Is there a geometric module for spatial orientation? Insights from a rodent navigation model.

PubMed

Sheynikhovich, Denis; Chavarriaga, Ricardo; Strösslin, Thomas; Arleo, Angelo; Gerstner, Wulfram

2009-07-01

Modern psychological theories of spatial cognition postulate the existence of a geometric module for reorientation. This concept is derived from experimental data showing that in rectangular arenas with distinct landmarks in the corners, disoriented rats often make diagonal errors, suggesting their preference for the geometric (arena shape) over the nongeometric (landmarks) cues. Moreover, sensitivity of hippocampal cell firing to changes in the environment layout was taken in support of the geometric module hypothesis. Using a computational model of rat navigation, the authors proposed and tested the alternative hypothesis that the influence of spatial geometry on both behavioral and neuronal levels can be explained by the properties of visual features that constitute local views of the environment. Their modeling results suggest that the pattern of diagonal errors observed in reorientation tasks can be understood by the analysis of sensory information processing that underlies the navigation strategy employed to solve the task. In particular, 2 navigation strategies were considered: (a) a place-based locale strategy that relies on a model of grid and place cells and (b) a stimulus-response taxon strategy that involves direct association of local views with action choices. The authors showed that the application of the 2 strategies in the reorientation tasks results in different patterns of diagonal errors, consistent with behavioral data. These results argue against the geometric module hypothesis by providing a simpler and biologically more plausible explanation for the related experimental data. Moreover, the same model also describes behavioral results in different types of water-maze tasks. Copyright (c) 2009 APA, all rights reserved.

Parahippocampal and retrosplenial contributions to human spatial navigation

PubMed Central

Epstein, Russell A.

2010-01-01

Spatial navigation is a core cognitive ability in humans and animals. Neuroimaging studies have identified two functionally-defined brain regions that activate during navigational tasks and also during passive viewing of navigationally-relevant stimuli such as environmental scenes: the parahippocampal place area (PPA) and the retrosplenial complex (RSC). Recent findings indicate that the PPA and RSC play distinct and complementary roles in spatial navigation, with the PPA more concerned with representation of the local visual scene and RSC more concerned with situating the scene within the broader spatial environment. These findings are a first step towards understanding the separate components of the cortical network that mediates spatial navigation in humans. PMID:18760955

Interaction Between Hippocampus and Cerebellum Crus I in Sequence-Based but not Place-Based Navigation

PubMed Central

Iglói, Kinga; Doeller, Christian F.; Paradis, Anne-Lise; Benchenane, Karim; Berthoz, Alain; Burgess, Neil; Rondi-Reig, Laure

2015-01-01

To examine the cerebellar contribution to human spatial navigation we used functional magnetic resonance imaging and virtual reality. Our findings show that the sensory-motor requirements of navigation induce activity in cerebellar lobules and cortical areas known to be involved in the motor loop and vestibular processing. By contrast, cognitive aspects of navigation mainly induce activity in a different cerebellar lobule (VIIA Crus I). Our results demonstrate a functional link between cerebellum and hippocampus in humans and identify specific functional circuits linking lobule VIIA Crus I of the cerebellum to medial parietal, medial prefrontal, and hippocampal cortices in nonmotor aspects of navigation. They further suggest that Crus I belongs to 2 nonmotor loops, involved in different strategies: place-based navigation is supported by coherent activity between left cerebellar lobule VIIA Crus I and medial parietal cortex along with right hippocampus activity, while sequence-based navigation is supported by coherent activity between right lobule VIIA Crus I, medial prefrontal cortex, and left hippocampus. These results highlight the prominent role of the human cerebellum in both motor and cognitive aspects of navigation, and specify the cortico-cerebellar circuits by which it acts depending on the requirements of the task. PMID:24947462

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

PubMed

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.

Comparing two types of navigational interfaces for Virtual Reality.

PubMed

Teixeira, Luís; Vilar, Elisângela; Duarte, Emília; Rebelo, Francisco; da Silva, Fernando Moreira

2012-01-01

Previous studies suggest significant differences between navigating virtual environments in a life-like walking manner (i.e., using treadmills or walk-in-place techniques) and virtual navigation (i.e., flying while really standing). The latter option, which usually involves hand-centric devices (e.g., joysticks), is the most common in Virtual Reality-based studies, mostly due to low costs, less space and technology demands. However, recently, new interaction devices, originally conceived for videogames have become available offering interesting potentialities for research. This study aimed to explore the potentialities of the Nintendo Wii Balance Board as a navigation interface in a Virtual Environment presented in an immersive Virtual Reality system. Comparing participants' performance while engaged in a simulated emergency egress allows determining the adequacy of such alternative navigation interface on the basis of empirical results. Forty university students participated in this study. Results show that participants were more efficient when performing navigation tasks using the Joystick than with the Balance Board. However there were no significantly differences in the behavioral compliance with exit signs. Therefore, this study suggests that, at least for tasks similar to the studied, the Balance Board have good potentiality to be used as a navigation interface for Virtual Reality systems.

Functional cross‐hemispheric shift between object‐place paired associate memory and spatial memory in the human hippocampus

PubMed Central

Lee, Choong‐Hee; Ryu, Jungwon; Lee, Sang‐Hun; Kim, Hakjin

2016-01-01

ABSTRACT The hippocampus plays critical roles in both object‐based event memory and spatial navigation, but it is largely unknown whether the left and right hippocampi play functionally equivalent roles in these cognitive domains. To examine the hemispheric symmetry of human hippocampal functions, we used an fMRI scanner to measure BOLD activity while subjects performed tasks requiring both object‐based event memory and spatial navigation in a virtual environment. Specifically, the subjects were required to form object‐place paired associate memory after visiting four buildings containing discrete objects in a virtual plus maze. The four buildings were visually identical, and the subjects used distal visual cues (i.e., scenes) to differentiate the buildings. During testing, the subjects were required to identify one of the buildings when cued with a previously associated object, and when shifted to a random place, the subject was expected to navigate to the previously chosen building. We observed that the BOLD activity foci changed from the left hippocampus to the right hippocampus as task demand changed from identifying a previously seen object (object‐cueing period) to searching for its paired‐associate place (object‐cued place recognition period). Furthermore, the efficient retrieval of object‐place paired associate memory (object‐cued place recognition period) was correlated with the BOLD response of the left hippocampus, whereas the efficient retrieval of relatively pure spatial memory (spatial memory period) was correlated with the right hippocampal BOLD response. These findings suggest that the left and right hippocampi in humans might process qualitatively different information for remembering episodic events in space. © 2016 The Authors Hippocampus Published by Wiley Periodicals, Inc. PMID:27009679

Place recognition and heading retrieval are mediated by dissociable cognitive systems in mice.

PubMed

Julian, Joshua B; Keinath, Alexander T; Muzzio, Isabel A; Epstein, Russell A

2015-05-19

A lost navigator must identify its current location and recover its facing direction to restore its bearings. We tested the idea that these two tasks--place recognition and heading retrieval--might be mediated by distinct cognitive systems in mice. Previous work has shown that numerous species, including young children and rodents, use the geometric shape of local space to regain their sense of direction after disorientation, often ignoring nongeometric cues even when they are informative. Notably, these experiments have almost always been performed in single-chamber environments in which there is no ambiguity about place identity. We examined the navigational behavior of mice in a two-chamber paradigm in which animals had to both recognize the chamber in which they were located (place recognition) and recover their facing direction within that chamber (heading retrieval). In two experiments, we found that mice used nongeometric features for place recognition, but simultaneously failed to use these same features for heading retrieval, instead relying exclusively on spatial geometry. These results suggest the existence of separate systems for place recognition and heading retrieval in mice that are differentially sensitive to geometric and nongeometric cues. We speculate that a similar cognitive architecture may underlie human navigational behavior.

Navigation through unknown and dynamic open spaces using topological notions

NASA Astrophysics Data System (ADS)

Miguel-Tomé, Sergio

2018-04-01

Until now, most algorithms used for navigation have had the purpose of directing system towards one point in space. However, humans communicate tasks by specifying spatial relations among elements or places. In addition, the environments in which humans develop their activities are extremely dynamic. The only option that allows for successful navigation in dynamic and unknown environments is making real-time decisions. Therefore, robots capable of collaborating closely with human beings must be able to make decisions based on the local information registered by the sensors and interpret and express spatial relations. Furthermore, when one person is asked to perform a task in an environment, this task is communicated given a category of goals so the person does not need to be supervised. Thus, two problems appear when one wants to create multifunctional robots: how to navigate in dynamic and unknown environments using spatial relations and how to accomplish this without supervision. In this article, a new architecture to address the two cited problems is presented, called the topological qualitative navigation architecture. In previous works, a qualitative heuristic called the heuristic of topological qualitative semantics (HTQS) has been developed to establish and identify spatial relations. However, that heuristic only allows for establishing one spatial relation with a specific object. In contrast, navigation requires a temporal sequence of goals with different objects. The new architecture attains continuous generation of goals and resolves them using HTQS. Thus, the new architecture achieves autonomous navigation in dynamic or unknown open environments.

Landmark Learning in a Navigation Task Is Not Affected by the Female Rats' Estrus Cycle

ERIC Educational Resources Information Center

Rodriguez, Clara A.; Aguilar, Raul; Chamizo, V. D.

2011-01-01

In two experiments rats were required to escape from a circular pool by swimming to an invisible platform that was located in the same place relative to one configuration of two landmarks (X and Y). The two landmarks were placed relatively far and equidistant from the hidden platform. Training could be either on consecutive days (Experiment 1) or…

Sex differences in a landmark environmental re-orientation task only during the learning phase.

PubMed

Piccardi, Laura; Bianchini, Filippo; Iasevoli, Luigi; Giannone, Gianluca; Guariglia, Cecilia

2011-10-10

Sex differences are consistently reported in human navigation. Indeed, to orient themselves during navigation women are more likely to use landmark-based strategies and men Euclidean-based strategies. The difference could be due to selective social pressure, which fosters greater spatial ability in men, or biological factors. And the great variability of the results reported in the literature could be due to the experimental setting more than real differences in ability. In this study, navigational behaviour was assessed by means of a place-learning task in which a modified version of the Morris water maze for humans was used to evaluate sex differences. In using landmarks, sex differences emerged only during the learning phase. Although the men were faster than the women in locating the target position, the differences between the sexes disappeared in delayed recall. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Conflict between place and response navigation strategies: effects on vicarious trial and error (VTE) behaviors.

PubMed

Schmidt, Brandy; Papale, Andrew; Redish, A David; Markus, Etan J

2013-02-15

Navigation can be accomplished through multiple decision-making strategies, using different information-processing computations. A well-studied dichotomy in these decision-making strategies compares hippocampal-dependent "place" and dorsal-lateral striatal-dependent "response" strategies. A place strategy depends on the ability to flexibly respond to environmental cues, while a response strategy depends on the ability to quickly recognize and react to situations with well-learned action-outcome relationships. When rats reach decision points, they sometimes pause and orient toward the potential routes of travel, a process termed vicarious trial and error (VTE). VTE co-occurs with neurophysiological information processing, including sweeps of representation ahead of the animal in the hippocampus and transient representations of reward in the ventral striatum and orbitofrontal cortex. To examine the relationship between VTE and the place/response strategy dichotomy, we analyzed data in which rats were cued to switch between place and response strategies on a plus maze. The configuration of the maze allowed for place and response strategies to work competitively or cooperatively. Animals showed increased VTE on trials entailing competition between navigational systems, linking VTE with deliberative decision-making. Even in a well-learned task, VTE was preferentially exhibited when a spatial selection was required, further linking VTE behavior with decision-making associated with hippocampal processing.

Extensive training and hippocampus or striatum lesions: effect on place and response strategies.

PubMed

Jacobson, Tara K; Gruenbaum, Benjamin F; Markus, Etan J

2012-02-01

The hippocampus has been linked to spatial navigation and the striatum to response learning. The current study focuses on how these brain regions continue to interact when an animal is very familiar with the task and the environment and must continuously switch between navigation strategies. Rats were trained to solve a plus maze using a place or a response strategy on different trials within a testing session. A room cue (illumination) was used to indicate which strategy should be used on a given trial. After extensive training, animals underwent dorsal hippocampus, dorsal lateral striatum or sham lesions. As expected hippocampal lesions predominantly caused impairment on place but not response trials. Striatal lesions increased errors on both place and response trials. Competition between systems was assessed by determining error type. Pre-lesion and sham animals primarily made errors to arms associated with the wrong (alternative) strategy, this was not found after lesions. The data suggest a qualitative change in the relationship between hippocampal and striatal systems as a task is well learned. During acquisition the two systems work in parallel, competing with each other. After task acquisition, the two systems become more integrated and interdependent. The fact that with extensive training (as something becomes a "habit"), behaviors become dependent upon the dorsal lateral striatum has been previously shown. The current findings indicate that dorsal lateral striatum involvement occurs even when the behavior is spatial and continues to require hippocampal processing. Published by Elsevier Inc.

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

PubMed

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.

Coordinated prefrontal-hippocampal activity and navigation strategy-related prefrontal firing during spatial memory formation.

PubMed

Negrón-Oyarzo, Ignacio; Espinosa, Nelson; Aguilar, Marcelo; Fuenzalida, Marco; Aboitiz, Francisco; Fuentealba, Pablo

2018-06-18

Learning the location of relevant places in the environment is crucial for survival. Such capacity is supported by a distributed network comprising the prefrontal cortex and hippocampus, yet it is not fully understood how these structures cooperate during spatial reference memory formation. Hence, we examined neural activity in the prefrontal-hippocampal circuit in mice during acquisition of spatial reference memory. We found that interregional oscillatory coupling increased with learning, specifically in the slow-gamma frequency (20 to 40 Hz) band during spatial navigation. In addition, mice used both spatial and nonspatial strategies to navigate and solve the task, yet prefrontal neuronal spiking and oscillatory phase coupling were selectively enhanced in the spatial navigation strategy. Lastly, a representation of the behavioral goal emerged in prefrontal spiking patterns exclusively in the spatial navigation strategy. These results suggest that reference memory formation is supported by enhanced cortical connectivity and evolving prefrontal spiking representations of behavioral goals.

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

PubMed

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.

Lesions of the hippocampus or dorsolateral striatum disrupt distinct aspects of spatial navigation strategies based on proximal and distal information in a cued variant of the Morris water task

PubMed Central

Rice, James P.; Wallace, Douglas G.; Hamilton, Derek A.

2015-01-01

The hippocampus and dorsolateral striatum are critically involved in spatial navigation based on extra-maze and intra-maze cues, respectively. Previous reports from our laboratory suggest that behavior in the Morris water task may be guided by both cue types, and rats appear to switch from extra-pool to intra-pool cues to guide navigation in a sequential manner within a given trial. In two experiments, rats with hippocampal or dorsolateral striatal lesions were trained and tested in water task paradigms that involved translation and removal of a cued platform within the pool and translations of the pool itself with respect to the extra-pool cue reference frame. In the first experiment, moment-to-moment analyses of swim behavior indicate that hippocampal lesions disrupt initial trajectories based on extra-pool cues at the beginning of the trial, while dorsolateral striatal lesions disrupt subsequent swim trajectories based on the location of the cued platform at the end of the trial. In the second experiment lesions of the hippocampus, but not the dorsolateral striatum, impaired directional responding in situations where the pool was shifted within the extra-pool cue array. These results are important for understanding the cooperative interactions between the hippocampus and dorsolateral striatum in spatial learning and memory, and establish that these brain areas are continuously involved in goal-directed spatial navigation. These results also highlight the importance of the hippocampus in directional responding in addition to place navigation. PMID:25907746

What Makes Patient Navigation Most Effective: Defining Useful Tasks and Networks.

PubMed

Gunn, Christine; Battaglia, Tracy A; Parker, Victoria A; Clark, Jack A; Paskett, Electra D; Calhoun, Elizabeth; Snyder, Frederick R; Bergling, Emily; Freund, Karen M

2017-01-01

Given the momentum in adopting patient navigation into cancer care, there is a need to understand the contribution of specific navigator activities to improved clinical outcomes. A mixed-methods study combined direct observations of patient navigators within the Patient Navigation Research Program and outcome data from the trial. We correlated the frequency of navigator tasks with the outcome of rate of diagnostic resolution within 365 days among patients who received the intervention relative to controls. A focused content analysis examined those tasks with the strongest correlations between navigator tasks and patient outcomes. Navigating directly with specific patients (r = 0.679), working with clinical providers to facilitate patient care (r = 0.643), and performing tasks not directly related to their diagnostic evaluation for patients were positively associated with more timely diagnosis (r = 0.714). Using medical records for non-navigation tasks had a negative association (r = -0.643). Content analysis revealed service provision directed at specific patients improved care while systems-focused activities did not.

That's Infotainment!: How to Create Your Own Screencasts

ERIC Educational Resources Information Center

Kroski, Ellyssa

2009-01-01

Screencasts are videos that record the actions that take place on the computer screen, most often including a narrative audio track, in order to demonstrate various computer-related tasks, such as how to use a software program or navigate a certain Web site. All that is needed is a standard microphone and screen recording software, which can be…

Directional learning, but no spatial mapping by rats performing a navigational task in an inverted orientation

PubMed Central

Valerio, Stephane; Clark, Benjamin J.; Chan, Jeremy H. M.; Frost, Carlton P.; Harris, Mark J.; Taube, Jeffrey S.

2010-01-01

Previous studies have identified neurons throughout the rat limbic system that fire as a function of the animal's head direction (HD). This HD signal is particularly robust when rats locomote in the horizontal and vertical planes, but is severely attenuated when locomoting upside-down (Calton & Taube, 2005). Given the hypothesis that the HD signal represents an animal's sense of its directional heading, we evaluated whether rats could accurately navigate in an inverted (upside-down) orientation. The task required the animals to find an escape hole while locomoting inverted on a circular platform suspended from the ceiling. In experiment 1, Long-Evans rats were trained to navigate to the escape hole by locomoting from either one or four start points. Interestingly, no animals from the 4-start point group reached criterion, even after 30 days of training. Animals in the 1-start point group reached criterion after about 6 training sessions. In Experiment 2, probe tests revealed that animals navigating from either 1- or 2-start points utilized distal visual landmarks for accurate orientation. However, subsequent probe tests revealed that their performance was markedly attenuated when required to navigate to the escape hole from a novel starting point. This absence of flexibility while navigating upside-down was confirmed in experiment 3 where we show that the rats do not learn to reach a place, but instead learn separate trajectories to the target hole(s). Based on these results we argue that inverted navigation primarily involves a simple directional strategy based on visual landmarks. PMID:20109566

A characterization of performance by men and women in a virtual Morris water task: a large and reliable sex difference.

PubMed

Astur, R S; Ortiz, M L; Sutherland, R J

1998-06-01

In many mammalian species, it is known that males and females differ in place learning ability. The performance by men and women is commonly reported to also differ, despite a large amount of variability and ambiguity in measuring spatial abilities. In the non-human literature, the gold standard for measuring place learning ability in mammals is the Morris water task. This task requires subjects to use the spatial arrangement of cues outside of a circular pool to swim to a hidden goal platform located in a fixed location. We used a computerized version of the Morris water task to assess whether this task will generalize into the human domain and to examine whether sex differences exist in this domain of topographical learning and memory. Across three separate experiments, varying in attempts to maximize spatial performance, we consistently found males navigate to the hidden platform better than females across a variety of measures. The effect sizes of these differences are some of the largest ever reported and are robust and replicable across experiments. These results are the first to demonstrate the effectiveness and utility of the virtual Morris water task for humans and show a robust sex difference in virtual place learning.

Cognitive load of navigating without vision when guided by virtual sound versus spatial language.

PubMed

Klatzky, Roberta L; Marston, James R; Giudice, Nicholas A; Golledge, Reginald G; Loomis, Jack M

2006-12-01

A vibrotactile N-back task was used to generate cognitive load while participants were guided along virtual paths without vision. As participants stepped in place, they moved along a virtual path of linear segments. Information was provided en route about the direction of the next turning point, by spatial language ("left," "right," or "straight") or virtual sound (i.e., the perceived azimuth of the sound indicated the target direction). The authors hypothesized that virtual sound, being processed at direct perceptual levels, would have lower load than even simple language commands, which require cognitive mediation. As predicted, whereas the guidance modes did not differ significantly in the no-load condition, participants showed shorter distance traveled and less time to complete a path when performing the N-back task while navigating with virtual sound as guidance. Virtual sound also produced better N-back performance than spatial language. By indicating the superiority of virtual sound for guidance when cognitive load is present, as is characteristic of everyday navigation, these results have implications for guidance systems for the visually impaired and others.

Cancer Patient Navigator Tasks across the Cancer Care Continuum

PubMed Central

Braun, Kathryn L.; Kagawa-Singer, Marjorie; Holden, Alan E. C.; Burhansstipanov, Linda; Tran, Jacqueline H.; Seals, Brenda F.; Corbie-Smith, Giselle; Tsark, JoAnn U.; Harjo, Lisa; Foo, Mary Anne; Ramirez, Amelie G.

2011-01-01

Cancer patient navigation (PN) programs have been shown to increase access to and utilization of cancer care for poor and underserved individuals. Despite mounting evidence of its value, cancer patient navigation is not universally understood or provided. We describe five PN programs and the range of tasks their navigators provide across the cancer care continuum (education and outreach, screening, diagnosis and staging, treatment, survivorship, and end-of-life). Tasks are organized by their potential to make cancer services understandable, available, accessible, affordable, appropriate, and accountable. Although navigators perform similar tasks across the five programs, their specific approaches reflect differences in community culture, context, program setting, and funding. Task lists can inform the development of programs, job descriptions, training, and evaluation. They also may be useful in the move to certify navigators and establish mechanisms for reimbursement for navigation services. PMID:22423178

Simultaneous cellular-resolution optical perturbation and imaging of place cell firing fields

PubMed Central

Rickgauer, John Peter; Deisseroth, Karl; Tank, David W.

2015-01-01

Linking neural microcircuit function to emergent properties of the mammalian brain requires fine-scale manipulation and measurement of neural activity during behavior, where each neuron’s coding and dynamics can be characterized. We developed an optical method for simultaneous cellular-resolution stimulation and large-scale recording of neuronal activity in behaving mice. Dual-wavelength two-photon excitation allowed largely independent functional imaging with a green fluorescent calcium sensor (GCaMP3, λ = 920 ± 6 nm) and single-neuron photostimulation with a red-shifted optogenetic probe (C1V1, λ = 1,064 ± 6 nm) in neurons coexpressing the two proteins. We manipulated task-modulated activity in individual hippocampal CA1 place cells during spatial navigation in a virtual reality environment, mimicking natural place-field activity, or ‘biasing’, to reveal subthreshold dynamics. Notably, manipulating single place-cell activity also affected activity in small groups of other place cells that were active around the same time in the task, suggesting a functional role for local place cell interactions in shaping firing fields. PMID:25402854

Autonomous detection of indoor and outdoor signs

NASA Astrophysics Data System (ADS)

Holden, Steven; Snorrason, Magnus; Goodsell, Thomas; Stevens, Mark R.

2005-05-01

Most goal-oriented mobile robot tasks involve navigation to one or more known locations. This is generally done using GPS coordinates and landmarks outdoors, or wall-following and fiducial marks indoors. Such approaches ignore the rich source of navigation information that is already in place for human navigation in all man-made environments: signs. A mobile robot capable of detecting and reading arbitrary signs could be tasked using directions that are intuitive to hu-mans, and it could report its location relative to intuitive landmarks (a street corner, a person's office, etc.). Such ability would not require active marking of the environment and would be functional in the absence of GPS. In this paper we present an updated version of a system we call Sign Understanding in Support of Autonomous Navigation (SUSAN). This system relies on cues common to most signs, the presence of text, vivid color, and compact shape. By not relying on templates, SUSAN can detect a wide variety of signs: traffic signs, street signs, store-name signs, building directories, room signs, etc. In this paper we focus on the text detection capability. We present results summarizing probability of detection and false alarm rate across many scenes containing signs of very different designs and in a variety of lighting conditions.

Evaluation of a conceptual framework for predicting navigation performance in virtual reality.

PubMed

Grübel, Jascha; Thrash, Tyler; Hölscher, Christoph; Schinazi, Victor R

2017-01-01

Previous research in spatial cognition has often relied on simple spatial tasks in static environments in order to draw inferences regarding navigation performance. These tasks are typically divided into categories (e.g., egocentric or allocentric) that reflect different two-systems theories. Unfortunately, this two-systems approach has been insufficient for reliably predicting navigation performance in virtual reality (VR). In the present experiment, participants were asked to learn and navigate towards goal locations in a virtual city and then perform eight simple spatial tasks in a separate environment. These eight tasks were organised along four orthogonal dimensions (static/dynamic, perceived/remembered, egocentric/allocentric, and distance/direction). We employed confirmatory and exploratory analyses in order to assess the relationship between navigation performance and performances on these simple tasks. We provide evidence that a dynamic task (i.e., intercepting a moving object) is capable of predicting navigation performance in a familiar virtual environment better than several categories of static tasks. These results have important implications for studies on navigation in VR that tend to over-emphasise the role of spatial memory. Given that our dynamic tasks required efficient interaction with the human interface device (HID), they were more closely aligned with the perceptuomotor processes associated with locomotion than wayfinding. In the future, researchers should consider training participants on HIDs using a dynamic task prior to conducting a navigation experiment. Performances on dynamic tasks should also be assessed in order to avoid confounding skill with an HID and spatial knowledge acquisition.

Evaluation of a conceptual framework for predicting navigation performance in virtual reality

PubMed Central

Thrash, Tyler; Hölscher, Christoph; Schinazi, Victor R.

2017-01-01

Previous research in spatial cognition has often relied on simple spatial tasks in static environments in order to draw inferences regarding navigation performance. These tasks are typically divided into categories (e.g., egocentric or allocentric) that reflect different two-systems theories. Unfortunately, this two-systems approach has been insufficient for reliably predicting navigation performance in virtual reality (VR). In the present experiment, participants were asked to learn and navigate towards goal locations in a virtual city and then perform eight simple spatial tasks in a separate environment. These eight tasks were organised along four orthogonal dimensions (static/dynamic, perceived/remembered, egocentric/allocentric, and distance/direction). We employed confirmatory and exploratory analyses in order to assess the relationship between navigation performance and performances on these simple tasks. We provide evidence that a dynamic task (i.e., intercepting a moving object) is capable of predicting navigation performance in a familiar virtual environment better than several categories of static tasks. These results have important implications for studies on navigation in VR that tend to over-emphasise the role of spatial memory. Given that our dynamic tasks required efficient interaction with the human interface device (HID), they were more closely aligned with the perceptuomotor processes associated with locomotion than wayfinding. In the future, researchers should consider training participants on HIDs using a dynamic task prior to conducting a navigation experiment. Performances on dynamic tasks should also be assessed in order to avoid confounding skill with an HID and spatial knowledge acquisition. PMID:28915266

One's own country and familiar places in the mind's eye: different topological representations for navigational and non-navigational contents.

PubMed

Boccia, M; Piccardi, L; Palermo, L; Nemmi, F; Sulpizio, V; Galati, G; Guariglia, C

2014-09-05

Visual mental imagery is a process that draws on different cognitive abilities and is affected by the contents of mental images. Several studies have demonstrated that different brain areas subtend the mental imagery of navigational and non-navigational contents. Here, we set out to determine whether there are distinct representations for navigational and geographical images. Specifically, we used a Spatial Compatibility Task (SCT) to assess the mental representation of a familiar navigational space (the campus), a familiar geographical space (the map of Italy) and familiar objects (the clock). Twenty-one participants judged whether the vertical or the horizontal arrangement of items was correct. We found that distinct representational strategies were preferred to solve different categories on the SCT, namely, the horizontal perspective for the campus and the vertical perspective for the clock and the map of Italy. Furthermore, we found significant effects due to individual differences in the vividness of mental images and in preferences for verbal versus visual strategies, which selectively affect the contents of mental images. Our results suggest that imagining a familiar navigational space is somewhat different from imagining a familiar geographical space. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

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

PubMed Central

Fajnerová, Iveta; Rodriguez, Mabel; Levčík, David; Konrádová, Lucie; Mikoláš, Pavol; Brom, Cyril; Stuchlík, Aleš; Vlček, Kamil; Horáček, Jiří

2014-01-01

Objectives: 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 analog of the Morris water maze (MWM), the virtual Four Goals Navigation (vFGN) task. Methods: 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 the healthy controls in pointing and navigation accuracy. The DMP session showed impaired spatial memory in schizophrenia during the recall of spatial sequence and a similar deficit in spatial bias in the 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. The age affected spatial performance only in healthy controls. Conclusions: Despite some limitations of the study, our results correspond well with the previous studies in animal models of schizophrenia and support the decline of spatial cognition in schizophrenia, indicating the usefulness of the vFGN task in comparative research. PMID:24904329

Usability Testing of Two Ambulatory EHR Navigators.

PubMed

Hultman, Gretchen; Marquard, Jenna; Arsoniadis, Elliot; Mink, Pamela; Rizvi, Rubina; Ramer, Tim; Khairat, Saif; Fickau, Keri; Melton, Genevieve B

2016-01-01

Despite widespread electronic health record (EHR) adoption, poor EHR system usability continues to be a significant barrier to effective system use for end users. One key to addressing usability problems is to employ user testing and user-centered design. To understand if redesigning an EHR-based navigation tool with clinician input improved user performance and satisfaction. A usability evaluation was conducted to compare two versions of a redesigned ambulatory navigator. Participants completed tasks for five patient cases using the navigators, while employing a think-aloud protocol. The tasks were based on Meaningful Use (MU) requirements. The version of navigator did not affect perceived workload, and time to complete tasks was longer in the redesigned navigator. A relatively small portion of navigator content was used to complete the MU-related tasks, though navigation patterns were highly variable across participants for both navigators. Preferences for EHR navigation structures appeared to be individualized. This study demonstrates the importance of EHR usability assessments to evaluate group and individual performance of different interfaces and preferences for each design.

Short-Term Memory Maintenance of Object Locations during Active Navigation: Which Working Memory Subsystem Is Essential?

PubMed Central

Baumann, Oliver; Skilleter, Ashley J.; Mattingley, Jason B.

2011-01-01

The goal of the present study was to examine the extent to which working memory supports the maintenance of object locations during active spatial navigation. Participants were required to navigate a virtual environment and to encode the location of a target object. In the subsequent maintenance period they performed one of three secondary tasks that were designed to selectively load visual, verbal or spatial working memory subsystems. Thereafter participants re-entered the environment and navigated back to the remembered location of the target. We found that while navigation performance in participants with high navigational ability was impaired only by the spatial secondary task, navigation performance in participants with poor navigational ability was impaired equally by spatial and verbal secondary tasks. The visual secondary task had no effect on navigation performance. Our results extend current knowledge by showing that the differential engagement of working memory subsystems is determined by navigational ability. PMID:21629686

Memory modulates journey-dependent coding in the rat hippocampus

PubMed Central

Ferbinteanu, J.; Shirvalkar, P.; Shapiro, M. L.

2011-01-01

Neurons in the rat hippocampus signal current location by firing in restricted areas called place fields. During goal-directed tasks in mazes, place fields can also encode past and future positions through journey-dependent activity, which could guide hippocampus-dependent behavior and underlie other temporally extended memories, such as autobiographical recollections. The relevance of journey-dependent activity for hippocampal-dependent memory, however, is not well understood. To further investigate the relationship between hippocampal journey-dependent activity and memory we compared neural firing in rats performing two mnemonically distinct but behaviorally identical tasks in the plus maze: a hippocampus-dependent spatial navigation task, and a hippocampus-independent cue response task. While place, prospective, and retrospective coding reflected temporally extended behavioral episodes in both tasks, memory strategy altered coding differently before and after the choice point. Before the choice point, when discriminative selection of memory strategy was critical, a switch between the tasks elicited a change in a field’s coding category, so that a field that signaled current location in one task coded pending journeys in the other task. After the choice point, however, when memory strategy became irrelevant, the fields preserved coding categories across tasks, so that the same field consistently signaled either current location or the recent journeys. Additionally, on the start arm firing rates were affected at comparable levels by task and journey, while on the goal arm firing rates predominantly encoded journey. The data demonstrate a direct link between journey-dependent coding and memory, and suggest that episodes are encoded by both population and firing rate coding. PMID:21697365

Effects of age on navigation strategy.

PubMed

Rodgers, M Kirk; Sindone, Joseph A; Moffat, Scott D

2012-01-01

Age differences in navigation strategies have been demonstrated in animals, with aged animals more likely to prefer an egocentric (route) strategy and younger animals more likely to prefer an allocentric (place) strategy. Using a novel virtual Y-maze strategy assessment (vYSA), the present study demonstrated substantial age differences in strategy preference in humans. Older adults overwhelmingly preferred an egocentric strategy, while younger adults were equally distributed between egocentric and allocentric preference. A preference for allocentric strategy on the Y-maze strategy assessment was found to benefit performance on an independent assessment (virtual Morris water task) only in younger adults. These results establish baseline age differences in spatial strategies and suggest this may impact performance on other spatial navigation assessments. The results are interpreted within the framework of age differences in hippocampal structure and function. Copyright © 2012 Elsevier Inc. All rights reserved.

Framing spatial cognition: Neural representations of proximal and distal frames of reference and their roles in navigation

PubMed Central

Knierim, James J.; Hamilton, Derek A.

2011-01-01

The most common behavioral test of hippocampus-dependent, spatial learning and memory is the Morris water task, and the most commonly studied behavioral correlate of hippocampal neurons is the spatial specificity of place cells. Despite decades of intensive research, it is not completely understood how animals solve the water task and how place cells generate their spatially specific firing fields. Based on early work, it has become the accepted wisdom in the general neuroscience community that distal spatial cues are the primary sources of information used by animals to solve the water task (and similar spatial tasks) and by place cells to generate their spatial specificity. More recent research, along with earlier studies that were overshadowed by the emphasis on distal cues, put this common view into question by demonstrating primary influences of local cues and local boundaries on spatial behavior and place-cell firing. This paper first reviews the historical underpinnings of the “standard” view from a behavioral perspective, and then reviews newer results demonstrating that an animal's behavior in such spatial tasks is more strongly controlled by a local-apparatus frame of reference than by distal landmarks. The paper then reviews similar findings from the literature on the neurophysiological correlates of place cells and other spatially-correlated cells from related brain areas. A model is proposed by which distal cues primarily set the orientation of the animal's internal spatial coordinate system, via the head direction cell system, whereas local cues and apparatus boundaries primarily set the translation and scale of that coordinate system. PMID:22013211

SU-F-P-42: “To Navigate, Or Not to Navigate: HDR BT in Recurrent Spine Lesions”

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voros, L; Cohen, G; Zaider, M

Purpose: We compare the accuracy of HDR catheter placement for paraspinal lesions using O-arm CBCT imaging combined with StealthStation navigation and traditional fluoroscopically guided catheter placement. Methods: CT and MRI scans were acquired pre-treatment to outline the lesions and design treatment plans (pre-plans) to meet dosimetric constrains. The pre-planned catheter trajectories were transferred into the StealthStation Navigation system prior to the surgery. The StealthStation is an infra red (IR) optical navigation system used for guidance of surgical instruments. An intraoperative CBCT scan (O-arm) was acquired with reference IR optical fiducials anchored onto the patient and registered with the preplan imagemore » study to guide surgical instruments in relation to the patients’ anatomy and to place the brachytherapy catheters along the pre-planned trajectories. The final treatment plan was generated based on a 2nd intraoperative CBCT scan reflecting achieved implant geometry. The 2nd CBCT was later registered with the initial CT scan to compare the preplanned dwell positions with actual dwell positions (catheter placements). Similar workflow was used in placement of 8 catheters (1 patient) without navigation, but under fluoroscopy guidance in an interventional radiology suite. Results: A total of 18 catheters (3 patients) were placed using navigation assisted surgery. Average displacement of 0.66 cm (STD=0.37cm) was observed between the pre-plan source positions and actual source positions in the 3 dimensional space. This translates into an average 0.38 cm positioning error in one direction including registration errors, digitization errors, and the surgeons ability to follow the planned trajectory. In comparison, average displacement of non-navigated catheters was 0.50 cm (STD=0.22cm). Conclusion: Spinal lesion HDR brachytherapy planning is a difficult task. Catheter placement has a direct impact on target coverage and dose to critical structures. While limited to a handful of patients, our experience shows navigation and fluoroscopy guided placement yield similar results.« less

Hippocampus-dependent place learning enables spatial flexibility in C57BL6/N mice

PubMed Central

Kleinknecht, Karl R.; Bedenk, Benedikt T.; Kaltwasser, Sebastian F.; Grünecker, Barbara; Yen, Yi-Chun; Czisch, Michael; Wotjak, Carsten T.

