alternatives'') for the Waste Isolation Pilot Plant (WIPP). These enhancements consist of modifications of existing waste forms and/or the WIPP facility, and other design variations such as passive marker systems. The purpose of this report is to summarize the methodologies and results of evaluation of the effectiveness of selected engineered alternatives relative to the existing repository design, and to discuss the feasibility of implementing these alternatives with respect to availability of technology, cost, schedule, and regulatory concerns. The EATF has concluded that a number of engineered alternatives could be implemented to improve repository performance if WIPP performance assessment determines that either gas generation or human intrusion presents a problem in demonstrating compliance. Within waste treatment, Level 3 treatments are the most effective in addressing multiple performance parameters, but tend to be the most expensive, the most difficult and time-consuming to implement, and have the greatest regulatory requirements. Level 2 treatments are less expensive, faster, require less extensive permitting, and utilize off- the-shelf technology, but are less effective in addressing multiple performance parameters. Depending upon the performance parameter, Level 1 alternatives such as alternative backfills, alternative waste containers, or modified repository design should be thoroughly evaluated and eliminated before any decision is made to treat the waste. The present uncertainty in the degree to which the baseline WIPP design complies with 40 CFR Part 191 and 40 CFR Part 268 precludes specific recommendations at this time. 130 refs., 21 figs., 37 tabs

  11. Integrated cross-domain object storage in working memory: evidence from a verbal-spatial memory task.

    Science.gov (United States)

    Morey, Candice C

    2009-11-01

    Working-memory theories often include domain-specific verbal and visual stores (e.g., the phonological and visuospatial buffers of Baddeley, 1986), and some also posit more general stores thought to be capable of holding verbal or visuospatial materials (Baddeley, 2000; Cowan, 2005). However, it is currently unclear which type of store is primarily responsible for maintaining objects that include components from multiple domains. In these studies, a spatial array of letters was followed by a single probe identical to an item in the array or differing systematically in spatial location, letter identity, or their combination. Concurrent verbal rehearsal suppression impaired memory in each of these trial types in a task that required participants to remember verbal-spatial binding, but did not impair memory for spatial locations if the task did not require verbal-spatial binding for a correct response. Thus, spatial information might be stored differently when it must be bound to verbal information. This suggests that a cross-domain store such as the episodic buffer of Baddeley (2000) or the focus of attention of Cowan (2001) might be used for integrated object storage, rather than the maintenance of associations between features stored in separate domain-specific buffers.

  12. Neural mechanisms underlying conflict monitoring over risky decision alternatives: evidence from ERP in a Go/Nogo task.

    Science.gov (United States)

    Wang, Shuzhen; Hui, Ning; Zhou, Xinsheng; He, Kaifeng; Yu, Yuanyuan; Shuai, Jing

    2014-09-01

    This study assessed conflict monitoring during presentation of risky decision alternatives, as indexed by the Nogo-N2, Nogo-P3, N2d and P3d event-related potentials (ERP). Decision-makers were tested on a Go/Nogo gambling task in which gain/loss outcomes as well as stimulus type (Go/Nogo) were equiprobable. Frontal-central Nogo-N2 and Nogo-P3 did not significantly differ across risky decision alternatives, whereas N2d and P3d amplitudes were more sensitive to the nature of risky decision alternatives. Frontal-central N2d was moderated by the magnitude of alternatives, with N2d amplitude greater for large than small alternatives, a result that suggests a greater degree of conflict monitoring for the former. Central P3d was associated with alternative valence, such that P3d amplitude was greater for loss than gain valences, again suggestive of more conflict monitoring for the former. The N2d and P3d potentials in risky decision alternatives are discussed in terms of the functional significance of the N2/P3 complex.

  13. Object-based selection from spatially-invariant representations: evidence from a feature-report task.

    Science.gov (United States)

    Matsukura, Michi; Vecera, Shaun P

    2011-02-01

    Attention selects objects as well as locations. When attention selects an object's features, observers identify two features from a single object more accurately than two features from two different objects (object-based effect of attention; e.g., Duncan, Journal of Experimental Psychology: General, 113, 501-517, 1984). Several studies have demonstrated that object-based attention can operate at a late visual processing stage that is independent of objects' spatial information (Awh, Dhaliwal, Christensen, & Matsukura, Psychological Science, 12, 329-334, 2001; Matsukura & Vecera, Psychonomic Bulletin & Review, 16, 529-536, 2009; Vecera, Journal of Experimental Psychology: General, 126, 14-18, 1997; Vecera & Farah, Journal of Experimental Psychology: General, 123, 146-160, 1994). In the present study, we asked two questions regarding this late object-based selection mechanism. In Part I, we investigated how observers' foreknowledge of to-be-reported features allows attention to select objects, as opposed to individual features. Using a feature-report task, a significant object-based effect was observed when to-be-reported features were known in advance but not when this advance knowledge was absent. In Part II, we examined what drives attention to select objects rather than individual features in the absence of observers' foreknowledge of to-be-reported features. Results suggested that, when there was no opportunity for observers to direct their attention to objects that possess to-be-reported features at the time of stimulus presentation, these stimuli must retain strong perceptual cues to establish themselves as separate objects.

  14. Society of Gynecologic Oncology Future of Physician Payment Reform Task Force report: The Endometrial Cancer Alternative Payment Model (ECAP).

    Science.gov (United States)

    Ko, Emily M; Havrilesky, Laura J; Alvarez, Ronald D; Zivanovic, Oliver; Boyd, Leslie R; Jewell, Elizabeth L; Timmins, Patrick F; Gibb, Randall S; Jhingran, Anuja; Cohn, David E; Dowdy, Sean C; Powell, Matthew A; Chalas, Eva; Huang, Yongmei; Rathbun, Jill; Wright, Jason D

    2018-05-01

    Health care in the United States is in the midst of a significant transformation from a "fee for service" to a "fee for value" based model. The Medicare Access and CHIP Reauthorization Act of 2015 has only accelerated this transition. Anticipating these reforms, the Society of Gynecologic Oncology developed the Future of Physician Payment Reform Task Force (PPRTF) in 2015 to develop strategies to ensure fair value based reimbursement policies for gynecologic cancer care. The PPRTF elected as a first task to develop an Alternative Payment Model for thesurgical management of low risk endometrial cancer. The history, rationale, and conceptual framework for the development of an Endometrial Cancer Alternative Payment Model are described in this white paper, as well as directions forfuture efforts. Copyright © 2018 Elsevier Inc. All rights reserved.

  15. Hypergraph+: An Improved Hypergraph-Based Task-Scheduling Algorithm for Massive Spatial Data Processing on Master-Slave Platforms

    Directory of Open Access Journals (Sweden)

    Bo Cheng

    2016-08-01

    Full Text Available Spatial data processing often requires massive datasets, and the task/data scheduling efficiency of these applications has an impact on the overall processing performance. Among the existing scheduling strategies, hypergraph-based algorithms capture the data sharing pattern in a global way and significantly reduce total communication volume. Due to heterogeneous processing platforms, however, single hypergraph partitioning for later scheduling may be not optimal. Moreover, these scheduling algorithms neglect the overlap between task execution and data transfer that could further decrease execution time. In order to address these problems, an extended hypergraph-based task-scheduling algorithm, named Hypergraph+, is proposed for massive spatial data processing. Hypergraph+ improves upon current hypergraph scheduling algorithms in two ways: (1 It takes platform heterogeneity into consideration offering a metric function to evaluate the partitioning quality in order to derive the best task/file schedule; and (2 It can maximize the overlap between communication and computation. The GridSim toolkit was used to evaluate Hypergraph+ in an IDW spatial interpolation application on heterogeneous master-slave platforms. Experiments illustrate that the proposed Hypergraph+ algorithm achieves on average a 43% smaller makespan than the original hypergraph scheduling algorithm but still preserves high scheduling efficiency.

  16. Persistent spatial information in the FEF during object-based short-term memory does not contribute to task performance.

    Science.gov (United States)

    Clark, Kelsey L; Noudoost, Behrad; Moore, Tirin

    2014-06-01

    We previously reported the existence of a persistent spatial signal in the FEF during object-based STM. This persistent activity reflected the location at which the sample appeared, irrespective of the location of upcoming targets. We hypothesized that such a spatial signal could be used to maintain or enhance object-selective memory activity elsewhere in cortex, analogous to the role of a spatial signal during attention. Here, we inactivated a portion of the FEF with GABAa agonist muscimol to test whether the observed activity contributes to object memory performance. We found that, although RTs were slowed for saccades into the inactivated portion of retinotopic space, performance for samples appearing in that region was unimpaired. This contrasts with the devastating effects of the same FEF inactivation on purely spatial working memory, as assessed with the memory-guided saccade task. Thus, in a task in which a significant fraction of FEF neurons displayed persistent, sample location-based activity, disrupting this activity had no impact on task performance.

  17. The Effect of Two-dimensional and Stereoscopic Presentation on Middle School Students' Performance of Spatial Cognition Tasks

    Science.gov (United States)

    Price, Aaron; Lee, Hee-Sun

    2010-02-01

    We investigated whether and how student performance on three types of spatial cognition tasks differs when worked with two-dimensional or stereoscopic representations. We recruited nineteen middle school students visiting a planetarium in a large Midwestern American city and analyzed their performance on a series of spatial cognition tasks in terms of response accuracy and task completion time. Results show that response accuracy did not differ between the two types of representations while task completion time was significantly greater with the stereoscopic representations. The completion time increased as the number of mental manipulations of 3D objects increased in the tasks. Post-interviews provide evidence that some students continued to think of stereoscopic representations as two-dimensional. Based on cognitive load and cue theories, we interpret that, in the absence of pictorial depth cues, students may need more time to be familiar with stereoscopic representations for optimal performance. In light of these results, we discuss potential uses of stereoscopic representations for science learning.

  18. Learning spatial orientation tasks in the radial-maze and structural variation in the hippocampus in inbred mice

    Directory of Open Access Journals (Sweden)

    Schwegler Herbert

    2005-04-01

    Full Text Available Abstract In the present paper we review a series of experiments showing that heritable variations in the size of the hippocampal intra- and infrapyramidal mossy fiber (IIPMF terminal fields correlate with performance in spatial, but not non-spatial radial-maze tasks. Experimental manipulation of the size of this projection by means of early postnatal hyperthyroidism produces the effects predicted from the correlations obtained with inbred mouse strains. Although the physiological mechanisms behind these correlations are unknown as yet, several lines of evidence indicate that these correlations are causal.

  19. Walking and non-walking space in an equivalent virtual reality task: Sexual dimorphism and aging decline of spatial abilities.

    Science.gov (United States)

    Tascón, Laura; Castillo, Joaquín; León, Irene; Cimadevilla, José Manuel

    2018-07-16

    Spatial memory enables us to locate places and objects in space, to determine our position and manage spatial relationships in our environment. Our operations are displayed in a space that sometimes is inaccessible. In this case, the impossibility of movement within the context forces individuals to rely on the information gathered from limited viewpoints. This study investigates the use of walking and non-walking spaces using two equivalent virtual reality tasks in which displacement is only permitted in one of them. One hundred and fifty participants were divided into three age groups: 50-59, 60-69 and 70-79 year-old subjects. The starting position changed pseudo-randomly and two difficulty levels were set, with one and three positions to be found. Results provided evidence for 70-79 year-old people impairment of their spatial abilities compared with 50-59 and 60-69 year-old groups. In both difficulty conditions, participants made more errors in the non-walking space than in the walking space. All participants showed an improvement in the last trials of the task. Moreover, sexual dimorphism was registered in the high level of difficulty, in which men outperformed women. This study supports the idea that aging impairs the organization of spatial representations of the environment, and that this aspect is more noticeable in conditions where displacement is limited. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Learning and inference using complex generative models in a spatial localization task.

    Science.gov (United States)

    Bejjanki, Vikranth R; Knill, David C; Aslin, Richard N

    2016-01-01

    A large body of research has established that, under relatively simple task conditions, human observers integrate uncertain sensory information with learned prior knowledge in an approximately Bayes-optimal manner. However, in many natural tasks, observers must perform this sensory-plus-prior integration when the underlying generative model of the environment consists of multiple causes. Here we ask if the Bayes-optimal integration seen with simple tasks also applies to such natural tasks when the generative model is more complex, or whether observers rely instead on a less efficient set of heuristics that approximate ideal performance. Participants localized a "hidden" target whose position on a touch screen was sampled from a location-contingent bimodal generative model with different variances around each mode. Over repeated exposure to this task, participants learned the a priori locations of the target (i.e., the bimodal generative model), and integrated this learned knowledge with uncertain sensory information on a trial-by-trial basis in a manner consistent with the predictions of Bayes-optimal behavior. In particular, participants rapidly learned the locations of the two modes of the generative model, but the relative variances of the modes were learned much more slowly. Taken together, our results suggest that human performance in a more complex localization task, which requires the integration of sensory information with learned knowledge of a bimodal generative model, is consistent with the predictions of Bayes-optimal behavior, but involves a much longer time-course than in simpler tasks.

  1. Comparison of marine spatial planning methods in Madagascar demonstrates value of alternative approaches.

    Directory of Open Access Journals (Sweden)

    Thomas F Allnutt

    Full Text Available The Government of Madagascar plans to increase marine protected area coverage by over one million hectares. To assist this process, we compare four methods for marine spatial planning of Madagascar's west coast. Input data for each method was drawn from the same variables: fishing pressure, exposure to climate change, and biodiversity (habitats, species distributions, biological richness, and biodiversity value. The first method compares visual color classifications of primary variables, the second uses binary combinations of these variables to produce a categorical classification of management actions, the third is a target-based optimization using Marxan, and the fourth is conservation ranking with Zonation. We present results from each method, and compare the latter three approaches for spatial coverage, biodiversity representation, fishing cost and persistence probability. All results included large areas in the north, central, and southern parts of western Madagascar. Achieving 30% representation targets with Marxan required twice the fish catch loss than the categorical method. The categorical classification and Zonation do not consider targets for conservation features. However, when we reduced Marxan targets to 16.3%, matching the representation level of the "strict protection" class of the categorical result, the methods show similar catch losses. The management category portfolio has complete coverage, and presents several management recommendations including strict protection. Zonation produces rapid conservation rankings across large, diverse datasets. Marxan is useful for identifying strict protected areas that meet representation targets, and minimize exposure probabilities for conservation features at low economic cost. We show that methods based on Zonation and a simple combination of variables can produce results comparable to Marxan for species representation and catch losses, demonstrating the value of comparing alternative

  2. Evaluation of the effectiveness and feasibility of the Waste Isolation Pilot Plant engineered alternatives: Final report of the Engineered Alternatives Task Force

    International Nuclear Information System (INIS)

    1991-07-01

    The Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico, is an underground repository designed for the geologic disposal of radioactive wastes resulting from the defense activities and programs of the United States Department of Energy (DOE). The performance of nuclear waste repositories is governed by US Environmental Protection Agency (EPA). The study conducted to demonstrate compliance with this regulation is called performance assessment. The EPA standard requires that DOE provide a reasonable assurance, based on performance assessment, that cumulative releases of radioactivity to the accessible environment will not exceed the standard's criteria. Preliminary performance assessment performed by SNL has indicated that the current design of the WIPP repository, together with the waste forms at the DOE storage and generating sites, may not demonstrate compliance with the EPA Standard. In view of this concern, and prompted by recommendations from external review groups, the DOE established the Engineered Alternatives Task Force (EATF) in September, 1989. The objective of the EATF is to identify potential engineering modifications (referred to as engineered alternatives) to the existing WIPP design and/or to the transuranic (TRU) waste forms, an to evaluate their effectiveness and feasibility in facilitating compliance with the EPA Standard. These alternatives would be designed to completely eliminate or reduce any problems which might cause non-compliance with the EPA Standard. 139 refs., 39 figs., 124 tabs

  3. An alternative to the standard spatial econometric approaches in hedonic house price models

    DEFF Research Database (Denmark)

    von Graevenitz, Kathrine; Panduro, Toke Emil

    2015-01-01

    Omitted, misspecified, or mismeasured spatially varying characteristics are a cause for concern in hedonic house price models. Spatial econometrics or spatial fixed effects have become popular ways of addressing these concerns. We discuss the limitations of standard spatial approaches to hedonic...

  4. Changes in prefrontal neuronal activity after learning to perform a spatial working memory task.

    Science.gov (United States)

    Qi, Xue-Lian; Meyer, Travis; Stanford, Terrence R; Constantinidis, Christos

    2011-12-01

    The prefrontal cortex is considered essential for learning to perform cognitive tasks though little is known about how the representation of stimulus properties is altered by learning. To address this issue, we recorded neuronal activity in monkeys before and after training on a task that required visual working memory. After the subjects learned to perform the task, we observed activation of more prefrontal neurons and increased activity during working memory maintenance. The working memory-related increase in firing rate was due mostly to regular-spiking putative pyramidal neurons. Unexpectedly, the selectivity of neurons for stimulus properties and the ability of neurons to discriminate between stimuli decreased as the information about stimulus properties was apparently present in neural firing prior to training and neuronal selectivity degraded after training in the task. The effect was robust and could not be accounted for by differences in sampling sites, selection of neurons, level of performance, or merely the elapse of time. The results indicate that, in contrast to the effects of perceptual learning, mastery of a cognitive task degrades the apparent stimulus selectivity as neurons represent more abstract information related to the task. This effect is countered by the recruitment of more neurons after training.

  5. Increased Variability and Asymmetric Expansion of the Hippocampal Spatial Representation in a Distal Cue-Dependent Memory Task.

    Science.gov (United States)

    Park, Seong-Beom; Lee, Inah

    2016-08-01

    Place cells in the hippocampus fire at specific positions in space, and distal cues in the environment play critical roles in determining the spatial firing patterns of place cells. Many studies have shown that place fields are influenced by distal cues in foraging animals. However, it is largely unknown whether distal-cue-dependent changes in place fields appear in different ways in a memory task if distal cues bear direct significance to achieving goals. We investigated this possibility in this study. Rats were trained to choose different spatial positions in a radial arm in association with distal cue configurations formed by visual cue sets attached to movable curtains around the apparatus. The animals were initially trained to associate readily discernible distal cue configurations (0° vs. 80° angular separation between distal cue sets) with different food-well positions and then later experienced ambiguous cue configurations (14° and 66°) intermixed with the original cue configurations. Rats showed no difficulty in transferring the associated memory formed for the original cue configurations when similar cue configurations were presented. Place field positions remained at the same locations across different cue configurations, whereas stability and coherence of spatial firing patterns were significantly disrupted when ambiguous cue configurations were introduced. Furthermore, the spatial representation was extended backward and skewed more negatively at the population level when processing ambiguous cue configurations, compared with when processing the original cue configurations only. This effect was more salient for large cue-separation conditions than for small cue-separation conditions. No significant rate remapping was observed across distal cue configurations. These findings suggest that place cells in the hippocampus dynamically change their detailed firing characteristics in response to a modified cue environment and that some of the firing

  6. Spontaneous alternation: A potential gateway to spatial working memory in Drosophila.

    Science.gov (United States)

    Lewis, Sara A; Negelspach, David C; Kaladchibachi, Sevag; Cowen, Stephen L; Fernandez, Fabian

    2017-07-01

    Despite their ubiquity in biomedical research, Drosophila have yet to be widely employed as model organisms in psychology. Many complex human-like behaviors are observed in Drosophila, which exhibit elaborate displays of inter-male aggression and female courtship, self-medication with alcohol in response to stress, and even cultural transmission of social information. Here, we asked whether Drosophila can demonstrate behavioral indices of spatial working memory in a Y-maze, a classic test of memory function and novelty-seeking in rodents. Our data show that Drosophila, like rodents, alternate their visits among the three arms of a Y-maze and spontaneously favor entry into arms they have explored less recently versus ones they have just seen. These findings suggest that Drosophila possess some of the information-seeking and working memory facilities mammals depend on to navigate through space and might be relevant models for understanding human psychological phenomena such as curiosity. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Final report, Task 2: alternative waste management options, Nuclear Fuel Services, Inc., high level waste

    International Nuclear Information System (INIS)

    1978-01-01

    Of the alternatives considered for disposal of the high-level waste in tanks 8D2 and 8D4, the following process is recommended: homogenization of the contents of tank 8D2, centrifugation of the sludge and supernate, mixing of the 8D4 acid waste with the centrifuged sludge, and converting the mixture to a borosilicate glass using the Hanford spray calciner/in-can melter

  8. Development and evaluation of a specialized task taxonomy for spatial planning - A map literacy experiment with topographic maps

    Science.gov (United States)

    Rautenbach, Victoria; Coetzee, Serena; Çöltekin, Arzu

    2017-05-01

    Topographic maps are among the most commonly used map types, however, their complex and information-rich designs depicting natural, human-made and cultural features make them difficult to read. Regardless of their complexity, spatial planners make extensive use of topographic maps in their work. On the other hand, various studies suggest that map literacy among the development planning professionals in South Africa is not very high. The widespread use of topographic maps combined with the low levels of map literacy presents challenges for effective development planning. In this paper we address some of these challenges by developing a specialized task taxonomy based on systematically assessed map literacy levels; and conducting an empirical experiment with topographic maps to evaluate our task taxonomy. In such empirical studies if non-realistic tasks are used, the results of map literacy tests may be skewed. Furthermore, experience and familiarity with the studied map type play a role in map literacy. There is thus a need to develop map literacy tests aimed at planners specifically. We developed a taxonomy of realistic map reading tasks typically executed during the planning process. The taxonomy defines six levels tasks of increasing difficulty and complexity, ranging from recognising symbols to extracting knowledge. We hypothesized that competence in the first four levels indicates functional map literacy. In this paper, we present results from an empirical experiment with 49 map literate participants solving a subset of tasks from the first four levels of the taxonomy with a topographic map. Our findings suggest that the proposed taxonomy is a good reference for evaluating topographic map literacy. Participants solved the tasks on all four levels as expected and we therefore conclude that the experiment based on the first four levels of the taxonomy successfully determined the functional map literacy of the participants. We plan to continue the study for the

  9. Comparison of alternative spatial resolutions in the application of a spatially distributed biogeochemical model over complex terrain

    Science.gov (United States)

    Turner, D.P.; Dodson, R.; Marks, D.

    1996-01-01

    Spatially distributed biogeochemical models may be applied over grids at a range of spatial resolutions, however, evaluation of potential errors and loss of information at relatively coarse resolutions is rare. In this study, a georeferenced database at the 1-km spatial resolution was developed to initialize and drive a process-based model (Forest-BGC) of water and carbon balance over a gridded 54976 km2 area covering two river basins in mountainous western Oregon. Corresponding data sets were also prepared at 10-km and 50-km spatial resolutions using commonly employed aggregation schemes. Estimates were made at each grid cell for climate variables including daily solar radiation, air temperature, humidity, and precipitation. The topographic structure, water holding capacity, vegetation type and leaf area index were likewise estimated for initial conditions. The daily time series for the climatic drivers was developed from interpolations of meteorological station data for the water year 1990 (1 October 1989-30 September 1990). Model outputs at the 1-km resolution showed good agreement with observed patterns in runoff and productivity. The ranges for model inputs at the 10-km and 50-km resolutions tended to contract because of the smoothed topography. Estimates for mean evapotranspiration and runoff were relatively insensitive to changing the spatial resolution of the grid whereas estimates of mean annual net primary production varied by 11%. The designation of a vegetation type and leaf area at the 50-km resolution often subsumed significant heterogeneity in vegetation, and this factor accounted for much of the difference in the mean values for the carbon flux variables. Although area wide means for model outputs were generally similar across resolutions, difference maps often revealed large areas of disagreement. Relatively high spatial resolution analyses of biogeochemical cycling are desirable from several perspectives and may be particularly important in the

  10. When do objects become landmarks? A VR study of the effect of task relevance on spatial memory.

    Directory of Open Access Journals (Sweden)

    Xue Han

    Full Text Available We investigated how objects come to serve as landmarks in spatial memory, and more specifically how they form part of an allocentric cognitive map. Participants performing a virtual driving task incidentally learned the layout of a virtual town and locations of objects in that town. They were subsequently tested on their spatial and recognition memory for the objects. To assess whether the objects were encoded allocentrically we examined pointing consistency across tested viewpoints. In three experiments, we found that spatial memory for objects at navigationally relevant locations was more consistent across tested viewpoints, particularly when participants had more limited experience of the environment. When participants' attention was focused on the appearance of objects, the navigational relevance effect was eliminated, whereas when their attention was focused on objects' locations, this effect was enhanced, supporting the hypothesis that when objects are processed in the service of navigation, rather than merely being viewed as objects, they engage qualitatively distinct attentional systems and are incorporated into an allocentric spatial representation. The results are consistent with evidence from the neuroimaging literature that when objects are relevant to navigation, they not only engage the ventral "object processing stream", but also the dorsal stream and medial temporal lobe memory system classically associated with allocentric spatial memory.

  11. Strategies for human-driven robot comprehension of spatial descriptions by older adults in a robot fetch task.

    Science.gov (United States)

    Carlson, Laura; Skubic, Marjorie; Miller, Jared; Huo, Zhiyu; Alexenko, Tatiana

    2014-07-01

    This contribution presents a corpus of spatial descriptions and describes the development of a human-driven spatial language robot system for their comprehension. The domain of application is an eldercare setting in which an assistive robot is asked to "fetch" an object for an elderly resident based on a natural language spatial description given by the resident. In Part One, we describe a corpus of naturally occurring descriptions elicited from a group of older adults within a virtual 3D home that simulates the eldercare setting. We contrast descriptions elicited when participants offered descriptions to a human versus robot avatar, and under instructions to tell the addressee how to find the target versus where the target is. We summarize the key features of the spatial descriptions, including their dynamic versus static nature and the perspective adopted by the speaker. In Part Two, we discuss critical cognitive and perceptual processing capabilities necessary for the robot to establish a common ground with the human user and perform the "fetch" task. Based on the collected corpus, we focus here on resolving the perspective ambiguity and recognizing furniture items used as landmarks in the descriptions. Taken together, the work presented here offers the key building blocks of a robust system that takes as input natural spatial language descriptions and produces commands that drive the robot to successfully fetch objects within our eldercare scenario. Copyright © 2014 Cognitive Science Society, Inc.

  12. Differences between appetitive and aversive reinforcement on reorientation in a spatial working memory task.

    Science.gov (United States)

    Golob, Edward J; Taube, Jeffrey S

    2002-10-17

    Tasks using appetitive reinforcers show that following disorientation rats use the shape of an arena to reorient, and cannot distinguish two geometrically similar corners to obtain a reward, despite the presence of a prominent visual cue that provides information to differentiate the two corners. Other studies show that disorientation impairs performance on certain appetitive, but not aversive, tasks. This study evaluated whether rats would make similar geometric errors in a working memory task that used aversive reinforcement. We hypothesized that in a task that used aversive reinforcement rats that were initially disoriented would not reorient by arena shape and thus make similar geometric errors. Tests were performed in a rectangular arena having one polarizing cue. In the appetitive condition water consumption was the reward. The aversive condition was a water maze task with reinforcement provided by escape to a hidden platform. In the aversive condition rats returned to the reinforced corner significantly more often than in the dry condition, and did not favor the diagonally opposite corner. Results show that rats can use cues besides arena shape to reorient in an aversive reinforcement condition. These findings may also reflect different strategies, with an escape/homing strategy in the wet condition and a foraging strategy in the dry condition.

  13. An alternative to the standard spatial econometric approaches in hedonic house price models

    DEFF Research Database (Denmark)

    Veie, Kathrine Lausted; Panduro, Toke Emil

    Hedonic models are subject to spatially correlated errors which are a symptom of omitted spatial variables, mis-specification or mismeasurement. Methods have been developed to address this problem through the use of spatial econometrics or spatial fixed effects. However, often spatial correlation is...... varying characteristics markedly. This suggests that omitted variable bias may remain an important problem. We advocate for an increased use of sensitivity analysis to determine robustness of estimates to different models of the (omitted) spatial processes....

  14. The effects of visual discriminability and rotation angle on 30-month-olds’ search performance in spatial rotation tasks

    Directory of Open Access Journals (Sweden)

    Mirjam Ebersbach

    2016-10-01

    Full Text Available Tracking objects that are hidden and then moved is a crucial ability related to object permanence, which develops across several stages in early childhood. In spatial rotation tasks, children observe a target object that is hidden in one of two or more containers before the containers are rotated around a fixed axis. Usually, 30-month-olds fail to find the hidden object after it was rotated by 180°. We examined whether visual discriminability of the containers improves 30-month-olds’ success in this task and whether children perform better after 90° than after 180° rotations. Two potential hiding containers with same or different colors were placed on a board that was rotated by 90° or 180° in a within-subjects design. Children (N = 29 performed above chance level in all four conditions. Their overall success in finding the object did not improve by differently colored containers. However, different colors prevented children from showing an inhibition bias in 90° rotations, that is, choosing the empty container more often when it was located close to them than when it was farther away: This bias emerged in the same colors condition but not in the different colors condition. Results are discussed in view of particular challenges that might facilitate or deteriorate spatial rotation tasks for young children.

  15. The Effects of Visual Discriminability and Rotation Angle on 30-Month-Olds' Search Performance in Spatial Rotation Tasks.

    Science.gov (United States)

    Ebersbach, Mirjam; Nawroth, Christian

    2016-01-01

    Tracking objects that are hidden and then moved is a crucial ability related to object permanence, which develops across several stages in early childhood. In spatial rotation tasks, children observe a target object that is hidden in one of two or more containers before the containers are rotated around a fixed axis. Usually, 30-month-olds fail to find the hidden object after it was rotated by 180°. We examined whether visual discriminability of the containers improves 30-month-olds' success in this task and whether children perform better after 90° than after 180° rotations. Two potential hiding containers with same or different colors were placed on a board that was rotated by 90° or 180° in a within-subjects design. Children ( N = 29) performed above chance level in all four conditions. Their overall success in finding the object did not improve by differently colored containers. However, different colors prevented children from showing an inhibition bias in 90° rotations, that is, choosing the empty container more often when it was located close to them than when it was farther away: This bias emerged in the same colors condition but not in the different colors condition. Results are discussed in view of particular challenges that might facilitate or deteriorate spatial rotation tasks for young children.

  16. The Effects of Visual Discriminability and Rotation Angle on 30-Month-Olds’ Search Performance in Spatial Rotation Tasks

    Science.gov (United States)

    Ebersbach, Mirjam; Nawroth, Christian

    2016-01-01

    Tracking objects that are hidden and then moved is a crucial ability related to object permanence, which develops across several stages in early childhood. In spatial rotation tasks, children observe a target object that is hidden in one of two or more containers before the containers are rotated around a fixed axis. Usually, 30-month-olds fail to find the hidden object after it was rotated by 180°. We examined whether visual discriminability of the containers improves 30-month-olds’ success in this task and whether children perform better after 90° than after 180° rotations. Two potential hiding containers with same or different colors were placed on a board that was rotated by 90° or 180° in a within-subjects design. Children (N = 29) performed above chance level in all four conditions. Their overall success in finding the object did not improve by differently colored containers. However, different colors prevented children from showing an inhibition bias in 90° rotations, that is, choosing the empty container more often when it was located close to them than when it was farther away: This bias emerged in the same colors condition but not in the different colors condition. Results are discussed in view of particular challenges that might facilitate or deteriorate spatial rotation tasks for young children. PMID:27812346

  17. Task-irrelevant distractors in the delay period interfere selectively with visual short-term memory for spatial locations.

    Science.gov (United States)

    Marini, Francesco; Scott, Jerry; Aron, Adam R; Ester, Edward F

    2017-07-01

    Visual short-term memory (VSTM) enables the representation of information in a readily accessible state. VSTM is typically conceptualized as a form of "active" storage that is resistant to interference or disruption, yet several recent studies have shown that under some circumstances task-irrelevant distractors may indeed disrupt performance. Here, we investigated how task-irrelevant visual distractors affected VSTM by asking whether distractors induce a general loss of remembered information or selectively interfere with memory representations. In a VSTM task, participants recalled the spatial location of a target visual stimulus after a delay in which distractors were presented on 75% of trials. Notably, the distractor's eccentricity always matched the eccentricity of the target, while in the critical conditions the distractor's angular position was shifted either clockwise or counterclockwise relative to the target. We then computed estimates of recall error for both eccentricity and polar angle. A general interference model would predict an effect of distractors on both polar angle and eccentricity errors, while a selective interference model would predict effects of distractors on angle but not on eccentricity errors. Results showed that for stimulus angle there was an increase in the magnitude and variability of recall errors. However, distractors had no effect on estimates of stimulus eccentricity. Our results suggest that distractors selectively interfere with VSTM for spatial locations.

  18. Altered visual-spatial attention to task-irrelevant information is associated with falls risk in older adults

    Science.gov (United States)

    Nagamatsu, Lindsay S.; Munkacsy, Michelle; Liu-Ambrose, Teresa; Handy, Todd C.

    2014-01-01

    Executive cognitive functions play a critical role in falls risk – a pressing health care issue in seniors. In particular, intact attentional processing is integral for safe mobility and navigation. However, the specific contribution of impaired visual-spatial attention in falls remains unclear. In this study, we examined the association between visual-spatial attention to task-irrelevant stimuli and falls risk in community-dwelling older adults. Participants completed a visual target discrimination task at fixation while task-irrelevant probes were presented in both visual fields. We assessed attention to left and right peripheral probes using event-related potentials (ERPs). Falls risk was determined using the valid and reliable Physiological Profile Assessment (PPA). We found a significantly positive association between reduced attentional facilitation, as measured by the N1 ERP component, and falls risk. This relationship was specific to probes presented in the left visual field and measured at ipsilateral electrode sites. Our results suggest that fallers exhibit reduced attention to the left side of visual space and provide evidence that impaired right hemispheric function and/or structure may contribute to falls. PMID:24436970

  19. Pore Network Modeling: Alternative Methods to Account for Trapping and Spatial Correlation

    KAUST Repository

    De La Garza Martinez, Pablo

    2016-05-01

    Pore network models have served as a predictive tool for soil and rock properties with a broad range of applications, particularly in oil recovery, geothermal energy from underground reservoirs, and pollutant transport in soils and aquifers [39]. They rely on the representation of the void space within porous materials as a network of interconnected pores with idealised geometries. Typically, a two-phase flow simulation of a drainage (or imbibition) process is employed, and by averaging the physical properties at the pore scale, macroscopic parameters such as capillary pressure and relative permeability can be estimated. One of the most demanding tasks in these models is to include the possibility of fluids to remain trapped inside the pore space. In this work I proposed a trapping rule which uses the information of neighboring pores instead of a search algorithm. This approximation reduces the simulation time significantly and does not perturb the accuracy of results. Additionally, I included spatial correlation to generate the pore sizes using a matrix decomposition method. Results show higher relative permeabilities and smaller values for irreducible saturation, which emphasizes the effects of ignoring the intrinsic correlation seen in pore sizes from actual porous media. Finally, I implemented the algorithm from Raoof et al. (2010) [38] to generate the topology of a Fontainebleau sandstone by solving an optimization problem using the steepest descent algorithm with a stochastic approximation for the gradient. A drainage simulation is performed on this representative network and relative permeability is compared with published results. The limitations of this algorithm are discussed and other methods are suggested to create a more faithful representation of the pore space.

  20. Pore Network Modeling: Alternative Methods to Account for Trapping and Spatial Correlation

    KAUST Repository

    De La Garza Martinez, Pablo

    2016-01-01

    Pore network models have served as a predictive tool for soil and rock properties with a broad range of applications, particularly in oil recovery, geothermal energy from underground reservoirs, and pollutant transport in soils and aquifers [39]. They rely on the representation of the void space within porous materials as a network of interconnected pores with idealised geometries. Typically, a two-phase flow simulation of a drainage (or imbibition) process is employed, and by averaging the physical properties at the pore scale, macroscopic parameters such as capillary pressure and relative permeability can be estimated. One of the most demanding tasks in these models is to include the possibility of fluids to remain trapped inside the pore space. In this work I proposed a trapping rule which uses the information of neighboring pores instead of a search algorithm. This approximation reduces the simulation time significantly and does not perturb the accuracy of results. Additionally, I included spatial correlation to generate the pore sizes using a matrix decomposition method. Results show higher relative permeabilities and smaller values for irreducible saturation, which emphasizes the effects of ignoring the intrinsic correlation seen in pore sizes from actual porous media. Finally, I implemented the algorithm from Raoof et al. (2010) [38] to generate the topology of a Fontainebleau sandstone by solving an optimization problem using the steepest descent algorithm with a stochastic approximation for the gradient. A drainage simulation is performed on this representative network and relative permeability is compared with published results. The limitations of this algorithm are discussed and other methods are suggested to create a more faithful representation of the pore space.

  1. Female and male pigs' performance in a spatial holeboard and judgment bias task

    NARCIS (Netherlands)

    Roelofs, Sanne; Nordquist, Rebecca E.; van der Staay, Franz Josef

    2017-01-01

    Studies of the cognitive abilities of pigs are increasing in number, due to their relevance for the fields of animal welfare and biomedical research. While both female and male pigs have been used in cognitive tasks, possible sex differences in performance have not yet received extensive attention.

  2. Gender Perspectives on Spatial Tasks in a National Assessment: A Secondary Data Analysis

    Science.gov (United States)

    Logan, Tracy; Lowrie, Tom

    2017-01-01

    Most large-scale summative assessments present results in terms of cumulative scores. Although such descriptions can provide insights into general trends over time, they do not provide detail of how students solved the tasks. Less restrictive access to raw data from these summative assessments has occurred in recent years, resulting in…

  3. Comparing "pick and place" task in spatial Augmented Reality versus non-immersive Virtual Reality for rehabilitation setting.

    Science.gov (United States)

    Khademi, Maryam; Hondori, Hossein Mousavi; Dodakian, Lucy; Cramer, Steve; Lopes, Cristina V

    2013-01-01

    Introducing computer games to the rehabilitation market led to development of numerous Virtual Reality (VR) training applications. Although VR has provided tremendous benefit to the patients and caregivers, it has inherent limitations, some of which might be solved by replacing it with Augmented Reality (AR). The task of pick-and-place, which is part of many activities of daily living (ADL's), is one of the major affected functions stroke patients mainly expect to recover. We developed an exercise consisting of moving an object between various points, following a flash light that indicates the next target. The results show superior performance of subjects in spatial AR versus non-immersive VR setting. This could be due to the extraneous hand-eye coordination which exists in VR whereas it is eliminated in spatial AR.

  4. WE-DE-207B-05: Measuring Spatial Resolution in Digital Breast Tomosynthesis: Update of AAPM Task Group 245

    Energy Technology Data Exchange (ETDEWEB)

    Scaduto, DA; Hu, Y-H; Zhao, W [Stony Brook Medicine, Stony Brook, NY (United States); Goodsitt, M; Chan, H-P [University Michigan, Ann Arbor, MI (United States); Olafsdottir, H [Image Owl, 105 Reykjavik (Iceland); Das, M [University Houston, Houston, TX (United States); Fredenberg, E [Philips Healthcare, Solna (Sweden); Geiser, W [UT MD Anderson Cancer Center, Houston, TX (United States); Goodenough, D [The George Washington University, Washington, DC (United States); Heid, P [ARCADES, Marseille (France); Liu, B [Massachusetts General Hospital, Boston, MA (United States); Mainprize, J [Sunnybrook Health Sciences Centre, North York, ON (Canada); Reiser, I [The University of Chicago, Chicago, IL (United States); Van Engen, R [LRCB, Nijmegen (Netherlands); Varchena, V [CIRS Inc., Norfolk, VA (United States); Vecchio, S [I.M.S., Pontecchio Marconi (Italy); Glick, S [Food and Drug Administration, Silver Spring, MD (United States)

    2016-06-15

    Purpose: Spatial resolution in digital breast tomosynthesis (DBT) is affected by inherent/binned detector resolution, oblique entry of x-rays, and focal spot size/motion; the limited angular range further limits spatial resolution in the depth-direction. While DBT is being widely adopted clinically, imaging performance metrics and quality control protocols have not been standardized. AAPM Task Group 245 on Tomosynthesis Quality Control has been formed to address this deficiency. Methods: Methods of measuring spatial resolution are evaluated using two prototype quality control phantoms for DBT. Spatial resolution in the detector plane is measured in projection and reconstruction domains using edge-spread function (ESF), point-spread function (PSF) and modulation transfer function (MTF). Spatial resolution in the depth-direction and effective slice thickness are measured in the reconstruction domain using slice sensitivity profile (SSP) and artifact spread function (ASF). An oversampled PSF in the depth-direction is measured using a 50 µm angulated tungsten wire, from which the MTF is computed. Object-dependent PSF is derived and compared with ASF. Sensitivity of these measurements to phantom positioning, imaging conditions and reconstruction algorithms is evaluated. Results are compared from systems of varying acquisition geometry (9–25 projections over 15–60°). Dependence of measurements on feature size is investigated. Results: Measurements of spatial resolution using PSF and LSF are shown to depend on feature size; depth-direction spatial resolution measurements are shown to similarly depend on feature size for ASF, though deconvolution with an object function removes feature size-dependence. A slanted wire may be used to measure oversampled PSFs, from which MTFs may be computed for both in-plane and depth-direction resolution. Conclusion: Spatial resolution measured using PSF is object-independent with sufficiently small object; MTF is object

  5. Attention capture without awareness in a non-spatial selection task.

    Science.gov (United States)

    Oriet, Chris; Pandey, Mamata; Kawahara, Jun-Ichiro

    2017-02-01

    Distractors presented prior to a critical target in a rapid sequence of visually-presented items induce a lag-dependent deficit in target identification, particularly when the distractor shares a task-relevant feature of the target. Presumably, such capture of central attention is important for bringing a target into awareness. The results of the present investigation suggest that greater capture of attention by a distractor is not accompanied by greater awareness of it. Moreover, awareness tends to be limited to superficial characteristics of the target such as colour. The findings are interpreted within the context of a model that assumes sudden increases in arousal trigger selection of information for consolidation in working memory. In this conceptualization, prolonged analysis of distractor items sharing task-relevant features leads to larger target identification deficits (i.e., greater capture) but no increase in awareness. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Memory modulation across neural systems: intra-amygdala glucose reverses deficits caused by intraseptal morphine on a spatial task but not on an aversive task.

    Science.gov (United States)

    McNay, E C; Gold, P E

    1998-05-15

    Based largely on dissociations of the effects of different lesions on learning and memory, memories for different attributes appear to be organized in independent neural systems. Results obtained with direct injections of drugs into one brain region at a time support a similar conclusion. The present experiments investigated the effects of simultaneous pharmacological manipulation of two neural systems, the amygdala and the septohippocampal system, to examine possible interactions of memory modulation across systems. Morphine injected into the medial septum impaired memory both for avoidance training and during spontaneous alternation. When glucose was concomitantly administered to the amygdala, glucose reversed the morphine-induced deficits in memory during alternation but not for avoidance training. These results suggest that the amygdala is involved in modulation of spatial memory processes and that direct injections of memory-modulating drugs into the amygdala do not always modulate memory for aversive events. These findings are contrary to predictions from the findings of lesion studies and of studies using direct injections of drugs into single brain areas. Thus, the independence of neural systems responsible for processing different classes of memory is less clear than implied by studies using lesions or injections of drugs into single brain areas.

  7. How role distribution influences choice of spatial reference frames in a virtual collaborative task

    OpenAIRE

    Pouliquen-Lardy , Lauriane; Milleville-Pennel , Isabelle; Guillaume , François; Mars , Franck

    2014-01-01

    International audience; We investigated the effects of role distribution on individuals' choice of reference frames in a two-person task. Pairs of participants had to move a virtual block in a constraint immersive virtual environment: only one of them could manipulate the ob-ject, his coworker guided him in the VE. Results show that the guiding operators used more addressee-centered frames of ref-erence than the manipulators. They also suggest that the guides tried to facilitate the manipulat...

  8. Spatial task for rats testing position recognition of an object displayed on a computer screen

    Czech Academy of Sciences Publication Activity Database

    Klement, Daniel; Levčík, David; Dušková, Lenka; Nekovářová, Tereza

    2010-01-01

    Roč. 207, č. 2 (2010), s. 480-489 ISSN 0166-4328 R&D Projects: GA ČR(CZ) GA309/09/0286; GA MŠk(CZ) 1M0517; GA MŠk(CZ) LC554 Institutional research plan: CEZ:AV0Z50110509 Keywords : spatial cognition * operant conditioning * reinforcement learning Subject RIV: FH - Neurology Impact factor: 3.393, year: 2010

  9. Introducing moving objects into behavioral spatial tasks: moving object avoidance in rats

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Jan; Telenský, Petr; Blahna, Karel; Pašťálková, Eva; Bureš, Jan

    2005-01-01

    Roč. 43, č. 4 (2005), s. 202-204 ISSN 0960-7560 R&D Projects: GA MŠk(CZ) 1M0517; GA ČR(CZ) GA309/03/0715; GA ČR(CZ) GD206/05/H012 Institutional research plan: CEZ:AV0Z5011922 Keywords : spatial avoidance * rat Subject RIV: FH - Neurology

  10. Temporal Oculomotor Inhibition of Return and Spatial Facilitation of Return in a Visual Encoding Task

    Directory of Open Access Journals (Sweden)

    Steven G Luke

    2013-07-01

    Full Text Available Oculomotor inhibition of return (O-IOR is an increase in saccade latency prior to an eye movement to a recently fixated location compared to other locations. It has been proposed that this temporal O-IOR may have spatial consequences, facilitating foraging by inhibiting return to previously attended regions. In order to test this possibility, participants viewed arrays of objects and of words while their eye movements were recorded. Temporal O-IOR was observed, with equivalent effects for object and word arrays, indicating that temporal O-IOR is an oculomotor phenomenon independent of array content. There was no evidence for spatial inhibition of return. Instead, spatial facilitation of return was observed: Participants were significantly more likely than chance to make return saccades and to refixate just-visited locations. Further, the likelihood of making a return saccade to an object or word was contingent on the amount of time spent viewing that object or word before leaving it. This suggests that, unlike temporal O-IOR, return probability is influenced by cognitive processing. Taken together, these results are inconsistent with the hypothesis that inhibition of return functions as a foraging facilitator. The results also provide strong evidence for a different oculomotor bias that could serve as a foraging facilitator: saccadic momentum, a tendency to repeat the most recently executed saccade program. We suggest that models of visual attention could incorporate saccadic momentum in place of inhibition of return.

  11. Audiotactile integration is reduced in congenital blindness in a spatial ventriloquism task.

    Science.gov (United States)

    Occelli, Valeria; Bruns, Patrick; Zampini, Massimiliano; Röder, Brigitte

    2012-01-01

    In the ventriloquism effect, the presentation of spatially discrepant visual information biases the localization of simultaneously presented sounds. Recently, an analogous spatial influence of touch on audition has been observed. By manipulating hand posture, it has been demonstrated that this audiotactile ventriloquist effect predominantly operates in an external frame of reference. In the present study, we examined the contribution of developmental vision to audiotactile interactions as indicated by the ventriloquism effect. Congenitally blind, late blind and sighted adults were asked to report the perceived location of sounds presented from a left, a central or a right location. Auditory stimuli were either delivered alone or concurrently with touches at the left or the right hand. The hands were located to the right and to the left of the lateral speakers and participants either adopted an uncrossed or a crossed hand posture. While sighted controls and late blind participants similarly mislocalized auditory stimuli toward the concurrent tactile stimuli in bimodal trials, the congenitally blind showed a reduced ventriloquism effect. All groups showed a reduced audiotactile ventriloquism effect in the crossed hand condition. However, the magnitude of the reduction was significantly larger in the group of congenitally blind than in the group of sighted controls. These results suggest reduced audio-tactile interactions in spatial processing following a lack of visual input from birth. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Age-related differences in cortical activity during a visuo-spatial working memory task with facial stimuli.

    Directory of Open Access Journals (Sweden)

    Flávia Schechtman Belham

    Full Text Available Emotion, importantly displayed by facial expressions, is one of the most significant memory modulators. The interaction between memory and the different emotional valences change across lifespan, while young adults (YA are expected to better recall negative events (Negativity Bias Hypothesis, older adults (OA tend to focus on positive stimuli (Positivity Effect Hypothesis. This research work aims at verifying whether cortical electrical activity of these two age groups would also be differently influenced by emotional valences in a visuo-spatial working memory task. 27 YA (13 males and 25 OA (14 males, all healthy volunteers, underwent electroencephalographic recordings (21 scalp electrodes montage, while performing the Spatial Delayed Recognition Span Task using a touch screen with different stimuli categories: neutral, positive and negative faces and geometric pictures. YA obtained higher scores than OA, and showed higher activation of theta and alpha bands in the frontal and midline regions, besides a more evident right-hemispheric asymmetry on alpha band when compared to OA. For both age groups, performance in the task was worse for positive faces than to negative and to neutral faces. Facial stimuli induced a better performance and higher alpha activation on the pre-frontal region for YA, and on the midline, occipital and left temporal regions for OA when compared to geometric figures. The superior performance of YA was expected due to the natural cognitive deficits connected to ageing, as was a better performance with facial stimuli due to the evolutionary importance of faces. These results were related to cortical activity on areas of importance for action-planning, decision making and sustained attention. Taken together, they are in accordance with the Negativity Bias but do not support the Positivity Effect. The methodology used was able to identify age-related differences in cortical activity during emotional mnemonic processing and

  13. Computational modelling and analysis of hippocampal-prefrontal information coding during a spatial decision-making task

    Directory of Open Access Journals (Sweden)

    Thomas eJahans-Price

    2014-03-01

    Full Text Available We introduce a computational model describing rat behaviour and the interactions of neural populations processing spatial and mnemonic information during a maze-based, decision-making task. The model integrates sensory input and implements a working memory to inform decisions at a choice point, reproducing rat behavioural data and predicting the occurrence of turn- and memory-dependent activity in neuronal networks supporting task performance. We tested these model predictions using a new software toolbox (Maze Query Language, MQL to analyse activity of medial prefrontal cortical (mPFC and dorsal hippocampal (dCA1 neurons recorded from 6 adult rats during task performance. The firing rates of dCA1 neurons discriminated context (i.e. the direction of the previous turn, whilst a subset of mPFC neurons was selective for current turn direction or context, with some conjunctively encoding both. mPFC turn-selective neurons displayed a ramping of activity on approach to the decision turn and turn-selectivity in mPFC was significantly reduced during error trials. These analyses complement data from neurophysiological recordings in non-human primates indicating that firing rates of cortical neurons correlate with integration of sensory evidence used to inform decision-making.

  14. The role of social cues in the deployment of spatial attention: Head-body relationships automatically activate directional spatial codes in a Simon task

    Directory of Open Access Journals (Sweden)

    Iwona ePomianowska

    2012-02-01

    Full Text Available The role of body orientation in the orienting and allocation of social attention was examined using an adapted Simon paradigm. Participants categorized the facial expression of forward facing, computer-generated human figures by pressing one of two response keys, each located left or right of the observers’ body midline, while the orientation of the stimulus figure’s body (trunk, arms, and legs, which was the task-irrelevant feature of interest, was manipulated (oriented towards the left or right visual hemifield with respect to the spatial location of the required response. We found that when the orientation of the body was compatible with the required response location, responses were slower relative to when body orientation was incompatible with the response location. This reverse compatibility effect suggests that body orientation is automatically processed into a directional spatial code, but that this code is based on an integration of head and body orientation within an allocentric-based frame of reference. Moreover, we argue that this code may be derived from the motion information implied in the image of a figure when head and body orientation are incongruent. Our results have implications for understanding the nature of the information that affects the allocation of attention for social orienting.

  15. Spatial recognition test: A novel cognition task for assessing topographical memory in mice.

    Science.gov (United States)

    Havolli, Enes; Hill, Mark Dw; Godley, Annie; Goetghebeur, Pascal Jd

    2017-06-01

    Dysfunction in topographical memory is a core feature of several neurological disorders. There is a large unmet medical need to address learning and memory deficits as a whole in central nervous system disease. There are considerable efforts to identify pro-cognitive compounds but current methods are either lengthy or labour intensive. Our test used a two chamber apparatus and is based on the preference of rodents to explore novel environments. It was used firstly to assess topographical memory in mice at different retention intervals (RI) and secondly to investigate the effect of three drugs reported to be beneficial for cognitive decline associated with Alzheimer's disease, namely: donepezil, memantine and levetiracetam. Animals show good memory performance at all RIs tested under four hours. At the four-hour RI, animals show a significantly poorer memory performance which can be rescued using donepezil, memantine and levetiracetam. Using this test we established and validated a spatial recognition paradigm to address topographical memory in mice by showing a decremental time-induced forgetting response and reversing this decrease in performance using pharmacological tools. The spatial recognition test differs from more commonly used visuospatial laboratory tests in both throughput capability and potentially neuroanatomical substrate. This test has the potential to be used to assess cognitive performance in transgenic animals, disease models and to screen putative cognitive enhancers or depressors.

  16. Continuous place avoidance task reveals differences in spatial navigation in male and female rats.

    Science.gov (United States)

    Cimadevilla, J M; Fenton, A A; Bures, J

    2000-01-01

    A new place navigation test was used to estimate the spatial orientation abilities of male and female rats. Animals had to avoid a room frame defined area on a rotating arena, entering of which was punished by mild footshock, i.e. rats had to avoid the same place in the room but different parts of the floor, which was rotated through the punished zone. Because of the rotation of the arena (one revolution per min), animals could not rely on intramaze cues and only extramaze landmarks could be used for accurate navigation. During 8 consecutive days rats were exposed to daily 40-min sessions, consisting of 20-min acquisition and 20-min extinction (shock discontinued). The position of the punished sector centered around one of the four mutually perpendicular azimuths was daily changed in a predetermined sequence. The results showed no male female differences during acquisition and better performance of males during extinction. The performance of females was not affected by estral cycle-related hormonal changes. The findings are discussed in the light of controversial results of research into sex differences in spatial abilities.

  17. Spatial working memory in aging and mild cognitive impairment: effects of task load and contextual cueing.

    Science.gov (United States)

    Kessels, Roy P C; Meulenbroek, Olga; Fernández, Guillén; Olde Rikkert, Marcel G M

    2010-09-01

    Mild Cognitive Impairment (MCI) is characterized by episodic memory deficits, while aspects of working memory may also be implicated, but studies into this latter domain are scarce and results are inconclusive. Using a computerized search paradigm, this study compares 25 young adults, 25 typically aging older adults and 15 amnestic MCI patients as to their working-memory capacities for object-location information and potential differential effects of memory load and additional context cues. An age-related deficit in visuospatial working-memory maintenance was found that became more pronounced with increasing task demands. The MCI group additionally showed reduced maintenance of bound information, i.e., object-location associations, again especially at elevated memory load. No effects of contextual cueing were found. The current findings indicate that working memory should be considered when screening patients for suspected MCI and monitoring its progression.

  18. Wild, free-living rufous hummingbirds do not use geometric cues in a spatial task.

    Science.gov (United States)

    Hornsby, Mark A W; Hurly, T Andrew; Hamilton, Caitlin E; Pritchard, David J; Healy, Susan D

    2014-10-01

    In the laboratory, many species orient themselves using the geometric properties of an enclosure or array and geometric information is often preferred over visual cues. Whether animals use geometric cues when relocating rewarded locations in the wild, however, has rarely been investigated. We presented free-living rufous hummingbirds with a rectangular array of four artificial flowers to investigate learning of rewarded locations using geometric cues. In one treatment, we rewarded two of four flowers at diagonally opposite corners. In a second treatment, we provided a visual cue to the rewarded flower by connecting the flowers with "walls" consisting of four dowels (three white, one blue) laid on the ground connecting each of the flowers. Neither treatment elicited classical geometry results; instead, hummingbirds typically chose one particular flower over all others. When we exchanged that flower with another, hummingbirds tended to visit the original flower. These results suggest that (1) hummingbirds did not use geometric cues, but instead may have used a visually derived cue on the flowers themselves, and (2) using geometric cues may have been more difficult than using visual characteristics. Although hummingbirds typically prefer spatial over visual information, we hypothesize that they will not use geometric cues over stable visual features but that they make use of small, flower-specific visual cues. Such cues may play a more important role in foraging decisions than previously thought. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Food's visually perceived fat content affects discrimination speed in an orthogonal spatial task.

    Science.gov (United States)

    Harrar, Vanessa; Toepel, Ulrike; Murray, Micah M; Spence, Charles

    2011-10-01

    Choosing what to eat is a complex activity for humans. Determining a food's pleasantness requires us to combine information about what is available at a given time with knowledge of the food's palatability, texture, fat content, and other nutritional information. It has been suggested that humans may have an implicit knowledge of a food's fat content based on its appearance; Toepel et al. (Neuroimage 44:967-974, 2009) reported visual-evoked potential modulations after participants viewed images of high-energy, high-fat food (HF), as compared to viewing low-fat food (LF). In the present study, we investigated whether there are any immediate behavioural consequences of these modulations for human performance. HF, LF, or non-food (NF) images were used to exogenously direct participants' attention to either the left or the right. Next, participants made speeded elevation discrimination responses (up vs. down) to visual targets presented either above or below the midline (and at one of three stimulus onset asynchronies: 150, 300, or 450 ms). Participants responded significantly more rapidly following the presentation of a HF image than following the presentation of either LF or NF images, despite the fact that the identity of the images was entirely task-irrelevant. Similar results were found when comparing response speeds following images of high-carbohydrate (HC) food items to low-carbohydrate (LC) food items. These results support the view that people rapidly process (i.e. within a few hundred milliseconds) the fat/carbohydrate/energy value or, perhaps more generally, the pleasantness of food. Potentially as a result of HF/HC food items being more pleasant and thus having a higher incentive value, it seems as though seeing these foods results in a response readiness, or an overall alerting effect, in the human brain.

  20. Seeing the forest before the trees-spatial orientation in freshwater stingrays (Potamotrygon motoro) in a hole-board task.

    Science.gov (United States)

    Schluessel, V; Herzog, H; Scherpenstein, M

    2015-10-01

    Freshwater stingrays (Potamotrygon motoro) have been shown to use a variety of spatial learning strategies including directional, landmark and place learning. In the present study, the significance of landmarks and geometric cues was investigated in a hole-board task. The aim was to determine cue preferences and collect additional information on the orientation mechanisms used in elasmobranchs. In four experiments, five juvenile stingrays had to memorize a fixed goal location within either a rectangular or a circular arena in the presence of goal-associated, signaling landmarks, proximal and distal cues. Transfer tests elucidated which cues the rays used or favored to reach the goal position. All rays successfully solved three of four tasks; as expected, different strategies were used in the process. Small alterations in the positioning of signaling landmarks (causing a spatial conflict between the previous feeding location and the new position of the signaling landmark) caused individuals to visit both locations equally often, whereas large alterations caused animals to ignore signaling cues and return to the previous feeding location. In the last and most complex experiment, three of five rays found the feeding location by remembering the positions of both proximate and distal landmarks in addition to memorizing particular swimming paths. Results showed that rays generally placed more importance on the overall environmental or geometric arrangement of the arena than on (individual) landmarks. This seems ecologically feasible, as distinct landmarks (e.g. rocks, pieces of wood, water plants) in the rays' natural environment may be more easily altered, removed or obscured from view than global ones (e.g. a river bend), which tend to be more stable. Overall, these results confirm those of previous studies, in that freshwater stingrays orient visually, learn quickly and can apply various orientation strategies, which are not mutually exclusive. Copyright © 2015

  1. Transcranial alternating current stimulation (tACS increases risk taking behavior in the Balloon Analogue Risk Task

    Directory of Open Access Journals (Sweden)

    Tal eSela

    2012-02-01

    Full Text Available The process of evaluating risks and benefits involves a complex neural network that includes the dorsolateral prefrontal cortex (DLPFC. It has been proposed that in conflict and reward situations, theta-band (4–8 Hz oscillatory activity in the frontal cortex may reflect an electrophysiological mechanism for coordinating neural networks monitoring behavior, as well as facilitating task-specific adaptive changes. The goal of the present study was to investigate the hypothesis that theta-band oscillatory balance between right and left frontal and prefrontal regions, with a predominance role to the right hemisphere, is crucial for regulatory control during decision-making under risk. In order to explore this hypothesis, we used transcranial Alternating Current Stimulation (tACS, a novel technique that provides the opportunity to explore the functional role of neuronal oscillatory activities and to establish a causal link between specific oscillations and functional lateralization in risky decision-making situations. For this aim, healthy participants were randomly allocated to one of three stimulation groups (LH stimulation / RH stimulation / Sham stimulation, with active AC stimulation delivered in a frequency-dependent manner (at 6.5 Hz; 1mA peak to-peak. During the AC stimulation, participants performed the Balloon Analog Risk Task. This experiment revealed that participants receiving LH stimulation displayed riskier decision-making style compared to sham and RH stimulation groups. However, there was no difference in decision-making behaviors between sham and RH stimulation groups. The current study extends the notion that DLPFC activity is critical for adaptive decision-making in the context of risk-taking and emphasis the role of theta-band oscillatory activity during risky decision-making situations.

  2. Left neglected, but only in far space: Spatial biases in healthy participants revealed in a visually-guided grasping task

    Directory of Open Access Journals (Sweden)

    Natalie ede Bruin

    2014-01-01

    Full Text Available Hemispatial neglect is a common outcome of stroke that is characterised by the inability to orient towards, and attend to stimuli in contralesional space. It is established that hemispatial neglect has a perceptual component, however, the presence and severity of motor impairments is controversial. Establishing the nature of space use and spatial biases during visually-guided actions amongst healthy individuals is critical to understanding the presence of visuomotor deficits in patients with neglect. Accordingly, three experiments were conducted to investigate the effect of object spatial location on patterns of grasping. Experiment 1 required right-handed participants to reach and grasp for blocks in order to construct 3D models. The blocks were scattered on a tabletop divided into equal size quadrants: left near, left far, right near, and right far. Identical sets of building blocks were available in each quadrant. Space use was dynamic, with participants initially grasping blocks from right near space and tending to ‘neglect’ left far space until the final stages of the task. Experiment 2 repeated the protocol with left-handed participants. Remarkably, left-handed participants displayed a similar pattern of space use to right-handed participants. In Experiment 3 eye movements were examined to investigate whether ‘neglect’ for grasping in left far reachable space had its origins in attentional biases. It was found that patterns of eye movements mirrored patterns of reach-to-grasp movements. We conclude that there are spatial biases during visually-guided grasping, specifically, a tendency to neglect left far reachable space, and that this ‘neglect’ is attentional in origin. The results raise the possibility that visuomotor impairments reported among patients with right hemisphere lesions when working in contralesional space may result in part from this inherent tendency to ‘neglect’ left far space irrespective of the presence

  3. The Social Attribution Task-Multiple Choice (SAT-MC): A Psychometric and Equivalence Study of an Alternate Form.

    Science.gov (United States)

    Johannesen, Jason K; Lurie, Jessica B; Fiszdon, Joanna M; Bell, Morris D

    2013-01-01

    The Social Attribution Task-Multiple Choice (SAT-MC) uses a 64-second video of geometric shapes set in motion to portray themes of social relatedness and intentions. Considered a test of "Theory of Mind," the SAT-MC assesses implicit social attribution formation while reducing verbal and basic cognitive demands required of other common measures. We present a comparability analysis of the SAT-MC and the new SAT-MC-II, an alternate form created for repeat testing, in a university sample (n = 92). Score distributions and patterns of association with external validation measures were nearly identical between the two forms, with convergent and discriminant validity supported by association with affect recognition ability and lack of association with basic visual reasoning. Internal consistency of the SAT-MC-II was superior (alpha = .81) to the SAT-MC (alpha = .56). Results support the use of SAT-MC and new SAT-MC-II as equivalent test forms. Demonstrating relatively higher association to social cognitive than basic cognitive abilities, the SAT-MC may provide enhanced sensitivity as an outcome measure of social cognitive intervention trials.

  4. Stiffness analysis and comparison of a Biglide parallel grinder with alternative spatial modular parallelograms

    DEFF Research Database (Denmark)

    Wu, Guanglei; Zou, Ping

    2017-01-01

    This paper deals with the stiffness modeling, analysis and comparison of a Biglide parallel grinder with two alternative modular parallelograms. It turns out that the Cartesian stiffness matrix of the manipulator has the property that it can be decoupled into two homogeneous matrices, correspondi...

  5. Identification and location tasks rely on different mental processes: a diffusion model account of validity effects in spatial cueing paradigms with emotional stimuli.

    Science.gov (United States)

    Imhoff, Roland; Lange, Jens; Germar, Markus

    2018-02-22

    Spatial cueing paradigms are popular tools to assess human attention to emotional stimuli, but different variants of these paradigms differ in what participants' primary task is. In one variant, participants indicate the location of the target (location task), whereas in the other they indicate the shape of the target (identification task). In the present paper we test the idea that although these two variants produce seemingly comparable cue validity effects on response times, they rest on different underlying processes. Across four studies (total N = 397; two in the supplement) using both variants and manipulating the motivational relevance of cue content, diffusion model analyses revealed that cue validity effects in location tasks are primarily driven by response biases, whereas the same effect rests on delay due to attention to the cue in identification tasks. Based on this, we predict and empirically support that a symmetrical distribution of valid and invalid cues would reduce cue validity effects in location tasks to a greater extent than in identification tasks. Across all variants of the task, we fail to replicate the effect of greater cue validity effects for arousing (vs. neutral) stimuli. We discuss the implications of these findings for best practice in spatial cueing research.

  6. Three-dimensional spin mapping of antiferromagnetic nanopyramids having spatially alternating surface anisotropy at room temperature.

    Science.gov (United States)

    Wang, Kangkang; Smith, Arthur R

    2012-11-14

    Antiferromagnets play a key role in modern spintronic devices owing to their ability to modify the switching behavior of adjacent ferromagnets via the exchange bias effect. Consequently, detailed measurements of the spin structure at antiferromagnetic interfaces and surfaces are highly desirable, not only for advancing technologies but also for enabling new insights into the underlying physics. Here using spin-polarized scanning tunneling microscopy at room-temperature, we reveal in three-dimensions an orthogonal spin structure on antiferromagnetic compound nanopyramids. Contrary to expected uniaxial anisotropy based on bulk properties, the atomic terraces are found to have alternating in-plane and out-of-plane magnetic anisotropies. The observed layer-wise alternation in anisotropy could have strong influences on future nanoscale spintronic applications.

  7. Vestibular Loss in Older Adults Is Associated with Impaired Spatial Navigation: Data from the Triangle Completion Task

    Directory of Open Access Journals (Sweden)

    Yanjun Xie

    2017-04-01

    Full Text Available BackgroundVestibular inputs have been shown to play a critical role in spatial navigation. In this study, we sought to evaluate whether vestibular loss due to aging contributes to impaired spatial navigation as measured by the triangle completion task (TCT.Materials and methodsWe recruited three types of participants: young controls <55 years of age, older controls ≥55 years of age, and older patients from a Neurotology Clinic with evidence of vestibular physiologic impairment but who did not have any known vestibular disorder. We performed the cervical vestibular-evoked myogenic potential to evaluate saccular function and video head impulse testing to quantify horizontal semicircular canal vestibulo-ocular reflex gain. To assess spatial navigation ability, we administered the TCT, in which participants were conveyed along two segments of a pre-drawn triangular path and instructed to complete the final segment independently. We measured the angle (degrees and distance (centimeters of deviation from the correct trajectory. We evaluated the influence of vestibular inputs on TCT performance.ResultsForty-eight adults participated in the study (mean age: 62.0 years; 52.1% females, including 9 young controls, 15 older controls, and 24 clinic patients. Clinic patients had the greatest distance of deviation (67.7 cm, followed by older controls (45.4 cm, then young controls (27.8 cm; p < 0.01. Similarly, clinic patients had greater rotational angles (22.1° compared to older (13.3° and younger controls (12.4°; p < 0.01. Following multivariate linear regression adjusting for demographic variables, loss of otolith function was associated with an 18.2 cm increase in distance of deviation (95% CI: 15.2–47.4 and a 9.2° increase in rotational angle (95% CI: 3.0–15.5. Abnormal semicircular canal function was associated with a 26.0 cm increase in distance of deviation (95% CI: 0.2–51.8 and a 10.8° increase in rotational angle

  8. On the physical problem of spatial dimensions: an alternative procedure to stability arguments

    International Nuclear Information System (INIS)

    Caruso, F.; Xavier, R.M.

    1986-01-01

    The three-dimensionality of space as a physical problem is discussed. Consideration on previous works is done, in which it is showed that the n-dimensional solar system can be stable only for n=3 and, from quantum mechanics, that this is the case also for hydrogen atons. Thus the epistemological consequences of the use of the stability postulate to derive spatial dimensionality is critically reviewed. The distinguished role of Maxwell's eletromagnetic theory in the determination of space dimensionality is stressed. 'Metric versus' 'topological' 'arguments are compared and shown to apply respectively to 'matter' and 'fields'. (G.D.F.) [pt

  9. Pre-weaning dietary iron deficiency impairs spatial learning and memory in the cognitive holeboard task in piglets

    Directory of Open Access Journals (Sweden)

    Alexandra eAntonides

    2015-10-01

    Full Text Available Iron deficiency (ID is the most common nutritional deficiency in humans, affecting more than two billion people worldwide. Early-life ID can lead to irreversible deficits in learning and memory. The pig represents a promising model animal for studying such deficits, because of its similarities to humans during early development. We investigated long-term effects of pre-weaning dietary iron deficiency in piglets on growth, blood parameters, cognitive performance and brain histology. Ten male sibling pairs of piglets were removed from the sow 4-6 days after birth. Ten piglets were given an iron dextran injection and were fed a control milk diet for 28 days (100 mg Fe/kg; their ten siblings were given a saline injection and fed an iron deficient milk diet (10 mg Fe/kg. Then, all piglets were fed a balanced commercial pig diet (190-240 mg Fe/kg. From 8 weeks of age, piglets were tested in a spatial cognitive holeboard task. In this task, 4 of 16 holes contain a hidden food reward, allowing measurement of working (short-term memory and reference (long-term memory (RM simultaneously. All piglets received 40-60 acquisition trials, followed by a 16-trial reversal phase. ID piglets showed permanently retarded growth and a strong decrease in blood iron parameters during dietary treatment. After treatment, ID piglets blood iron values restored to normal levels. In the holeboard task, ID piglets showed impaired RM learning during acquisition and reversal. Iron staining at necropsy at 12 weeks of age showed that ID piglets had fewer iron-containing cells in hippocampal regions CA1 and dentate gyrus. The number of iron-containing cells in CA3 correlated positively with acquisition RM performance for all animals. Our results support the hypothesis that early ID leads to lasting cognitive deficits. The piglet as a model animal, tested in the holeboard, can be useful in future research for assessing long-term cognitive effects of early-life diets or diet

  10. Selective deficit in spatial memory strategies contrast to intact response strategies in patients with schizophrenia spectrum disorders tested in a virtual navigation task.

    Science.gov (United States)

    Wilkins, Leanne K; Girard, Todd A; Konishi, Kyoko; King, Matthew; Herdman, Katherine A; King, Jelena; Christensen, Bruce; Bohbot, Veronique D

    2013-11-01

    Spatial memory is impaired among persons with schizophrenia (SCZ). However, different strategies may be used to solve most spatial memory and navigation tasks. This study investigated the hypothesis that participants with schizophrenia-spectrum disorders (SSD) would demonstrate differential impairment during acquisition and retrieval of target locations when using a hippocampal-dependent spatial strategy, but not a response strategy, which is more associated with caudate function. Healthy control (CON) and SSD participants were tested using the 4-on-8 virtual maze (4/8VM), a virtual navigation task designed to differentiate between participants' use of spatial and response strategies. Consistent with our predictions, SSD participants demonstrated a differential deficit such that those who navigated using a spatial strategy made more errors and took longer to locate targets. In contrast, SSD participants who spontaneously used a response strategy performed as well as CON participants. The differential pattern of spatial-memory impairment in SSD provides only indirect support for underlying hippocampal dysfunction. These findings emphasize the importance of considering individual strategies when investigating SSD-related memory and navigation performance. Future cognitive intervention protocols may harness SSD participants' intact ability to navigate using a response strategy and/or train the deficient ability to navigate using a spatial strategy to improve navigation and memory abilities in participants with SSD. Copyright © 2013 Wiley Periodicals, Inc.

  11. Alternative spatial allocation of suitable land for biofuel production in China

    DEFF Research Database (Denmark)

    Zhang, Jianjun; Chen, Yang; Rao, Yongheng

    2017-01-01

    How to select locations for biofuel production is still a critical consideration for balance of crop and biofuel productions as well as of energy consumption and environmental conservation. Biofuels are widely produced all over the world, but this practice in China is still at the initial stage....... Based on China's current stage on food security and changing biofuel demands, this paper selected agro-environmental and socio-economic factors of biofuel production, and simulated and spatially allocated areas suited for biofuel production under the two scenarios of planning-oriented scenario (Po......S) and biofuel-oriented scenario (BoS) by the target year 2020. It also estimated biofuel production potentials and zones across China's provinces. The results show that land suited for biofuel production is primarily located in Northwestern, Northern, Northeastern, Central and Southwestern China...

  12. The Effects of Adding Coordinate Axes To a Mental Rotations Task in Measuring Spatial Visualization Ability in Introductory Undergraduate Technical Graphics Courses.

    Science.gov (United States)

    Branoff, Ted

    1998-01-01

    Reports on a study to determine whether the presence of coordinate axes in a test of spatial-visualization ability affects scores and response times on a mental-rotations task for students enrolled in undergraduate introductory graphic communications classes. Based on Pavios's dual-coding theory. Contains 36 references. (DDR)

  13. The influence of spatial congruency and movement preparation time on saccade curvature in simultaneous and sequential dual-tasks.

    Science.gov (United States)

    Moehler, Tobias; Fiehler, Katja

    2015-11-01

    Saccade curvature represents a sensitive measure of oculomotor inhibition with saccades curving away from covertly attended locations. Here we investigated whether and how saccade curvature depends on movement preparation time when a perceptual task is performed during or before saccade preparation. Participants performed a dual-task including a visual discrimination task at a cued location and a saccade task to the same location (congruent) or to a different location (incongruent). Additionally, we varied saccade preparation time (time between saccade cue and Go-signal) and the occurrence of the discrimination task (during saccade preparation=simultaneous vs. before saccade preparation=sequential). We found deteriorated perceptual performance in incongruent trials during simultaneous task performance while perceptual performance was unaffected during sequential task performance. Saccade accuracy and precision were deteriorated in incongruent trials during simultaneous and, to a lesser extent, also during sequential task performance. Saccades consistently curved away from covertly attended non-saccade locations. Saccade curvature was unaffected by movement preparation time during simultaneous task performance but decreased and finally vanished with increasing movement preparation time during sequential task performance. Our results indicate that the competing saccade plan to the covertly attended non-saccade location is maintained during simultaneous task performance until the perceptual task is solved while in the sequential condition, in which the discrimination task is solved prior to the saccade task, oculomotor inhibition decays gradually with movement preparation time. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Middle-aged human apoE4 targeted-replacement mice show retention deficits on a wide range of spatial memory tasks.

    Science.gov (United States)

    Bour, Alexandra; Grootendorst, Jeannette; Vogel, Elise; Kelche, Christian; Dodart, Jean-Cosme; Bales, Kelly; Moreau, Pierre-Henri; Sullivan, Patrick M; Mathis, Chantal

    2008-11-21

    Apolipoprotein (apo) E4, one of three human apoE (h-apoE) isoforms, has been identified as a major genetic risk factor for Alzheimer's disease and for cognitive deficits associated with aging. However, the biological mechanisms involving apoE in learning and memory processes are unclear. A potential isoform-dependent role of apoE in cognitive processes was studied in human apoE targeted-replacement (TR) mice. These mice express either the human apoE3 or apoE4 gene under the control of endogenous murine apoE regulatory sequences, resulting in physiological expression of h-apoE in both a temporal and spatial pattern similar to humans. Male and female apoE3-TR, apoE4-TR, apoE-knockout and C57BL/6J mice (15-18 months) were tested with spatial memory and avoidance conditioning tasks. Compared to apoE3-TR mice, spatial memory in female apoE4-TR mice was impaired based on their poor performances in; (i) the probe test of the water-maze reference memory task, (ii) the water-maze working memory task and (iii) an active avoidance Y-maze task. Retention performance on a passive avoidance task was also impaired in apoE4-TR mice, but not in other genotypes. These deficits in both spatial and avoidance memory tasks may be related to the anatomical and functional abnormalities previously reported in the hippocampus and the amygdala of apoE4-TR mice. We conclude that the apoE4-TR mice provide an excellent model for understanding the mechanisms underlying apoE4-dependent susceptibility to cognitive decline.

  15. Spatial and stage-structured population model of the American crocodile for comparison of comprehensive Everglades Restoration Plan (CERP) alternatives

    Science.gov (United States)

    Green, Timothy W.; Slone, Daniel H.; Swain, Eric D.; Cherkiss, Michael S.; Lohmann, Melinda; Mazzotti, Frank J.; Rice, Kenneth G.

    2010-01-01

    As part of the U.S. Geological Survey Priority Ecosystems Science (PES) initiative to provide the ecological science required during Everglades restoration, we have integrated current regional hydrologic models with American crocodile (Crocodylus acutus) research and monitoring data to create a model that assesses the potential impact of Comprehensive Everglades Restoration Plan (CERP) efforts on the American crocodile. A list of indicators was created by the Restoration Coordination and Verification (RECOVER) component of CERP to help determine the success of interim restoration goals. The American crocodile was established as an indicator of the ecological condition of mangrove estuaries due to its reliance upon estuarine environments characterized by low salinity and adequate freshwater inflow. To gain a better understanding of the potential impact of CERP restoration efforts on the American crocodile, a spatially explicit crocodile population model has been created that has the ability to simulate the response of crocodiles to various management strategies for the South Florida ecosystem. The crocodile model uses output from the Tides and Inflows in the Mangroves of the Everglades (TIME) model, an application of the Flow and Transport in a Linked Overland/Aquifer Density Dependent System (FTLOADDS) simulator. TIME has the capability to link to the South Florida Water Management Model (SFWMM), which is the primary regional tool used to assess CERP restoration scenarios. A crocodile habitat suitability index and spatial parameter maps that reflect salinity, water depth, habitat, and nesting locations are used as driving functions to construct crocodile finite rate of increase maps under different management scenarios. Local stage-structured models are integrated with a spatial landscape grid to display crocodile movement behavior in response to changing environmental conditions. Restoration efforts are expected to affect salinity levels throughout the habitat of

  16. Stimulus- and state-dependence of systematic bias in spatial attention: additive effects of stimulus-size and time-on-task.

    Science.gov (United States)

    Benwell, Christopher S Y; Harvey, Monika; Gardner, Stephanie; Thut, Gregor

    2013-03-01

    Systematic biases in spatial attention are a common finding. In the general population, a systematic leftward bias is typically observed (pseudoneglect), possibly as a consequence of right hemisphere dominance for visuospatial attention. However, this leftward bias can cross-over to a systematic rightward bias with changes in stimulus and state factors (such as line length and arousal). The processes governing these changes are still unknown. Here we tested models of spatial attention as to their ability to account for these effects. To this end, we experimentally manipulated both stimulus and state factors, while healthy participants performed a computerized version of a landmark task. State was manipulated by time-on-task (>1 h) leading to increased fatigue and a reliable left- to rightward shift in spatial bias. Stimulus was manipulated by presenting either long or short lines which was associated with a shift of subjective midpoint from a reliable leftward bias for long to a more rightward bias for short lines. Importantly, we found time-on-task and line length effects to be additive suggesting a common denominator for line bisection across all conditions, which is in disagreement with models that assume that bisection decisions in long and short lines are governed by distinct processes (Magnitude estimation vs Global/local distinction). Our findings emphasize the dynamic rather than static nature of spatial biases in midline judgement. They are best captured by theories of spatial attention positing that spatial bias is flexibly modulated, and subject to inter-hemispheric balance which can change over time or conditions to accommodate task demands or reflect fatigue. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Inverse Transformation: Unleashing Spatially Heterogeneous Dynamics with an Alternative Approach to XPCS Data Analysis.

    Science.gov (United States)

    Andrews, Ross N; Narayanan, Suresh; Zhang, Fan; Kuzmenko, Ivan; Ilavsky, Jan

    2018-02-01

    X-ray photon correlation spectroscopy (XPCS), an extension of dynamic light scattering (DLS) in the X-ray regime, detects temporal intensity fluctuations of coherent speckles and provides scattering vector-dependent sample dynamics at length scales smaller than DLS. The penetrating power of X-rays enables probing dynamics in a broad array of materials with XPCS, including polymers, glasses and metal alloys, where attempts to describe the dynamics with a simple exponential fit usually fails. In these cases, the prevailing XPCS data analysis approach employs stretched or compressed exponential decay functions (Kohlrausch functions), which implicitly assume homogeneous dynamics. In this paper, we propose an alternative analysis scheme based upon inverse Laplace or Gaussian transformation for elucidating heterogeneous distributions of dynamic time scales in XPCS, an approach analogous to the CONTIN algorithm widely accepted in the analysis of DLS from polydisperse and multimodal systems. Using XPCS data measured from colloidal gels, we demonstrate the inverse transform approach reveals hidden multimodal dynamics in materials, unleashing the full potential of XPCS.

  18. Learning strategy preference of 5XFAD transgenic mice depends on the sequence of place/spatial and cued training in the water maze task.

    Science.gov (United States)

    Cho, Woo-Hyun; Park, Jung-Cheol; Chung, ChiHye; Jeon, Won Kyung; Han, Jung-Soo

    2014-10-15

    Learning strategy preference was assessed in 5XFAD mice, which carry 5 familial Alzheimer's disease (AD) mutations. Mice were sequentially trained in cued and place/spatial versions of the water maze task. After training, a strategy preference test was conducted in which mice were required to choose between the spatial location where the platform had previously been during the place/spatial training, and a visible platform in a new location. 5XFAD and non-transgenic control mice showed equivalent escape performance in both training tasks. However, in the strategy preference test, 5XFAD mice preferred a cued strategy relative to control mice. When the training sequence was presented in the reverse order (i.e., place/spatial training before cued training), 5XFAD mice showed impairments in place/spatial training, but no differences in cued training or in the strategy preference test comparing to control. Analysis of regional Aβ42 deposition in brains of 5XFAD mice showed that the hippocampus, which is involved in the place/spatial learning strategy, had the highest levels of Aβ42 and the dorsal striatum, which is involved in cued learning strategy, showed a small increase in Aβ42 levels. The effect of training protocol order on performance, and regional differences in Aβ42 deposition observed in 5XFAD mice, suggest differential functional recruitment of brain structures related to learning in healthy and AD individuals. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Bursts of occipital theta and alpha amplitude preceding alternation and repetition trials in a task-switching experiment

    NARCIS (Netherlands)

    Gladwin, T.E.; De Jong, Ritske

    The instantaneous amplitude of the theta and alpha bands of the electroencephalogram (EEG) was studied during preparation periods in a task-switching experiment. Subjects had to switch between tasks in which they were to respond to either the visual or the auditory component of the stimulus. 11-13

  20. Biomass supply from alternative cellulosic crops and crop residues: A spatially explicit bioeconomic modeling approach

    International Nuclear Information System (INIS)

    Egbendewe-Mondzozo, Aklesso; Swinton, Scott M.; Izaurralde, César R.; Manowitz, David H.; Zhang, Xuesong

    2011-01-01

    This paper introduces a spatially-explicit bioeconomic model for the study of potential cellulosic biomass supply. For biomass crops to begin to replace current crops, farmers must earn more from them than from current crops. Using weather, topographic and soil data, the terrestrial ecosystem model, EPIC, dynamically simulates multiple cropping systems that vary by crop rotation, tillage, fertilization and residue removal rate. EPIC generates predicted crop yield and environmental outcomes over multiple watersheds. These EPIC results are used to parameterize a regional profit-maximization mathematical programming model that identifies profitable cropping system choices. The bioeconomic model is calibrated to 2007–09 crop production in a 9-county region of southwest Michigan. A simulation of biomass supply in response to rising biomass prices shows that cellulosic residues from corn stover and wheat straw begin to be supplied at minimum delivered biomass:corn grain price ratios of 0.15 and 0.18, respectively. At the mean corn price of $162.6/Mg ($4.13 per bushel) at commercial moisture content during 2007–2009, these ratios correspond to stover and straw prices of $24 and $29 per dry Mg. Perennial bioenergy crops begin to be supplied at price levels 2–3 times higher. Average biomass transport costs to the biorefinery plant range from $6 to $20/Mg compared to conventional crop production practices in the area, biomass supply from annual crop residues increased greenhouse gas emissions and reduced water quality through increased nutrient loss. By contrast, perennial cellulosic biomass crop production reduced greenhouse gas emissions and improved water quality. -- Highlights: ► A new bioeconomic model predicts biomass supply and its environmental impacts. ► The model captures the opportunity cost of switching to new cellulosic crops. ► Biomass from crop residues is supplied at lower biomass price than cellulosic crops. ► Biomass from cellulosic crops has

  1. Postural tasks are associated with center of pressure spatial patterns of three-dimensional statokinesigrams in young and elderly healthy subjects.

    Science.gov (United States)

    Baracat, Patrícia Junqueira Ferraz; de Sá Ferreira, Arthur

    2013-12-01

    The present study investigated the association between postural tasks and center of pressure spatial patterns of three-dimensional statokinesigrams. Young (n=35; 27.0±7.7years) and elderly (n=38; 67.3±8.7years) healthy volunteers maintained an undisturbed standing position during postural tasks characterized by combined sensory (vision/no vision) and biomechanical challenges (feet apart/together). A method for the analysis of three-dimensional statokinesigrams based on nonparametric statistics and image-processing analysis was employed. Four patterns of spatial distribution were derived from ankle and hip strategies according to the quantity (single; double; multi) and location (anteroposterior; mediolateral) of high-density regions on three-dimensional statokinesigrams. Significant associations between postural task and spatial pattern were observed (young: gamma=0.548, p<.001; elderly: gamma=0.582, p<.001). Robustness analysis revealed small changes related to parameter choices for histogram processing. MANOVA revealed multivariate main effects for postural task [Wilks' Lambda=0.245, p<.001] and age [Wilks' Lambda=0.308, p<.001], with interaction [Wilks' Lambda=0.732, p<.001]. The quantity of high-density regions was positively correlated to stabilogram and statokinesigram variables (p<.05 or lower). In conclusion, postural tasks are associated with center of pressure spatial patterns and are similar in young and elderly healthy volunteers. Single-centered patterns reflected more stable postural conditions and were more frequent with complete visual input and a wide base of support. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Brain Activity Stimulated by Prism Adaptation Tasks Utilized for the Treatment of Unilateral Spatial Neglect: A Study with fNIRS

    Directory of Open Access Journals (Sweden)

    Hiroshi Taniguchi

    2012-01-01

    Full Text Available We investigated the neurological basis for efficacy of prism adaptation therapy, which is used for the treatment of poststroke unilateral spatial neglect (USN. Study subjects were 6 USN-positive (+, 6 USN-negative patients, and 6 healthy volunteer control subjects. USN was identified by the Behavioural Inattention Test (BIT. During the tasks, brain activity was assessed with fNIRS via changes in oxyHb concentration per unit length. There was no significant difference in the number of errors in the task between the 3 groups. However, in the USN(+ group there was a significantly greater reduction in oxyHb levels in the right parietal association cortex during the prism adaptation task than in the other 2 groups (<0.05. There was an immediate improvement in USN symptoms as well as a significant increase in oxyHb levels during the prism adaptation in the channels covering the right frontal and parietal lobes in 2 patients in the USN(+ group (<0.05. This result suggested that decreased activity in the right parietal association cortex, which is related to spatial perception, during the prism adaptation task and task-induced reorganization of the right frontal and parietal areas were involved in improvement in USN symptoms.

  3. Lateralized Contribution of Prefrontal Cortex in Controlling Task-Irrelevant Information during Verbal and Spatial Working Memory Tasks: rTMS Evidence

    Science.gov (United States)

    Sandrini, Marco; Rossini, Paolo Maria; Miniussi, Carlo

    2008-01-01

    The functional organization of working memory (WM) in the human prefrontal cortex remains unclear. The present study used repetitive transcranial magnetic stimulation (rTMS) to clarify the role of the dorsolateral prefrontal cortex (dlPFC) both in the types of information (verbal vs. spatial), and the types of processes (maintenance vs.…

  4. Effects of Dual-Tasks on Spatial-Temporal Parameters of Gait in Older Adults With Impaired Balance

    Directory of Open Access Journals (Sweden)

    Elaheh Azadian

    2016-04-01

    Conclusion: The results showed that the duration of double reliance and stance increase when walking with dual task than when normal walking. Therefore, in the elderly with poor balance, doing dual-task with walking could increase the risk of fall. With regard to increase in asymmetry in walking with dual-task, it seems that mutual harmony and symmetry is very sensitive to concurrent cognitive task. This asymmetry in the function of legs is considered a risk factor in falling. Thus, based on the results, walking of the elderly with poor balance needs better cognitive performance. Doing concurrent cognitive tasks could intervene with attention sources and consequently change the walking pattern. Therefore, we recommend that the older people with weak balance and prone to falling should refrain from cognitive dual-task during walking and focus on walking itself.   

  5. Differential cortical c-Fos and Zif-268 expression after object and spatial memory processing in a standard or episodic-like object recognition task

    Directory of Open Access Journals (Sweden)

    Flávio F Barbosa

    2013-08-01

    Full Text Available Episodic memory reflects the capacity to recollect what, where and when a specific event happened in an integrative manner. Animal studies have suggested that the medial temporal lobe and the medial pre-frontal cortex are important for episodic-like memory formation. The goal of present study was to evaluate whether there are different patterns of expression of the immediate early genes c-Fos and Zif-268 in these cortical areas after rats are exposed to object recognition tasks with different cognitive demands. Male rats were randomly assigned to five groups: home cage control (CTR-HC, empty open field (CTR-OF, open field with one object (CTR-OF + Obj, novel object recognition task (OR and episodic-like memory task (ELM and were killed one hour after the last behavioral procedure. Rats were able to discriminate the objects in the OR task. In the ELM task, rats showed spatial (but not temporal discrimination of the objects. We found an increase in the c-Fos expression in the dorsal dentate gyrus (DG and in the perirhinal cortex (PRh in the OR and ELM groups. The OR group also presented an increase of c-Fos expression in the medial prefrontal cortex (mPFC. Additionally, the OR and ELM groups had increased expression of Zif-268 in the mPFC. Moreover, Zif-268 was increased in the dorsal CA1 and perirhinal cortex only in the ELM group. In conclusion, the pattern of activation was different in tasks with different cognitive demands. Accordingly, correlation tests suggest the engagement of different neural networks in the object recognition tasks used. Specifically, perirhinal-dentate gyrus co-activation was detected after the what-where memory retrieval, but not after the novel object recognition task. Both regions correlated with the respective behavioral outcome. These findings can be helpful in the understanding of the neural networks underlying memory tasks with different cognitive demands.

  6. Comparison of proximally versus distally placed spatially distributed sequential stimulation electrodes in a dynamic knee extension task

    Directory of Open Access Journals (Sweden)

    Marco Laubacher

    2016-06-01

    Full Text Available Spatially distributed sequential stimulation (SDSS has demonstrated substantial power output and fatigue benefits compared to single electrode stimulation (SES in the application of functional electrical stimulation (FES. This asymmetric electrode setup brings new possibilities but also new questions since precise placement of the electrodes is one critical factor for good muscle activation. The aim of this study was to compare the power output, fatigue and activation properties of proximally versus distally placed SDSS electrodes in an isokinetic knee extension task simulating knee movement during recumbent cycling. M. vastus lateralis and medialis of seven able-bodied subjects were stimulated with rectangular bi-phasic pulses of constant amplitude of 40 mA and at an SDSS frequency of 35 Hz for 6 min on both legs with both setups (i.e. n=14. Torque was measured during knee-extension movement by a dynamometer at an angular velocity of 110 deg/s. Mean power, peak power and activation time were calculated and compared for the initial and final stimulation phases, together with an overall fatigue index. Power output values (Pmean, Ppeak were scaled to a standardised reference input pulse width of 100 μs (Pmean,s, Ppeak,s. The initial evaluation phase showed no significant differences between the two setups for all outcome measures. Ppeak and Ppeak,s were both significantly higher in the final phase for the distal setup (25.4 ± 8.1 W vs. 28.2 ± 6.2 W, p=0.0062 and 34.8 ± 9.5 W vs. 38.9 ± 6.7 W, p=0.021, respectively. With distal SDSS, there was modest evidence of higher Pmean and Pmean,s (p=0.071, p=0.14, respectively but of longer activation time (p=0.096. The rate of fatigue was similar for both setups. For practical FES applications, distal placement of the SDSS electrodes is preferable.

  7. Considering Alternate Futures to Classify Off-Task Behavior as Emotion Self-Regulation: A Supervised Learning Approach

    Science.gov (United States)

    Sabourin, Jennifer L.; Rowe, Jonathan P.; Mott, Bradford W.; Lester, James C.

    2013-01-01

    Over the past decade, there has been growing interest in real-time assessment of student engagement and motivation during interactions with educational software. Detecting symptoms of disengagement, such as off-task behavior, has shown considerable promise for understanding students' motivational characteristics during learning. In this paper, we…

  8. [Neuronal activity of monkey dorso-lateral premotor cortex during tasks of figure recognition guided motor sequence vs memorized spatial motor sequence].

    Science.gov (United States)

    Chen, Y C; Huang, F D; Chen, N H; Shou, J Y; Wu, L

    1998-04-01

    In the last 2-3 decades the role of the premotor cortex (PM) of monkey in memorized spatial sequential (MSS) movements has been amply investigated. However, it is as yet not known whether PM participates in the movement sequence behaviour guided by recognition of visual figures (i.e. the figure-recognition sequence, FRS). In the present work three monkeys were trained to perform both FRS and MSS tasks. Postmortem examination showed that 202 cells were in the dorso-lateral premotor cortex. Among 111 cells recorded during the two tasks, more than 50% changed their activity during the cue periods in either task. During the response period, the ratios of cells with changes of firing rate in both FRS and MSS were high and roughly equal to each other, while during the image period, the proportion in the FRS (83.7%) was significantly higher than that in the MSS (66.7%). Comparison of neuronal activities during same motor sequence of two different tasks showed that during the image periods PM neuronal activities were more closely related to the FRS task, while during the cue periods no difference could be found. Analysis of cell responses showed that the neurons with longer latency were much more in MSS than in FRS in either cue or image period. The present results indicate that the premotor cortex participates in FRS motor sequence as well as in MSS and suggest that the dorso-lateral PM represents another subarea in function shared by both FRS and MSS tasks. However, in view of the differences of PM neuronal responses in cue or image periods of FRS and MSS tasks, it seems likely that neural networks involved in FRS and MSS tasks are different.

  9. Retention and relearning of spatial delayed alternation in rats after ablation of the prefrontal or total non-prefrontal isocortex

    DEFF Research Database (Denmark)

    Wörtwein, Gitta; Mogensen, Jesper; Divac, Ivan

    1994-01-01

    Neurobiologi, præfrontal cortex, delayed alternation, funktionel genopretning, neocortex, rotte......Neurobiologi, præfrontal cortex, delayed alternation, funktionel genopretning, neocortex, rotte...

  10. Study of alternative strategies to the task clarification activity of the market-pull product development process model

    OpenAIRE

    Motte, Damien

    2009-01-01

    A very large majority of the current product development process models put forward in textbooks present a homogenous structure, what Ulrich & Eppinger [1] call the market-pull model, presented as a generic one, while other possible product development process models are merely seen as variants. This paper focuses on the task clarification and derived activities (mainly the systematic search for customer needs through market study and the supplementary development costs it entails) and in...

  11. Information Provision to the Visually Impaired in Alternative Formats in Nigeria: Are Public Libraries Up to the Task?

    Directory of Open Access Journals (Sweden)

    Adetoro, 'Niran

    2014-06-01

    Full Text Available Public libraries provide information to all persons and its users are the inhabitants of the community it serves. This may not be the reality in some cases as some category of persons may not be properly served by the public library. This study assesses the provision of information materials in alternative format, in terms of its availability, access and level of use by the visually impaired in public libraries in southwestern Nigeria. The study adopted survey research design. Four (4 public libraries in four states were purposively selected because they are the ones that provide alternative format for the use of a sizable number of the visually impaired. Complete enumeration was used to capture all the 166 registered users of the libraries through the use of observations checklist and interview schedule. Data from 69.2% of the 166 visually impaired persons that were interviewed, and the observations made were analyzed. The result reveals that alternative formats availability were inadequate and, e-resources were not available while access to formats and information desired by the users were limited. Braille is the most utilized format; audio materials and large prints were seldom used. The demand for alternative formats is high but it is not related to level of use of materials. Provision of information materials in alternative formats for the visually impaired in public libraries cannot support the needs of the visually impaired; it requires intervention from all stakeholders. The study recommends improved investment and funding for public libraries and services to persons with disabilities.

  12. Hippocampal-dependent memory in the plus-maze discriminative avoidance task: The role of spatial cues and CA1 activity.

    Science.gov (United States)

    Leão, Anderson H F F; Medeiros, André M; Apolinário, Gênedy K S; Cabral, Alícia; Ribeiro, Alessandra M; Barbosa, Flávio F; Silva, Regina H

    2016-05-01

    The plus-maze discriminative avoidance task (PMDAT) has been used to investigate interactions between aversive memory and an anxiety-like response in rodents. Suitable performance in this task depends on the activity of the basolateral amygdala, similar to other aversive-based memory tasks. However, the role of spatial cues and hippocampal-dependent learning in the performance of PMDAT remains unknown. Here, we investigated the role of proximal and distal cues in the retrieval of this task. Animals tested under misplaced proximal cues had diminished performance, and animals tested under both misplaced proximal cues and absent distal cues could not discriminate the aversive arm. We also assessed the role of the dorsal hippocampus (CA1) in this aversive memory task. Temporary bilateral inactivation of dorsal CA1 was conducted with muscimol (0.05 μg, 0.1 μg, and 0.2 μg) prior to the training session. While the acquisition of the task was not altered, muscimol impaired the performance in the test session and reduced the anxiety-like response in the training session. We also performed a spreading analysis of a fluorophore-conjugated muscimol to confirm selective inhibition of CA1. In conclusion, both distal and proximal cues are required to retrieve the task, with the latter being more relevant to spatial orientation. Dorsal CA1 activity is also required for aversive memory formation in this task, and interfered with the anxiety-like response as well. Importantly, both effects were detected by different parameters in the same paradigm, endorsing the previous findings of independent assessment of aversive memory and anxiety-like behavior in the PMDAT. Taken together, these findings suggest that the PMDAT probably requires an integration of multiple systems for memory formation, resembling an episodic-like memory rather than a pure conditioning behavior. Furthermore, the concomitant and independent assessment of emotionality and memory in rodents is relevant to

  13. The role of rewarding and novel events in facilitating memory persistence in a separate spatial memory task

    Science.gov (United States)

    Salvetti, Beatrice; Morris, Richard G.M.; Wang, Szu-Han

    2014-01-01

    Many insignificant events in our daily life are forgotten quickly but can be remembered for longer when other memory-modulating events occur before or after them. This phenomenon has been investigated in animal models in a protocol in which weak memories persist longer if exploration in a novel context is introduced around the time of memory encoding. This study aims to understand whether other types of rewarding or novel tasks, such as rewarded learning in a T-maze and novel object recognition, can also be effective memory-modulating events. Rats were trained in a delayed matching-to-place task to encode and retrieve food locations in an event arena. Weak encoding with only one food pellet at the sample location induced memory encoding but forgetting over 24 h. When this same weak encoding was followed by a rewarded task in a T-maze, the memory persisted for 24 h. Moreover, the same persistence of memory over 24 h could be achieved by exploration in a novel box or by a rewarded T-maze task after a “non-rewarded” weak encoding. When the one-pellet weak encoding was followed by novel object exploration, the memory did not persist at 24 h. Together, the results confirm that place encoding is possible without explicit reward, and that rewarded learning in a separate task lacking novelty can be an effective memory-modulating event. The behavioral and neurobiological implications are discussed. PMID:24429424

  14. Low-frequency rTMS in the superior parietal cortex affects the working memory in horizontal axis during the spatial task performance.