2012-01-01

Spatial navigation is a fundamental capability necessary in everyday life to locate food, social partners, and shelter. It results from two very different strategies: (1) place learning which enables for flexible way finding and (2) response learning that leads to a more rigid “route following.” Despite the importance of knockout techniques that are only available in mice, little is known about mice' flexibility in spatial navigation tasks. Here we demonstrate for C57BL6/N mice in a water-cross maze (WCM) that only place learning enables spatial flexibility and relearning of a platform position, whereas response learning does not. This capability depends on an intact hippocampal formation, since hippocampus lesions by ibotenic acid (IA) disrupted relearning. In vivo manganese-enhanced magnetic resonance imaging revealed a volume loss of ≥60% of the hippocampus as a critical threshold for relearning impairments. In particular the changes in the left ventral hippocampus were indicative of relearning deficits. In summary, our findings establish the importance of hippocampus-dependent place learning for spatial flexibility and provide a first systematic analysis on spatial flexibility in mice. PMID:23293591

Dorsolateral striatal lesions impair navigation based on landmark-goal vectors but facilitate spatial learning based on a “cognitive map”

PubMed Central

Poulter, Steven L.; Austen, Joe M.

2015-01-01

In three experiments, the nature of the interaction between multiple memory systems in rats solving a variation of a spatial task in the water maze was investigated. Throughout training rats were able to find a submerged platform at a fixed distance and direction from an intramaze landmark by learning a landmark-goal vector. Extramaze cues were also available for standard place learning, or “cognitive mapping,” but these cues were valid only within each session, as the position of the platform moved around the pool between sessions together with the intramaze landmark. Animals could therefore learn the position of the platform by taking the consistent vector from the landmark across sessions or by rapidly encoding the new platform position on each session with reference to the extramaze cues. Excitotoxic lesions of the dorsolateral striatum impaired vector-based learning but facilitated cognitive map-based rapid place learning when the extramaze cues were relatively poor (Experiment 1) but not when they were more salient (Experiments 2 and 3). The way the lesion effects interacted with cue availability is consistent with the idea that the memory systems involved in the current navigation task are functionally cooperative yet associatively competitive in nature. PMID:25691518

Honeybees consolidate navigation memory during sleep.

PubMed

Beyaert, Lisa; Greggers, Uwe; Menzel, Randolf

2012-11-15

Sleep is known to support memory consolidation in animals, including humans. Here we ask whether consolidation of novel navigation memory in honeybees depends on sleep. Foragers were exposed to a forced navigation task in which they learned to home more efficiently from an unexpected release site by acquiring navigational memory during the successful homing flight. This task was quantified using harmonic radar tracking and applied to bees that were equipped with a radio frequency identification device (RFID). The RFID was used to record their outbound and inbound flights and continuously monitor their behavior inside the colony, including their rest during the day and sleep at night. Bees marked with the RFID behaved normally inside and outside the hive. Bees slept longer during the night following forced navigation tasks, but foraging flights of different lengths did not lead to different rest times during the day or total sleep time during the night. Sleep deprivation before the forced navigation task did not alter learning and memory acquired during the task. However, sleep deprivation during the night after forced navigation learning reduced the probability of returning successfully to the hive from the same release site. It is concluded that consolidation of novel navigation memory is facilitated by night sleep in bees.

Neural correlates of virtual route recognition in congenital blindness.

PubMed

Kupers, Ron; Chebat, Daniel R; Madsen, Kristoffer H; Paulson, Olaf B; Ptito, Maurice

2010-07-13

Despite the importance of vision for spatial navigation, blind subjects retain the ability to represent spatial information and to move independently in space to localize and reach targets. However, the neural correlates of navigation in subjects lacking vision remain elusive. We therefore used functional MRI (fMRI) to explore the cortical network underlying successful navigation in blind subjects. We first trained congenitally blind and blindfolded sighted control subjects to perform a virtual navigation task with the tongue display unit (TDU), a tactile-to-vision sensory substitution device that translates a visual image into electrotactile stimulation applied to the tongue. After training, participants repeated the navigation task during fMRI. Although both groups successfully learned to use the TDU in the virtual navigation task, the brain activation patterns showed substantial differences. Blind but not blindfolded sighted control subjects activated the parahippocampus and visual cortex during navigation, areas that are recruited during topographical learning and spatial representation in sighted subjects. When the navigation task was performed under full vision in a second group of sighted participants, the activation pattern strongly resembled the one obtained in the blind when using the TDU. This suggests that in the absence of vision, cross-modal plasticity permits the recruitment of the same cortical network used for spatial navigation tasks in sighted subjects.

Age-Related Differences and Cognitive Correlates of Self-Reported and Direct Navigation Performance: The Effect of Real and Virtual Test Conditions Manipulation

PubMed Central

Taillade, Mathieu; N'Kaoua, Bernard; Sauzéon, Hélène

2016-01-01

The present study investigated the effect of aging on direct navigation measures and self-reported ones according to the real-virtual test manipulation. Navigation (wayfinding tasks) and spatial memory (paper-pencil tasks) performances, obtained either in real-world or in virtual-laboratory test conditions, were compared between young (n = 32) and older (n = 32) adults who had self-rated their everyday navigation behavior (SBSOD scale). Real age-related differences were observed in navigation tasks as well as in paper-pencil tasks, which investigated spatial learning relative to the distinction between survey-route knowledge. The manipulation of test conditions (real vs. virtual) did not change these age-related differences, which are mostly explained by age-related decline in both spatial abilities and executive functioning (measured with neuropsychological tests). In contrast, elderly adults did not differ from young adults in their self-reporting relative to everyday navigation, suggesting some underestimation of navigation difficulties by elderly adults. Also, spatial abilities in young participants had a mediating effect on the relations between actual and self-reported navigation performance, but not for older participants. So, it is assumed that the older adults carried out the navigation task with fewer available spatial abilities compared to young adults, resulting in inaccurate self-estimates. PMID:26834666

Age-Related Differences and Cognitive Correlates of Self-Reported and Direct Navigation Performance: The Effect of Real and Virtual Test Conditions Manipulation.

PubMed

Taillade, Mathieu; N'Kaoua, Bernard; Sauzéon, Hélène

2015-01-01

The present study investigated the effect of aging on direct navigation measures and self-reported ones according to the real-virtual test manipulation. Navigation (wayfinding tasks) and spatial memory (paper-pencil tasks) performances, obtained either in real-world or in virtual-laboratory test conditions, were compared between young (n = 32) and older (n = 32) adults who had self-rated their everyday navigation behavior (SBSOD scale). Real age-related differences were observed in navigation tasks as well as in paper-pencil tasks, which investigated spatial learning relative to the distinction between survey-route knowledge. The manipulation of test conditions (real vs. virtual) did not change these age-related differences, which are mostly explained by age-related decline in both spatial abilities and executive functioning (measured with neuropsychological tests). In contrast, elderly adults did not differ from young adults in their self-reporting relative to everyday navigation, suggesting some underestimation of navigation difficulties by elderly adults. Also, spatial abilities in young participants had a mediating effect on the relations between actual and self-reported navigation performance, but not for older participants. So, it is assumed that the older adults carried out the navigation task with fewer available spatial abilities compared to young adults, resulting in inaccurate self-estimates.

Rats Fed a Diet Rich in Fats and Sugars Are Impaired in the Use of Spatial Geometry.

PubMed

Tran, Dominic M D; Westbrook, R Frederick

2015-12-01

A diet rich in fats and sugars is associated with cognitive deficits in people, and rodent models have shown that such a diet produces deficits on tasks assessing spatial learning and memory. Spatial navigation is guided by two distinct types of information: geometrical, such as distance and direction, and featural, such as luminance and pattern. To clarify the nature of diet-induced spatial impairments, we provided rats with standard chow supplemented with sugar water and a range of energy-rich foods eaten by people, and then we assessed their place- and object-recognition memory. Rats exposed to this diet performed comparably with control rats fed only chow on object recognition but worse on place recognition. This impairment on the place-recognition task was present after only a few days on the diet and persisted across tests. Critically, this spatial impairment was specific to the processing of distance and direction. © The Author(s) 2015.

Soldier-Based Assessment of a Dual-Row Tactor Display during Simultaneous Navigational and Robot-Monitoring Tasks

DTIC Science & Technology

2015-08-01

Navigational and Robot -Monitoring Tasks by Gina Pomranky-Hartnett, Linda R Elliott, Bruce JP Mortimer, Greg R Mort, Rodger A Pettitt, and Gary A...Tactor Display during Simultaneous Navigational and Robot -Monitoring Tasks by Gina Pomranky-Hartnett, Linda R Elliott, and Rodger A Pettitt...2014–31 March 2015 4. TITLE AND SUBTITLE Soldier-Based Assessment of a Dual-Row Tactor Display during Simultaneous Navigational and Robot -Monitoring

Easy rider: monkeys learn to drive a wheelchair to navigate through a complex maze.

PubMed

Etienne, Stephanie; Guthrie, Martin; Goillandeau, Michel; Nguyen, Tho Hai; Orignac, Hugues; Gross, Christian; Boraud, Thomas

2014-01-01

The neurological bases of spatial navigation are mainly investigated in rodents and seldom in primates. The few studies led on spatial navigation in both human and non-human primates are performed in virtual, not in real environments. This is mostly because of methodological difficulties inherent in conducting research on freely-moving monkeys in real world environments. There is some incertitude, however, regarding the extrapolation of rodent spatial navigation strategies to primates. Here we present an entirely new platform for investigating real spatial navigation in rhesus monkeys. We showed that monkeys can learn a pathway by using different strategies. In these experiments three monkeys learned to drive the wheelchair and to follow a specified route through a real maze. After learning the route, probe tests revealed that animals successively use three distinct navigation strategies based on i) the place of the reward, ii) the direction taken to obtain reward or iii) a cue indicating reward location. The strategy used depended of the options proposed and the duration of learning. This study reveals that monkeys, like rodents and humans, switch between different spatial navigation strategies with extended practice, implying well-conserved brain learning systems across different species. This new task with freely driving monkeys provides a good support for the electrophysiological and pharmacological investigation of spatial navigation in the real world by making possible electrophysiological and pharmacological investigations.

The Advantage of a Ureteroscopic Navigation System with Magnetic Tracking in Comparison with Simulated Fluoroscopy in a Phantom Study.

PubMed

Yoshida, Kenji; Yokomizo, Akira; Matsuda, Tadashi; Hamasaki, Tsutomu; Kondo, Yukihiro; Yamaguchi, Kunihisa; Kanayama, Hiro-Omi; Wakumoto, Yoshiaki; Horie, Shigeo; Naito, Seiji

2015-09-01

To assess whether our ureteroscopic real-time navigation system has the possibility to reduce radiation exposure and improve performance of ureteroscopic maneuvers in surgeons of various ages and experience levels. Our novel ureteroscopic navigation system used a magnetic tracking device to detect the position of the ureteroscope and display it on a three-dimensional image. We recruited 31 urologists from five institutions to perform two tasks. Task 1 consisted of finding three internal markings on the phantom calices. Task 2 consisted of identifying all calices by ureteroscopy. In both tasks, participants performed with simulated fluoroscopy first, followed by our navigation system. Accuracy rates (AR) for identification, required time (T) for completing the task, migration length (ML), and time exposed to simulated fluoroscopy were recorded. The AR, T, and ML for both tasks were significantly better with the navigation system than without it (Task 1 with simulated fluoroscopy vs with navigation: AR 87.1 % vs 98.9%, P=0.003; T 355 s vs 191 s, P<0.0001; ML 4627 mm vs 2701 mm, P<0.0001. Task 2: AR 88.2% vs 96.7%, P=0.011; T 394 s vs 333 s, P=0.027; ML 5966 mm vs 5299 mm, P=0.0006). In both tasks, the participants used the simulated fluoroscopy about 20% of the total task time. Our navigation system, while still under development, could help surgeons of all levels to achieve better performances for ureteroscopic maneuvers compared with using fluoroscopic guidance. It also has the potential to reduce radiation exposure during fluoroscopy.

The effects of biological sex and gonadal hormones on learning strategy in adult rats.

PubMed

Hawley, Wayne R; Grissom, Elin M; Barratt, Harriet E; Conrad, Taylor S; Dohanich, Gary P

2012-02-28

When learning to navigate toward a goal in a spatial environment, rodents employ distinct learning strategies that are governed by specific regions of the brain. In the early stages of learning, adult male rats prefer a hippocampus-dependent place strategy over a striatum-dependent response strategy. Alternatively, female rats exhibit a preference for a place strategy only when circulating levels of estradiol are elevated. Notably, male rodents typically perform better than females on a variety of spatial learning tasks, which are mediated by the hippocampus. However, limited research has been done to determine if the previously reported male spatial advantage corresponds with a greater reliance on a place strategy, and, if the male preference for a place strategy is impacted by removal of testicular hormones. A dual-solution water T-maze task, which can be solved by adopting either a place or a response strategy, was employed to determine the effects of biological sex and hormonal status on learning strategy. In the first experiment, male rats made more correct arm choices than female rats during training and exhibited a bias for a place strategy on a probe trial. The results of the second experiment indicated that testicular hormones modulated arm choice accuracy during training, but not the preference for a place strategy. Together, these findings suggest that the previously reported male spatial advantage is associated with a greater reliance on a place strategy, and that only performance during the training phase of a dual-solution learning task is impacted by removal of testicular hormones. Copyright © 2011 Elsevier Inc. All rights reserved.

Evaluation of the Military Functional Assessment Program: Preliminary Assessment of the Construct Validity Using an Archived Database of Clinical Data

DTIC Science & Technology

2013-08-01

RTD standards poses common scientific challenges that generalize to several classes of trauma. The essential requirements of key military occupations...Execute prepared land navigation task Engagement Skills Trainer 2000 (EST) – Weapons Qualification Zero a weapon and complete standard ...Alexandria, Virginia 22314. Orders will be expedited if placed through the librarian or other person designated to request documents from DTIC

Entorhinal-CA3 Dual-Input Control of Spike Timing in the Hippocampus by Theta-Gamma Coupling.

PubMed

Fernández-Ruiz, Antonio; Oliva, Azahara; Nagy, Gergő A; Maurer, Andrew P; Berényi, Antal; Buzsáki, György

2017-03-08

Theta-gamma phase coupling and spike timing within theta oscillations are prominent features of the hippocampus and are often related to navigation and memory. However, the mechanisms that give rise to these relationships are not well understood. Using high spatial resolution electrophysiology, we investigated the influence of CA3 and entorhinal inputs on the timing of CA1 neurons. The theta-phase preference and excitatory strength of the afferent CA3 and entorhinal inputs effectively timed the principal neuron activity, as well as regulated distinct CA1 interneuron populations in multiple tasks and behavioral states. Feedback potentiation of distal dendritic inhibition by CA1 place cells attenuated the excitatory entorhinal input at place field entry, coupled with feedback depression of proximal dendritic and perisomatic inhibition, allowing the CA3 input to gain control toward the exit. Thus, upstream inputs interact with local mechanisms to determine theta-phase timing of hippocampal neurons to support memory and spatial navigation. Copyright © 2017 Elsevier Inc. All rights reserved.

Navigation ability dependent neural activation in the human brain: an fMRI study.

PubMed

Ohnishi, Takashi; Matsuda, Hiroshi; Hirakata, Makiko; Ugawa, Yoshikazu

2006-08-01

Visual-spatial navigation in familiar and unfamiliar environments is an essential requirement of daily life. Animal studies indicated the importance of the hippocampus for navigation. Neuroimaging studies demonstrated gender difference or strategies dependent difference of neural substrates for navigation. Using functional magnetic resonance imaging, we measured brain activity related to navigation in four groups of normal volunteers: good navigators (males and females) and poor navigators (males and females). In a whole group analysis, task related activity was noted in the hippocampus, parahippocampal gyrus, posterior cingulate cortex, precuneus, parietal association areas, and the visual association areas. In group comparisons, good navigators showed a stronger activation in the medial temporal area and precuneus than poor navigators. There was neither sex effect nor interaction effect between sex and navigation ability. The activity in the left medial temporal areas was positively correlated with task performance, whereas activity in the right parietal area was negatively correlated with task performance. Furthermore, the activity in the bilateral medial temporal areas was positively correlated with scores reflecting preferred navigation strategies, whereas activity in the bilateral superior parietal lobules was negatively correlated with them. Our data suggest that different brain activities related to navigation should reflect navigation skill and strategies.

Design, Implementation and Evaluation of an Indoor Navigation System for Visually Impaired People

PubMed Central

Martinez-Sala, Alejandro Santos; Losilla, Fernando; Sánchez-Aarnoutse, Juan Carlos; García-Haro, Joan

2015-01-01

Indoor navigation is a challenging task for visually impaired people. Although there are guidance systems available for such purposes, they have some drawbacks that hamper their direct application in real-life situations. These systems are either too complex, inaccurate, or require very special conditions (i.e., rare in everyday life) to operate. In this regard, Ultra-Wideband (UWB) technology has been shown to be effective for indoor positioning, providing a high level of accuracy and low installation complexity. This paper presents SUGAR, an indoor navigation system for visually impaired people which uses UWB for positioning, a spatial database of the environment for pathfinding through the application of the A* algorithm, and a guidance module. The interaction with the user takes place using acoustic signals and voice commands played through headphones. The suitability of the system for indoor navigation has been verified by means of a functional and usable prototype through a field test with a blind person. In addition, other tests have been conducted in order to show the accuracy of different relevant parts of the system. PMID:26703610

Real-world navigation in amnestic mild cognitive impairment: The relation to visuospatial memory and volume of hippocampal subregions.

PubMed

Peter, Jessica; Sandkamp, Richard; Minkova, Lora; Schumacher, Lena V; Kaller, Christoph P; Abdulkadir, Ahmed; Klöppel, Stefan

2018-01-31

Spatial disorientation is a frequent symptom in Alzheimer's disease and in mild cognitive impairment (MCI). In the clinical routine, spatial orientation is less often tested with real-world navigation but rather with 2D visuoconstructive tasks. However, reports about the association between the two types of tasks are sparse. Additionally, spatial disorientation has been linked to volume of the right hippocampus but it remains unclear whether right hippocampal subregions have differential involvement in real-world navigation. Yet, this would help uncover different functional roles of the subregions, which would have important implications for understanding the neuronal underpinnings of navigation skills. We compared patients with amnestic MCI (aMCI; n = 25) and healthy elderly controls (HC; n = 25) in a real-world navigation task that engaged different spatial processes. The association between real-world navigation and different visuoconstructive tasks was tested (i.e., figures from the Consortium to Establish a Registry for Alzheimer's Disease; CERAD, the Rey-Osterrieth Complex Figure task; and clock drawing). Furthermore, the relation between spatial navigation and volume of right hippocampal subregions was examined. Linear regression and relative weight analysis were applied for statistical analyses. Patients with aMCI were significantly less able to correctly navigate through a route compared to HC but had comparable map drawing and landmark recognition skills. The association between visuoconstructive tasks and real-world navigation was only significant when using the visuospatial memory component of the Rey figure. In aMCI, more volume of the right hippocampal tail was significantly associated with better navigation skills, while volume of the right CA2/3 region was a significant predictor in HC. Standard visuoconstructive tasks (e.g., the CERAD figures or clock drawing) are not sufficient to detect real-world spatial disabilities in aMCI. Consequently, more complex visuoconstructive tasks (i.e., the Rey figure) should be routinely included in the assessment of cognitive functions in the context of AD. Moreover, in those elderly individuals with impaired complex visuospatial memory, route finding behaviour should be evaluated in detail. Regarding the contribution of hippocampal subregions to spatial navigation, the right hippocampal tail seems to be particularly important for patients with aMCI, while the CA2/3 region appears to be more relevant in HC. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluating the Ergonomics of Flexible Ureteroscopy.

PubMed

Ludwig, Wesley W; Lee, Gyusung; Ziemba, Justin B; Ko, Joan S; Matlaga, Brian R

2017-10-01

To date, the ergonomics of flexible ureteroscopy (URS) have not been well described. We performed a study to assess the biomechanical stresses on urologists performing URS and to investigate the effect of ureteroscope type on these parameters. Electromyography (EMG) was used to quantify the activation level of muscle groups involved in URS. Surface EMG electrodes (Delsys, Boston, MA) were placed on the right and left thenar, flexor carpi ulnaris (FCU), extensor carpi ulnaris (ECU), biceps, triceps, and deltoid. Three endoscopes were studied: single-use digital (Boston Scientific LithoVue), reusable digital (Karl Storz Flex-X c ), and reusable fiber-optic (Karl Storz Flex-X 2 ). Each ureteroscope was used to perform a set sequence of navigation and procedural tasks in a training model. EMG data were processed and normalized to compare the maximum voluntary contractions between muscle groups. Cumulative muscular workload (CMW) and average muscular work per second (AWS) were used for comparative analysis. For navigational tasks, CMW and AWS were greatest for the ECU, followed in descending order by right and left thenar, FCU, biceps, deltoid, and triceps. For procedural tasks, CMW and AWS were greatest for the right thenar, followed in descending order by the left thenar, ECU, FCU, triceps, biceps, and deltoid. During navigational tasks, both LithoVue and Flex-X c had lower CMWs for every muscle group than Flex-X 2 (p < 0.05). LithoVue and Flex-X c had similar AWS and both were lower than Flex-X 2 for the right thenar, ECU, biceps, and deltoid activation (p < 0.05). During procedural tasks, both LithoVue and Flex-X c had lower CMWs and AWS for right and left thenar, ECU, and biceps than Flex-X 2 (p < 0.05). This study provides the first description of EMG-measured ergonomics of URS. Both the single-use and reusable digital ureteroscopes have similar profiles, and both have significantly better ergonomic metrics than the reusable fiber-optic ureteroscope.

Immediate response strategy and shift to place strategy in submerged T-maze.

PubMed

Asem, Judith S A; Holland, Peter C

2013-12-01

A considerable amount of research has demonstrated that animals can use different strategies when learning about, and navigating within, their environment. Since the influential research of Packard and McGaugh (1996), it has been widely accepted that, early in learning, rats use a flexible dorsal hippocampal-dependent place strategy. As learning progresses, they switch to a less effortful and more automatic dorsolateral caudate-dependent response strategy. However, supporting literature is dominated by the use of appetitively motivated tasks, using food reward. Because motivation often plays a crucial role in guiding learning, memory, and behavior, we examined spatial learning strategies of rats in an escape-motivated submerged T-maze. In Experiment 1, we observed rapid learning and the opposite pattern as that reported in appetitively motivated tasks. Rats exhibited a response strategy early in learning before switching to a place strategy, which persisted over extensive training. In Experiment 2, we replicated Packard and McGaugh's (1996) observations, using the apparatus and procedures as in Experiment 1, but with food reward instead of water escape. Mechanisms for, and implications of, this motivational modulation of spatial learning strategy are considered.

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

PubMed

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.

Sex differences in visuospatial and navigational working memory: the role of mood induced by background music.

PubMed

Palmiero, Massimiliano; Nori, Raffaella; Rogolino, Carmelo; D'amico, Simonetta; Piccardi, Laura

2016-08-01

Sex differences in visuospatial abilities are long debated. Men generally outperform women, especially in wayfinding or learning a route or a sequence of places. These differences might depend on women's disadvantage in underlying spatial competences, such as mental rotation, and on the strategies used, as well as on emotions and on self-belief about navigational skills, not related to actual skill-levels. In the present study, sex differences in visuospatial and navigational working memory in emotional contexts were investigated. Participants' mood was manipulated by background music (positive, negative or neutral) while performing on the Corsi Block-tapping Task (CBT) and Walking Corsi (WalCT) test. In order to assess the effectiveness of mood manipulation, participants filled in the Positive and Negative Affect Schedule before and after carrying out the visuospatial tasks. Firstly, results showed that after mood induction, only the positive affect changed, whereas the negative affect remained unconfounded by mood and by sex. This finding is in line with the main effect of 'group' on all tests used: the positive music group scored significantly higher than other groups. Secondly, although men outperformed women in the CBT forward condition and in the WalCT forward and backward conditions, they scored higher than women only in the WalCT with the negative background music. This means that mood cannot fully explain sex differences in visuospatial and navigational working memory. Our results suggest that sex differences in the CBT and WalCT can be better explained by differences in spatial competences rather than by emotional contexts.

Enhancing Allocentric Spatial Recall in Pre-schoolers through Navigational Training Programme

PubMed Central

Boccia, Maddalena; Rosella, Michela; Vecchione, Francesca; Tanzilli, Antonio; Palermo, Liana; D'Amico, Simonetta; Guariglia, Cecilia; Piccardi, Laura

2017-01-01

Unlike for other abilities, children do not receive systematic spatial orientation training at school, even though navigational training during adulthood improves spatial skills. We investigated whether navigational training programme (NTP) improved spatial orientation skills in pre-schoolers. We administered 12-week NTP to seventeen 4- to 5-year-old children (training group, TG). The TG children and 17 age-matched children (control group, CG) who underwent standard didactics were tested twice before (T0) and after (T1) the NTP using tasks that tap into landmark, route and survey representations. We determined that the TG participants significantly improved their performances in the most demanding navigational task, which is the task that taps into survey representation. This improvement was significantly higher than that observed in the CG, suggesting that NTP fostered the acquisition of survey representation. Such representation is typically achieved by age seven. This finding suggests that NTP improves performance on higher-level navigational tasks in pre-schoolers. PMID:29085278

Seeking Information Online: The Influence of Menu Type, Navigation Path Complexity and Spatial Ability on Information Gathering Tasks

ERIC Educational Resources Information Center

Puerta Melguizo, Mari Carmen; Vidya, Uti; van Oostendorp, Herre

2012-01-01

We studied the effects of menu type, navigation path complexity and spatial ability on information retrieval performance and web disorientation or lostness. Two innovative aspects were included: (a) navigation path relevance and (b) information gathering tasks. As expected we found that, when measuring aspects directly related to navigation…

A biologically inspired meta-control navigation system for the Psikharpax rat robot.

PubMed

Caluwaerts, K; Staffa, M; N'Guyen, S; Grand, C; Dollé, L; Favre-Félix, A; Girard, B; Khamassi, M

2012-06-01

A biologically inspired navigation system for the mobile rat-like robot named Psikharpax is presented, allowing for self-localization and autonomous navigation in an initially unknown environment. The ability of parts of the model (e.g. the strategy selection mechanism) to reproduce rat behavioral data in various maze tasks has been validated before in simulations. But the capacity of the model to work on a real robot platform had not been tested. This paper presents our work on the implementation on the Psikharpax robot of two independent navigation strategies (a place-based planning strategy and a cue-guided taxon strategy) and a strategy selection meta-controller. We show how our robot can memorize which was the optimal strategy in each situation, by means of a reinforcement learning algorithm. Moreover, a context detector enables the controller to quickly adapt to changes in the environment-recognized as new contexts-and to restore previously acquired strategy preferences when a previously experienced context is recognized. This produces adaptivity closer to rat behavioral performance and constitutes a computational proposition of the role of the rat prefrontal cortex in strategy shifting. Moreover, such a brain-inspired meta-controller may provide an advancement for learning architectures in robotics.

Convergent validity and sex differences in healthy elderly adults for performance on 3D virtual reality navigation learning and 2D hidden maze tasks.

PubMed

Tippett, William J; Lee, Jang-Han; Mraz, Richard; Zakzanis, Konstantine K; Snyder, Peter J; Black, Sandra E; Graham, Simon J

2009-04-01

This study assessed the convergent validity of a virtual environment (VE) navigation learning task, the Groton Maze Learning Test (GMLT), and selected traditional neuropsychological tests performed in a group of healthy elderly adults (n = 24). The cohort was divided equally between males and females to explore performance variability due to sex differences, which were subsequently characterized and reported as part of the analysis. To facilitate performance comparisons, specific "efficiency" scores were created for both the VE navigation task and the GMLT. Men reached peak performance more rapidly than women during VE navigation and on the GMLT and significantly outperformed women on the first learning trial in the VE. Results suggest reasonable convergent validity across the VE task, GMLT, and selected neuropsychological tests for assessment of spatial memory.

Tactile Cueing as a Gravitational Substitute for Spatial Navigation During Parabolic Flight

NASA Technical Reports Server (NTRS)

Montgomery, K. L.; Beaton, K. H.; Barba, J. M.; Cackler, J. M.; Son, J. H.; Horsfield, S. P.; Wood, S. J.

2010-01-01

INTRODUCTION: Spatial navigation requires an accurate awareness of orientation in your environment. The purpose of this experiment was to examine how spatial awareness was impaired with changing gravitational cues during parabolic flight, and the extent to which vibrotactile feedback of orientation could be used to help improve performance. METHODS: Six subjects were restrained in a chair tilted relative to the plane floor, and placed at random positions during the start of the microgravity phase. Subjects reported their orientation using verbal reports, and used a hand-held controller to point to a desired target location presented using a virtual reality video mask. This task was repeated with and without constant tactile cueing of "down" direction using a belt of 8 tactors placed around the mid-torso. Control measures were obtained during ground testing using both upright and tilted conditions. RESULTS: Perceptual estimates of orientation and pointing accuracy were impaired during microgravity or during rotation about an upright axis in 1g. The amount of error was proportional to the amount of chair displacement. Perceptual errors were reduced during movement about a tilted axis on earth. CONCLUSIONS: Reduced perceptual errors during tilts in 1g indicate the importance of otolith and somatosensory cues for maintaining spatial awareness. Tactile cueing may improve navigation in operational environments or clinical populations, providing a non-visual non-auditory feedback of orientation or desired direction heading.

Dissociation between dorsal and ventral hippocampal theta oscillations during decision-making.

PubMed

Schmidt, Brandy; Hinman, James R; Jacobson, Tara K; Szkudlarek, Emily; Argraves, Melissa; Escabí, Monty A; Markus, Etan J

2013-04-03

Hippocampal theta oscillations are postulated to support mnemonic processes in humans and rodents. Theta oscillations facilitate encoding and spatial navigation, but to date, it has been difficult to dissociate the effects of volitional movement from the cognitive demands of a task. Therefore, we examined whether volitional movement or cognitive demands exerted a greater modulating factor over theta oscillations during decision-making. Given the anatomical, electrophysiological, and functional dissociations along the dorsal-ventral axis, theta oscillations were simultaneously recorded in the dorsal and ventral hippocampus in rats trained to switch between place and motor-response strategies. Stark differences in theta characteristics were found between the dorsal and ventral hippocampus in frequency, power, and coherence. Theta power increased in the dorsal, but decreased in the ventral hippocampus, during the decision-making epoch. Interestingly, the relationship between running speed and theta power was uncoupled during the decision-making epoch, a phenomenon limited to the dorsal hippocampus. Theta frequency increased in both the dorsal and ventral hippocampus during the decision epoch, although this effect was greater in the dorsal hippocampus. Despite these differences, ventral hippocampal theta was responsive to the navigation task; theta frequency, power, and coherence were all affected by cognitive demands. Theta coherence increased within the dorsal hippocampus during the decision-making epoch on all three tasks. However, coherence selectively increased throughout the hippocampus (dorsal to ventral) on the task with new hippocampal learning. Interestingly, most results were consistent across tasks, regardless of hippocampal-dependent learning. These data indicate increased integration and cooperation throughout the hippocampus during information processing.

Use of a Non-Navigational, Non-Verbal Landmark Task in Children

ERIC Educational Resources Information Center

Overman, William; Pierce, Allison; Watterson, Lucas; Coleman, Jennifer K.

2013-01-01

Two hundred and twenty two children (104 females), 1-8 years of age and young adults, were tested for up to 25 days on five versions of a non-verbal, non-navigational landmark task that had previously been used for monkeys. In monkeys, performance on this task is severely impaired following damage to the parietal cortex. For the basic task, the…

High-gamma activity in the human hippocampus and parahippocampus during inter-trial rest periods of a virtual navigation task.

PubMed

Pu, Yi; Cornwell, Brian R; Cheyne, Douglas; Johnson, Blake W

2018-05-19

In rodents, hippocampal cell assemblies formed during learning of a navigation task are observed to re-emerge during resting (offline) periods, accompanied by high-frequency oscillations (HFOs). This phenomenon is believed to reflect mechanisms for strengthening newly-formed memory traces. Using magnetoencephalography recordings and a beamforming source location algorithm (synthetic aperture magnetometry), we investigated high-gamma (80-140 Hz) oscillations in the hippocampal region in 18 human participants during inter-trial rest periods in a virtual navigation task. We found right hippocampal gamma oscillations mirrored the pattern of theta power in the same region during navigation, varying as a function of environmental novelty. Gamma power during inter-trial rest periods was positively correlated with theta power during navigation in the first task set when the environment was new and predicted greater performance improvement in the subsequent task set two where the environment became familiar. These findings provide evidence for human hippocampal reactivation accompanied by high-gamma activities immediately after learning and establish a link between hippocampal high-gamma activities and subsequent memory performance. Copyright © 2018 Elsevier Inc. All rights reserved.

Effect of physical workload and modality of information presentation on pattern recognition and navigation task performance by high-fit young males.

PubMed

Zahabi, Maryam; Zhang, Wenjuan; Pankok, Carl; Lau, Mei Ying; Shirley, James; Kaber, David

2017-11-01

Many occupations require both physical exertion and cognitive task performance. Knowledge of any interaction between physical demands and modalities of cognitive task information presentation can provide a basis for optimising performance. This study examined the effect of physical exertion and modality of information presentation on pattern recognition and navigation-related information processing. Results indicated males of equivalent high fitness, between the ages of 18 and 34, rely more on visual cues vs auditory or haptic for pattern recognition when exertion level is high. We found that navigation response time was shorter under low and medium exertion levels as compared to high intensity. Navigation accuracy was lower under high level exertion compared to medium and low levels. In general, findings indicated that use of the haptic modality for cognitive task cueing decreased accuracy in pattern recognition responses. Practitioner Summary: An examination was conducted on the effect of physical exertion and information presentation modality in pattern recognition and navigation. In occupations requiring information presentation to workers, who are simultaneously performing a physical task, the visual modality appears most effective under high level exertion while haptic cueing degrades performance.

Performance on a virtual reality angled laparoscope task correlates with spatial ability of trainees.