    Science.gov (United States)

    Ribeiro, Jéssica Alves; Marinho, Francisco Victor Costa; Rocha, Kaline; Magalhães, Francisco; Baptista, Abrahão Fontes; Velasques, Bruna; Ribeiro, Pedro; Cagy, Mauricio; Bastos, Victor Hugo; Gupta, Daya; Teixeira, Silmar

    2018-03-01

    Spatial working memory has been extensively investigated with different tasks, treatments, and analysis tools. Several studies suggest that low frequency of the repetitive transcranial magnetic stimulation (rTMS) applied to the parietal cortex may influence spatial working memory (SWM). However, it is not yet known if after low-frequency rTMS applied to the superior parietal cortex, according to Pz electroencephalography (EEG) electrode, would change the orientation interpretation about the vertical and horizontal axes coordinates in an SWM task. The current study aims at filling this gap and obtains a better understanding of the low-frequency rTMS effect in SWM. In this crossover study, we select 20 healthy subjects in two conditions (control and 1-Hz rTMS). The subjects performed an SWM task with two random coordinates. Our results presented that low-frequency rTMS applied over the superior parietal cortex may influence the SWM to lead to a larger distance of axes interception point (p low-frequency rTMS over the superior parietal cortex (SPC) changes the SWM performance, and it has more predominance in horizontal axis.

  15. Delayed-matching-to-place Task in a Dry Maze to Measure Spatial Working Memory in Mice.

    Science.gov (United States)

    Feng, Xi; Krukowski, Karen; Jopson, Timothy; Rosi, Susanna

    2017-07-05

    The delayed-matching-to-place (DMP) dry maze test is a variant of DMP water maze (Steele and Morris, 1999; Faizi et al. , 2012) which measures spatial working/episodic-like learning and memory that depends on both hippocampal and cortical functions (Wang and Morris, 2010; Euston et al. , 2012). Using this test we can detect normal aging related spatial working memory decline, as well as trauma induced working memory deficits. Furthermore, we recently reported that fractionated whole brain irradiation does not affect working memory in mice (Feng et al. , 2016). Here we describe the experimental setup and procedures of this behavioral test.

  16. A Male Advantage for Spatial and Object but Not Verbal Working Memory Using the N-Back Task

    Science.gov (United States)

    Lejbak, Lisa; Crossley, Margaret; Vrbancic, Mirna

    2011-01-01

    Sex-related differences have been reported for performance and neural substrates on some working memory measures that carry a high cognitive load, including the popular n-back neuroimaging paradigm. Despite some evidence of a sex effect on the task, the influence of sex on performance represents a potential confound in neuroimaging research. The…

  17. Resting-State Seed-Based Analysis: An Alternative to Task-Based Language fMRI and Its Laterality Index.

    Science.gov (United States)

    Smitha, K A; Arun, K M; Rajesh, P G; Thomas, B; Kesavadas, C

    2017-06-01

    Language is a cardinal function that makes human unique. Preservation of language function poses a great challenge for surgeons during resection. The aim of the study was to assess the efficacy of resting-state fMRI in the lateralization of language function in healthy subjects to permit its further testing in patients who are unable to perform task-based fMRI. Eighteen healthy right-handed volunteers were prospectively evaluated with resting-state fMRI and task-based fMRI to assess language networks. The laterality indices of Broca and Wernicke areas were calculated by using task-based fMRI via a voxel-value approach. We adopted seed-based resting-state fMRI connectivity analysis together with parameters such as amplitude of low-frequency fluctuation and fractional amplitude of low-frequency fluctuation (fALFF). Resting-state fMRI connectivity maps for language networks were obtained from Broca and Wernicke areas in both hemispheres. We performed correlation analysis between the laterality index and the z scores of functional connectivity, amplitude of low-frequency fluctuation, and fALFF. Pearson correlation analysis between signals obtained from the z score of fALFF and the laterality index yielded a correlation coefficient of 0.849 ( P laterality index yielded an R 2 value of 0.721, indicating that 72.1% of the variance in the laterality index of task-based fMRI could be predicted from the fALFF of resting-state fMRI. The present study demonstrates that fALFF can be used as an alternative to task-based fMRI for assessing language laterality. There was a strong positive correlation between the fALFF of the Broca area of resting-state fMRI with the laterality index of task-based fMRI. Furthermore, we demonstrated the efficacy of fALFF for predicting the laterality of task-based fMRI. © 2017 by American Journal of Neuroradiology.

  18. Differences in spatial working memory as a function of team sports expertise: the Corsi Block-tapping task in sport psychological assessment.

    Science.gov (United States)

    Furley, Philip; Memmert, Daniel

    2010-06-01

    Individual differences in visuospatial abilities were investigated in experienced basketball players compared with nonathletes. Most research shows that experts and novices do not differ on basic cognitive ability tests. Nevertheless, there are some equivocal findings indicating there are differences in basic cognitive abilities such as attention. The goal of the present research was to investigate team-ball athletes in regard to their visuospatial abilities. 112 male college students (54 basketball players, 58 nonathlete college students) were tested in their spatial capacity with the Corsi Block-tapping Task. No differences in spatial capacity were evident between basketball players and nonathlete college students. The results are discussed in the context of the expert performance approach and individual difference research.

  19. Anxiety-related biases in visual orienting and spatial motor response selection independently assessed by a probe-classification task

    NARCIS (Netherlands)

    Schrooten, M.G.S.; Smulders, F.T.Y.; Mogg, K.; Bradley, B.P.

    2012-01-01

    This dot-probe study assessed anxiety-related biases in visual attentional orienting and spatial motor response selection (motor attention) in high- and low-trait-anxious adults, and whether anxiety-related biases depend on response speed. Emotional-neutral word pairs appeared for 14 or 500 ms, with

  20. Real-life memory and spatial navigation in patients with focal epilepsy: ecological validity of a virtual reality supermarket task.

    Science.gov (United States)

    Grewe, P; Lahr, D; Kohsik, A; Dyck, E; Markowitsch, H J; Bien, C G; Botsch, M; Piefke, M

    2014-02-01

    Ecological assessment and training of real-life cognitive functions such as visual-spatial abilities in patients with epilepsy remain challenging. Some studies have applied virtual reality (VR) paradigms, but external validity of VR programs has not sufficiently been proven. Patients with focal epilepsy (EG, n=14) accomplished an 8-day program in a VR supermarket, which consisted of learning and buying items on a shopping list. Performance of the EG was compared with that of healthy controls (HCG, n=19). A comprehensive neuropsychological examination was administered. Real-life performance was investigated in a real supermarket. Learning in the VR supermarket was significantly impaired in the EG on different VR measures. Delayed free recall of products did not differ between the EG and the HCG. Virtual reality scores were correlated with neuropsychological measures of visual-spatial cognition, subjective estimates of memory, and performance in the real supermarket. The data indicate that our VR approach allows for the assessment of real-life visual-spatial memory and cognition in patients with focal epilepsy. The multimodal, active, and complex VR paradigm may particularly enhance visual-spatial cognitive resources. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Gaze-based rehearsal in children under 7: a developmental investigation of eye movements during a serial spatial memory task.

    Science.gov (United States)

    Morey, Candice C; Mareva, Silvana; Lelonkiewicz, Jaroslaw R; Chevalier, Nicolas

    2018-05-01

    The emergence of strategic verbal rehearsal at around 7 years of age is widely considered a major milestone in descriptions of the development of short-term memory across childhood. Likewise, rehearsal is believed by many to be a crucial factor in explaining why memory improves with age. This apparent qualitative shift in mnemonic processes has also been characterized as a shift from passive visual to more active verbal mnemonic strategy use, but no investigation of the development of overt spatial rehearsal has informed this explanation. We measured serial spatial order reconstruction in adults and groups of children 5-7 years old and 8-11 years old, while recording their eye movements. Children, particularly the youngest children, overtly fixated late-list spatial positions longer than adults, suggesting that younger children are less likely to engage in covert rehearsal during stimulus presentation than older children and adults. However, during retention the youngest children overtly fixated more of the to-be-remembered sequences than any other group, which is inconsistent with the idea that children do nothing to try to remember. Altogether, these data are inconsistent with the notion that children under 7 do not engage in any attempts to remember. They are most consistent with proposals that children's style of remembering shifts around age 7 from reactive cue-driven methods to proactive, covert methods, which may include cumulative rehearsal. © 2017 John Wiley & Sons Ltd.

  2. Contributions of Sensory Coding and Attentional Control to Individual Differences in Performance in Spatial Auditory Selective Attention Tasks.

    Science.gov (United States)

    Dai, Lengshi; Shinn-Cunningham, Barbara G

    2016-01-01

    Listeners with normal hearing thresholds (NHTs) differ in their ability to steer attention to whatever sound source is important. This ability depends on top-down executive control, which modulates the sensory representation of sound in the cortex. Yet, this sensory representation also depends on the coding fidelity of the peripheral auditory system. Both of these factors may thus contribute to the individual differences in performance. We designed a selective auditory attention paradigm in which we could simultaneously measure envelope following responses (EFRs, reflecting peripheral coding), onset event-related potentials (ERPs) from the scalp (reflecting cortical responses to sound) and behavioral scores. We performed two experiments that varied stimulus conditions to alter the degree to which performance might be limited due to fine stimulus details vs. due to control of attentional focus. Consistent with past work, in both experiments we find that attention strongly modulates cortical ERPs. Importantly, in Experiment I, where coding fidelity limits the task, individual behavioral performance correlates with subcortical coding strength (derived by computing how the EFR is degraded for fully masked tones compared to partially masked tones); however, in this experiment, the effects of attention on cortical ERPs were unrelated to individual subject performance. In contrast, in Experiment II, where sensory cues for segregation are robust (and thus less of a limiting factor on task performance), inter-subject behavioral differences correlate with subcortical coding strength. In addition, after factoring out the influence of subcortical coding strength, behavioral differences are also correlated with the strength of attentional modulation of ERPs. These results support the hypothesis that behavioral abilities amongst listeners with NHTs can arise due to both subcortical coding differences and differences in attentional control, depending on stimulus characteristics

  3. Contributions of sensory coding and attentional control to individual differences in performance in spatial auditory selective attention tasks

    Directory of Open Access Journals (Sweden)

    Lengshi Dai

    2016-10-01

    Full Text Available Listeners with normal hearing thresholds differ in their ability to steer attention to whatever sound source is important. This ability depends on top-down executive control, which modulates the sensory representation of sound in cortex. Yet, this sensory representation also depends on the coding fidelity of the peripheral auditory system. Both of these factors may thus contribute to the individual differences in performance. We designed a selective auditory attention paradigm in which we could simultaneously measure envelope following responses (EFRs, reflecting peripheral coding, onset event-related potentials from the scalp (ERPs, reflecting cortical responses to sound, and behavioral scores. We performed two experiments that varied stimulus conditions to alter the degree to which performance might be limited due to fine stimulus details vs. due to control of attentional focus. Consistent with past work, in both experiments we find that attention strongly modulates cortical ERPs. Importantly, in Experiment I, where coding fidelity limits the task, individual behavioral performance correlates with subcortical coding strength (derived by computing how the EFR is degraded for fully masked tones compared to partially masked tones; however, in this experiment, the effects of attention on cortical ERPs were unrelated to individual subject performance. In contrast, in Experiment II, where sensory cues for segregation are robust (and thus less of a limiting factor on task performance, inter-subject behavioral differences correlate with subcortical coding strength. In addition, after factoring out the influence of subcortical coding strength, behavioral differences are also correlated with the strength of attentional modulation of ERPs. These results support the hypothesis that behavioral abilities amongst listeners with normal hearing thresholds can arise due to both subcortical coding differences and differences in attentional control, depending on

  4. Neural correlates of the spatial and expectancy components of endogenous and stimulus-driven orienting of attention in the Posner task.

    Science.gov (United States)

    Doricchi, Fabrizio; Macci, Enrica; Silvetti, Massimo; Macaluso, Emiliano

    2010-07-01

    Voluntary orienting of visual attention is conventionally measured in tasks with predictive central cues followed by frequent valid targets at the cued location and by infrequent invalid targets at the uncued location. This implies that invalid targets entail both spatial reorienting of attention and breaching of the expected spatial congruency between cues and targets. Here, we used event-related functional magnetic resonance imaging (fMRI) to separate the neural correlates of the spatial and expectancy components of both endogenous orienting and stimulus-driven reorienting of attention. We found that during endogenous orienting with predictive cues, there was a significant deactivation of the right Temporal-Parietal Junction (TPJ). We also discovered that the lack of an equivalent deactivation with nonpredictive cues was matched to drop in attentional costs and preservation of attentional benefits. The right TPJ showed equivalent responses to invalid targets following predictive and nonpredictive cues. On the contrary, infrequent-unexpected invalid targets following predictive cues specifically activated the right Middle and Inferior Frontal Gyrus (MFG-IFG). Additional comparisons with spatially neutral trials demonstrated that, independently of cue predictiveness, valid targets activate the left TPJ, whereas invalid targets activate both the left and right TPJs. These findings show that the selective right TPJ activation that is found in the comparison between invalid and valid trials results from the reciprocal cancelling of the different activations that in the left TPJ are related to the processing of valid and invalid targets. We propose that left and right TPJs provide "matching and mismatching to attentional template" signals. These signals enable reorienting of attention and play a crucial role in the updating of the statistical contingency between cues and targets.

  5. Tau Depletion in APP Transgenic Mice Attenuates Task-Related Hyperactivation of the Hippocampus and Differentially Influences Locomotor Activity and Spatial Memory

    Directory of Open Access Journals (Sweden)

    Misato Yoshikawa

    2018-03-01

    Full Text Available Hippocampal hyperactivity, ascribed to amyloid β (Aβ-induced imbalances in neural excitation and inhibition, is found in patients with mild cognitive impairment, a prodromal stage of Alzheimer's disease (AD. To better understand the relationship between hippocampal hyperactivity and the molecular triggers of behavioral impairments in AD, we used Mn-enhanced MRI (MEMRI to assess neuronal activity after subjecting mice to a task requiring spatial learning and memory. Depletion of endogenous tau in an amyloid precursor protein (APP transgenic (J20 mouse line was shown to ameliorate hippocampal hyperactivity in J20 animals, tau depletion failed to reverse memory deficits associated with APP/Aβ overproduction. On the other hand, deletion of tau alleviated the hyperlocomotion displayed by APP transgenics, suggesting that the functional effects of Aβ-tau interactions reflect the temporal appearance of these molecules in individual brain areas.

  6. The role of spatial frequency information in the decoding of facial expressions of pain: a novel hybrid task.

    Science.gov (United States)

    Wang, Shan; Eccleston, Christopher; Keogh, Edmund

    2017-11-01

    Spatial frequency (SF) information contributes to the recognition of facial expressions, including pain. Low-SF encodes facial configuration and structure and often dominates over high-SF information, which encodes fine details in facial features. This low-SF preference has not been investigated within the context of pain. In this study, we investigated whether perpetual preference differences exist for low-SF and high-SF pain information. A novel hybrid expression paradigm was used in which 2 different expressions, one containing low-SF information and the other high-SF information, were combined in a facial hybrid. Participants are instructed to identify the core expression contained within the hybrid, allowing for the measurement of SF information preference. Three experiments were conducted (46 participants in each) that varied the expressions within the hybrid faces: respectively pain-neutral, pain-fear, and pain-happiness. In order to measure the temporal aspects of image processing, each hybrid image was presented for 33, 67, 150, and 300 ms. As expected, identification of pain and other expressions was dominated by low-SF information across the 3 experiments. The low-SF preference was largest when the presentation of hybrid faces was brief and reduced as the presentation duration increased. A sex difference was also found in experiment 1. For women, the low-SF preference was dampened by high-SF pain information, when viewing low-SF neutral expressions. These results not only confirm the role that SF information has in the recognition of pain in facial expressions but suggests that in some situations, there may be sex differences in how pain is communicated.

  7. Effect of reference frames and number of cues available on the spatial orientation of males and females in a virtual memory task.

    Science.gov (United States)

    Cánovas, Rosa; García, Rubén Fernández; Cimadevilla, Jose Manuel

    2011-01-01

    The aim of this study was to examine the influence of the number of cues and cue location in human spatial learning. To assess their importance, subjects performed variants of a virtual task called "The Boxes Room". Participants were trained to locate, in a computer-generated environment with 16 boxes, the rewarded boxes through 8 trials. In experiment I, the number of distal cues available was zero, one, two or the standard arrangement (seven cues). In experiment II, place navigation was compared based on distal landmarks (extra-maze cues placed on the walls) and proximal landmarks (proximal cues placed between the boxes). The results of experiment I demonstrated that one cue in the room is enough to obtain a good performance in the task. Experiment II showed that groups using proximal cues were slower and less accurate than groups using distal cues. In addition, our data suggest that men are better navigators than women, as they found the rewarded boxes sooner and committed fewer errors in both studies. These results indicate that performance can change depending on the number and location of available cues. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Low and high gamma oscillations in rat ventral striatum have distinct relationships to behavior, reward, and spiking activity on a learned spatial decision task

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    Matthijs A A Van Der Meer

    2009-06-01

    Full Text Available Local field potential (LFP oscillations in the brain reflect organization thought to be important for perception, attention, movement, and memory. In the basal ganglia, including dorsal striatum, dysfunctional LFP states are associated with Parkinson’s disease, while in healthy subjects, dorsal striatal LFPs have been linked to decision-making processes. However, LFPs in ventral striatum have been less studied. We report that in rats running a spatial decision task, prominent gamma-50 (45-55 Hz and gamma-80 (70-85 Hz oscillations in ventral striatum had distinct relationships to behavior, task events, and spiking activity. Gamma-50 power increased sharply following reward delivery and before movement initiation, while in contrast, gamma-80 power ramped up gradually to reward locations. Gamma-50 power was low and contained little structure during early learning, but rapidly developed a stable pattern, while gamma-80 power was initially high before returning to a stable level within a similar timeframe. Putative fast-spiking interneurons (FSIs showed phase, firing rate, and coherence relationships with gamma-50 and gamma-80, indicating that the observed LFP patterns are locally relevant. Furthermore, in a number of FSIs such relationships were specific to gamma-50 or gamma-80, suggesting that partially distinct FSI populations mediate the effects of gamma-50 and gamma-80.

  9. Negative effects of chronic oral chlorpromazine and olanzapine treatment on the performance of tasks designed to assess spatial learning and working memory in rats.

    Science.gov (United States)

    Terry, A V; Warner, S E; Vandenhuerk, L; Pillai, A; Mahadik, S P; Zhang, G; Bartlett, M G

    2008-10-28

    Learning potential and memory capacity are factors that strongly predict the level of rehabilitation and the long-term functional outcome in patients with schizophrenia. Unfortunately, however, the effects of antipsychotic drugs (i.e. the primary treatments for schizophrenia) on these components of cognition are unclear, particularly when they are administered chronically (i.e. a standard clinical practice). In this rodent study we evaluated the effects of different time periods (ranging from 2 weeks to 6 months) of oral treatment with the first generation antipsychotic chlorpromazine (10.0 mg/kg/day), or the second generation antipsychotic olanzapine (10.0 mg/kg/day) on the repeated acquisition of a water maze task (i.e. a method of assessing spatial learning potential in a repeated testing format). We assessed locomotor function (in an open field) and employed a radial arm maze (RAM) task to assess antipsychotic effects (5.0 and 10.0 mg/kg/day doses) on spatial working memory during the treatment period between 15 days and 2 months. Finally, we conducted experiments using liquid chromatography/tandem mass spectrometry (LC-MS/MS) to evaluate the therapeutic relevance of our method of drug delivery (oral administration in drinking water). In the water maze experiments, both antipsychotics were associated with impairments in acquisition in the earlier test sessions that could eventually be overcome with repeated testing while olanzapine also impaired retention in probe trials. Both antipsychotics were also associated with impairments in delayed non-match-to-position trials in the RAM and some impairments of motor function (especially in the case of olanzapine) as indicated by slightly reduced swim speeds in the water maze and decreased activity in some components of the open field assessment. Finally, LC-MS/MS studies indicated that the method of antipsychotic administration generated clinically relevant plasma levels in the rat. These animal data indicate that

  10. Effects of tree size and spatial distribution on growth of ponderosa pine forests under alternative management scenarios

    Science.gov (United States)

    C.W. Woodall; C.E. Fiedler; R.E. McRoberts

    2009-01-01

    Forest ecosystems may be actively managed toward heterogeneous stand structures to provide both economic (e.g., wood production and carbon credits) and environmental benefits (e.g., invasive pest resistance). In order to facilitate wider adoption of possibly more sustainable forest stand structures, defining growth expectations among alternative management scenarios is...

  11. Efeitos de duas modalidades tutoriais para a criança tutora em tarefas espaciais Effects of two tutorial modalities on tutor children in spatial tasks

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    Irene Franciscato

    2006-01-01

    Full Text Available O estudo investiga efeitos da tutoria para o tutor, na aprendizagem de noções espaciais, em duas modalidades: explicação oral e explicação oral com demonstração. Participaram 40 crianças de 8 a 9 anos, em três grupos experimentais e um grupo controle. A pesquisa teve delineamento experimental, com pré-teste e pós-testes. No pré-teste e pós-testes 1 e 2 foram aplicadas duas provas de noções espaciais. A tarefa experimental consistiu na realização do jogo do parking em três condições: crianças sozinhas, crianças em díades na modalidade explicação oral ou na modalidade explicação oral com demonstração. Os resultados mostraram que a tutoria favoreceu a aprendizagem das noções espaciais para a criança tutora, com vantagem para a modalidade explicação oral com demonstração. Foram identificadas variações nos progressos alcançados pelos tutores nas duas modalidades tutoriais. São feitas considerações sobre as vantagens da tutoria no campo educacional.The study concerns the effects of tutoring on tutor children, on the learning of spatial notions, in two tutorship modalities, oral explanation and oral explanation with demonstration. Subjects were 40 children aged 8 to 9 years old, randomly assigned to three experimental groups and a control group. The study design is experimental, with pre-test and post-test. Two spatial tasks were employed as pre-test and post-tests (1 and 2. The experimental task consisted in a parking game carried out under three conditions: children alone, children in pairs for both oral explanation and oral explanation with demonstration. Results showed that tutor's learning on the focused spatial notions was favored by tutorship especially under the oral explanation with demonstration condition. Some variations on the tutor's progress were also identified on both modalities. The results provide some grounds on which tutorship may be debated in the educational field.

  12. Prediction of human observer performance in a 2-alternative forced choice low-contrast detection task using channelized Hotelling observer: Impact of radiation dose and reconstruction algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Yu Lifeng; Leng Shuai; Chen Lingyun; Kofler, James M.; McCollough, Cynthia H. [Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States); Carter, Rickey E. [Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota 55905 (United States)

    2013-04-15

    Purpose: Efficient optimization of CT protocols demands a quantitative approach to predicting human observer performance on specific tasks at various scan and reconstruction settings. The goal of this work was to investigate how well a channelized Hotelling observer (CHO) can predict human observer performance on 2-alternative forced choice (2AFC) lesion-detection tasks at various dose levels and two different reconstruction algorithms: a filtered-backprojection (FBP) and an iterative reconstruction (IR) method. Methods: A 35 Multiplication-Sign 26 cm{sup 2} torso-shaped phantom filled with water was used to simulate an average-sized patient. Three rods with different diameters (small: 3 mm; medium: 5 mm; large: 9 mm) were placed in the center region of the phantom to simulate small, medium, and large lesions. The contrast relative to background was -15 HU at 120 kV. The phantom was scanned 100 times using automatic exposure control each at 60, 120, 240, 360, and 480 quality reference mAs on a 128-slice scanner. After removing the three rods, the water phantom was again scanned 100 times to provide signal-absent background images at the exact same locations. By extracting regions of interest around the three rods and on the signal-absent images, the authors generated 21 2AFC studies. Each 2AFC study had 100 trials, with each trial consisting of a signal-present image and a signal-absent image side-by-side in randomized order. In total, 2100 trials were presented to both the model and human observers. Four medical physicists acted as human observers. For the model observer, the authors used a CHO with Gabor channels, which involves six channel passbands, five orientations, and two phases, leading to a total of 60 channels. The performance predicted by the CHO was compared with that obtained by four medical physicists at each 2AFC study. Results: The human and model observers were highly correlated at each dose level for each lesion size for both FBP and IR. The

  13. Prediction of human observer performance in a 2-alternative forced choice low-contrast detection task using channelized Hotelling observer: Impact of radiation dose and reconstruction algorithms

    International Nuclear Information System (INIS)

    Yu Lifeng; Leng Shuai; Chen Lingyun; Kofler, James M.; McCollough, Cynthia H.; Carter, Rickey E.

    2013-01-01

    Purpose: Efficient optimization of CT protocols demands a quantitative approach to predicting human observer performance on specific tasks at various scan and reconstruction settings. The goal of this work was to investigate how well a channelized Hotelling observer (CHO) can predict human observer performance on 2-alternative forced choice (2AFC) lesion-detection tasks at various dose levels and two different reconstruction algorithms: a filtered-backprojection (FBP) and an iterative reconstruction (IR) method. Methods: A 35 × 26 cm 2 torso-shaped phantom filled with water was used to simulate an average-sized patient. Three rods with different diameters (small: 3 mm; medium: 5 mm; large: 9 mm) were placed in the center region of the phantom to simulate small, medium, and large lesions. The contrast relative to background was −15 HU at 120 kV. The phantom was scanned 100 times using automatic exposure control each at 60, 120, 240, 360, and 480 quality reference mAs on a 128-slice scanner. After removing the three rods, the water phantom was again scanned 100 times to provide signal-absent background images at the exact same locations. By extracting regions of interest around the three rods and on the signal-absent images, the authors generated 21 2AFC studies. Each 2AFC study had 100 trials, with each trial consisting of a signal-present image and a signal-absent image side-by-side in randomized order. In total, 2100 trials were presented to both the model and human observers. Four medical physicists acted as human observers. For the model observer, the authors used a CHO with Gabor channels, which involves six channel passbands, five orientations, and two phases, leading to a total of 60 channels. The performance predicted by the CHO was compared with that obtained by four medical physicists at each 2AFC study. Results: The human and model observers were highly correlated at each dose level for each lesion size for both FBP and IR. The Pearson's product

  14. Spatial variations in food web structures with alternative stable states: evidence from stable isotope analysis in a large eutrophic lake

    Science.gov (United States)

    Li, Yunkai; Zhang, Yuying; Xu, Jun; Zhang, Shuo

    2018-03-01

    Food web structures are well known to vary widely among ecosystems. Moreover, many food web studies of lakes have generally attempted to characterize the overall food web structure and have largely ignored internal spatial and environmental variations. In this study, we hypothesize that there is a high degree of spatial heterogeneity within an ecosystem and such heterogeneity may lead to strong variations in environmental conditions and resource availability, in turn resulting in different trophic pathways. Stable carbon and nitrogen isotopes were employed for the whole food web to describe the structure of the food web in different sub-basins within Taihu Lake. This lake is a large eutrophic freshwater lake that has been intensively managed and highly influenced by human activities for more than 50 years. The results show significant isotopic differences between basins with different environmental characteristics. Such differences likely result from isotopic baseline differences combining with a shift in food web structure. Both are related to local spatial heterogeneity in nutrient loading in waters. Such variation should be explicitly considered in future food web studies and ecosystem-based management in this lake ecosystem.

  15. Spatial variations in food web structures with alternative stable states: evidence from stable isotope analysis in a large eutrophic lake

    Science.gov (United States)

    Li, Yunkai; Zhang, Yuying; Xu, Jun; Zhang, Shuo

    2017-05-01

    Food web structures are well known to vary widely among ecosystems. Moreover, many food web studies of lakes have generally attempted to characterize the overall food web structure and have largely ignored internal spatial and environmental variations. In this study, we hypothesize that there is a high degree of spatial heterogeneity within an ecosystem and such heterogeneity may lead to strong variations in environmental conditions and resource availability, in turn resulting in different trophic pathways. Stable carbon and nitrogen isotopes were employed for the whole food web to describe the structure of the food web in different sub-basins within Taihu Lake. This lake is a large eutrophic freshwater lake that has been intensively managed and highly influenced by human activities for more than 50 years. The results show significant isotopic differences between basins with different environmental characteristics. Such differences likely result from isotopic baseline differences combining with a shift in food web structure. Both are related to local spatial heterogeneity in nutrient loading in waters. Such variation should be explicitly considered in future food web studies and ecosystem-based management in this lake ecosystem.

  16. Errors on interrupter tasks presented during spatial and verbal working memory performance are linearly linked to large-scale functional network connectivity in high temporal resolution resting state fMRI.

    Science.gov (United States)

    Magnuson, Matthew Evan; Thompson, Garth John; Schwarb, Hillary; Pan, Wen-Ju; McKinley, Andy; Schumacher, Eric H; Keilholz, Shella Dawn

    2015-12-01

    The brain is organized into networks composed of spatially separated anatomical regions exhibiting coherent functional activity over time. Two of these networks (the default mode network, DMN, and the task positive network, TPN) have been implicated in the performance of a number of cognitive tasks. To directly examine the stable relationship between network connectivity and behavioral performance, high temporal resolution functional magnetic resonance imaging (fMRI) data were collected during the resting state, and behavioral data were collected from 15 subjects on different days, exploring verbal working memory, spatial working memory, and fluid intelligence. Sustained attention performance was also evaluated in a task interleaved between resting state scans. Functional connectivity within and between the DMN and TPN was related to performance on these tasks. Decreased TPN resting state connectivity was found to significantly correlate with fewer errors on an interrupter task presented during a spatial working memory paradigm and decreased DMN/TPN anti-correlation was significantly correlated with fewer errors on an interrupter task presented during a verbal working memory paradigm. A trend for increased DMN resting state connectivity to correlate to measures of fluid intelligence was also observed. These results provide additional evidence of the relationship between resting state networks and behavioral performance, and show that such results can be observed with high temporal resolution fMRI. Because cognitive scores and functional connectivity were collected on nonconsecutive days, these results highlight the stability of functional connectivity/cognitive performance coupling.

  17. Dopaminergic and serotonergic modulation of persistent behaviour in the reinforced spatial alternation model of obsessive-compulsive disorder.

    Science.gov (United States)

    Kontis, Dimitris; Boulougouris, Vasileios; Papakosta, Vasiliki Maria; Kalogerakou, Stamatina; Papadopoulos, Socrates; Poulopoulou, Cornelia; Papadimitriou, George N; Tsaltas, Eleftheria

    2008-11-01

    We have proposed rewarded T-maze alternation as a model of obsessive-compulsive disorder (OCD): the serotonin agonist m-chlorophenylpiperazine (mCPP) increments persistence therein, while chronic pretreatment with selective serotonin reuptake inhibitor (SSRI fluoxetine) but not benzodiazepine or desipramine abolishes mCPP effects. However, we noted that acute SSRI administration also causes transient persistence increase, counteracted by mCPP pretreatment. This study (a) further explores the cross-tolerance between fluoxetine and mCPP and (b) extends the model by investigating its sensitivity to dopaminergic manipulations (D2, 3 agonism--quinpirole). In both experiments, baseline and drug testing were carried out under daily T-maze alternation training. Exp. 1: Matched group (n = 8) pairs of rats received one of the following 20-day pretreatments (daily intraperitoneal administration): (1) saline, (2) low-dose fluoxetine (2.5 mg/kg), (3) low-dose mCPP (0.5 mg/kg) or (4) combined fluoxetine + mCPP. One group per pretreatment then received a 4-day challenge with high-dose fluoxetine (10 mg/kg), the other with high-dose mCPP (2.5 mg/kg). Exp. 2: One group (n = 12) of rats received 20-day treatment with saline, another with quinpirole (0.5 mg/kg). Exp. 1: Saline and low-dose mCPP- or fluoxetine-pretreated animals showed significant persistence increases under both challenges, while combined low-dose fluoxetine + mCPP pretreatment afforded full protection from either challenge. Exp. 2: Quinpirole significantly increased directional persistence after 13 administration days. These results establish the sensitivity of the rewarded alternation OCD model to D2, 3 receptor activation, thereby extending its profile of pharmacological isomorphism with OCD. Furthermore, they suggest a common mechanism of action of an SSRI and a serotonin agonist in the control of directional persistence.

  18. Effect of computerized cognitive training with virtual spatial navigation task during bed rest immobilization and recovery on vascular function: A pilot study

    Directory of Open Access Journals (Sweden)

    Goswami N

    2015-02-01

    Full Text Available Nandu Goswami,1 Voyko Kavcic,2 Uros Marusic,3 Bostjan Simunic,3 Andreas Rössler,1 Helmut Hinghofer-Szalkay,1 Rado Pisot3 1Institute of Physiology, Medical University of Graz, Graz, Austria; 2Institute of Gerontology, Wayne State University, Detroit, MI, USA; 3Institute for Kinesiology Research, University of Primorska, Ankaran, Slovenia Abstract: We investigated the effects of bed rest (BR immobilization, with and without computerized cognitive training with virtual spatial navigation task (CCT, on vascular endothelium on older subjects. The effects of 14-day BR immobilization in healthy older males (n=16 of ages 53–65 years on endothelial function were studied using EndoPAT®, a noninvasive and user-independent method. From the group of 16 older men, 8 randomly received CCT during the BR, using virtual navigation tasks in a virtual environment with joystick device. In all the cases, EndoPAT assessments were done at pre- and post-BR immobilization as well as following 28 days of ambulatory recovery. The EndoPAT index increased from 1.53±0.09 (mean ± standard error of the mean at baseline to 1.61±0.16 following immobilization (P=0.62 in the group with CCT. The EndoPAT index decreased from 2.06±0.13 (mean ± standard error of the mean at baseline to 1.70±0.09 at the last day of BR study, day 14 (BR14 (P=0.09 in the control group. Additionally, there were no statistically significant differences between BR14 and at 28 days of follow-up (rehabilitation program (R28. Our results show a trend of immobilization in older persons affecting the vasoconstrictory endothelial response. As the control subjects had a greater increase in EndoPAT index after R28 (+0.018 compared to subjects who had cognitive training (+0.11 (calculated from the first day of BR study, it is possible that cognitive training during BR does not improve endothelial function but rather contributes to slowing down the impairment of endothelial function. Finally, our results

  19. Functional Dissociation of Confident and Not-Confident Errors in the Spatial Delayed Response Task Demonstrates Impairments in Working Memory Encoding and Maintenance in Schizophrenia

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    Jutta S. Mayer

    2018-05-01

    Full Text Available Even though extensively investigated, the nature of working memory (WM deficits in patients with schizophrenia (PSZ is not yet fully understood. In particular, the contribution of different WM sub-processes to the severe WM deficit observed in PSZ is a matter of debate. So far, most research has focused on impaired WM maintenance. By analyzing different types of errors in a spatial delayed response task (DRT, we have recently demonstrated that incorrect yet confident responses (which we labeled as false memory errors rather than incorrect/not-confident responses reflect failures of WM encoding, which was also impaired in PSZ. In the present study, we provide further evidence for a functional dissociation between confident and not-confident errors by manipulating the demands on WM maintenance, i.e., the length over which information has to be maintained in WM. Furthermore, we investigate whether these functionally distinguishable WM processes are impaired in PSZ. Twenty-four PSZ and 24 demographically matched healthy controls (HC performed a spatial DRT in which the length of the delay period was varied between 1, 2, 4, and 6 s. In each trial, participants also rated their level of response confidence. Across both groups, longer delays led to increased rates of incorrect/not-confident responses, while incorrect/confident responses were not affected by delay length. This functional dissociation provides additional support for our proposal that false memory errors (i.e., confident errors reflect problems at the level of WM encoding, while not-confident errors reflect failures of WM maintenance. Schizophrenic patients showed increased numbers of both confident and not-confident errors, suggesting that both sub-processes of WM—encoding and maintenance—are impaired in schizophrenia. Combined with the delay length-dependent functional dissociation, we propose that these impairments in schizophrenic patients are functionally distinguishable.

  20. Modulations of eye movement patterns by spatial filtering during the learning and testing phases of an old/new face recognition task.

    Science.gov (United States)

    Lemieux, Chantal L; Collin, Charles A; Nelson, Elizabeth A

    2015-02-01

    In two experiments, we examined the effects of varying the spatial frequency (SF) content of face images on eye movements during the learning and testing phases of an old/new recognition task. At both learning and testing, participants were presented with face stimuli band-pass filtered to 11 different SF bands, as well as an unfiltered baseline condition. We found that eye movements varied significantly as a function of SF. Specifically, the frequency of transitions between facial features showed a band-pass pattern, with more transitions for middle-band faces (≈5-20 cycles/face) than for low-band (≈20 cpf) ones. These findings were similar for the learning and testing phases. The distributions of transitions across facial features were similar for the middle-band, high-band, and unfiltered faces, showing a concentration on the eyes and mouth; conversely, low-band faces elicited mostly transitions involving the nose and nasion. The eye movement patterns elicited by low, middle, and high bands are similar to those previous researchers have suggested reflect holistic, configural, and featural processing, respectively. More generally, our results are compatible with the hypotheses that eye movements are functional, and that the visual system makes flexible use of visuospatial information in face processing. Finally, our finding that only middle spatial frequencies yielded the same number and distribution of fixations as unfiltered faces adds more evidence to the idea that these frequencies are especially important for face recognition, and reveals a possible mediator for the superior performance that they elicit.

  1. In vivo polymerization of poly(3,4-ethylenedioxythiophene) in the living rat hippocampus does not cause a significant loss of performance in a delayed alternation task

    Science.gov (United States)

    Ouyang, Liangqi; Shaw, Crystal L.; Kuo, Chin-chen; Griffin, Amy L.; Martin, David C.

    2014-04-01

    After extended implantation times, traditional intracortical neural probes exhibit a foreign-body reaction characterized by a reactive glial sheath that has been associated with increased system impedance and signal deterioration. Previously, we have proposed that the local in vivo polymerization of an electronically and ionically conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), might help to rebuild charge transport pathways across the glial scar between the device and surrounding parenchyma (Richardson-Burns et al 2007 J. Neural Eng. 4 L6-13). The EDOT monomer can be delivered via a microcannula/electrode system into the brain tissue of living animals followed by direct electrochemical polymerization, using the electrode itself as a source of oxidative current. In this study, we investigated the long-term effect of local in vivo PEDOT deposition on hippocampal neural function and histology. Rodent subjects were trained on a hippocampus-dependent task, delayed alternation (DA), and implanted with the microcannula/electrode system in the hippocampus. The animals were divided into four groups with different delay times between the initial surgery and the electrochemical polymerization: (1) control (no polymerization), (2) immediate (polymerization within 5 min of device implantation), (3) early (polymerization within 3-4 weeks after implantation) and (4) late (polymerization 7-8 weeks after polymerization). System impedance at 1 kHz was recorded and the tissue reactions were evaluated by immunohistochemistry. We found that under our deposition conditions, PEDOT typically grew at the tip of the electrode, forming an ˜500 µm cloud in the tissue. This is much larger than the typical width of the glial scar (˜150 µm). After polymerization, the impedance amplitude near the neurologically important frequency of 1 kHz dropped for all the groups; however, there was a time window of 3-4 weeks for an optimal decrease in impedance. For all surgery

  2. Brain Oscillatory and Hemodynamic Activity in a Bimanual Coordination Task Following Transcranial Alternating Current Stimulation (tACS): A Combined EEG-fNIRS Study.

    Science.gov (United States)

    Berger, Alisa; Pixa, Nils H; Steinberg, Fabian; Doppelmayr, Michael

    2018-01-01

    Motor control is associated with synchronized oscillatory activity at alpha (8-12 Hz) and beta (12-30 Hz) frequencies in a cerebello-thalamo-cortical network. Previous studies demonstrated that transcranial alternating current stimulation (tACS) is capable of entraining ongoing oscillatory activity while also modulating motor control. However, the modulatory effects of tACS on both motor control and its underlying electro- and neurophysiological mechanisms remain ambiguous. Thus, the purpose of this study was to contribute to gathering neurophysiological knowledge regarding tACS effects by investigating the after-effects of 10 Hz tACS and 20 Hz tACS at parietal brain areas on bimanual coordination and its concurrent oscillatory and hemodynamic activity. Twenty-four right-handed healthy volunteers (12 females) aged between 18 and 30 ( M = 22.35 ± 3.62) participated in the study and performed a coordination task requiring bimanual movements. Concurrent to bimanual motor training, participants received either 10 Hz tACS, 20 Hz tACS or a sham stimulation over the parietal cortex (at P3/P4 electrode positions) for 20 min via small gel electrodes (3,14 cm 2 Ag/AgCl, amperage = 1 mA). Before and three time-points after tACS (immediately, 30 min and 1 day), bimanual coordination performance was assessed. Oscillatory activities were measured by electroencephalography (EEG) and hemodynamic changes were examined using functional near-infrared spectroscopy (fNIRS). Improvements of bimanual coordination performance were not differently between groups, thus, no tACS-specific effect on bimanual coordination performance emerged. However, physiological measures during the task revealed significant increases in parietal alpha activity immediately following 10 Hz tACS and 20 Hz tACS which were accompanied by significant decreases of Hboxy concentration in the right hemispheric motor cortex compared to the sham group. Based on the physiological responses, we conclude that t

  3. Brain Oscillatory and Hemodynamic Activity in a Bimanual Coordination Task Following Transcranial Alternating Current Stimulation (tACS: A Combined EEG-fNIRS Study

    Directory of Open Access Journals (Sweden)

    Alisa Berger

    2018-04-01

    Full Text Available Motor control is associated with synchronized oscillatory activity at alpha (8–12 Hz and beta (12–30 Hz frequencies in a cerebello-thalamo-cortical network. Previous studies demonstrated that transcranial alternating current stimulation (tACS is capable of entraining ongoing oscillatory activity while also modulating motor control. However, the modulatory effects of tACS on both motor control and its underlying electro- and neurophysiological mechanisms remain ambiguous. Thus, the purpose of this study was to contribute to gathering neurophysiological knowledge regarding tACS effects by investigating the after-effects of 10 Hz tACS and 20 Hz tACS at parietal brain areas on bimanual coordination and its concurrent oscillatory and hemodynamic activity. Twenty-four right-handed healthy volunteers (12 females aged between 18 and 30 (M = 22.35 ± 3.62 participated in the study and performed a coordination task requiring bimanual movements. Concurrent to bimanual motor training, participants received either 10 Hz tACS, 20 Hz tACS or a sham stimulation over the parietal cortex (at P3/P4 electrode positions for 20 min via small gel electrodes (3,14 cm2 Ag/AgCl, amperage = 1 mA. Before and three time-points after tACS (immediately, 30 min and 1 day, bimanual coordination performance was assessed. Oscillatory activities were measured by electroencephalography (EEG and hemodynamic changes were examined using functional near-infrared spectroscopy (fNIRS. Improvements of bimanual coordination performance were not differently between groups, thus, no tACS-specific effect on bimanual coordination performance emerged. However, physiological measures during the task revealed significant increases in parietal alpha activity immediately following 10 Hz tACS and 20 Hz tACS which were accompanied by significant decreases of Hboxy concentration in the right hemispheric motor cortex compared to the sham group. Based on the physiological responses, we conclude that

  4. The Convergence in Spatial Tasks

    Directory of Open Access Journals (Sweden)

    Vladimir P. Kulagin

    2013-01-01

    Full Text Available The article reveals the problem of convergence of direct and inverse problems in Earth Sciences, describes the features and application of these problems, discloses analytical features of direct and inverse problems. The convergence criteria and conditions for convergence were presented. This work is supported by the Grant of the Government of the Russian Federation for support of scientific research, implemented under the supervision of leading scientists in Russian institutions of higher education in the field "Space Research and Technologies" in 2011–2013.

  5. Segregating Top-Down Selective Attention from Response Inhibition in a Spatial Cueing Go/NoGo Task: An ERP and Source Localization Study.

    Science.gov (United States)

    Hong, Xiangfei; Wang, Yao; Sun, Junfeng; Li, Chunbo; Tong, Shanbao

    2017-08-29

    Successfully inhibiting a prepotent response tendency requires the attentional detection of signals which cue response cancellation. Although neuroimaging studies have identified important roles of stimulus-driven processing in the attentional detection, the effects of top-down control were scarcely investigated. In this study, scalp EEG was recorded from thirty-two participants during a modified Go/NoGo task, in which a spatial-cueing approach was implemented to manipulate top-down selective attention. We observed classical event-related potential components, including N2 and P3, in the attended condition of response inhibition. While in the ignored condition of response inhibition, a smaller P3 was observed and N2 was absent. The correlation between P3 and CNV during the foreperiod suggested an inhibitory role of P3 in both conditions. Furthermore, source analysis suggested that P3 generation was mainly localized to the midcingulate cortex, and the attended condition showed increased activation relative to the ignored condition in several regions, including inferior frontal gyrus, middle frontal gyrus, precentral gyrus, insula and uncus, suggesting that these regions were involved in top-down attentional control rather than inhibitory processing. Taken together, by segregating electrophysiological correlates of top-down selective attention from those of response inhibition, our findings provide new insights in understanding the neural mechanisms of response inhibition.

  6. Alternative methods for disposal of low-level radioactive wastes. Task 2c: technical requirements for earth mounded concrete bunker disposal of low-level radioactive waste. Volume 4

    International Nuclear Information System (INIS)

    Miller, W.O.; Bennett, R.D.

    1985-10-01

    The study reported herein contains the results of Task 2c (Technical Requirements for Earth Mounded Concrete Bunker Disposal of Low-Level Radioactive Waste) of a four-task study entitled ''Criteria for Evaluating Engineered Facilities''. The overall objective of this study is to ensure that the criteria needed to evaluate five alternative low-level radioactive waste (LLW) disposal methods are available to potential license applicants. The earth mounded concrete bunker disposal alternative is one of several methods that may be proposed for disposal of low-level radioactive waste. The name of this alternative is descriptive of the disposal method used in France at the Centre de la Manche. Experience gained with this method at the Centre is described, including unit operations and features and components. Some improvements to the French system are recommended herein, including the use of previous backfill around monoliths and extending the limits of a low permeability surface layer. The applicability of existing criteria developed for near-surface disposal (10 CFR Part 61 Subpart D) to the earth mounded concrete bunker disposal method, as assessed in Task 1, are reassessed herein. With minor qualifications, these criteria were found to be applicable in the reassessment. These conclusions differ slightly from the Task 1 findings

  7. Task Switching in a Hierarchical Task Structure: Evidence for the Fragility of the Task Repetition Benefit

    Science.gov (United States)

    Lien, Mei-Ching; Ruthruff, Eric

    2004-01-01

    This study examined how task switching is affected by hierarchical task organization. Traditional task-switching studies, which use a constant temporal and spatial distance between each task element (defined as a stimulus requiring a response), promote a flat task structure. Using this approach, Experiment 1 revealed a large switch cost of 238 ms.…

  8. 5-HT2C receptor involvement in the control of persistence in the reinforced spatial alternation animal model of obsessive-compulsive disorder.

    Science.gov (United States)

    Papakosta, Vassiliki-Maria; Kalogerakou, Stamatina; Kontis, Dimitris; Anyfandi, Eleni; Theochari, Eirini; Boulougouris, Vasileios; Papadopoulos, Sokrates; Panagis, George; Tsaltas, Eleftheria

    2013-04-15

    The serotonergic system is implicated in the pathophysiology of obsessive-compulsive disorder (OCD). However, the distinct role of serotonin (5-HT) receptor subtypes remains unclear. This study investigates the contribution of 5-HT2A and 5-HT2C receptors in the modulation of persistence in the reinforced spatial alternation model of OCD. Male Wistar rats were assessed for spontaneous and pharmacologically induced (by m-chlorophenylpiperazine: mCPP) directional persistence in the reinforced alternation OCD model. Systemic administration of mCPP (non-specific 5-HT agonist, 2.5mg/kg), M100907 (selective 5-HT2A receptor antagonist, 0.08 mg/kg), SB242084 (selective 5-HT2C receptor antagonist, 0.5 mg/kg) and vehicle was used. Experiment 1 investigated M100907 and SB242084 effects in animals spontaneously exhibiting high and low persistence during the early stages of alternation training. Experiment 2 investigated M100900 and SB242084 effects on mCPP-induced persistence. Under the regime used in Experiment 1, 5-HT2A or 5-HT2C receptor antagonism did not affect spontaneous directional persistence in either high or low persistence groups. In Experiment 2, 5-HT2C but not 5-HT2A receptor antagonism significantly reduced, but did not abolish, mCPP-induced directional persistence. These findings suggest that 5-HT2C but not 5-HT2A receptors contribute to the modulation of mCPP-induced persistent behaviour, raising the possibility that the use of 5-HT2C antagonists may have a therapeutic value in OCD. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Executive functioning in preschool children: performance on A-not-B and other delayed response format tasks.

    Science.gov (United States)

    Espy, K A; Kaufmann, P M; McDiarmid, M D; Glisky, M L

    1999-11-01

    The A-not-B (AB) task has been hypothesized to measure executive/frontal lobe function; however, the developmental and measurement characteristics of this task have not been investigated. Performances on AB and comparison tasks adapted from developmental and neuroscience literature was examined in 117 preschool children (ages 23-66 months). Age significantly predicted performance on AB, Delayed Alternation, Spatial Reversal, Color Reversal, and Self-Control tasks. A four-factor analytic model best fit task performance data. AB task indices loaded on two factors with measures from the Self-Control and Delayed Alternation tasks, respectively. AB indices did not load with those from the reversal tasks despite similarities in task administration and presumed cognitive demand (working memory). These results indicate that AB is sensitive to individual differences in age-related performance in preschool children and suggest that AB performance is related to both working memory and inhibition processes in this age range.

  10. Supporting Alternative Strategies for Learning Chemical Applications of Group Theory

    Science.gov (United States)

    Southam, Daniel C.; Lewis, Jennifer E.

    2013-01-01

    A group theory course for chemists was taught entirely with process oriented guided inquiry learning (POGIL) to facilitate alternative strategies for learning. Students completed a test of one aspect of visuospatial aptitude to determine their individual approaches to solving spatial tasks, and were sorted into groups for analysis on the basis of…

  11. Differential Long-Term Effects of Haloperidol and Risperidone on the Acquisition and Performance of Tasks of Spatial Working and Short-Term Memory and Sustained Attention in Rats

    Science.gov (United States)

    Hutchings, Elizabeth J.; Waller, Jennifer L.

    2013-01-01

    A common feature of the neuropsychiatric disorders for which antipsychotic drugs are prescribed is cognitive dysfunction, yet the effects of long-term antipsychotic treatment on cognition are largely unknown. In the current study, we evaluated the effects of long-term oral treatment with the first-generation antipsychotic haloperidol (1.0 and 2.0 mg/kg daily) and the second-generation antipsychotic risperidone (1.25 and 2.5 mg/kg daily) on the acquisition and performance of two radial-arm maze (RAM) tasks and a five-choice serial reaction-time task (5C-SRTT) in rats during days 15–60 and 84–320 days of treatment, respectively. In the RAM, neither antipsychotic significantly affected the acquisition or performance of a spatial win shift or a delayed non–match-to-position task. Conversely, in the rats administered 5C-SRTT, haloperidol was associated with profound deficits in performance, and the subjects were not able to progress through all stages of task acquisition. Depending on the dose, risperidone was associated with a greater number of trials to meet specific performance criteria during task acquisition compared with vehicle-treated controls; however, most subjects were eventually able to achieve all levels of task acquisition. Both haloperidol and risperidone also increased the number of perseverative and time-out responses during certain stages of task acquisition, and the response and reward latencies were slightly higher than controls during several stages of the study. These results in rats suggest that while long-term treatment with haloperidol or risperidone may not significantly affect spatial working or short-term memory, both antipsychotics can (depending on dose) impair sustained attention, decrease psychomotor speed, increase compulsive-type behaviors, and impair cognitive flexibility. PMID:24042161

  12. Differential long-term effects of haloperidol and risperidone on the acquisition and performance of tasks of spatial working and short-term memory and sustained attention in rats.

    Science.gov (United States)

    Hutchings, Elizabeth J; Waller, Jennifer L; Terry, Alvin V

    2013-12-01

    A common feature of the neuropsychiatric disorders for which antipsychotic drugs are prescribed is cognitive dysfunction, yet the effects of long-term antipsychotic treatment on cognition are largely unknown. In the current study, we evaluated the effects of long-term oral treatment with the first-generation antipsychotic haloperidol (1.0 and 2.0 mg/kg daily) and the second-generation antipsychotic risperidone (1.25 and 2.5 mg/kg daily) on the acquisition and performance of two radial-arm maze (RAM) tasks and a five-choice serial reaction-time task (5C-SRTT) in rats during days 15-60 and 84-320 days of treatment, respectively. In the RAM, neither antipsychotic significantly affected the acquisition or performance of a spatial win shift or a delayed non-match-to-position task. Conversely, in the rats administered 5C-SRTT, haloperidol was associated with profound deficits in performance, and the subjects were not able to progress through all stages of task acquisition. Depending on the dose, risperidone was associated with a greater number of trials to meet specific performance criteria during task acquisition compared with vehicle-treated controls; however, most subjects were eventually able to achieve all levels of task acquisition. Both haloperidol and risperidone also increased the number of perseverative and time-out responses during certain stages of task acquisition, and the response and reward latencies were slightly higher than controls during several stages of the study. These results in rats suggest that while long-term treatment with haloperidol or risperidone may not significantly affect spatial working or short-term memory, both antipsychotics can (depending on dose) impair sustained attention, decrease psychomotor speed, increase compulsive-type behaviors, and impair cognitive flexibility.

  13. Identifying the spatial and temporal variability of economic opportunity costs to promote the adoption of alternative land uses in grain growing agricultural areas: an Australian example.

    Science.gov (United States)

    Lyle, G; Bryan, B A; Ostendorf, B

    2015-05-15

    Grain growers face many future challenges requiring them to adapt their land uses to changing economic, social and environmental conditions. To understand where to make on ground changes without significant negative financial repercussions, high resolution information on income generation over time is required. We propose a methodology which utilises high resolution yield data collected with precision agriculture (PA) technology, gross margin financial analysis and a temporal standardisation technique to highlight the spatial and temporal consistency of farm income. On three neighbouring farms in Western Australia, we found non-linear relationships between income and area. Spatio-temporal analysis on one farm over varying seasons found that between 37 and 49% (1082-1433ha) of cropping area consistently produced above the selected income thresholds and 43-32% (936-1257ha) regularly produced below selected thresholds. Around 20% of area showed inconsistent temporal variation in income generation. Income estimated from these areas represents the income forgone if a land use change is undertaken (the economic opportunity cost) and the average costs varied spatially from $190±114/ha to $560±108/ha depending on what scenario was chosen. The interaction over space and time showed the clustering of areas with similar values at a resolution where growers make input decisions. This new evidence suggests that farm area could be managed with two strategies: (a) one that maximises grain output using PA management in temporally stable areas which generate moderate to high income returns and (b) one that proposes land use change in low and inconsistent income returning areas where the financial returns from an alternative land use may be comparable. The adoption of these strategies can help growers meet the demand for agricultural output and offer income diversity and adaptive capacity to deal with the future challenges to agricultural production. Copyright © 2015 Elsevier Ltd

  14. Piped water consumption in Ghana: A case study of temporal and spatial patterns of clean water demand relative to alternative water sources in rural small towns.

    Science.gov (United States)

    Kulinkina, Alexandra V; Kosinski, Karen C; Liss, Alexander; Adjei, Michael N; Ayamgah, Gilbert A; Webb, Patrick; Gute, David M; Plummer, Jeanine D; Naumova, Elena N

    2016-07-15

    Continuous access to adequate quantities of safe water is essential for human health and socioeconomic development. Piped water systems (PWSs) are an increasingly common type of water supply in rural African small towns. We assessed temporal and spatial patterns in water consumption from public standpipes of four PWSs in Ghana in order to assess clean water demand relative to other available water sources. Low water consumption was evident in all study towns, which manifested temporally and spatially. Temporal variability in water consumption that is negatively correlated with rainfall is an indicator of rainwater preference when it is available. Furthermore, our findings show that standpipes in close proximity to alternative water sources such as streams and hand-dug wells suffer further reductions in water consumption. Qualitative data suggest that consumer demand in the study towns appears to be driven more by water quantity, accessibility, and perceived aesthetic water quality, as compared to microbiological water quality or price. In settings with chronic under-utilization of improved water sources, increasing water demand through household connections, improving water quality with respect to taste and appropriateness for laundry, and educating residents about health benefits of using piped water should be prioritized. Continued consumer demand and sufficient revenue generation are important attributes of a water service that ensure its function over time. Our findings suggest that analyzing water consumption of existing metered PWSs in combination with qualitative approaches may enable more efficient planning of community-based water supplies and support sustainable development. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. The Spatial Pattern and Interactions of Woody Plants on the Temperate Savanna of Inner Mongolia, China: The Effects of Alternating Seasonal Grazing-Mowing Regimes.

    Directory of Open Access Journals (Sweden)

    Xiao Wang

    Full Text Available Ulmus pumila tree-dominated temperate savanna, which is distributed widely throughout the forest-steppe ecotone on the Mongolian Plateau, is a relatively stable woody-herbaceous complex ecosystem in northern China. Relatively more attention has been paid to the degradation of typical steppe areas, whereas less focus has been placed on the succession of this typical temperate savanna under the present management regime. In this study, we established 3 sample plots 100 m×100 m in size along a gradient of fixed distances from one herder's stationary site and then surveyed all the woody plants in these plots. A spatial point pattern analysis was employed to clarify the spatial distribution and interaction of these woody plants. The results indicated that old U. pumila trees (DBH ≥ 20 cm showed a random distribution and that medium U. pumila trees (5 cm ≤ DBH < 20 cm showed an aggregated distribution at a smaller scale and a random distribution at a larger scale; few or no juvenile trees (DBH < 5 cm were present, and seedlings (without DBH formed aggregations in all 3 plots. These findings can be explained by an alternate seasonal grazing-mowing regime (exclosure in summer, mowing in autumn and grazing in winter and spring; the shrubs in all 3 plots exist along a grazing gradient that harbors xerophytic and mesophytic shrubs. Of these shrubs, xerophytic shrubs show significant aggregation at a smaller scale (0-5.5 m, whereas mesophytic shrubs show significant aggregation at a larger scale (0-25 m, which may be the result of the dual effects of grazing pressure and climate change. Medium trees and seedlings significantly facilitate the distributions of xerophytic shrubs and compete significantly with mesophytic shrubs due to differences in water use strategies. We conclude that the implementation of an alternative grazing-mowing regime results in xerophytic shrub encroachment or existence, breaking the chain of normal succession in a U. pumila

  16. Multimedia Design Principles in the Psychomotor Domain: The Effect of Multimedia and Spatial Contiguity on Students' Learning of Basic Life Support with Task Cards

    Science.gov (United States)

    Iserbyt, Peter; Mols, Liesbet; Elen, Jan; Behets, Daniel

    2012-01-01

    This study adds to the literature by introducing multimedia research in the psychomotor area. In this study, 87 freshman students in pedagogy used task cards to learn Basic Life Support (BLS), a psychomotor skill consisting of nine lifesaving actions to be performed in a specific order. Task cards are printed materials and are often implemented…

  17. Mapping of the Underlying Neural Mechanisms of Maintenance and Manipulation in Visuo-Spatial Working Memory Using An n-back Mental Rotation Task: A Functional Magnetic Resonance Imaging Study.

    Science.gov (United States)

    Lamp, Gemma; Alexander, Bonnie; Laycock, Robin; Crewther, David P; Crewther, Sheila G

    2016-01-01

    Mapping of the underlying neural mechanisms of visuo-spatial working memory (WM) has been shown to consistently elicit activity in right hemisphere dominant fronto-parietal networks. However to date, the bulk of neuroimaging literature has focused largely on the maintenance aspect of visuo-spatial WM, with a scarcity of research into the aspects of WM involving manipulation of information. Thus, this study aimed to compare maintenance-only with maintenance and manipulation of visuo-spatial stimuli (3D cube shapes) utilizing a 1-back task while functional magnetic resonance imaging (fMRI) scans were acquired. Sixteen healthy participants (9 women, M = 23.94 years, SD = 2.49) were required to perform the 1-back task with or without mentally rotating the shapes 90° on a vertical axis. When no rotation was required (maintenance-only condition), a right hemispheric lateralization was revealed across fronto-parietal areas. However, when the task involved maintaining and manipulating the same stimuli through 90° rotation, activation was primarily seen in the bilateral parietal lobe and left fusiform gyrus. The findings confirm that the well-established right lateralized fronto-parietal networks are likely to underlie simple maintenance of visuo-spatial stimuli. The results also suggest that the added demand of manipulation of information maintained online appears to require further neural recruitment of functionally related areas. In particular mental rotation of visuospatial stimuli required bilateral parietal areas, and the left fusiform gyrus potentially to maintain a categorical or object representation. It can be concluded that WM is a complex neural process involving the interaction of an increasingly large network.

  18. Inhibitory control and visuo-spatial reversibility in Piaget’s seminal number conservation task: A high-density ERP study.

    Directory of Open Access Journals (Sweden)

    Gregoire eBorst

    2013-12-01

    Full Text Available The present high-density ERP study on 13 adults aimed to determine whether number conservation relies on the ability to inhibit the overlearned length-equals-number strategy and then imagine the shortening of the row that was lengthened. Participants performed the number-conservation task and, after the EEG session, the mental imagery task. In the number-conservation task, first two rows with the same number of tokens and the same length were presented on a computer screen (COV condition and then, the tokens in one of the two rows were spread apart (INT condition. Participants were instructed to determine whether the two rows had an identical number of tokens. In the mental imagery task, two rows with different lengths but the same number of tokens were presented and participants were instructed to imagine the tokens in the longer row aligning with the tokens in the shorter row. In the number-conservation task, we found that the amplitudes of the centro-parietal N2 and fronto-central P3 were higher in the INT than in the COV conditions. In addition, the differences in response times between the two conditions were correlated with the differences in the amplitudes of the fronto-central P3. In light of previous results reported on the number-conservation task in adults, the present results suggest that inhibition might be necessary to succeed the number-conservation task in adults even when the transformation of the length of one of the row is displayed. Finally, we also reported correlations between the speed at which participants could imagine the shortening of one of the row in the mental imagery task, the speed at which participants could determine that the two rows had the same number of tokens after the tokens in one of the row were spread apart and the latency of the late positive parietal component in the number-conservation task. Therefore, performing the number-conservation task might involve mental transformation processes in adults.

  19. A virtual reality task based on animal research – spatial learning and memory in patients after the first episode of schizophrenia

    Czech Academy of Sciences Publication Activity Database

    Fajnerová, Iveta; Rodriguez, M.; Levčík, David; Konrádová, L.; Mikoláš, P.; Brom, C.; Stuchlík, Aleš; Vlček, Kamil; Horáček, J.

    2014-01-01

    Roč. 8, May 27 (2014), s. 157 ISSN 1662-5153 R&D Projects: GA MZd(CZ) NT13386 Grant - others:GA MZd(CZ) NT14291; GA MZd(CZ) NT13843 Institutional support: RVO:67985823 Keywords : schizophrenia * spatial navigation * learning and memory * virtual reality environment * cognitive deficit * Morris Water Maze (MWM) * psychotic disorders * spatial behavior Subject RIV: FH - Neurology Impact factor: 3.270, year: 2014

  20. Caffeine improves anticipatory processes in task switching

    NARCIS (Netherlands)

    Tieges, Zoe; Snel, Jan; Kok, Albert; Wijnen, Jasper G.; Lorist, Monicque M.; Ridderinkhof, K. Richard

    We studied the effects of moderate amounts of caffeine on task switching and task maintenance using mixed-task (AABB) blocks, in which participants alternated predictably between two tasks, and single-task (AAAA, BBBB) blocks. Switch costs refer to longer reaction times (RT) on task switch trials

  1. Overnight social isolation in pigs decreases salivary cortisol but does not impair spatial learning and memory or performance in a decision making task

    Directory of Open Access Journals (Sweden)

    F. Josef evan der Staay

    2016-01-01

    Full Text Available Pigs in modern farming practice may be exposed to a number of stressors, including social stressors such as mixing or isolation. This may potentially affect both cognitive abilities and stress physiology of the animals. We tested the hypothesis that overnight social isolation in pigs impairs performance in a cognitive Holeboard (HB task (Experiment 1 and the Pig Gambling Task (PGT (Experiment 2, a decision making task inspired by the Iowa Gambling Task. In addition, we tested the effect of overnight social isolation on salivary cortisol levels. A within-subjects approach was used in which performance in the two behavioral tasks and cortisol levels were first determined during normal social housing, followed by performance and cortisol levels after experiencing stress induced by overnight social isolation. A total of nineteen female pigs with a birthweight closest to their respective litter average was selected from 10 different litters and placed in two pens after weaning. Following habituation, pigs were trained in the HB task, starting at 10 weeks of age. Then, the pigs were isolated overnight, five individuals per night, at 15, 16 and 17 weeks of age. Between these three isolations, social housing and training in the HB continued. Starting 6 weeks after the end of the HB experiment, at approximately 23 weeks of age, the pigs were trained in the PGT. The effects of overnight social isolation on performance in this task were assessed once, when the pigs were 25 weeks old. Salivary cortisol was measured from samples collected 15 minutes after the start of isolation and at the end of the isolation period, and compared to baseline values collected before the start of social isolation. Our results did not confirm the hypothesis that isolation impaired HB performance and decision making in the PGT. Unexpectedly, overnight social isolation decreased cortisol levels below baseline values, an effect that was not associated with changes in performance

  2. Overnight Social Isolation in Pigs Decreases Salivary Cortisol but Does Not Impair Spatial Learning and Memory or Performance in a Decision-Making Task.

    Science.gov (United States)

    van der Staay, F Josef; Schoonderwoerd, Annelieke J; Stadhouders, Bo; Nordquist, Rebecca E

    2015-01-01

    Pigs in modern farming practice may be exposed to a number of stressors, including social stressors such as mixing or isolation. This may potentially affect both cognitive abilities and stress physiology of the animals. We tested the hypothesis that overnight social isolation in pigs impairs performance in a cognitive holeboard (HB) task (Experiment 1) and the Pig Gambling Task (PGT) (Experiment 2), a decision-making task inspired by the Iowa Gambling Task. In addition, we tested the effect of overnight social isolation on salivary cortisol levels. A within-subjects approach was used in which performance in the two behavioral tasks and cortisol levels were first determined during normal social housing, followed by performance and cortisol levels after experiencing stress induced by overnight social isolation. A total of 19 female pigs with a birth weight closest to their respective litter average was selected from 10 different litters and placed in two pens after weaning. Following habituation, pigs were trained in the HB task, starting at 10 weeks of age. Then, the pigs were isolated overnight, five individuals per night, at 15, 16, and 17 weeks of age. Between these three isolations, social housing and training in the HB continued. Starting 6 weeks after the end of the HB experiment, at approximately 23 weeks of age, the pigs were trained in the PGT. The effects of overnight social isolation on performance in this task were assessed once, when the pigs were 25 weeks old. Salivary cortisol was measured from samples collected 15 min after the start of isolation and at the end of the isolation period and compared to baseline values collected before the start of social isolation. Our results did not confirm the hypothesis that isolation impaired HB performance and decision-making in the PGT. Unexpectedly, overnight social isolation decreased cortisol levels below baseline values, an effect that was not associated with changes in performance of the

  3. Defining Elemental Imitation Mechanisms: A Comparison of Cognitive and Motor-Spatial Imitation Learning across Object- and Computer-Based Tasks

    Science.gov (United States)

    Subiaul, Francys; Zimmermann, Laura; Renner, Elizabeth; Schilder, Brian; Barr, Rachel

    2016-01-01

    During the first 5 years of life, the versatility, breadth, and fidelity with which children imitate change dramatically. Currently, there is no model to explain what underlies such significant changes. To that end, the present study examined whether task-independent but domain-specific--elemental--imitation mechanism explains performance across…

  4. The effects of task difficulty and resource requirements on attention strategies

    Science.gov (United States)

    King, Teresa

    1991-01-01

    The patterns of attention strategies for task difficulty/resource tasks for which experimental results are presented and analyzed support the hypothesis that subjects may adopt an alternating (rather than concurrent one) when compelled to do so by either the size or the complexity of a visual display. According to the multiple resource model, if subjects had been performing the two tasks concurrently, the cost of this strategy would have been shown by a decrement in the spatial format, rather than the verbal format, due to competition for the same resource. Subjects may apply different strategies as a function of task difficulty and/or resource demand.

  5. Stress hormones receptors in the amygdala mediate the effects of stress on the consolidation, but not the retrieval, of a non aversive spatial task.

    Directory of Open Access Journals (Sweden)

    Amir Segev

    Full Text Available This study examined the effects of the arousal level of the rat and exposure to a behavioral stressor on acquisition, consolidation and retrieval of a non-aversive hippocampal-dependent learning paradigm, the object location task. Learning was tested under two arousal conditions: no previous habituation to the experimental context (high novelty stress/arousal level or extensive prior habituation (reduced novelty stress/arousal level. Results indicated that in the habituated rats, exposure to an out-of-context stressor (i.e, elevated platform stress impaired consolidation and retrieval, but not acquisition, of the task. Non-habituated animals under both stressed and control conditions did not show retention of the task. In habituated rats, RU-486 (10 ng/side, a glucocorticoid receptor (GR antagonist, or propranolol (0.75 µg/side, a beta-adrenergic antagonist, injected into the basolateral amygdala (BLA, prevented the impairing effects of the stressor on consolidation, but not on retrieval. The CB1/CB2 receptor agonist WIN55,212-2 (WIN, 5 µg/side microinjected into the BLA did not prevent the effects of stress on either consolidation or retrieval. Taken together the results suggest that: (i GR and β-adrenergic receptors in the BLA mediate the impairing effects of stress on the consolidation, but not the retrieval, of a neutral, non-aversive hippocampal-dependent task, (ii the impairing effects of stress on hippocampal consolidation and retrieval are mediated by different neural mechanisms (i.e., different neurotransmitters or different brain areas, and (iii the effects of stress on memory depend on the interaction between several main factors such as the stage of memory processing under investigation, the animal's level of arousal and the nature of the task (neutral or aversive.

  6. Stress hormones receptors in the amygdala mediate the effects of stress on the consolidation, but not the retrieval, of a non aversive spatial task.

    Science.gov (United States)

    Segev, Amir; Ramot, Assaf; Akirav, Irit

    2012-01-01

    This study examined the effects of the arousal level of the rat and exposure to a behavioral stressor on acquisition, consolidation and retrieval of a non-aversive hippocampal-dependent learning paradigm, the object location task. Learning was tested under two arousal conditions: no previous habituation to the experimental context (high novelty stress/arousal level) or extensive prior habituation (reduced novelty stress/arousal level). Results indicated that in the habituated rats, exposure to an out-of-context stressor (i.e, elevated platform stress) impaired consolidation and retrieval, but not acquisition, of the task. Non-habituated animals under both stressed and control conditions did not show retention of the task. In habituated rats, RU-486 (10 ng/side), a glucocorticoid receptor (GR) antagonist, or propranolol (0.75 µg/side), a beta-adrenergic antagonist, injected into the basolateral amygdala (BLA), prevented the impairing effects of the stressor on consolidation, but not on retrieval. The CB1/CB2 receptor agonist WIN55,212-2 (WIN, 5 µg/side) microinjected into the BLA did not prevent the effects of stress on either consolidation or retrieval. Taken together the results suggest that: (i) GR and β-adrenergic receptors in the BLA mediate the impairing effects of stress on the consolidation, but not the retrieval, of a neutral, non-aversive hippocampal-dependent task, (ii) the impairing effects of stress on hippocampal consolidation and retrieval are mediated by different neural mechanisms (i.e., different neurotransmitters or different brain areas), and (iii) the effects of stress on memory depend on the interaction between several main factors such as the stage of memory processing under investigation, the animal's level of arousal and the nature of the task (neutral or aversive).

  7. Relationship between reaction time, fine motor control, and visual-spatial perception on vigilance and visual-motor tasks in 22q11.2 Deletion Syndrome.

    LENUS (Irish Health Repository)

    Howley, Sarah A

    2012-10-15

    22q11.2 Deletion Syndrome (22q11DS) is a common microdeletion disorder associated with mild to moderate intellectual disability and specific neurocognitive deficits, particularly in visual-motor and attentional abilities. Currently there is evidence that the visual-motor profile of 22q11DS is not entirely mediated by intellectual disability and that these individuals have specific deficits in visual-motor integration. However, the extent to which attentional deficits, such as vigilance, influence impairments on visual motor tasks in 22q11DS is unclear. This study examines visual-motor abilities and reaction time using a range of standardised tests in 35 children with 22q11DS, 26 age-matched typically developing (TD) sibling controls and 17 low-IQ community controls. Statistically significant deficits were observed in the 22q11DS group compared to both low-IQ and TD control groups on a timed fine motor control and accuracy task. The 22q11DS group performed significantly better than the low-IQ control group on an untimed drawing task and were equivalent to the TD control group on point accuracy and simple reaction time tests. Results suggest that visual motor deficits in 22q11DS are primarily attributable to deficits in psychomotor speed which becomes apparent when tasks are timed versus untimed. Moreover, the integration of visual and motor information may be intact and, indeed, represent a relative strength in 22q11DS when there are no time constraints imposed. While this may have significant implications for cognitive remediation strategies for children with 22q11DS, the relationship between reaction time, visual reasoning, cognitive complexity, fine motor speed and accuracy, and graphomotor ability on visual-motor tasks is still unclear.

  8. Temporal and spatial strategies in an active place avoidance task on Carousel: a study of effects of stability of arena rotation speed in rats

    Czech Academy of Sciences Publication Activity Database

    Bahník, Štěpán; Stuchlík, Aleš

    2015-01-01

    Roč. 3, Sep 22 (2015), e1257 ISSN 2167-8359 R&D Projects: GA MŠk(CZ) LH14053 Institutional support: RVO:67985823 Keywords : spatial navigation * interval timing * substratal idiothetic navigation * inertial idiothetic navigation * rats Subject RIV: FH - Neurology Impact factor: 2.183, year: 2015

  9. Control processes through the suppression of the automatic response activation triggered by task-irrelevant information in the Simon-type tasks.

    Science.gov (United States)

    Kim, Sanga; Lee, Sang Ho; Cho, Yang Seok

    2015-11-01

    The congruency sequence effect, one of the indices of cognitive control, refers to a smaller congruency effect after an incongruent than congruent trial. Although the effect has been found across a variety of conflict tasks, there is not yet agreement on the underlying mechanism. The present study investigated the mechanism underlying cognitive control by using a cross-task paradigm. In Experiments 1, 2, and 3, participants performed a modified Simon task and a spatial Stroop task alternately in a trial-by-trial manner. The task-irrelevant dimension of the two tasks was perceptually and conceptually identical in Experiment 1, whereas it was perceptually different but conceptually identical in Experiment 2. The response sets for both tasks were different in Experiment 3. In Experiment 4, participants performed two Simon tasks with different task-relevant dimensions. In all experiments in which the task-irrelevant dimension and response mode were shared, significant congruency sequence effects were found between the two different congruencies, indicating that Simon-type conflicts were resolved by a control mechanism, which is specific to an abstract task-irrelevant stimulus spatial dimension. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Encouraging Spatial Talk: Using Children's Museums to Bolster Spatial Reasoning

    Science.gov (United States)

    Polinsky, Naomi; Perez, Jasmin; Grehl, Mora; McCrink, Koleen

    2017-01-01

    Longitudinal spatial language intervention studies have shown that greater exposure to spatial language improves children's performance on spatial tasks. Can short naturalistic, spatial language interactions also evoke improved spatial performance? In this study, parents were asked to interact with their child at a block wall exhibit in a…

  11. How to Make Correct Predictions in False Belief Tasks without Attributing False Beliefs: An Analysis of Alternative Inferences and How to Avoid Them

    Directory of Open Access Journals (Sweden)

    Ricardo Augusto Perera

    2018-04-01

    Full Text Available The use of new paradigms of false belief tasks (FBT allowed to reduce the age of children who pass the test from the previous 4 years in the standard version to only 15 months or even a striking 6 months in the nonverbal modification. These results are often taken as evidence that infants already possess an—at least implicit—theory of mind (ToM. We criticize this inferential leap on the grounds that inferring a ToM from the predictive success on a false belief task requires to assume as premise that a belief reasoning is a necessary condition for correct action prediction. It is argued that the FBT does not satisfactorily constrain the predictive means, leaving room for the use of belief-independent inferences (that can rely on the attribution of non-representational mental states or the consideration of behavioral patterns that dispense any reference to other minds. These heuristics, when applied to the FBT, can achieve the same predictive success of a belief-based inference because information provided by the test stimulus allows the recognition of particular situations that can be subsumed by their ‘laws’. Instead of solving this issue by designing a single experimentum crucis that would render unfeasible the use of non-representational inferences, we suggest the application of a set of tests in which, although individually they can support inferences dissociated from a ToM, only an inference that makes use of false beliefs is able to correctly predict all the outcomes.

  12. Task 1 Report - Assessment of Data Availability to Inform Energy Planning Analyses: Energy Alternatives Study for the Lao People's Democratic Republic: Smart Infrastructure for the Mekong Program

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Nathan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lopez, Anthony J. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Katz, Jessica R. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Cardoso de Oliveira, Ricardo P. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Hayter, Sheila J. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-01-24

    In an effort to address concerns such as energy security, reliability, affordability, and other objectives, the Government of the Lao People's Democratic Republic (Lao PDR) is seeking to advance its expertise and experience in energy system analysis and planning to explore energy alternatives. Assessing the potential and alternatives for deploying energy technology options is often an early step - and, in most cases, an ongoing process - in planning for the development of the energy sector as a whole. Reliable and robust data are crucial to conducting these types of planning-related analyses in a transparent manner that builds confidence among power sector stakeholders and encourages investment in future energy project development and infrastructure opportunities. This report represents the first output of the Energy Alternatives Study for the Lao PDR (Energy Alternatives Study), a collaboration between Ministry of Energy and Mines and the United States Agency for International Development (USAID) under the auspices of the Smart Infrastructure for the Mekong (SIM) program. The Energy Alternatives Study includes five tasks that build upon each other to meet the goal of the project. The report summarizes the availability, quality, and accessibility of data that serve as key inputs to energy planning activities for the power sector. The purpose of this data assessment is two-fold: 1. To facilitate the informed use of existing data by highlighting applications for these data as they relate to priority energy planning analyses; and 2. To inform future investments in energy data collection and management by identifying significant data gaps and providing guidance on how to fill these gaps.

  13. Noradrenergic signaling in the medial prefrontal cortex and amygdala differentially regulates vicarious trial-and-error in a spatial decision-making task.

    Science.gov (United States)

    Amemiya, Seiichiro; Kubota, Natsuko; Umeyama, Nao; Nishijima, Takeshi; Kita, Ichiro

    2016-01-15

    In uncertain choice situations, we deliberately search and evaluate possible options before taking an action. Once we form a preference regarding the current situation, we take an action more automatically and with less deliberation. In rats, the deliberation process can be seen in vicarious trial-and-error behavior (VTE), which is a head-orienting behavior toward options at a choice point. Recent neurophysiological findings suggest that VTE reflects the rat's thinking about future options as deliberation, expectation, and planning when rats feel conflict. VTE occurs depending on the demand: an increase occurs during initial learning, and a decrease occurs with progression in learning. However, the brain circuit underlying the regulation of VTE has not been thoroughly examined. In situations in which VTE often appears, the medial prefrontal cortex (mPFC) and the amygdala (AMY) are crucial for learning and decision making. Our previous study reported that noradrenaline regulates VTE. Here, to investigate whether the mPFC and AMY are involved in regulation of VTE, we examined the effects of local injection of clonidine, an alpha2 adrenergic autoreceptor agonist, into either region in rats during VTE and choice behavior during a T-maze choice task. Injection of clonidine into either region impaired selection of the advantageous choice in the task. Furthermore, clonidine injection into the mPFC suppressed occurrence of VTE in the early phase of the task, whereas injection into the AMY inhibited the decrease in VTE in the later phase and thus maintained a high level of VTE throughout the task. These results suggest that the mPFC and AMY play a role in the increase and decrease in VTE, respectively, and that noradrenergic mechanisms mediate the dynamic regulation of VTE over experiences. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Training on motor and visual spatial learning tasks in early adulthood produces large changes in dendritic organization of prefrontal cortex and nucleus accumbens in rats given nicotine prenatally.

    Science.gov (United States)

    Muhammad, A; Mychasiuk, R; Hosain, S; Nakahashi, A; Carroll, C; Gibb, R; Kolb, B

    2013-11-12

    Experience-dependent plasticity is an ongoing process that can be observed and measured at multiple levels. The first goal of this study was to examine the effects of prenatal nicotine on the performance of rats in three behavioral tasks (elevated plus maze (EPM), Morris water task (MWT), and Whishaw tray reaching). The second goal of this experiment sought to examine changes in dendritic organization following exposure to the behavioral training paradigm and/or low doses of prenatal nicotine. Female Long-Evans rats were administered daily injections of nicotine for the duration of pregnancy and their pups underwent a regimen of behavioral training in early adulthood (EPM, MWT, and Whishaw tray reaching). All offspring exposed to nicotine prenatally exhibited substantial increases in anxiety. Male offspring also showed increased efficiency in the Whishaw tray-reaching task and performed differently than the other groups in the probe trial of the MWT. Using Golgi-Cox staining we examined the dendritic organization of the medial and orbital prefrontal cortex as well as the nucleus accumbens. Participation in the behavioral training paradigm was associated with dramatic reorganization of dendritic morphology and spine density in all brain regions examined. Although both treatments (behavior training and prenatal nicotine exposure) markedly altered dendritic organization, the effects of the behavioral experience were much larger than those of the prenatal drug exposure, and in some cases interacted with the drug effects. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

  15. Recommendations to the NRC for review criteria for alternative methods of low-level radioactive waste disposal: Task 2a, Below-ground vaults

    International Nuclear Information System (INIS)

    Denson, R.H.; Bennett, R.D.; Wamsley, R.M.; Bean, D.L.; Ainsworth, D.L.

    1987-12-01

    The US Army Engineer Waterways Experiment Station (WES) and the US Army Engineer Division, Huntsville (HNDED) have developed general design criteria and specific design review criteria for the below-ground vault (BGV) alternative method of low-level radioactive waste (LLW) disposal. A BGV is a reinforced concrete vault (floor, walls, and roof) placed underground below the frost line, and above the water table, surrounded by filter blanket and drainage zones and covered with a low permeability earth layer and top soil with vegetation. Eight major review criteria categories have been developed ranging from the loads imposed on the BGV structure through material quality and durability considerations. Specific design review criteria have been developed in detail for seven of the eight major categories. 59 refs., 14 figs., 2 tabs

  16. Recommendations to the NRC for review criteria for alternative methods of low-level radioactive waste disposal: Task 2b: Earth-mounded concrete bunkers

    International Nuclear Information System (INIS)

    Denson, R.H.; Bennett, R.D.; Wamsley, R.M.; Bean, D.L.; Ainsworth, D.L.

    1988-01-01

    The US Army Engineers Waterways Experiment Station (WES) and US Army Engineer Division, Huntsville (HNDED) have developed general design criteria and specific design review criteria for the earth-mounded concrete bunker (EMCB) alternative method of low-level radioactive waste (LLW) disposal. An EMCB is generally described as a reinforced concrete vault placed below grade, underneath a tumulus, surrounded by filter-blanket and drainage zones. The tumulus is covered over with a low permeability cover layer and top soil with vegetation. Eight major review criteria categories have been developed ranging from the loads imposed on the EMCB structure through material quality and durability considerations. Specific design review criteria have been developed in detail for each of the eight major categories. 63 refs., 13 figs., 2 tabs

  17. Effect of dopamine D1 receptor antagonist SCH23390 and D1 agonist A77636 on active allothetic place avoidance, a spatial cognition task

    Czech Academy of Sciences Publication Activity Database

    Stuchlík, Aleš; Valeš, Karel

    2006-01-01

    Roč. 172, č. 2 (2006), s. 250-255 ISSN 0166-4328 R&D Projects: GA ČR(CZ) GA309/06/1231; GA ČR(CZ) GP309/03/P126; GA MŠk(CZ) 1M0517; GA MŠk(CZ) LC554 Institutional research plan: CEZ:AV0Z50110509 Keywords : spatial memory * cognition * dopamine Subject RIV: FH - Neurology Impact factor: 2.591, year: 2006

  18. Histamine ameliorates spatial memory deficits induced by MK-801 infusion into ventral hippocampus as evaluated by radial maze task in rats

    Institute of Scientific and Technical Information of China (English)

    Li-sha XU; Li-xia YANG; Wei-wei HU; Xiao YU; Li MA; Lu-ying LIU; Er-qing WEI; Zhong CHEN

    2005-01-01

    Aim: To investigate the role of histamine in memory deficits induced by MK-801 infusion into the ventral hippocampus in rats. Methods: An 8-arm radial maze (4arms baited) was used to assess spatial memory. Results: Bilateral ventral intrahippocampal (ih) infusion of MK-801 (0.3 μg/site), an N-methyl-D-aspartate (NMDA) antagonist, impaired the retrieval process in both working memory and reference memory. Intrahippocampal injection of histamine (25 or 50 ng/site) or intraperitoneal (ip) injection of histidine (25, 50 or 100 mg/kg) markedly ameliorated the spatial memory deficits induced by MK-801. Both the histamine H1 antagonist pyrilamine (0.5 or 1.0 μg/site, ih) and the H2 antagonist cimetidine (2.5 μg/site,ih) abolished the ameliorating effect of histidine (100 mg/kg, ip) on reference memory deficits, but not that on working memory deficits induced by MK-801. Conclusion:The results indicate that histamine in the ventral hippocampus can ameliorate MK-801-induced spatial memory deficits, and that histamine's effect on reference memory is mediated by postsynaptic histamine H1 and H2 receptors.

  19. Tiny tweaks, big changes: An alternative strategy to empower ethical culture of human research in anesthesia (A Taiwan Acta Anesthesiologica Taiwanica-Ethics Review Task Force Report).

    Science.gov (United States)

    Luk, Hsiang-Ning; Ennever, John F; Day, Yuan-Ji; Wong, Chih-Shung; Sun, Wei-Zen

    2015-03-01

    For this guidance article, the Ethics Review Task Force (ERTF) of the Journal reviewed and discussed the ethics issues related to publication of human research in the field of anesthesia. ERTF first introduced international ethics principles and minimal requirements of reporting of ethics practices, followed by discussing the universal problems of publication ethics. ERTF then compared the accountability and methodology of several medical journals in assuring authors' ethics compliance. Using the Taiwan Institutional Review Board system as an example, ERTF expressed the importance of institutional review board registration and accreditation to assure human participant protection. ERTF presented four major human research misconducts in the field of anesthesia in recent years. ERTF finally proposed a flow-chart to guide journal peer reviewers and editors in ethics review during the editorial process in publishing. Examples of template languages applied in the Ethics statement section in the manuscript are expected to strengthen the ethics compliance of the authors and to set an ethical culture for all the stakeholders involved in human research. Copyright © 2015. Published by Elsevier B.V.

  20. MGlu5 antagonism impairs exploration and memory of spatial and non-spatial stimuli in rats

    DEFF Research Database (Denmark)

    Christoffersen, Gert Rene Juul; Simonyi, Agnes; Schachtman, Todd R.

    2008-01-01

    and it was found that: 1) Locomotion during exploration of spatial environments and exploration time at novel objects were reduced by i.p. but not by prelimbic administration of MPEP, 2) spatial short-term memory was impaired in cross-maze and object discrimination was reduced after both types of administration, 3......) long-term retention of spatial conditioning in the cross-maze was inhibited after i.p. applications which 4) also inhibited spontaneous alternation performance during maze-exploration. Reduced exploratory locomotion and exploration time after i.p. injections may have contributed to the observed......Metabotropic glutamate receptor subtype 5 (mGlu5) has been implicated in memory processing in some but not all learning tasks.  The reason why this receptor is involved in some tasks but not in others remains to be determined.  The present experiments using rats examined effects of the mGlu5...

  1. Evaluation of alternative shaft-sinking techniques for high-level nuclear waste (HLW) deep geologic repositories. Final report (Task 3), June 1981-July 1982

    International Nuclear Information System (INIS)

    Gonano, L.; Findley, D.; Wildanger, W.; Gates, R.; Phillips, S.

    1983-03-01

    This report represents the results of Task 3 of US Nuclear Regulatory Commission (NRC) Contract, Technical Assistance for Repository Design. The purpose of the complete project is to provide NRC with technical assistance for the following reasons: To enable the focused, adequate review by NRC of aspects related to design and construction of an in situ test facility and final geologic repository, as presented in US Department of Energy (DOE) Site Characterization Reports (SRC), To ascertain that the DOE site characterization program will provide, as far as possible, all the information necessary to permit a review to be conducted by NRC of a license application for construction authorization. It is assumed that the Site Characterization Report and License Application will describe the exploratory shaft and concept designs for the repository shafts. This report provides a comparative evaluation of various shaft sinking techniques for production shafts for a repository. The primary comparative evaluation has been conducted for 14-ft internal diameter shafts developed in two composite media using four different methods of sinking/lining. The technical, cost and schedule comparisons draw a major distinction between shafts sunk blind and those which utilize bottom access. Based on the system of ranking introduced to grade the significant attributes of each method and the resulting design, it is concluded that for application to repository access, no one particular method of sinking exhibits a clear overall superiority. When a specific site is made available for a study of the most suitable shaft sinking methods, it will be necessary to establish actual geological conditions and technological capabilities and the comparisons presented herein reviewed accordingly

  2. Visual Saliency Prediction and Evaluation across Different Perceptual Tasks.

    Directory of Open Access Journals (Sweden)

    Shafin Rahman

    Full Text Available Saliency maps produced by different algorithms are often evaluated by comparing output to fixated image locations appearing in human eye tracking data. There are challenges in evaluation based on fixation data due to bias in the data. Properties of eye movement patterns that are independent of image content may limit the validity of evaluation results, including spatial bias in fixation data. To address this problem, we present modeling and evaluation results for data derived from different perceptual tasks related to the concept of saliency. We also present a novel approach to benchmarking to deal with some of the challenges posed by spatial bias. The results presented establish the value of alternatives to fixation data to drive improvement and development of models. We also demonstrate an approach to approximate the output of alternative perceptual tasks based on computational saliency and/or eye gaze data. As a whole, this work presents novel benchmarking results and methods, establishes a new performance baseline for perceptual tasks that provide an alternative window into visual saliency, and demonstrates the capacity for saliency to serve in approximating human behaviour for one visual task given data from another.

  3. Singing numbers…in cognitive space--a dual-task study of the link between pitch, space, and numbers.

    Science.gov (United States)

    Fischer, Martin H; Riello, Marianna; Giordano, Bruno L; Rusconi, Elena

    2013-04-01

    We assessed the automaticity of spatial-numerical and spatial-musical associations by testing their intentionality and load sensitivity in a dual-task paradigm. In separate sessions, 16 healthy adults performed magnitude and pitch comparisons on sung numbers with variable pitch. Stimuli and response alternatives were identical, but the relevant stimulus attribute (pitch or number) differed between tasks. Concomitant tasks required retention of either color or location information. Results show that spatial associations of both magnitude and pitch are load sensitive and that the spatial association for pitch is more powerful than that for magnitude. These findings argue against the automaticity of spatial mappings in either stimulus dimension. Copyright © 2013 Cognitive Science Society, Inc.

  4. Differentiating Spatial Memory from Spatial Transformations

    Science.gov (United States)

    Street, Whitney N.; Wang, Ranxiao Frances

    2014-01-01

    The perspective-taking task is one of the most common paradigms used to study the nature of spatial memory, and better performance for certain orientations is generally interpreted as evidence of spatial representations using these reference directions. However, performance advantages can also result from the relative ease in certain…

  5. A Mathematical Model of Levodopa Medication Effect on Basal Ganglia in Parkinson's Disease: An Application to the Alternate Finger Tapping Task.

    Science.gov (United States)

    Baston, Chiara; Contin, Manuela; Calandra Buonaura, Giovanna; Cortelli, Pietro; Ursino, Mauro

    2016-01-01

    Malfunctions in the neural circuitry of the basal ganglia (BG), induced by alterations in the dopaminergic system, are responsible for an array of motor disorders and milder cognitive issues in Parkinson's disease (PD). Recently Baston and Ursino (2015a) presented a new neuroscience mathematical model aimed at exploring the role of basal ganglia in action selection. The model is biologically inspired and reproduces the main BG structures and pathways, modeling explicitly both the dopaminergic and the cholinergic system. The present work aims at interfacing this neurocomputational model with a compartmental model of levodopa, to propose a general model of medicated Parkinson's disease. Levodopa effect on the striatum was simulated with a two-compartment model of pharmacokinetics in plasma joined with a motor effect compartment. The latter is characterized by the levodopa removal rate and by a sigmoidal relationship (Hill law) between concentration and effect. The main parameters of this relationship are saturation, steepness, and the half-maximum concentration. The effect of levodopa is then summed to a term representing the endogenous dopamine effect, and is used as an external input for the neurocomputation model; this allows both the temporal aspects of medication and the individual patient characteristics to be simulated. The frequency of alternate tapping is then used as the outcome of the whole model, to simulate effective clinical scores. Pharmacokinetic-pharmacodynamic modeling was preliminary performed on data of six patients with Parkinson's disease (both "stable" and "wearing-off" responders) after levodopa standardized oral dosing over 4 h. Results show that the model is able to reproduce the temporal profiles of levodopa in plasma and the finger tapping frequency in all patients, discriminating between different patterns of levodopa motor response. The more influential parameters are the Hill coefficient, related with the slope of the effect sigmoidal

  6. Inhibition of connexin43 hemichannels impairs spatial short-term memory without affecting spatial working memory

    Directory of Open Access Journals (Sweden)

    Laura Walrave

    2016-12-01

    Full Text Available Astrocytes are active players in higher brain function as they can release gliotransmitters, which are essential for synaptic plasticity. Various mechanisms have been proposed for gliotransmission, including vesicular mechanisms as well as non-vesicular ones, for example by passive diffusion via connexin hemichannels (HCs. We here investigated whether interfering with connexin43 (Cx43 HCs influenced hippocampal spatial memory. We made use of the peptide Gap19 that blocks HCs but not gap junction channels and is specific for Cx43. To this end, we microinfused transactivator of transcription linked Gap19 (TAT-Gap19 into the brain ventricle of male NMRI mice and assessed spatial memory in a Y maze. We found that the in vivo blockade of Cx43 HCs did not affect the locomotor activity or spatial working memory in a spontaneous alternation Y maze task. Cx43 blockade did however significantly impair the spatial short-term memory in a delayed spontaneous alternation Y maze task. These results indicate that Cx43 HCs play a role in spatial short-term memory.

  7. Postoperative pain impairs subsequent performance on a spatial memory task via effects on N-methyl-D-aspartate receptor in aged rats.

    Science.gov (United States)

    Chi, Haidong; Kawano, Takashi; Tamura, Takahiko; Iwata, Hideki; Takahashi, Yasuhiro; Eguchi, Satoru; Yamazaki, Fumimoto; Kumagai, Naoko; Yokoyama, Masataka

    2013-12-18

    Pain may be associated with postoperative cognitive dysfunction (POCD); however, this relationship remains under investigated. Therefore, we examined the impact of postoperative pain on cognitive functions in aged animals. Rats were allocated to the following groups: control (C), 1.2 % isoflurane for 2 hours alone (I), I with laparotomy (IL), IL with analgesia using local ropivacaine (IL+R), and IL with analgesia using systemic morphine (IL+M). Pain was assessed by rat grimace scale (RGS). Spatial memory was evaluated using a radial maze from postoperative days (POD) 3 to 14. NMDA receptor (NR) 2 subunits in hippocampus were measured by ELISA. Finally, effects of memantine, a low-affinity uncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist, on postoperative cognitive performance were tested. Postoperative RGS was increased in Group IL, but not in other groups. The number of memory errors in Group I were comparable to that in Group C, whereas errors in Group IL were increased. Importantly, in Group IL+R and IL+M, cognitive impairment was not found. The memory errors were positively correlated with the levels of NMDA receptor 2 subunits in hippocampus. Prophylactic treatment with memantine could prevent the development of memory deficits observed in Group IL without an analgesic effect. Postoperative pain contributes to the development of memory deficits after anesthesia and surgery via up-regulation of hippocampal NMDA receptors. Our findings suggest that postoperative pain management may be important for the prevention of POCD in elderly patients. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. The performance of cleaner wrasse, Labroides dimidiatus, in a reversal learning task varies across experimental paradigms

    Directory of Open Access Journals (Sweden)

    Simon Gingins

    2018-05-01

    Full Text Available Testing performance in controlled laboratory experiments is a powerful tool for understanding the extent and evolution of cognitive abilities in non-human animals. However, cognitive testing is prone to a number of potential biases, which, if unnoticed or unaccounted for, may affect the conclusions drawn. We examined whether slight modifications to the experimental procedure and apparatus used in a spatial task and reversal learning task affected performance outcomes in the bluestreak cleaner wrasse, Labroides dimidiatus (hereafter “cleaners”. Using two-alternative forced-choice tests, fish had to learn to associate a food reward with a side (left or right in their holding aquarium. Individuals were tested in one of four experimental treatments that differed slightly in procedure and/or physical set-up. Cleaners from all four treatment groups were equally able to solve the initial spatial task. However, groups differed in their ability to solve the reversal learning task: no individuals solved the reversal task when tested in small tanks with a transparent partition separating the two options, whereas over 50% of individuals solved the task when performed in a larger tank, or with an opaque partition. These results clearly show that seemingly insignificant details to the experimental set-up matter when testing performance in a spatial task and might significantly influence the outcome of experiments. These results echo previous calls for researchers to exercise caution when designing methodologies for cognition tasks to avoid misinterpretations.

  9. The performance of cleaner wrasse, Labroides dimidiatus, in a reversal learning task varies across experimental paradigms.

    Science.gov (United States)

    Gingins, Simon; Marcadier, Fanny; Wismer, Sharon; Krattinger, Océane; Quattrini, Fausto; Bshary, Redouan; Binning, Sandra A

    2018-01-01

    Testing performance in controlled laboratory experiments is a powerful tool for understanding the extent and evolution of cognitive abilities in non-human animals. However, cognitive testing is prone to a number of potential biases, which, if unnoticed or unaccounted for, may affect the conclusions drawn. We examined whether slight modifications to the experimental procedure and apparatus used in a spatial task and reversal learning task affected performance outcomes in the bluestreak cleaner wrasse, Labroides dimidiatus (hereafter "cleaners"). Using two-alternative forced-choice tests, fish had to learn to associate a food reward with a side (left or right) in their holding aquarium. Individuals were tested in one of four experimental treatments that differed slightly in procedure and/or physical set-up. Cleaners from all four treatment groups were equally able to solve the initial spatial task. However, groups differed in their ability to solve the reversal learning task: no individuals solved the reversal task when tested in small tanks with a transparent partition separating the two options, whereas over 50% of individuals solved the task when performed in a larger tank, or with an opaque partition. These results clearly show that seemingly insignificant details to the experimental set-up matter when testing performance in a spatial task and might significantly influence the outcome of experiments. These results echo previous calls for researchers to exercise caution when designing methodologies for cognition tasks to avoid misinterpretations.

  10. Dissociable effects of 5-HT2C receptor antagonism and genetic inactivation on perseverance and learned non-reward in an egocentric spatial reversal task.

    Directory of Open Access Journals (Sweden)

    Simon R O Nilsson

    Full Text Available Cognitive flexibility can be assessed in reversal learning tests, which are sensitive to modulation of 5-HT2C receptor (5-HT2CR function. Successful performance in these tests depends on at least two dissociable cognitive mechanisms which may separately dissipate associations of previous positive and negative valence. The first is opposed by perseverance and the second by learned non-reward. The current experiments explored the effect of reducing function of the 5-HT2CR on the cognitive mechanisms underlying egocentric reversal learning in the mouse. Experiment 1 used the 5-HT2CR antagonist SB242084 (0.5 mg/kg in a between-groups serial design and Experiment 2 used 5-HT2CR KO mice in a repeated measures design. Animals initially learned to discriminate between two egocentric turning directions, only one of which was food rewarded (denoted CS+, CS-, in a T- or Y-maze configuration. This was followed by three conditions; (1 Full reversal, where contingencies reversed; (2 Perseverance, where the previous CS+ became CS- and the previous CS- was replaced by a novel CS+; (3 Learned non-reward, where the previous CS- became CS+ and the previous CS+ was replaced by a novel CS-. SB242084 reduced perseverance, observed as a decrease in trials and incorrect responses to criterion, but increased learned non-reward, observed as an increase in trials to criterion. In contrast, 5-HT2CR KO mice showed increased perseverance. 5-HT2CR KO mice also showed retarded egocentric discrimination learning. Neither manipulation of 5-HT2CR function affected performance in the full reversal test. These results are unlikely to be accounted for by increased novelty attraction, as SB242084 failed to affect performance in an unrewarded novelty task. In conclusion, acute 5-HT2CR antagonism and constitutive loss of the 5-HT2CR have opposing effects on perseverance in egocentric reversal learning in mice. It is likely that this difference reflects the broader impact of 5HT2CR loss

  11. A Barnes Maze for Juvenile Rats Delineates the Emergence of Spatial Navigation Ability

    Science.gov (United States)

    McHail, Daniel G.; Valibeigi, Nazanin; Dumas, Theodore C.