PubMed

Rosenthal, Rachel; Hamel, Christian; Oertli, Daniel; Demartines, Nicolas; Gantert, Walter A

2010-08-01

The aim of the present study was to investigate whether trainees' performance on a virtual reality angled laparoscope navigation task correlates with scores obtained on a validated conventional test of spatial ability. 56 participants of a surgery workshop performed an angled laparoscope navigation task on the Xitact LS 500 virtual reality Simulator. Performance parameters were correlated with the score of a validated paper-and-pencil test of spatial ability. Performance at the conventional spatial ability test significantly correlated with performance at the virtual reality task for overall task score (p < 0.001), task completion time (p < 0.001) and economy of movement (p = 0.035), not for endoscope travel speed (p = 0.947). In conclusion, trainees' performance in a standardized virtual reality camera navigation task correlates with their innate spatial ability. This VR session holds potential to serve as an assessment tool for trainees.

Vision and visual navigation in nocturnal insects.

PubMed

Warrant, Eric; Dacke, Marie

2011-01-01

With their highly sensitive visual systems, nocturnal insects have evolved a remarkable capacity to discriminate colors, orient themselves using faint celestial cues, fly unimpeded through a complicated habitat, and navigate to and from a nest using learned visual landmarks. Even though the compound eyes of nocturnal insects are significantly more sensitive to light than those of their closely related diurnal relatives, their photoreceptors absorb photons at very low rates in dim light, even during demanding nocturnal visual tasks. To explain this apparent paradox, it is hypothesized that the necessary bridge between retinal signaling and visual behavior is a neural strategy of spatial and temporal summation at a higher level in the visual system. Exactly where in the visual system this summation takes place, and the nature of the neural circuitry that is involved, is currently unknown but provides a promising avenue for future research.

Investigating virtual reality navigation in amnestic mild cognitive impairment using fMRI.

PubMed

Migo, E M; O'Daly, O; Mitterschiffthaler, M; Antonova, E; Dawson, G R; Dourish, C T; Craig, K J; Simmons, A; Wilcock, G K; McCulloch, E; Jackson, S H D; Kopelman, M D; Williams, S C R; Morris, R G

2016-01-01

Spatial navigation requires a well-established network of brain regions, including the hippocampus, caudate nucleus, and retrosplenial cortex. Amnestic Mild Cognitive Impairment (aMCI) is a condition with predominantly memory impairment, conferring a high predictive risk factor for dementia. aMCI is associated with hippocampal atrophy and subtle deficits in spatial navigation. We present the first use of a functional Magnetic Resonance Imaging (fMRI) navigation task in aMCI, using a virtual reality analog of the Radial Arm Maze. Compared with controls, aMCI patients showed reduced activity in the hippocampus bilaterally, retrosplenial cortex, and left dorsolateral prefrontal cortex. Reduced activation in key areas for successful navigation, as well as additional regions, was found alongside relatively normal task performance. Results also revealed increased activity in the right dorsolateral prefrontal cortex in aMCI patients, which may reflect compensation for reduced activations elsewhere. These data support suggestions that fMRI spatial navigation tasks may be useful for staging of progression in MCI.

Route learning in Korsakoff's syndrome: Residual acquisition of spatial memory despite profound amnesia.

PubMed

Oudman, Erik; Van der Stigchel, Stefan; Nijboer, Tanja C W; Wijnia, Jan W; Seekles, Maaike L; Postma, Albert

2016-03-01

Korsakoff's syndrome (KS) is characterized by explicit amnesia, but relatively spared implicit memory. The aim of this study was to assess to what extent KS patients can acquire spatial information while performing a spatial navigation task. Furthermore, we examined whether residual spatial acquisition in KS was based on automatic or effortful coding processes. Therefore, 20 KS patients and 20 matched healthy controls performed six tasks on spatial navigation after they navigated through a residential area. Ten participants per group were instructed to pay close attention (intentional condition), while 10 received mock instructions (incidental condition). KS patients showed hampered performance on a majority of tasks, yet their performance was superior to chance level on a route time and distance estimation tasks, a map drawing task and a route walking task. Performance was relatively spared on the route distance estimation task, but there were large variations between participants. Acquisition in KS was automatic rather than effortful, since no significant differences were obtained between the intentional and incidental condition on any task, whereas for the healthy controls, the intention to learn was beneficial for the map drawing task and the route walking task. The results of this study suggest that KS patients are still able to acquire spatial information during navigation on multiple domains despite the presence of the explicit amnesia. Residual acquisition is most likely based on automatic coding processes. © 2014 The British Psychological Society.

Neural Codes for One's Own Position and Direction in a Real-World "Vista" Environment.

PubMed

Sulpizio, Valentina; Boccia, Maddalena; Guariglia, Cecilia; Galati, Gaspare

2018-01-01

Humans, like animals, rely on an accurate knowledge of one's spatial position and facing direction to keep orientated in the surrounding space. Although previous neuroimaging studies demonstrated that scene-selective regions (the parahippocampal place area or PPA, the occipital place area or OPA and the retrosplenial complex or RSC), and the hippocampus (HC) are implicated in coding position and facing direction within small-(room-sized) and large-scale navigational environments, little is known about how these regions represent these spatial quantities in a large open-field environment. Here, we used functional magnetic resonance imaging (fMRI) in humans to explore the neural codes of these navigationally-relevant information while participants viewed images which varied for position and facing direction within a familiar, real-world circular square. We observed neural adaptation for repeated directions in the HC, even if no navigational task was required. Further, we found that the amount of knowledge of the environment interacts with the PPA selectivity in encoding positions: individuals who needed more time to memorize positions in the square during a preliminary training task showed less neural attenuation in this scene-selective region. We also observed adaptation effects, which reflect the real distances between consecutive positions, in scene-selective regions but not in the HC. When examining the multi-voxel patterns of activity we observed that scene-responsive regions and the HC encoded both spatial information and that the RSC classification accuracy for positions was higher in individuals scoring higher to a self-reported questionnaire of spatial abilities. Our findings provide new insight into how the human brain represents a real, large-scale "vista" space, demonstrating the presence of neural codes for position and direction in both scene-selective and hippocampal regions, and revealing the existence, in the former regions, of a map-like spatial representation reflecting real-world distance between consecutive positions.

Powered wheelchair simulator development: implementing combined navigation-reaching tasks with a 3D hand motion controller.

PubMed

Tao, Gordon; Archambault, Philippe S

2016-01-19

Powered wheelchair (PW) training involving combined navigation and reaching is often limited or unfeasible. Virtual reality (VR) simulators offer a feasible alternative for rehabilitation training either at home or in a clinical setting. This study evaluated a low-cost magnetic-based hand motion controller as an interface for reaching tasks within the McGill Immersive Wheelchair (miWe) simulator. Twelve experienced PW users performed three navigation-reaching tasks in the real world (RW) and in VR: working at a desk, using an elevator, and opening a door. The sense of presence in VR was assessed using the iGroup Presence Questionnaire (IPQ). We determined concordance of task performance in VR with that in the RW. A video task analysis was performed to analyse task behaviours. Compared to previous miWe data, IPQ scores were greater in the involvement domain (p < 0.05). Task analysis showed most of navigation and reaching behaviours as having moderate to excellent (K > 0.4, Cohen's Kappa) agreement between the two environments, but greater (p < 0.05) risk of collisions and reaching errors in VR. VR performance demonstrated longer (p < 0.05) task times and more discreet movements for the elevator and desk tasks but not the door task. Task performance showed poorer kinematic performance in VR than RW but similar strategies. Therefore, the reaching component represents a promising addition to the miWe training simulator, though some limitations must be addressed in future development.

Place recognition using batlike sonar.

PubMed

Vanderelst, Dieter; Steckel, Jan; Boen, Andre; Peremans, Herbert; Holderied, Marc W

2016-08-02

Echolocating bats have excellent spatial memory and are able to navigate to salient locations using bio-sonar. Navigating and route-following require animals to recognize places. Currently, it is mostly unknown how bats recognize places using echolocation. In this paper, we propose template based place recognition might underlie sonar-based navigation in bats. Under this hypothesis, bats recognize places by remembering their echo signature - rather than their 3D layout. Using a large body of ensonification data collected in three different habitats, we test the viability of this hypothesis assessing two critical properties of the proposed echo signatures: (1) they can be uniquely classified and (2) they vary continuously across space. Based on the results presented, we conclude that the proposed echo signatures satisfy both criteria. We discuss how these two properties of the echo signatures can support navigation and building a cognitive map.

Investigation of human-robot interface performance in household environments

NASA Astrophysics Data System (ADS)

Cremer, Sven; Mirza, Fahad; Tuladhar, Yathartha; Alonzo, Rommel; Hingeley, Anthony; Popa, Dan O.

2016-05-01

Today, assistive robots are being introduced into human environments at an increasing rate. Human environments are highly cluttered and dynamic, making it difficult to foresee all necessary capabilities and pre-program all desirable future skills of the robot. One approach to increase robot performance is semi-autonomous operation, allowing users to intervene and guide the robot through difficult tasks. To this end, robots need intuitive Human-Machine Interfaces (HMIs) that support fine motion control without overwhelming the operator. In this study we evaluate the performance of several interfaces that balance autonomy and teleoperation of a mobile manipulator for accomplishing several household tasks. Our proposed HMI framework includes teleoperation devices such as a tablet, as well as physical interfaces in the form of piezoresistive pressure sensor arrays. Mobile manipulation experiments were performed with a sensorized KUKA youBot, an omnidirectional platform with a 5 degrees of freedom (DOF) arm. The pick and place tasks involved navigation and manipulation of objects in household environments. Performance metrics included time for task completion and position accuracy.

The Performance Analysis of the Map-Aided Fuzzy Decision Tree Based on the Pedestrian Dead Reckoning Algorithm in an Indoor Environment

PubMed Central

Chiang, Kai-Wei; Liao, Jhen-Kai; Tsai, Guang-Je; Chang, Hsiu-Wen

2015-01-01

Hardware sensors embedded in a smartphone allow the device to become an excellent mobile navigator. A smartphone is ideal for this task because its great international popularity has led to increased phone power and since most of the necessary infrastructure is already in place. However, using a smartphone for indoor pedestrian navigation can be problematic due to the low accuracy of sensors, imprecise predictability of pedestrian motion, and inaccessibility of the Global Navigation Satellite System (GNSS) in some indoor environments. Pedestrian Dead Reckoning (PDR) is one of the most common technologies used for pedestrian navigation, but in its present form, various errors tend to accumulate. This study introduces a fuzzy decision tree (FDT) aided by map information to improve the accuracy and stability of PDR with less dependency on infrastructure. First, the map is quickly surveyed by the Indoor Mobile Mapping System (IMMS). Next, Bluetooth beacons are implemented to enable the initializing of any position. Finally, map-aided FDT can estimate navigation solutions in real time. The experiments were conducted in different fields using a variety of smartphones and users in order to verify stability. The contrast PDR system demonstrates low stability for each case without pre-calibration and post-processing, but the proposed low-complexity FDT algorithm shows good stability and accuracy under the same conditions. PMID:26729114

Similar reliability and equivalent performance of female and male mice in the open field and water‐maze place navigation task

PubMed Central

Fritz, Ann‐Kristina; Amrein, Irmgard

2017-01-01

Although most nervous system diseases affect women and men differentially, most behavioral studies using mouse models do not include subjects of both sexes. Many researchers worry that data of female mice may be unreliable due to the estrous cycle. Here, we retrospectively evaluated sex effects on coefficient of variation (CV) in 5,311 mice which had performed the same place navigation protocol in the water‐maze and in 4,554 mice tested in the same open field arena. Confidence intervals for Cohen's d as measure of effect size were computed and tested for equivalence with 0.2 as equivalence margin. Despite the large sample size, only few behavioral parameters showed a significant sex effect on CV. Confidence intervals of effect size indicated that CV was either equivalent or showed a small sex difference at most, accounting for less than 2% of total group to group variation of CV. While female mice were potentially slightly more variable in water‐maze acquisition and in the open field, males tended to perform less reliably in the water‐maze probe trial. In addition to evaluating variability, we also directly compared mean performance of female and male mice and found them to be equivalent in both water‐maze place navigation and open field exploration. Our data confirm and extend other large scale studies in demonstrating that including female mice in experiments does not cause a relevant increase of data variability. Our results make a strong case for including mice of both sexes whenever open field or water‐maze are used in preclinical research. PMID:28654717

Similar reliability and equivalent performance of female and male mice in the open field and water-maze place navigation task.

PubMed

Fritz, Ann-Kristina; Amrein, Irmgard; Wolfer, David P

2017-09-01

Although most nervous system diseases affect women and men differentially, most behavioral studies using mouse models do not include subjects of both sexes. Many researchers worry that data of female mice may be unreliable due to the estrous cycle. Here, we retrospectively evaluated sex effects on coefficient of variation (CV) in 5,311 mice which had performed the same place navigation protocol in the water-maze and in 4,554 mice tested in the same open field arena. Confidence intervals for Cohen's d as measure of effect size were computed and tested for equivalence with 0.2 as equivalence margin. Despite the large sample size, only few behavioral parameters showed a significant sex effect on CV. Confidence intervals of effect size indicated that CV was either equivalent or showed a small sex difference at most, accounting for less than 2% of total group to group variation of CV. While female mice were potentially slightly more variable in water-maze acquisition and in the open field, males tended to perform less reliably in the water-maze probe trial. In addition to evaluating variability, we also directly compared mean performance of female and male mice and found them to be equivalent in both water-maze place navigation and open field exploration. Our data confirm and extend other large scale studies in demonstrating that including female mice in experiments does not cause a relevant increase of data variability. Our results make a strong case for including mice of both sexes whenever open field or water-maze are used in preclinical research. © 2017 The Authors. American Journal of Medical Genetics Part C Published by Wiley Periodicals, Inc.

The brain-derived neurotrophic factor Val66Met polymorphism is associated with reduced functional magnetic resonance imaging activity in the hippocampus and increased use of caudate nucleus-dependent strategies in a human virtual navigation task

PubMed Central

Banner, Harrison; Bhat, Venkataramana; Etchamendy, Nicole; Joober, Ridha; Bohbot, Véronique D

2011-01-01

Multiple memory systems are involved in parallel processing of spatial information during navigation. A series of studies have distinguished between hippocampus-dependent ‘spatial’ navigation, which relies on knowledge of the relationship between landmarks in one’s environment to build a cognitive map, and habit-based ‘response’ learning, which requires the memorization of a series of actions and is mediated by the caudate nucleus. Studies have demonstrated that people spontaneously use one of these two alternative navigational strategies with almost equal frequency to solve a given navigation task, and that strategy correlates with functional magnetic resonance imaging (fMRI) activity and grey matter density. Although there is evidence for experience modulating grey matter in the hippocampus, genetic contributions may also play an important role in the hippocampus and caudate nucleus. Recently, the Val66Met polymorphism of the brain-derived neurotrophic factor (BDNF) gene has emerged as a possible inhibitor of hippocampal function. We have investigated the role of the BDNF Val66Met polymorphism on virtual navigation behaviour and brain activation during an fMRI navigation task. Our results demonstrate a genetic contribution to spontaneous strategies, where ‘Met’ carriers use a response strategy more frequently than individuals homozygous for the ‘Val’ allele. Additionally, we found increased hippocampal activation in the Val group relative to the Met group during performance of a virtual navigation task. Our results support the idea that the BDNF gene with the Val66Met polymorphism is a novel candidate gene involved in determining spontaneous strategies during navigation behaviour. PMID:21255124

Virtual/real transfer of spatial knowledge: benefit from visual fidelity provided in a virtual environment and impact of active navigation.

PubMed

Wallet, Grégory; Sauzéon, Hélène; Pala, Prashant Arvind; Larrue, Florian; Zheng, Xia; N'Kaoua, Bernard

2011-01-01

The purpose of this study was to evaluate the effect the visual fidelity of a virtual environment (VE) (undetailed vs. detailed) has on the transfer of spatial knowledge based on the navigation mode (passive vs. active) for three different spatial recall tasks (wayfinding, sketch mapping, and picture sorting). Sixty-four subjects (32 men and 32 women) participated in the experiment. Spatial learning was evaluated by these three tasks in the context of the Bordeaux district. In the wayfinding task, the results indicated that the detailed VE helped subjects to transfer their spatial knowledge from the VE to the real world, irrespective of the navigation mode. In the sketch-mapping task, the detailed VE increased performances compared to the undetailed VE condition, and allowed subjects to benefit from the active navigation. In the sorting task, performances were better in the detailed VE; however, in the undetailed version of the VE, active learning either did not help the subjects or it even deteriorated their performances. These results are discussed in terms of appropriate perceptive-motor and/or spatial representations for each spatial recall task.

Pilot performance: assessing how scan patterns & navigational assessments vary by flight expertise.

PubMed

Yang, Ji Hyun; Kennedy, Quinn; Sullivan, Joseph; Fricker, Ronald D

2013-02-01

Helicopter overland navigation is a cognitively complex task that requires continuous monitoring of system and environmental parameters and many hours of training to master. This study investigated the effect of expertise on pilots' gaze measurements, navigation accuracy, and subjective assessment of their navigation accuracy in overland navigation on easy and difficult routes. A simulated overland task was completed by 12 military officers who ranged in flight experience as measured by total flight hours (TFH). They first studied a map of a route that included both easy and difficult route sections, and then had to 'fly' this simulated route in a fixed-base helicopter simulator. They also completed pre-task estimations and post-task assessments of the navigational difficulty of the transit to each waypoint in the route. Their scan pattern was tracked via eye tracking systems, which captured both the subject's out-the-window (OTW) and topographical map scan data. TFH was not associated with navigation accuracy or root mean square (RMS) error for any route section. For the easy routes, experts spent less time scanning out the window (p = 0.61) and had shorter OTW dwell (p = -0.66). For the difficult routes, experts appeared to slow down their scan by spending as much time scanning out the window as the novices while also having fewer Map fixations (p = -0.65) and shorter OTW dwell (p = -0.69). However, TFH was not significantly correlated with more accurate estimates of route difficulty. This study found that TFH did not predict navigation accuracy or subjective assessment, but was correlated with some gaze parameters.

Spatial navigation, episodic memory, episodic future thinking, and theory of mind in children with autism spectrum disorder: evidence for impairments in mental simulation?

PubMed Central

Lind, Sophie E.; Bowler, Dermot M.; Raber, Jacob

2014-01-01

This study explored spatial navigation alongside several other cognitive abilities that are thought to share common underlying neurocognitive mechanisms (e.g., the capacity for self-projection, scene construction, or mental simulation), and which we hypothesized may be impaired in autism spectrum disorder (ASD). Twenty intellectually high-functioning children with ASD (with a mean age of ~8 years) were compared to 20 sex, age, IQ, and language ability matched typically developing children on a series of tasks to assess spatial navigation, episodic memory, episodic future thinking (also known as episodic foresight or prospection), theory of mind (ToM), relational memory, and central coherence. This is the first study to explore these abilities concurrently within the same sample. Spatial navigation was assessed using the “memory island” task, which involves finding objects within a realistic, computer simulated, three-dimensional environment. Episodic memory and episodic future thinking were assessed using a past and future event description task. ToM was assessed using the “animations” task, in which children were asked to describe the interactions between two animated triangles. Relational memory was assessed using a recognition task involving memory for items (line drawings), patterned backgrounds, or combinations of items and backgrounds. Central coherence was assessed by exploring differences in performance across segmented and unsegmented versions of block design. Children with ASD were found to show impairments in spatial navigation, episodic memory, episodic future thinking, and central coherence, but not ToM or relational memory. Among children with ASD, spatial navigation was found to be significantly negatively related to the number of repetitive behaviors. In other words, children who showed more repetitive behaviors showed poorer spatial navigation. The theoretical and practical implications of the results are discussed. PMID:25538661

Spatial navigation, episodic memory, episodic future thinking, and theory of mind in children with autism spectrum disorder: evidence for impairments in mental simulation?

PubMed

Lind, Sophie E; Bowler, Dermot M; Raber, Jacob

2014-01-01

This study explored spatial navigation alongside several other cognitive abilities that are thought to share common underlying neurocognitive mechanisms (e.g., the capacity for self-projection, scene construction, or mental simulation), and which we hypothesized may be impaired in autism spectrum disorder (ASD). Twenty intellectually high-functioning children with ASD (with a mean age of ~8 years) were compared to 20 sex, age, IQ, and language ability matched typically developing children on a series of tasks to assess spatial navigation, episodic memory, episodic future thinking (also known as episodic foresight or prospection), theory of mind (ToM), relational memory, and central coherence. This is the first study to explore these abilities concurrently within the same sample. Spatial navigation was assessed using the "memory island" task, which involves finding objects within a realistic, computer simulated, three-dimensional environment. Episodic memory and episodic future thinking were assessed using a past and future event description task. ToM was assessed using the "animations" task, in which children were asked to describe the interactions between two animated triangles. Relational memory was assessed using a recognition task involving memory for items (line drawings), patterned backgrounds, or combinations of items and backgrounds. Central coherence was assessed by exploring differences in performance across segmented and unsegmented versions of block design. Children with ASD were found to show impairments in spatial navigation, episodic memory, episodic future thinking, and central coherence, but not ToM or relational memory. Among children with ASD, spatial navigation was found to be significantly negatively related to the number of repetitive behaviors. In other words, children who showed more repetitive behaviors showed poorer spatial navigation. The theoretical and practical implications of the results are discussed.

Place recognition using batlike sonar

PubMed Central

Vanderelst, Dieter; Steckel, Jan; Boen, Andre; Peremans, Herbert; Holderied, Marc W

2016-01-01

Echolocating bats have excellent spatial memory and are able to navigate to salient locations using bio-sonar. Navigating and route-following require animals to recognize places. Currently, it is mostly unknown how bats recognize places using echolocation. In this paper, we propose template based place recognition might underlie sonar-based navigation in bats. Under this hypothesis, bats recognize places by remembering their echo signature - rather than their 3D layout. Using a large body of ensonification data collected in three different habitats, we test the viability of this hypothesis assessing two critical properties of the proposed echo signatures: (1) they can be uniquely classified and (2) they vary continuously across space. Based on the results presented, we conclude that the proposed echo signatures satisfy both criteria. We discuss how these two properties of the echo signatures can support navigation and building a cognitive map. DOI: http://dx.doi.org/10.7554/eLife.14188.001 PMID:27481189

33 CFR 72.05-1 - Purpose.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Purpose. 72.05-1 Section 72.05-1 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION MARINE... navigation maintained by or under authority of the U.S. Coast Guard, which are placed in navigable waters...

The response strategy and the place strategy in a plus-maze have different sensitivities to devaluation of expected outcome.

PubMed

Kosaki, Yutaka; Pearce, John M; McGregor, Anthony

2018-04-10

Previous studies have suggested that spatial navigation can be achieved with at least two distinct learning processes, involving either cognitive map-like representations of the local environment, referred to as the "place strategy", or simple stimulus-response (S-R) associations, the "response strategy". A similar distinction between cognitive/behavioral processes has been made in the context of non-spatial, instrumental conditioning, with the definition of two processes concerning the sensitivity of a given behavior to the expected value of its outcome as well as to the response-outcome contingency ("goal-directed action" and "S-R habit"). Here we investigated whether these two versions of dichotomist definitions of learned behavior, one spatial and the other non-spatial, correspond to each other in a formal way. Specifically, we assessed the goal-directed nature of two navigational strategies, using a combination of an outcome devaluation procedure and a spatial probe trial frequently used to dissociate the two navigational strategies. In Experiment 1, rats trained in a dual-solution T-maze task were subjected to an extinction probe trial from the opposite start arm, with or without prefeeding-induced devaluation of the expected outcome. We found that a non-significant preference for the place strategy in the non-devalued condition was completely reversed after devaluation, such that significantly more animals displayed the use of the response strategy. The result suggests that the place strategy is sensitive to the expected value of the outcome, while the response strategy is not. In Experiment 2, rats with hippocampal lesions showed significant reliance on the response strategy, regardless of whether the expected outcome was devalued or not. The result thus offers further evidence that the response strategy conforms to the definition of an outcome-insensitive, habitual form of instrumental behavior. These results together attest a formal correspondence between two types of dual-process accounts of animal learning and behavior. © 2018 The Authors Hippocampus Published by Wiley Periodicals, Inc.

Place preference and vocal learning rely on distinct reinforcers in songbirds.

PubMed

Murdoch, Don; Chen, Ruidong; Goldberg, Jesse H

2018-04-30

In reinforcement learning (RL) agents are typically tasked with maximizing a single objective function such as reward. But it remains poorly understood how agents might pursue distinct objectives at once. In machines, multiobjective RL can be achieved by dividing a single agent into multiple sub-agents, each of which is shaped by agent-specific reinforcement, but it remains unknown if animals adopt this strategy. Here we use songbirds to test if navigation and singing, two behaviors with distinct objectives, can be differentially reinforced. We demonstrate that strobe flashes aversively condition place preference but not song syllables. Brief noise bursts aversively condition song syllables but positively reinforce place preference. Thus distinct behavior-generating systems, or agencies, within a single animal can be shaped by correspondingly distinct reinforcement signals. Our findings suggest that spatially segregated vocal circuits can solve a credit assignment problem associated with multiobjective learning.

Basal Forebrain Atrophy Contributes to Allocentric Navigation Impairment in Alzheimer’s Disease Patients

PubMed Central

Kerbler, Georg M.; Nedelska, Zuzana; Fripp, Jurgen; Laczó, Jan; Vyhnalek, Martin; Lisý, Jiří; Hamlin, Adam S.; Rose, Stephen; Hort, Jakub; Coulson, Elizabeth J.

2015-01-01

The basal forebrain degenerates in Alzheimer’s disease (AD) and this process is believed to contribute to the cognitive decline observed in AD patients. Impairment in spatial navigation is an early feature of the disease but whether basal forebrain dysfunction in AD is responsible for the impaired navigation skills of AD patients is not known. Our objective was to investigate the relationship between basal forebrain volume and performance in real space as well as computer-based navigation paradigms in an elderly cohort comprising cognitively normal controls, subjects with amnestic mild cognitive impairment and those with AD. We also tested whether basal forebrain volume could predict the participants’ ability to perform allocentric- vs. egocentric-based navigation tasks. The basal forebrain volume was calculated from 1.5 T magnetic resonance imaging (MRI) scans, and navigation skills were assessed using the human analog of the Morris water maze employing allocentric, egocentric, and mixed allo/egocentric real space as well as computerized tests. When considering the entire sample, we found that basal forebrain volume correlated with spatial accuracy in allocentric (cued) and mixed allo/egocentric navigation tasks but not the egocentric (uncued) task, demonstrating an important role of the basal forebrain in mediating cue-based spatial navigation capacity. Regression analysis revealed that, although hippocampal volume reflected navigation performance across the entire sample, basal forebrain volume contributed to mixed allo/egocentric navigation performance in the AD group, whereas hippocampal volume did not. This suggests that atrophy of the basal forebrain contributes to aspects of navigation impairment in AD that are independent of hippocampal atrophy. PMID:26441643

Using virtual reality simulation to study navigation in a complex environment as a functional-cognitive task; A pilot study.

PubMed

Kizony, R; Zeilig, G; Krasovsky, T; Bondi, M; Weiss, P L; Kodesh, E; Kafri, M

2017-01-01

Navigation skills are required for performance of functional complex tasks and may decline due to aging. Investigation of navigation skills should include measurement of cognitive-executive and motor aspects, which are part of complex tasks. to compare young and older healthy adults in navigation within a simulated environment with and without a functional-cognitive task. Ten young adults (25.6±4.3 years) and seven community dwelling older men (69.9±3.8 years) were tested during a single session. After training on a self-paced treadmill to navigate in a non-functional simulation, they performed the Virtual Multiple Errands Test (VMET) in a mall simulation. Outcome measures included cognitive-executive aspects of performance and gait parameters. Younger adults' performance of the VMET was more efficient (1.8±1.0) than older adults (5.3±2.7; p < 0.05) and faster (younger 478.1±141.5 s, older 867.6±393.5 s; p < 0.05). There were no differences between groups in gait parameters. Both groups walked slower in the mall simulation. The shopping simulation provided a paradigm to assess the interplay between motor and cognitive aspects involved in the efficient performance of a complex task. The study emphasized the role of the cognitive-executive aspect of task performance in healthy older adults.

Design of a novel magnetic platform for cell manipulation

NASA Astrophysics Data System (ADS)

Lucarini, Gioia; Iacovacci, Veronica; Gouveia, Pedro J.; Ricotti, Leonardo; Menciassi, Arianna

2018-02-01

Cell manipulation tasks, especially in lab-on-a-chip applications for personalized medicine, could greatly benefit from mobile untethered microdevices able to wirelessly navigate in fluidic environments by means of magnetic fields. In this paper, the design, fabrication and testing of a magnetic platform enabling the controlled locomotion and immersion of microrobots placed at the air/liquid interface is proposed and exploited for cell manipulation. The proposed microrobot consists of a polymeric magnetic thin film that acts as cell transporter and a specific coating strategy, devised to enhance a safe cancer cell adhesion to the magnetic film. Experimental results demonstrated an overall cell viability and a fine control of magnetic microrobot locomotion. The proposed technologies are promising in view of future cell manipulation tasks for personalized medicine applications.

A Low-Cost EEG System-Based Hybrid Brain-Computer Interface for Humanoid Robot Navigation and Recognition

PubMed Central

Choi, Bongjae; Jo, Sungho

2013-01-01

This paper describes a hybrid brain-computer interface (BCI) technique that combines the P300 potential, the steady state visually evoked potential (SSVEP), and event related de-synchronization (ERD) to solve a complicated multi-task problem consisting of humanoid robot navigation and control along with object recognition using a low-cost BCI system. Our approach enables subjects to control the navigation and exploration of a humanoid robot and recognize a desired object among candidates. This study aims to demonstrate the possibility of a hybrid BCI based on a low-cost system for a realistic and complex task. It also shows that the use of a simple image processing technique, combined with BCI, can further aid in making these complex tasks simpler. An experimental scenario is proposed in which a subject remotely controls a humanoid robot in a properly sized maze. The subject sees what the surrogate robot sees through visual feedback and can navigate the surrogate robot. While navigating, the robot encounters objects located in the maze. It then recognizes if the encountered object is of interest to the subject. The subject communicates with the robot through SSVEP and ERD-based BCIs to navigate and explore with the robot, and P300-based BCI to allow the surrogate robot recognize their favorites. Using several evaluation metrics, the performances of five subjects navigating the robot were quite comparable to manual keyboard control. During object recognition mode, favorite objects were successfully selected from two to four choices. Subjects conducted humanoid navigation and recognition tasks as if they embodied the robot. Analysis of the data supports the potential usefulness of the proposed hybrid BCI system for extended applications. This work presents an important implication for the future work that a hybridization of simple BCI protocols provide extended controllability to carry out complicated tasks even with a low-cost system. PMID:24023953

A low-cost EEG system-based hybrid brain-computer interface for humanoid robot navigation and recognition.

PubMed

Choi, Bongjae; Jo, Sungho

2013-01-01

This paper describes a hybrid brain-computer interface (BCI) technique that combines the P300 potential, the steady state visually evoked potential (SSVEP), and event related de-synchronization (ERD) to solve a complicated multi-task problem consisting of humanoid robot navigation and control along with object recognition using a low-cost BCI system. Our approach enables subjects to control the navigation and exploration of a humanoid robot and recognize a desired object among candidates. This study aims to demonstrate the possibility of a hybrid BCI based on a low-cost system for a realistic and complex task. It also shows that the use of a simple image processing technique, combined with BCI, can further aid in making these complex tasks simpler. An experimental scenario is proposed in which a subject remotely controls a humanoid robot in a properly sized maze. The subject sees what the surrogate robot sees through visual feedback and can navigate the surrogate robot. While navigating, the robot encounters objects located in the maze. It then recognizes if the encountered object is of interest to the subject. The subject communicates with the robot through SSVEP and ERD-based BCIs to navigate and explore with the robot, and P300-based BCI to allow the surrogate robot recognize their favorites. Using several evaluation metrics, the performances of five subjects navigating the robot were quite comparable to manual keyboard control. During object recognition mode, favorite objects were successfully selected from two to four choices. Subjects conducted humanoid navigation and recognition tasks as if they embodied the robot. Analysis of the data supports the potential usefulness of the proposed hybrid BCI system for extended applications. This work presents an important implication for the future work that a hybridization of simple BCI protocols provide extended controllability to carry out complicated tasks even with a low-cost system.

Development of an audio-based virtual gaming environment to assist with navigation skills in the blind.

PubMed

Connors, Erin C; Yazzolino, Lindsay A; Sánchez, Jaime; Merabet, Lotfi B

2013-03-27

Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind. Using only audio based cues and set within the context of a video game metaphor, users gather relevant spatial information regarding a building's layout. This allows the user to develop an accurate spatial cognitive map of a large-scale three-dimensional space that can be manipulated for the purposes of a real indoor navigation task. After game play, participants are then assessed on their ability to navigate within the target physical building represented in the game. Preliminary results suggest that early blind users were able to acquire relevant information regarding the spatial layout of a previously unfamiliar building as indexed by their performance on a series of navigation tasks. These tasks included path finding through the virtual and physical building, as well as a series of drop off tasks. We find that the immersive and highly interactive nature of the AbES software appears to greatly engage the blind user to actively explore the virtual environment. Applications of this approach may extend to larger populations of visually impaired individuals.

Conflict between Place and Response Navigation Strategies: Effects on Vicarious Trial and Error (VTE) Behaviors

ERIC Educational Resources Information Center

Schmidt, Brandy; Papale, Andrew; Redish, A. David; Markus, Etan J.

2013-01-01

Navigation can be accomplished through multiple decision-making strategies, using different information-processing computations. A well-studied dichotomy in these decision-making strategies compares hippocampal-dependent "place" and dorsal-lateral striatal dependent "response" strategies. A place strategy depends on the ability to flexibly respond…

Sex differences on the competitive place task in the water maze: The influence of peripheral pool time on spatial navigation performance in rats.

PubMed

Devan, Bryan D; Tobin, Elizabeth L; Dunn, Emily N; Magalis, Christopher

2016-11-01

This study investigated sex differences on the competitive place version of the Morris water maze task to determine whether potential strategy differences would emerge during any phase of the study but in particular on the competitive place phase. Previous findings indicate that this version of the task is highly sensitive to measures that disrupt NMDA-dependent synaptic plasticity within the hippocampus during memory consolidation (McDonald et al., 2005). The present findings revealed significant sex differences during all phases of the study, including Phase I with standard place training to located a hidden platform/goal, Phase II mass training to a new place with the platform/goal relocated to the diagonally opposite quadrant and Phase III, competitive place probe test with the platform removed to measure spatial behaviour directed at either location. The findings showed no sex difference in escape latency and other standard performance measures during the first two phases, initial place acquisition and mass training to a new location. A very subtle male advantage in visiting both Old and New place locations during the third phase place competition test was observed, however, in the time spent swimming in the periphery of the pool, the pool wall (Zone C - outer third radial distance) was increased for females during all phases of the study, suggesting a general effect may have influenced place location search behaviour of the females. Increased peripheral pool time may represent a female preference for approaching the wall, a local cue. Alternatively, the possibility that increased peripheral swimming/thigmotaxis may represent hormonal influences interacting with strategic preferences were discussed, though no definitive conclusions about sex differences in cognitive-spatial performance or memory consolidation were inferred from the present findings. The findings suggest that mixed results reported in the literature by others may be due in part to an interaction with a persistent peripheral pool swimming response demonstrated in female rats. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

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.

The Impact of Accelerated Promotion Rates on Drill Sergeant Performance

DTIC Science & Technology

2011-01-01

land navigation, communication (voice/visual), NBC protection). I have good knowledge of most Warrior tasks; I have sufficient skills to handle...but seldom reach out on my own initiative. I communicate and work well with others regardless of background; I encourage attitudes of tolerance and...most of the Warrior tasks (e.g., land navigation, communication (voice/visual), NBC protection). I have good knowledge of most Warrior tasks; I

Influence of anatomic landmarks in the virtual environment on simulated angled laparoscope navigation

PubMed Central

Christie, Lorna S.; Goossens, Richard H. M.; de Ridder, Huib; Jakimowicz, Jack J.

2010-01-01

Background The aim of this study is to investigate the influence of the presence of anatomic landmarks on the performance of angled laparoscope navigation on the SimSurgery SEP simulator. Methods Twenty-eight experienced laparoscopic surgeons (familiar with 30° angled laparoscope, >100 basic laparoscopic procedures, >5 advanced laparoscopic procedures) and 23 novices (no laparoscopy experience) performed the Camera Navigation task in an abstract virtual environment (CN-box) and in a virtual representation of the lower abdomen (CN-abdomen). They also rated the realism and added value of the virtual environments on seven-point scales. Results Within both groups, the CN-box task was accomplished in less time and with shorter tip trajectory than the CN-abdomen task (Wilcoxon test, p < 0.05). No significant differences were found between the performances of the experienced participants and the novices on the CN tasks (Mann–Whitney U test, p > 0.05). In both groups, the CN tasks were perceived as hard work and more challenging than anticipated. Conclusions Performance of the angled laparoscope navigation task is influenced by the virtual environment surrounding the exercise. The task was performed better in an abstract environment than in a virtual environment with anatomic landmarks. More insight is required into the influence and function of different types of intrinsic and extrinsic feedback on the effectiveness of preclinical simulator training. PMID:20419318

Situationally driven local navigation for mobile robots. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Slack, Marc Glenn

1990-01-01

For mobile robots to autonomously accommodate dynamically changing navigation tasks in a goal-directed fashion, they must employ navigation plans. Any such plan must provide for the robot's immediate and continuous need for guidance while remaining highly flexible in order to avoid costly computation each time the robot's perception of the world changes. Due to the world's uncertainties, creation and maintenance of navigation plans cannot involve arbitrarily complex processes, as the robot's perception of the world will be in constant flux, requiring modifications to be made quickly if they are to be of any use. This work introduces navigation templates (NaT's) which are building blocks for the construction and maintenance of rough navigation plans which capture the relationship that objects in the world have to the current navigation task. By encoding only the critical relationship between the objects in the world and the navigation task, a NaT-based navigation plan is highly flexible; allowing new constraints to be quickly incorporated into the plan and existing constraints to be updated or deleted from the plan. To satisfy the robot's need for immediate local guidance, the NaT's forming the current navigation plan are passed to a transformation function. The transformation function analyzes the plan with respect to the robot's current location to quickly determine (a few times a second) the locally preferred direction of travel. This dissertation presents NaT's and the transformation function as well as the needed support systems to demonstrate the usefulness of the technique for controlling the actions of a mobile robot operating in an uncertain world.

The effects of pregnancy, lactation, and primiparity on object-in-place memory of female rats.

PubMed

Cost, Katherine Tombeau; Lobell, Thomas D; Williams-Yee, Zari N; Henderson, Sherryl; Dohanich, Gary

2014-01-01

Maternal physiology and behavior change dramatically over the course of pregnancy to nurture the fetus and prepare for motherhood. Further, the experience of motherhood itself continues to influence brain functioning well after birth, shaping behavior to promote the survival of offspring. To meet these goals, cognitive abilities, such as spatial memory and navigation, may be enhanced to facilitate foraging behavior. Existing studies on pregnant and maternal rats demonstrate enhanced cognitive function in specific spatial domains. We adopted a novel object-in-place task to assess the ability of female rats to integrate information about specific objects in specific locations, a critical element of foraging behavior. Using a longitudinal design to study changes in spatial memory across pregnancy and motherhood, an advantage in the object-in-place memory of primiparous female rats compared to nulliparous females emerged during lactation not during pregnancy, and was maintained after weaning at 42 days postpartum. This enhancement was not dependent on the non-mnemonic variables of anxiety or neophobia. Parity did not affect the type of learning strategy used by females to locate a cued escape platform on a dual-solution water maze task. Results indicate that the enhancement of object-in-place memory, a cognitive function that facilitates foraging, emerged after pregnancy during the postpartum period of lactation and persisted for several weeks after weaning of offspring. © 2013.

Navigating a Maze with Balance Board and Wiimote

NASA Astrophysics Data System (ADS)

Fikkert, Wim; Hoeijmakers, Niek; van der Vet, Paul; Nijholt, Anton

Input from the lower body in human-computer interfaces can be beneficial, enjoyable and even entertaining when users are expected to perform tasks simultaneously. Users can navigate a virtual (game) world or even an (empirical) dataset while having their hands free to issue commands. We compared the Wii Balance Board to a hand-held Wiimote for navigating a maze and found that users completed this task slower with the Balance Board. However, the Balance Board was considered more intuitive, easy to learn and ‘much fun’.

Spatial and temporal aspects of navigation in two neurological patients.

PubMed

van der Ham, Ineke J M; van Zandvoort, Martine J E; Meilinger, Tobias; Bosch, Sander E; Kant, Neeltje; Postma, Albert

2010-07-14

We present two cases (A.C. and W.J.) with navigation problems resulting from parieto-occipital right hemisphere damage. For both the cases, performance on the neuropsychological tests did not indicate specific impairments in spatial processing, despite severe subjective complaints of spatial disorientation. Various aspects of navigation were tested in a new virtual reality task, the Virtual Tübingen task. A double dissociation between spatial and temporal deficits was found; A.C. was impaired in route ordering, a temporal test, whereas W.J. was impaired in scene recognition and route continuation, which are spatial in nature. These findings offer important insights in the functional and neural architecture of navigation.

Natural Language Processing in aid of FlyBase curators

PubMed Central

Karamanis, Nikiforos; Seal, Ruth; Lewin, Ian; McQuilton, Peter; Vlachos, Andreas; Gasperin, Caroline; Drysdale, Rachel; Briscoe, Ted

2008-01-01

Background Despite increasing interest in applying Natural Language Processing (NLP) to biomedical text, whether this technology can facilitate tasks such as database curation remains unclear. Results PaperBrowser is the first NLP-powered interface that was developed under a user-centered approach to improve the way in which FlyBase curators navigate an article. In this paper, we first discuss how observing curators at work informed the design and evaluation of PaperBrowser. Then, we present how we appraise PaperBrowser's navigational functionalities in a user-based study using a text highlighting task and evaluation criteria of Human-Computer Interaction. Our results show that PaperBrowser reduces the amount of interactions between two highlighting events and therefore improves navigational efficiency by about 58% compared to the navigational mechanism that was previously available to the curators. Moreover, PaperBrowser is shown to provide curators with enhanced navigational utility by over 74% irrespective of the different ways in which they highlight text in the article. Conclusion We show that state-of-the-art performance in certain NLP tasks such as Named Entity Recognition and Anaphora Resolution can be combined with the navigational functionalities of PaperBrowser to support curation quite successfully. PMID:18410678

Cybersecurity for aerospace autonomous systems

NASA Astrophysics Data System (ADS)

Straub, Jeremy

2015-05-01

High profile breaches have occurred across numerous information systems. One area where attacks are particularly problematic is autonomous control systems. This paper considers the aerospace information system, focusing on elements that interact with autonomous control systems (e.g., onboard UAVs). It discusses the trust placed in the autonomous systems and supporting systems (e.g., navigational aids) and how this trust can be validated. Approaches to remotely detect the UAV compromise, without relying on the onboard software (on a potentially compromised system) as part of the process are discussed. How different levels of autonomy (task-based, goal-based, mission-based) impact this remote characterization is considered.

Computational Properties of the Hippocampus Increase the Efficiency of Goal-Directed Foraging through Hierarchical Reinforcement Learning

PubMed Central

Chalmers, Eric; Luczak, Artur; Gruber, Aaron J.

2016-01-01

The mammalian brain is thought to use a version of Model-based Reinforcement Learning (MBRL) to guide “goal-directed” behavior, wherein animals consider goals and make plans to acquire desired outcomes. However, conventional MBRL algorithms do not fully explain animals' ability to rapidly adapt to environmental changes, or learn multiple complex tasks. They also require extensive computation, suggesting that goal-directed behavior is cognitively expensive. We propose here that key features of processing in the hippocampus support a flexible MBRL mechanism for spatial navigation that is computationally efficient and can adapt quickly to change. We investigate this idea by implementing a computational MBRL framework that incorporates features inspired by computational properties of the hippocampus: a hierarchical representation of space, “forward sweeps” through future spatial trajectories, and context-driven remapping of place cells. We find that a hierarchical abstraction of space greatly reduces the computational load (mental effort) required for adaptation to changing environmental conditions, and allows efficient scaling to large problems. It also allows abstract knowledge gained at high levels to guide adaptation to new obstacles. Moreover, a context-driven remapping mechanism allows learning and memory of multiple tasks. Simulating dorsal or ventral hippocampal lesions in our computational framework qualitatively reproduces behavioral deficits observed in rodents with analogous lesions. The framework may thus embody key features of how the brain organizes model-based RL to efficiently solve navigation and other difficult tasks. PMID:28018203

Taux: A System for Evaluating Sound Feedback in Navigational Tasks

ERIC Educational Resources Information Center

Lutz, Robert J.

2008-01-01

This thesis presents the design and development of an evaluation system for generating audio displays that provide feedback to persons performing navigation tasks. It first develops the need for such a system by describing existing wayfinding solutions, investigating new electronic location-based methods that have the potential of changing these…

Design of a 3D Navigation Technique Supporting VR Interaction

NASA Astrophysics Data System (ADS)

Boudoin, Pierre; Otmane, Samir; Mallem, Malik

2008-06-01

Multimodality is a powerful paradigm to increase the realness and the easiness of the interaction in Virtual Environments (VEs). In particular, the search for new metaphors and techniques for 3D interaction adapted to the navigation task is an important stage for the realization of future 3D interaction systems that support multimodality, in order to increase efficiency and usability. In this paper we propose a new multimodal 3D interaction model called Fly Over. This model is especially devoted to the navigation task. We present a qualitative comparison between Fly Over and a classical navigation technique called gaze-directed steering. The results from preliminary evaluation on the IBISC semi-immersive Virtual Reality/Augmented Realty EVR@ platform show that Fly Over is a user friendly and efficient navigation technique.

Clinical governance--watchword or buzzword?

PubMed

Campbell, A V

2001-04-01

In the latest reform of the National Health Service great emphasis has been placed on the achievement and maintenance of quality. Mechanisms for ensuring this are being set up under the general title of "clinical governance". What is the meaning of this term? The metaphor behind the phrase is of navigation through stormy seas, but who guides the helmsman? Clinical ethics committees could have a part to play in these changes, provided their role is properly understood. Clinical governance is concerned with management according to an agreed set of aims. The task of ethics committees is Socratic rather than managerial. They should ask fundamental questions about the ethical norms of the services provided and give critical appraisal of the moral character of institutional policies. If these tasks are carried out then governance may become a watchword rather than just another buzzword.

33 CFR 64.06 - Definition of terms.

Code of Federal Regulations, 2011 CFR

2011-07-01

... placed in the water, which may interfere with or restrict marine navigation. [CGD 78-156, 48 FR 11267... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Definition of terms. 64.06 Section 64.06 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO...

33 CFR 64.06 - Definition of terms.

Code of Federal Regulations, 2010 CFR

2010-07-01

... placed in the water, which may interfere with or restrict marine navigation. [CGD 78-156, 48 FR 11267... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Definition of terms. 64.06 Section 64.06 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO...

Mental space travel: damage to posterior parietal cortex prevents egocentric navigation and reexperiencing of remote spatial memories.

PubMed

Ciaramelli, Elisa; Rosenbaum, R Shayna; Solcz, Stephanie; Levine, Brian; Moscovitch, Morris

2010-05-01

The ability to navigate in a familiar environment depends on both an intact mental representation of allocentric spatial information and the integrity of systems supporting complementary egocentric representations. Although the hippocampus has been implicated in learning new allocentric spatial information, converging evidence suggests that the posterior parietal cortex (PPC) might support egocentric representations. To date, however, few studies have examined long-standing egocentric representations of environments learned long ago. Here we tested 7 patients with focal lesions in PPC and 12 normal controls in remote spatial memory tasks, including 2 tasks reportedly reliant on allocentric representations (distance and proximity judgments) and 2 tasks reportedly reliant on egocentric representations (landmark sequencing and route navigation; see Rosenbaum, Ziegler, Winocur, Grady, & Moscovitch, 2004). Patients were unimpaired in distance and proximity judgments. In contrast, they all failed in route navigation, and left-lesioned patients also showed marginally impaired performance in landmark sequencing. Patients' subjective experience associated with navigation was impoverished and disembodied compared with that of the controls. These results suggest that PPC is crucial for accessing remote spatial memories within an egocentric reference frame that enables both navigation and reexperiencing. Additionally, PPC was found to be necessary to implement specific aspects of allocentric navigation with high demands on spontaneous retrieval. PsycINFO Database Record (c) 2010 APA, all rights reserved.

Orbital navigation, docking and obstacle avoidance as a form of three dimensional model-based image understanding

NASA Technical Reports Server (NTRS)

Beyer, J.; Jacobus, C.; Mitchell, B.

1987-01-01

Range imagery from a laser scanner can be used to provide sufficient information for docking and obstacle avoidance procedures to be performed automatically. Three dimensional model-based computer vision algorithms in development can perform these tasks even with targets which may not be cooperative (that is, objects without special targets or markers to provide unambiguous location points). Roll, pitch and yaw of the vehicle can be taken into account as image scanning takes place, so that these can be corrected when the image is converted from egocentric to world coordinates. Other attributes of the sensor, such as the registered reflectence and texture channels, provide additional data sources for algorithm robustness. Temporal fusion of sensor immages can take place in the work coordinate domain, allowing for the building of complex maps in three dimensional space.

Intelligent single switch wheelchair navigation.

PubMed

Ka, Hyun W; Simpson, Richard; Chung, Younghyun

2012-11-01

We have developed an intelligent single switch scanning interface and wheelchair navigation assistance system, called intelligent single switch wheelchair navigation (ISSWN), to improve driving safety, comfort and efficiency for individuals who rely on single switch scanning as a control method. ISSWN combines a standard powered wheelchair with a laser rangefinder, a single switch scanning interface and a computer. It provides the user with context sensitive and task specific scanning options that reduce driving effort based on an interpretation of sensor data together with user input. Trials performed by 9 able-bodied participants showed that the system significantly improved driving safety and efficiency in a navigation task by significantly reducing the number of switch presses to 43.5% of traditional single switch wheelchair navigation (p < 0.001). All participants made a significant improvement (39.1%; p < 0.001) in completion time after only two trials.

Navigation for the new millennium: Autonomous navigation for Deep Space 1

NASA Technical Reports Server (NTRS)

Reidel, J. E.; Bhaskaran, S.; Synnott, S. P.; Desai, S. D.; Bollman, W. E.; Dumont, P. J.; Halsell, C. A.; Han, D.; Kennedy, B. M.; Null, G. W.;

Calcium transient prevalence across the dendritic arbour predicts place field properties.

PubMed

Sheffield, Mark E J; Dombeck, Daniel A

2015-01-08

Establishing the hippocampal cellular ensemble that represents an animal's environment involves the emergence and disappearance of place fields in specific CA1 pyramidal neurons, and the acquisition of different spatial firing properties across the active population. While such firing flexibility and diversity have been linked to spatial memory, attention and task performance, the cellular and network origin of these place cell features is unknown. Basic integrate-and-fire models of place firing propose that such features result solely from varying inputs to place cells, but recent studies suggest instead that place cells themselves may play an active role through regenerative dendritic events. However, owing to the difficulty of performing functional recordings from place cell dendrites, no direct evidence of regenerative dendritic events exists, leaving any possible connection to place coding unknown. Using multi-plane two-photon calcium imaging of CA1 place cell somata, axons and dendrites in mice navigating a virtual environment, here we show that regenerative dendritic events do exist in place cells of behaving mice, and, surprisingly, their prevalence throughout the arbour is highly spatiotemporally variable. Furthermore, we show that the prevalence of such events predicts the spatial precision and persistence or disappearance of place fields. This suggests that the dynamics of spiking throughout the dendritic arbour may play a key role in forming the hippocampal representation of space.

Calcium transient prevalence across the dendritic arbor predicts place field properties

PubMed Central

Sheffield, Mark E. J.; Dombeck, Daniel A.

2014-01-01

Establishing the hippocampal cellular ensemble that represents an animal’s environment involves the emergence and disappearance of place fields in specific CA1 pyramidal neurons1–4, and the acquisition of different spatial firing properties across the active population5. While such firing flexibility and diversity have been linked to spatial memory, attention and task performance6,7, the cellular and network origin of these place cell features is unknown. Basic integrate-and-fire models of place firing propose that such features result solely from varying inputs to place cells8,9, but recent studies3,10 instead suggest that place cells themselves may play an active role through regenerative dendritic events. However, due to the difficulty of performing functional recordings from place cell dendrites, no direct evidence of regenerative dendritic events exists, leaving any possible connection to place coding unknown. Using multi-plane two-photon calcium imaging of CA1 place cell somata, axons, and dendrites in mice navigating a virtual environment, we show that regenerative dendritic events do exist in place cells of behaving mice and, surprisingly, their prevalence throughout the arbor is highly spatiotemporally variable. Further, we show that the prevalence of such events predicts the spatial precision and persistence or disappearance of place fields. This suggests that the dynamics of spiking throughout the dendritic arbor may play a key role in forming the hippocampal representation of space. PMID:25363782

Are the deficits in navigational abilities present in the Williams syndrome related to deficits in the backward inhibition?

PubMed Central

Foti, Francesca; Sdoia, Stefano; Menghini, Deny; Mandolesi, Laura; Vicari, Stefano; Ferlazzo, Fabio; Petrosini, Laura

2015-01-01

Williams syndrome (WS) is associated with a distinct profile of relatively proficient skills within the verbal domain compared to the severe impairment of visuo-spatial processing. Abnormalities in executive functions and deficits in planning ability and spatial working memory have been described. However, to date little is known about the influence of executive function deficits on navigational abilities in WS. This study aimed at analyzing in WS individuals a specific executive function, the backward inhibition (BI) that allows individuals to flexibly adapt to continuously changing environments. A group of WS individuals and a mental age- and gender-matched group of typically developing children were subjected to three task-switching experiments requiring visuospatial or verbal material to be processed. Results showed that WS individuals exhibited clear BI deficits during visuospatial task-switching paradigms and normal BI effect during verbal task-switching paradigm. Overall, the present results suggest that the BI involvement in updating environment representations during navigation may influence WS navigational abilities. PMID:25852605

Local Use-Dependent Sleep in Wakefulness Links Performance Errors to Learning

PubMed Central

Quercia, Angelica; Zappasodi, Filippo; Committeri, Giorgia; Ferrara, Michele

2018-01-01

Sleep and wakefulness are no longer to be considered as discrete states. During wakefulness brain regions can enter a sleep-like state (off-periods) in response to a prolonged period of activity (local use-dependent sleep). Similarly, during nonREM sleep the slow-wave activity, the hallmark of sleep plasticity, increases locally in brain regions previously involved in a learning task. Recent studies have demonstrated that behavioral performance may be impaired by off-periods in wake in task-related regions. However, the relation between off-periods in wake, related performance errors and learning is still untested in humans. Here, by employing high density electroencephalographic (hd-EEG) recordings, we investigated local use-dependent sleep in wake, asking participants to repeat continuously two intensive spatial navigation tasks. Critically, one task relied on previous map learning (Wayfinding) while the other did not (Control). Behaviorally awake participants, who were not sleep deprived, showed progressive increments of delta activity only during the learning-based spatial navigation task. As shown by source localization, delta activity was mainly localized in the left parietal and bilateral frontal cortices, all regions known to be engaged in spatial navigation tasks. Moreover, during the Wayfinding task, these increments of delta power were specifically associated with errors, whose probability of occurrence was significantly higher compared to the Control task. Unlike the Wayfinding task, during the Control task neither delta activity nor the number of errors increased progressively. Furthermore, during the Wayfinding task, both the number and the amplitude of individual delta waves, as indexes of neuronal silence in wake (off-periods), were significantly higher during errors than hits. Finally, a path analysis linked the use of the spatial navigation circuits undergone to learning plasticity to off periods in wake. In conclusion, local sleep regulation in wakefulness, associated with performance failures, could be functionally linked to learning-related cortical plasticity. PMID:29666574

Assessment of Spatial Navigation and Docking Performance During Simulated Rover Tasks

NASA Technical Reports Server (NTRS)

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.

In Search of the Optimal Path: How Learners at Task Use an Online Dictionary

ERIC Educational Resources Information Center

Hamel, Marie-Josee

2012-01-01

We have analyzed circa 180 navigation paths followed by six learners while they performed three language encoding tasks at the computer using an online dictionary prototype. Our hypothesis was that learners who follow an "optimal path" while navigating within the dictionary, using its search and look-up functions, would have a high chance of…

Examining the effects of an eco-driving message on driver distraction.

PubMed

Rouzikhah, Hossein; King, Mark; Rakotonirainy, Andry

2013-01-01

This paper examines the effects of an eco-driving message on driver distraction. Two in-vehicle distracter tasks were compared with an eco-driving task and a baseline task in an advanced driving simulator. N=22 subjects were asked to perform an eco-driving, CD changing, and a navigation task while engaged in critical manoeuvres during which they were expected to respond to a peripheral detection task (PDT) with total duration of 3.5h. The study involved two sessions over two consecutive days. The results show that drivers' mental workloads are significantly higher during navigation and CD changing tasks in comparison to the two other scenarios. However, eco-driving mental workload is still marginally significant (p∼.05) across different manoeuvres. Similarly, event detection tasks show that drivers miss significantly more events in the navigation and CD changing scenarios in comparison to both the baseline and eco-driving scenario. Analysis of the practice effect shows that drivers' baseline scenario and navigation scenario exhibit significantly less demand on the second day. Drivers also can detect significantly more events on the second day for all scenarios. The authors conclude that even reading a simple message while driving could potentially lead to missing an important event, especially when executing critical manoeuvres. However, there is some evidence of a practice effect which suggests that future research should focus on performance with habitual rather than novel tasks. It is recommended that sending text as an eco-driving message analogous to the study circumstances should not be delivered to drivers on-line when vehicle is in motion. Copyright © 2012 Elsevier Ltd. All rights reserved.

Eye tracking, strategies, and sex differences in virtual navigation.

PubMed

Andersen, Nicolas E; Dahmani, Louisa; Konishi, Kyoko; Bohbot, Véronique D

2012-01-01

Reports of sex differences in wayfinding have typically used paradigms sensitive to the female advantage (navigation by landmarks) or sensitive to the male advantage (navigation by cardinal directions, Euclidian coordinates, environmental geometry, and absolute distances). The current virtual navigation paradigm allowed both men and women an equal advantage. We studied sex differences by systematically varying the number of landmarks. Eye tracking was used to quantify sex differences in landmark utilisation as participants solved an eight-arm radial maze task within different virtual environments. To solve the task, participants were required to remember the locations of target objects within environments containing 0, 2, 4, 6, or 8 landmarks. We found that, as the number of landmarks available in the environment increases, the proportion of time men and women spend looking at landmarks and the number of landmarks they use to find their way increases. Eye tracking confirmed that women rely more on landmarks to navigate, although landmark fixations were also associated with an increase in task completion time. Sex differences in navigational behaviour occurred only in environments devoid of landmarks and disappeared in environments containing multiple landmarks. Moreover, women showed sustained landmark-oriented gaze, while men's decreased over time. Finally, we found that men and women use spatial and response strategies to the same extent. Together, these results shed new light on the discrepancy in landmark utilisation between men and women and help explain the differences in navigational behaviour previously reported. Copyright © 2011 Elsevier Inc. All rights reserved.

Crew performance and communication: Performing a terrain navigation task

NASA Technical Reports Server (NTRS)

Battiste, Vernol; Delzell, Susanne

1993-01-01

A study was conducted to examine the map and route cues pilots use while navigating under controlled, but realistic, nap-of-the-earth (NOE) flight conditions. US Army helicopter flight crews were presented a map and route overlay and asked to perform normal mission planning. They then viewed a video-recording of the out-the-window scene during low-level flights, without the route overlay, and were asked periodically to locate their current position on the map. The pilots and navigators were asked to communicate normally during the planning and flight phases. During each flight the navigator's response time, accuracy, and subjective workload were assessed. Post-flight NASA-TLX workload ratings were collected. No main effect of map orientation (north-up vs. track-up) was found for errors or response times on any of the tasks evaluated. Navigators in the north-up group rated their workload lower than those in the track-up group.

A comparison of human performance in figural and navigational versions of the traveling salesman problem.

PubMed

Blaser, R E; Wilber, Julie

2013-11-01

Performance on a typical pen-and-paper (figural) version of the Traveling Salesman Problem was compared to performance on a room-sized navigational version of the same task. Nine configurations were designed to examine the use of the nearest-neighbor (NN), cluster approach, and convex-hull strategies. Performance decreased with an increasing number of nodes internal to the hull, and improved when the NN strategy produced the optimal path. There was no overall difference in performance between figural and navigational task modalities. However, there was an interaction between modality and configuration, with evidence that participants relied more heavily on the NN strategy in the figural condition. Our results suggest that participants employed similar, but not identical, strategies when solving figural and navigational versions of the problem. Surprisingly, there was no evidence that participants favored global strategies in the figural version and local strategies in the navigational version.

Clinical governance—watchword or buzzword?

PubMed Central

Campbell, A.

2001-01-01

In the latest reform of the National Health Service great emphasis has been placed on the achievement and maintenance of quality. Mechanisms for ensuring this are being set up under the general title of "clinical governance". What is the meaning of this term? The metaphor behind the phrase is of navigation through stormy seas, but who guides the helmsman? Clinical ethics committees could have a part to play in these changes, provided their role is properly understood. Clinical governance is concerned with management according to an agreed set of aims. The task of ethics committees is Socratic rather than managerial. They should ask fundamental questions about the ethical norms of the services provided and give critical appraisal of the moral character of institutional policies. If these tasks are carried out then governance may become a watchword rather than just another buzzword. Key Words: Governance • quality • National Health Service (NHS) • ethics committees • Socratic method NHS PMID:11314615

Wind shear predictive detector technology study status

NASA Technical Reports Server (NTRS)

Gandolfi, C.

1990-01-01

Among the different elements to be investigated when considering the Wind Shear hazard, the Aeronautical Navigation Technical Service (STNA/3E), whose task is to participate in the development of new technologies and equipments, focused its effort on airborne and ground sensors for the detection of low-level wind shear. The first task, initiated in 1986, consists in the evaluation of three candidate techniques for forward-looking sensors: lidar, sodar, and radar. No development is presently foreseen for an infrared based air turbulence advance warning system although some flight experiments took place in the 70's. A Thomson infrared radiometer was then installed on an Air France Boeing 707 to evaluate its capability of detecting clear air turbulence. The conclusion showed that this technique was apparently able to detect cloud layers but that additional experiments were needed; on the other hand, the rarity of the phenomenon and the difficulty in operating on a commercial aircraft were also mentioned.

Patterns of task and network actions performed by navigators to facilitate cancer care.

PubMed

Clark, Jack A; Parker, Victoria A; Battaglia, Tracy A; Freund, Karen M

2014-01-01

Patient navigation is a widely implemented intervention to facilitate access to care and reduce disparities in cancer care, but the activities of navigators are not well characterized. The aim of this study is to describe what patient navigators actually do and explore patterns of activity that clarify the roles they perform in facilitating cancer care. We conducted field observations of nine patient navigation programs operating in diverse health settings of the national patient navigation research program, including 34 patient navigators, each observed an average of four times. Trained observers used a structured observation protocol to code as they recorded navigator actions and write qualitative field notes capturing all activities in 15-minute intervals during observations ranging from 2 to 7 hours; yielding a total of 133 observations. Rates of coded activity were analyzed using numerical cluster analysis of identified patterns, informed by qualitative analysis of field notes. Six distinct patterns of navigator activity were identified, which differed most relative to how much time navigators spent directly interacting with patients and how much time they spent dealing with medical records and documentation tasks. Navigator actions reveal a complex set of roles in which navigators both provide the direct help to patients denoted by their title and also carry out a variety of actions that function to keep the health system operating smoothly. Working to navigate patients through complex health services entails working to repair the persistent challenges of health services that can render them inhospitable to patients. The organizations that deploy navigators might learn from navigators' efforts and explore alternative approaches, structures, or systems of care in addressing both the barriers patients face and the complex solutions navigators create in helping patients.

Information access in a dual-task context: testing a model of optimal strategy selection.

PubMed

Wickens, C D; Seidler, K S

1997-09-01

Pilots were required to access information from a hierarchical aviation database by navigating under single-task conditions (Experiment 1) and when this task was time-shared with an altitude-monitoring task of varying bandwidth and priority (Experiment 2). In dual-task conditions, pilots had 2 viewports available, 1 always used for the information task and the other to be allocated to either task. Dual-task strategy, inferred from the decision of which task to allocate to the 2nd viewport, revealed that allocation was generally biased in favor of the monitoring task and was only partly sensitive to the difficulty of the 2 tasks and their relative priorities. Some dominant sources of navigational difficulties failed to adaptively influence selection strategy. The implications of the results are to provide tools for jumping to the top of the database, to provide 2 viewports into the common database, and to provide training as to the optimum viewport management strategy in a multitask environment.

Information access in a dual-task context: testing a model of optimal strategy selection

NASA Technical Reports Server (NTRS)

Wickens, C. D.; Seidler, K. S.

1997-01-01

Pilots were required to access information from a hierarchical aviation database by navigating under single-task conditions (Experiment 1) and when this task was time-shared with an altitude-monitoring task of varying bandwidth and priority (Experiment 2). In dual-task conditions, pilots had 2 viewports available, 1 always used for the information task and the other to be allocated to either task. Dual-task strategy, inferred from the decision of which task to allocate to the 2nd viewport, revealed that allocation was generally biased in favor of the monitoring task and was only partly sensitive to the difficulty of the 2 tasks and their relative priorities. Some dominant sources of navigational difficulties failed to adaptively influence selection strategy. The implications of the results are to provide tools for jumping to the top of the database, to provide 2 viewports into the common database, and to provide training as to the optimum viewport management strategy in a multitask environment.

Inattentional blindness increased with augmented reality surgical navigation.

PubMed

Dixon, Benjamin J; Daly, Michael J; Chan, Harley H L; Vescan, Allan; Witterick, Ian J; Irish, Jonathan C

2014-01-01

Augmented reality (AR) surgical navigation systems, designed to increase accuracy and efficiency, have been shown to negatively impact on attention. We wished to assess the effect "head-up" AR displays have on attention, efficiency, and accuracy, while performing a surgical task, compared with the same information being presented on a submonitor (SM). Fifty experienced otolaryngology surgeons (n = 42) and senior otolaryngology trainees (n = 8) performed an endoscopic surgical navigation exercise on a predissected cadaveric model. Computed tomography-generated anatomic contours were fused with the endoscopic image to provide an AR view. Subjects were randomized to perform the task with a standard endoscopic monitor with the AR navigation displayed on an SM or with AR as a single display. Accuracy, task completion time, and the recognition of unexpected findings (a foreign body and a critical complication) were recorded. Recognition of the foreign body was significantly better in the SM group (15/25 [60%]) compared with the AR alone group (8/25 [32%]; p = 0.02). There was no significant difference in task completion time (p = 0.83) or accuracy (p = 0.78) between the two groups. Providing identical surgical navigation on a SM, rather than on a single head-up display, reduced the level of inattentional blindness as measured by detection of unexpected findings. These gains were achieved without any measurable impact on efficiency or accuracy. AR displays may distract the user and we caution injudicious adoption of this technology for medical procedures.

Deep imitation learning for 3D navigation tasks.

PubMed

Hussein, Ahmed; Elyan, Eyad; Gaber, Mohamed Medhat; Jayne, Chrisina

2018-01-01

Deep learning techniques have shown success in learning from raw high-dimensional data in various applications. While deep reinforcement learning is recently gaining popularity as a method to train intelligent agents, utilizing deep learning in imitation learning has been scarcely explored. Imitation learning can be an efficient method to teach intelligent agents by providing a set of demonstrations to learn from. However, generalizing to situations that are not represented in the demonstrations can be challenging, especially in 3D environments. In this paper, we propose a deep imitation learning method to learn navigation tasks from demonstrations in a 3D environment. The supervised policy is refined using active learning in order to generalize to unseen situations. This approach is compared to two popular deep reinforcement learning techniques: deep-Q-networks and Asynchronous actor-critic (A3C). The proposed method as well as the reinforcement learning methods employ deep convolutional neural networks and learn directly from raw visual input. Methods for combining learning from demonstrations and experience are also investigated. This combination aims to join the generalization ability of learning by experience with the efficiency of learning by imitation. The proposed methods are evaluated on 4 navigation tasks in a 3D simulated environment. Navigation tasks are a typical problem that is relevant to many real applications. They pose the challenge of requiring demonstrations of long trajectories to reach the target and only providing delayed rewards (usually terminal) to the agent. The experiments show that the proposed method can successfully learn navigation tasks from raw visual input while learning from experience methods fail to learn an effective policy. Moreover, it is shown that active learning can significantly improve the performance of the initially learned policy using a small number of active samples.

Remote controlled robot assisted cardiac navigation: feasibility assessment and validation in a porcine model.

PubMed

Ganji, Yusof; Janabi-Sharifi, Farrokh; Cheema, Asim N

2011-12-01

Despite the recent advances in catheter design and technology, intra-cardiac navigation during electrophysiology procedures remains challenging. Incorporation of imaging along with magnetic or robotic guidance may improve navigation accuracy and procedural safety. In the present study, the in vivo performance of a novel remote controlled Robot Assisted Cardiac Navigation System (RACN) was evaluated in a porcine model. The navigation catheter and target sensor were advanced to the right atrium using fluoroscopic and intra-cardiac echo guidance. The target sensor was positioned at three target locations in the right atrium (RA) and the navigation task was completed by an experienced physician using both manual and RACN guidance. The navigation time, final distance between the catheter tip and target sensor, and variability in final catheter tip position were determined and compared for manual and RACN guided navigation. The experiments were completed in three animals and five measurements recorded for each target location. The mean distance (mm) between catheter tip and target sensor at the end of the navigation task was significantly less using RACN guidance compared with manual navigation (5.02 ± 0.31 vs. 9.66 ± 2.88, p = 0.050 for high RA, 9.19 ± 1.13 vs. 13.0 ± 1.00, p = 0.011 for low RA and 6.77 ± 0.59 vs. 15.66 ± 2.51, p = 0.003 for tricuspid valve annulus). The average time (s) needed to complete the navigation task was significantly longer by RACN guided navigation compared with manual navigation (43.31 ± 18.19 vs. 13.54 ± 1.36, p = 0.047 for high RA, 43.71 ± 11.93 vs. 22.71 ± 3.79, p = 0.043 for low RA and 37.84 ± 3.71 vs. 16.13 ± 4.92, p = 0.003 for tricuspid valve annulus. RACN guided navigation resulted in greater consistency in performance compared with manual navigation as evidenced by lower variability in final distance measurements (0.41 vs. 0.99 mm, p = 0.04). This study demonstrated the safety and feasibility of the RACN system for cardiac navigation. The results demonstrated that RACN performed comparably with manual navigation, with improved precision and consistency for targets located in and near the right atrial chamber. Copyright © 2011 John Wiley & Sons, Ltd.