    2018-01-01

    The neural bases of cognition may be greatly informed by relating temporally defined developmental changes in behavior with concurrent alterations in neural function. A robust improvement in performance in spatial learning and memory tasks occurs at 3 wk of age in rodents. We reported that the developmental increase of spontaneous alternation in a…

  12. Brain activations during bimodal dual tasks depend on the nature and combination of component tasks

    Directory of Open Access Journals (Sweden)

    Emma eSalo

    2015-02-01

    Full Text Available We used functional magnetic resonance imaging to investigate brain activations during nine different dual tasks in which the participants were required to simultaneously attend to concurrent streams of spoken syllables and written letters. They performed a phonological, spatial or simple (speaker-gender or font-shade discrimination task within each modality. We expected to find activations associated specifically with dual tasking especially in the frontal and parietal cortices. However, no brain areas showed systematic dual task enhancements common for all dual tasks. Further analysis revealed that dual tasks including component tasks that were according to Baddeley’s model modality atypical, that is, the auditory spatial task or the visual phonological task, were not associated with enhanced frontal activity. In contrast, for other dual tasks, activity specifically associated with dual tasking was found in the left or bilateral frontal cortices. Enhanced activation in parietal areas, however, appeared not to be specifically associated with dual tasking per se, but rather with intermodal attention switching. We also expected effects of dual tasking in left frontal supramodal phonological processing areas when both component tasks required phonological processing and in right parietal supramodal spatial processing areas when both tasks required spatial processing. However, no such effects were found during these dual tasks compared with their component tasks performed separately. Taken together, the current results indicate that activations during dual tasks depend in a complex manner on specific demands of component tasks.

  13. Piped water consumption in Ghana: A case study of temporal and spatial patterns of clean water demand relative to alternative water sources in rural small towns

    OpenAIRE

    Kulinkina, Alexandra V.; Kosinski, Karen C.; Liss, Alexander; Adjei, Michael N.; Ayamgah, Gilbert A.; Webb, Patrick; Gute, David M.; Plummer, Jeanine D.; Naumova, Elena N.

    2016-01-01

    Continuous access to adequate quantities of safe water is essential for human health and socioeconomic development. Piped water systems (PWSs) are an increasingly common type of water supply in rural African small towns. Despite providing the highest and most flexible level of service with better microbiological water quality to their users, these systems remain vulnerable to rural water sustainability challenges. We assessed temporal and spatial patterns in water consumption from public stan...

  14. The blind men meet the elephant at the dam: Alternative spatial and taxonomic components reveal different insights about how low-head dams impact fish biodiversity

    Science.gov (United States)

    Fencl, Jane S.; Mather, Martha E.; Smith, Joseph M.; Hitchman, Sean M.

    2017-01-01

    Dams are ubiquitous environmental impacts that threaten aquatic ecosystems. The ability to compare across research studies is essential to conserve the native biodiversity that is impacted by the millions of low‐head dams that currently fragment streams and rivers. Here, we identify a previously unaddressed obstacle that impedes this generalization. Specifically, divergent spatial and taxonomic approaches that result from different conceptualizations of the dam‐biodiversity problem can produce conflicting science‐based conclusions about the same dam impact. In this research, using the same dammed and undammed sites, we evaluated the scientific generality of different conceptualizations of the dam‐biodiversity problem. We compared two different but commonly used spatial approaches—(1) above dam–below dam vs. (2) undammed–dammed comparisons—and 11 different, commonly used taxonomic approaches (three assemblage summaries, eight guilds). Sites above the dam structure had less diverse fish assemblages than sites below dams, whereas sites below the dam structure were similar to undammed sites. Thus, spatial approach 1 detected a large dam effect and spatial approach 2 detected a small dam effect. Similarly, some taxonomic responses (species richness, diversity, abundance, and number of guilds) detected large dam effects; other responses detected small (riffle specialist guild) or no dam effects (pool generalists). In summary, our results showed that how the problem was framed altered scientific conclusions and created different dam realities. The metaphor of how individual blind men disagree about the structure of an elephant, based on examinations of different body parts, reinforces the need for a coordinated, holistic perspective on dam research. Although no single approach is adequate for all problems, identifying the form, consequences of, and relationships among different research conceptualizations will set the stage for future syntheses of dam

  15. Performance Enhancements Under Dual-task Conditions

    Science.gov (United States)

    Kramer, A. F.; Wickens, C. D.; Donchin, E.

    1984-01-01

    Research on dual-task performance has been concerned with delineating the antecedent conditions which lead to dual-task decrements. Capacity models of attention, which propose that a hypothetical resource structure underlies performance, have been employed as predictive devices. These models predict that tasks which require different processing resources can be more successfully time shared than tasks which require common resources. The conditions under which such dual-task integrality can be fostered were assessed in a study in which three factors likely to influence the integrality between tasks were manipulated: inter-task redundancy, the physical proximity of tasks and the task relevant objects. Twelve subjects participated in three experimental sessions in which they performed both single and dual-tasks. The primary task was a pursuit step tracking task. The secondary tasks required the discrimination between different intensities or different spatial positions of a stimulus. The results are discussed in terms of a model of dual-task integrality.

  16. Modality-specific effects on crosstalk in task switching: evidence from modality compatibility using bimodal stimulation.

    Science.gov (United States)

    Stephan, Denise Nadine; Koch, Iring

    2016-11-01

    The present study was aimed at examining modality-specific influences in task switching. To this end, participants switched either between modality compatible tasks (auditory-vocal and visual-manual) or incompatible spatial discrimination tasks (auditory-manual and visual-vocal). In addition, auditory and visual stimuli were presented simultaneously (i.e., bimodally) in each trial, so that selective attention was required to process the task-relevant stimulus. The inclusion of bimodal stimuli enabled us to assess congruence effects as a converging measure of increased between-task interference. The tasks followed a pre-instructed sequence of double alternations (AABB), so that no explicit task cues were required. The results show that switching between two modality incompatible tasks increases both switch costs and congruence effects compared to switching between two modality compatible tasks. The finding of increased congruence effects in modality incompatible tasks supports our explanation in terms of ideomotor "backward" linkages between anticipated response effects and the stimuli that called for this response in the first place. According to this generalized ideomotor idea, the modality match between response effects and stimuli would prime selection of a response in the compatible modality. This priming would cause increased difficulties to ignore the competing stimulus and hence increases the congruence effect. Moreover, performance would be hindered when switching between modality incompatible tasks and facilitated when switching between modality compatible tasks.

  17. Alternative security

    International Nuclear Information System (INIS)

    Weston, B.H.

    1990-01-01

    This book contains the following chapters: The Military and Alternative Security: New Missions for Stable Conventional Security; Technology and Alternative Security: A Cherished Myth Expires; Law and Alternative Security: Toward a Just World Peace; Politics and Alternative Security: Toward a More Democratic, Therefore More Peaceful, World; Economics and Alternative Security: Toward a Peacekeeping International Economy; Psychology and Alternative Security: Needs, Perceptions, and Misperceptions; Religion and Alternative Security: A Prophetic Vision; and Toward Post-Nuclear Global Security: An Overview

  18. Reinforced spatial alternation as an animal model of obsessive-compulsive disorder (OCD): investigation of 5-HT2C and 5-HT1D receptor involvement in OCD pathophysiology.

    Science.gov (United States)

    Tsaltas, Eleftheria; Kontis, Dimitris; Chrysikakou, Sofia; Giannou, Haralambos; Biba, Angeliki; Pallidi, Stella; Christodoulou, Angeliki; Maillis, Antonis; Rabavilas, Andreas

    2005-05-15

    This study introduces a laboratory model of compulsive behavior based on persistence in the context of rewarded spatial alternation. Rats were screened for spontaneous persistence during T-maze reinforced alternation. Experiment 1: One high and one low spontaneous persistence group (n = 8) received 20 injections of fluoxetine, a matched pair saline, both followed by 4 days of meta-chlorophenylpiperazine (mCPP) challenge. Experiment 2: Five matched groups of rats (n = 9) received pretreatment (20 injections) with fluoxetine, mCPP, desipramine, diazepam or saline, followed by 4 days of mCPP challenge (fluoxetine in mCPP group). After washout, animals received 2 days of naratriptan, followed by another 2-day mCPP challenge. In both experiments mCPP significantly increased persistence in saline controls. Fluoxetine also acutely increased persistence scores: after a gradual return to baseline, these scores showed tolerance to mCPP. Experiment 1: This pattern was significant in high but not low initial persistence groups. Experiment 2: Fluoxetine and mCPP showed cross-tolerance. Neither desipramine nor diazepam protected against mCPP challenge. Persistence scores returned to baseline during washout and naratriptan and were thereafter increased by another mCPP challenge in all but the fluoxetine and mCPP groups, suggesting 5-HT2C receptor mediation. This model is based on spontaneous persistence behavior showing pharmacological responses concordant with those of compulsive symptomatology.

  19. Task-related modulation of visual neglect in cancellation tasks

    OpenAIRE

    Sarri, Margarita; Greenwood, Richard; Kalra, Lalit; Driver, Jon

    2008-01-01

    Unilateral neglect involves deficits of spatial exploration and awareness that do not always affect a fixed portion of extrapersonal space, but may vary with current stimulation and possibly with task demands. Here, we assessed any ‘top-down’, task-related influences on visual neglect, with novel experimental variants of the cancellation test. Many different versions of the cancellation test are used clinically, and can differ in the extent of neglect revealed, though the exact factors determ...

  20. Alternative additives; Alternative additiver

    Energy Technology Data Exchange (ETDEWEB)

    2007-08-15

    In this project a number of industrial and agricultural waste products have been characterised and evaluated in terms of alkali-getter performance. The intended use is for biomass-fired power stations aiming at reducing corrosion or slagging related problems. The following products have been obtained, characterised and evaluated: 1) Brewery draff 2) Danish de-gassed manure 3) Paper sludge 4) Moulding sand 5) Spent bleaching earth 6) Anorthosite 7) Sand 8) Clay-sludge. Most of the above alternative additive candidates are deemed unsuitable due to insufficient chemical effect and/or expensive requirements for pre-treatment (such as drying and transportation). 3 products were selected for full-scale testing: de-gassed manure, spent bleaching earth and clay slugde. The full scale tests were undertaken at the biomass-fired power stations in Koege, Slagelse and Ensted. Spent bleaching earth (SBE) and clay sludge were the only tested additive candidates that had a proven ability to react with KCl, to thereby reduce Cl-concentrations in deposits, and reduce the deposit flux to superheater tubes. Their performance was shown to nearly as good as commercial additives. De-gassed manure, however, did not evaluate positively due to inhibiting effects of Ca in the manure. Furthermore, de-gassed manure has a high concentration of heavy metals, which imposes a financial burden with regard to proper disposal of the ash by-products. Clay-sludge is a wet clay slurring, and drying and transportation of this product entails substantial costs. Spent bleaching does not require much pre-treatment and is therefore the most promising alternative additive. On the other hand, bleaching earth contains residual plant oil which means that a range of legislation relating to waste combustion comes into play. Not least a waste combustion fee of 330 DKK/tonne. For all alternative (and commercial) additives disposal costs of the increase ash by-products represents a significant cost. This is

  1. Spatial and spectral resolution of carbonaceous material from hematite (α-Fe2O3) using multivariate curve resolution-alternating least squares (MCR-ALS) with Raman microspectroscopic mapping: implications for the search for life on Mars.

    Science.gov (United States)

    Smith, Joseph P; Smith, Frank C; Booksh, Karl S

    2017-08-21

    The search for evidence of extant or past life on Mars is a primary objective of both the upcoming Mars 2020 rover (NASA) and ExoMars 2020 rover (ESA/Roscosmos) missions. This search will involve the detection and identification of organic molecules and/or carbonaceous material within the Martian surface environment. For the first time on a mission to Mars, the scientific payload for each rover will include a Raman spectrometer, an instrument well-suited for this search. Hematite (α-Fe 2 O 3 ) is a widespread mineral on the Martian surface. The 2LO Raman band of hematite and the Raman D-band of carbonaceous material show spectral overlap, leading to the potential misidentification of hematite as carbonaceous material. Here we report the ability to spatially and spectrally differentiate carbonaceous material from hematite using multivariate curve resolution-alternating least squares (MCR-ALS) applied to Raman microspectroscopic mapping under both 532 nm and 785 nm excitation. For this study, a sample comprised of hematite, carbonaceous material, and substrate-adhesive epoxy in spatially distinct domains was constructed. Principal component analysis (PCA) reveals that both 532 nm and 785 nm excitation produce representative three-phase systems of hematite, carbonaceous material, and substrate-adhesive epoxy in the analyzed sample. MCR-ALS with Raman microspectroscopic mapping using both 532 nm and 785 nm excitation was able to resolve hematite, carbonaceous material, and substrate-adhesive epoxy by generating spatially-resolved chemical maps and corresponding Raman spectra of these spatially distinct chemical species. Moreover, MCR-ALS applied to the combinatorial data sets of 532 nm and 785 nm excitation, which contain hematite and carbonaceous material within the same locations, was able to resolve hematite, carbonaceous material, and substrate-adhesive epoxy. Using multivariate analysis with Raman microspectroscopic mapping, 785 nm excitation more effectively

  2. Alternative Work Schedules: Definitions

    Science.gov (United States)

    Journal of the College and University Personnel Association, 1977

    1977-01-01

    The term "alternative work schedules" encompasses any variation of the requirement that all permanent employees in an organization or one shift of employees adhere to the same five-day, seven-to-eight-hour schedule. This article defines staggered hours, flexible working hours (flexitour and gliding time), compressed work week, the task system, and…

  3. Parietal theta burst TMS: Functional fractionation observed during bistable perception not evident in attention tasks.

    Science.gov (United States)

    Schauer, Georg; Kanai, Ryota; Brascamp, Jan W

    2016-02-01

    When visual input is ambiguous, perception spontaneously alternates between interpretations: bistable perception. Studies have identified two distinct sites near the right intraparietal sulcus where inhibitory transcranial magnetic stimulation (TMS) affects the frequency of occurrence of these alternations, but strikingly with opposite directions of effect for the two sites. Lesion and TMS studies on spatial and sustained attention have also indicated a parcellation of right parietal cortex, into areas serving distinct attentional functions. We used the exact TMS procedure previously employed to affect bistable perception, yet measured its effect on spatial and sustained attention tasks. Although there was a trend for TMS to affect performance, trends were consistently similar for both parietal sites, with no indication of opposite effects. We interpret this as signifying that the previously observed parietal fractionation of function regarding the perception of ambiguous stimuli is not due to TMS-induced modification of spatial or sustained attention. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Historical Evolution of Spatial Abilities

    Directory of Open Access Journals (Sweden)

    A. Ardila

    1993-01-01

    Full Text Available Historical evolution and cross-cultural differences in spatial abilities are analyzed. Spatial abilities have been found to be significantly associated with the complexity of geographical conditions and survival demands. Although impaired spatial cognition is found in cases of, exclusively or predominantly, right hemisphere pathology, it is proposed that this asymmetry may depend on the degree of training in spatial abilities. It is further proposed that spatial cognition might have evolved in a parallel way with cultural evolution and environmental demands. Contemporary city humans might be using spatial abilities in some new, conceptual tasks that did not exist in prehistoric times: mathematics, reading, writing, mechanics, music, etc. Cross-cultural analysis of spatial abilities in different human groups, normalization of neuropsychological testing instruments, and clinical observations of spatial ability disturbances in people with different cultural backgrounds and various spatial requirements, are required to construct a neuropsychological theory of brain organization of spatial cognition.

  5. Analysis of Spatial Concepts, Spatial Skills and Spatial Representations in New York State Regents Earth Science Examinations

    Science.gov (United States)

    Kastens, Kim A.; Pistolesi, Linda; Passow, Michael J.

    2014-01-01

    Research has shown that spatial thinking is important in science in general, and in Earth Science in particular, and that performance on spatially demanding tasks can be fostered through instruction. Because spatial thinking is rarely taught explicitly in the U.S. education system, improving spatial thinking may be "low-hanging fruit" as…

  6. Sequential Modulations in a Combined Horizontal and Vertical Simon Task: Is There ERP Evidence for Feature Integration Effects?

    Science.gov (United States)

    Hoppe, Katharina; Küper, Kristina; Wascher, Edmund

    2017-01-01

    In the Simon task, participants respond faster when the task-irrelevant stimulus position and the response position are corresponding, for example on the same side, compared to when they have a non-corresponding relation. Interestingly, this Simon effect is reduced after non-corresponding trials. Such sequential effects can be explained in terms of a more focused processing of the relevant stimulus dimension due to increased cognitive control, which transfers from the previous non-corresponding trial (conflict adaptation effects). Alternatively, sequential modulations of the Simon effect can also be due to the degree of trial-to-trial repetitions and alternations of task features, which is confounded with the correspondence sequence (feature integration effects). In the present study, we used a spatially two-dimensional Simon task with vertical response keys to examine the contribution of adaptive cognitive control and feature integration processes to the sequential modulation of the Simon effect. The two-dimensional Simon task creates correspondences in the vertical as well as in the horizontal dimension. A trial-by-trial alternation of the spatial dimension, for example from a vertical to a horizontal stimulus presentation, generates a subset containing no complete repetitions of task features, but only complete alternations and partial repetitions, which are equally distributed over all correspondence sequences. In line with the assumed feature integration effects, we found sequential modulations of the Simon effect only when the spatial dimension repeated. At least for the horizontal dimension, this pattern was confirmed by the parietal P3b, an event-related potential that is assumed to reflect stimulus-response link processes. Contrary to conflict adaptation effects, cognitive control, measured by the fronto-central N2 component of the EEG, was not sequentially modulated. Overall, our data provide behavioral as well as electrophysiological evidence for feature

  7. Feature singletons attract spatial attention independently of feature priming.

    Science.gov (United States)

    Yashar, Amit; White, Alex L; Fang, Wanghaoming; Carrasco, Marisa

    2017-08-01

    People perform better in visual search when the target feature repeats across trials (intertrial feature priming [IFP]). Here, we investigated whether repetition of a feature singleton's color modulates stimulus-driven shifts of spatial attention by presenting a probe stimulus immediately after each singleton display. The task alternated every two trials between a probe discrimination task and a singleton search task. We measured both stimulus-driven spatial attention (via the distance between the probe and singleton) and IFP (via repetition of the singleton's color). Color repetition facilitated search performance (IFP effect) when the set size was small. When the probe appeared at the singleton's location, performance was better than at the opposite location (stimulus-driven attention effect). The magnitude of this attention effect increased with the singleton's set size (which increases its saliency) but did not depend on whether the singleton's color repeated across trials, even when the previous singleton had been attended as a search target. Thus, our findings show that repetition of a salient singleton's color affects performance when the singleton is task relevant and voluntarily attended (as in search trials). However, color repetition does not affect performance when the singleton becomes irrelevant to the current task, even though the singleton does capture attention (as in probe trials). Therefore, color repetition per se does not make a singleton more salient for stimulus-driven attention. Rather, we suggest that IFP requires voluntary selection of color singletons in each consecutive trial.

  8. The Importance of Gesture in Children's Spatial Reasoning

    Science.gov (United States)

    Ehrlich, Stacy B.; Levine, Susan C.; Goldin-Meadow, Susan

    2006-01-01

    On average, men outperform women on mental rotation tasks. Even boys as young as 4 1/2 perform better than girls on simplified spatial transformation tasks. The goal of our study was to explore ways of improving 5-year-olds' performance on a spatial transformation task and to examine the strategies children use to solve this task. We found that…

  9. Alternative Remedies

    Science.gov (United States)

    ... Home › Aging & Health A to Z › Alternative Remedies Font ... medical treatment prescribed by their healthcare provider. Using this type of alternative therapy along with traditional treatments is ...

  10. Alternative Fuels

    Science.gov (United States)

    Alternative fuels include gaseous fuels such as hydrogen, natural gas, and propane; alcohols such as ethanol, methanol, and butanol; vegetable and waste-derived oils; and electricity. Overview of alternative fuels is here.

  11. Alternating Hemiplegia

    Science.gov (United States)

    ... to the symptoms of the disorder. View Full Definition Treatment Drug therapy including verapamil may help to reduce the ... the more serious form of alternating hemiplegia × ... Definition Alternating hemiplegia is a rare neurological disorder that ...

  12. Regulatory Assistance, Stakeholder Outreach, and Coastal and Marine Spatial Planning Activities In Support Marine and Hydrokinetic Energy Deployment: Task 2.1.7 Permitting and Planning Fiscal Year 2012 Year-End Report

    Energy Technology Data Exchange (ETDEWEB)

    Geerlofs, Simon H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hanna, Luke A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Judd, Chaeli R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Blake, Kara M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2012-09-01

    This fiscal year 2012 year-end report summarizes activities carried out under DOE Water Power task 2.1.7, Permitting and Planning. Activities under Task 2.1.7 address the concerns of a wide range of stakeholders with an interest in the development of the MHK industry, including regulatory and resource management agencies, tribes, NGOs, and industry.

  13. Developmental changes in using verbal self-cueing in task-switching situations: the impact of task practice and task-sequencing demands

    Science.gov (United States)

    Kray, Jutta; Gaspard, Hanna; Karbach, Julia; Blaye, Agnès

    2013-01-01

    In this study we examined whether developmental changes in using verbal self-cueing for task-goal maintenance are dependent on the amount of task practice and task-sequencing demands. To measure task-goal maintenance we applied a switching paradigm in which children either performed only task A or B in single-task blocks or switched between them on every second trial in mixed-task blocks. Task-goal maintenance was determined by comparing the performance between both blocks (mixing costs). The influence of verbal self-cueing was measured by instructing children to either name the next task aloud or not to verbalize during task preparation. Task-sequencing demands were varied between groups whereas one group received spatial task cues to support keeping track of the task sequence, while the other group did not. We also varied by the amount of prior practice in task switching while one group of participants practiced task switching first, before performing the task naming in addition, and the other group did it vice versa. Results of our study investigating younger (8–10 years) and older children (11–13 years) revealed no age differences in beneficial effects of verbal self-cueing. In line with previous findings, children showed reduced mixing costs under task-naming instructions and under conditions of low task-sequence demands (with the presence of spatial task cues). Our results also indicated that these benefits were only obtained for those groups of children that first received practice in task switching alone with no additional verbalization instruction. These findings suggest that internal task-cueing strategies can be efficiently used in children but only if they received prior practice in the underlying task so that demands on keeping and coordinating various instructions are reduced. Moreover, children benefitted from spatial task cues for better task-goal maintenance only if no verbal task-cueing strategy was introduced first. PMID:24381566

  14. Spatial Tapping Interferes With the Processing of Linguistic Spatial Relations

    NARCIS (Netherlands)

    Noordzij, Matthijs Leendert; van der Lubbe, Robert Henricus Johannes; Neggers, Sebastiaan F.W.; Postma, Albert

    2004-01-01

    Simple spatial relations may be represented either in a propositional format that is dependent on verbal rehearsal or in a picture-like format that is maintained by visual-spatial rehearsal. In sentence-picture and picture-picture verification tasks, we examined the effect of an articulatory

  15. Gestures maintain spatial imagery.

    Science.gov (United States)

    Wesp, R; Hesse, J; Keutmann, D; Wheaton, K

    2001-01-01

    Recent theories suggest alternatives to the commonly held belief that the sole role of gestures is to communicate meaning directly to listeners. Evidence suggests that gestures may serve a cognitive function for speakers, possibly acting as lexical primes. We observed that participants gestured more often when describing a picture from memory than when the picture was present and that gestures were not influenced by manipulating eye contact of a listener. We argue that spatial imagery serves a short-term memory function during lexical search and that gestures may help maintain spatial images. When spatial imagery is not necessary, as in conditions of direct visual stimulation, reliance on gestures is reduced or eliminated.

  16. Cognitive Modeling and Task Analysis: Basic Processes and Individual Differences

    National Research Council Canada - National Science Library

    Ackerman, Phillip

    1999-01-01

    ... in a complex-skill environment. The subset of task conditions selected were those that involve basic processes of working memory, task monitoring, and differential loads on spatial reasoning and speed of perceiving...

  17. Testing a Dynamic Field Account of Interactions between Spatial Attention and Spatial Working Memory

    Science.gov (United States)

    Johnson, Jeffrey S.; Spencer, John P.

    2016-01-01

    Studies examining the relationship between spatial attention and spatial working memory (SWM) have shown that discrimination responses are faster for targets appearing at locations that are being maintained in SWM, and that location memory is impaired when attention is withdrawn during the delay. These observations support the proposal that sustained attention is required for successful retention in SWM: if attention is withdrawn, memory representations are likely to fail, increasing errors. In the present study, this proposal is reexamined in light of a neural process model of SWM. On the basis of the model's functioning, we propose an alternative explanation for the observed decline in SWM performance when a secondary task is performed during retention: SWM representations drift systematically toward the location of targets appearing during the delay. To test this explanation, participants completed a color-discrimination task during the delay interval of a spatial recall task. In the critical shifting attention condition, the color stimulus could appear either toward or away from the memorized location relative to a midline reference axis. We hypothesized that if shifting attention during the delay leads to the failure of SWM representations, there should be an increase in the variance of recall errors but no change in directional error, regardless of the direction of the shift. Conversely, if shifting attention induces drift of SWM representations—as predicted by the model—there should be systematic changes in the pattern of spatial recall errors depending on the direction of the shift. Results were consistent with the latter possibility—recall errors were biased toward the location of discrimination targets appearing during the delay. PMID:26810574

  18. Testing a dynamic-field account of interactions between spatial attention and spatial working memory.

    Science.gov (United States)

    Johnson, Jeffrey S; Spencer, John P

    2016-05-01

    Studies examining the relationship between spatial attention and spatial working memory (SWM) have shown that discrimination responses are faster for targets appearing at locations that are being maintained in SWM, and that location memory is impaired when attention is withdrawn during the delay. These observations support the proposal that sustained attention is required for successful retention in SWM: If attention is withdrawn, memory representations are likely to fail, increasing errors. In the present study, this proposal was reexamined in light of a neural-process model of SWM. On the basis of the model's functioning, we propose an alternative explanation for the observed decline in SWM performance when a secondary task is performed during retention: SWM representations drift systematically toward the location of targets appearing during the delay. To test this explanation, participants completed a color discrimination task during the delay interval of a spatial-recall task. In the critical shifting-attention condition, the color stimulus could appear either toward or away from the midline reference axis, relative to the memorized location. We hypothesized that if shifting attention during the delay leads to the failure of SWM representations, there should be an increase in the variance of recall errors, but no change in directional errors, regardless of the direction of the shift. Conversely, if shifting attention induces drift of SWM representations-as predicted by the model-systematic changes in the patterns of spatial-recall errors should occur that would depend on the direction of the shift. The results were consistent with the latter possibility-recall errors were biased toward the locations of discrimination targets appearing during the delay.

  19. Age-Related Differences in Multiple Task Monitoring

    OpenAIRE

    Todorov, Ivo; Del Missier, Fabio; Mäntylä, Timo

    2014-01-01

    Coordinating multiple tasks with narrow deadlines is particularly challenging for older adults because of age related decline in cognitive control functions. We tested the hypothesis that multiple task performance reflects age- and gender-related differences in executive functioning and spatial ability. Young and older adults completed a multitasking session with four monitoring tasks as well as separate tasks measuring executive functioning and spatial ability. For both age groups, men excee...

  20. Neural Correlates of a Perspective-taking Task Using in a Realistic Three-dimmensional Environment Based Task: A Pilot Functional Magnetic Resonance Imaging Study.

    Science.gov (United States)

    Agarwal, Sri Mahavir; Shivakumar, Venkataram; Kalmady, Sunil V; Danivas, Vijay; Amaresha, Anekal C; Bose, Anushree; Narayanaswamy, Janardhanan C; Amorim, Michel-Ange; Venkatasubramanian, Ganesan

    2017-08-31

    Perspective-taking ability is an essential spatial faculty that is of much interest in both health and neuropsychiatric disorders. There is limited data on the neural correlates of perspective taking in the context of a realistic three-dimensional environment. We report the results of a pilot study exploring the same in eight healthy volunteers. Subjects underwent two runs of an experiment in a 3 Tesla magnetic resonance imaging (MRI) involving alternate blocks of a first-person perspective based allocentric object location memory task (OLMT), a third-person perspective based egocentric visual perspective taking task (VPRT), and a table task (TT) that served as a control. Difference in blood oxygen level dependant response during task performance was analyzed using Statistical Parametric Mapping software, version 12. Activations were considered significant if they survived family-wise error correction at the cluster level using a height threshold of p <0.001, uncorrected at the voxel level. A significant difference in accuracy and reaction time based on task type was found. Subjects had significantly lower accuracy in VPRT compared to TT. Accuracy in the two active tasks was not significantly different. Subjects took significantly longer in the VPRT in comparison to TT. Reaction time in the two active tasks was not significantly different. Functional MRI revealed significantly higher activation in the bilateral visual cortex and left temporoparietal junction (TPJ) in VPRT compared to OLMT. The results underscore the importance of TPJ in egocentric manipulation in healthy controls in the context of reality-based spatial tasks.

  1. Decision paths in complex tasks

    Science.gov (United States)

    Galanter, Eugene

    1991-01-01

    Complex real world action and its prediction and control has escaped analysis by the classical methods of psychological research. The reason is that psychologists have no procedures to parse complex tasks into their constituents. Where such a division can be made, based say on expert judgment, there is no natural scale to measure the positive or negative values of the components. Even if we could assign numbers to task parts, we lack rules i.e., a theory, to combine them into a total task representation. We compare here two plausible theories for the amalgamation of the value of task components. Both of these theories require a numerical representation of motivation, for motivation is the primary variable that guides choice and action in well-learned tasks. We address this problem of motivational quantification and performance prediction by developing psychophysical scales of the desireability or aversiveness of task components based on utility scaling methods (Galanter 1990). We modify methods used originally to scale sensory magnitudes (Stevens and Galanter 1957), and that have been applied recently to the measure of task 'workload' by Gopher and Braune (1984). Our modification uses utility comparison scaling techniques which avoid the unnecessary assumptions made by Gopher and Braune. Formula for the utility of complex tasks based on the theoretical models are used to predict decision and choice of alternate paths to the same goal.

  2. Mental fatigue and task control : Planning and preparation

    NARCIS (Netherlands)

    Lorist, MM; Klein, Martin; Nieuwenhuis, S; De Jong, R; Mulder, G; Meijman, TF

    The effects of mental fatigue on planning and preparation for future actions were examined, using a task switching paradigm. Fatigue was induced by "time on task," with subjects performing a switch task continuously for 2 hr. Subjects had to alternate between tasks on every second trial, so that a

  3. The SPAtial EFficiency metric (SPAEF): multiple-component evaluation of spatial patterns for optimization of hydrological models

    Science.gov (United States)

    Koch, Julian; Cüneyd Demirel, Mehmet; Stisen, Simon

    2018-05-01

    The process of model evaluation is not only an integral part of model development and calibration but also of paramount importance when communicating modelling results to the scientific community and stakeholders. The modelling community has a large and well-tested toolbox of metrics to evaluate temporal model performance. In contrast, spatial performance evaluation does not correspond to the grand availability of spatial observations readily available and to the sophisticate model codes simulating the spatial variability of complex hydrological processes. This study makes a contribution towards advancing spatial-pattern-oriented model calibration by rigorously testing a multiple-component performance metric. The promoted SPAtial EFficiency (SPAEF) metric reflects three equally weighted components: correlation, coefficient of variation and histogram overlap. This multiple-component approach is found to be advantageous in order to achieve the complex task of comparing spatial patterns. SPAEF, its three components individually and two alternative spatial performance metrics, i.e. connectivity analysis and fractions skill score, are applied in a spatial-pattern-oriented model calibration of a catchment model in Denmark. Results suggest the importance of multiple-component metrics because stand-alone metrics tend to fail to provide holistic pattern information. The three SPAEF components are found to be independent, which allows them to complement each other in a meaningful way. In order to optimally exploit spatial observations made available by remote sensing platforms, this study suggests applying bias insensitive metrics which further allow for a comparison of variables which are related but may differ in unit. This study applies SPAEF in the hydrological context using the mesoscale Hydrologic Model (mHM; version 5.8), but we see great potential across disciplines related to spatially distributed earth system modelling.

  4. Alternative wastewatersystems

    DEFF Research Database (Denmark)

    Dyck-Madsen, Søren; Hoffmann, Birgitte; Gabriel, Søren

    1999-01-01

    The report:-  Communicates experiences from Swedish buildings from the establishment and running of alternative wastewater systems. Communicates pictures of alternative buildings and wastewater systems in Sweden. Gives a short evaluation of the performance and the sustainability of the systems....

  5. When Task Conflict Becomes Personal

    Science.gov (United States)

    Guenter, Hannes; van Emmerik, Hetty; Schreurs, Bert; Kuypers, Tom; van Iterson, Ad; Notelaers, Guy

    2016-01-01

    Although potentially beneficial, task conflict may threaten teams because it often leads to relationship conflict. Prior research has identified a set of interpersonal factors (e.g., team communication, team trust) that help attenuate this association. The purpose of this article is to provide an alternative perspective that focuses on the moderating role of performance-related factors (i.e., perceived team performance). Using social identity theory, we build a model that predicts how task conflict associates with growth in relationship conflict and how perceived team performance influences this association. We test a three-wave longitudinal model by means of random coefficient growth modeling, using data from 60 ongoing teams working in a health care organization. Results provide partial support for our hypotheses. Only when perceived team performance is low, do task conflicts relate with growth in relationship conflict. We conclude that perceived team performance seems to enable teams to uncouple task from relationship conflict. PMID:28190944

  6. Age-related differences in multiple task monitoring.

    Science.gov (United States)

    Todorov, Ivo; Del Missier, Fabio; Mäntylä, Timo

    2014-01-01

    Coordinating multiple tasks with narrow deadlines is particularly challenging for older adults because of age related decline in cognitive control functions. We tested the hypothesis that multiple task performance reflects age- and gender-related differences in executive functioning and spatial ability. Young and older adults completed a multitasking session with four monitoring tasks as well as separate tasks measuring executive functioning and spatial ability. For both age groups, men exceeded women in multitasking, measured as monitoring accuracy. Individual differences in executive functioning and spatial ability were independent predictors of young adults' monitoring accuracy, but only spatial ability was related to sex differences. For older adults, age and executive functioning, but not spatial ability, predicted multitasking performance. These results suggest that executive functions contribute to multiple task performance across the adult life span and that reliance on spatial skills for coordinating deadlines is modulated by age.

  7. Age-related differences in multiple task monitoring.

    Directory of Open Access Journals (Sweden)

    Ivo Todorov

    Full Text Available Coordinating multiple tasks with narrow deadlines is particularly challenging for older adults because of age related decline in cognitive control functions. We tested the hypothesis that multiple task performance reflects age- and gender-related differences in executive functioning and spatial ability. Young and older adults completed a multitasking session with four monitoring tasks as well as separate tasks measuring executive functioning and spatial ability. For both age groups, men exceeded women in multitasking, measured as monitoring accuracy. Individual differences in executive functioning and spatial ability were independent predictors of young adults' monitoring accuracy, but only spatial ability was related to sex differences. For older adults, age and executive functioning, but not spatial ability, predicted multitasking performance. These results suggest that executive functions contribute to multiple task performance across the adult life span and that reliance on spatial skills for coordinating deadlines is modulated by age.

  8. Perceptual load affects exogenous spatial orienting while working memory load does not.

    Science.gov (United States)

    Santangelo, Valerio; Finoia, Paola; Raffone, Antonino; Belardinelli, Marta Olivetti; Spence, Charles

    2008-01-01

    We examined whether or not increasing visual perceptual load or visual working memory (WM) load would affect the exogenous orienting of visuo-spatial attention, in order to assess whether or not exogenous orienting is genuinely automatic. In Experiment 1, we manipulated visual perceptual load by means of a central morphing shape that in some trials morphed into a particular target shape (a rectangle) that participants had to detect. In Experiment 2, the possibility that the presentation of any changing stimulus at fixation would eliminate exogenous orienting was ruled out, by presenting two alternating letters at fixation. In Experiment 3, we manipulated visual WM load by means of arrays consisting of three (low-load) or five (high-load) randomly located coloured squares. The participants had to remember these items in order to judge whether a cued square had been presented in the same or different colour at the end of each trial. In all the experiments, exogenous visuo-spatial attentional orienting was measured by means of an orthogonal spatial cuing task, in which the participants had to discriminate the elevation (up vs. down) of a visual target previously cued by a spatially nonpredictive visual cue. The results showed that increasing the perceptual load of the task eliminated the exogenous orienting of visuo-spatial attention. By contrast, increasing the WM load had no effect on spatial orienting. These results are discussed in terms of the light that they shed on claims regarding the automaticity of visuo-spatial exogenous orienting.

  9. Task-set inertia and memory-consolidation bottleneck in dual tasks.

    Science.gov (United States)

    Koch, Iring; Rumiati, Raffaella I

    2006-11-01

    Three dual-task experiments examined the influence of processing a briefly presented visual object for deferred verbal report on performance in an unrelated auditory-manual reaction time (RT) task. RT was increased at short stimulus-onset asynchronies (SOAs) relative to long SOAs, showing that memory consolidation processes can produce a functional processing bottleneck in dual-task performance. In addition, the experiments manipulated the spatial compatibility of the orientation of the visual object and the side of the speeded manual response. This cross-task compatibility produced relative RT benefits only when the instruction for the visual task emphasized overlap at the level of response codes across the task sets (Experiment 1). However, once the effective task set was in place, it continued to produce cross-task compatibility effects even in single-task situations ("ignore" trials in Experiment 2) and when instructions for the visual task did not explicitly require spatial coding of object orientation (Experiment 3). Taken together, the data suggest a considerable degree of task-set inertia in dual-task performance, which is also reinforced by finding costs of switching task sequences (e.g., AC --> BC vs. BC --> BC) in Experiment 3.

  10. How alternative are alternative fuels?

    OpenAIRE

    Soffritti, Tiziana; Danielis, Romeo

    1998-01-01

    Could alternative fuel vehicles contribute to a substantial reduction of air pollution? Is there a market for alternative fuel vehicles? Could a market be created via a pollution tax? The article answers these questions on the basis of the available estimates.

  11. Alternative detox.

    Science.gov (United States)

    Ernst, E

    2012-01-01

    The concept that alternative therapies can eliminate toxins and toxicants from the body, i.e. 'alternative detox' (AD) is popular. Selected textbooks and articles on the subject of AD. The principles of AD make no sense from a scientific perspective and there is no clinical evidence to support them. The promotion of AD treatments provides income for some entrepreneurs but has the potential to cause harm to patients and consumers. In alternative medicine, simplistic but incorrect concepts such as AD abound. AREAS TIMELY FOR RESEARCH: All therapeutic claims should be scientifically tested before being advertised-and AD cannot be an exception.

  12. Order information in verbal working memory shifts the subjective midpoint in both the line bisection and the landmark tasks.

    Science.gov (United States)

    Antoine, Sophie; Ranzini, Mariagrazia; Gebuis, Titia; van Dijck, Jean-Philippe; Gevers, Wim

    2017-10-01

    A largely substantiated view in the domain of working memory is that the maintenance of serial order is achieved by generating associations of each item with an independent representation of its position, so-called position markers. Recent studies reported that the ordinal position of an item in verbal working memory interacts with spatial processing. This suggests that position markers might be spatial in nature. However, these interactions were so far observed in tasks implying a clear binary categorization of space (i.e., with left and right responses or targets). Such binary categorizations leave room for alternative interpretations, such as congruency between non-spatial categorical codes for ordinal position (e.g., begin and end) and spatial categorical codes for response (e.g., left and right). Here we discard this interpretation by providing evidence that this interaction can also be observed in a task that draws upon a continuous processing of space, the line bisection task. Specifically, bisections are modulated by ordinal position in verbal working memory, with lines bisected more towards the right after retrieving items from the end compared to the beginning of the memorized sequence. This supports the idea that position markers are intrinsically spatial in nature.

  13. Prioritization of sediment management alternatives using stochastic multicriteria acceptability analysis

    International Nuclear Information System (INIS)

    Alvarez-Guerra, Manuel; Canis, Laure; Voulvoulis, Nikolaos; Viguri, Javier R.; Linkov, Igor

    2010-01-01

    Decision-making for sediment management is a complex task that requires the consideration of temporal and spatial impacts of several remedial alternatives as well as the associated economic, social and political impact. Multicriteria decision analysis (MCDA) is becoming increasingly recognized as an important environmental management tool that can be used to support the selection of suitable remediation alternatives and prioritization of management units in space and time. This paper proposes an MCDA framework for prioritizing sediment management alternatives. This framework involves identifying of a set of feasible options, as well as defining and evaluating criteria which integrate relevant technical, economic, social and environmental aspects of remedies. The methodology allows an explicit consideration of uncertainty in criteria scores and weights by assigning probability distributions and analyzing subsequent Monte-Carlo simulations. The consideration of different stakeholder simulated values is used to assess the robustness of alternative rankings and to guide the selection of remediation options. An application of this methodology to a case study in the Bay of Santander, Spain, is presented. An assessment is conducted for the case of unknown preferences as well as for hypothetical preferences profiles for four types of stakeholders: Idealist, Politician, Environmentalist and Balanced. The results are used to visualize stakeholder positions and potential disagreements, allowing for the identification of a group of least preferred alternatives for each stakeholder. Stakeholder involvement has the potential to ease the remedy selection process during all stages of the decision-making process and to eventually remedy implementation.

  14. Evidence for an alternation strategy in time-place learning.

    Science.gov (United States)

    Pizzo, Matthew J; Crystal, Jonathon D

    2004-11-30

    Many different conclusions concerning what type of mechanism rats use to solve a daily time-place task have emerged in the literature. The purpose of this study was to test three competing explanations of time-place discrimination. Rats (n = 10) were tested twice daily in a T-maze, separated by approximately 7 h. Food was available at one location in the morning and another location in the afternoon. After the rats learned to visit each location at the appropriate time, tests were omitted to evaluate whether the rats were utilizing time-of-day (i.e., a circadian oscillator) or an alternation strategy (i.e., visiting a correct location is a cue to visit the next location). Performance on this test was significantly lower than chance, ruling out the use of time-of-day. A phase advance of the light cycle was conducted to test the alternation strategy and timing with respect to the light cycle (i.e., an interval timer). There was no difference between probe and baseline performance. These results suggest that the rats used an alternation strategy to meet the temporal and spatial contingencies in the time-place task.

  15. A dose–response study of the effects of pre-test administration of beta-adrenergic receptor antagonist propranolol on the learning of active place avoidance, a spatial cognition task, in rats

    Czech Academy of Sciences Publication Activity Database

    Stuchlík, Aleš; Petrásek, Tomáš; Valeš, Karel

    2009-01-01

    Roč. 200, č. 1 (2009), s. 144-149 ISSN 0166-4328 R&D Projects: GA ČR(CZ) GA309/07/0341; GA ČR(CZ) GA309/09/0286 Institutional research plan: CEZ:AV0Z50110509 Keywords : propranolol * learning * spatial memory Subject RIV: FH - Neuro logy Impact factor: 3.220, year: 2009

  16. Cosmic alternatives?

    Science.gov (United States)

    Gregory, Ruth

    2009-04-01

    "Cosmologists are often in error but never in doubt." This pithy characterization by the Soviet physicist Lev Landau sums up the raison d'être of Facts and Speculations in Cosmology. Authors Jayant Narlikar and Geoffrey Burbidge are proponents of a "steady state" theory of cosmology, and they argue that the cosmological community has become fixated on a "Big Bang" dogma, suppressing alternative viewpoints. This book very much does what it says on the tin: it sets out what is known in cosmology, and puts forward the authors' point of view on an alternative to the Big Bang.

  17. A new semantic vigilance task: vigilance decrement, workload, and sensitivity to dual-task costs.

    Science.gov (United States)

    Epling, Samantha L; Russell, Paul N; Helton, William S

    2016-01-01

    Cognitive resource theory is a common explanation for both the performance decline in vigilance tasks, known as the vigilance decrement, and the limited ability to perform multiple tasks simultaneously. The limited supply of cognitive resources may be utilized faster than they are replenished resulting in a performance decrement, or may need to be allocated among multiple tasks with some performance cost. Researchers have proposed both domain-specific, for example spatial versus verbal processing resources, and domain general cognitive resources. One challenge in testing the domain specificity of cognitive resources in vigilance is the current lack of difficult semantic vigilance tasks which reliably produce a decrement. In the present research, we investigated whether the vigilance decrement was found in a new abbreviated semantic discrimination vigilance task, and whether there was a performance decrement in said vigilance task when paired with a word recall task, as opposed to performed individually. As hypothesized, a vigilance decrement in the semantic vigilance task was found in both the single-task and dual-task conditions, along with reduced vigilance performance in the dual-task condition and reduced word recall in the dual-task condition. This is consistent with cognitive resource theory. The abbreviated semantic vigilance task will be a useful tool for researchers interested in determining the specificity of cognitive resources utilized in vigilance tasks.

  18. Task-driven image acquisition and reconstruction in cone-beam CT

    International Nuclear Information System (INIS)

    Gang, Grace J; Stayman, J Webster; Siewerdsen, Jeffrey H; Ehtiati, Tina

    2015-01-01

    This work introduces a task-driven imaging framework that incorporates a mathematical definition of the imaging task, a model of the imaging system, and a patient-specific anatomical model to prospectively design image acquisition and reconstruction techniques to optimize task performance. The framework is applied to joint optimization of tube current modulation, view-dependent reconstruction kernel, and orbital tilt in cone-beam CT. The system model considers a cone-beam CT system incorporating a flat-panel detector and 3D filtered backprojection and accurately describes the spatially varying noise and resolution over a wide range of imaging parameters in the presence of a realistic anatomical model. Task-based detectability index (d′) is incorporated as the objective function in a task-driven optimization of image acquisition and reconstruction techniques. The orbital tilt was optimized through an exhaustive search across tilt angles ranging ±30°. For each tilt angle, the view-dependent tube current and reconstruction kernel (i.e. the modulation profiles) that maximized detectability were identified via an alternating optimization. The task-driven approach was compared with conventional unmodulated and automatic exposure control (AEC) strategies for a variety of imaging tasks and anthropomorphic phantoms. The task-driven strategy outperformed the unmodulated and AEC cases for all tasks. For example, d′ for a sphere detection task in a head phantom was improved by 30% compared to the unmodulated case by using smoother kernels for noisy views and distributing mAs across less noisy views (at fixed total mAs) in a manner that was beneficial to task performance. Similarly for detection of a line-pair pattern, the task-driven approach increased d′ by 80% compared to no modulation by means of view-dependent mA and kernel selection that yields modulation transfer function and noise-power spectrum optimal to the task. Optimization of orbital tilt identified the

  19. Growing Alternatives

    DEFF Research Database (Denmark)

    Bagger-Petersen, Mai Corlin

    2014-01-01

    From 2014, Anhui Province will pilot a reform of the residential land market in China, thus integrating rural Anhui in the national housing market. In contrast, artist and activist Ou Ning has proposed the Bishan time money currency, intending to establish an alternative economic circuit in Bishan...

  20. Alternative Veier

    DEFF Research Database (Denmark)

    Kruse, Tove Elisabeth; Salamonsen, Anita

    reflektioner omkring patienters brug af og erfaringer med alternativ behandling. Patientorganisationer, organisatoner for alternative behandlere og organisationer for læger og medicinstuderende har læst bogens patienthistorier og deres perspektiver lægges frem. Til slut i bogen diskuteres betydningen af de...

  1. Validation of the human odor span task: effects of nicotine.

    Science.gov (United States)

    MacQueen, David A; Drobes, David J

    2017-10-01

    Amongst non-smokers, nicotine generally enhances performance on tasks of attention, with limited effect on working memory. In contrast, nicotine has been shown to produce robust enhancements of working memory in non-humans. To address this gap, the present study investigated the effects of nicotine on the performance of non-smokers on a cognitive battery which included a working memory task reverse-translated from use with rodents (the odor span task, OST). Nicotine has been reported to enhance OST performance in rats and the present study assessed whether this effect generalizes to human performance. Thirty non-smokers were tested on three occasions after consuming either placebo, 2 mg, or 4 mg nicotine gum. On each occasion, participants completed a battery of clinical and experimental tasks of working memory and attention. Nicotine was associated with dose-dependent enhancements in sustained attention, as evidenced by increased hit accuracy on the rapid visual information processing (RVIP) task. However, nicotine failed to produce main effects on OST performance or on alternative measures of working memory (digit span, spatial span, letter-number sequencing, 2-back) or attention (digits forward, 0-back). Interestingly, enhancement of RVIP performance occurred concomitant to significant reductions in self-reported attention/concentration. Human OST performance was significantly related to N-back performance, and as in rodents, OST accuracy declined with increasing memory load. Given the similarity of human and rodent OST performance under baseline conditions and the strong association between OST and visual 0-back accuracy, the OST may be particular useful in the study of conditions characterized by inattention.

  2. Spatial Operations

    Directory of Open Access Journals (Sweden)

    Anda VELICANU

    2010-09-01

    Full Text Available This paper contains a brief description of the most important operations that can be performed on spatial data such as spatial queries, create, update, insert, delete operations, conversions, operations on the map or analysis on grid cells. Each operation has a graphical example and some of them have code examples in Oracle and PostgreSQL.

  3. Spatializing Time

    DEFF Research Database (Denmark)

    Thomsen, Bodil Marie Stavning

    2011-01-01

    The article analyses some of artist Søren Lose's photographic installations in which time, history and narration is reflected in the creation of allegoric, spatial relations.......The article analyses some of artist Søren Lose's photographic installations in which time, history and narration is reflected in the creation of allegoric, spatial relations....

  4. Spatial Computation

    Science.gov (United States)

    2003-12-01

    Computation and today’s microprocessors with the approach to operating system architecture, and the controversy between microkernels and monolithic kernels...Both Spatial Computation and microkernels break away a relatively monolithic architecture into in- dividual lightweight pieces, well specialized...for their particular functionality. Spatial Computation removes global signals and control, in the same way microkernels remove the global address

  5. Are factors related to dual-task performance in people with Parkinson's disease dependent on the type of dual task?

    Science.gov (United States)

    Strouwen, Carolien; Molenaar, Esther A L M; Keus, Samyra H J; Münks, Liesbeth; Heremans, Elke; Vandenberghe, Wim; Bloem, Bastiaan R; Nieuwboer, Alice

    2016-02-01

    Impaired dual-task performance significantly impacts upon functional mobility in people with Parkinson's disease (PD). The aim of this study was to identify determinants of dual-task performance in people with PD in three different dual tasks to assess their possible task-dependency. We recruited 121 home-dwelling patients with PD (mean age 65.93 years; mean disease duration 8.67 years) whom we subjected to regular walking (control condition) and to three dual-task conditions: walking combined with a backwards Digit Span task, an auditory Stroop task and a Mobile Phone task. We measured dual-task gait velocity using the GAITRite mat and dual-task reaction times and errors on the concurrent tasks as outcomes. Motor, cognitive and descriptive variables which correlated to dual-task performance (p task gait velocity and executive function, tested by the alternating intake test, was significantly associated with gait velocity during the Digit Span (R(2) = 0.65; p task (R(2) = 0.62; p task. Age was a surplus determinant of gait velocity while using a mobile phone. Single-task gait velocity and executive function as measured by a verbal fluency switching task were independent determinants of dual-task gait performance in people with PD. In contrast to expectation, these factors were the same across different tasks, supporting the robustness of the findings. Future study needs to determine whether these factors predict dual-task abnormalities prospectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. The role of visual spatial attention in adult developmental dyslexia.

    Science.gov (United States)

    Collis, Nathan L; Kohnen, Saskia; Kinoshita, Sachiko

    2013-01-01

    The present study investigated the nature of visual spatial attention deficits in adults with developmental dyslexia, using a partial report task with five-letter, digit, and symbol strings. Participants responded by a manual key press to one of nine alternatives, which included other characters in the string, allowing an assessment of position errors as well as intrusion errors. The results showed that the dyslexic adults performed significantly worse than age-matched controls with letter and digit strings but not with symbol strings. Both groups produced W-shaped serial position functions with letter and digit strings. The dyslexics' deficits with letter string stimuli were limited to position errors, specifically at the string-interior positions 2 and 4. These errors correlated with letter transposition reading errors (e.g., reading slat as "salt"), but not with the Rapid Automatized Naming (RAN) task. Overall, these results suggest that the dyslexic adults have a visual spatial attention deficit; however, the deficit does not reflect a reduced span in visual-spatial attention, but a deficit in processing a string of letters in parallel, probably due to difficulty in the coding of letter position.

  7. Plasticity of Human Spatial Cognition: Spatial Language and Cognition Covary across Cultures

    Science.gov (United States)

    Haun, Daniel B. M.; Rapold, Christian J.; Janzen, Gabriele; Levinson, Stephen C.

    2011-01-01

    The present paper explores cross-cultural variation in spatial cognition by comparing spatial reconstruction tasks by Dutch and Namibian elementary school children. These two communities differ in the way they predominantly express spatial relations in language. Four experiments investigate cognitive strategy preferences across different levels of…

  8. Spatial Working Memory Interferes with Explicit, but Not Probabilistic Cuing of Spatial Attention

    Science.gov (United States)

    Won, Bo-Yeong; Jiang, Yuhong V.

    2015-01-01

    Recent empirical and theoretical work has depicted a close relationship between visual attention and visual working memory. For example, rehearsal in spatial working memory depends on spatial attention, whereas adding a secondary spatial working memory task impairs attentional deployment in visual search. These findings have led to the proposal…

  9. Energy alternatives

    International Nuclear Information System (INIS)

    Sweet, C.

    1987-01-01

    The designated successor to fossil fuels is nuclear fission/fusion and that turns out to be problematic. Alternative Energy Systems have great potential but political forces seem to be hampering their development and introduction. The technologies are flexible in their use and scale of operation. The learning curve will not be short but neither will it be as long and as costly as nuclear power. It is time that this is recognised and some serious rethinking takes place in what presently passes for energy policies both in the industrialised countries and in the Third World. Alternative energy systems are defined and some of them which are relevant to the United Kingdom are discussed. (author)

  10. Detecting spatial memory deficits beyond blindness in tg2576 Alzheimer mice.

    Science.gov (United States)

    Yassine, Nour; Lazaris, Anelise; Dorner-Ciossek, Cornelia; Després, Olivier; Meyer, Laurence; Maitre, Michel; Mensah-Nyagan, Ayikoe Guy; Cassel, Jean-Christophe; Mathis, Chantal

    2013-03-01

    The retinal degeneration Pde6b(rd1) (rd) mutation can be a major pitfall in behavioral studies using tg2576 mice bred on a B6:SJL genetic background, 1 of the most widely used models of Alzheimer's disease. After a pilot study in wild type mice, performance of 8- and 16-month-old tg2576 mice were assessed in several behavioral tasks with the challenge of selecting 1 or more task(s) showing robust memory deficits on this genetic background. Water maze acquisition was impossible in rd homozygotes, whereas Y-maze alternation, object recognition, and olfactory discrimination were unaffected by both the transgene and the rd mutation. Spatial memory retention of 8- and 16-month-old tg2576 mice, however, was dramatically affected independently of the rd mutation when mice had to recognize a spatial configuration of objects or to perform the Barnes maze. Thus, the latter tasks appear extremely useful to evaluate spatial memory deficits and to test cognitive therapies in tg2576 mice and other mouse models bred on a background susceptible to visual impairment. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Spatial dependencies between large-scale brain networks.

    Directory of Open Access Journals (Sweden)

    Robert Leech

    Full Text Available Functional neuroimaging reveals both increases (task-positive and decreases (task-negative in neural activation with many tasks. Many studies show a temporal relationship between task positive and task negative networks that is important for efficient cognitive functioning. Here we provide evidence for a spatial relationship between task positive and negative networks. There are strong spatial similarities between many reported task negative brain networks, termed the default mode network, which is typically assumed to be a spatially fixed network. However, this is not the case. The spatial structure of the DMN varies depending on what specific task is being performed. We test whether there is a fundamental spatial relationship between task positive and negative networks. Specifically, we hypothesize that the distance between task positive and negative voxels is consistent despite different spatial patterns of activation and deactivation evoked by different cognitive tasks. We show significantly reduced variability in the distance between within-condition task positive and task negative voxels than across-condition distances for four different sensory, motor and cognitive tasks--implying that deactivation patterns are spatially dependent on activation patterns (and vice versa, and that both are modulated by specific task demands. We also show a similar relationship between positively and negatively correlated networks from a third 'rest' dataset, in the absence of a specific task. We propose that this spatial relationship may be the macroscopic analogue of microscopic neuronal organization reported in sensory cortical systems, and that this organization may reflect homeostatic plasticity necessary for efficient brain function.

  12. Task-based statistical image reconstruction for high-quality cone-beam CT

    Science.gov (United States)

    Dang, Hao; Webster Stayman, J.; Xu, Jennifer; Zbijewski, Wojciech; Sisniega, Alejandro; Mow, Michael; Wang, Xiaohui; Foos, David H.; Aygun, Nafi; Koliatsos, Vassilis E.; Siewerdsen, Jeffrey H.

    2017-11-01

    Task-based analysis of medical imaging performance underlies many ongoing efforts in the development of new imaging systems. In statistical image reconstruction, regularization is often formulated in terms to encourage smoothness and/or sharpness (e.g. a linear, quadratic, or Huber penalty) but without explicit formulation of the task. We propose an alternative regularization approach in which a spatially varying penalty is determined that maximizes task-based imaging performance at every location in a 3D image. We apply the method to model-based image reconstruction (MBIR—viz., penalized weighted least-squares, PWLS) in cone-beam CT (CBCT) of the head, focusing on the task of detecting a small, low-contrast intracranial hemorrhage (ICH), and we test the performance of the algorithm in the context of a recently developed CBCT prototype for point-of-care imaging of brain injury. Theoretical predictions of local spatial resolution and noise are computed via an optimization by which regularization (specifically, the quadratic penalty strength) is allowed to vary throughout the image to maximize local task-based detectability index ({{d}\\prime} ). Simulation studies and test-bench experiments were performed using an anthropomorphic head phantom. Three PWLS implementations were tested: conventional (constant) penalty; a certainty-based penalty derived to enforce constant point-spread function, PSF; and the task-based penalty derived to maximize local detectability at each location. Conventional (constant) regularization exhibited a fairly strong degree of spatial variation in {{d}\\prime} , and the certainty-based method achieved uniform PSF, but each exhibited a reduction in detectability compared to the task-based method, which improved detectability up to ~15%. The improvement was strongest in areas of high attenuation (skull base), where the conventional and certainty-based methods tended to over-smooth the data. The task-driven reconstruction method presents a

  13. Hippocampal insulin microinjection and in vivo microdialysis during spatial memory testing.

    Science.gov (United States)

    McNay, Ewan C; Sandusky, Leslie A; Pearson-Leary, Jiah

    2013-01-11

    Glucose metabolism is a useful marker for local neural activity, forming the basis of methods such as 2-deoxyglucose and functional magnetic resonance imaging. However, use of such methods in animal models requires anesthesia and hence both alters the brain state and prevents behavioral measures. An alternative method is the use of in vivo microdialysis to take continuous measurement of brain extracellular fluid concentrations of glucose, lactate, and related metabolites in awake, unrestrained animals. This technique is especially useful when combined with tasks designed to rely on specific brain regions and/or acute pharmacological manipulation; for example, hippocampal measurements during a spatial working memory task (spontaneous alternation) show a dip in extracellular glucose and rise in lactate that are suggestive of enhanced glycolysis, and intrahippocampal insulin administration both improves memory and increases hippocampal glycolysis. Substances such as insulin can be delivered to the hippocampus via the same microdialysis probe used to measure metabolites. The use of spontaneous alternation as a measure of hippocampal function is designed to avoid any confound from stressful motivators (e.g. footshock), restraint, or rewards (e.g. food), all of which can alter both task performance and metabolism; this task also provides a measure of motor activity that permits control for nonspecific effects of treatment. Combined, these methods permit direct measurement of the neurochemical and metabolic variables regulating behavior.

  14. Cognitive task analysis

    NARCIS (Netherlands)

    Schraagen, J.M.C.

    2000-01-01

    Cognitive task analysis is defined as the extension of traditional task analysis techniques to yield information about the knowledge, thought processes and goal structures that underlie observable task performance. Cognitive task analyses are conducted for a wide variety of purposes, including the

  15. Spatial Theography

    OpenAIRE

    van Noppen, Jean Pierre

    1995-01-01

    Descriptive theology («theography») frequently resorts to metaphorical modes of meaning. Among these metaphors, the spatial language of localization and orientation plays an important role to delineate tentative insights into the relationship between the human and the divine. These spatial metaphors are presumably based on the universal human experience of interaction between the body and its environment. It is dangerous, however, to postulate universal agreement on meanings associated with s...

  16. Different Neuroplasticity for Task Targets and Distractors

    Science.gov (United States)

    Spingath, Elsie Y.; Kang, Hyun Sug; Plummer, Thane; Blake, David T.

    2011-01-01

    Adult learning-induced sensory cortex plasticity results in enhanced action potential rates in neurons that have the most relevant information for the task, or those that respond strongly to one sensory stimulus but weakly to its comparison stimulus. Current theories suggest this plasticity is caused when target stimulus evoked activity is enhanced by reward signals from neuromodulatory nuclei. Prior work has found evidence suggestive of nonselective enhancement of neural responses, and suppression of responses to task distractors, but the differences in these effects between detection and discrimination have not been directly tested. Using cortical implants, we defined physiological responses in macaque somatosensory cortex during serial, matched, detection and discrimination tasks. Nonselective increases in neural responsiveness were observed during detection learning. Suppression of responses to task distractors was observed during discrimination learning, and this suppression was specific to cortical locations that sampled responses to the task distractor before learning. Changes in receptive field size were measured as the area of skin that had a significant response to a constant magnitude stimulus, and these areal changes paralleled changes in responsiveness. From before detection learning until after discrimination learning, the enduring changes were selective suppression of cortical locations responsive to task distractors, and nonselective enhancement of responsiveness at cortical locations selective for target and control skin sites. A comparison of observations in prior studies with the observed plasticity effects suggests that the non-selective response enhancement and selective suppression suffice to explain known plasticity phenomena in simple spatial tasks. This work suggests that differential responsiveness to task targets and distractors in primary sensory cortex for a simple spatial detection and discrimination task arise from nonselective

  17. Different neuroplasticity for task targets and distractors.

    Directory of Open Access Journals (Sweden)

    Elsie Y Spingath

    2011-01-01

    Full Text Available Adult learning-induced sensory cortex plasticity results in enhanced action potential rates in neurons that have the most relevant information for the task, or those that respond strongly to one sensory stimulus but weakly to its comparison stimulus. Current theories suggest this plasticity is caused when target stimulus evoked activity is enhanced by reward signals from neuromodulatory nuclei. Prior work has found evidence suggestive of nonselective enhancement of neural responses, and suppression of responses to task distractors, but the differences in these effects between detection and discrimination have not been directly tested. Using cortical implants, we defined physiological responses in macaque somatosensory cortex during serial, matched, detection and discrimination tasks. Nonselective increases in neural responsiveness were observed during detection learning. Suppression of responses to task distractors was observed during discrimination learning, and this suppression was specific to cortical locations that sampled responses to the task distractor before learning. Changes in receptive field size were measured as the area of skin that had a significant response to a constant magnitude stimulus, and these areal changes paralleled changes in responsiveness. From before detection learning until after discrimination learning, the enduring changes were selective suppression of cortical locations responsive to task distractors, and nonselective enhancement of responsiveness at cortical locations selective for target and control skin sites. A comparison of observations in prior studies with the observed plasticity effects suggests that the non-selective response enhancement and selective suppression suffice to explain known plasticity phenomena in simple spatial tasks. This work suggests that differential responsiveness to task targets and distractors in primary sensory cortex for a simple spatial detection and discrimination task arise from

  18. Alternative detente

    International Nuclear Information System (INIS)

    Soper, K.; Ryle, M.

    1988-01-01

    The influence of the Chernobyl accident on the disarmament and anti-nuclear movements is discussed. The accident directed attention towards the areas in common rather than the areas of disagreement. It also demonstrated the environmental impact of radioactivity, strengthening the ecological case of the anti-nuclear movement. The issues are discussed for the Western and Eastern bloc countries and the relationship between the two. Sections focus on the Eco-protest, Green politics and economics and on the politics of minority protest and the Green alternative. (U.K.)

  19. Re-examining the automaticity and directionality of the activation of the spatial-valence "good is up" metaphoric association.

    Directory of Open Access Journals (Sweden)

    Yanli Huang

    Full Text Available According to the Conceptual Metaphor Theory, people understand abstract concepts depending on the activation of more concrete concepts, but not vice versa. The present research aims to investigate the role of directionality and automaticity regarding the activation of the conceptual metaphor "good is up". Experiment 1 tested the automaticity of the spatial-to-valence metaphoric congruency effect by having participants judge the valence of a positive or negative word that appeared either at the top or at the bottom of the screen. They performed the task concurrently with a 6-digit verbal rehearsal task in the working-memory-load (WML blocks and without this task in the non-WML blocks. The spatial-to-valence metaphoric congruency effect occurred for the positive words in the non-WML blocks (i.e., positive words are judged more quickly when they appeared at the top than at the bottom of the screen, but not in the WML blocks, suggesting that this metaphoric association might not be activated automatically. Experiments 2-6 investigated the valence-to-spatial metaphoric association and its automaticity. Participants processed a positive or negative prime, which appeared at the center of the screen, and then identified a letter (p/q that subsequently appeared at the top or bottom of the screen. The valence-to-spatial metaphoric congruency effect did not occur in the WML (6-digit verbal rehearsal or non-WML blocks, whether response modality to the prime was key-press or vocal, or whether the prime was a word or a picture. The effect only unexpectedly occurred when the task was simultaneously performed with a 4-dot-position visuospatial rehearsal task. Nevertheless, the data collapsed across multiple experiments showed a null valence-to-spatial metaphoric congruency effect, suggesting the absence of the valence-to-spatial metaphoric association in general. The implications of the current findings for the Conceptual Metaphor Theory and its alternatives

  20. When predictions take control: The effect of task predictions on task switching performance

    Directory of Open Access Journals (Sweden)

    Wout eDuthoo

    2012-08-01

    Full Text Available In this paper, we aimed to investigate the role of self-generated predictions in the flexible control of behaviour. Therefore, we ran a task switching experiment in which participants were asked to try to predict the upcoming task in three conditions varying in switch rate (30%, 50% and 70%. Irrespective of their predictions, the colour of the target indicated which task participants had to perform. In line with previous studies (Mayr, 2006; Monsell & Mizon, 2006, the switch cost was attenuated as the switch rate increased. Importantly, a clear task repetition bias was found in all conditions, yet the task repetition prediction rate dropped from 78% over 66% to 49% with increasing switch probability in the three conditions. Irrespective of condition, the switch cost was strongly reduced in expectation of a task alternation compared to the cost of an unexpected task alternation following repetition predictions. Hence, our data suggest that the reduction in the switch cost with increasing switch probability is caused by a diminished expectancy for the task to repeat. Taken together, this paper highlights the importance of predictions in the flexible control of behaviour, and suggests a crucial role for task repetition expectancy in the context-sensitive adjusting of task switching performance.

  1. Alternative crops

    International Nuclear Information System (INIS)

    Andreasen, L.M.; Boon, A.D.

    1992-01-01

    Surplus cereal production in the EEC and decreasing product prices, mainly for cereals, has prompted considerable interest for new earnings in arable farming. The objective was to examine whether suggested new crops (fibre, oil, medicinal and alternative grains crops) could be considered as real alternatives. Whether a specific crop can compete economically with cereals and whether there is a market demand for the crop is analyzed. The described possibilities will result in ca. 50,000 hectares of new crops. It is expected that they would not immediately provide increased earnings, but in the long run expected price developments are more positive than for cereals. The area for new crops will not solve the current surplus cereal problem as the area used for new crops is only 3% of that used for cereals. Preconditions for many new crops is further research activities and development work as well as the establishment of processing units and organizational initiatives. Presumably, it is stated, there will then be a basis for a profitable production of new crops for some farmers. (AB) (47 refs.)

  2. Central executive involvement in children's spatial memory.

    Science.gov (United States)

    Ang, Su Yin; Lee, Kerry

    2008-11-01

    Previous research with adults found that spatial short-term and working memory tasks impose similar demands on executive resources. We administered spatial short-term and working memory tasks to 8- and 11-year-olds in three separate experiments. In Experiments 1 and 2 an executive suppression task (random number generation) was found to impair performances on a short-term memory task (Corsi blocks), a working memory task (letter rotation), and a spatial visualisation task (paper folding). In Experiment 3 an articulatory suppression task only impaired performance on the working memory task. These results suggest that short-term and working memory performances are dependent on executive resources. The degree to which the short-term memory task was dependent on executive resources was expected to be related to the amount of experience children have had with such tasks. Yet we found no significant age-related suppression effects. This was attributed to differences in employment of cognitive strategies by the older children.

  3. Error Sonification of a Complex Motor Task

    Directory of Open Access Journals (Sweden)

    Riener Robert

    2011-12-01

    Full Text Available Visual information is mainly used to master complex motor tasks. Thus, additional information providing augmented feedback should be displayed in other modalities than vision, e.g. hearing. The present work evaluated the potential of error sonification to enhance learning of a rowing-type motor task. In contrast to a control group receiving self-controlled terminal feedback, the experimental group could not significantly reduce spatial errors. Thus, motor learning was not enhanced by error sonification, although during the training the participant could benefit from it. It seems that the motor task was too slow, resulting in immediate corrections of the movement rather than in an internal representation of the general characteristics of the motor task. Therefore, further studies should elaborate the impact of error sonification when general characteristics of the motor tasks are already known.

  4. Energy alternatives

    International Nuclear Information System (INIS)

    1981-01-01

    English. A special committe of the Canadian House of Commons was established on 23 May 1980 to investigate the use of alternative energy sources such as 'gasohol', liquified coal, solar energy, methanol, wind and tidal power, biomass, and propane. In its final report, the committee envisions an energy system for Canada based on hydrogen and electricity, using solar and geothermal energy for low-grade heat. The committe was not able to say which method of generating electricty would dominate in the next century, although it recommends that fossil fuels should not be used. The fission process is not specifically discussed, but the outlook for fusion was investigated, and continued governmental support of fusion research is recommended. The report proposes some improvements in governmental energy organizations and programs

  5. NRC inspection alternatives. A study report

    International Nuclear Information System (INIS)

    Conver, S.K.; Legasey, E.E.; LeDoux, J.C.; Rehfuss, C.

    1977-04-01

    IE's efforts in pursuing various resident inspection concepts are consistent with the stated interests of the new Administration in improving federal oversight of the nuclear industry. Four alternative resident inspection concepts are described and evaluated vis-a-vis the current program. The concept of full-time onsite inspectors as a preferred alternative is discussed. The tasks necessary to implement this preferred alternative are described

  6. Task-Analytic Design of Graphic Presentations

    Science.gov (United States)

    1990-05-18

    efficiency, and reliability of a set of available cars. (ConsumerReport (DOMAINSETS (VALUE (car NOMINAL 10) (make NOMINAL ( honda nissan toyota )) (model NOMINAL...important premise of Larkin and Simon’s work is that, when comparing alternative presentations, it is fruitful to characterize graphic-based problem solving...practical real-world tasks. Chapter 6 describes an experiment in which participants were asked to use a set of alternative presertations to compare

  7. Task demand, task management, and teamwork

    Energy Technology Data Exchange (ETDEWEB)

    Braarud, Per Oeivind; Brendryen, Haavar

    2001-03-15

    The current approach to mental workload assessment in process control was evaluated in 3 previous HAMMLAB studies, by analysing the relationship between workload related measures and performance. The results showed that subjective task complexity rating was related to team's control room performance, that mental effort (NASA-TLX) was weakly related to performance, and that overall activity level was unrelated to performance. The results support the argument that general cognitive measures, i.e., mental workload, are weakly related to performance in the process control domain. This implies that other workload concepts than general mental workload are needed for valid assessment of human reliability and for valid assessment of control room configurations. An assessment of task load in process control suggested that how effort is used to handle task demand is more important then the level of effort invested to solve the task. The report suggests two main workload related concepts with a potential as performance predictors in process control: task requirements, and the work style describing how effort is invested to solve the task. The task requirements are seen as composed of individual task demand and team demand. In a similar way work style are seen as composed of individual task management and teamwork style. A framework for the development of the concepts is suggested based on a literature review and experiences from HAMMLAB research. It is suggested that operational definitions of workload concepts should be based on observable control room behaviour, to assure a potential for developing performance-shaping factors. Finally an explorative analysis of teamwork measures and performance in one study indicated that teamwork concepts are related to performance. This lends support to the suggested development of team demand and teamwork style as elements of a framework for the analysis of workload in process control. (Author)

  8. Toward Accessing Spatial Structure from Building Information Models

    Science.gov (United States)

    Schultz, C.; Bhatt, M.

    2011-08-01

    Data about building designs and layouts is becoming increasingly more readily available. In the near future, service personal (such as maintenance staff or emergency rescue workers) arriving at a building site will have immediate real-time access to enormous amounts of data relating to structural properties, utilities, materials, temperature, and so on. The critical problem for users is the taxing and error prone task of interpreting such a large body of facts in order to extract salient information. This is necessary for comprehending a situation and deciding on a plan of action, and is a particularly serious issue in time-critical and safety-critical activities such as firefighting. Current unifying building models such as the Industry Foundation Classes (IFC), while being comprehensive, do not directly provide data structures that focus on spatial reasoning and spatial modalities that are required for high-level analytical tasks. The aim of the research presented in this paper is to provide computational tools for higher level querying and reasoning that shift the cognitive burden of dealing with enormous amounts of data away from the user. The user can then spend more energy and time in planning and decision making in order to accomplish the tasks at hand. We present an overview of our framework that provides users with an enhanced model of "built-up space". In order to test our approach using realistic design data (in terms of both scale and the nature of the building models) we describe how our system interfaces with IFC, and we conduct timing experiments to determine the practicality of our approach. We discuss general computational approaches for deriving higher-level spatial modalities by focusing on the example of route graphs. Finally, we present a firefighting scenario with alternative route graphs to motivate the application of our framework.

  9. Memória visuo-espacial a curto prazo: os efeitos da supressão articulatória e de uma tarefa aritmética Short-term visuo-spatial memory: the effect of the articulatory suppression and an arithmetic task

    Directory of Open Access Journals (Sweden)

    Cesar Galera

    2003-01-01

    Full Text Available Foram realizados dois experimentos para avaliar a natureza da informação armazenada pelo sistema de memória visuo-espacial a curto prazo. No primeiro experimento, uma tarefa de localização espacial foi realizada simultaneamente com tarefas intervenientes de supressão articulatória e de subtração aritmética. A tarefa de supressão articulatória afeta de forma negativa a recordação das letras, mas não a dos padrões visuais. Apesar disso, a recordação das letras se mantém superior à recordação dos padrões visuais. Este resultado sugere que o armazenamento dos padrões visuais não utiliza o laço fonológico, e que a tarefa de supressão articulatória, embora iniba o uso do laço fonológico, pode não inibir o acesso à informação semântica. No segundo experimento estabelecemos o efeito da similaridade visual sobre a capacidade de recordação da posição espacial. Os resultados confirmam o uso de códigos visuais e sugerem que a capacidade de armazenamento de estímulos visuais é limitada, mas não se restringe ao efeito de recência.We investigated the nature of the information stored in visuo-spatial short-term memory in two experiments. In the first experiment, a spatial localization task was performed simultaneously with articulatory suppression and arithmetical subtraction tasks. The articulatory suppression has a negative effect on the performance with letters, but not with visual patterns. Despite that, the recall of the letters is better than the recall of the visual patterns. This result suggests that the storage of the visual patterns does not use the phonological loop, and that the articulatory suppression, even if it inhibits the use of the phonological loop, cannot inhibit the access to the semantic information. In the second experiment we established the effect of the visual similarity on the capacity of memory for the spatial position. The results confirm the use of visual codes and suggest that the

  10. Project Tasks in Robotics

    DEFF Research Database (Denmark)

    Sørensen, Torben; Hansen, Poul Erik

    1998-01-01

    Description of the compulsary project tasks to be carried out as a part of DTU course 72238 Robotics......Description of the compulsary project tasks to be carried out as a part of DTU course 72238 Robotics...

  11. Spatial networks

    Science.gov (United States)

    Barthélemy, Marc

    2011-02-01

    Complex systems are very often organized under the form of networks where nodes and edges are embedded in space. Transportation and mobility networks, Internet, mobile phone networks, power grids, social and contact networks, and neural networks, are all examples where space is relevant and where topology alone does not contain all the information. Characterizing and understanding the structure and the evolution of spatial networks is thus crucial for many different fields, ranging from urbanism to epidemiology. An important consequence of space on networks is that there is a cost associated with the length of edges which in turn has dramatic effects on the topological structure of these networks. We will thoroughly explain the current state of our understanding of how the spatial constraints affect the structure and properties of these networks. We will review the most recent empirical observations and the most important models of spatial networks. We will also discuss various processes which take place on these spatial networks, such as phase transitions, random walks, synchronization, navigation, resilience, and disease spread.

  12. Spatial interpolation

    NARCIS (Netherlands)

    Stein, A.

    1991-01-01

    The theory and practical application of techniques of statistical interpolation are studied in this thesis, and new developments in multivariate spatial interpolation and the design of sampling plans are discussed. Several applications to studies in soil science are

  13. Spatial Inference Based on Geometric Proportional Analogies

    OpenAIRE

    Mullally, Emma-Claire; O'Donoghue, Diarmuid P.

    2006-01-01

    We describe an instance-based reasoning solution to a variety of spatial reasoning problems. The solution centers on identifying an isomorphic mapping between labelled graphs that represent some problem data and a known solution instance. We describe a number of spatial reasoning problems that are solved by generating non-deductive inferences, integrating topology with area (and other) features. We report the accuracy of our algorithm on different categories of spatial reasoning tasks from th...

  14. Task assignment and coaching

    OpenAIRE

    Dominguez-Martinez, S.

    2009-01-01

    An important task of a manager is to motivate her subordinates. One way in which a manager can give incentives to junior employees is through the assignment of tasks. How a manager allocates tasks in an organization, provides information to the junior employees about his ability. Without coaching from a manager, the junior employee only has information about his past performance. Based on his past performance, a talented junior who has performed a difficult task sometimes decides to leave the...

  15. Functional Task Test (FTT)

    Science.gov (United States)

    Bloomberg, Jacob J.; Mulavara, Ajitkumar; Peters, Brian T.; Rescheke, Millard F.; Wood, Scott; Lawrence, Emily; Koffman, Igor; Ploutz-Snyder, Lori; Spiering, Barry A.; Feeback, Daniel L.; hide

    2009-01-01

    This slide presentation reviews the Functional Task Test (FTT), an interdisciplinary testing regimen that has been developed to evaluate astronaut postflight functional performance and related physiological changes. The objectives of the project are: (1) to develop a set of functional tasks that represent critical mission tasks for the Constellation Program, (2) determine the ability to perform these tasks after space flight, (3) Identify the key physiological factors that contribute to functional decrements and (4) Use this information to develop targeted countermeasures.

  16. Single-Task and Dual-Task Gait Among Collegiate Athletes of Different Sport Classifications: Implications for Concussion Management.

    Science.gov (United States)

    Howell, David R; Oldham, Jessie R; DiFabio, Melissa; Vallabhajosula, Srikant; Hall, Eric E; Ketcham, Caroline J; Meehan, William P; Buckley, Thomas A

    2017-02-01

    Gait impairments have been documented following sport-related concussion. Whether preexisting gait pattern differences exist among athletes who participate in different sport classifications, however, remains unclear. Dual-task gait examinations probe the simultaneous performance of everyday tasks (ie, walking and thinking), and can quantify gait performance using inertial sensors. The purpose of this study was to compare the single-task and dual-task gait performance of collision/contact and noncontact athletes. A group of collegiate athletes (n = 265) were tested before their season at 3 institutions (mean age= 19.1 ± 1.1 years). All participants stood still (single-task standing) and walked while simultaneously completing a cognitive test (dual-task gait), and completed walking trials without the cognitive test (single-task gait). Spatial-temporal gait parameters were compared between collision/contact and noncontact athletes using MANCOVAs; cognitive task performance was compared using ANCOVAs. No significant single-task or dual-task gait differences were found between collision/contact and noncontact athletes. Noncontact athletes demonstrated higher cognitive task accuracy during single-task standing (P = .001) and dual-task gait conditions (P = .02) than collision/contact athletes. These data demonstrate the utility of a dual-task gait assessment outside of a laboratory and suggest that preinjury cognitive task performance during dual-tasks may differ between athletes of different sport classifications.

  17. Task assignment and coaching

    NARCIS (Netherlands)

    Dominguez-Martinez, S.

    2009-01-01

    An important task of a manager is to motivate her subordinates. One way in which a manager can give incentives to junior employees is through the assignment of tasks. How a manager allocates tasks in an organization, provides information to the junior employees about his ability. Without coaching

  18. Differential Age Effects on Spatial and Visual Working Memory

    Science.gov (United States)

    Oosterman, Joukje M.; Morel, Sascha; Meijer, Lisette; Buvens, Cleo; Kessels, Roy P. C.; Postma, Albert

    2011-01-01

    The present study was intended to compare age effects on visual and spatial working memory by using two versions of the same task that differed only in presentation mode. The working memory task contained both a simultaneous and a sequential presentation mode condition, reflecting, respectively, visual and spatial working memory processes. Young…

  19. Modeling object pursuit for 3D interactive tasks in virtual reality

    NARCIS (Netherlands)

    Liu, L.; Liere, van R.

    2011-01-01

    Models of interaction tasks are quantitative descriptions of relationships between human temporal performance and the spatial characteristics of the interactive tasks. Examples include Fitts' law for modeling the pointing task and Accot and Zhai's steering law for the path steering task, etc. Models

  20. Thermodynamic Model of Spatial Memory

    Science.gov (United States)

    Kaufman, Miron; Allen, P.

    1998-03-01

    We develop and test a thermodynamic model of spatial memory. Our model is an application of statistical thermodynamics to cognitive science. It is related to applications of the statistical mechanics framework in parallel distributed processes research. Our macroscopic model allows us to evaluate an entropy associated with spatial memory tasks. We find that older adults exhibit higher levels of entropy than younger adults. Thurstone's Law of Categorical Judgment, according to which the discriminal processes along the psychological continuum produced by presentations of a single stimulus are normally distributed, is explained by using a Hooke spring model of spatial memory. We have also analyzed a nonlinear modification of the ideal spring model of spatial memory. This work is supported by NIH/NIA grant AG09282-06.

  1. Musical expertise has minimal impact on dual task performance.

    Science.gov (United States)

    Cocchini, Gianna; Filardi, Maria Serena; Crhonkova, Marcela; Halpern, Andrea R

    2017-05-01

    Studies investigating effect of practice on dual task performance have yielded conflicting findings, thus supporting different theoretical accounts about the organisation of attentional resources when tasks are performed simultaneously. Because practice has been proven to reduce the demand of attention for the trained task, the impact of long-lasting training on one task is an ideal way to better understand the mechanisms underlying dual task decline in performance. Our study compared performance during dual task execution in expert musicians compared to controls with little if any musical experience. Participants performed a music recognition task and a visuo-spatial task separately (single task) or simultaneously (dual task). Both groups showed a significant but similar performance decline during dual tasks. In addition, the two groups showed a similar decline of dual task performance during encoding and retrieval of the musical information, mainly attributed to a decline in sensitivity. Our results suggest that attention during dual tasks is similarly distributed by expert and non-experts. These findings are in line with previous studies showing a lack of sensitivity to difficulty and lack of practice effect during dual tasks, supporting the idea that different tasks may rely on different and not-sharable attentional resources.

  2. Asymmetric Spatial Processing Under Cognitive Load.

    Science.gov (United States)

    Naert, Lien; Bonato, Mario; Fias, Wim

    2018-01-01

    Spatial attention allows us to selectively process information within a certain location in space. Despite the vast literature on spatial attention, the effect of cognitive load on spatial processing is still not fully understood. In this study we added cognitive load to a spatial processing task, so as to see whether it would differentially impact upon the processing of visual information in the left versus the right hemispace. The main paradigm consisted of a detection task that was performed during the maintenance interval of a verbal working memory task. We found that increasing cognitive working memory load had a more negative impact on detecting targets presented on the left side compared to those on the right side. The strength of the load effect correlated with the strength of the interaction on an individual level. The implications of an asymmetric attentional bias with a relative disadvantage for the left (vs the right) hemispace under high verbal working memory (WM) load are discussed.

  3. Spatial distribution

    DEFF Research Database (Denmark)

    Borregaard, Michael Krabbe; Hendrichsen, Ditte Katrine; Nachman, Gøsta Støger

    2008-01-01

    , depending on the nature of intraspecific interactions between them: while the individuals of some species repel each other and partition the available area, others form groups of varying size, determined by the fitness of each group member. The spatial distribution pattern of individuals again strongly......Living organisms are distributed over the entire surface of the planet. The distribution of the individuals of each species is not random; on the contrary, they are strongly dependent on the biology and ecology of the species, and vary over different spatial scale. The structure of whole...... populations reflects the location and fragmentation pattern of the habitat types preferred by the species, and the complex dynamics of migration, colonization, and population growth taking place over the landscape. Within these, individuals are distributed among each other in regular or clumped patterns...

  4. Spatial Culture

    DEFF Research Database (Denmark)

    Reeh, Henrik

    2012-01-01

    Spatial Culture – A Humanities Perspective Abstract of introductory essay by Henrik Reeh Secured by alliances between socio-political development and cultural practices, a new field of humanistic studies in spatial culture has developed since the 1990s. To focus on links between urban culture...... and modern society is, however, an intellectual practice which has a much longer history. Already in the 1980s, the debate on the modern and the postmodern cited Paris and Los Angeles as spatio-cultural illustrations of these major philosophical concepts. Earlier, in the history of critical studies, the work...... Foucault considered a constitutive feature of 20th-century thinking and one that continues to occupy intellectual and cultural debates in the third millennium. A conceptual framework is, nevertheless, necessary, if the humanities are to adequa-tely address city and space – themes that have long been...

  5. Gaze behaviour during space perception and spatial decision making.

    Science.gov (United States)

    Wiener, Jan M; Hölscher, Christoph; Büchner, Simon; Konieczny, Lars

    2012-11-01

    A series of four experiments investigating gaze behavior and decision making in the context of wayfinding is reported. Participants were presented with screenshots of choice points taken in large virtual environments. Each screenshot depicted alternative path options. In Experiment 1, participants had to decide between them to find an object hidden in the environment. In Experiment 2, participants were first informed about which path option to take as if following a guided route. Subsequently, they were presented with the same images in random order and had to indicate which path option they chose during initial exposure. In Experiment 1, we demonstrate (1) that participants have a tendency to choose the path option that featured the longer line of sight, and (2) a robust gaze bias towards the eventually chosen path option. In Experiment 2, systematic differences in gaze behavior towards the alternative path options between encoding and decoding were observed. Based on data from Experiments 1 and 2 and two control experiments ensuring that fixation patterns were specific to the spatial tasks, we develop a tentative model of gaze behavior during wayfinding decision making suggesting that particular attention was paid to image areas depicting changes in the local geometry of the environments such as corners, openings, and occlusions. Together, the results suggest that gaze during a wayfinding tasks is directed toward, and can be predicted by, a subset of environmental features and that gaze bias effects are a general phenomenon of visual decision making.

  6. Effects of social instability stress in adolescence on long-term, not short-term, spatial memory performance.

    Science.gov (United States)

    Green, Matthew R; McCormick, Cheryl M

    2013-11-01

    There is evidence that exposure to stressors in adolescence leads to lasting deficits on hippocampal-dependent tasks, but whether medial prefrontal cortical function is also impaired is unknown. We previously found that rats exposed to social instability stress in adolescence (SS; daily 1h isolation and subsequent change of cage partner between postnatal days 30 and 45) had impaired memory performance on a Spatial Object Location test and in memory for fear conditioning context, tasks that depend on the integrity of the hippocampus. Here we investigated whether impaired performance would be evident after adolescent SS in male rats on a different test of hippocampal function, spatial learning and memory in the Morris water maze (MWM) and on a working memory task for which performance depends on the integrity of the medial prefrontal cortex, the Delayed Alternation task (DAT). During MWM testing, SS rats showed greater improvements in performance across trials within days compared to control (CTL) rats, but showed less retention of learning between days (48 h) compared to CTL rats. Similarly, SS rats had impaired long-term memory in the Spatial Object Location test after a long delay (240 min), but not after shorter delays (15 or 60 min) compared to CTL rats. No group differences were observed on the DAT, which assessed working memory across brief delays (5-90 s). Thus, deficits in memory performance after chronic social stress in adolescence may be limited to long-term memory. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Contextual control over task-set retrieval.

    Science.gov (United States)

    Crump, Matthew J C; Logan, Gordon D

    2010-11-01

    Contextual cues signaling task likelihood or the likelihood of task repetition are known to modulate the size of switch costs. We follow up on the finding by Leboe, Wong, Crump, and Stobbe (2008) that location cues predictive of the proportion of switch or repeat trials modulate switch costs. Their design employed one cue per task, whereas our experiment employed two cues per task, which allowed separate assessment of modulations to the cue-repetition benefit, a measure of lower level cue-encoding processes, and to the task-alternation cost, a measure of higher level processes representing task-set information. We demonstrate that location information predictive of switch proportion modulates performance at the level of task-set representations. Furthermore, we demonstrate that contextual control occurs even when subjects are unaware of the associations between context and switch likelihood. We discuss the notion that contextual information provides rapid, unconscious control over the extent to which prior task-set representations are retrieved in the service of guiding online performance.

  8. An alternative dimensional reduction prescription

    International Nuclear Information System (INIS)

    Edelstein, J.D.; Giambiagi, J.J.; Nunez, C.; Schaposnik, F.A.

    1995-08-01

    We propose an alternative dimensional reduction prescription which in respect with Green functions corresponds to drop the extra spatial coordinate. From this, we construct the dimensionally reduced Lagrangians both for scalars and fermions, discussing bosonization and supersymmetry in the particular 2-dimensional case. We argue that our proposal is in some situations more physical in the sense that it maintains the form of the interactions between particles thus preserving the dynamics corresponding to the higher dimensional space. (author). 12 refs

  9. The Creative task Creator: a tool for the generation of customized, Web-based creativity tasks.

    Science.gov (United States)

    Pretz, Jean E; Link, John A

    2008-11-01

    This article presents a Web-based tool for the creation of divergent-thinking and open-ended creativity tasks. A Java program generates HTML forms with PHP scripting that run an Alternate Uses Task and/or open-ended response items. Researchers may specify their own instructions, objects, and time limits, or use default settings. Participants can also be prompted to select their best responses to the Alternate Uses Task (Silvia et al., 2008). Minimal programming knowledge is required. The program runs on any server, and responses are recorded in a standard MySQL database. Responses can be scored using the consensual assessment technique (Amabile, 1996) or Torrance's (1998) traditional scoring method. Adoption of this Web-based tool should facilitate creativity research across cultures and access to eminent creators. The Creative Task Creator may be downloaded from the Psychonomic Society's Archive of Norms, Stimuli, and Data, www.psychonomic.org/archive.

  10. Preparatory neural activity predicts performance on a conflict task.

    Science.gov (United States)

    Stern, Emily R; Wager, Tor D; Egner, Tobias; Hirsch, Joy; Mangels, Jennifer A

    2007-10-24

    Advance preparation has been shown to improve the efficiency of conflict resolution. Yet, with little empirical work directly linking preparatory neural activity to the performance benefits of advance cueing, it is not clear whether this relationship results from preparatory activation of task-specific networks, or from activity associated with general alerting processes. Here, fMRI data were acquired during a spatial Stroop task in which advance cues either informed subjects of the upcoming relevant feature of conflict stimuli (spatial or semantic) or were neutral. Informative cues decreased reaction time (RT) relative to neutral cues, and cues indicating that spatial information would be task-relevant elicited greater activity than neutral cues in multiple areas, including right anterior prefrontal and bilateral parietal cortex. Additionally, preparatory activation in bilateral parietal cortex and right dorsolateral prefrontal cortex predicted faster RT when subjects responded to spatial location. No regions were found to be specific to semantic cues at conventional thresholds, and lowering the threshold further revealed little overlap between activity associated with spatial and semantic cueing effects, thereby demonstrating a single dissociation between activations related to preparing a spatial versus semantic task-set. This relationship between preparatory activation of spatial processing networks and efficient conflict resolution suggests that advance information can benefit performance by leading to domain-specific biasing of task-relevant information.

  11. Spatial Mismatch: A Third Generation Survey.

    Science.gov (United States)

    Eagan, J. Vincent

    1999-01-01

    The spatial mismatch argument hypothesizes that racial discrimination in the housing market, together with the suburbanization of low skilled jobs, contributes significantly to the high unemployment and/or low wages of inner city minority workers. Surveys recent spatial mismatch literature and discusses policy alternatives, focusing on areas…

  12. Strategic Adaptation to Task Characteristics, Incentives, and Individual Differences in Dual-Tasking.

    Directory of Open Access Journals (Sweden)

    Christian P Janssen

    Full Text Available We investigate how good people are at multitasking by comparing behavior to a prediction of the optimal strategy for dividing attention between two concurrent tasks. In our experiment, 24 participants had to interleave entering digits on a keyboard with controlling a randomly moving cursor with a joystick. The difficulty of the tracking task was systematically varied as a within-subjects factor. Participants were also exposed to different explicit reward functions that varied the relative importance of the tracking task relative to the typing task (between-subjects. Results demonstrate that these changes in task characteristics and monetary incentives, together with individual differences in typing ability, influenced how participants choose to interleave tasks. This change in strategy then affected their performance on each task. A computational cognitive model was used to predict performance for a wide set of alternative strategies for how participants might have possibly interleaved tasks. This allowed for predictions of optimal performance to be derived, given the constraints placed on performance by the task and cognition. A comparison of human behavior with the predicted optimal strategy shows that participants behaved near optimally. Our findings have implications for the design and evaluation of technology for multitasking situations, as consideration should be given to the characteristics of the task, but also to how different users might use technology depending on their individual characteristics and their priorities.

  13. Movement Induces the Use of External Spatial Coordinates for Tactile Localization in Congenitally Blind Humans.

    Science.gov (United States)

    Heed, Tobias; Möller, Johanna; Röder, Brigitte

    2015-01-01

    To localize touch, the brain integrates spatial information coded in anatomically based and external spatial reference frames. Sighted humans, by default, use both reference frames in tactile localization. In contrast, congenitally blind individuals have been reported to rely exclusively on anatomical coordinates, suggesting a crucial role of the visual system for tactile spatial processing. We tested whether the use of external spatial information in touch can, alternatively, be induced by a movement context. Sighted and congenitally blind humans performed a tactile temporal order judgment task that indexes the use of external coordinates for tactile localization, while they executed bimanual arm movements with uncrossed and crossed start and end postures. In the sighted, start posture and planned end posture of the arm movement modulated tactile localization for stimuli presented before and during movement, indicating automatic, external recoding of touch. Contrary to previous findings, tactile localization of congenitally blind participants, too, was affected by external coordinates, though only for stimuli presented before movement start. Furthermore, only the movement's start posture, but not the planned end posture affected blind individuals' tactile performance. Thus, integration of external coordinates in touch is established without vision, though more selectively than when vision has developed normally, and possibly restricted to movement contexts. The lack of modulation by the planned posture in congenitally blind participants suggests that external coordinates in this group are not mediated by motor efference copy. Instead the task-related frequent posture changes, that is, movement consequences rather than planning, appear to have induced their use of external coordinates.

  14. Overview of the ID, EPI and REL tasks of BioNLP Shared Task 2011

    Directory of Open Access Journals (Sweden)

    Pyysalo Sampo

    2012-06-01

    of performance sufficient for user-facing applications. In this study, we extend on previously reported results and perform further analyses of the outputs of the participating systems. We place specific emphasis on aspects of system performance relating to real-world applicability, considering alternate evaluation metrics and performing additional manual analysis of system outputs. We further demonstrate that the strengths of extraction systems can be combined to improve on the performance achieved by any system in isolation. The manually annotated corpora, supporting resources, and evaluation tools for all tasks are available from http://www.bionlp-st.org and the tasks continue as open challenges for all interested parties.

  15. Haptic spatial matching in near peripersonal space.

    Science.gov (United States)

    Kaas, Amanda L; Mier, Hanneke I van

    2006-04-01

    Research has shown that haptic spatial matching at intermanual distances over 60 cm is prone to large systematic errors. The error pattern has been explained by the use of reference frames intermediate between egocentric and allocentric coding. This study investigated haptic performance in near peripersonal space, i.e. at intermanual distances of 60 cm and less. Twelve blindfolded participants (six males and six females) were presented with two turn bars at equal distances from the midsagittal plane, 30 or 60 cm apart. Different orientations (vertical/horizontal or oblique) of the left bar had to be matched by adjusting the right bar to either a mirror symmetric (/ \\) or parallel (/ /) position. The mirror symmetry task can in principle be performed accurately in both an egocentric and an allocentric reference frame, whereas the parallel task requires an allocentric representation. Results showed that parallel matching induced large systematic errors which increased with distance. Overall error was significantly smaller in the mirror task. The task difference also held for the vertical orientation at 60 cm distance, even though this orientation required the same response in both tasks, showing a marked effect of task instruction. In addition, men outperformed women on the parallel task. Finally, contrary to our expectations, systematic errors were found in the mirror task, predominantly at 30 cm distance. Based on these findings, we suggest that haptic performance in near peripersonal space might be dominated by different mechanisms than those which come into play at distances over 60 cm. Moreover, our results indicate that both inter-individual differences and task demands affect task performance in haptic spatial matching. Therefore, we conclude that the study of haptic spatial matching in near peripersonal space might reveal important additional constraints for the specification of adequate models of haptic spatial performance.

  16. Engineering Task Plan for simulated riser installation by use of rotary drilling

    International Nuclear Information System (INIS)

    Barnes, G.A.

    1995-12-01

    This task is being performed to demonstrate the feasibility of the best riser installation alternative identified in the Engineering Study. This Engineering Task Plan (ETP) will be the WHC project management plan for the riser installation demonstration activities

  17. A quantitative method for determining spatial discriminative capacity

    Directory of Open Access Journals (Sweden)

    Dennis Robert G

    2008-03-01

    Full Text Available Abstract Background The traditional two-point discrimination (TPD test, a widely used tactile spatial acuity measure, has been criticized as being imprecise because it is based on subjective criteria and involves a number of non-spatial cues. The results of a recent study showed that as two stimuli were delivered simultaneously, vibrotactile amplitude discrimination became worse when the two stimuli were positioned relatively close together and was significantly degraded when the probes were within a subject's two-point limen. The impairment of amplitude discrimination with decreasing inter-probe distance suggested that the metric of amplitude discrimination could possibly provide a means of objective and quantitative measurement of spatial discrimination capacity. Methods A two alternative forced-choice (2AFC tracking procedure was used to assess a subject's ability to discriminate the amplitude difference between two stimuli positioned at near-adjacent skin sites. Two 25 Hz flutter stimuli, identical except for a constant difference in amplitude, were delivered simultaneously to the hand dorsum. The stimuli were initially spaced 30 mm apart, and the inter-stimulus distance was modified on a trial-by-trial basis based on the subject's performance of discriminating the stimulus with higher intensity. The experiment was repeated via sequential, rather than simultaneous, delivery of the same vibrotactile stimuli. Results Results obtained from this study showed that the performance of the amplitude discrimination task was significantly degraded when the stimuli were delivered simultaneously and were near a subject's two-point limen. In contrast, subjects were able to correctly discriminate between the amplitudes of the two stimuli when they were sequentially delivered at all inter-probe distances (including those within the two-point limen, and improved when an adapting stimulus was delivered prior to simultaneously delivered stimuli. Conclusion

  18. Transport Task Force Leadership, Task 4

    International Nuclear Information System (INIS)

    Callen, J.D.