Using Grid Benchmarks for Dynamic Scheduling of Grid Applications

NASA Technical Reports Server (NTRS)

Frumkin, Michael; Hood, Robert

2003-01-01

Navigation or dynamic scheduling of applications on computational grids can be improved through the use of an application-specific characterization of grid resources. Current grid information systems provide a description of the resources, but do not contain any application-specific information. We define a GridScape as dynamic state of the grid resources. We measure the dynamic performance of these resources using the grid benchmarks. Then we use the GridScape for automatic assignment of the tasks of a grid application to grid resources. The scalability of the system is achieved by limiting the navigation overhead to a few percent of the application resource requirements. Our task submission and assignment protocol guarantees that the navigation system does not cause grid congestion. On a synthetic data mining application we demonstrate that Gridscape-based task assignment reduces the application tunaround time.

The Deep Space Network. An instrument for radio navigation of deep space probes

NASA Technical Reports Server (NTRS)

Renzetti, N. A.; Jordan, J. F.; Berman, A. L.; Wackley, J. A.; Yunck, T. P.

1982-01-01

The Deep Space Network (DSN) network configurations used to generate the navigation observables and the basic process of deep space spacecraft navigation, from data generation through flight path determination and correction are described. Special emphasis is placed on the DSN Systems which generate the navigation data: the DSN Tracking and VLBI Systems. In addition, auxiliary navigational support functions are described.

From self-assessment to frustration, a small step toward autonomy in robotic navigation

PubMed Central

Jauffret, Adrien; Cuperlier, Nicolas; Tarroux, Philippe; Gaussier, Philippe

2013-01-01

Autonomy and self-improvement capabilities are still challenging in the fields of robotics and machine learning. Allowing a robot to autonomously navigate in wide and unknown environments not only requires a repertoire of robust strategies to cope with miscellaneous situations, but also needs mechanisms of self-assessment for guiding learning and for monitoring strategies. Monitoring strategies requires feedbacks on the behavior's quality, from a given fitness system in order to take correct decisions. In this work, we focus on how a second-order controller can be used to (1) manage behaviors according to the situation and (2) seek for human interactions to improve skills. Following an incremental and constructivist approach, we present a generic neural architecture, based on an on-line novelty detection algorithm that may be able to self-evaluate any sensory-motor strategies. This architecture learns contingencies between sensations and actions, giving the expected sensation from the previous perception. Prediction error, coming from surprising events, provides a measure of the quality of the underlying sensory-motor contingencies. We show how a simple second-order controller (emotional system) based on the prediction progress allows the system to regulate its behavior to solve complex navigation tasks and also succeeds in asking for help if it detects dead-lock situations. We propose that this model could be a key structure toward self-assessment and autonomy. We made several experiments that can account for such properties for two different strategies (road following and place cells based navigation) in different situations. PMID:24115931

Dual Motor-Cognitive Virtual Reality Training Impacts Dual-Task Performance in Freezing of Gait.

PubMed

Killane, Isabelle; Fearon, Conor; Newman, Louise; McDonnell, Conor; Waechter, Saskia M; Sons, Kristian; Lynch, Timothy; Reilly, Richard B

2015-11-01

Freezing of gait (FOG), an episodic gait disturbance characterized by the inability to generate effective stepping, occurs in more than half of Parkinson's disease patients. It is associated with both executive dysfunction and attention and becomes most evident during dual tasking (performing two tasks simultaneously). This study examined the effect of dual motor-cognitive virtual reality training on dual-task performance in FOG. Twenty community dwelling participants with Parkinson's disease (13 with FOG, 7 without FOG) participated in a pre-assessment, eight 20-minute intervention sessions, and a post-assessment. The intervention consisted of a virtual reality maze (DFKI, Germany) through which participants navigated by stepping-in-place on a balance board (Nintendo, Japan) under time pressure. This was combined with a cognitive task (Stroop test), which repeatedly divided participants' attention. The primary outcome measures were pre- and post-intervention differences in motor (stepping time, symmetry, rhythmicity) and cognitive (accuracy, reaction time) performance during single- and dual-tasks. Both assessments consisted of 1) a single cognitive task 2) a single motor task, and 3) a dual motor-cognitive task. Following the intervention, there was significant improvement in dual-task cognitive and motor parameters (stepping time and rhythmicity), dual-task effect for those with FOG and a noteworthy improvement in FOG episodes. These improvements were less significant for those without FOG. This is the first study to show benefit of a dual motor-cognitive approach on dual-task performance in FOG. Advances in such virtual reality interventions for home use could substantially improve the quality of life for patients who experience FOG.

Spatial learning while navigating with severely degraded viewing: The role of attention and mobility monitoring

PubMed Central

Rand, Kristina M.; Creem-Regehr, Sarah H.; Thompson, William B.

2015-01-01

The ability to navigate without getting lost is an important aspect of quality of life. In five studies, we evaluated how spatial learning is affected by the increased demands of keeping oneself safe while walking with degraded vision (mobility monitoring). We proposed that safe low-vision mobility requires attentional resources, providing competition for those needed to learn a new environment. In Experiments 1 and 2 participants navigated along paths in a real-world indoor environment with simulated degraded vision or normal vision. Memory for object locations seen along the paths was better with normal compared to degraded vision. With degraded vision, memory was better when participants were guided by an experimenter (low monitoring demands) versus unguided (high monitoring demands). In Experiments 3 and 4, participants walked while performing an auditory task. Auditory task performance was superior with normal compared to degraded vision. With degraded vision, auditory task performance was better when guided compared to unguided. In Experiment 5, participants performed both the spatial learning and auditory tasks under degraded vision. Results showed that attention mediates the relationship between mobility-monitoring demands and spatial learning. These studies suggest that more attention is required and spatial learning is impaired when navigating with degraded viewing. PMID:25706766

Accuracy of a real-time surgical navigation system for the placement of quad zygomatic implants in the severe atrophic maxilla: A pilot clinical study.

PubMed

Hung, Kuo-Feng; Wang, Feng; Wang, Hao-Wei; Zhou, Wen-Jie; Huang, Wei; Wu, Yi-Qun

2017-06-01

A real-time surgical navigation system potentially increases the accuracy when used for quad-zygomatic implant placement. To evaluate the accuracy of a real-time surgical navigation system when used for quad zygomatic implant placement. Patients with severely atrophic maxillae were prospectively recruited. Four trajectories for implants were planned, and zygomatic implants were placed using a real-time surgical navigation system. The planned-placed distance deviations at entry (entry deviation）points, exit (exit deviation) points, and angle deviation of axes (angle deviation) were measured on fused operation images. The differences of all the deviations between different groups, classified based on the lengths and locations of implants, were analysed. A P value of < 0.05 indicated statistical significance. Forty zygomatic implants were placed as planned in 10 patients. The entry deviation, exit deviation and angle deviation were 1.35 ± 0.75 mm, 2.15 mm ± 0.95 mm, and 2.05 ± 1.02 degrees, respectively. The differences of all deviations were not significant, irrespective of the lengths (P = .259, .158, and .914, respectively) or locations of the placed implants (P = .698, .072, and .602, respectively). A real-time surgical navigation system used for the placement of quad zygomatic implants demonstrated a high level of accuracy with only minimal planned-placed deviations, irrespective of the lengths or locations of the implants. © 2017 Wiley Periodicals, Inc.

Sensor image prediction techniques

NASA Astrophysics Data System (ADS)

Stenger, A. J.; Stone, W. R.; Berry, L.; Murray, T. J.

1981-02-01

The preparation of prediction imagery is a complex, costly, and time consuming process. Image prediction systems which produce a detailed replica of the image area require the extensive Defense Mapping Agency data base. The purpose of this study was to analyze the use of image predictions in order to determine whether a reduced set of more compact image features contains enough information to produce acceptable navigator performance. A job analysis of the navigator's mission tasks was performed. It showed that the cognitive and perceptual tasks he performs during navigation are identical to those performed for the targeting mission function. In addition, the results of the analysis of his performance when using a particular sensor can be extended to the analysis of this mission tasks using any sensor. An experimental approach was used to determine the relationship between navigator performance and the type of amount of information in the prediction image. A number of subjects were given image predictions containing varying levels of scene detail and different image features, and then asked to identify the predicted targets in corresponding dynamic flight sequences over scenes of cultural, terrain, and mixed (both cultural and terrain) content.

Maintaining a Cognitive Map in Darkness: The Need to Fuse Boundary Knowledge with Path Integration

PubMed Central

Cheung, Allen; Ball, David; Milford, Michael; Wyeth, Gordon; Wiles, Janet

2012-01-01

Spatial navigation requires the processing of complex, disparate and often ambiguous sensory data. The neurocomputations underpinning this vital ability remain poorly understood. Controversy remains as to whether multimodal sensory information must be combined into a unified representation, consistent with Tolman's “cognitive map”, or whether differential activation of independent navigation modules suffice to explain observed navigation behaviour. Here we demonstrate that key neural correlates of spatial navigation in darkness cannot be explained if the path integration system acted independently of boundary (landmark) information. In vivo recordings demonstrate that the rodent head direction (HD) system becomes unstable within three minutes without vision. In contrast, rodents maintain stable place fields and grid fields for over half an hour without vision. Using a simple HD error model, we show analytically that idiothetic path integration (iPI) alone cannot be used to maintain any stable place representation beyond two to three minutes. We then use a measure of place stability based on information theoretic principles to prove that featureless boundaries alone cannot be used to improve localization above chance level. Having shown that neither iPI nor boundaries alone are sufficient, we then address the question of whether their combination is sufficient and – we conjecture – necessary to maintain place stability for prolonged periods without vision. We addressed this question in simulations and robot experiments using a navigation model comprising of a particle filter and boundary map. The model replicates published experimental results on place field and grid field stability without vision, and makes testable predictions including place field splitting and grid field rescaling if the true arena geometry differs from the acquired boundary map. We discuss our findings in light of current theories of animal navigation and neuronal computation, and elaborate on their implications and significance for the design, analysis and interpretation of experiments. PMID:22916006

Place and response learning in human virtual navigation: behavioral measures and gender differences.

PubMed

Schmitzer-Torbert, Neil

2007-04-01

Two experiments examined the use of place and response strategies by humans navigating virtual multiple T mazes. In Experiment 1, probe trials revealed that participants commonly used place and response strategies, and place strategies were more frequent early in training, whereas response strategies were more frequent late in training. Compared with women, men learned the correct path through the maze more quickly and developed a more stable route through the maze. In Experiment 2, participants were trained to locate 2 targets. One target required participants to use either a place or response strategy, whereas the other target could be found using either strategy. Accuracy improved faster for place training compared with response training, and women outperformed men in both groups. Probe trials testing transfer of the imposed strategy to the other target found faster transfer for place training than for response training and that women demonstrated faster transfer than men. Accuracy on probe trials was correlated with poor route stability in the place-trained group and with good route stability in the response-trained group, indicating that navigation strategy use may be related to measures of improvement in performance on normal trials. (c) 2007 APA, all rights reserved

Pilot perception and confidence of location during a simulated helicopter navigation task.

PubMed

Yang, Ji Hyun; Cowden, Bradley T; Kennedy, Quinn; Schramm, Harrison; Sullivan, Joseph

2013-09-01

This paper aims to provide insights into human perception, navigation performance, and confidence in helicopter overland navigation. Helicopter overland navigation is a challenging mission area because it is a complex cognitive task, and failing to recognize when the aircraft is off-course can lead to operational failures and mishaps. A human-in-the-loop experiment to investigate pilot perception during simulated overland navigation by analyzing actual navigation trajectory, pilots' perceived location, and corresponding confidence levels was designed. There were 15 military officers with prior overland navigation experience who completed 4 simulated low-level navigation routes, 2 of which entailed auto-navigation. This route was paused roughly every 30 s for the subject to mark their perceived location on the map and their confidence level using a customized program. Analysis shows that there is no correlation between perceived and actual location of the aircraft, nor between confidence level and actual location. There is, however, some evidence that there is a correlation (rho = -0.60 to approximately 0.65) between perceived location and intended route of flight, suggesting that there is a bias toward believing one is on the intended flight route. If aviation personnel can proactively identify the circumstances in which usual misperceptions occur in navigation, they may reduce mission failure and accident rate. Fleet squadrons and instructional commands can benefit from this study to improve operations that require low-level flight while also improving crew resource management.

The effects of mental representation on performance in a navigation task

NASA Technical Reports Server (NTRS)

Barshi, Immanuel; Healy, Alice F.

2002-01-01

In three experiments, we investigated the mental representations employed when instructions were followed that involved navigation in a space displayed as a grid on a computer screen. Performance was affected much more by the number of instructional units than by the number of words per unit. Performance in a three-dimensional space was independent of the number of dimensions along which participants navigated. However, memory for and accuracy in following the instructions were reduced when the task required mentally representing a three-dimensional space, as compared with representing a two-dimensional space, although the words used in the instructions were identical in the two cases. These results demonstrate the interdependence of verbal and spatial memory representations, because individuals' immediate memory for verbal navigation instructions is affected by their mental representation of the space referred to by the instructions.

Hand-gesture-based sterile interface for the operating room using contextual cues for the navigation of radiological images

PubMed Central

Jacob, Mithun George; Wachs, Juan Pablo; Packer, Rebecca A

2013-01-01

This paper presents a method to improve the navigation and manipulation of radiological images through a sterile hand gesture recognition interface based on attentional contextual cues. Computer vision algorithms were developed to extract intention and attention cues from the surgeon's behavior and combine them with sensory data from a commodity depth camera. The developed interface was tested in a usability experiment to assess the effectiveness of the new interface. An image navigation and manipulation task was performed, and the gesture recognition accuracy, false positives and task completion times were computed to evaluate system performance. Experimental results show that gesture interaction and surgeon behavior analysis can be used to accurately navigate, manipulate and access MRI images, and therefore this modality could replace the use of keyboard and mice-based interfaces. PMID:23250787

Hand-gesture-based sterile interface for the operating room using contextual cues for the navigation of radiological images.

PubMed

Jacob, Mithun George; Wachs, Juan Pablo; Packer, Rebecca A

2013-06-01

This paper presents a method to improve the navigation and manipulation of radiological images through a sterile hand gesture recognition interface based on attentional contextual cues. Computer vision algorithms were developed to extract intention and attention cues from the surgeon's behavior and combine them with sensory data from a commodity depth camera. The developed interface was tested in a usability experiment to assess the effectiveness of the new interface. An image navigation and manipulation task was performed, and the gesture recognition accuracy, false positives and task completion times were computed to evaluate system performance. Experimental results show that gesture interaction and surgeon behavior analysis can be used to accurately navigate, manipulate and access MRI images, and therefore this modality could replace the use of keyboard and mice-based interfaces.

A Usability Study of a Serious Game in Cognitive Rehabilitation: A Compensatory Navigation Training in Acquired Brain Injury Patients

PubMed Central

van der Kuil, Milan N. A.; Visser-Meily, Johanna M. A.; Evers, Andrea W. M.; van der Ham, Ineke J. M.

2018-01-01

Acquired brain injury patients often report navigation impairments. A cognitive rehabilitation therapy has been designed in the form of a serious game. The aim of the serious game is to aid patients in the development of compensatory navigation strategies by providing exercises in 3D virtual environments on their home computers. The objective of this study was to assess the usability of three critical gaming attributes: movement control in 3D virtual environments, instruction modality and feedback timing. Thirty acquired brain injury patients performed three tasks in which objective measures of usability were obtained. Mouse controlled movement was compared to keyboard controlled movement in a navigation task. Text-based instructions were compared to video-based instructions in a knowledge acquisition task. The effect of feedback timing on performance and motivation was examined in a navigation training game. Subjective usability ratings of all design options were assessed using questionnaires. Results showed that mouse controlled interaction in 3D environments is more effective than keyboard controlled interaction. Patients clearly preferred video-based instructions over text-based instructions, even though video-based instructions were not more effective in context of knowledge acquisition and comprehension. No effect of feedback timing was found on performance and motivation in games designed to train navigation abilities. Overall appreciation of the serious game was positive. The results provide valuable insights in the design choices that facilitate the transfer of skills from serious games to real-life situations. PMID:29922196

A Usability Study of a Serious Game in Cognitive Rehabilitation: A Compensatory Navigation Training in Acquired Brain Injury Patients.

PubMed

van der Kuil, Milan N A; Visser-Meily, Johanna M A; Evers, Andrea W M; van der Ham, Ineke J M

2018-01-01

Acquired brain injury patients often report navigation impairments. A cognitive rehabilitation therapy has been designed in the form of a serious game. The aim of the serious game is to aid patients in the development of compensatory navigation strategies by providing exercises in 3D virtual environments on their home computers. The objective of this study was to assess the usability of three critical gaming attributes: movement control in 3D virtual environments, instruction modality and feedback timing. Thirty acquired brain injury patients performed three tasks in which objective measures of usability were obtained. Mouse controlled movement was compared to keyboard controlled movement in a navigation task. Text-based instructions were compared to video-based instructions in a knowledge acquisition task. The effect of feedback timing on performance and motivation was examined in a navigation training game. Subjective usability ratings of all design options were assessed using questionnaires. Results showed that mouse controlled interaction in 3D environments is more effective than keyboard controlled interaction. Patients clearly preferred video-based instructions over text-based instructions, even though video-based instructions were not more effective in context of knowledge acquisition and comprehension. No effect of feedback timing was found on performance and motivation in games designed to train navigation abilities. Overall appreciation of the serious game was positive. The results provide valuable insights in the design choices that facilitate the transfer of skills from serious games to real-life situations.

Object Persistence Enhances Spatial Navigation: A Case Study in Smartphone Vision Science.

PubMed

Liverence, Brandon M; Scholl, Brian J

2015-07-01

Violations of spatiotemporal continuity disrupt performance in many tasks involving attention and working memory, but experiments on this topic have been limited to the study of moment-by-moment on-line perception, typically assessed by passive monitoring tasks. We tested whether persisting object representations also serve as underlying units of longer-term memory and active spatial navigation, using a novel paradigm inspired by the visual interfaces common to many smartphones. Participants used key presses to navigate through simple visual environments consisting of grids of icons (depicting real-world objects), only one of which was visible at a time through a static virtual window. Participants found target icons faster when navigation involved persistence cues (via sliding animations) than when persistence was disrupted (e.g., via temporally matched fading animations), with all transitions inspired by smartphone interfaces. Moreover, this difference occurred even after explicit memorization of the relevant information, which demonstrates that object persistence enhances spatial navigation in an automatic and irresistible fashion. © The Author(s) 2015.

33 CFR 156.118 - Advance notice of transfer.

Code of Federal Regulations, 2014 CFR

2014-07-01

... COTP of the time and place of each transfer operation at least 4 hours before it begins for facilities... the time and place of each transfer operation, as specified by the COTP, at least 4 hours before it... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Advance notice of transfer. 156...

33 CFR 156.118 - Advance notice of transfer.

Code of Federal Regulations, 2011 CFR

2011-07-01

... COTP of the time and place of each transfer operation at least 4 hours before it begins for facilities... the time and place of each transfer operation, as specified by the COTP, at least 4 hours before it... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Advance notice of transfer. 156...

33 CFR 156.118 - Advance notice of transfer.

Code of Federal Regulations, 2013 CFR

2013-07-01

... COTP of the time and place of each transfer operation at least 4 hours before it begins for facilities... the time and place of each transfer operation, as specified by the COTP, at least 4 hours before it... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Advance notice of transfer. 156...

33 CFR 156.118 - Advance notice of transfer.

Code of Federal Regulations, 2010 CFR

2010-07-01

... COTP of the time and place of each transfer operation at least 4 hours before it begins for facilities... the time and place of each transfer operation, as specified by the COTP, at least 4 hours before it... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Advance notice of transfer. 156...

33 CFR 156.118 - Advance notice of transfer.

Code of Federal Regulations, 2012 CFR

2012-07-01

... COTP of the time and place of each transfer operation at least 4 hours before it begins for facilities... the time and place of each transfer operation, as specified by the COTP, at least 4 hours before it... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Advance notice of transfer. 156...

Navigation performance in virtual environments varies with fractal dimension of landscape.

PubMed

Juliani, Arthur W; Bies, Alexander J; Boydston, Cooper R; Taylor, Richard P; Sereno, Margaret E

2016-09-01

Fractal geometry has been used to describe natural and built environments, but has yet to be studied in navigational research. In order to establish a relationship between the fractal dimension (D) of a natural environment and humans' ability to navigate such spaces, we conducted two experiments using virtual environments that simulate the fractal properties of nature. In Experiment 1, participants completed a goal-driven search task either with or without a map in landscapes that varied in D. In Experiment 2, participants completed a map-reading and location-judgment task in separate sets of fractal landscapes. In both experiments, task performance was highest at the low-to-mid range of D, which was previously reported as most preferred and discriminable in studies of fractal aesthetics and discrimination, respectively, supporting a theory of visual fluency. The applicability of these findings to architecture, urban planning, and the general design of constructed spaces is discussed.

Hippocampal place cell encoding of sloping terrain.

PubMed

Porter, Blake S; Schmidt, Robert; Bilkey, David K

2018-05-21

Effective navigation relies on knowledge of one's environment. A challenge to effective navigation is accounting for the time and energy costs of routes. Irregular terrain in ecological environments poses a difficult navigational problem as organisms ought to avoid effortful slopes to minimize travel costs. Route planning and navigation have previously been shown to involve hippocampal place cells and their ability to encode and store information about an organism's environment. However, little is known about how place cells may encode the slope of space and associated energy costs as experiments are traditionally carried out in flat, horizontal environments. We set out to investigate how dorsal-CA1 place cells in rats encode systematic changes to the slope of an environment by tilting a shuttle box from flat to 15° and 25° while minimizing external cue change. Overall, place cell encoding of tilted space was as robust as their encoding of flat ground as measured by traditional place cell metrics such as firing rates, spatial information, coherence, and field size. A large majority of place cells did, however, respond to slope by undergoing partial, complex remapping when the environment was shifted from one tilt angle to another. The propensity for place cells to remap did not, however, depend on the vertical distance the field shifted. Changes in slope also altered the temporal coding of information as measured by the rate of theta phase precession of place cell spikes, which decreased with increasing tilt angles. Together these observations indicate that place cells are sensitive to relatively small changes in terrain slope and that terrain slope may be an important source of information for organizing place cell ensembles. The terrain slope information encoded by place cells could be utilized by efferent regions to determine energetically advantageous routes to goal locations. This article is protected by copyright. All rights reserved. © 2018 Wiley Periodicals, Inc.

"I have often walked down this street before": fMRI studies on the hippocampus and other structures during mental navigation of an old environment.

PubMed

Rosenbaum, R Shayna; Ziegler, Marilyne; Winocur, Gordon; Grady, Cheryl L; Moscovitch, Morris

2004-01-01

The role of the hippocampus in recent spatial memory has been well documented in patients with damage to this structure, but there is now evidence that the hippocampus may not be needed for the storage and recovery of a spatial layout that was experienced long before injury. Such preservation may rely, instead, on a network of dissociable, extra-hippocampal regions implicated in topographical orientation. Using functional magnetic resonance imaging (fMRI), we investigated this hypothesis in healthy individuals with extensive experience navigating in a large-scale urban environment (downtown Toronto). Participants were scanned as they performed mental navigation tasks that emphasized different types of spatial representations. Tasks included proximity judgments, distance judgments, landmark sequencing, and blocked-route problem-solving. The following regions were engaged to varying degrees depending on the processing demands of each task: retrosplenial cortex, believed to be involved in assigning directional significance to locales within a relatively allocentric framework; medial and posterior parietal cortex, concerned with processing space within egocentric coordinates during imagined movement; and regions of prefrontal cortex, present in tasks heavily dependent on working memory. In a second, event-related experiment, a distinct area of inferotemporal cortex was revealed during identification of familiar landmarks relative to unknown buildings in addition to activation of many of those regions identified in the navigation tasks. This result suggests that familiar landmarks are strongly integrated with the spatial context in which they were experienced. Importantly, right medial temporal lobe activity was observed, its magnitude equivalent across all tasks, though the core of the activated region was in the parahippocampal gyrus, barely touching the hippocampus proper. Copyright 2004 Wiley-Liss, Inc.

Computer-assisted navigation in orthopedic surgery.

PubMed

Mavrogenis, Andreas F; Savvidou, Olga D; Mimidis, George; Papanastasiou, John; Koulalis, Dimitrios; Demertzis, Nikolaos; Papagelopoulos, Panayiotis J

2013-08-01

Computer-assisted navigation has a role in some orthopedic procedures. It allows the surgeons to obtain real-time feedback and offers the potential to decrease intra-operative errors and optimize the surgical result. Computer-assisted navigation systems can be active or passive. Active navigation systems can either perform surgical tasks or prohibit the surgeon from moving past a predefined zone. Passive navigation systems provide intraoperative information, which is displayed on a monitor, but the surgeon is free to make any decisions he or she deems necessary. This article reviews the available types of computer-assisted navigation, summarizes the clinical applications and reviews the results of related series using navigation, and informs surgeons of the disadvantages and pitfalls of computer-assisted navigation in orthopedic surgery. Copyright 2013, SLACK Incorporated.

Navigation/Prop Software Suite

NASA Technical Reports Server (NTRS)

Bruchmiller, Tomas; Tran, Sanh; Lee, Mathew; Bucker, Scott; Bupane, Catherine; Bennett, Charles; Cantu, Sergio; Kwong, Ping; Propst, Carolyn

2012-01-01

Navigation (Nav)/Prop software is used to support shuttle mission analysis, production, and some operations tasks. The Nav/Prop suite containing configuration items (CIs) resides on IPS/Linux workstations. It features lifecycle documents, and data files used for shuttle navigation and propellant analysis for all flight segments. This suite also includes trajectory server, archive server, and RAT software residing on MCC/Linux workstations. Navigation/Prop represents tool versions established during or after IPS Equipment Rehost-3 or after the MCC Rehost.

Lateralized hippocampal oscillations underlie distinct aspects of human spatial memory and navigation.

PubMed

Miller, Jonathan; Watrous, Andrew J; Tsitsiklis, Melina; Lee, Sang Ah; Sheth, Sameer A; Schevon, Catherine A; Smith, Elliot H; Sperling, Michael R; Sharan, Ashwini; Asadi-Pooya, Ali Akbar; Worrell, Gregory A; Meisenhelter, Stephen; Inman, Cory S; Davis, Kathryn A; Lega, Bradley; Wanda, Paul A; Das, Sandhitsu R; Stein, Joel M; Gorniak, Richard; Jacobs, Joshua

2018-06-21

The hippocampus plays a vital role in various aspects of cognition including both memory and spatial navigation. To understand electrophysiologically how the hippocampus supports these processes, we recorded intracranial electroencephalographic activity from 46 neurosurgical patients as they performed a spatial memory task. We measure signals from multiple brain regions, including both left and right hippocampi, and we use spectral analysis to identify oscillatory patterns related to memory encoding and navigation. We show that in the left but not right hippocampus, the amplitude of oscillations in the 1-3-Hz "low theta" band increases when viewing subsequently remembered object-location pairs. In contrast, in the right but not left hippocampus, low-theta activity increases during periods of navigation. The frequencies of these hippocampal signals are slower than task-related signals in the neocortex. These results suggest that the human brain includes multiple lateralized oscillatory networks that support different aspects of cognition.

Common Neural Representations for Visually Guided Reorientation and Spatial Imagery

PubMed Central

Vass, Lindsay K.; Epstein, Russell A.

2017-01-01

Abstract Spatial knowledge about an environment can be cued from memory by perception of a visual scene during active navigation or by imagination of the relationships between nonvisible landmarks, such as when providing directions. It is not known whether these different ways of accessing spatial knowledge elicit the same representations in the brain. To address this issue, we scanned participants with fMRI, while they performed a judgment of relative direction (JRD) task that required them to retrieve real-world spatial relationships in response to either pictorial or verbal cues. Multivoxel pattern analyses revealed several brain regions that exhibited representations that were independent of the cues to access spatial memory. Specifically, entorhinal cortex in the medial temporal lobe and the retrosplenial complex (RSC) in the medial parietal lobe coded for the heading assumed on a particular trial, whereas the parahippocampal place area (PPA) contained information about the starting location of the JRD. These results demonstrate the existence of spatial representations in RSC, ERC, and PPA that are common to visually guided navigation and spatial imagery. PMID:26759482

Virtual reality body motion induced navigational controllers and their effects on simulator sickness and pathfinding.

PubMed

Aldaba, Cassandra N; White, Paul J; Byagowi, Ahmad; Moussavi, Zahra

2017-07-01

Virtual reality (VR) navigation is usually constrained by plausible simulator sickness (SS) and intuitive user interaction. The paper reports on the use of four different degrees of body motion induced navigational VR controllers, a TiltChair, omni-directional treadmill, a manual wheelchair joystick (VRNChair), and a joystick in relation to a participant's SS occurrence and a controller's intuitive utilization. Twenty young adult participants utilized all controllers to navigate through the same VR task environment in separate sessions. Throughout the sessions, SS occurrence was measured from a severity score by a standard SS questionnaire and from body sway by a center of pressure path length with eyes opened and closed. SS occurrence did not significantly differ among the controllers. However, time spent in VR significantly contributed to SS occurrence; hence, a few breaks to minimize SS should be interjected throughout a VR task. For all task trials, we recorded the participant's travel trajectories to investigate each controller's intuitive utilization from a computed traversed distance. Shorter traversed distances indicated that participants intuitively utilized the TiltChair with a slower speed; while longer traversed distances indicated participants struggled to utilize the omni-directional treadmill with a unnaturalistic stimulation of gait. Therefore, VR navigation should use technologies best suited for the intended age group that minimizes SS, and produces intuitive interactions for the participants.

Detecting allocentric and egocentric navigation deficits in patients with schizophrenia and bipolar disorder using virtual reality.

PubMed

Mohammadi, Alireza; Hesami, Ehsan; Kargar, Mahmoud; Shams, Jamal

2018-04-01

Present evidence suggests that the use of virtual reality has great advantages in evaluating visuospatial navigation and memory for the diagnosis of psychiatric or other neurological disorders. There are a few virtual reality studies on allocentric and egocentric memories in schizophrenia, but studies on both memories in bipolar disorder are lacking. The objective of this study was to compare the performance of allocentric and egocentric memories in patients with schizophrenia and bipolar disorder. For this resolve, an advanced virtual reality navigation task (VRNT) was presented to distinguish the navigational performances of these patients. Twenty subjects with schizophrenia and 20 bipolar disorder patients were compared with 20 healthy-matched controls on the newly developed VRNT consisting of a virtual neighbourhood (allocentric memory) and a virtual maze (egocentric memory). The results demonstrated that schizophrenia patients were significantly impaired on all allocentric, egocentric, visual, and verbal memory tasks compared with patients with bipolar disorder and normal subjects. Dissimilarly, the performance of patients with bipolar disorder was slightly lower than that of control subjects in all these abilities, but no significant differences were observed. It was concluded that allocentric and egocentric navigation deficits are detectable in patients with schizophrenia and bipolar disorder using VRNT, and this task along with RAVLT and ROCFT can be used as a valid clinical tool for distinguishing these patients from normal subjects.

Neural Development Under Conditions of Spaceflight

NASA Technical Reports Server (NTRS)

Kosik, Kenneth S.; Steward, Oswald; Temple, Meredith D.; Denslow, Maria J.

2003-01-01

One of the key tasks the developing brain must learn is how to navigate within the environment. This skill depends on the brain's ability to establish memories of places and things in the environment so that it can form cognitive maps. Earth's gravity defines the plane of orientation of the spatial environment in which animals navigate, and cognitive maps are based on this plane of orientation. Given that experience during early development plays a key role in the development of other aspects of brain function, experience in a gravitational environment is likely to be essential for the proper organization of brain regions mediating learning and memory of spatial information. Since the hippocampus is the brain region responsible for cognitive mapping abilities, this study evaluated the development of hippocampal structure and function in rats that spent part of their early development in microgravity. Litters of male and female Sprague-Dawley rats were launched into space aboard the Space Shuttle Columbia on either postnatal day eight (P8) or 14 (P14) and remained in space for 16 days. Upon return to Earth, the rats were tested for their ability to remember spatial information and navigate using a variety of tests (the Morris water maze, a modified radial arm maze, and an open field apparatus). These rats were then tested physiologically to determine whether they exhibited normal synaptic plasticity in the hippocampus. In a separate group of rats (flight and controls), the hippocampus was analyzed using anatomical, molecular biological, and biochemical techniques immediately postlanding. There were remarkably few differences between the flight groups and their Earth-bound controls in either the navigation and spatial memory tasks or activity-induced synaptic plasticity. Microscopic and immunocytochemical analyses of the brain also did not reveal differences between flight animals and ground-based controls. These data suggest that, within the developmental window studied, microgravity has minimal long-term impact on cognitive mapping function and cellular substrates important for this function. Any differences due to development in microgravity were transient and returned to normal soon after return to Earth.

Navigation as a Source of Geometric Knowledge: Young Children's Use of Length, Angle, Distance, and Direction in a Reorientation Task

ERIC Educational Resources Information Center

Lee, Sang Ah; Sovrano, Valeria A.; Spelke, Elizabeth S.

2012-01-01

Geometry is one of the highest achievements of our species, but its foundations are obscure. Consistent with longstanding suggestions that geometrical knowledge is rooted in processes guiding navigation, the present study examines potential sources of geometrical knowledge in the navigation processes by which young children establish their sense…

a Schema for Extraction of Indoor Pedestrian Navigation Grid Network from Floor Plans

NASA Astrophysics Data System (ADS)

Niu, Lei; Song, Yiquan

2016-06-01

The requirement of the indoor navigation related tasks such emergency evacuation calls for efficient solutions for handling data sources. Therefore, the navigation grid extraction from existing floor plans draws attentions. To this, we have to thoroughly analyse the source data, such as Autocad dxf files. Then, we could establish a sounding navigation solution, which firstly complements the basic navigation rectangle boundaries, secondly subdivides these rectangles and finally generates accessible networks with these refined rectangles. Test files are introduced to validate the whole workflow and evaluate the solution performance. In conclusion, we have achieved the preliminary step of forming up accessible network from the navigation grids.

Development of a breast navigation program.

PubMed

Shockney, Lillie D; Haylock, Pamela J; Cantril, Cynthia

2013-05-01

To review the development of a navigation program in a major US academic health care institution, and provide guidance for navigation programmatic development in other settings. The Johns Hopkins Breast Center Steering Committee minutes, Hospital Cancer Registry; administrative data, and literature. Incorporating navigation services throughout the cancer continuum, from diagnosis to survivorship, provides guidance for patients with cancer. Navigation processes and programs must remain dynamic, reflecting patient and community needs. Oncology nurses have traditionally performed many tasks associated with navigation, including patient education, psychosocial support, and addressing barriers to care. This article provides an exemplar for nurses developing or enhancing comprehensive breast programs. Copyright © 2013 Elsevier Inc. All rights reserved.

Simulation-based camera navigation training in laparoscopy-a randomized trial.