    1991-07-01

    The Transport Task Force (TTF) was initiated as a broad-based US magnetic fusion community activity during the fall of 1988 to focus attention on and encourage development of an increased understanding of anomalous transport in tokamaks. The overall TTF goal is to make progress on Characterizing, Understanding and Identifying how to Reduce plasma transport in tokamaks -- to CUIR transport

  19. Sex effects on spatial learning but not on spatial memory retrieval in healthy young adults.

    Science.gov (United States)

    Piber, Dominique; Nowacki, Jan; Mueller, Sven C; Wingenfeld, Katja; Otte, Christian

    2018-01-15

    Sex differences have been found in spatial learning and spatial memory, with several studies indicating that males outperform females. We tested in the virtual Morris Water Maze (vMWM) task, whether sex differences in spatial cognitive processes are attributable to differences in spatial learning or spatial memory retrieval in a large student sample. We tested 90 healthy students (45 women and 45 men) with a mean age of 23.5 years (SD=3.5). Spatial learning and spatial memory retrieval were measured by using the vMWM task, during which participants had to search a virtual pool for a hidden platform, facilitated by visual cues surrounding the pool. Several learning trials assessed spatial learning, while a separate probe trial assessed spatial memory retrieval. We found a significant sex effect during spatial learning, with males showing shorter latency and shorter path length, as compared to females (all pretrieval (p=0.615). Furthermore, post-hoc analyses revealed significant sex differences in spatial search strategies (pretrieval. Our study raises the question, whether men and women use different learning strategies, which nevertheless result in equal performances of spatial memory retrieval. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. "Photographing money" task pricing

    Science.gov (United States)

    Jia, Zhongxiang

    2018-05-01

    "Photographing money" [1]is a self-service model under the mobile Internet. The task pricing is reasonable, related to the success of the commodity inspection. First of all, we analyzed the position of the mission and the membership, and introduced the factor of membership density, considering the influence of the number of members around the mission on the pricing. Multivariate regression of task location and membership density using MATLAB to establish the mathematical model of task pricing. At the same time, we can see from the life experience that membership reputation and the intensity of the task will also affect the pricing, and the data of the task success point is more reliable. Therefore, the successful point of the task is selected, and its reputation, task density, membership density and Multiple regression of task positions, according to which a nhew task pricing program. Finally, an objective evaluation is given of the advantages and disadvantages of the established model and solution method, and the improved method is pointed out.

  1. Board Task Performance

    DEFF Research Database (Denmark)

    Minichilli, Alessandro; Zattoni, Alessandro; Nielsen, Sabina

    2012-01-01

    identify three board processes as micro-level determinants of board effectiveness. Specifically, we focus on effort norms, cognitive conflicts and the use of knowledge and skills as determinants of board control and advisory task performance. Further, we consider how two different institutional settings....... The findings show that: (i) Board processes have a larger potential than demographic variables to explain board task performance; (ii) board task performance differs significantly between boards operating in different contexts; and (iii) national context moderates the relationships between board processes...... and board task performance....

  2. Spatial information is preferentially processed by the distal part of CA3: implication for memory retrieval.

    Science.gov (United States)

    Flasbeck, Vera; Atucha, Erika; Nakamura, Nozomu H; Yoshida, Motoharu; Sauvage, Magdalena M

    2018-07-16

    For the past decades, CA3 was considered as a single functional entity. However, strong differences between the proximal (close to the dentate gyrus) and the distal (close to CA2) parts of CA3 in terms of connectivity patterns, gene expression and electrophysiological properties suggest that it is not the case. We recently showed that proximal CA3 (together with distal CA1) preferentially deals with non-spatial information [1]. In contrast to proximal CA3, distal CA3 mainly receives and predominantly projects to spatially tuned areas. Here, we tested if distal CA3 preferentially processes spatial information, which would suggest a segregation of the spatial information along the proximodistal axis of CA3. We used a high-resolution imaging technique based on the detection of the expression of the immediate-early gene Arc, commonly used to map activity in the medial temporal lobe. We showed that distal CA3 is strongly recruited in a newly designed delayed nonmatching-to-location task with high memory demands in rats, while proximal CA3 is not. These results indicate a functional segregation of CA3 that mirrors the one reported in CA1, and suggest the existence of a distal CA3- proximal CA1 spatial subnetwork. These findings bring further evidence for the existence of 'specialized' spatial and non-spatial subnetworks segregated along the proximodistal axis of the hippocampus and put forward the 'segregated' view of information processing in the hippocampus as a reasonable alternative to the well-accepted 'integrated' view, according to which spatial and non-spatial information are systematically integrated in the hippocampus to form episodic memory. Copyright © 2018. Published by Elsevier B.V.

  3. Spatial-Sequential and Spatial-Simultaneous Working Memory in Individuals with Williams Syndrome

    Science.gov (United States)

    Lanfranchi, Silvia; De Mori, Letizia; Mammarella, Irene C.; Carretti, Barbara; Vianello, Renzo

    2015-01-01

    The aim of the present study was to compare visuospatial working memory performance in 18 individuals with Williams syndrome (WS) and 18 typically developing (TD) children matched for nonverbal mental age. Two aspects were considered: task presentation format (i.e., spatial-sequential or spatial-simultaneous), and level of attentional control…

  4. Spatial Language Facilitates Spatial Cognition: Evidence from Children Who Lack Language Input

    Science.gov (United States)

    Gentner, Dedre; Ozyurek, Asli; Gurcanli, Ozge; Goldin-Meadow, Susan

    2013-01-01

    Does spatial language influence how people think about space? To address this question, we observed children who did not know a conventional language, and tested their performance on nonlinguistic spatial tasks. We studied deaf children living in Istanbul whose hearing losses prevented them from acquiring speech and whose hearing parents had not…

  5. Sexual orientation and spatial memory.

    Science.gov (United States)

    Cánovas, Ma Rosa; Cimadevilla, José Manuel

    2011-11-01

    The present study aimed at determining the influence of sexual orientation in human spatial learning and memory. Participants performed the Boxes Room, a virtual reality version of the Holeboard. In Experiment I, a reference memory task, the position of the hidden rewards remained constant during the whole experiment. In Experiment II, a working memory task, the position of rewards changed between blocks. Each block consisted of two trials: One trial for acquisition and another for retrieval. The results of Experiment I showed that heterosexual men performed better than homosexual men and heterosexual women. They found the rewarded boxes faster. Moreover, homosexual participants committed more errors than heterosexuals. Experiment II showed that working memory abilities are the same in groups of different sexual orientation. These results suggest that sexual orientation is related to spatial navigation abilities, but mostly in men, and limited to reference memory, which depends more on the function of the hippocampal system.

  6. Teachers' Spatial Literacy as Visualization, Reasoning, and Communication

    Science.gov (United States)

    Moore-Russo, Deborah; Viglietti, Janine M.; Chiu, Ming Ming; Bateman, Susan M.

    2013-01-01

    This paper conceptualizes spatial literacy as consisting of three overlapping domains: visualization, reasoning, and communication. By considering these domains, this study explores different aspects of spatial literacy to better understand how a group of mathematics teachers reasoned about spatial tasks. Seventy-five preservice and inservice…

  7. Spatial Attention and Audiovisual Interactions in Apparent Motion

    Science.gov (United States)

    Sanabria, Daniel; Soto-Faraco, Salvador; Spence, Charles

    2007-01-01

    In this study, the authors combined the cross-modal dynamic capture task (involving the horizontal apparent movement of visual and auditory stimuli) with spatial cuing in the vertical dimension to investigate the role of spatial attention in cross-modal interactions during motion perception. Spatial attention was manipulated endogenously, either…

  8. Task analysis methods applicable to control room design review (CDR)

    International Nuclear Information System (INIS)

    Moray, N.P.; Senders, J.W.; Rhodes, W.

    1985-06-01

    This report presents the results of a research study conducted in support of the human factors engineering program of the Atomic Energy Control Board in Canada. It contains five products which may be used by the Atomic Enegy Control Board in relation to Task Analysis of jobs in CANDU nuclear power plants: 1. a detailed method for preparing for a task analysis; 2. a Task Data Form for recording task analysis data; 3. a detailed method for carrying out task analyses; 4. a guide to assessing alternative methods for performing task analyses, if such are proposed by utilities or consultants; and 5. an annotated bibliography on task analysis. In addition, a short explanation of the origins, nature and uses of task analysis is provided, with some examples of its cost effectiveness. 35 refs

  9. Spatial filtring and thermocouple spatial filter

    International Nuclear Information System (INIS)

    Han Bing; Tong Yunxian

    1989-12-01

    The design and study on thermocouple spatial filter have been conducted for the flow measurement of integrated reactor coolant. The fundamental principle of spatial filtring, mathematical descriptions and analyses of thermocouple spatial filter are given

  10. Explicit goal-driven attention, unlike implicitly learned attention, spreads to secondary tasks.

    Science.gov (United States)

    Addleman, Douglas A; Tao, Jinyi; Remington, Roger W; Jiang, Yuhong V

    2018-03-01

    To what degree does spatial attention for one task spread to all stimuli in the attended region, regardless of task relevance? Most models imply that spatial attention acts through a unitary priority map in a task-general manner. We show that implicit learning, unlike endogenous spatial cuing, can bias spatial attention within one task without biasing attention to a spatially overlapping secondary task. Participants completed a visual search task superimposed on a background containing scenes, which they were told to encode for a later memory task. Experiments 1 and 2 used explicit instructions to bias spatial attention to one region for visual search; Experiment 3 used location probability cuing to implicitly bias spatial attention. In location probability cuing, a target appeared in one region more than others despite participants not being told of this. In all experiments, search performance was better in the cued region than in uncued regions. However, scene memory was better in the cued region only following endogenous guidance, not after implicit biasing of attention. These data support a dual-system view of top-down attention that dissociates goal-driven and implicitly learned attention. Goal-driven attention is task general, amplifying processing of a cued region across tasks, whereas implicit statistical learning is task-specific. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  11. Increased cognitive control after task conflict? Investigating the N-3 effect in task switching.

    Science.gov (United States)

    Schuch, Stefanie; Grange, James A

    2018-05-25

    Task inhibition is considered to facilitate switching to a new task and is assumed to decay slowly over time. Hence, more persisting inhibition needs to be overcome when returning to a task after one intermediary trial (ABA task sequence) than when returning after two or more intermediary trials (CBA task sequence). Schuch and Grange (J Exp Psychol Learn Mem Cogn 41:760-767, 2015) put forward the hypothesis that there is higher task conflict in ABA than CBA sequences, leading to increased cognitive control in the subsequent trial. They provided evidence that performance is better in trials following ABA than following CBA task sequences. Here, this effect of the previous task sequence ("N-3 effect") is further investigated by varying the cue-stimulus interval (CSI), allowing for short (100 ms) or long (900 ms) preparation time for the upcoming task. If increased cognitive control after ABA involves a better preparation for the upcoming task, the N-3 effect should be larger with long than short CSI. The results clearly show that this is not the case. In Experiment 1, the N-3 effect was smaller with long than short CSI; in Experiment 2, the N-3 effect was not affected by CSI. Diffusion model analysis confirmed previous results in the literature (regarding the effect of CSI and of the ABA-CBA difference); however, the N-3 effect was not unequivocally associated with any of the diffusion model parameters. In exploratory analysis, we also tested the alternative hypothesis that the N-3 effect involves more effective task shielding, which would be reflected in reduced congruency effects in trials following ABA, relative to trials following CBA; congruency effects did not differ between these conditions. Taken together, we can rule out two potential explanations of the N-3 effect: Neither is this effect due to enhanced task preparation, nor to more effective task shielding.

  12. The Spatial Politics of Spatial Representation

    DEFF Research Database (Denmark)

    Olesen, Kristian; Richardson, Tim

    2011-01-01

    spatial planning in Denmark reveals how fuzzy spatial representations and relational spatial concepts are being used to depoliticise strategic spatial planning processes and to camouflage spatial politics. The paper concludes that, while relational geography might play an important role in building......This paper explores the interplay between the spatial politics of new governance landscapes and innovations in the use of spatial representations in planning. The central premise is that planning experiments with new relational approaches become enmeshed in spatial politics. The case of strategic...

  13. Spatial Processing in Infancy Predicts Both Spatial and Mathematical Aptitude in Childhood.

    Science.gov (United States)

    Lauer, Jillian E; Lourenco, Stella F

    2016-10-01

    Despite considerable interest in the role of spatial intelligence in science, technology, engineering, and mathematics (STEM) achievement, little is known about the ontogenetic origins of individual differences in spatial aptitude or their relation to later accomplishments in STEM disciplines. The current study provides evidence that spatial processes present in infancy predict interindividual variation in both spatial and mathematical competence later in development. Using a longitudinal design, we found that children's performance on a brief visuospatial change-detection task administered between 6 and 13 months of age was related to their spatial aptitude (i.e., mental-transformation skill) and mastery of symbolic-math concepts at 4 years of age, even when we controlled for general cognitive abilities and spatial memory. These results suggest that nascent spatial processes present in the first year of life not only act as precursors to later spatial intelligence but also predict math achievement during childhood.

  14. Supporting complex search tasks

    DEFF Research Database (Denmark)

    Gäde, Maria; Hall, Mark; Huurdeman, Hugo

    2015-01-01

    , is fragmented at best. The workshop addressed the many open research questions: What are the obvious use cases and applications of complex search? What are essential features of work tasks and search tasks to take into account? And how do these evolve over time? With a multitude of information, varying from...

  15. Task leaders reports

    International Nuclear Information System (INIS)

    Loriaux, E.F.; Jehee, J.N.T.

    1995-01-01

    Report on CRP-OSS Task 4.1.1. ''Survey of existing documentation relevant to this programme's goals'' and report on CRP-OSS Task 4.1.2. ''Survey of existing Operator Support Systems and the experience with them'' are presented. 2 tabs

  16. Alternative Fuel Guidelines for Alternative Transportation Systems.

    Science.gov (United States)

    2011-01-31

    The Volpe Center documented the increased use of alternative fuels on vehicles owned and operated by federal land management agencies. For each alternative fuel type, the Volpe Center documented the availability of vehicles, fueling mechanisms and pr...

  17. Spatial Construction Skills of Chimpanzees ("Pan Troglodytes") and Young Human Children ("Homo Sapiens Sapiens")

    Science.gov (United States)

    Poti, Patrizia; Hayashi, Misato; Matsuzawa, Tetsuro

    2009-01-01

    Spatial construction tasks are basic tests of visual-spatial processing. Two studies have assessed spatial construction skills in chimpanzees (Pan troglodytes) and young children (Homo sapiens sapiens) with a block modelling task. Study 1a subjects were three young chimpanzees and five adult chimpanzees. Study 1b subjects were 30 human children…

  18. The effect of task complexity and task conditions on foreign language development and performance: three empirical studies

    NARCIS (Netherlands)

    Sercu, L.; de Wachter, L.; Peters, E.; Kuiken, F.; Vedder, I.

    2006-01-01

    It has been argued that tasks constitute a valid alternative unit to sequence the language learning process, as opposed to linguistically defined syllabuses. Implementing this claim presupposes that it is possible to access the cognitive and linguistic demands of tasks, so that they can be sequenced

  19. Report of the Task Force on Computer Charging.

    Science.gov (United States)

    Computer Co-ordination Group, Ottawa (Ontario).

    The objectives of the Task Force on Computer Charging as approved by the Committee of Presidents of Universities of Ontario were: (1) to identify alternative methods of costing computing services; (2) to identify alternative methods of pricing computing services; (3) to develop guidelines for the pricing of computing services; (4) to identify…

  20. Simulating the Effects of Alternative Forest Management Strategies on Landscape Structure

    Science.gov (United States)

    Eric J. Gustafson; Thomas Crow

    1996-01-01

    Quantitative, spatial tools are needed to assess the long-term spatial consequences of alternative management strategies for land use planning and resource management. We constructed a timber harvest allocation model (HARVEST) that provides a visual and quantitative means to predict the spatial pattern of forest openings produced by alternative harvest strategies....

  1. Observer efficiency in free-localization tasks with correlated noise

    Directory of Open Access Journals (Sweden)

    Craig eAbbey

    2014-05-01

    Full Text Available The efficiency of visual tasks involving localization has traditionally been evaluated using forced choice experiments that capitalize on independence across locations to simplify the performance of the ideal observer. However, developments in ideal observer analysis have shown how an ideal observer can be defined for free-localization tasks, where a target can appear anywhere in a defined search region and subjects respond by localizing the target. Since these tasks are representative of many real-world search tasks, it is of interest to evaluate the efficiency of observer performance in them. The central question of this work is whether humans are able to effectively use the information in a free-localization task relative to a similar task where target location is fixed. We use a yes-no detection task at a cued location as the reference for this comparison. Each of the tasks is evaluated using a Gaussian target profile embedded in four different Gaussian noise backgrounds having power-law noise power spectra with exponents ranging from 0 to 3. The free localization task had a square 6.7° search region. We report on two follow-up studies investigating efficiency in a detect-and-localize task, and the effect of processing the white-noise backgrounds. In the fixed-location detection task, we find average observer efficiency ranges from 35% to 59% for the different noise backgrounds. Observer efficiency improves dramatically in the tasks involving localization, ranging from 63% to 82% in the forced localization tasks and from 78% to 92% in the detect-and- localize tasks. Performance in white noise, the lowest efficiency condition, was improved by filtering to give them a power-law exponent of 2. Classification images, used to examine spatial frequency weights for the tasks, show better tuning to ideal weights in the free-localization tasks. The high absolute levels of efficiency suggest that observers are well-adapted to free-localization tasks.

  2. Presence and the utility of audio spatialization

    DEFF Research Database (Denmark)

    Bormann, Karsten

    2005-01-01

    The primary concern of this paper is whether the utility of audio spatialization, as opposed to the fidelity of audio spatialization, impacts presence. An experiment is reported that investigates the presence-performance relationship by decoupling spatial audio fidelity (realism) from task...... performance by varying the spatial fidelity of the audio independently of its relevance to performance on the search task that subjects were to perform. This was achieved by having conditions in which subjects searched for a music-playing radio (an active sound source) and having conditions in which...... supplied only nonattenuated audio was detrimental to performance. Even so, this group of subjects consistently had the largest increase in presence scores over the baseline experiment. Further, the Witmer and Singer (1998) presence questionnaire was more sensitive to whether the audio source was active...

  3. Generic cognitive adaptations to task interference in task switching

    NARCIS (Netherlands)

    Poljac, E.; Bekkering, H.

    2009-01-01

    The present study investigated how the activation of previous tasks interferes with the execution of future tasks as a result of temporal manipulations. Color and shape matching tasks were organized in runs of two trials each. The tasks were specified by a cue presented before a task run, cueing

  4. Energy Efficient Task Light

    DEFF Research Database (Denmark)

    Logadottir, Asta; Ardkapan, Siamak Rahimi; Johnsen, Kjeld

    2014-01-01

    The objectives of this work is to develop a task light for office lighting that fulfils the minimum requirements of the European standard EN12464 - 1 : Light and lighting – Lighting of work places, Part 1: Indoor workplaces and the Danish standard DS 700 : Lys og belysning I arbejdsrum , or more...... specifically the requirements that apply to the work area and the immediate surrounding area. By providing a task light that fulfils the requirements for task lighting and the immediate surrounding area, the general lighting only needs to provide the illuminance levels required for background lighting...... and thereby a reduction in installed power for general lighting of about 40 % compared to the way illuminance levels are designed in an office environment in Denmark today. This lighting strategy is useful when the placement of the task area is not defined in the space before the lighting is design ed...

  5. Gender differences in multitasking reflect spatial ability.

    Science.gov (United States)

    Mäntylä, Timo

    2013-04-01

    Demands involving the scheduling and interleaving of multiple activities have become increasingly prevalent, especially for women in both their paid and unpaid work hours. Despite the ubiquity of everyday requirements to multitask, individual and gender-related differences in multitasking have gained minimal attention in past research. In two experiments, participants completed a multitasking session with four gender-fair monitoring tasks and separate tasks measuring executive functioning (working memory updating) and spatial ability (mental rotation). In both experiments, males outperformed females in monitoring accuracy. Individual differences in executive functioning and spatial ability were independent predictors of monitoring accuracy, but only spatial ability mediated gender differences in multitasking. Menstrual changes accentuated these effects, such that gender differences in multitasking (and spatial ability) were eliminated between males and females who were in the menstrual phase of the menstrual cycle but not between males and females who were in the luteal phase. These findings suggest that multitasking involves spatiotemporal task coordination and that gender differences in multiple-task performance reflect differences in spatial ability.

  6. Distraction during learning with hypermedia: Difficult tasks help to keep task goals on track

    Directory of Open Access Journals (Sweden)

    Katharina eScheiter

    2014-03-01

    Full Text Available In educational hypermedia environments, students are often confronted with potential sources of distraction arising from additional information that, albeit interesting, is unrelated to their current task goal. The paper investigates the conditions under which distraction occurs and hampers performance. Based on theories of volitional action control it was hypothesized that interesting information, especially if related to a pending goal, would interfere with task performance only when working on easy, but not on difficult tasks. In Experiment 1, 66 students learned about probability theory using worked examples and solved corresponding test problems, whose task difficulty was manipulated. As a second factor, the presence of interesting information unrelated to the primary task was varied. Results showed that students solved more easy than difficult probability problems correctly. However, the presence of interesting, but task-irrelevant information did not interfere with performance. In Experiment 2, 68 students again engaged in example-based learning and problem solving in the presence of task-irrelevant information. Problem-solving difficulty was varied as a first factor. Additionally, the presence of a pending goal related to the task-irrelevant information was manipulated. As expected, problem-solving performance declined when a pending goal was present during working on easy problems, whereas no interference was observed for difficult problems. Moreover, the presence of a pending goal reduced the time on task-relevant information and increased the time on task-irrelevant information while working on easy tasks. However, as revealed by mediation analyses these changes in overt information processing behavior did not explain the decline in problem-solving performance. As an alternative explanation it is suggested that goal conflicts resulting from pending goals claim cognitive resources, which are then no longer available for learning and

  7. Spatial representations are specific to different domains of knowledge.

    Directory of Open Access Journals (Sweden)

    Rowena Beecham

    Full Text Available There is evidence that many abstract concepts are represented cognitively in a spatial format. However, it is unknown whether similar spatial processes are employed in different knowledge domains, or whether individuals exhibit similar spatial profiles within and across domains. This research investigated similarities in spatial representation in two knowledge domains--mathematics and music. Sixty-one adults completed analogous number magnitude and pitch discrimination tasks: the Spatial-Numerical Association of Response Codes and Spatial-Musical Association of Response Codes tasks. Subgroups of individuals with different response patterns were identified through cluster analyses. For both the mathematical and musical tasks, approximately half of the participants showed the expected spatial judgment effect when explicitly cued to focus on the spatial properties of the stimuli. Despite this, performances on the two tasks were largely independent. Consistent with previous research, the study provides evidence for the spatial representation of number and pitch in the majority of individuals. However, there was little evidence to support the claim that the same spatial representation processes underpin mathematical and musical judgments.

  8. Contaminated sediment research task: SHC Task 3.61.3

    Science.gov (United States)

    A poster presentation for the SHC BOSC review will summarize the research efforts under Sustainable and Healthy Communities Research Program (SHC) in the Contaminated Sediment Task within the Contaminated Sites Project. For the Task, Problem Summary & Decision Context; Task O...

  9. Same task, different strategies: How brain networks can be influenced by memory strategy

    OpenAIRE

    Sanfratello, Lori; Caprihan, Arvind; Stephen, Julia M.; Knoefel, Janice E.; Adair, John C.; Qualls, Clifford; Lundy, S. Laura; Aine, Cheryl J.

    2014-01-01

    Previous functional neuroimaging studies demonstrated that different neural networks underlie different types of cognitive processing by engaging participants in particular tasks, such as verbal or spatial working memory (WM) tasks. However, we report here that even when a working memory task is defined as verbal or spatial, different types of memory strategies may be employed to complete it, with concomitant variations in brain activity. We developed a questionnaire to characterize the type ...

  10. Spatial vision in Bombus terrestris

    Directory of Open Access Journals (Sweden)

    Aravin eChakravarthi

    2016-02-01

    Full Text Available Bombus terrestris is one of the most commonly used insect models to investigate visually guided behavior and spatial vision in particular. Two fundamental measures of spatial vision are spatial resolution and contrast sensitivity. In this study, we report the threshold of spatial resolution in B. terrestris and characterize the contrast sensitivity function of the bumblebee visual system for a dual choice discrimination task. We trained bumblebees in a Y-maze experimental set-up to associate a vertical sinusoidal grating with a sucrose reward, and a horizontal grating with absence of a reward. Using a logistic psychometric function, we estimated a resolution threshold of 0.21 cycles deg-1 of visual angle. This resolution is in the same range but slightly lower than that found in honeybees (Apis mellifera and A. cerana and another bumblebee species (B. impatiens. We also found that the contrast sensitivity of B. terrestris was 1.57 for the spatial frequency 0.09 cycles deg-1 and 1.26. for 0.18 cycles deg-1.

  11. Object versus spatial visual mental imagery in patients with schizophrenia

    Science.gov (United States)

    Aleman, André; de Haan, Edward H.F.; Kahn, René S.

    2005-01-01

    Objective Recent research has revealed a larger impairment of object perceptual discrimination than of spatial perceptual discrimination in patients with schizophrenia. It has been suggested that mental imagery may share processing systems with perception. We investigated whether patients with schizophrenia would show greater impairment regarding object imagery than spatial imagery. Methods Forty-four patients with schizophrenia and 20 healthy control subjects were tested on a task of object visual mental imagery and on a task of spatial visual mental imagery. Both tasks included a condition in which no imagery was needed for adequate performance, but which was in other respects identical to the imagery condition. This allowed us to adjust for nonspecific differences in individual performance. Results The results revealed a significant difference between patients and controls on the object imagery task (F1,63 = 11.8, p = 0.001) but not on the spatial imagery task (F1,63 = 0.14, p = 0.71). To test for a differential effect, we conducted a 2 (patients v. controls) х 2 (object task v. spatial task) analysis of variance. The interaction term was statistically significant (F1,62 = 5.2, p = 0.026). Conclusions Our findings suggest a differential dysfunction of systems mediating object and spatial visual mental imagery in schizophrenia. PMID:15644999

  12. The Effects of Divided Attention on Speech Motor, Verbal Fluency, and Manual Task Performance

    Science.gov (United States)

    Dromey, Christopher; Shim, Erin

    2008-01-01

    Purpose: The goal of this study was to evaluate aspects of the "functional distance hypothesis," which predicts that tasks regulated by brain networks in closer anatomic proximity will interfere more with each other than tasks controlled by spatially distant regions. Speech, verbal fluency, and manual motor tasks were examined to ascertain whether…

  13. Asymmetric cross-domain interference between two working memory tasks : Implications for models of working memory

    NARCIS (Netherlands)

    Morey, Candice C.; Morey, Richard D.; van der Reijden, Madeleine; Holweg, Margot

    2013-01-01

    Observations of higher dual-task costs for within-domain than cross-domain task combinations constitute classic evidence for multi-component models of working memory (e.g., Baddeley, 1986; Logie, 2011). However, we report an asymmetric pattern of interference between verbal and visual-spatial tasks,

  14. How Do Different Aspects of Spatial Skills Relate to Early Arithmetic and Number Line Estimation?

    Directory of Open Access Journals (Sweden)

    Véronique Cornu

    2017-12-01

    Full Text Available The present study investigated the predictive role of spatial skills for arithmetic and number line estimation in kindergarten children (N = 125. Spatial skills are known to be related to mathematical development, but due to the construct’s non-unitary nature, different aspects of spatial skills need to be differentiated. In the present study, a spatial orientation task, a spatial visualization task and visuo-motor integration task were administered to assess three different aspects of spatial skills. Furthermore, we assessed counting abilities, knowledge of Arabic numerals, quantitative knowledge, as well as verbal working memory and verbal intelligence in kindergarten. Four months later, the same children performed an arithmetic and a number line estimation task to evaluate how the abilities measured at Time 1 predicted early mathematics outcomes. Hierarchical regression analysis revealed that children’s performance in arithmetic was predicted by their performance on the spatial orientation and visuo-motor integration task, as well as their knowledge of the Arabic numerals. Performance in number line estimation was significantly predicted by the children’s spatial orientation performance. Our findings emphasize the role of spatial skills, notably spatial orientation, in mathematical development. The relation between spatial orientation and arithmetic was partially mediated by the number line estimation task. Our results further show that some aspects of spatial skills might be more predictive of mathematical development than others, underlining the importance to differentiate within the construct of spatial skills when it comes to understanding numerical development.

  15. The reliability paradox: Why robust cognitive tasks do not produce reliable individual differences.

    Science.gov (United States)

    Hedge, Craig; Powell, Georgina; Sumner, Petroc

    2017-07-19

    Individual differences in cognitive paradigms are increasingly employed to relate cognition to brain structure, chemistry, and function. However, such efforts are often unfruitful, even with the most well established tasks. Here we offer an explanation for failures in the application of robust cognitive paradigms to the study of individual differences. Experimental effects become well established - and thus those tasks become popular - when between-subject variability is low. However, low between-subject variability causes low reliability for individual differences, destroying replicable correlations with other factors and potentially undermining published conclusions drawn from correlational relationships. Though these statistical issues have a long history in psychology, they are widely overlooked in cognitive psychology and neuroscience today. In three studies, we assessed test-retest reliability of seven classic tasks: Eriksen Flanker, Stroop, stop-signal, go/no-go, Posner cueing, Navon, and Spatial-Numerical Association of Response Code (SNARC). Reliabilities ranged from 0 to .82, being surprisingly low for most tasks given their common use. As we predicted, this emerged from low variance between individuals rather than high measurement variance. In other words, the very reason such tasks produce robust and easily replicable experimental effects - low between-participant variability - makes their use as correlational tools problematic. We demonstrate that taking such reliability estimates into account has the potential to qualitatively change theoretical conclusions. The implications of our findings are that well-established approaches in experimental psychology and neuropsychology may not directly translate to the study of individual differences in brain structure, chemistry, and function, and alternative metrics may be required.

  16. Using spatial context to support prospective memory in simulated air traffic control.

    Science.gov (United States)

    Loft, Shayne; Finnerty, Dannielle; Remington, Roger W

    2011-12-01

    The aim was to examine whether prospective memory error and response costs to ongoing tasks in an air traffic control simulation could be reduced by providing spatial context. Prospective memory refers to remembering to perform an intended action at an appropriate point in the future. Failures of prospective memory can occur in air traffic control. For this study, three conditions of participants performed an air traffic control task that required them to accept and hand off aircraft and to prevent conflicts. The prospective memory task required participants to remember to press an alternative key rather than the routine key when accepting target aircraft. A red line separated the display into upper and lower regions. Participants in the context condition were told that the prospective memory instruction would apply only to aircraft approaching from one region (upper or lower). Those in the standard condition were not provided this information. In the control condition, participants did not have to perform the prospective memory task. In the context condition, participants made fewer prospective memory errors than did those in the standard condition and made faster acceptance decisions for aircraft approaching from irrelevant compared with relevant regions. Costs to hand-off decision time were also reduced in the context condition. Spatial context provided no benefit to conflict detection. Participants could partially localize their allocation of attentional resources to the prospective memory task to relevant display regions. The findings are potentially applicable to air traffic control, whereby regularities in airspace structure and standard traffic flows allow controllers to anticipate the location of specific air traffic events.

  17. Primacy Performance of Normal and Retarded Children: Stimulus Familiarity or Spatial Memory?

    Science.gov (United States)

    Swanson, Lee

    1978-01-01

    Explores the effect of stimulus familiarity on the spatial primacy performance of normal and retarded children. Assumes that serial recall tasks reflect spatial memory rather than verbal rehearsal. (BD)

  18. Assessing visuospatial abilities in healthy aging: A novel visuomotor task

    Directory of Open Access Journals (Sweden)

    Natalie eDe Bruin

    2016-02-01

    Full Text Available This study examined the efficacy of a novel reaching-and-grasping task in determining visuospatial abilities across adulthood. The task required male and female young (18-25 years and older adults (60-82 years to replicate a series of complex models by locating and retrieving the appropriate building blocks from an array. The task allows visuospatial complexity to be manipulated independently from the visuomotor demands. Mental rotation and spatial visualisation abilities were assessed. The results showed that the time taken to complete the tasks increased with increased mental rotation complexity. Patterns of hand use were also influenced by the complexity of the models being constructed with right hand use being greater for the less complex models. In addition, although older adults consistently performed the visuomotor tasks slower than the younger adults, their performance was comparable when expressed as the percent change in task demands. This is suggestive that spatial abilities are preserved in older adults. Given the ecologically validity, the described task is an excellent candidate for investigating (1 developmental, (2 sex-based and (3 pathology-based differences in spatial abilities in the visuomotor domain.

  19. Tactile feedback improves auditory spatial localization

    Directory of Open Access Journals (Sweden)

    Monica eGori

    2014-10-01

    Full Text Available Our recent studies suggest that congenitally blind adults have severely impaired thresholds in an auditory spatial-bisection task, pointing to the importance of vision in constructing complex auditory spatial maps (Gori et al., 2014. To explore strategies that may improve the auditory spatial sense in visually impaired people, we investigated the impact of tactile feedback on spatial auditory localization in 48 blindfolded sighted subjects. We measured auditory spatial bisection thresholds before and after training, either with tactile feedback, verbal feedback or no feedback. Audio thresholds were first measured with a spatial bisection task: subjects judged whether the second sound of a three sound sequence was spatially closer to the first or the third sound. The tactile-feedback group underwent two audio-tactile feedback sessions of 100 trials, where each auditory trial was followed by the same spatial sequence played on the subject’s forearm; auditory spatial bisection thresholds were evaluated after each session. In the verbal-feedback condition, the positions of the sounds were verbally reported to the subject after each feedback trial. The no-feedback group did the same sequence of trials, with no feedback. Performance improved significantly only after audio-tactile feedback. The results suggest that direct tactile feedback interacts with the auditory spatial localization system, possibly by a process of cross-sensory recalibration. Control tests with the subject rotated suggested that this effect occurs only when the tactile and acoustic sequences are spatially coherent. Our results suggest that the tactile system can be used to recalibrate the auditory sense of space. These results encourage the possibility of designing rehabilitation programs to help blind persons establish a robust auditory sense of space, through training with the tactile modality.

  20. Alternate superior Julia sets

    International Nuclear Information System (INIS)

    Yadav, Anju; Rani, Mamta

    2015-01-01

    Alternate Julia sets have been studied in Picard iterative procedures. The purpose of this paper is to study the quadratic and cubic maps using superior iterates to obtain Julia sets with different alternate structures. Analytically, graphically and computationally it has been shown that alternate superior Julia sets can be connected, disconnected and totally disconnected, and also fattier than the corresponding alternate Julia sets. A few examples have been studied by applying different type of alternate structures

  1. Handbook of Spatial Statistics

    CERN Document Server

    Gelfand, Alan E

    2010-01-01

    Offers an introduction detailing the evolution of the field of spatial statistics. This title focuses on the three main branches of spatial statistics: continuous spatial variation (point referenced data); discrete spatial variation, including lattice and areal unit data; and, spatial point patterns.

  2. Robot task space analyzer

    International Nuclear Information System (INIS)

    Hamel, W.R.; Osborn, J.

    1997-01-01

    Many nuclear projects such as environmental restoration and waste management challenges involve radiation or other hazards that will necessitate the use of remote operations that protect human workers from dangerous exposures. Remote work is far more costly to execute than what workers could accomplish directly with conventional tools and practices because task operations are slow and tedious due to difficulties of remote manipulation and viewing. Decades of experience within the nuclear remote operations community show that remote tasks may take hundreds of times longer than hands-on work; even with state-of-the-art force- reflecting manipulators and television viewing, remote task performance execution is five to ten times slower than equivalent direct contact work. Thus the requirement to work remotely is a major cost driver in many projects. Modest improvements in the work efficiency of remote systems can have high payoffs by reducing the completion time of projects. Additional benefits will accrue from improved work quality and enhanced safety

  3. Performing Task Integration

    DEFF Research Database (Denmark)

    Elkjaer, Bente; Nickelsen, Niels Christian Mossfeldt

    by shared goals and knowledge as well as mutual respect and frequent, timely, accurate and problem-solving ways of communication with the purpose of dealing with the tasks at hand in an integrated way. We introduce and discuss relational coordination theory through a case-study within public healthcare....... Here cross-professional coordination of work was done by scheduled communication twice a day. When we proposed a way for further integration of tasks through an all-inclusive team organization, we were met with resistance. We use the study to discuss whether relational coordination theory is able to do...... away with differences regarding task definitions and working conditions as well as professional knowledge hierarchies and responsibilities for parts and wholes....

  4. Spatial Experiences of High Academic Achievers: Insights from a Developmental Perspective

    Science.gov (United States)

    Weckbacher, Lisa Marie; Okamoto, Yukari

    2012-01-01

    The study explored the relationship between types of spatial experiences and spatial abilities among 13- to 14-year-old high academic achievers. Each participant completed two spatial tasks and a survey assessing favored spatial activities across five categories (computers, toys, sports, music, and art) and three developmental periods (early…

  5. Organizing Core Tasks

    DEFF Research Database (Denmark)

    Boll, Karen

    has remained much the same within the last 10 years. However, how the core task has been organized has changed considerable under the influence of various “organizing devices”. The paper focusses on how organizing devices such as risk assessment, output-focus, effect orientation, and treatment...... projects influence the organization of core tasks within the tax administration. The paper shows that the organizational transformations based on the use of these devices have had consequences both for the overall collection of revenue and for the employees’ feeling of “making a difference”. All in all...

  6. Object orientation affects spatial language comprehension.

    Science.gov (United States)

    Burigo, Michele; Sacchi, Simona

    2013-01-01

    Typical spatial descriptions, such as "The car is in front of the house," describe the position of a located object (LO; e.g., the car) in space relative to a reference object (RO) whose location is known (e.g., the house). The orientation of the RO affects spatial language comprehension via the reference frame selection process. However, the effects of the LO's orientation on spatial language have not received great attention. This study explores whether the pure geometric information of the LO (e.g., its orientation) affects spatial language comprehension using placing and production tasks. Our results suggest that the orientation of the LO influences spatial language comprehension even in the absence of functional relationships. Copyright © 2013 Cognitive Science Society, Inc.

  7. Spatial Management Areas

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Spatial management files combine all related and relevant spatial management files into an integrated fisheries management file. Overlaps of the redundant spatial...

  8. Organizational and operational models for certificate management entities as part of the connected vehicle program : revised working paper (task 2).

    Science.gov (United States)

    1997-01-01

    This report summarizes the efforts performed under subtasks D&E of the ATIS Communications Technology Alternatives Task for the FHWA Turner Fairbank Highway Research Center. Tasks D & E were to facilitate further examination of wireless communication...

  9. Think3d!: Improving mathematics learning through embodied spatial training.

    Science.gov (United States)

    Burte, Heather; Gardony, Aaron L; Hutton, Allyson; Taylor, Holly A

    2017-01-01

    Spatial thinking skills positively relate to Science, Technology, Engineering, and Math (STEM) outcomes, but spatial training is largely absent in elementary school. Elementary school is a time when children develop foundational cognitive skills that will support STEM learning throughout their education. Spatial thinking should be considered a foundational cognitive skill. The present research examined the impact of an embodied spatial training program on elementary students' spatial and mathematical thinking. Students in rural elementary schools completed spatial and math assessments prior to and after participating in an origami and pop-up paper engineering-based program, called Think3d!. Think3d! uses embodied tasks, such as folding and cutting paper, to train two-dimensional to three-dimensional spatial thinking. Analyses explored spatial thinking gains, mathematics gains - specifically for problem types expected to show gains from spatial training - and factors predicting mathematics gains. Results showed spatial thinking gains in two assessments. Using a math categorization to target problems more and less likely to be impacted by spatial training, we found that all students improved on real-world math problems and older students improved on visual and spatial math problems. Further, the results are suggestive of developmental time points for implementing embodied spatial training related to applying spatial thinking to math. Finally, the spatial thinking assessment that was most highly related to training activities also predicted math performance gains. Future research should explore developmental issues related to how embodied spatial training might support STEM learning and outcomes.

  10. Data Center Tasking.

    Science.gov (United States)

    Temares, M. Lewis; Lutheran, Joseph A.

    Operations tasking for data center management is discussed. The original and revised organizational structures of the data center at the University of Miami are also described. The organizational strategy addresses the functions that should be performed by the data center, anticipates the specialized skills required, and addresses personnel…

  11. Biomedical applications engineering tasks

    Science.gov (United States)

    Laenger, C. J., Sr.

    1976-01-01

    The engineering tasks performed in response to needs articulated by clinicians are described. Initial contacts were made with these clinician-technology requestors by the Southwest Research Institute NASA Biomedical Applications Team. The basic purpose of the program was to effectively transfer aerospace technology into functional hardware to solve real biomedical problems.

  12. India's Unfinished Telecom Tasks

    Indian Academy of Sciences (India)

    India's Telecom Story is now well known · Indian Operators become an enviable force · At the same time · India Amongst the Leaders · Unfinished Tasks as Operators · LightGSM ON: Innovation for Rural Area from Midas · Broadband Access Options for India · Broadband driven by DSL: still too slow · Is Wireless the answer?

  13. Plasmonic computing of spatial differentiation

    Science.gov (United States)

    Zhu, Tengfeng; Zhou, Yihan; Lou, Yijie; Ye, Hui; Qiu, Min; Ruan, Zhichao; Fan, Shanhui

    2017-05-01

    Optical analog computing offers high-throughput low-power-consumption operation for specialized computational tasks. Traditionally, optical analog computing in the spatial domain uses a bulky system of lenses and filters. Recent developments in metamaterials enable the miniaturization of such computing elements down to a subwavelength scale. However, the required metamaterial consists of a complex array of meta-atoms, and direct demonstration of image processing is challenging. Here, we show that the interference effects associated with surface plasmon excitations at a single metal-dielectric interface can perform spatial differentiation. And we experimentally demonstrate edge detection of an image without any Fourier lens. This work points to a simple yet powerful mechanism for optical analog computing at the nanoscale.

  14. Plasmonic computing of spatial differentiation.

    Science.gov (United States)

    Zhu, Tengfeng; Zhou, Yihan; Lou, Yijie; Ye, Hui; Qiu, Min; Ruan, Zhichao; Fan, Shanhui

    2017-05-19

    Optical analog computing offers high-throughput low-power-consumption operation for specialized computational tasks. Traditionally, optical analog computing in the spatial domain uses a bulky system of lenses and filters. Recent developments in metamaterials enable the miniaturization of such computing elements down to a subwavelength scale. However, the required metamaterial consists of a complex array of meta-atoms, and direct demonstration of image processing is challenging. Here, we show that the interference effects associated with surface plasmon excitations at a single metal-dielectric interface can perform spatial differentiation. And we experimentally demonstrate edge detection of an image without any Fourier lens. This work points to a simple yet powerful mechanism for optical analog computing at the nanoscale.

  15. Leftward spatial bias in children's drawing placement: hemispheric activation versus directional hypotheses.

    Science.gov (United States)

    Picard, Delphine; Zarhbouch, Benaissa

    2014-01-01

    A leftward spatial bias in drawing placement was demonstrated by Heller (1991) using the draw-a-person test with right-handed American children. No such bias was observed in left-handed children who are assumed to be less lateralised than their right-handed peers. According to Heller the leftward spatial bias is primarily a reflection of the right hemisphere specialisation for spatial processing. However, an alternative explanation in terms of directional trends may be put forward. In the present study we first confirm Heller's findings of a handedness effect on drawing placement using the draw-a-tree task with a large sample of right- and left-handed French children aged 5-15 years (Exp. 1). We then provide evidence that a similar leftward bias occurs in right-handed Moroccan children aged 7-11 years with opposite script directionality and opposite preferred drawing movement directions (i.e., right-to-left directional trends) to the those of right-handed French children (Exp. 2). Taken together these findings suggest that directionality trends arising from learned cultural habits and motor preferences play little role in determining spatial bias in the centring of a single object drawn on a page. Rather there may be a cerebral origin for drawing single objects slightly on the left side of the graphic space.

  16. Acute administration of THC impairs spatial but not associative memory function in zebrafish.

    Science.gov (United States)

    Ruhl, Tim; Prinz, Nicole; Oellers, Nadine; Seidel, Nathan Ian; Jonas, Annika; Albayram, Onder; Bilkei-Gorzo, Andras; von der Emde, Gerhard

    2014-10-01

    The present study examined the effect of acute administration of endocannabinoid receptor CB1 ligand ∆-9-tetrahydrocannabinol (THC) on intracellular signalling in the brain and retrieval from two different memory systems in the zebrafish (Danio rerio). First, fish were treated with THC and changes in the phosphorylation level of mitogen-activated protein (MAP) kinases Akt and Erk in the brain were determined 1 h after drug treatment. Next, animals of a second group learned in a two-alternative choice paradigm to discriminate between two colours, whereas a third group solved a spatial cognition task in an open-field maze by use of an ego-allocentric strategy. After memory acquisition and consolidation, animals were pharmacologically treated using the treatment regime as in the first group and then tested again for memory retrieval. We found an enhanced Erk but not Akt phosphorylation suggesting that THC treatment specifically activated Erk signalling in the zebrafish telencephalon. While CB1 agonist THC did not affect behavioural performance of animals in the colour discrimination paradigm, spatial memory was significantly impaired. The effect of THC on spatial learning is probably specific, since neither motor activity nor anxiety-related behaviour was influenced by the drug treatment. That indicates a striking influence of the endocannabinoid system (ECS) on spatial cognition in zebrafish. The results are very coincident with reports on mammals, demonstrating that the ECS is functional highly conserved during vertebrate evolution. We further conclude that the zebrafish provides a promising model organism for ongoing research on the ECS.

  17. Modelling response times in multi-alternative categorization with TVA

    DEFF Research Database (Denmark)

    Blurton, Steven Paul; Kyllingsbæk, Søren; Bundesen, Claus

    , such as trial-to-trial variation in the Poisson processing rates and an extension of the random walk to n-alternatives. In an empirical test of the model we fitted the random walk model to data of a binary and a four-alternative orientation discrimination task. In both cases, the model predictions closely...

  18. Complementary and Alternative Medicine

    Science.gov (United States)

    ... for Educators Search English Español Complementary and Alternative Medicine KidsHealth / For Teens / Complementary and Alternative Medicine What's ... a replacement. How Is CAM Different From Conventional Medicine? Conventional medicine is based on scientific knowledge of ...

  19. Microprocessor multi-task monitor

    International Nuclear Information System (INIS)

    Ludemann, C.A.

    1983-01-01

    This paper describes a multi-task monitor program for microprocessors. Although written for the Intel 8085, it incorporates features that would be beneficial for implementation in other microprocessors used in controlling and monitoring experiments and accelerators. The monitor places permanent programs (tasks) arbitrarily located throughout ROM in a priority ordered queue. The programmer is provided with the flexibility to add new tasks or modified versions of existing tasks, without having to comply with previously defined task boundaries or having to reprogram all of ROM. Scheduling of tasks is triggered by timers, outside stimuli (interrupts), or inter-task communications. Context switching time is of the order of tenths of a milllisecond

  20. Cultural and Gender Differences in Spatial Ability of Young Children.

    Science.gov (United States)

    Seng, Alice Seok Hoon; Tan, Lee Choo

    This study reports on cultural and gender differences in the spatial abilities of children based on the Water Level Task. The Piagetian theory of age-related developmental differences in performance on the Water Level Task was explored with Chinese and Malay children living in Singapore. Results indicate that children in this study did not perform…

  1. Alternative way of life

    International Nuclear Information System (INIS)

    Fischer, C.

    1980-01-01

    The volume describes the reasons why more and more people seek alternative ways of life, the theoretical background and what alternative life means in practice as well as the sociological significance and history of the alternative movement. It also contains statements of persons who have 'got out' and advice on energy-saving. (HSCH) [de

  2. Bayesian Spatial Modelling with R-INLA

    Directory of Open Access Journals (Sweden)

    Finn Lindgren

    2015-02-01

    Full Text Available The principles behind the interface to continuous domain spatial models in the R- INLA software package for R are described. The integrated nested Laplace approximation (INLA approach proposed by Rue, Martino, and Chopin (2009 is a computationally effective alternative to MCMC for Bayesian inference. INLA is designed for latent Gaussian models, a very wide and flexible class of models ranging from (generalized linear mixed to spatial and spatio-temporal models. Combined with the stochastic partial differential equation approach (SPDE, Lindgren, Rue, and Lindstrm 2011, one can accommodate all kinds of geographically referenced data, including areal and geostatistical ones, as well as spatial point process data. The implementation interface covers stationary spatial mod- els, non-stationary spatial models, and also spatio-temporal models, and is applicable in epidemiology, ecology, environmental risk assessment, as well as general geostatistics.

  3. Dynamic, continuous multitasking training leads to task-specific improvements but does not transfer across action selection tasks

    Science.gov (United States)

    Bender, Angela D.; Filmer, Hannah L.; Naughtin, Claire K.; Dux, Paul E.

    2017-12-01

    The ability to perform multiple tasks concurrently is an ever-increasing requirement in our information-rich world. Despite this, multitasking typically compromises performance due to the processing limitations associated with cognitive control and decision-making. While intensive dual-task training is known to improve multitasking performance, only limited evidence suggests that training-related performance benefits can transfer to untrained tasks that share overlapping processes. In the real world, however, coordinating and selecting several responses within close temporal proximity will often occur in high-interference environments. Over the last decade, there have been notable reports that training on video action games that require dynamic multitasking in a demanding environment can lead to transfer effects on aspects of cognition such as attention and working memory. Here, we asked whether continuous and dynamic multitasking training extends benefits to tasks that are theoretically related to the trained tasks. To examine this issue, we asked a group of participants to train on a combined continuous visuomotor tracking task and a perceptual discrimination task for six sessions, while an active control group practiced the component tasks in isolation. A battery of tests measuring response selection, response inhibition, and spatial attention was administered before and immediately after training to investigate transfer. Multitasking training resulted in substantial, task-specific gains in dual-task ability, but there was no evidence that these benefits generalized to other action control tasks. The findings suggest that training on a combined visuomotor tracking and discrimination task results in task-specific benefits but provides no additional value for untrained action selection tasks.