PubMed

Nilsson, Cecilia; Sorensen, Jette Led; Konge, Lars; Westen, Mikkel; Stadeager, Morten; Ottesen, Bent; Bjerrum, Flemming

2017-05-01

Inexperienced operating assistants are often tasked with the important role of handling camera navigation during laparoscopic surgery. Incorrect handling can lead to poor visualization, increased operating time, and frustration for the operating surgeon-all of which can compromise patient safety. The objectives of this trial were to examine how to train laparoscopic camera navigation and to explore the transfer of skills to the operating room. A randomized, single-center superiority trial with three groups: The first group practiced simulation-based camera navigation tasks (camera group), the second group practiced performing a simulation-based cholecystectomy (procedure group), and the third group received no training (control group). Participants were surgical novices without prior laparoscopic experience. The primary outcome was assessment of camera navigation skills during a laparoscopic cholecystectomy. The secondary outcome was technical skills after training, using a previously developed model for testing camera navigational skills. The exploratory outcome measured participants' motivation toward the task as an operating assistant. Thirty-six participants were randomized. No significant difference was found in the primary outcome between the three groups (p = 0.279). The secondary outcome showed no significant difference between the interventions groups, total time 167 s (95% CI, 118-217) and 194 s (95% CI, 152-236) for the camera group and the procedure group, respectively (p = 0.369). Both interventions groups were significantly faster than the control group, 307 s (95% CI, 202-412), p = 0.018 and p = 0.045, respectively. On the exploratory outcome, the control group for two dimensions, interest/enjoyment (p = 0.030) and perceived choice (p = 0.033), had a higher score. Simulation-based training improves the technical skills required for camera navigation, regardless of practicing camera navigation or the procedure itself. Transfer to the clinical setting could, however, not be demonstrated. The control group demonstrated higher interest/enjoyment and perceived choice than the camera group.

76 FR 50667 - Regulated Navigation Area; Portsmouth Naval Shipyard, Portsmouth, NH

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-16

... provide for the safety of life on the navigable waters during ongoing ship construction. DATES: This rule.... ACTION: Temporary final rule. SUMMARY: The Coast Guard is establishing a regulated navigation area on the Piscataqua River near Portsmouth, NH. This temporary final rule places speed restrictions on all vessels...

A Virtual Object-Location Task for Children: Gender and Videogame Experience Influence Navigation; Age Impacts Memory and Completion Time.

PubMed

Rodriguez-Andres, David; Mendez-Lopez, Magdalena; Juan, M-Carmen; Perez-Hernandez, Elena

2018-01-01

The use of virtual reality-based tasks for studying memory has increased considerably. Most of the studies that have looked at child population factors that influence performance on such tasks have been focused on cognitive variables. However, little attention has been paid to the impact of non-cognitive skills. In the present paper, we tested 52 typically-developing children aged 5-12 years in a virtual object-location task. The task assessed their spatial short-term memory for the location of three objects in a virtual city. The virtual task environment was presented using a 3D application consisting of a 120″ stereoscopic screen and a gamepad interface. Measures of learning and displacement indicators in the virtual environment, 3D perception, satisfaction, and usability were obtained. We assessed the children's videogame experience, their visuospatial span, their ability to build blocks, and emotional and behavioral outcomes. The results indicate that learning improved with age. Significant effects on the speed of navigation were found favoring boys and those more experienced with videogames. Visuospatial skills correlated mainly with ability to recall object positions, but the correlation was weak. Longer paths were related with higher scores of withdrawal behavior, attention problems, and a lower visuospatial span. Aggressiveness and experience with the device used for interaction were related with faster navigation. However, the correlations indicated only weak associations among these variables.

Mathematical Tasks and the Student: Navigating "Tensions of Intentions" between Designers, Teachers, and Students

ERIC Educational Resources Information Center

Johnson, Heather Lynn; Coles, Alf; Clarke, David

2017-01-01

We articulate a student perspective on task design in mathematics education, foregrounding a dynamic relationship between intentions of task designers, teachers, and students. First, we characterize a student perspective on task design. Second, we provide theoretical perspectives that we use as tools to account for different facets of task design…

Facing the Maze: Young Cancer Survivors' Return to Education and Work-A Professional Expert Key Informant Study.

PubMed

Pedersen, Kaspar Jessen; Boisen, Kirsten Arntz; Midtgaard, Julie; Elsbernd, Abbey; Larsen, Hanne Baekgaard

2018-03-13

An insufficient transition to normal life after cancer treatment in adolescent and young adults (AYAs) may lead to decreased occupational and educational opportunities throughout a survivor's lifespan. Key informant interviews were used to access unique knowledge of the healthcare, educational, and social systems. We used key informant interviews with professionals representing disciplines from healthcare, educational, and social systems (n = 15). Informants were recruited through purposive sampling and snowball sampling. Interviews were analyzed thematically using Malterud's Systematic Text Condensation and verified by member checking. We found four major themes: the impact of late effects, navigating the system, social reintegration, and the drive of youth. Although legal frameworks are often in place to assist AYA cancer survivors, navigating the public, educational, and social systems is a complex task and many AYAs do not have the required skill set or energy. Furthermore, AYA survivors often feel different from their peers and misunderstood by their surroundings, which may hinder reintegration into normal social life. In Scandinavia, healthcare and education are free of charge with equal access for all, primarily funded by government taxes. Therefore, insurance status and tuition fees should not constitute barriers for returning to education and work. However, this study finds that the public and educational systems are complex to navigate, and that AYAs face trouble mobilizing the energy to receive needed support.

Planning paths to multiple targets: memory involvement and planning heuristics in spatial problem solving.

PubMed

Wiener, J M; Ehbauer, N N; Mallot, H A

2009-09-01

For large numbers of targets, path planning is a complex and computationally expensive task. Humans, however, usually solve such tasks quickly and efficiently. We present experiments studying human path planning performance and the cognitive processes and heuristics involved. Twenty-five places were arranged on a regular grid in a large room. Participants were repeatedly asked to solve traveling salesman problems (TSP), i.e., to find the shortest closed loop connecting a start location with multiple target locations. In Experiment 1, we tested whether humans employed the nearest neighbor (NN) strategy when solving the TSP. Results showed that subjects outperform the NN-strategy, suggesting that it is not sufficient to explain human route planning behavior. As a second possible strategy we tested a hierarchical planning heuristic in Experiment 2, demonstrating that participants first plan a coarse route on the region level that is refined during navigation. To test for the relevance of spatial working memory (SWM) and spatial long-term memory (LTM) for planning performance and the planning heuristics applied, we varied the memory demands between conditions in Experiment 2. In one condition the target locations were directly marked, such that no memory was required; a second condition required participants to memorize the target locations during path planning (SWM); in a third condition, additionally, the locations of targets had to retrieved from LTM (SWM and LTM). Results showed that navigation performance decreased with increasing memory demands while the dependence on the hierarchical planning heuristic increased.

78 FR 71495 - Regulated Navigation Area; Portsmouth Naval Shipyard, Piscataqua River, Portsmouth, NH

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-29

... rule is necessary to provide for the safety of life on the navigable waters during ongoing dive...: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast Guard is establishing a regulated navigation area (RNA) on the Piscataqua River near Portsmouth, NH. This temporary final rule places speed...

33 CFR 67.40-10 - Communication with owner.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Communication with owner. 67.40... Communication with owner. Communication with the owners of private aids to navigation by the District Commander shall be addressed to their usual or last known place of business, or to their local representative, if...

Conformal flight path symbology for head-up displays: Defining the distribution of visual attention in three-dimensional space

NASA Astrophysics Data System (ADS)

Ververs, Patricia May

An extensive investigation of the format for head-up display (HUD) instrumentation was conducted in a two-part experiment. First, a pilot's information requirements for the tasks of approach, landing, and taxi were determined through a survey administered to professional commercial pilots via the world wide web. The results of the survey were applied in the development of two symbology sets, one set for flight navigation and the second for ground navigation. Second, twenty pilots from the University of Illinois at Urbana-Champaign were recruited to participate in a 3-day experiment. The study was designed to investigate the format for symbology on HUDs and the performance effects of using conformal and partially conformal symbology to support the pilots' tasks. In addition, two different methods were investigated for supporting the pilots' transition between the task of flying and the task of landing. A seamless transition used visual momentum techniques to smoothly guide the pilots' cognitive transition between the serial displays and the associated tasks. A seamed approach employed an abrupt change between the displays to alert the pilots of the task switch. The results indicate that incorporating a virtually conformal, tunnel-in-the-sky symbology into a complete HUD instrumentation set offers promising pilot performance effects. Pilots easily navigated the complex curved approaches with little to no deviation from the flight path (approximately 10 feet), while performing the secondary tasks of the scanning their instruments and the environment. The seamless transition between the flight and ground symbology offered the pilots a preview of the upcoming landing task, thereby preparing them for the task switch. On the ground, the perspective (scene-linked) symbology set supported landing and taxi navigation tasks with the equal efficiency to the plan view display but with much greater precision. Theories of allocation of attention were used to interpret the experimental findings. Attention was found to be more widely distributed in X-Y space when the pilots were flying with the conformal, tunnel-in-the-sky as compared to the partially conformal ILS (instrument landing system) symbology set. There was little evidence that the air-based navigation displays were supporting divided attention in three-dimensional space. The ground-based scene-linked (truly conformal) display indicated promising effects of dividing attention in depth without negative consequences to processing the near domain symbology. Event expectancy was found to modulate pilot performance in the detection of events both on the symbology and in the environment. The phenomenon known as cognitive tunneling is discussed as a possible cause of the inadequate response times in resolving the anomalous events.

Action video game play and transfer of navigation and spatial cognition skills in adolescents who are blind.

PubMed

Connors, Erin C; Chrastil, Elizabeth R; Sánchez, Jaime; Merabet, Lotfi B

2014-01-01

For individuals who are blind, navigating independently in an unfamiliar environment represents a considerable challenge. Inspired by the rising popularity of video games, we have developed a novel approach to train navigation and spatial cognition skills in adolescents who are blind. Audio-based Environment Simulator (AbES) is a software application that allows for the virtual exploration of an existing building set in an action video game metaphor. Using this ludic-based approach to learning, we investigated the ability and efficacy of adolescents with early onset blindness to acquire spatial information gained from the exploration of a target virtual indoor environment. Following game play, participants were assessed on their ability to transfer and mentally manipulate acquired spatial information on a set of navigation tasks carried out in the real environment. Success in transfer of navigation skill performance was markedly high suggesting that interacting with AbES leads to the generation of an accurate spatial mental representation. Furthermore, there was a positive correlation between success in game play and navigation task performance. The role of virtual environments and gaming in the development of mental spatial representations is also discussed. We conclude that this game based learning approach can facilitate the transfer of spatial knowledge and further, can be used by individuals who are blind for the purposes of navigation in real-world environments.

Action video game play and transfer of navigation and spatial cognition skills in adolescents who are blind

PubMed Central

Connors, Erin C.; Chrastil, Elizabeth R.; Sánchez, Jaime; Merabet, Lotfi B.

2014-01-01

For individuals who are blind, navigating independently in an unfamiliar environment represents a considerable challenge. Inspired by the rising popularity of video games, we have developed a novel approach to train navigation and spatial cognition skills in adolescents who are blind. Audio-based Environment Simulator (AbES) is a software application that allows for the virtual exploration of an existing building set in an action video game metaphor. Using this ludic-based approach to learning, we investigated the ability and efficacy of adolescents with early onset blindness to acquire spatial information gained from the exploration of a target virtual indoor environment. Following game play, participants were assessed on their ability to transfer and mentally manipulate acquired spatial information on a set of navigation tasks carried out in the real environment. Success in transfer of navigation skill performance was markedly high suggesting that interacting with AbES leads to the generation of an accurate spatial mental representation. Furthermore, there was a positive correlation between success in game play and navigation task performance. The role of virtual environments and gaming in the development of mental spatial representations is also discussed. We conclude that this game based learning approach can facilitate the transfer of spatial knowledge and further, can be used by individuals who are blind for the purposes of navigation in real-world environments. PMID:24653690

Domain-Specific Interference Tests on Navigational Working Memory in Military Pilots.

PubMed

Verde, Paola; Boccia, Maddalena; Colangeli, Stefano; Barbetti, Sonia; Nori, Raffaella; Ferlazzo, Fabio; Piccolo, Francesco; Vitalone, Roberto; Lucertini, Elena; Piccardi, Laura

2016-06-01

Human navigation is a very complex ability that encompasses all four stages of human information processing (sensory input, perception/cognition, selection, and execution of an action), involving both cognitive and physical requirements. During flight, the pilot uses all of these stages and one of the most critical aspect is interference. In fact, spatial tasks competing for the same cognitive resource cause greater distraction from a concurrent task than another task that uses different resource modalities. Here we compared and contrasted the performance of pilots and nonpilots of both genders performing increasingly complex navigational memory tasks while exposed to various forms of interference. We investigated the effects of four different sources of interference: motor, spatial motor, verbal, and spatial environment, focusing on gender differences. We found that flight experts perform better than controls (Pilots: 6.50 ± 1.29; Nonpilots: 5.45 ± 1.41). Furthermore, in the general population, navigational working memory is compromised only by spatial environmental interference (Nonpilots: 4.52 ± 1.50); female nonpilots were less able than male nonpilots. Also, the flight expert group showed the same interference, even if reduced (Pilots: 5.24 ± 0.92); moreover, we highlighted a complete absence of gender-related effects. Spatial environmental interference is the only interference producing a decrease in performance. Nevertheless, pilots are less affected than the general population. This is probably a consequence of the need to commit substantial cognitive resources to process spatial information during flight.

Specificity and Transfer in Learning How to Follow Navigation Instructions

NASA Technical Reports Server (NTRS)

Healy, Alice F.; Schneider, Vivian L.; Barshi, Immanuel

2012-01-01

We report a series of experiments that use a navigation task in which instructions for navigating in a space displayed as grids on a computer screen are given to subjects who then attempt to follow them by mouse clicking on the grids. The navigation task was broken down into component dimensions (e.g., presentation mode of the instructions, length of the instructions, characteristics of the display, size of the grids, response type). For each task dimension, one condition was used at training and the same or another condition was used at test. Each task dimension was examined in terms of two measures. One measure provided an index of transfer (i.e., better performance at test than at training when test and training involved different conditions), and the other provided an index of specificity (i.e., better performance at test when training and test conditions were the same than when training and test conditions were different). By and large, these two indices were complementary, so there was evidence of either transfer or specificity but not both. For one dimension transfer but no specificity was evident, and for another dimension specificity but no transfer was evident. For the remaining dimensions, however, there was asymmetrical transfer, with transfer evident for some conditions and specificity evident for others. The findings are interpreted within the procedural reinstatement framework. They have practical implications concerning how to optimize training and how much fidelity to the testing situation is necessary when training.

The role of the hippocampus in navigation is memory

PubMed Central

2017-01-01

There is considerable research on the neurobiological mechanisms within the hippocampal system that support spatial navigation. In this article I review the literature on navigational strategies in humans and animals, observations on hippocampal function in navigation, and studies of hippocampal neural activity in animals and humans performing different navigational tasks and tests of memory. Whereas the hippocampus is essential to spatial navigation via a cognitive map, its role derives from the relational organization and flexibility of cognitive maps and not from a selective role in the spatial domain. Correspondingly, hippocampal networks map multiple navigational strategies, as well as other spatial and nonspatial memories and knowledge domains that share an emphasis on relational organization. These observations suggest that the hippocampal system is not dedicated to spatial cognition and navigation, but organizes experiences in memory, for which spatial mapping and navigation are both a metaphor for and a prominent application of relational memory organization. PMID:28148640

Model-based software engineering for an optical navigation system for spacecraft

NASA Astrophysics Data System (ADS)

Franz, T.; Lüdtke, D.; Maibaum, O.; Gerndt, A.

2017-09-01

The project Autonomous Terrain-based Optical Navigation (ATON) at the German Aerospace Center (DLR) is developing an optical navigation system for future landing missions on celestial bodies such as the moon or asteroids. Image data obtained by optical sensors can be used for autonomous determination of the spacecraft's position and attitude. Camera-in-the-loop experiments in the Testbed for Robotic Optical Navigation (TRON) laboratory and flight campaigns with unmanned aerial vehicle (UAV) are performed to gather flight data for further development and to test the system in a closed-loop scenario. The software modules are executed in the C++ Tasking Framework that provides the means to concurrently run the modules in separated tasks, send messages between tasks, and schedule task execution based on events. Since the project is developed in collaboration with several institutes in different domains at DLR, clearly defined and well-documented interfaces are necessary. Preventing misconceptions caused by differences between various development philosophies and standards turned out to be challenging. After the first development cycles with manual Interface Control Documents (ICD) and manual implementation of the complex interactions between modules, we switched to a model-based approach. The ATON model covers a graphical description of the modules, their parameters and communication patterns. Type and consistency checks on this formal level help to reduce errors in the system. The model enables the generation of interfaces and unified data types as well as their documentation. Furthermore, the C++ code for the exchange of data between the modules and the scheduling of the software tasks is created automatically. With this approach, changing the data flow in the system or adding additional components (e.g., a second camera) have become trivial.

Model-based software engineering for an optical navigation system for spacecraft

NASA Astrophysics Data System (ADS)

Franz, T.; Lüdtke, D.; Maibaum, O.; Gerndt, A.

2018-06-01

The project Autonomous Terrain-based Optical Navigation (ATON) at the German Aerospace Center (DLR) is developing an optical navigation system for future landing missions on celestial bodies such as the moon or asteroids. Image data obtained by optical sensors can be used for autonomous determination of the spacecraft's position and attitude. Camera-in-the-loop experiments in the Testbed for Robotic Optical Navigation (TRON) laboratory and flight campaigns with unmanned aerial vehicle (UAV) are performed to gather flight data for further development and to test the system in a closed-loop scenario. The software modules are executed in the C++ Tasking Framework that provides the means to concurrently run the modules in separated tasks, send messages between tasks, and schedule task execution based on events. Since the project is developed in collaboration with several institutes in different domains at DLR, clearly defined and well-documented interfaces are necessary. Preventing misconceptions caused by differences between various development philosophies and standards turned out to be challenging. After the first development cycles with manual Interface Control Documents (ICD) and manual implementation of the complex interactions between modules, we switched to a model-based approach. The ATON model covers a graphical description of the modules, their parameters and communication patterns. Type and consistency checks on this formal level help to reduce errors in the system. The model enables the generation of interfaces and unified data types as well as their documentation. Furthermore, the C++ code for the exchange of data between the modules and the scheduling of the software tasks is created automatically. With this approach, changing the data flow in the system or adding additional components (e.g., a second camera) have become trivial.

Navigation experience and mental representations of the environment: do pilots build better cognitive maps?

PubMed

Sutton, Jennifer E; Buset, Melanie; Keller, Mikayla

2014-01-01

A number of careers involve tasks that place demands on spatial cognition, but it is still unclear how and whether skills acquired in such applied experiences transfer to other spatial tasks. The current study investigated the association between pilot training and the ability to form a mental survey representation, or cognitive map, of a novel, ground-based, virtual environment. Undergraduate students who were engaged in general aviation pilot training and controls matched to the pilots on gender and video game usage freely explored a virtual town. Subsequently, participants performed a direction estimation task that tested the accuracy of their cognitive map representation of the town. In addition, participants completed the Object Perspective Test and rated their spatial abilities. Pilots were significantly more accurate than controls at estimating directions but did not differ from controls on the Object Perspective Test. Locations in the town were visited at a similar rate by the two groups, indicating that controls' relatively lower accuracy was not due to failure to fully explore the town. Pilots' superior performance is likely due to better online cognitive processing during exploration, suggesting the spatial updating they engage in during flight transfers to a non-aviation context.

Navigation Experience and Mental Representations of the Environment: Do Pilots Build Better Cognitive Maps?

PubMed Central

Sutton, Jennifer E.; Buset, Melanie; Keller, Mikayla

2014-01-01

A number of careers involve tasks that place demands on spatial cognition, but it is still unclear how and whether skills acquired in such applied experiences transfer to other spatial tasks. The current study investigated the association between pilot training and the ability to form a mental survey representation, or cognitive map, of a novel, ground-based, virtual environment. Undergraduate students who were engaged in general aviation pilot training and controls matched to the pilots on gender and video game usage freely explored a virtual town. Subsequently, participants performed a direction estimation task that tested the accuracy of their cognitive map representation of the town. In addition, participants completed the Object Perspective Test and rated their spatial abilities. Pilots were significantly more accurate than controls at estimating directions but did not differ from controls on the Object Perspective Test. Locations in the town were visited at a similar rate by the two groups, indicating that controls' relatively lower accuracy was not due to failure to fully explore the town. Pilots' superior performance is likely due to better online cognitive processing during exploration, suggesting the spatial updating they engage in during flight transfers to a non-aviation context. PMID:24603608

Learning Long-Range Vision for an Offroad Robot

DTIC Science & Technology

2008-09-01

robot to perceive and navigate in an unstructured natural world is a difficult task. Without learning, navigation systems are short-range and extremely...unsupervised or weakly supervised learning methods are necessary for training general feature representations for natural scenes. The process was...the world looked dark, and Legos when I was weary. iii ABSTRACT Teaching a robot to perceive and navigate in an unstructured natural world is a

Data management of Shuttle radiofrequency navigation aids

NASA Technical Reports Server (NTRS)

Stokes, R. E.; Presser, P.

1982-01-01

It is noted that the Shuttle navigation system employs redundant tactical air navigation (tacan) and microwave scanning beam landing system (MSBLS) equipment for use in navigation during descent from altitudes of about 150,000 feet through rollout. Attention is given here to the multiple tacan and MSBLS units (three each) that were placed onboard to provide the necessary protection in the event of possible failures. The goals, features, approach, and performance of onboard software required to manage multiple tacan MSBLS units and to provide the corresponding data for navigation processing are described.

Enhancing Navigation Skills through Audio Gaming.

PubMed

Sánchez, Jaime; Sáenz, Mauricio; Pascual-Leone, Alvaro; Merabet, Lotfi

2010-01-01

We present the design, development and initial cognitive evaluation of an Audio-based Environment Simulator (AbES). This software allows a blind user to navigate through a virtual representation of a real space for the purposes of training orientation and mobility skills. Our findings indicate that users feel satisfied and self-confident when interacting with the audio-based interface, and the embedded sounds allow them to correctly orient themselves and navigate within the virtual world. Furthermore, users are able to transfer spatial information acquired through virtual interactions into real world navigation and problem solving tasks.

Enhancing Navigation Skills through Audio Gaming

PubMed Central

Sánchez, Jaime; Sáenz, Mauricio; Pascual-Leone, Alvaro; Merabet, Lotfi

2014-01-01

We present the design, development and initial cognitive evaluation of an Audio-based Environment Simulator (AbES). This software allows a blind user to navigate through a virtual representation of a real space for the purposes of training orientation and mobility skills. Our findings indicate that users feel satisfied and self-confident when interacting with the audio-based interface, and the embedded sounds allow them to correctly orient themselves and navigate within the virtual world. Furthermore, users are able to transfer spatial information acquired through virtual interactions into real world navigation and problem solving tasks. PMID:25505796

Navigation in Grid Space with the NAS Grid Benchmarks

NASA Technical Reports Server (NTRS)

Frumkin, Michael; Hood, Robert; Biegel, Bryan A. (Technical Monitor)

2002-01-01

We present a navigational tool for computational grids. The navigational process is based on measuring the grid characteristics with the NAS Grid Benchmarks (NGB) and using the measurements to assign tasks of a grid application to the grid machines. The tool allows the user to explore the grid space and to navigate the execution at a grid application to minimize its turnaround time. We introduce the notion of gridscape as a user view of the grid and show how it can be me assured by NGB, Then we demonstrate how the gridscape can be used with two different schedulers to navigate a grid application through a rudimentary grid.

LED display for solo aircraft instrument navigation

NASA Technical Reports Server (NTRS)

Crouch, R. K.; Kelly, W. L., VI; Lina, L. J.; Meredith, B. D.

1979-01-01

Solo pilot's task is made easier through convenient display of landing and navigation data. Use of display shows promise as more efficient means of presenting sequential instructions and data, such as course heading, altitude, and radio frequency, to minimize pilot's workload during solo instrument flight.

Indoor Navigation by People with Visual Impairment Using a Digital Sign System

PubMed Central

Legge, Gordon E.; Beckmann, Paul J.; Tjan, Bosco S.; Havey, Gary; Kramer, Kevin; Rolkosky, David; Gage, Rachel; Chen, Muzi; Puchakayala, Sravan; Rangarajan, Aravindhan

2013-01-01

There is a need for adaptive technology to enhance indoor wayfinding by visually-impaired people. To address this need, we have developed and tested a Digital Sign System. The hardware and software consist of digitally-encoded signs widely distributed throughout a building, a handheld sign-reader based on an infrared camera, image-processing software, and a talking digital map running on a mobile device. Four groups of subjects—blind, low vision, blindfolded sighted, and normally sighted controls—were evaluated on three navigation tasks. The results demonstrate that the technology can be used reliably in retrieving information from the signs during active mobility, in finding nearby points of interest, and following routes in a building from a starting location to a destination. The visually impaired subjects accurately and independently completed the navigation tasks, but took substantially longer than normally sighted controls. This fully functional prototype system demonstrates the feasibility of technology enabling independent indoor navigation by people with visual impairment. PMID:24116156

Assistive obstacle detection and navigation devices for vision-impaired users.

PubMed

Ong, S K; Zhang, J; Nee, A Y C

2013-09-01

Quality of life for the visually impaired is an urgent worldwide issue that needs to be addressed. Obstacle detection is one of the most important navigation tasks for the visually impaired. In this research, a novel range sensor placement scheme is proposed in this paper for the development of obstacle detection devices. Based on this scheme, two prototypes have been developed targeting at different user groups. This paper discusses the design issues, functional modules and the evaluation tests carried out for both prototypes. Implications for Rehabilitation Visual impairment problem is becoming more severe due to the worldwide ageing population. Individuals with visual impairment require assistance from assistive devices in daily navigation tasks. Traditional assistive devices that assist navigation may have certain drawbacks, such as the limited sensing range of a white cane. Obstacle detection devices applying the range sensor technology can identify road conditions with a higher sensing range to notify the users of potential dangers in advance.

A Virtual Object-Location Task for Children: Gender and Videogame Experience Influence Navigation; Age Impacts Memory and Completion Time

PubMed Central

Rodriguez-Andres, David; Mendez-Lopez, Magdalena; Juan, M.-Carmen; Perez-Hernandez, Elena

2018-01-01

The use of virtual reality-based tasks for studying memory has increased considerably. Most of the studies that have looked at child population factors that influence performance on such tasks have been focused on cognitive variables. However, little attention has been paid to the impact of non-cognitive skills. In the present paper, we tested 52 typically-developing children aged 5–12 years in a virtual object-location task. The task assessed their spatial short-term memory for the location of three objects in a virtual city. The virtual task environment was presented using a 3D application consisting of a 120″ stereoscopic screen and a gamepad interface. Measures of learning and displacement indicators in the virtual environment, 3D perception, satisfaction, and usability were obtained. We assessed the children’s videogame experience, their visuospatial span, their ability to build blocks, and emotional and behavioral outcomes. The results indicate that learning improved with age. Significant effects on the speed of navigation were found favoring boys and those more experienced with videogames. Visuospatial skills correlated mainly with ability to recall object positions, but the correlation was weak. Longer paths were related with higher scores of withdrawal behavior, attention problems, and a lower visuospatial span. Aggressiveness and experience with the device used for interaction were related with faster navigation. However, the correlations indicated only weak associations among these variables. PMID:29674988

An Accumulation-of-Evidence Task Using Visual Pulses for Mice Navigating in Virtual Reality

PubMed Central

Pinto, Lucas; Koay, Sue A.; Engelhard, Ben; Yoon, Alice M.; Deverett, Ben; Thiberge, Stephan Y.; Witten, Ilana B.; Tank, David W.; Brody, Carlos D.

2018-01-01

The gradual accumulation of sensory evidence is a crucial component of perceptual decision making, but its neural mechanisms are still poorly understood. Given the wide availability of genetic and optical tools for mice, they can be useful model organisms for the study of these phenomena; however, behavioral tools are largely lacking. Here, we describe a new evidence-accumulation task for head-fixed mice navigating in a virtual reality (VR) environment. As they navigate down the stem of a virtual T-maze, they see brief pulses of visual evidence on either side, and retrieve a reward on the arm with the highest number of pulses. The pulses occur randomly with Poisson statistics, yielding a diverse yet well-controlled stimulus set, making the data conducive to a variety of computational approaches. A large number of mice of different genotypes were able to learn and consistently perform the task, at levels similar to rats in analogous tasks. They are sensitive to side differences of a single pulse, and their memory of the cues is stable over time. Moreover, using non-parametric as well as modeling approaches, we show that the mice indeed accumulate evidence: they use multiple pulses of evidence from throughout the cue region of the maze to make their decision, albeit with a small overweighting of earlier cues, and their performance is affected by the magnitude but not the duration of evidence. Additionally, analysis of the mice's running patterns revealed that trajectories are fairly stereotyped yet modulated by the amount of sensory evidence, suggesting that the navigational component of this task may provide a continuous readout correlated to the underlying cognitive variables. Our task, which can be readily integrated with state-of-the-art techniques, is thus a valuable tool to study the circuit mechanisms and dynamics underlying perceptual decision making, particularly under more complex behavioral contexts. PMID:29559900

Navigation by environmental geometry: the use of zebrafish as a model.

PubMed

Lee, Sang Ah; Vallortigara, Giorgio; Flore, Michele; Spelke, Elizabeth S; Sovrano, Valeria A

2013-10-01

Sensitivity to environmental shape in spatial navigation has been found, at both behavioural and neural levels, in virtually every species tested, starting early in development. Moreover, evidence that genetic deletions can cause selective deficits in such navigation behaviours suggests a genetic basis to navigation by environmental geometry. Nevertheless, the geometric computations underlying navigation have not been specified in any species. The present study teases apart the geometric components within the traditionally used rectangular enclosure and finds that zebrafish selectively represent distance and directional relationships between extended boundary surfaces. Similar behavioural results in geometric navigation tasks with human children provide prima facie evidence for similar underlying cognitive computations and open new doors for probing the genetic foundations that give rise to these computations.

Human-Robot Interaction

NASA Technical Reports Server (NTRS)

Sandor, Aniko; Cross, E. Vincent, II; Chang, Mai Lee

2015-01-01

Human-robot interaction (HRI) is a discipline investigating the factors affecting the interactions between humans and robots. It is important to evaluate how the design of interfaces affect the human's ability to perform tasks effectively and efficiently when working with a robot. By understanding the effects of interface design on human performance, workload, and situation awareness, interfaces can be developed to appropriately support the human in performing tasks with minimal errors and with appropriate interaction time and effort. Thus, the results of research on human-robot interfaces have direct implications for the design of robotic systems. For efficient and effective remote navigation of a rover, a human operator needs to be aware of the robot's environment. However, during teleoperation, operators may get information about the environment only through a robot's front-mounted camera causing a keyhole effect. The keyhole effect reduces situation awareness which may manifest in navigation issues such as higher number of collisions, missing critical aspects of the environment, or reduced speed. One way to compensate for the keyhole effect and the ambiguities operators experience when they teleoperate a robot is adding multiple cameras and including the robot chassis in the camera view. Augmented reality, such as overlays, can also enhance the way a person sees objects in the environment or in camera views by making them more visible. Scenes can be augmented with integrated telemetry, procedures, or map information. Furthermore, the addition of an exocentric (i.e., third-person) field of view from a camera placed in the robot's environment may provide operators with the additional information needed to gain spatial awareness of the robot. Two research studies investigated possible mitigation approaches to address the keyhole effect: 1) combining the inclusion of the robot chassis in the camera view with augmented reality overlays, and 2) modifying the camera frame of reference. The first study investigated the effects of inclusion and exclusion of the robot chassis along with superimposing a simple arrow overlay onto the video feed of operator task performance during teleoperation of a mobile robot in a driving task. In this study, the front half of the robot chassis was made visible through the use of three cameras, two side-facing and one forward-facing. The purpose of the second study was to compare operator performance when teleoperating a robot from an egocentric-only and combined (egocentric plus exocentric camera) view. Camera view parameters that are found to be beneficial in these laboratory experiments can be implemented on NASA rovers and tested in a real-world driving and navigation scenario on-site at the Johnson Space Center.

Shape Perception and Navigation in Blind Adults

PubMed Central

Gori, Monica; Cappagli, Giulia; Baud-Bovy, Gabriel; Finocchietti, Sara

2017-01-01

Different sensory systems interact to generate a representation of space and to navigate. Vision plays a critical role in the representation of space development. During navigation, vision is integrated with auditory and mobility cues. In blind individuals, visual experience is not available and navigation therefore lacks this important sensory signal. In blind individuals, compensatory mechanisms can be adopted to improve spatial and navigation skills. On the other hand, the limitations of these compensatory mechanisms are not completely clear. Both enhanced and impaired reliance on auditory cues in blind individuals have been reported. Here, we develop a new paradigm to test both auditory perception and navigation skills in blind and sighted individuals and to investigate the effect that visual experience has on the ability to reproduce simple and complex paths. During the navigation task, early blind, late blind and sighted individuals were required first to listen to an audio shape and then to recognize and reproduce it by walking. After each audio shape was presented, a static sound was played and the participants were asked to reach it. Movements were recorded with a motion tracking system. Our results show three main impairments specific to early blind individuals. The first is the tendency to compress the shapes reproduced during navigation. The second is the difficulty to recognize complex audio stimuli, and finally, the third is the difficulty in reproducing the desired shape: early blind participants occasionally reported perceiving a square but they actually reproduced a circle during the navigation task. We discuss these results in terms of compromised spatial reference frames due to lack of visual input during the early period of development. PMID:28144226

Visual Place Learning in Drosophila melanogaster

PubMed Central

Ofstad, Tyler A.; Zuker, Charles S.; Reiser, Michael B.

2011-01-01

The ability of insects to learn and navigate to specific locations in the environment has fascinated naturalists for decades. While the impressive navigation abilities of ants, bees, wasps, and other insects clearly demonstrate that insects are capable of visual place learning1–4, little is known about the underlying neural circuits that mediate these behaviors. Drosophila melanogaster is a powerful model organism for dissecting the neural circuitry underlying complex behaviors, from sensory perception to learning and memory. Flies can identify and remember visual features such as size, color, and contour orientation5, 6. However, the extent to which they use vision to recall specific locations remains unclear. Here we describe a visual place-learning platform and demonstrate that Drosophila are capable of forming and retaining visual place memories to guide selective navigation. By targeted genetic silencing of small subsets of cells in the Drosophila brain we show that neurons in the ellipsoid body, but not in the mushroom bodies, are necessary for visual place learning. Together, these studies reveal distinct neuroanatomical substrates for spatial versus non-spatial learning, and substantiate Drosophila as a powerful model for the study of spatial memories. PMID:21654803

Convolutional Neural Network-Based Robot Navigation Using Uncalibrated Spherical Images †

PubMed Central

Ran, Lingyan; Zhang, Yanning; Zhang, Qilin; Yang, Tao

2017-01-01

Vision-based mobile robot navigation is a vibrant area of research with numerous algorithms having been developed, the vast majority of which either belong to the scene-oriented simultaneous localization and mapping (SLAM) or fall into the category of robot-oriented lane-detection/trajectory tracking. These methods suffer from high computational cost and require stringent labelling and calibration efforts. To address these challenges, this paper proposes a lightweight robot navigation framework based purely on uncalibrated spherical images. To simplify the orientation estimation, path prediction and improve computational efficiency, the navigation problem is decomposed into a series of classification tasks. To mitigate the adverse effects of insufficient negative samples in the “navigation via classification” task, we introduce the spherical camera for scene capturing, which enables 360° fisheye panorama as training samples and generation of sufficient positive and negative heading directions. The classification is implemented as an end-to-end Convolutional Neural Network (CNN), trained on our proposed Spherical-Navi image dataset, whose category labels can be efficiently collected. This CNN is capable of predicting potential path directions with high confidence levels based on a single, uncalibrated spherical image. Experimental results demonstrate that the proposed framework outperforms competing ones in realistic applications. PMID:28604624

Convolutional Neural Network-Based Robot Navigation Using Uncalibrated Spherical Images.

PubMed

Ran, Lingyan; Zhang, Yanning; Zhang, Qilin; Yang, Tao

2017-06-12

Vision-based mobile robot navigation is a vibrant area of research with numerous algorithms having been developed, the vast majority of which either belong to the scene-oriented simultaneous localization and mapping (SLAM) or fall into the category of robot-oriented lane-detection/trajectory tracking. These methods suffer from high computational cost and require stringent labelling and calibration efforts. To address these challenges, this paper proposes a lightweight robot navigation framework based purely on uncalibrated spherical images. To simplify the orientation estimation, path prediction and improve computational efficiency, the navigation problem is decomposed into a series of classification tasks. To mitigate the adverse effects of insufficient negative samples in the "navigation via classification" task, we introduce the spherical camera for scene capturing, which enables 360° fisheye panorama as training samples and generation of sufficient positive and negative heading directions. The classification is implemented as an end-to-end Convolutional Neural Network (CNN), trained on our proposed Spherical-Navi image dataset, whose category labels can be efficiently collected. This CNN is capable of predicting potential path directions with high confidence levels based on a single, uncalibrated spherical image. Experimental results demonstrate that the proposed framework outperforms competing ones in realistic applications.

Finding the Fortunate Islands and Other Astrolabe Tricks of Early Astronomical Navigation

NASA Astrophysics Data System (ADS)

Lattis, James

2007-12-01

Explorers of the late 16th and early 17th centuries had at their disposal a very limited set of tools and techniques useful for astronomical navigation. At least one author, Christoph Clavius, saw the traditional planispheric astrolabe as an important adjunct for mapping, navigation, and other tasks useful in an age of exploration. This paper will explain some of the applications Clavius recommends and evaluate some of their important limitations.

Design of a laser navigation system for the inspection robot used in substation

NASA Astrophysics Data System (ADS)

Zhu, Jing; Sun, Yanhe; Sun, Deli

2017-01-01

Aimed at the deficiency of the magnetic guide and RFID parking system used by substation inspection robot now, a laser navigation system is designed, and the system structure, the method of map building and positioning are all introduced. The system performance is tested in a 500kV substation, and the result show that the repetitive precision of navigation system is precise enough to help the robot fulfill inspection tasks.

Field test designs for the evaluation of vessel operators' use of and confidence in various aids to navigation

DOT National Transportation Integrated Search

1995-12-01

Development Center in evaluating current Coast Guard policies and development plans for : Waterways Management, a "Waterways Management Research and Planning" task plan was : established as Task Area A in FY '94. The purpose of this task area is to d...

Coding of navigational affordances in the human visual system

PubMed Central

Epstein, Russell A.

2017-01-01

A central component of spatial navigation is determining where one can and cannot go in the immediate environment. We used fMRI to test the hypothesis that the human visual system solves this problem by automatically identifying the navigational affordances of the local scene. Multivoxel pattern analyses showed that a scene-selective region of dorsal occipitoparietal cortex, known as the occipital place area, represents pathways for movement in scenes in a manner that is tolerant to variability in other visual features. These effects were found in two experiments: One using tightly controlled artificial environments as stimuli, the other using a diverse set of complex, natural scenes. A reconstruction analysis demonstrated that the population codes of the occipital place area could be used to predict the affordances of novel scenes. Taken together, these results reveal a previously unknown mechanism for perceiving the affordance structure of navigable space. PMID:28416669

HH-65A Dolphin digital integrated avionics

NASA Technical Reports Server (NTRS)

Huntoon, R. B.

1984-01-01

Communication, navigation, flight control, and search sensor management are avionics functions which constitute every Search and Rescue (SAR) operation. Routine cockpit duties monopolize crew attention during SAR operations and thus impair crew effectiveness. The United States Coast Guard challenged industry to build an avionics system that automates routine tasks and frees the crew to focus on the mission tasks. The HH-64A SAR avionics systems of communication, navigation, search sensors, and flight control have existed independently. On the SRR helicopter, the flight management system (FMS) was introduced. H coordinates or integrates these functions. The pilot interacts with the FMS rather than the individual subsystems, using simple, straightforward procedures to address distinct mission tasks and the flight management system, in turn, orchestrates integrated system response.

The Mathematics of Navigating the Solar System

NASA Technical Reports Server (NTRS)

Hintz, Gerald

2000-01-01

In navigating spacecraft throughout the solar system, the space navigator relies on three academic disciplines - optimization, estimation, and control - that work on mathematical models of the real world. Thus, the navigator determines the flight path that will consume propellant and other resources in an efficient manner, determines where the craft is and predicts where it will go, and transfers it onto the optimal trajectory that meets operational and mission constraints. Mission requirements, for example, demand that observational measurements be made with sufficient precision that relativity must be modeled in collecting and fitting (the estimation process) the data, and propagating the trajectory. Thousands of parameters are now determined in near real-time to model the gravitational forces acting on a spacecraft in the vicinity of an irregularly shaped body. Completing these tasks requires mathematical models, analyses, and processing techniques. Newton, Gauss, Lambert, Legendre, and others are justly famous for their contributions to the mathematics of these tasks. More recently, graduate students participated in research to update the gravity model of the Saturnian system, including higher order gravity harmonics, tidal effects, and the influence of the rings. This investigation was conducted for the Cassini project to incorporate new trajectory modeling features in the navigation software. The resulting trajectory model will be used in navigating the 4-year tour of the Saturnian satellites. Also, undergraduate students are determining the ephemerides (locations versus time) of asteroids that will be used as reference objects in navigating the New Millennium's Deep Space 1 spacecraft autonomously.

Virtual water maze learning in human increases functional connectivity between posterior hippocampus and dorsal caudate.

PubMed

Woolley, Daniel G; Mantini, Dante; Coxon, James P; D'Hooge, Rudi; Swinnen, Stephan P; Wenderoth, Nicole

2015-04-01

Recent work has demonstrated that functional connectivity between remote brain regions can be modulated by task learning or the performance of an already well-learned task. Here, we investigated the extent to which initial learning and stable performance of a spatial navigation task modulates functional connectivity between subregions of hippocampus and striatum. Subjects actively navigated through a virtual water maze environment and used visual cues to learn the position of a fixed spatial location. Resting-state functional magnetic resonance imaging scans were collected before and after virtual water maze navigation in two scan sessions conducted 1 week apart, with a behavior-only training session in between. There was a large significant reduction in the time taken to intercept the target location during scan session 1 and a small significant reduction during the behavior-only training session. No further reduction was observed during scan session 2. This indicates that scan session 1 represented initial learning and scan session 2 represented stable performance. We observed an increase in functional connectivity between left posterior hippocampus and left dorsal caudate that was specific to scan session 1. Importantly, the magnitude of the increase in functional connectivity was correlated with offline gains in task performance. Our findings suggest cooperative interaction occurs between posterior hippocampus and dorsal caudate during awake rest following the initial phase of spatial navigation learning. Furthermore, we speculate that the increase in functional connectivity observed during awake rest after initial learning might reflect consolidation-related processing. © 2014 Wiley Periodicals, Inc.

Three-dimensional virtual navigation versus conventional image guidance: A randomized controlled trial.

PubMed

Dixon, Benjamin J; Chan, Harley; Daly, Michael J; Qiu, Jimmy; Vescan, Allan; Witterick, Ian J; Irish, Jonathan C

2016-07-01

Providing image guidance in a 3-dimensional (3D) format, visually more in keeping with the operative field, could potentially reduce workload and lead to faster and more accurate navigation. We wished to assess a 3D virtual-view surgical navigation prototype in comparison to a traditional 2D system. Thirty-seven otolaryngology surgeons and trainees completed a randomized crossover navigation exercise on a cadaver model. Each subject identified three sinonasal landmarks with 3D virtual (3DV) image guidance and three landmarks with conventional cross-sectional computed tomography (CT) image guidance. Subjects were randomized with regard to which side and display type was tested initially. Accuracy, task completion time, and task workload were recorded. Display type did not influence accuracy (P > 0.2) or efficiency (P > 0.3) for any of the six landmarks investigated. Pooled landmark data revealed a trend of improved accuracy in the 3DV group by 0.44 millimeters (95% confidence interval [0.00-0.88]). High-volume surgeons were significantly faster (P < 0.01) and had reduced workload scores in all domains (P < 0.01), but they were no more accurate (P > 0.28). Real-time 3D image guidance did not influence accuracy, efficiency, or task workload when compared to conventional triplanar image guidance. The subtle pooled accuracy advantage for the 3DV view is unlikely to be of clinical significance. Experience level was strongly correlated to task completion time and workload but did not influence accuracy. N/A. Laryngoscope, 126:1510-1515, 2016. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

Navigating Cultural Worlds and Negotiating Identities: A Conceptual Model

ERIC Educational Resources Information Center

Mistry, Jayanthi; Wu, Jean

2010-01-01

For children from culturally and linguistically diverse backgrounds the ability to maintain flexible identities and integrate multiple facets of self is a crucial developmental task. We present a conceptual model for the development of expertise in navigating across cultures, delineating how community characteristics interact with family and…

Does Navigation Improve Accuracy of Placement of Pedicle Screws in Single-level Lumbar Degenerative Spondylolisthesis?: A Comparison Between Free-hand and Three-dimensional O-Arm Navigation Techniques.

PubMed

Boon Tow, Benjamin Phak; Yue, Wai Mun; Srivastava, Abhishek; Lai, Jenn Ming; Guo, Chang Ming; Wearn Peng, Benedict Chan; Chen, John L T; Yew, Andy K S; Seng, Chusheng; Tan, Seang Beng

2015-10-01

This was a prospective, nonrandomized study. To assess the accuracy of O-arm navigation-based pedicle screw insertion in lumbar degenerative spondylolisthesis and to compare it with free-hand pedicle screw insertion technique in matched population. O-arm navigation is latest in navigation technology that can provide real-time intraoperative images in 3 dimensions while placing the pedicle screws to improve intraoperative pedicle screw accuracy. Degenerative lumbar spondylolisthesis is a locally unstable pathology and placement of pedicle screws can cause increased rotation and translation of the vertebral body. However, is this motion detected by the tracker placed across the unstable segment, is a matter of debate. Inability to detect these positional changes can lead to pedicle perforation while inserting screws using navigation. No study has evaluated the role of O-arm navigation in this patient population. The study population was divided into 2 groups with 19 patients each, one comprising patients who underwent O-arm navigation-based pedicle screw insertion (group 1) and the other comprising patients who underwent free-hand pedicle screw insertion technique (group 2). A total of 152 pedicle screws were implanted in 38 patients for 1-level instrumented fusion for degenerative lumbar spondylolisthesis. Intraoperative 3-dimensional computed tomography scans using the O-arm were obtained for all patients after insertion of pedicle screws. The images were reviewed intraoperatively and postoperatively for the analysis of pedicle breaches. Assessments in either of the group included (i) accuracy of placement of screws; (ii) the rate and direction of perforation; and (iii) the number of segments the perforated screw was away from the navigation tracker. Mean age of patients in group 1 (O-arm navigation-assisted) was 60 years (SD 11.25; range, 37-73 y), whereas in group 2 (free-hand pedicle screw) was 62 years (SD 18.07; range, 36-90 y). Overall anatomic perforation rate was 12.5% (19/152). Individually, group 1 had 14.47% (11/76) of perforations in comparison with 10.53% (8/76) observed in group 2. The difference was not statistically significant. The lateral margin was the most common site of perforation in both group 1 (64%, 7/11) and group 2 (62.5%, 5/8). Functional perforation rate for the series was 3.3% (5/152), with group 1 having 2.63% (2/76) and group 2 having 3.95% (3/76). The rate of perforation (PR) was significantly higher statistically when the tracker was placed 3 or more [PR 37.5% (6/16)] spinal segments away from instrumented segment compared with when it was placed 1 (0%) or 2 [PR 13.89% (5/36)] spinal segments away. Overall, 11 screws (11/152, 7.24%) had grade 2 perforations and had to be revised. No neurological complications were observed in the series. O-arm navigation does not provide any significant advantage over conventional free-hand pedicle screw insertion technique in patients with single-level degenerative spondylolisthesis. The accuracy is dependent on the distance of the tracker from the level of instrumentation. Lateral perforations are more common because of instability at the instrumented level leading to translation and rotation of the vertebral body while placing pedicle screws leading to preferential lateral trajectory. These lateral perforations could not be prevented by using navigation. However, no significant complications were noted in either technique.

Clarissa Spoken Dialogue System for Procedure Reading and Navigation

NASA Technical Reports Server (NTRS)

Hieronymus, James; Dowding, John

2004-01-01

Speech is the most natural modality for humans use to communicate with other people, agents and complex systems. A spoken dialogue system must be robust to noise and able to mimic human conversational behavior, like correcting misunderstandings, answering simple questions about the task and understanding most well formed inquiries or commands. The system aims to understand the meaning of the human utterance, and if it does not, then it discards the utterance as being meant for someone else. The first operational system is Clarissa, a conversational procedure reader and navigator, which will be used in a System Development Test Objective (SDTO) on the International Space Station (ISS) during Expedition 10. In the present environment one astronaut reads the procedure on a Manual Procedure Viewer (MPV) or paper, and has to stop to read or turn pages, shifting focus from the task. Clarissa is designed to read and navigate ISS procedures entirely with speech, while the astronaut has his eyes and hands engaged in performing the task. The system also provides an MPV like graphical interface so the procedure can be read visually. A demo of the system will be given.

Navigation of the autonomous vehicle reverse movement

NASA Astrophysics Data System (ADS)

Rachkov, M.; Petukhov, S.

2018-02-01

The paper presents a mathematical formulation of the vehicle reverse motion along a multi-link polygonal trajectory consisting of rectilinear segments interconnected by nodal points. Relevance of the problem is caused by the need to solve a number of tasks: to save the vehicle in the event of а communication break by returning along the trajectory already passed, to avoid a turn on the ground in constrained obstacles or dangerous conditions, or a partial return stroke for the subsequent bypass of the obstacle and continuation of the forward movement. The method of navigation with direct movement assumes that the reverse path is elaborated by using landmarks. To measure landmarks on board, a block of cameras is placed on a vehicle controlled by the operator through the radio channel. Errors in estimating deviation from the nominal trajectory of motion are determined using the multidimensional correlation analysis apparatus based on the dynamics of a lateral deviation error and a vehicle speed error. The result of the experiment showed a relatively high accuracy in determining the state vector that provides the vehicle reverse motion relative to the reference trajectory with a practically acceptable error while returning to the start point.

Natural locomotion based on a reduced set of inertial sensors: Decoupling body and head directions indoors

PubMed Central

Diaz-Estrella, Antonio; Reyes-Lecuona, Arcadio; Langley, Alyson; Brown, Michael; Sharples, Sarah

2018-01-01

Inertial sensors offer the potential for integration into wireless virtual reality systems that allow the users to walk freely through virtual environments. However, owing to drift errors, inertial sensors cannot accurately estimate head and body orientations in the long run, and when walking indoors, this error cannot be corrected by magnetometers, due to the magnetic field distortion created by ferromagnetic materials present in buildings. This paper proposes a technique, called EHBD (Equalization of Head and Body Directions), to address this problem using two head- and shoulder-located magnetometers. Due to their proximity, their distortions are assumed to be similar and the magnetometer measurements are used to detect when the user is looking straight forward. Then, the system corrects the discrepancies between the estimated directions of the head and the shoulder, which are provided by gyroscopes and consequently are affected by drift errors. An experiment is conducted to evaluate the performance of this technique in two tasks (navigation and navigation plus exploration) and using two different locomotion techniques: (1) gaze-directed mode (GD) in which the walking direction is forced to be the same as the head direction, and (2) decoupled direction mode (DD) in which the walking direction can be different from the viewing direction. The obtained results show that both locomotion modes show similar matching of the target path during the navigation task, while DD’s path matches the target path more closely than GD in the navigation plus exploration task. These results validate the EHBD technique especially when allowing different walking and viewing directions in the navigation plus exploration tasks, as expected. While the proposed method does not reach the accuracy of optical tracking (ideal case), it is an acceptable and satisfactory solution for users and is much more compact, portable and economical. PMID:29621298

Choice-specific sequences in parietal cortex during a virtual-navigation decision task

PubMed Central

Harvey, Christopher D.; Coen, Philip; Tank, David W.

2012-01-01

The posterior parietal cortex (PPC) plays an important role in many cognitive behaviors; however, the neural circuit dynamics underlying PPC function are not well understood. Here we optically imaged the spatial and temporal activity patterns of neuronal populations in mice performing a PPC-dependent task that combined a perceptual decision and memory-guided navigation in a virtual environment. Individual neurons had transient activation staggered relative to one another in time, forming a sequence of neuronal activation spanning the entire length of a task trial. Distinct sequences of neurons were triggered on trials with opposite behavioral choices and defined divergent, choice-specific trajectories through a state space of neuronal population activity. Cells participating in the different sequences and at distinct time points in the task were anatomically intermixed over microcircuit length scales (< 100 micrometers). During working memory decision tasks the PPC may therefore perform computations through sequence-based circuit dynamics, rather than long-lived stable states, implemented using anatomically intermingled microcircuits. PMID:22419153

Augmented Reality for the Assessment of Children's Spatial Memory in Real Settings

PubMed Central

Juan, M.-Carmen; Mendez-Lopez, Magdalena; Perez-Hernandez, Elena; Albiol-Perez, Sergio

2014-01-01

Short-term memory can be defined as the capacity for holding a small amount of information in mind in an active state for a short period of time. Although some instruments have been developed to study spatial short-term memory in real environments, there are no instruments that are specifically designed to assess visuospatial short-term memory in an attractive way to children. In this paper, we present the ARSM (Augmented Reality Spatial Memory) task, the first Augmented Reality task that involves a user's movement to assess spatial short-term memory in healthy children. The experimental procedure of the ARSM task was designed to assess the children's skill to retain visuospatial information. They were individually asked to remember the real place where augmented reality objects were located. The children (N = 76) were divided into two groups: preschool (5–6 year olds) and primary school (7–8 year olds). We found a significant improvement in ARSM task performance in the older group. The correlations between scores for the ARSM task and traditional procedures were significant. These traditional procedures were the Dot Matrix subtest for the assessment of visuospatial short-term memory of the computerized AWMA-2 battery and a parent's questionnaire about a child's everyday spatial memory. Hence, we suggest that the ARSM task has high verisimilitude with spatial short-term memory skills in real life. In addition, we evaluated the ARSM task's usability and perceived satisfaction. The study revealed that the younger children were more satisfied with the ARSM task. This novel instrument could be useful in detecting visuospatial short-term difficulties that affect specific developmental navigational disorders and/or school academic achievement. PMID:25438146

Augmented reality for the assessment of children's spatial memory in real settings.

PubMed

Juan, M-Carmen; Mendez-Lopez, Magdalena; Perez-Hernandez, Elena; Albiol-Perez, Sergio

2014-01-01

Short-term memory can be defined as the capacity for holding a small amount of information in mind in an active state for a short period of time. Although some instruments have been developed to study spatial short-term memory in real environments, there are no instruments that are specifically designed to assess visuospatial short-term memory in an attractive way to children. In this paper, we present the ARSM (Augmented Reality Spatial Memory) task, the first Augmented Reality task that involves a user's movement to assess spatial short-term memory in healthy children. The experimental procedure of the ARSM task was designed to assess the children's skill to retain visuospatial information. They were individually asked to remember the real place where augmented reality objects were located. The children (N = 76) were divided into two groups: preschool (5-6 year olds) and primary school (7-8 year olds). We found a significant improvement in ARSM task performance in the older group. The correlations between scores for the ARSM task and traditional procedures were significant. These traditional procedures were the Dot Matrix subtest for the assessment of visuospatial short-term memory of the computerized AWMA-2 battery and a parent's questionnaire about a child's everyday spatial memory. Hence, we suggest that the ARSM task has high verisimilitude with spatial short-term memory skills in real life. In addition, we evaluated the ARSM task's usability and perceived satisfaction. The study revealed that the younger children were more satisfied with the ARSM task. This novel instrument could be useful in detecting visuospatial short-term difficulties that affect specific developmental navigational disorders and/or school academic achievement.

Behavioral correlates of the distributed coding of spatial context.

PubMed

Anderson, Michael I; Killing, Sarah; Morris, Caitlin; O'Donoghue, Alan; Onyiagha, Dikennam; Stevenson, Rosemary; Verriotis, Madeleine; Jeffery, Kathryn J

2006-01-01

Hippocampal place cells respond heterogeneously to elemental changes of a compound spatial context, suggesting that they form a distributed code of context, whereby context information is shared across a population of neurons. The question arises as to what this distributed code might be useful for. The present study explored two possibilities: one, that it allows contexts with common elements to be disambiguated, and the other, that it allows a given context to be associated with more than one outcome. We used two naturalistic measures of context processing in rats, rearing and thigmotaxis (boundary-hugging), to explore how rats responded to contextual novelty and to relate this to the behavior of place cells. In experiment 1, rats showed dishabituation of rearing to a novel reconfiguration of familiar context elements, suggesting that they perceived the reconfiguration as novel, a behavior that parallels that of place cells in a similar situation. In experiment 2, rats were trained in a place preference task on an open-field arena. A change in the arena context triggered renewed thigmotaxis, and yet navigation continued unimpaired, indicating simultaneous representation of both the altered contextual and constant spatial cues. Place cells similarly exhibited a dual population of responses, consistent with the hypothesis that their activity underlies spatial behavior. Together, these experiments suggest that heterogeneous context encoding (or "partial remapping") by place cells may function to allow the flexible assignment of associations to contexts, a faculty that could be useful in episodic memory encoding. Copyright (c) 2006 Wiley-Liss, Inc.

Evaluation of a novel flexible snake robot for endoluminal surgery.

PubMed

Patel, Nisha; Seneci, Carlo A; Shang, Jianzhong; Leibrandt, Konrad; Yang, Guang-Zhong; Darzi, Ara; Teare, Julian

2015-11-01

Endoluminal therapeutic procedures such as endoscopic submucosal dissection are increasingly attractive given the shift in surgical paradigm towards minimally invasive surgery. This novel three-channel articulated robot was developed to overcome the limitations of the flexible endoscope which poses a number of challenges to endoluminal surgery. The device enables enhanced movement in a restricted workspace, with improved range of motion and with the accuracy required for endoluminal surgery. To evaluate a novel flexible robot for therapeutic endoluminal surgery. Bench-top studies. Research laboratory. Targeting and navigation tasks of the robot were performed to explore the range of motion and retroflexion capabilities. Complex endoluminal tasks such as endoscopic mucosal resection were also simulated. Successful completion, accuracy and time to perform the bench-top tasks were the main outcome measures. The robot ranges of movement, retroflexion and navigation capabilities were demonstrated. The device showed significantly greater accuracy of targeting in a retroflexed position compared to a conventional endoscope. Bench-top study and small study sample. We were able to demonstrate a number of simulated endoscopy tasks such as navigation, targeting, snaring and retroflexion. The improved accuracy of targeting whilst in a difficult configuration is extremely promising and may facilitate endoluminal surgery which has been notoriously challenging with a conventional endoscope.

Hippocampal activation and memory performance in schizophrenia depend on strategy use in a virtual maze.

PubMed

Wilkins, Leanne K; Girard, Todd A; Herdman, Katherine A; Christensen, Bruce K; King, Jelena; Kiang, Michael; Bohbot, Veronique D

2017-10-30

Different strategies may be spontaneously adopted to solve most navigation tasks. These strategies are associated with dissociable brain systems. Here, we use brain-imaging and cognitive tasks to test the hypothesis that individuals living with Schizophrenia Spectrum Disorders (SSD) have selective impairment using a hippocampal-dependent spatial navigation strategy. Brain activation and memory performance were examined using functional magnetic resonance imaging (fMRI) during the 4-on-8 virtual maze (4/8VM) task, a human analog of the rodent radial-arm maze that is amenable to both response-based (egocentric or landmark-based) and spatial (allocentric, cognitive mapping) strategies to remember and navigate to target objects. SSD (schizophrenia and schizoaffective disorder) participants who adopted a spatial strategy performed more poorly on the 4/8VM task and had less hippocampal activation than healthy comparison participants using either strategy as well as SSD participants using a response strategy. This study highlights the importance of strategy use in relation to spatial cognitive functioning in SSD. Consistent with a selective-hippocampal dependent deficit in SSD, these results support the further development of protocols to train impaired hippocampal-dependent abilities or harness non-hippocampal dependent intact abilities. Copyright © 2017 Elsevier B.V. All rights reserved.

The impact of goal-oriented task design on neurofeedback learning for brain-computer interface control.

PubMed

McWhinney, S R; Tremblay, A; Boe, S G; Bardouille, T

2018-02-01

Neurofeedback training teaches individuals to modulate brain activity by providing real-time feedback and can be used for brain-computer interface control. The present study aimed to optimize training by maximizing engagement through goal-oriented task design. Participants were shown either a visual display or a robot, where each was manipulated using motor imagery (MI)-related electroencephalography signals. Those with the robot were instructed to quickly navigate grid spaces, as the potential for goal-oriented design to strengthen learning was central to our investigation. Both groups were hypothesized to show increased magnitude of these signals across 10 sessions, with the greatest gains being seen in those navigating the robot due to increased engagement. Participants demonstrated the predicted increase in magnitude, with no differentiation between hemispheres. Participants navigating the robot showed stronger left-hand MI increases than those with the computer display. This is likely due to success being reliant on maintaining strong MI-related signals. While older participants showed stronger signals in early sessions, this trend later reversed, suggesting greater natural proficiency but reduced flexibility. These results demonstrate capacity for modulating neurofeedback using MI over a series of training sessions, using tasks of varied design. Importantly, the more goal-oriented robot control task resulted in greater improvements.

Navigation by environmental geometry: the use of zebrafish as a model

PubMed Central

Lee, Sang Ah; Vallortigara, Giorgio; Flore, Michele; Spelke, Elizabeth S.; Sovrano, Valeria A.

2013-01-01

SUMMARY Sensitivity to environmental shape in spatial navigation has been found, at both behavioural and neural levels, in virtually every species tested, starting early in development. Moreover, evidence that genetic deletions can cause selective deficits in such navigation behaviours suggests a genetic basis to navigation by environmental geometry. Nevertheless, the geometric computations underlying navigation have not been specified in any species. The present study teases apart the geometric components within the traditionally used rectangular enclosure and finds that zebrafish selectively represent distance and directional relationships between extended boundary surfaces. Similar behavioural results in geometric navigation tasks with human children provide prima facie evidence for similar underlying cognitive computations and open new doors for probing the genetic foundations that give rise to these computations. PMID:23788708

Quantum imaging for underwater arctic navigation

NASA Astrophysics Data System (ADS)

Lanzagorta, Marco

2017-05-01

The precise navigation of underwater vehicles is a difficult task due to the challenges imposed by the variable oceanic environment. It is particularly difficult if the underwater vehicle is trying to navigate under the Arctic ice shelf. Indeed, in this scenario traditional navigation devices such as GPS, compasses and gyrocompasses are unavailable or unreliable. In addition, the shape and thickness of the ice shelf is variable throughout the year. Current Arctic underwater navigation systems include sonar arrays to detect the proximity to the ice. However, these systems are undesirable in a wartime environment, as the sound gives away the position of the underwater vehicle. In this paper we briefly describe the theoretical design of a quantum imaging system that could allow the safe and stealthy navigation of underwater Arctic vehicles.

33 CFR 211.19 - Place of filing claims.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Section 211.19 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE REAL ESTATE ACTIVITIES OF THE CORPS OF ENGINEERS IN CONNECTION WITH CIVIL WORKS PROJECTS Real... States Division Engineer in whose jurisdiction the claim arises. ...

Spatial Navigation Impairments Among Intellectually High-Functioning Adults With Autism Spectrum Disorder: Exploring Relations With Theory of Mind, Episodic Memory, and Episodic Future Thinking

PubMed Central

2013-01-01

Research suggests that spatial navigation relies on the same neural network as episodic memory, episodic future thinking, and theory of mind (ToM). Such findings have stimulated theories (e.g., the scene construction and self-projection hypotheses) concerning possible common underlying cognitive capacities. Consistent with such theories, autism spectrum disorder (ASD) is characterized by concurrent impairments in episodic memory, episodic future thinking, and ToM. However, it is currently unclear whether spatial navigation is also impaired. Hence, ASD provides a test case for the scene construction and self-projection theories. The study of spatial navigation in ASD also provides a test of the extreme male brain theory of ASD, which predicts intact or superior navigation (purportedly a systemizing skill) performance among individuals with ASD. Thus, the aim of the current study was to establish whether spatial navigation in ASD is impaired, intact, or superior. Twenty-seven intellectually high-functioning adults with ASD and 28 sex-, age-, and IQ-matched neurotypical comparison adults completed the memory island virtual navigation task. Tests of episodic memory, episodic future thinking, and ToM were also completed. Participants with ASD showed significantly diminished performance on the memory island task, and performance was positively related to ToM and episodic memory, but not episodic future thinking. These results suggest that (contra the extreme male brain theory) individuals with ASD have impaired survey-based navigation skills—that is, difficulties generating cognitive maps of the environment—and adds weight to the idea that scene construction/self-projection are impaired in ASD. The theoretical and clinical implications of these results are discussed. PMID:24364620

76 FR 64859 - Pilot Loading of Navigation and Terrain Awareness Database Updates

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-19

... category the task of updating databases used in self-contained, front-panel or pedestal-mounted navigation... Rule This rulemaking would allow pilots of all certificated aircraft equipped with self-contained... verification, or by errors in ATC assignments which may occur during redirection of the flight. Both types of...

Driving performance changes of middle-aged experienced taxi drivers due to distraction tasks during unexpected situations.

PubMed

Kim, Hyung-Sik; Choi, Mi-Hyun; Choi, Jin-Seung; Kim, Hyun-Joo; Hong, Sang-Pyo; Jun, Jae-Hoon; Tack, Gye-Rae; Kim, Boseong; Min, Ung-Chan; Lim, Dae-Woon; Chung, Soon-Cheol

2013-10-01

This study investigated the effects of distraction taskssuch as sending a text message with a cellphone and searching navigation with car navigation system-on the driving performance of 29 highly experienced taxi drivers in their 50s. All participants were instructed to drive using a driving simulator for 2 min. while maintaining a constant distance from the vehicle in front and a constant speed. Participants drove without any distractions for the first minute. For an additional minute, they performed Driving Only or performed a task while driving (Driving + Sending Text Message or Driving + Searching Navigation). An unexpected situation, in which the participant had to stop abruptly due to a sudden stop of the preceding vehicle, occurred during this period. Driving performance during the unexpected situation was evaluated by car control variables, medial-lateral coefficient of variation and brake time, and by motion variables such as the jerk-cost function. Compared to Driving Only, jerk-cost function, medial-lateral coefficient of variation, and brake time increased during Driving + Sending Text Message or Driving + Searching Navigation.

Supporting the future nuclear workforce with computer-based procedures

DOE PAGES

Oxstrand, Johanna; Le Blanc, Katya

2016-05-01

Here we see that computer-based tools have dramatically increased ease and efficiency of everyday tasks. Gone are the days of paging through a paper catalog, transcribing product numbers, and calculating totals. Today, a consumer can find a product online with a simple search engine, and then purchase it in a matter of a few clicks. Paper catalogs have their place, but it is hard to imagine life without on-line shopping sites. All tasks conducted in a nuclear power plant are guided by procedures, which helps ensure safe and reliable operation of the plants. One prominent goal of the nuclear industrymore » is to minimize the risk of human errors. To achieve this goal one has to ensure tasks are correctly and consistently executed. This is partly achieved by training and by a structured approach to task execution, which is provided by procedures and work instructions. Procedures are used in the nuclear industry to direct workers' actions in a proper sequence. The governing idea is to minimize the reliance on memory and choices made in the field. However, the procedure document may not contain sufficient information to successfully complete the task. Therefore, the worker might have to carry additional documents such as turnover sheets, operation experience, drawings, and other procedures to the work site. The nuclear industry is operated with paper procedures like paper catalogs of the past. A field worker may carry a large stack of documents needed to complete a task to the field. Even though the paper process has helped keep the industry safe for decades, there are limitations to using paper. Paper procedures are static (i.e., the content does not change after the document is printed), difficult to search, and rely heavily on the field worker’s situational awareness and ability to consistently meet the high expectation of human performance excellence. With computer-based procedures (CBPs) that stack of papers may be reduced to the size of a small tablet or even a smart phone. Instead of manually matching equipment identification numbers listed in the procedure with the number on the physical equipment the field worker can simply scan a barcode to ensure the correct valve is opened while simultaneously creating a record. Instead of navigating through a maze of cross-references, CBPs enable intelligent work path navigation which accounts for past decisions and observation, thereby enabling more efficient and safe task completion.« less

Supporting the future nuclear workforce with computer-based procedures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oxstrand, Johanna; Le Blanc, Katya

Here we see that computer-based tools have dramatically increased ease and efficiency of everyday tasks. Gone are the days of paging through a paper catalog, transcribing product numbers, and calculating totals. Today, a consumer can find a product online with a simple search engine, and then purchase it in a matter of a few clicks. Paper catalogs have their place, but it is hard to imagine life without on-line shopping sites. All tasks conducted in a nuclear power plant are guided by procedures, which helps ensure safe and reliable operation of the plants. One prominent goal of the nuclear industrymore » is to minimize the risk of human errors. To achieve this goal one has to ensure tasks are correctly and consistently executed. This is partly achieved by training and by a structured approach to task execution, which is provided by procedures and work instructions. Procedures are used in the nuclear industry to direct workers' actions in a proper sequence. The governing idea is to minimize the reliance on memory and choices made in the field. However, the procedure document may not contain sufficient information to successfully complete the task. Therefore, the worker might have to carry additional documents such as turnover sheets, operation experience, drawings, and other procedures to the work site. The nuclear industry is operated with paper procedures like paper catalogs of the past. A field worker may carry a large stack of documents needed to complete a task to the field. Even though the paper process has helped keep the industry safe for decades, there are limitations to using paper. Paper procedures are static (i.e., the content does not change after the document is printed), difficult to search, and rely heavily on the field worker’s situational awareness and ability to consistently meet the high expectation of human performance excellence. With computer-based procedures (CBPs) that stack of papers may be reduced to the size of a small tablet or even a smart phone. Instead of manually matching equipment identification numbers listed in the procedure with the number on the physical equipment the field worker can simply scan a barcode to ensure the correct valve is opened while simultaneously creating a record. Instead of navigating through a maze of cross-references, CBPs enable intelligent work path navigation which accounts for past decisions and observation, thereby enabling more efficient and safe task completion.« less

Software for Secondary-School Learning About Robotics

NASA Technical Reports Server (NTRS)

Shelton, Robert O.; Smith, Stephanie L.; Truong, Dat; Hodgson, Terry R.