  4. The neural basis of task switching changes with skill acquisition

    Directory of Open Access Journals (Sweden)

    Koji eJimura

    2014-05-01

    Full Text Available Learning novel skills involves reorganization and optimization of cognitive processing involving a broad network of brain regions. Previous work has shown asymmetric costs of switching to a well-trained task versus a poorly-trained task, but the neural basis of these differential switch costs is unclear. The current study examined the neural signature of task switching in the context of acquisition of new skill. Human participants alternated randomly between a novel visual task (mirror-reversed word reading and a highly practiced one (plain word reading, allowing the isolation of task switching and skill set maintenance. Two scan sessions were separated by two weeks, with behavioral training on the mirror reading task in between the two sessions. Broad cortical regions, including bilateral prefrontal, parietal, and extrastriate cortices, showed decreased activity associated with learning of the mirror reading skill. In contrast, learning to switch to the novel skill was associated with decreased activity in a focal subcortical region in the dorsal striatum. Switching to the highly practiced task was associated with a non-overlapping set of regions, suggesting substantial differences in the neural substrates of switching as a function of task skill. Searchlight multivariate pattern analysis also revealed that learning was associated with decreased pattern information for mirror versus plain reading tasks in fronto-parietal regions. Inferior frontal junction and posterior parietal cortex showed a joint effect of univariate activation and pattern information. These results suggest distinct learning mechanisms task performance and executive control as a function of learning.

  5. Task Force report

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    The International Task Force on Prevention of Nuclear Terrorism was formed in 1985 under the auspices of the Nuclear Control Institute. This report is a consensus report of the 26 task force members - all members not necessarily agreeing on every point and all wordings, but in each case a substantial majority did agree. First, the report defines the threat, then establishes the priorities. Short-term recommendations are presented on: (1) protecting nuclear weapons; (2) protecting nuclear materials; (3) protecting nuclear facilities; (4) intelligence programs; (5) civil liberties concerns; (6) controlling nuclear transfers; (7) US - Soviet cooperation; (8) arms control initiatives; (9) convention of physical protection of nuclear material; (10) role of emergency management programs; and (11) role of the media. Brief long-term recommendations are included on (1) international measures, and (2) emerging nuclear technologies. An Appendix, Production of Nuclear Materials Usable in Weapons is presented for further consideration (without recommendations)

  6. Rostering and Task Scheduling

    DEFF Research Database (Denmark)

    Dohn, Anders Høeg

    . The rostering process is non-trivial and especially when service is required around the clock, rostering may involve considerable effort from a designated planner. Therefore, in order to minimize costs and overstaffing, to maximize the utilization of available staff, and to ensure a high level of satisfaction...... as possible to the available staff, while respecting various requirements and rules and while including possible transportation time between tasks. This thesis presents a number of industrial applications in rostering and task scheduling. The applications exist within various contexts in health care....... Mathematical and logic-based models are presented for the problems considered. Novel components are added to existing models and the modeling decisions are justified. In one case, the model is solved by a simple, but efficient greedy construction heuristic. In the remaining cases, column generation is applied...

  7. Hemispheric Lateralization of Verbal and Spatial Working Memory during Adolescence

    Science.gov (United States)

    Nagel, Bonnie J.; Herting, Megan M.; Maxwell, Emily C.; Bruno, Richard; Fair, Damien

    2013-01-01

    Adult functional magnetic resonance imaging (fMRI) literature suggests that a left-right hemispheric dissociation may exist between verbal and spatial working memory (WM), respectively. However, investigation of this type has been obscured by incomparable verbal and spatial WM tasks and/or visual inspection at arbitrary thresholds as means to…

  8. Music Exposure and the Development of Spatial Intelligence in Children.

    Science.gov (United States)

    Rauscher, Frances H.

    1999-01-01

    Presents research on the effects of music instruction on spatial-temporal reasoning in children. Summarizes past studies that tested whether music training transfers to spatial-temporal task performance. A work-in-progress focuses on whether music training can improve economically-disadvantaged preschoolers' abstract reasoning and why…

  9. A Novel Fixed Low-Rank Constrained EEG Spatial Filter Estimation with Application to Movie-Induced Emotion Recognition

    Directory of Open Access Journals (Sweden)

    Ken Yano

    2016-01-01

    Full Text Available This paper proposes a novel fixed low-rank spatial filter estimation for brain computer interface (BCI systems with an application that recognizes emotions elicited by movies. The proposed approach unifies such tasks as feature extraction, feature selection, and classification, which are often independently tackled in a “bottom-up” manner, under a regularized loss minimization problem. The loss function is explicitly derived from the conventional BCI approach and solves its minimization by optimization with a nonconvex fixed low-rank constraint. For evaluation, an experiment was conducted to induce emotions by movies for dozens of young adult subjects and estimated the emotional states using the proposed method. The advantage of the proposed method is that it combines feature selection, feature extraction, and classification into a monolithic optimization problem with a fixed low-rank regularization, which implicitly estimates optimal spatial filters. The proposed method shows competitive performance against the best CSP-based alternatives.

  10. A Comparative Study of Task-based vs. Task- supported Teaching Approaches in an EFL Context

    Directory of Open Access Journals (Sweden)

    Mahdieh Shafipoor

    2015-09-01

    Full Text Available In spite of the numerous merits of task-based language instruction as claimed by its supporters in the last few decades, task-supported teaching approach as an alternative was introduced. Since then, there have been controversial debates over the superiority of each of these two approaches. Thus, in the current research project, the purpose was to consider these two teaching approaches in the scope of English language teaching, with the purpose of exploring the most efficient one in an Iranian EFL context. To this end, 120 sophomore students, majoring in English language translation course at Islamic Azad University, Shar-e-Qods branch were selected among 4 intact reading comprehension II classes. Next, they were divided into two experimental groups. The first experimental group received task-based instruction and for the second experimental group, task-trusted teaching approach was applied. The results of the data analyses turned out that task-trusted teaching approach was superior to task-based teaching in teaching reading to EFL learners.

  11. The task force process

    International Nuclear Information System (INIS)

    Applegate, J.S.

    1995-01-01

    This paper focuses on the unique aspects of the Fernald Citizens Task Force process that have contributed to a largely successful public participation effort at Fernald. The Fernald Citizens Task Force passed quickly by many procedural issues. Instead, the Task Force concentrated on (a) educating itself about the site, its problems, and possible solutions, and (b) choosing a directed way to approach its mandate: To make recommendations on several open-quotes big pictureclose quotes issues, including future use of the site, cleanup levels, waste disposition, and cleanup priorities. This paper presents the approach used at Fernald for establishing and running a focused site-specific advisory board, the key issues that have been faced, and how these issues were resolved. The success of Fernald in establishing a strong and functioning site-specific advisory board serves as a useful model for other DOE facilities, although the Fernald model is just one of many approaches that can be taken. However, the approach presented here has worked extremely well for Fernald

  12. Gap Task Force

    CERN Multimedia

    Lissuaer, D

    One of the more congested areas in the ATLAS detector is the GAP region (the area between the Barrel Calorimeter and the End Cap calorimeter) where Inner Detector services, LAr Services and some Tile services all must co-habitat in a very limited area. It has been clear for some time that the space in the GAP region is not sufficient to accommodate all that is needed. In the last few month additional problems of routing all the services to Z=0 have been encountered due to the very limited space between the Tile Calorimeter and the first layer of Muon chambers. The Technical Management Board (TMB) and the Executive Board (EB) decided in the middle of March to establish a Task Force to look at this problem and come up with a solution within well-specified guidelines. The task force consisted of experts from the ID, Muon, Liquid Argon and Tile systems in addition to experts from the Technical Coordination team and the Physics coordinator. The task force held many meetings and in general there were some very l...

  13. Mobile Thread Task Manager

    Science.gov (United States)

    Clement, Bradley J.; Estlin, Tara A.; Bornstein, Benjamin J.

    2013-01-01

    The Mobile Thread Task Manager (MTTM) is being applied to parallelizing existing flight software to understand the benefits and to develop new techniques and architectural concepts for adapting software to multicore architectures. It allocates and load-balances tasks for a group of threads that migrate across processors to improve cache performance. In order to balance-load across threads, the MTTM augments a basic map-reduce strategy to draw jobs from a global queue. In a multicore processor, memory may be "homed" to the cache of a specific processor and must be accessed from that processor. The MTTB architecture wraps access to data with thread management to move threads to the home processor for that data so that the computation follows the data in an attempt to avoid L2 cache misses. Cache homing is also handled by a memory manager that translates identifiers to processor IDs where the data will be homed (according to rules defined by the user). The user can also specify the number of threads and processors separately, which is important for tuning performance for different patterns of computation and memory access. MTTM efficiently processes tasks in parallel on a multiprocessor computer. It also provides an interface to make it easier to adapt existing software to a multiprocessor environment.

  14. LHCb computing tasks

    CERN Document Server

    Binko, P

    1998-01-01

    This document describes the computing tasks of the LHCb computing system. It also describes the logistics of the dataflow between the tasks and the detailed requirements for each task, in particular the data sizes and CPU power requirements. All data sizes are calculated assuming that the LHCb experiment will take data about 107 s per year at a frequency of 200 Hz, which gives 2 \\Theta 109 real events per year. The raw event size should not exceed 100 kB (200 TB per year). We will have to generate about 109 MonteCarlo events per year. The current MonteCarlo simulation program based on the GEANT3.21 package requires about 12 s to produce an average event (all CPU times are normalised to a 1000 MIPS processor). The size of an average MonteCarlo event will be about 200 kB (100 TB per year) of simulated data (without the hits). We will start to use the GEANT4 package in 1998. Rejection factors of 8 and 25 are required in the Level-2 and Level-3 triggers respectively, to reduce the frequency of events to 200 Hz. T...

  15. Tactile spatial resolution in blind braille readers.

    Science.gov (United States)

    Van Boven, R W; Hamilton, R H; Kauffman, T; Keenan, J P; Pascual-Leone, A

    2000-06-27

    To determine if blind people have heightened tactile spatial acuity. Recently, studies using magnetic source imaging and somatosensory evoked potentials have shown that the cortical representation of the reading fingers of blind Braille readers is expanded compared to that of fingers of sighted subjects. Furthermore, the visual cortex is activated during certain tactile tasks in blind subjects but not sighted subjects. The authors hypothesized that the expanded cortical representation of fingers used in Braille reading may reflect an enhanced fidelity in the neural transmission of spatial details of a stimulus. If so, the quantitative limit of spatial acuity would be superior in blind people. The authors employed a grating orientation discrimination task in which threshold performance is accounted for by the spatial resolution limits of the neural image evoked by a stimulus. The authors quantified the psychophysical limits of spatial acuity at the middle and index fingers of 15 blind Braille readers and 15 sighted control subjects. The mean grating orientation threshold was significantly (p = 0.03) lower in the blind group (1.04 mm) compared to the sighted group (1.46 mm). The self-reported dominant reading finger in blind subjects had a mean grating orientation threshold of 0.80 mm, which was significantly better than other fingers tested. Thresholds at non-Braille reading fingers in blind subjects averaged 1.12 mm, which were also superior to sighted subjects' performances. Superior tactile spatial acuity in blind Braille readers may represent an adaptive, behavioral correlate of cortical plasticity.

  16. Task analysis and support for problem solving tasks

    International Nuclear Information System (INIS)

    Bainbridge, L.

    1987-01-01

    This paper is concerned with Task Analysis as the basis for ergonomic design to reduce human error rates, rather than for predicting human error rates. Task Analysis techniques usually provide a set of categories for describing sub tasks, and a framework describing the relations between sub-tasks. Both the task type categories and their organisation have implications for optimum interface and training design. In this paper, the framework needed for considering the most complex tasks faced by operators in process industries is discussed such as fault management in unexpected situations, and what is likely to minimise human error in these circumstances. (author)

  17. Spatial econometrics using microdata

    CERN Document Server

    Dubé, Jean

    2014-01-01

    This book provides an introduction to spatial analyses concerning disaggregated (or micro) spatial data.Particular emphasis is put on spatial data compilation and the structuring of the connections between the observations. Descriptive analysis methods of spatial data are presented in order to identify and measure the spatial, global and local dependency.The authors then focus on autoregressive spatial models, to control the problem of spatial dependency between the residues of a basic linear statistical model, thereby contravening one of the basic hypotheses of the ordinary least squares appr

  18. Depleted uranium management alternatives

    Energy Technology Data Exchange (ETDEWEB)

    Hertzler, T.J.; Nishimoto, D.D.

    1994-08-01

    This report evaluates two management alternatives for Department of Energy depleted uranium: continued storage as uranium hexafluoride, and conversion to uranium metal and fabrication to shielding for spent nuclear fuel containers. The results will be used to compare the costs with other alternatives, such as disposal. Cost estimates for the continued storage alternative are based on a life-cycle of 27 years through the year 2020. Cost estimates for the recycle alternative are based on existing conversion process costs and Capital costs for fabricating the containers. Additionally, the recycle alternative accounts for costs associated with intermediate product resale and secondary waste disposal for materials generated during the conversion process.

  19. Depleted uranium management alternatives

    International Nuclear Information System (INIS)

    Hertzler, T.J.; Nishimoto, D.D.

    1994-08-01

    This report evaluates two management alternatives for Department of Energy depleted uranium: continued storage as uranium hexafluoride, and conversion to uranium metal and fabrication to shielding for spent nuclear fuel containers. The results will be used to compare the costs with other alternatives, such as disposal. Cost estimates for the continued storage alternative are based on a life-cycle of 27 years through the year 2020. Cost estimates for the recycle alternative are based on existing conversion process costs and Capital costs for fabricating the containers. Additionally, the recycle alternative accounts for costs associated with intermediate product resale and secondary waste disposal for materials generated during the conversion process

  20. Males and females differ in brain activation during cognitive tasks.

    Science.gov (United States)

    Bell, Emily C; Willson, Morgan C; Wilman, Alan H; Dave, Sanjay; Silverstone, Peter H

    2006-04-01

    To examine the effect of gender on regional brain activity, we utilized functional magnetic resonance imaging (fMRI) during a motor task and three cognitive tasks; a word generation task, a spatial attention task, and a working memory task in healthy male (n = 23) and female (n = 10) volunteers. Functional data were examined for group differences both in the number of pixels activated, and the blood-oxygen-level-dependent (BOLD) magnitude during each task. Males had a significantly greater mean activation than females in the working memory task with a greater number of pixels being activated in the right superior parietal gyrus and right inferior occipital gyrus, and a greater BOLD magnitude occurring in the left inferior parietal lobe. However, despite these fMRI changes, there were no significant differences between males and females on cognitive performance of the task. In contrast, in the spatial attention task, men performed better at this task than women, but there were no significant functional differences between the two groups. In the word generation task, there were no external measures of performance, but in the functional measurements, males had a significantly greater mean activation than females, where males had a significantly greater BOLD signal magnitude in the left and right dorsolateral prefrontal cortex, the right inferior parietal lobe, and the cingulate. In neither of the motor tasks (right or left hand) did males and females perform differently. Our fMRI findings during the motor tasks were a greater mean BOLD signal magnitude in males in the right hand motor task, compared to females where males had an increased BOLD signal magnitude in the right inferior parietal gyrus and in the left inferior frontal gyrus. In conclusion, these results demonstrate differential patterns of activation in males and females during a variety of cognitive tasks, even though performance in these tasks may not vary, and also that variability in performance may not

  1. Effects of noise and task loading on a communication task loading on a communication task

    Science.gov (United States)

    Orrell, Dean H., II

    Previous research had shown the effect of noise on a single communication task. This research has been criticized as not being representative of a real world situation since subjects allocated all of their attention to only one task. In the present study, the effect of adding a loading task to a standard noise-communication paradigm was investigated. Subjects performed both a communication task (Modified Rhyme Test; House et al. 1965) and a short term memory task (Sternberg, 1969) in simulated levels of aircraft noise (95, 105 and 115 dB overall sound pressure level (OASPL)). Task loading was varied with Sternberg's task by requiring subjects to memorize one, four, or six alphanumeric characters. Simulated aircraft noise was varied between levels of 95, 105 and 115 dB OASPL using a pink noise source. Results show that the addition of Sternberg's task and little effect on the intelligibility of the communication task while response time for the communication task increased.

  2. From "rest" to language task: Task activation selects and prunes from broader resting-state network.

    Science.gov (United States)

    Doucet, Gaelle E; He, Xiaosong; Sperling, Michael R; Sharan, Ashwini; Tracy, Joseph I

    2017-05-01

    Resting-state networks (RSNs) show spatial patterns generally consistent with networks revealed during cognitive tasks. However, the exact degree of overlap between these networks has not been clearly quantified. Such an investigation shows promise for decoding altered functional connectivity (FC) related to abnormal language functioning in clinical populations such as temporal lobe epilepsy (TLE). In this context, we investigated the network configurations during a language task and during resting state using FC. Twenty-four healthy controls, 24 right and 24 left TLE patients completed a verb generation (VG) task and a resting-state fMRI scan. We compared the language network revealed by the VG task with three FC-based networks (seeding the left inferior frontal cortex (IFC)/Broca): two from the task (ON, OFF blocks) and one from the resting state. We found that, for both left TLE patients and controls, the RSN recruited regions bilaterally, whereas both VG-on and VG-off conditions produced more left-lateralized FC networks, matching more closely with the activated language network. TLE brings with it variability in both task-dependent and task-independent networks, reflective of atypical language organization. Overall, our findings suggest that our RSN captured bilateral activity, reflecting a set of prepotent language regions. We propose that this relationship can be best understood by the notion of pruning or winnowing down of the larger language-ready RSN to carry out specific task demands. Our data suggest that multiple types of network analyses may be needed to decode the association between language deficits and the underlying functional mechanisms altered by disease. Hum Brain Mapp 38:2540-2552, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  3. Spatial Thinking in Atmospheric Science Education

    Science.gov (United States)

    McNeal, P. M.; Petcovic, H. L.; Ellis, T. D.

    2016-12-01

    Atmospheric science is a STEM discipline that involves the visualization of three-dimensional processes from two-dimensional maps, interpretation of computer-generated graphics and hand plotting of isopleths. Thus, atmospheric science draws heavily upon spatial thinking. Research has shown that spatial thinking ability can be a predictor of early success in STEM disciplines and substantial evidence demonstrates that spatial thinking ability is improved through various interventions. Therefore, identification of the spatial thinking skills and cognitive processes used in atmospheric science is the first step toward development of instructional strategies that target these skills and scaffold the learning of students in atmospheric science courses. A pilot study of expert and novice meteorologists identified mental animation and disembedding as key spatial skills used in the interpretation of multiple weather charts and images. Using this as a starting point, we investigated how these spatial skills, together with expertise, domain specific knowledge, and working memory capacity affect the ability to produce an accurate forecast. Participants completed a meteorology concept inventory, experience questionnaire and psychometric tests of spatial thinking ability and working memory capacity prior to completing a forecasting task. A quantitative analysis of the collected data investigated the effect of the predictor variables on the outcome task. A think-aloud protocol with individual participants provided a qualitative look at processes such as task decomposition, rule-based reasoning and the formation of mental models in an attempt to understand how individuals process this complex data and describe outcomes of particular meteorological scenarios. With our preliminary results we aim to inform atmospheric science education from a cognitive science perspective. The results point to a need to collaborate with the atmospheric science community broadly, such that multiple

  4. An opportunity cost model of subjective effort and task performance

    Science.gov (United States)

    Kurzban, Robert; Duckworth, Angela; Kable, Joseph W.; Myers, Justus

    2013-01-01

    Why does performing certain tasks cause the aversive experience of mental effort and concomitant deterioration in task performance? One explanation posits a physical resource that is depleted over time. We propose an alternate explanation that centers on mental representations of the costs and benefits associated with task performance. Specifically, certain computational mechanisms, especially those associated with executive function, can be deployed for only a limited number of simultaneous tasks at any given moment. Consequently, the deployment of these computational mechanisms carries an opportunity cost – that is, the next-best use to which these systems might be put. We argue that the phenomenology of effort can be understood as the felt output of these cost/benefit computations. In turn, the subjective experience of effort motivates reduced deployment of these computational mechanisms in the service of the present task. These opportunity cost representations, then, together with other cost/benefit calculations, determine effort expended and, everything else equal, result in performance reductions. In making our case for this position, we review alternate explanations both for the phenomenology of effort associated with these tasks and for performance reductions over time. Likewise, we review the broad range of relevant empirical results from across subdisciplines, especially psychology and neuroscience. We hope that our proposal will help to build links among the diverse fields that have been addressing similar questions from different perspectives, and we emphasize ways in which alternate models might be empirically distinguished. PMID:24304775

  5. Assessing implicit odor localization in humans using a cross-modal spatial cueing paradigm.

    Science.gov (United States)

    Moessnang, Carolin; Finkelmeyer, Andreas; Vossen, Alexandra; Schneider, Frank; Habel, Ute

    2011-01-01

    Navigation based on chemosensory information is one of the most important skills in the animal kingdom. Studies on odor localization suggest that humans have lost this ability. However, the experimental approaches used so far were limited to explicit judgements, which might ignore a residual ability for directional smelling on an implicit level without conscious appraisal. A novel cueing paradigm was developed in order to determine whether an implicit ability for directional smelling exists. Participants performed a visual two-alternative forced choice task in which the target was preceded either by a side-congruent or a side-incongruent olfactory spatial cue. An explicit odor localization task was implemented in a second experiment. No effect of cue congruency on mean reaction times could be found. However, a time by condition interaction emerged, with significantly slower responses to congruently compared to incongruently cued targets at the beginning of the experiment. This cueing effect gradually disappeared throughout the course of the experiment. In addition, participants performed at chance level in the explicit odor localization task, thus confirming the results of previous research. The implicit cueing task suggests the existence of spatial information processing in the olfactory system. Response slowing after a side-congruent olfactory cue is interpreted as a cross-modal attentional interference effect. In addition, habituation might have led to a gradual disappearance of the cueing effect. It is concluded that under immobile conditions with passive monorhinal stimulation, humans are unable to explicitly determine the location of a pure odorant. Implicitly, however, odor localization seems to exert an influence on human behaviour. To our knowledge, these data are the first to show implicit effects of odor localization on overt human behaviour and thus support the hypothesis of residual directional smelling in humans. © 2011 Moessnang et al.

  6. Assessing implicit odor localization in humans using a cross-modal spatial cueing paradigm.

    Directory of Open Access Journals (Sweden)

    Carolin Moessnang

    Full Text Available Navigation based on chemosensory information is one of the most important skills in the animal kingdom. Studies on odor localization suggest that humans have lost this ability. However, the experimental approaches used so far were limited to explicit judgements, which might ignore a residual ability for directional smelling on an implicit level without conscious appraisal.A novel cueing paradigm was developed in order to determine whether an implicit ability for directional smelling exists. Participants performed a visual two-alternative forced choice task in which the target was preceded either by a side-congruent or a side-incongruent olfactory spatial cue. An explicit odor localization task was implemented in a second experiment.No effect of cue congruency on mean reaction times could be found. However, a time by condition interaction emerged, with significantly slower responses to congruently compared to incongruently cued targets at the beginning of the experiment. This cueing effect gradually disappeared throughout the course of the experiment. In addition, participants performed at chance level in the explicit odor localization task, thus confirming the results of previous research.The implicit cueing task suggests the existence of spatial information processing in the olfactory system. Response slowing after a side-congruent olfactory cue is interpreted as a cross-modal attentional interference effect. In addition, habituation might have led to a gradual disappearance of the cueing effect. It is concluded that under immobile conditions with passive monorhinal stimulation, humans are unable to explicitly determine the location of a pure odorant. Implicitly, however, odor localization seems to exert an influence on human behaviour. To our knowledge, these data are the first to show implicit effects of odor localization on overt human behaviour and thus support the hypothesis of residual directional smelling in humans.

  7. Is attention based on spatial contextual memory preferentially guided by low spatial frequency signals?

    Science.gov (United States)

    Patai, Eva Zita; Buckley, Alice; Nobre, Anna Christina

    2013-01-01

    A popular model of visual perception states that coarse information (carried by low spatial frequencies) along the dorsal stream is rapidly transmitted to prefrontal and medial temporal areas, activating contextual information from memory, which can in turn constrain detailed input carried by high spatial frequencies arriving at a slower rate along the ventral visual stream, thus facilitating the processing of ambiguous visual stimuli. We were interested in testing whether this model contributes to memory-guided orienting of attention. In particular, we asked whether global, low-spatial frequency (LSF) inputs play a dominant role in triggering contextual memories in order to facilitate the processing of the upcoming target stimulus. We explored this question over four experiments. The first experiment replicated the LSF advantage reported in perceptual discrimination tasks by showing that participants were faster and more accurate at matching a low spatial frequency version of a scene, compared to a high spatial frequency version, to its original counterpart in a forced-choice task. The subsequent three experiments tested the relative contributions of low versus high spatial frequencies during memory-guided covert spatial attention orienting tasks. Replicating the effects of memory-guided attention, pre-exposure to scenes associated with specific spatial memories for target locations (memory cues) led to higher perceptual discrimination and faster response times to identify targets embedded in the scenes. However, either high or low spatial frequency cues were equally effective; LSF signals did not selectively or preferentially contribute to the memory-driven attention benefits to performance. Our results challenge a generalized model that LSFs activate contextual memories, which in turn bias attention and facilitate perception.

  8. Public concerns and alternative nuclear power systems

    International Nuclear Information System (INIS)

    Mayo, L.H.

    1980-02-01

    The basic task undertaken in this study was to assess the relative public acceptability of three general types of nuclear power systems as alternatives to the existing Light Water Reactor (LWR) system. Concerns registered toward nuclear power constituted the basic data for this assessment. The primary measure adopted for determining the significance of concerns was the degree of difficulty posed by the concern to the nuclear power decisional structure in the establishment and maintenance of norms to control risks or to advance intended energy objectives. Alleviations or exacerbations of concern resulting from particular attributes of alternative systems were measured from an LWR baseline

  9. The Impact of Visual-Spatial Attention on Reading and Spelling in Chinese Children

    Science.gov (United States)

    Liu, Duo; Chen, Xi; Wang, Ying

    2016-01-01

    The present study investigated the associations of visual-spatial attention with word reading fluency and spelling in 92 third grade Hong Kong Chinese children. Word reading fluency was measured with a timed reading task whereas spelling was measured with a dictation task. Results showed that visual-spatial attention was a unique predictor of…

  10. Visuospatial Anatomy Comprehension: The Role of Spatial Visualization Ability and Problem-Solving Strategies

    Science.gov (United States)

    Nguyen, Ngan; Mulla, Ali; Nelson, Andrew J.; Wilson, Timothy D.

    2014-01-01

    The present study explored the problem-solving strategies of high- and low-spatial visualization ability learners on a novel spatial anatomy task to determine whether differences in strategies contribute to differences in task performance. The results of this study provide further insights into the processing commonalities and differences among…

  11. The Impact of Residual Vision in Spatial Skills of Individuals with Visual Impairments

    Science.gov (United States)

    Papadopoulos, Konstantinos; Koustriava, Eleni; Kartasidou, Lefkothea

    2011-01-01

    Loss of vision is believed to have a great impact on the acquisition of spatial knowledge. The aims of the present study are to examine the performance of individuals with visual impairments on spatial tasks and the impact of residual vision on processing these tasks. In all, 28 individuals with visual impairments--blindness or low…

  12. Task E container corrosion studies: Annual report

    International Nuclear Information System (INIS)

    Bunnell, L.R.; Doremus, L.A.; Topping, J.B.; Duncan, D.R.

    1994-06-01

    The Pacific Northwest Laboratory is conducting the Solid Waste Technology Support Program (SWTSP) for Westinghouse Hanford Company (WHC). Task E is the Container Corrosion Study Portion of the SWTSP that will perform testing to provide defensible data on the corrosion of low-carbon steel, as used in drums to contain chemical and radioactive wastes at the Hanford Site. A second objective of Task E is to provide and test practical alternative materials that have higher corrosion resistance than low-carbon steel. The scope of work for fiscal year (FY) 1993 included initial testing of mild steel specimens buried in Hanford soils or exposed to atmospheric corrosion in metal storage sheds. During FY 1993, progress was made in three areas of Task E. First, exposure of test materials began at the Soil Corrosion Test Site where low-carbon steel specimens were placed in the soil in five test shafts at depths of 9 m (30 ft). Second, the corrosion measurement of low-carbon steel in the soil of two solid waste trenches continued. The total exposure time is ∼ 500 days. Third, an atmospheric corrosion test of low-carbon steel was put initiated in a metal shed (Building 2401-W) in the 200 West Area. This annual report describes the Task E efforts and provides a current status

  13. The task-to-task communication between computers

    International Nuclear Information System (INIS)

    Lin Shuzi; Zhang Bingyun; Zhao Weiren

    1992-01-01

    The task-to-task communication is used in the Institute of High Energy Physics. The BES (Beijing Spectrometer) uses the communication mode to take some of the BEPC (Beijing Electron Positron Collider) running parameters needed by BES experiments in a periodic time. The authors describe the principle of transparent task-to-task communication and how to use it in BES on-line data acquisition system

  14. The Architecture of Chemical Alternatives Assessment.

    Science.gov (United States)

    Geiser, Kenneth; Tickner, Joel; Edwards, Sally; Rossi, Mark

    2015-12-01

    Chemical alternatives assessment is a method rapidly developing for use by businesses, governments, and nongovernment organizations seeking to substitute chemicals of concern in production processes and products. Chemical alternatives assessment is defined as a process for identifying, comparing, and selecting safer alternatives to chemicals of concern (including those in materials, processes, or technologies) on the basis of their hazards, performance, and economic viability. The process is intended to provide guidance for assuring that chemicals of concern are replaced with safer alternatives that are not likely to be later regretted. Conceptually, the assessment methods are developed from a set of three foundational pillars and five common principles. Based on a number of emerging alternatives assessment initiatives, in this commentary, we outline a chemical alternatives assessment blueprint structured around three broad steps: Scope, Assessment, and Selection and Implementation. Specific tasks and tools are identified for each of these three steps. While it is recognized that on-going practice will further refine and develop the method and tools, it is important that the structure of the assessment process remain flexible, adaptive, and focused on the substitution of chemicals of concern with safer alternatives. © 2015 Society for Risk Analysis.

  15. Spontaneous body movements in spatial cognition

    Directory of Open Access Journals (Sweden)

    Sergiu eTcaci Popescu

    2012-05-01

    Full Text Available People often perform spontaneous body movements during spatial tasks such as giving complex directions or orienting themselves on maps. How are these spontaneous gestures related to spatial problem-solving? We measured spontaneous movements during a perspective-taking task inspired by map reading. Analyzing the motion data to isolate rotation and translation components of motion in specific geometric relation to the task, we found out that most participants executed spontaneous miniature rotations of the head that were significantly related to the main task parameter. These head rotations were as if participants were trying to align themselves with the orientation on the map either in the image plane or on the ground plane, but with tiny amplitudes, typically below 1% of the actual movements. Our results are consistent with a model of sensorimotor prediction driving spatial reasoning. The efference copy of planned movements triggers this prediction mechanism. The movements themselves may then be mostly inhibited; the small spontaneous gestures that we measure are the visible traces of these planned but inhibited actions.

  16. Semantic elaboration in auditory and visual spatial memory.

    Science.gov (United States)

    Taevs, Meghan; Dahmani, Louisa; Zatorre, Robert J; Bohbot, Véronique D

    2010-01-01

    The aim of this study was to investigate the hypothesis that semantic information facilitates auditory and visual spatial learning and memory. An auditory spatial task was administered, whereby healthy participants were placed in the center of a semi-circle that contained an array of speakers where the locations of nameable and non-nameable sounds were learned. In the visual spatial task, locations of pictures of abstract art intermixed with nameable objects were learned by presenting these items in specific locations on a computer screen. Participants took part in both the auditory and visual spatial tasks, which were counterbalanced for order and were learned at the same rate. Results showed that learning and memory for the spatial locations of nameable sounds and pictures was significantly better than for non-nameable stimuli. Interestingly, there was a cross-modal learning effect such that the auditory task facilitated learning of the visual task and vice versa. In conclusion, our results support the hypotheses that the semantic representation of items, as well as the presentation of items in different modalities, facilitate spatial learning and memory.

  17. Spatial parameters at the basis of social transfer of learning.

    Science.gov (United States)

    Lugli, Luisa; Iani, Cristina; Milanese, Nadia; Sebanz, Natalie; Rubichi, Sandro

    2015-06-01

    Recent research indicates that practicing on a joint spatial compatibility task with an incompatible stimulus-response mapping affects subsequent joint Simon task performance, eliminating the social Simon effect. It has been well established that in individual contexts, for transfer of learning to occur, participants need to practice an incompatible association between stimulus and response positions. The mechanisms underlying transfer of learning in joint task performance are, however, less well understood. The present study was aimed at assessing the relative contribution of 3 different spatial relations characterizing the joint practice context: stimulus-response, stimulus-participant, and participant-response relations. In 3 experiments, the authors manipulated the stimulus-response, stimulus-participant, and response-participant associations. We found that learning from the practice task did not transfer to the subsequent task when during practice stimulus-response associations were spatially incompatible and stimulus-participant associations were compatible (Experiment 1). However, a transfer of learning was evident when stimulus-participant associations were spatially incompatible. This occurred both when response-participant associations were incompatible (Experiment 2) and when they were compatible (Experiment 3). These results seem to support an agent corepresentation account of correspondence effects emerging in joint settings since they suggest that, in social contexts, critical to obtain transfer-of-learning effects is the spatial relation between stimulus and participant positions while the spatial relation between stimulus and response positions is irrelevant. (c) 2015 APA, all rights reserved).

  18. Children's Task Engagement during Challenging Puzzle Tasks

    Science.gov (United States)

    Wang, Feihong; Algina, James; Snyder, Patricia; Cox, Martha

    2017-01-01

    We examined children's task engagement during a challenging puzzle task in the presence of their primary caregivers by using a representative sample of rural children from six high-poverty counties across two states. Weighted longitudinal confirmatory factor analysis and structural equation modeling were used to identify a task engagement factor…

  19. Asymmetric Spatial Processing Under Cognitive Load

    Directory of Open Access Journals (Sweden)

    Lien Naert

    2018-04-01

    Full Text Available Spatial attention allows us to selectively process information within a certain location in space. Despite the vast literature on spatial attention, the effect of cognitive load on spatial processing is still not fully understood. In this study we added cognitive load to a spatial processing task, so as to see whether it would differentially impact upon the processing of visual information in the left versus the right hemispace. The main paradigm consisted of a detection task that was performed during the maintenance interval of a verbal working memory task. We found that increasing cognitive working memory load had a more negative impact on detecting targets presented on the left side compared to those on the right side. The strength of the load effect correlated with the strength of the interaction on an individual level. The implications of an asymmetric attentional bias with a relative disadvantage for the left (vs the right hemispace under high verbal working memory (WM load are discussed.

  20. Revisiting path steering for 3D manipulation tasks

    NARCIS (Netherlands)

    L. Liu (Lei); J.-B. Martens; R. van Liere (Robert)

    2011-01-01

    htmlabstractThe law of path steering, as proposed by Accot and Zhai, describes a quantitative relationship between human temporal performance and the path spatial characteristics. The steering law is formulated as a continuous goal crossing task, in which a large number of goals are crossed along

  1. Revisiting path steering for 3D manipulation tasks

    NARCIS (Netherlands)

    L. Liu (Lei); J.-B. Martens; R. van Liere (Robert)

    2010-01-01

    htmlabstractThe law of path steering, as proposed by Accot and Zhai, describes a quantitative relationship between human temporal performance and the path spatial characteristics. The steering law is formulated as a continuous goal crossing task, in which a large number of goals are crossed along

  2. EEG source imaging assists decoding in a face recognition task

    DEFF Research Database (Denmark)

    Andersen, Rasmus S.; Eliasen, Anders U.; Pedersen, Nicolai

    2017-01-01

    of face recognition. This task concerns the differentiation of brain responses to images of faces and scrambled faces and poses a rather difficult decoding problem at the single trial level. We implement the pipeline using spatially focused features and show that this approach is challenged and source...

  3. Divided multimodal attention sensory trace and context coding strategies in spatially congruent auditory and visual presentation.

    Science.gov (United States)

    Kristjánsson, Tómas; Thorvaldsson, Tómas Páll; Kristjánsson, Arni

    2014-01-01

    Previous research involving both unimodal and multimodal studies suggests that single-response change detection is a capacity-free process while a discriminatory up or down identification is capacity-limited. The trace/context model assumes that this reflects different memory strategies rather than inherent differences between identification and detection. To perform such tasks, one of two strategies is used, a sensory trace or a context coding strategy, and if one is blocked, people will automatically use the other. A drawback to most preceding studies is that stimuli are presented at separate locations, creating the possibility of a spatial confound, which invites alternative interpretations of the results. We describe a series of experiments, investigating divided multimodal attention, without the spatial confound. The results challenge the trace/context model. Our critical experiment involved a gap before a change in volume and brightness, which according to the trace/context model blocks the sensory trace strategy, simultaneously with a roaming pedestal, which should block the context coding strategy. The results clearly show that people can use strategies other than sensory trace and context coding in the tasks and conditions of these experiments, necessitating changes to the trace/context model.

  4. Manual lateralization in macaques: handedness, target laterality and task complexity.

    Science.gov (United States)

    Regaiolli, Barbara; Spiezio, Caterina; Vallortigara, Giorgio

    2016-01-01

    Non-human primates represent models to understand the evolution of handedness in humans. Despite several researches have been investigating non-human primates handedness, few studies examined the relationship between target position, hand preference and task complexity. This study aimed at investigating macaque handedness in relation to target laterality and tastiness, as well as task complexity. Seven pig-tailed macaques (Macaca nemestrina) were involved in three different "two alternative choice" tests: one low-level task and two high-level tasks (HLTs). During the first and the third tests macaques could select a preferred food and a non-preferred food, whereas by modifying the design of the second test, macaques were presented with no-difference alternative per trial. Furthermore, a simple-reaching test was administered to assess hand preference in a social context. Macaques showed hand preference at individual level both in simple and complex tasks, but not in the simple-reaching test. Moreover, target position seemed to affect hand preference in retrieving an object in the low-level task, but not in the HLT. Additionally, individual hand preference seemed to be affected from the tastiness of the item to be retrieved. The results suggest that both target laterality and individual motivation might influence hand preference of macaques, especially in simple tasks.

  5. Linguistic and Perceptual Mapping in Spatial Representations: An Attentional Account.

    Science.gov (United States)

    Valdés-Conroy, Berenice; Hinojosa, José A; Román, Francisco J; Romero-Ferreiro, Verónica

    2018-03-01

    Building on evidence for embodied representations, we investigated whether Spanish spatial terms map onto the NEAR/FAR perceptual division of space. Using a long horizontal display, we measured congruency effects during the processing of spatial terms presented in NEAR or FAR space. Across three experiments, we manipulated the task demands in order to investigate the role of endogenous attention in linguistic and perceptual space mapping. We predicted congruency effects only when spatial properties were relevant for the task (reaching estimation task, Experiment 1) but not when attention was allocated to other features (lexical decision, Experiment 2; and color, Experiment 3). Results showed faster responses for words presented in Near-space in all experiments. Consistent with our hypothesis, congruency effects were observed only when a reaching estimate was requested. Our results add important evidence for the role of top-down processing in congruency effects from embodied representations of spatial terms. Copyright © 2017 Cognitive Science Society, Inc.

  6. Spatial and temporal characteristics of V1 microstimulation during chronic implantation of a microelectrode array in a behaving macaque

    Science.gov (United States)

    Davis, T. S.; Parker, R. A.; House, P. A.; Bagley, E.; Wendelken, S.; Normann, R. A.; Greger, B.

    2012-12-01

    Objective. It has been hypothesized that a vision prosthesis capable of evoking useful visual percepts can be based upon electrically stimulating the primary visual cortex (V1) of a blind human subject via penetrating microelectrode arrays. As a continuation of earlier work, we examined several spatial and temporal characteristics of V1 microstimulation. Approach. An array of 100 penetrating microelectrodes was chronically implanted in V1 of a behaving macaque monkey. Microstimulation thresholds were measured using a two-alternative forced choice detection task. Relative locations of electrically-evoked percepts were measured using a memory saccade-to-target task. Main results. The principal finding was that two years after implantation we were able to evoke behavioural responses to electric stimulation across the spatial extent of the array using groups of contiguous electrodes. Consistent responses to stimulation were evoked at an average threshold current per electrode of 204 ± 49 µA (mean ± std) for groups of four electrodes and 91 ± 25 µA for groups of nine electrodes. Saccades to electrically-evoked percepts using groups of nine electrodes showed that the animal could discriminate spatially distinct percepts with groups having an average separation of 1.6 ± 0.3 mm (mean ± std) in cortex and 1.0° ± 0.2° in visual space. Significance. These results demonstrate chronic perceptual functionality and provide evidence for the feasibility of a cortically-based vision prosthesis for the blind using penetrating microelectrodes.

  7. Pair Negotiation When Developing English Speaking Tasks

    Directory of Open Access Journals (Sweden)

    Ingrid Liliana Bohórquez Suárez

    2011-12-01

    Full Text Available This study analyzes what characterizes the negotiations of seventh graders at a public school in Bogotá when working in pairs to develop speaking tasks in EFL classes. The inquiry is a descriptive case study that follows the qualitative paradigm. As a result of analyzing the data, we obtained four consecutive steps that characterize students’ negotiations: Establishing a connection with a partner to work with, proposing practical alternatives, refusing mates’ propositions, and making practical decisions. Moreover, we found that the constant performance of the process of negotiation provokes students to construct a sociolinguistic identity that allows agreements to emerge.

  8. Task switching costs in preschool children and adults.

    Science.gov (United States)

    Peng, Anna; Kirkham, Natasha Z; Mareschal, Denis

    2018-08-01

    Past research investigating cognitive flexibility has shown that preschool children make many perseverative errors in tasks that require switching between different sets of rules. However, this inflexibility might not necessarily hold with easier tasks. The current study investigated the developmental differences in cognitive flexibility using a task-switching procedure that compared reaction times and accuracy in 4- and 6-year-olds with those in adults. The experiment involved simple target detection tasks and was intentionally designed in a way that the stimulus and response conflicts were minimal together with a long preparation window. Global mixing costs (performance costs when multiple tasks are relevant in a context), and local switch costs (performance costs due to switching to an alternative task) are typically thought to engage endogenous control processes. If this is the case, we should observe developmental differences with both of these costs. Our results show, however, that when the accuracy was good, there were no age differences in cognitive flexibility (i.e., the ability to manage multiple tasks and to switch between tasks) between children and adults. Even though preschool children had slower reaction times and were less accurate, the mixing and switch costs associated with task switching were not reliably larger for preschool children. Preschool children did, however, show more commission errors and greater response repetition effects than adults, which may reflect differences in inhibitory control. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. Spatial Data Management

    CERN Document Server

    Mamoulis, Nikos

    2011-01-01

    Spatial database management deals with the storage, indexing, and querying of data with spatial features, such as location and geometric extent. Many applications require the efficient management of spatial data, including Geographic Information Systems, Computer Aided Design, and Location Based Services. The goal of this book is to provide the reader with an overview of spatial data management technology, with an emphasis on indexing and search techniques. It first introduces spatial data models and queries and discusses the main issues of extending a database system to support spatial data.

  10. Blink activity and task difficulty.

    Science.gov (United States)

    Tanaka, Y; Yamaoka, K

    1993-08-01

    This study investigated the relationship between task difficulty and blink activity, which includes blink rate, blink amplitude, and blink duration. Two kinds of tasks established two levels of difficulty. In Exp. 1, a mental arithmetic task was used to examine the relationship. Analysis showed that blink rate for a difficult task was significantly higher than that for an easier one. In Exp. 2, a letter-search task (hiragana Japanese alphabet) was used while the other conditions were the same as those in Exp. 1; however, the results of this experiment were not influenced by the difficulty of the task. As results indicate that blink rate is related to not only difficulty but also the nature of the task, the nature of the task is probably dependent on a mechanism in information processing. The results for blink amplitude and blink duration showed no systematic change during either experiment.

  11. Early puzzle play: a predictor of preschoolers' spatial transformation skill.

    Science.gov (United States)

    Levine, Susan C; Ratliff, Kristin R; Huttenlocher, Janellen; Cannon, Joanna

    2012-03-01

    Individual differences in spatial skill emerge prior to kindergarten entry. However, little is known about the early experiences that may contribute to these differences. The current study examined the relation between children's early puzzle play and their spatial skill. Children and parents (n = 53) were observed at home for 90 min every 4 months (6 times) between 2 and 4 years of age (26 to 46 months). When children were 4 years 6 months old, they completed a spatial task involving mental transformations of 2-dimensional shapes. Children who were observed playing with puzzles performed better on this task than those who did not, controlling for parent education, income, and overall parent word types. Moreover, among those children who played with puzzles, frequency of puzzle play predicted performance on the spatial transformation task. Although the frequency of puzzle play did not differ for boys and girls, the quality of puzzle play (a composite of puzzle difficulty, parent engagement, and parent spatial language) was higher for boys than for girls. In addition, variation in puzzle play quality predicted performance on the spatial transformation task for girls but not for boys. Implications of these findings as well as future directions for research on the role of puzzle play in the development of spatial skill are discussed. PsycINFO Database Record (c) 2012 APA, all rights reserved.

  12. Early Puzzle Play: A predictor of preschoolers’ spatial transformation skill

    Science.gov (United States)

    Levine, S.C.; Ratliff, K.R.; Huttenlocher, J.; Cannon, J.

    2011-01-01

    Individual differences in spatial skill emerge prior to kindergarten entry. However, little is known about the early experiences that may contribute to these differences. The current study examines the relation between children’s early puzzle play and their spatial skill. Children and parents (n = 53) were observed at home for 90 minutes every four months (six times) between 2 and 4 years of age (26 to 46 months). When children were 4 years 6 months old, they completed a spatial task involving mental transformations of 2D shapes. Children who were observed playing with puzzles performed better on this task than those who did not, controlling for parent education, income, and overall parent word types. Moreover, among those children who played with puzzles, frequency of puzzle play predicted performance on the spatial transformation task. Although the frequency of puzzle play did not differ for boys and girls, the quality of puzzle play (a composite of puzzle difficulty, parent engagement, and parent spatial language) was higher for boys than girls. In addition, variation in puzzle play quality predicted performance on the spatial transformation task for girls but not boys. Implications of these findings as well as future directions for research on the role of the role of puzzle play in the development of spatial skill are discussed. PMID:22040312

  13. Action compatibility in spatial knowledge developed through virtual navigation.

    Science.gov (United States)

    Wang, Qi; Taylor, Holly A; Brunyé, Tad T

    2018-01-09

    Action-compatibility effects (ACEs) arise due to incongruity between perceptuo-motor traces stored in memory and the perceptuo-motor demands of a retrieval task. Recent research has suggested that ACEs arising during spatial memory retrieval are additionally modulated by individual differences in how experienced participants are with a college campus environment. However, the extent and nature of experience with a real-world environment is difficult to assess and control, and characteristics of the retrieval task itself might modulate ACEs during spatial memory retrieval. The present study provides a more controlled and in-depth examination of how individual differences and task-based factors interact to shape ACEs when participants retrieve spatial memories. In two experiments, participants with varied video game experience learned a virtual environment and then used the computer mouse to verify spatial relationships from different perspectives. Mouse trajectories demonstrated ACEs, differing by retrieval perspective and video game experience. Videogame experts demonstrated the ACE based on learned spatial relationships during egocentric retrieval only, whereas videogame novices showed the ACE based on semantic processing of directional terms only. Specifically, gaming experts invoke perspective-specific perceptuo-motor associations to retrieve spatial knowledge, whereas non-experts are influenced by semantically based associations specific to the retrieval task. Results are discussed in the context of action-compatibility effects, the intentional weighting hypothesis, and the flexible encoding and retrieval of spatial information.

  14. Biology task group

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    The accomplishments of the task group studies over the past year are reviewed. The purposes of biological investigations, in the context of subseabed disposal, are: an evaluation of the dose to man; an estimation of effects on the ecosystem; and an estimation of the influence of organisms on and as barriers to radionuclide migration. To accomplish these ends, the task group adopted the following research goals: (1) acquire more data on biological accumulation of specific radionuclides, such as those of Tc, Np, Ra, and Sr; (2) acquire more data on transfer coefficients from sediment to organism; (3) Calculate mass transfer rates, construct simple models using them, and estimate collective dose commitment; (4) Identify specific pathways or transfer routes, determine the rates of transfer, and make dose limit calculations with simple models; (5) Calculate dose rates to and estimate irradiation effects on the biota as a result of waste emplacement, by reference to background irradiation calculations. (6) Examine the effect of the biota on altering sediment/water radionuclide exchange; (7) Consider the biological data required to address different accident scenarios; (8) Continue to provide the basic biological information for all of the above, and ensure that the system analysis model is based on the most realistic and up-to-date concepts of marine biologists; and (9) Ensure by way of free exchange of information that the data used in any model are the best currently available

  15. Intelligent spatial ecosystem modeling using parallel processors

    International Nuclear Information System (INIS)

    Maxwell, T.; Costanza, R.

    1993-01-01

    Spatial modeling of ecosystems is essential if one's modeling goals include developing a relatively realistic description of past behavior and predictions of the impacts of alternative management policies on future ecosystem behavior. Development of these models has been limited in the past by the large amount of input data required and the difficulty of even large mainframe serial computers in dealing with large spatial arrays. These two limitations have begun to erode with the increasing availability of remote sensing data and GIS systems to manipulate it, and the development of parallel computer systems which allow computation of large, complex, spatial arrays. Although many forms of dynamic spatial modeling are highly amenable to parallel processing, the primary focus in this project is on process-based landscape models. These models simulate spatial structure by first compartmentalizing the landscape into some geometric design and then describing flows within compartments and spatial processes between compartments according to location-specific algorithms. The authors are currently building and running parallel spatial models at the regional scale for the Patuxent River region in Maryland, the Everglades in Florida, and Barataria Basin in Louisiana. The authors are also planning a project to construct a series of spatially explicit linked ecological and economic simulation models aimed at assessing the long-term potential impacts of global climate change

  16. Combined lesions of hippocampus and subiculum Do not produce deficits in a nonspatial social olfactory memory task.

    Science.gov (United States)

    Burton, S; Murphy, D; Qureshi, U; Sutton, P; O'Keefe, J

    2000-07-15

    Rats transmit information to each other about which foods are safe to eat. If a rat smells a food odor on the breath of another rat, it is subsequently more likely to eat that food than an alternative. Work by Galef et al. (1988) has shown that the observer rat forms an association between two olfactory stimuli on the breath of the demonstrator rat that has eaten the food, the food odor and carbon disulphide, which is normally present in the rat breath. Bunsey and Eichenbaum (1995) claimed that the hippocampus/subicular region is required for the long-term retention of this nonspatial form of associative memory on the basis that combined lesions of the hippocampus and subiculum produced a deficit, but lesions of either structure alone did not. We report here a failure to repeat this finding. Rats w