2005-01-01

The ROVer Ranch is an interactive computer program designed to help secondary-school students learn about space-program robotics and related basic scientific concepts by involving the students in simplified design and programming tasks that exercise skills in mathematics and science. The tasks involve building simulated robots and then observing how they behave. The program furnishes (1) programming tools that a student can use to assemble and program a simulated robot and (2) a virtual three-dimensional mission simulator for testing the robot. First, the ROVer Ranch presents fundamental information about robotics, mission goals, and facts about the mission environment. On the basis of this information, and using the aforementioned tools, the student assembles a robot by selecting parts from such subsystems as propulsion, navigation, and scientific tools, the student builds a simulated robot to accomplish its mission. Once the robot is built, it is programmed and then placed in a three-dimensional simulated environment. Success or failure in the simulation depends on the planning and design of the robot. Data and results of the mission are available in a summary log once the mission is concluded.

Wheelchair control by elderly participants in a virtual environment with a brain-computer interface (BCI) and tactile stimulation.

PubMed

Herweg, Andreas; Gutzeit, Julian; Kleih, Sonja; Kübler, Andrea

2016-12-01

Tactile event-related potential (ERP) are rarely used as input signal to control brain-computer-interfaces (BCI) due to their low accuracy and speed (information transfer rate, ITR). Age-related loss of tactile sensibility might further decrease their viability for the target population of BCI. In this study we investigated whether training improves tactile ERP-BCI performance within a virtual wheelchair navigation task. Elderly subjects participated in 5 sessions and tactors were placed at legs, abdomen and back. Mean accuracy and ITR increased from 88.43%/4.5bitsmin -1 in the 1st to 92.56%/4.98bitsmin -1 in the last session. The mean P300 amplitude increased from 5.46μV to 9.22μV. In an optional task participants achieved an accuracy of 95,56% and a mean ITR of 20,73bitsmin -1 which is the highest ever achieved with tactile stimulation. Our sample of elderly people further contributed to the external validity of our results. Copyright © 2016 Elsevier B.V. All rights reserved.

33 CFR 156.210 - General.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL AND HAZARDOUS MATERIAL TRANSFER OPERATIONS Special Requirements for Lightering of Oil and Hazardous Material Cargoes § 156.210 General. (a) No vessel may transfer oil or hazardous materials in a port or place...

33 CFR 156.210 - General.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL AND HAZARDOUS MATERIAL TRANSFER OPERATIONS Special Requirements for Lightering of Oil and Hazardous Material Cargoes § 156.210 General. (a) No vessel may transfer oil or hazardous materials in a port or place...

33 CFR 156.210 - General.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL AND HAZARDOUS MATERIAL TRANSFER OPERATIONS Special Requirements for Lightering of Oil and Hazardous Material Cargoes § 156.210 General. (a) No vessel may transfer oil or hazardous materials in a port or place...

33 CFR 156.210 - General.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL AND HAZARDOUS MATERIAL TRANSFER OPERATIONS Special Requirements for Lightering of Oil and Hazardous Material Cargoes § 156.210 General. (a) No vessel may transfer oil or hazardous materials in a port or place...

33 CFR 156.210 - General.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL AND HAZARDOUS MATERIAL TRANSFER OPERATIONS Special Requirements for Lightering of Oil and Hazardous Material Cargoes § 156.210 General. (a) No vessel may transfer oil or hazardous materials in a port or place...

Functional imaging of hippocampal place cells at cellular resolution during virtual navigation

PubMed Central

Dombeck, Daniel A.; Harvey, Christopher D.; Tian, Lin; Looger, Loren L.; Tank, David W.

2010-01-01

Spatial navigation is a widely employed behavior in rodent studies of neuronal circuits underlying cognition, learning and memory. In vivo microscopy combined with genetically-encoded indicators provides important new tools to study neuronal circuits, but has been technically difficult to apply during navigation. We describe methods to image the activity of hippocampal CA1 neurons with sub-cellular resolution in behaving mice. Neurons expressing the genetically encoded calcium indicator GCaMP3 were imaged through a chronic hippocampal window. Head-fixed mice performed spatial behaviors within a setup combining a virtual reality system and a custom built two-photon microscope. Populations of place cells were optically identified, and the correlation between the location of their place fields in the virtual environment and their anatomical location in the local circuit was measured. The combination of virtual reality and high-resolution functional imaging should allow for a new generation of studies to probe neuronal circuit dynamics during behavior. PMID:20890294

Expected Navigation Flight Performance for the Magnetospheric Multiscale (MMS) Mission

NASA Technical Reports Server (NTRS)

Olson, Corwin; Wright, Cinnamon; Long, Anne

2012-01-01

The Magnetospheric Multiscale (MMS) mission consists of four formation-flying spacecraft placed in highly eccentric elliptical orbits about the Earth. The primary scientific mission objective is to study magnetic reconnection within the Earth s magnetosphere. The baseline navigation concept is the independent estimation of each spacecraft state using GPS pseudorange measurements (referenced to an onboard Ultra Stable Oscillator) and accelerometer measurements during maneuvers. State estimation for the MMS spacecraft is performed onboard each vehicle using the Goddard Enhanced Onboard Navigation System, which is embedded in the Navigator GPS receiver. This paper describes the latest efforts to characterize expected navigation flight performance using upgraded simulation models derived from recent analyses.

Concurrent 3-D sonifications enable the head-up monitoring of two interrelated aircraft navigation instruments.

PubMed

Towers, John; Burgess-Limerick, Robin; Riek, Stephan

2014-12-01

The aim of this study was to enable the head-up monitoring of two interrelated aircraft navigation instruments by developing a 3-D auditory display that encodes this navigation information within two spatially discrete sonifications. Head-up monitoring of aircraft navigation information utilizing 3-D audio displays, particularly involving concurrently presented sonifications, requires additional research. A flight simulator's head-down waypoint bearing and course deviation instrument readouts were conveyed to participants via a 3-D auditory display. Both readouts were separately represented by a colocated pair of continuous sounds, one fixed and the other varying in pitch, which together encoded the instrument value's deviation from the norm. Each sound pair's position in the listening space indicated the left/right parameter of its instrument's readout. Participants' accuracy in navigating a predetermined flight plan was evaluated while performing a head-up task involving the detection of visual flares in the out-of-cockpit scene. The auditory display significantly improved aircraft heading and course deviation accuracy, head-up time, and flare detections. Head tracking did not improve performance by providing participants with the ability to orient potentially conflicting sounds, suggesting that the use of integrated localizing cues was successful. Conclusion: A supplementary 3-D auditory display enabled effective head-up monitoring of interrelated navigation information normally attended to through a head-down display. Pilots operating aircraft, such as helicopters and unmanned aerial vehicles, may benefit from a supplementary auditory display because they navigate in two dimensions while performing head-up, out-of-aircraft, visual tasks.

Using multiple IMUs in a stacked filter configuration for calibration and fine alignment

NASA Astrophysics Data System (ADS)

El-Osery, Aly; Bruder, Stephen; Wedeward, Kevin

2018-05-01

Determination of a vehicle or person's position and/or orientation is a critical task for a multitude of applications ranging from automated cars and first responders to missiles and fighter jets. Most of these applications rely primarily on global navigation satellite systems, e.g., GPS, which are highly vulnerable to degradation whether by environmental factors or malicious actions. The use of inertial navigation techniques has been shown to provide increased reliability of navigation systems in these situations. Due to advances in MEMS technology and processing capabilities, the use of small and low-cost inertial measurement units (IMUs) are becoming increasingly feasible, which results in small size, weight and power (SWaP) solutions. A known limitation of MEMS IMUs are errors that causes the navigation solution to drift; furthermore, calibration and initialization are challenging tasks. In this paper, we investigate the use of multiple IMUs to aid in calibrating the navigation system and obtaining accurate initialization by performing fine alignment. By using a centralized filter, physical constraints between the multiple IMUs on a rigid body are leveraged to provide relative updates, which in turn aids in the estimation of the individual biases and scale-factors. Developed algorithms will be validated through simulation and actual measurements using low-cost IMUs.

Flight assessment of a data-link-based navigation-guidance concept

NASA Technical Reports Server (NTRS)

Abbott, T. S.

1983-01-01

With the proposed introduction of a data-link provision into the Air-Traffic-control (ATC) system, the capability will exist to supplement the ground-air, voice (radio) link with digital, data-link information. Additionally, ATC computers could provide, via the data link guidance and navigation information to the pilot which could then be presented in much the same manner as conventional navigation information. The primary objective of this study was to assess the feasibility and acceptability of using 4-sec and 12-sec information updating to drive conventional cockpit-navigation-instrument formats for path-tracking guidance. A flight test, consisting of 19 tracking tasks, was conducted and, through the use of pilot questionnaires and performance data, the following results were obtained. From a performance standpoint, the 4-sec and 12-sec updating led to a slight degradation in path-tracking performance, relative to continuous updating. From the pilot's viewpoint, the 12-sec data interval was suitable for long path segments (greater than 2 min of flight time), but it was difficult to use on shorter segments because of higher work load and insufficient stabilization time. Overall, it was determined that the utilization of noncontinuous data for navigation was both feasible and acceptable for the prescribed task.

User-Centered Iterative Design of a Collaborative Virtual Environment

DTIC Science & Technology

2001-03-01

cognitive task analysis methods to study land navigators. This study was intended to validate the use of user-centered design methodologies for the design of...have explored the cognitive aspects of collaborative human way finding and design for collaborative virtual environments. Further investigation of design paradigms should include cognitive task analysis and behavioral task analysis.

Solar-based navigation for robotic explorers

NASA Astrophysics Data System (ADS)

Shillcutt, Kimberly Jo

2000-12-01

This thesis introduces the application of solar position and shadowing information to robotic exploration. Power is a critical resource for robots with remote, long-term missions, so this research focuses on the power generation capabilities of robotic explorers during navigational tasks, in addition to power consumption. Solar power is primarily considered, with the possibility of wind power also contemplated. Information about the environment, including the solar ephemeris, terrain features, time of day, and surface location, is incorporated into a planning structure, allowing robots to accurately predict shadowing and thus potential costs and gains during navigational tasks. By evaluating its potential to generate and expend power, a robot can extend its lifetime and accomplishments. The primary tasks studied are coverage patterns, with a variety of plans developed for this research. The use of sun, terrain and temporal information also enables new capabilities of identifying and following sun-synchronous and sun-seeking paths. Digital elevation maps are combined with an ephemeris algorithm to calculate the altitude and azimuth of the sun from surface locations, and to identify and map shadows. Solar navigation path simulators use this information to perform searches through two-dimensional space, while considering temporal changes. Step by step simulations of coverage patterns also incorporate time in addition to location. Evaluations of solar and wind power generation, power consumption, area coverage, area overlap, and time are generated for sets of coverage patterns, with on-board environmental information linked to the simulations. This research is implemented on the Nomad robot for the Robotic Antarctic Meteorite Search. Simulators have been developed for coverage pattern tests, as well as for sun-synchronous and sun-seeking path searches. Results of field work and simulations are reported and analyzed, with demonstrated improvements in efficiency, productivity and lifetime of robotic explorers, along with new solar navigation abilities.

Extended investigation into continuous laser scanning of underground mine workings by means of Landis inertial navigation system

NASA Astrophysics Data System (ADS)

Belyaev, E. N.

2017-10-01

The paper investigates the method of applying mobile scanning systems (MSSs) with inertial navigators in the underground conditions for carrying out the surveying tasks. The available mobile laser scanning systems cannot be used in the underground environment since Global Positioning System (GPS) signals cannot be received in mines. This signal not only is necessary for space positioning, but also operates as the main corrective signal for the primary navigation system - the inertial navigation system. The idea of the method described in this paper consists in using MSSs with a different correction of the inertial system than GPS is.

A simplified satellite navigation system for an autonomous Mars roving vehicle.

NASA Technical Reports Server (NTRS)

Janosko, R. E.; Shen, C. N.

1972-01-01

The use of a retroflecting satellite and a laser rangefinder to navigate a Martian roving vehicle is considered in this paper. It is shown that a simple system can be employed to perform this task. An error analysis is performed on the navigation equations and it is shown that the error inherent in the scheme proposed can be minimized by the proper choice of measurement geometry. A nonlinear programming approach is used to minimize the navigation error subject to constraints that are due to geometric and laser requirements. The problem is solved for a particular set of laser parameters and the optimal solution is presented.

Evaluation of low-cost commercial-off-the-shelf autopilot systems for SUAS operations

NASA Astrophysics Data System (ADS)

Brown, Calvin Thomas

With this increase in unmanned aircraft system (UAS) operations, there is a need for a structured process to evaluate different commercially available systems, particularly autopilots. The Remotely Operated Aircraft Management, Interpretation, and Navigation from Ground or ROAMING scale was developed to meet this need. This scale is a modification of the widely accepted Handling Qualities Rating scale developed by George Cooper and Robert Harper Jr. The Cooper-Harper scale allows pilots to rate a vehicle's performance in completing some task. Similarly, the ROAMING scale allows UAS operators to evaluate the management and observability of UAS in completing some task. The standardized evaluative process consists of cost, size, weight, and power (SWAP) analysis, ease of implementation through procedural description of setup, ROAMING scale rating, a slightly modified NASA TLX rating, and comparison of manual operation to autonomous operation of the task. This standard for evaluation of autopilots and their software will lead to better understanding of the workload placed on UAS operators and indicate where improvements to design and operational procedures can be made. An assortment of low-cost commercial-off-the-shelf (COTS) autopilots were selected for use in the development of the evaluation and results of these tests demonstrate the commonalities and differences in these systems.

Heading-vector navigation based on head-direction cells and path integration.

PubMed

Kubie, John L; Fenton, André A

2009-05-01

Insect navigation is guided by heading vectors that are computed by path integration. Mammalian navigation models, on the other hand, are typically based on map-like place representations provided by hippocampal place cells. Such models compute optimal routes as a continuous series of locations that connect the current location to a goal. We propose a "heading-vector" model in which head-direction cells or their derivatives serve both as key elements in constructing the optimal route and as the straight-line guidance during route execution. The model is based on a memory structure termed the "shortcut matrix," which is constructed during the initial exploration of an environment when a set of shortcut vectors between sequential pairs of visited waypoint locations is stored. A mechanism is proposed for calculating and storing these vectors that relies on a hypothesized cell type termed an "accumulating head-direction cell." Following exploration, shortcut vectors connecting all pairs of waypoint locations are computed by vector arithmetic and stored in the shortcut matrix. On re-entry, when local view or place representations query the shortcut matrix with a current waypoint and goal, a shortcut trajectory is retrieved. Since the trajectory direction is in head-direction compass coordinates, navigation is accomplished by tracking the firing of head-direction cells that are tuned to the heading angle. Section 1 of the manuscript describes the properties of accumulating head-direction cells. It then shows how accumulating head-direction cells can store local vectors and perform vector arithmetic to perform path-integration-based homing. Section 2 describes the construction and use of the shortcut matrix for computing direct paths between any pair of locations that have been registered in the shortcut matrix. In the discussion, we analyze the advantages of heading-based navigation over map-based navigation. Finally, we survey behavioral evidence that nonhippocampal, heading-based navigation is used in small mammals and humans. Copyright 2008 Wiley-Liss, Inc.

Anisotropy of Human Horizontal and Vertical Navigation in Real Space: Behavioral and PET Correlates.

PubMed

Zwergal, Andreas; Schöberl, Florian; Xiong, Guoming; Pradhan, Cauchy; Covic, Aleksandar; Werner, Philipp; Trapp, Christoph; Bartenstein, Peter; la Fougère, Christian; Jahn, Klaus; Dieterich, Marianne; Brandt, Thomas

2016-10-17

Spatial orientation was tested during a horizontal and vertical real navigation task in humans. Video tracking of eye movements was used to analyse the behavioral strategy and combined with simultaneous measurements of brain activation and metabolism ([18F]-FDG-PET). Spatial navigation performance was significantly better during horizontal navigation. Horizontal navigation was predominantly visually and landmark-guided. PET measurements indicated that glucose metabolism increased in the right hippocampus, bilateral retrosplenial cortex, and pontine tegmentum during horizontal navigation. In contrast, vertical navigation was less reliant on visual and landmark information. In PET, vertical navigation activated the bilateral hippocampus and insula. Direct comparison revealed a relative activation in the pontine tegmentum and visual cortical areas during horizontal navigation and in the flocculus, insula, and anterior cingulate cortex during vertical navigation. In conclusion, these data indicate a functional anisotropy of human 3D-navigation in favor of the horizontal plane. There are common brain areas for both forms of navigation (hippocampus) as well as unique areas such as the retrosplenial cortex, visual cortex (horizontal navigation), flocculus, and vestibular multisensory cortex (vertical navigation). Visually guided landmark recognition seems to be more important for horizontal navigation, while distance estimation based on vestibular input might be more relevant for vertical navigation. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

A Leapfrog Navigation System

NASA Astrophysics Data System (ADS)

Opshaug, Guttorm Ringstad

There are times and places where conventional navigation systems, such as the Global Positioning System (GPS), are unavailable due to anything from temporary signal occultations to lack of navigation system infrastructure altogether. The goal of the Leapfrog Navigation System (LNS) is to provide localized positioning services for such cases. The concept behind leapfrog navigation is to advance a group of navigation units teamwise into an area of interest. In a practical 2-D case, leapfrogging assumes known initial positions of at least two currently stationary navigation units. Two or more mobile units can then start to advance into the area of interest. The positions of the mobiles are constantly being calculated based on cross-range distance measurements to the stationary units, as well as cross-ranges among the mobiles themselves. At some point the mobile units stop, and the stationary units are released to move. This second team of units (now mobile) can then overtake the first team (now stationary) and travel even further towards the common goal of the group. Since there always is one stationary team, the position of any unit can be referenced back to the initial positions. Thus, LNS provides absolute positioning. I developed navigation algorithms needed to solve leapfrog positions based on cross-range measurements. I used statistical tools to predict how position errors would grow as a function of navigation unit geometry, cross-range measurement accuracy and previous position errors. Using this knowledge I predicted that a 4-unit Leapfrog Navigation System using 100 m baselines and 200 m leap distances could travel almost 15 km before accumulating absolute position errors of 10 m (1sigma). Finally, I built a prototype leapfrog navigation system using 4 GPS transceiver ranging units. I placed the 4 units in the vertices a 10m x 10m square, and leapfrogged the group 20 meters forwards, and then back again (40 m total travel). Average horizontal RMS position errors never exceeded 16 cm during these field tests.

Task-Based Navigation of a Taxonomy Interface to a Digital Repository

ERIC Educational Resources Information Center

Khoo, Christopher S. G.; Wang, Zhonghong; Chaudhry, Abdus Sattar

2012-01-01

Introduction: This is a study of hierarchical navigation; how users browse a taxonomy-based interface to an organizational repository to locate information resources. The study is part of a project to develop a taxonomy for an library and information science department to organize resources and support user browsing in a digital repository.…

Improving Operational Effectiveness of Tactical Long Endurance Unmanned Aerial Systems (TALEUAS) by Utilizing Solar Power

DTIC Science & Technology

2014-06-01

Speed xiii TEK Total Energy Compensated TSP traveling salesman problem UAV unmanned aerial vehicle UDP user datagram protocol UKF unscented...discretized map, and use the map to optimally solve the navigation task. The optimal navigation solution utilizes the well-known “ travelling salesman problem ...2 C. FORMULATION OF THE PROBLEM .................................................. 3 D

N-methyl-d-aspartate receptors, learning and memory: chronic intraventricular infusion of the NMDA receptor antagonist d-AP5 interacts directly with the neural mechanisms of spatial learning.

PubMed

Morris, R G M; Steele, R J; Bell, J E; Martin, S J

2013-03-01

Three experiments were conducted to contrast the hypothesis that hippocampal N-methyl-d-aspartate (NMDA) receptors participate directly in the mechanisms of hippocampus-dependent learning with an alternative view that apparent impairments of learning induced by NMDA receptor antagonists arise because of drug-induced neuropathological and/or sensorimotor disturbances. In experiment 1, rats given a chronic i.c.v. infusion of d-AP5 (30 mm) at 0.5 μL/h were selectively impaired, relative to aCSF-infused animals, in place but not cued navigation learning when they were trained during the 14-day drug infusion period, but were unimpaired on both tasks if trained 11 days after the minipumps were exhausted. d-AP5 caused sensorimotor disturbances in the spatial task, but these gradually worsened as the animals failed to learn. Histological assessment of potential neuropathological changes revealed no abnormalities in d-AP5-treated rats whether killed during or after chronic drug infusion. In experiment 2, a deficit in spatial learning was also apparent in d-AP5-treated rats trained on a spatial reference memory task involving two identical but visible platforms, a task chosen and shown to minimise sensorimotor disturbances. HPLC was used to identify the presence of d-AP5 in selected brain areas. In Experiment 3, rats treated with d-AP5 showed a delay-dependent deficit in spatial memory in the delayed matching-to-place protocol for the water maze. These data are discussed with respect to the learning mechanism and sensorimotor accounts of the impact of NMDA receptor antagonists on brain function. We argue that NMDA receptor mechanisms participate directly in spatial learning. © 2013 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Transmission of linearly polarized light in seawater: implications for polarization signaling.

PubMed

Shashar, Nadav; Sabbah, Shai; Cronin, Thomas W

2004-09-01

Partially linearly polarized light is abundant in the oceans. The natural light field is partially polarized throughout the photic range, and some objects and animals produce a polarization pattern of their own. Many polarization-sensitive marine animals take advantage of the polarization information, using it for tasks ranging from navigation and finding food to communication. In such tasks, the distance to which the polarization information propagates is of great importance. Using newly designed polarization sensors, we measured the changes in linear polarization underwater as a function of distance from a standard target. In the relatively clear waters surrounding coral reefs, partial (%) polarization decreased exponentially as a function of distance from the target, resulting in a 50% reduction of partial polarization at a distance of 1.25-3 m, depending on water quality. Based on these measurements, we predict that polarization sensitivity will be most useful for short-range (in the order of meters) visual tasks in water and less so for detecting objects, signals, or structures from far away. Navigation and body orientation based on the celestial polarization pattern are predicted to be limited to shallow waters as well, while navigation based on the solar position is possible through a deeper range.

Software Would Largely Automate Design of Kalman Filter

NASA Technical Reports Server (NTRS)

Chuang, Jason C. H.; Negast, William J.

2005-01-01

Embedded Navigation Filter Automatic Designer (ENFAD) is a computer program being developed to automate the most difficult tasks in designing embedded software to implement a Kalman filter in a navigation system. The most difficult tasks are selection of error states of the filter and tuning of filter parameters, which are timeconsuming trial-and-error tasks that require expertise and rarely yield optimum results. An optimum selection of error states and filter parameters depends on navigation-sensor and vehicle characteristics, and on filter processing time. ENFAD would include a simulation module that would incorporate all possible error states with respect to a given set of vehicle and sensor characteristics. The first of two iterative optimization loops would vary the selection of error states until the best filter performance was achieved in Monte Carlo simulations. For a fixed selection of error states, the second loop would vary the filter parameter values until an optimal performance value was obtained. Design constraints would be satisfied in the optimization loops. Users would supply vehicle and sensor test data that would be used to refine digital models in ENFAD. Filter processing time and filter accuracy would be computed by ENFAD.

Dissociation of spatial navigation and visual guidance performance in Purkinje cell degeneration (pcd) mutant mice.

PubMed

Goodlett, C R; Hamre, K M; West, J R

1992-04-10

Spatial learning in rodents requires normal functioning of hippocampal and cortical structures. Recent data suggest that the cerebellum may also be essential. Neurological mutant mice with dysgenesis of the cerebellum provide useful models to examine the effects of abnormal cerebellar function. Mice with one such mutation, Purkinje cell degeneration (pcd), in which Purkinje cells degenerate between the third and fourth postnatal weeks, were evaluated for performance of spatial navigation learning and visual guidance learning in the Morris maze swim-escape task. Unaffected littermates and C57BL/6J mice served as controls. Separate groups of pcd and control mice were tested at 30, 50 and 110 days of age. At all ages, pcd mice had severe deficits in distal-cue (spatial) navigation, failing to decrease path lengths over training and failing to express appropriate spatial biases on probe trials. On the proximal-cue (visual guidance) task, whenever performance differences between groups did occur, they were limited to the initial trials. The ability of the pcd mice to perform the proximal-cue but not the distal-cue task indicates that the massive spatial navigation deficit was not due simply to motor dysfunction. Histological evaluations confirmed that the pcd mutation resulted in Purkinje cell loss without significant depletion of cells in the hippocampal formation. These data provide further evidence that the cerebellum is vital for the expression of behavior directed by spatial cognitive processes.

Ecological Virtual Reality Evaluation of Neglect Symptoms (EVENS): Effects of Virtual Scene Complexity in the Assessment of Poststroke Unilateral Spatial Neglect.

PubMed

Ogourtsova, Tatiana; Archambault, Philippe; Sangani, Samir; Lamontagne, Anouk

2018-01-01

Unilateral spatial neglect (USN) is a highly prevalent and disabling poststroke impairment. USN is traditionally assessed with paper-and-pencil tests that lack ecological validity, generalization to real-life situations and are easily compensated for in chronic stages. Virtual reality (VR) can, however, counteract these limitations. We aimed to examine the feasibility of a novel assessment of USN symptoms in a functional shopping activity, the Ecological VR-based Evaluation of Neglect Symptoms (EVENS). EVENS is immersive and consists of simple and complex 3-dimensional scenes depicting grocery shopping shelves, where joystick-based object detection and navigation tasks are performed while seated. Effects of virtual scene complexity on navigational and detection abilities in patients with (USN+, n = 12) and without (USN-, n = 15) USN following a right hemisphere stroke and in age-matched healthy controls (HC, n = 9) were determined. Longer detection times, larger mediolateral deviations from ideal paths and longer navigation times were found in USN+ versus USN- and HC groups, particularly in the complex scene. EVENS detected lateralized and nonlateralized USN-related deficits, performance alterations that were dependent or independent of USN severity, and performance alterations in 3 USN- subjects versus HC. EVENS' environmental changing complexity, along with the functional tasks of far space detection and navigation can potentially be clinically relevant and warrant further empirical investigation. Findings are discussed in terms of attentional models, lateralized versus nonlateralized deficits in USN, and tasks-specific mechanisms.

There's No Place Like Home

MedlinePlus

... Navigation Bar Home Current Issue Past Issues Feature: Senior Living There's No Place Like Home Past Issues / ... state offices on aging; social services organizations; nearby senior centers; and civic, tribal, and religious organizations. They ...

Instrument-mounted displays for reducing cognitive load during surgical navigation.

PubMed

Herrlich, Marc; Tavakol, Parnian; Black, David; Wenig, Dirk; Rieder, Christian; Malaka, Rainer; Kikinis, Ron

2017-09-01

Surgical navigation systems rely on a monitor placed in the operating room to relay information. Optimal monitor placement can be challenging in crowded rooms, and it is often not possible to place the monitor directly beside the situs. The operator must split attention between the navigation system and the situs. We present an approach for needle-based interventions to provide navigational feedback directly on the instrument and close to the situs by mounting a small display onto the needle. By mounting a small and lightweight smartwatch display directly onto the instrument, we are able to provide navigational guidance close to the situs and directly in the operator's field of view, thereby reducing the need to switch the focus of view between the situs and the navigation system. We devise a specific variant of the established crosshair metaphor suitable for the very limited screen space. We conduct an empirical user study comparing our approach to using a monitor and a combination of both. Results from the empirical user study show significant benefits for cognitive load, user preference, and general usability for the instrument-mounted display, while achieving the same level of performance in terms of time and accuracy compared to using a monitor. We successfully demonstrate the feasibility of our approach and potential benefits. With ongoing technological advancements, instrument-mounted displays might complement standard monitor setups for surgical navigation in order to lower cognitive demands and for improved usability of such systems.

Frame of reference for electronic maps - The relevance of spatial cognition, mental rotation, and componential task analysis

NASA Technical Reports Server (NTRS)

Wickens, Christopher D.; Aretz, Anthony; Harwood, Kelly

1989-01-01

Three experiments are reported that examine the difference between north-up and track-up maps for airborne navigation. The results of the first two experiments, conducted in a basic laboratory setting, identified the cost associated with mental rotation, when a north-up map is used. However, the data suggest that these costs are neither large nor consistent. The third experiment examined a range of tasks in a higher fidelity helicopter flight simulation, and associated the costs of north-up maps with a cognitive component related to orientation, and the costs of track-up maps with a cognitive component related to inconsistent landmark location. Different tasks are associated with different dependence on these components. The results are discussed in terms of their implications for map design, and for cognitive models of navigational processes.

Regionalized Lunar South Pole Surface Navigation System Analysis

NASA Technical Reports Server (NTRS)

Welch, Bryan W.

2008-01-01

Apollo missions utilized Earth-based assets for navigation because the landings took place at lunar locations in constant view from the Earth. The new exploration campaign to the lunar south pole region will have limited Earth visibility, but the extent to which a navigation system comprised solely of Earth-based tracking stations will provide adequate navigation solutions in this region is unknown. This report presents a dilution-of-precision (DoP)-based, stationary surface navigation analysis of the performance of multiple lunar satellite constellations, Earth-based deep space network assets, and combinations thereof. Results show that kinematic and integrated solutions cannot be provided by the Earth-based deep space network stations. Also, the stationary surface navigation system needs to be operated either as a two-way navigation system or as a one-way navigation system with local terrain information, while the position solution is integrated over a short duration of time with navigation signals being provided by a lunar satellite constellation.

Global-local processing relates to spatial and verbal processing: implications for sex differences in cognition.

PubMed

Pletzer, Belinda; Scheuringer, Andrea; Scherndl, Thomas

2017-09-05

Sex differences have been reported for a variety of cognitive tasks and related to the use of different cognitive processing styles in men and women. It was recently argued that these processing styles share some characteristics across tasks, i.e. male approaches are oriented towards holistic stimulus aspects and female approaches are oriented towards stimulus details. In that respect, sex-dependent cognitive processing styles share similarities with attentional global-local processing. A direct relationship between cognitive processing and global-local processing has however not been previously established. In the present study, 49 men and 44 women completed a Navon paradigm and a Kimchi Palmer task as well as a navigation task and a verbal fluency task with the goal to relate the global advantage (GA) effect as a measure of global processing to holistic processing styles in both tasks. Indeed participants with larger GA effects displayed more holistic processing during spatial navigation and phonemic fluency. However, the relationship to cognitive processing styles was modulated by the specific condition of the Navon paradigm, as well as the sex of participants. Thus, different types of global-local processing play different roles for cognitive processing in men and women.

Intelligent navigation and accurate positioning of an assist robot in indoor environments

NASA Astrophysics Data System (ADS)

Hua, Bin; Rama, Endri; Capi, Genci; Jindai, Mitsuru; Tsuri, Yosuke

2017-12-01

Intact robot's navigation and accurate positioning in indoor environments are still challenging tasks. Especially in robot applications, assisting disabled and/or elderly people in museums/art gallery environments. In this paper, we present a human-like navigation method, where the neural networks control the wheelchair robot to reach the goal location safely, by imitating the supervisor's motions, and positioning in the intended location. In a museum similar environment, the mobile robot starts navigation from various positions, and uses a low-cost camera to track the target picture, and a laser range finder to make a safe navigation. Results show that the neural controller with the Conjugate Gradient Backpropagation training algorithm gives a robust response to guide the mobile robot accurately to the goal position.

Ratbot automatic navigation by electrical reward stimulation based on distance measurement in unknown environments.

PubMed

Gao, Liqiang; Sun, Chao; Zhang, Chen; Zheng, Nenggan; Chen, Weidong; Zheng, Xiaoxiang

2013-01-01

Traditional automatic navigation methods for bio-robots are constrained to configured environments and thus can't be applied to tasks in unknown environments. With no consideration of bio-robot's own innate living ability and treating bio-robots in the same way as mechanical robots, those methods neglect the intelligence behavior of animals. This paper proposes a novel ratbot automatic navigation method in unknown environments using only reward stimulation and distance measurement. By utilizing rat's habit of thigmotaxis and its reward-seeking behavior, this method is able to incorporate rat's intrinsic intelligence of obstacle avoidance and path searching into navigation. Experiment results show that this method works robustly and can successfully navigate the ratbot to a target in the unknown environment. This work might put a solid base for application of ratbots and also has significant implication of automatic navigation for other bio-robots as well.

Songlines and navigation in Wardaman and other Australian Aboriginal cultures

NASA Astrophysics Data System (ADS)

Norris, Ray P.; Harney, Bill Yidumdum

2014-07-01

We discuss the songlines and navigation of the Wardaman people, and place them in context by comparing them with corresponding practices in other Aboriginal Australian language groups, using previously-unpublished information and also information drawn from the literature. Songlines are effectively oral maps of the landscape, enabling the transmission of oral navigational skills in cultures that do not have a written language. In many cases, songlines on the Earth are mirrored by songlines in the sky, enabling the sky to be used as a navigational tool, both by using it as a compass and by using it as a mnemonic.

Does ventrolateral prefrontal cortex help in searching for the lost key? Evidence from an fNIRS study.

PubMed

Carrieri, Marika; Lancia, Stefania; Bocchi, Alessia; Ferrari, Marco; Piccardi, Laura; Quaresima, Valentina

2018-06-01

The Key Search Task (KST) is a neuropsychological test that requires strategies for searching a lost key in an imaginary field. This request may involve different cognitive processes as mental imagery and navigation planning. This study was aimed at investigating, by a twenty-channel functional near-infrared spectroscopy (fNIRS) system, the hemodynamic response (i.e., oxygenated-hemoglobin (O 2 Hb) and deoxygenated-hemoglobin (HHb) changes) of the prefrontal cortex in navigation planning. A right ventrolateral prefrontal cortex (rVLPFC) activation during the KST was hypothesized. Thirty-eight volunteers performed the KST and a Control Task (CT), the latter requiring the volunteers to mark the X letter. An activation (i.e., increase/decrease in O 2 Hb/HHb) of: 1) rVLPFC during the KST execution, and 2) bilateral dorsolateral prefrontal cortex (DLPFC) during the CT execution was found. The present study provides a contribution in localizing the rVLPFC as the critically active region, within the frontal lobes, that was found maximally activated during mental navigation in the mind's eye of healthy participants while performing the KST. Considering the contribution of rVLPFC in spatial navigation, its activation suggests that the KST could be adopted in the clinical routine for investigating navigation planning. Compared to other neuroimaging techniques, fNIRS (with its relatively low physical constraints) contributes to better clarifying the role of rVLPFC in some aspects of human navigation. Therefore, the combined use of the fNIRS and the KST could be considered as an innovative and valid tool to evaluate fundamental functions for everyday life, such as spatial navigation planning.

33 CFR 110.83 - Chicago Harbor, Ill.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Section 110.83 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Special Anchorage Areas § 110.83 Chicago Harbor, Ill. (a) Grant Park North-A... and type of any moorings placed in the special anchorage areas in this section. [CGD09-83-02, 50 FR...

33 CFR 110.30 - Boston Harbor, Mass.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Section 110.30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Special Anchorage Areas § 110.30 Boston Harbor, Mass. (a) Vicinity of South Boston... moorings are to be so placed that no moored vessel will extend beyond the limit of the anchorage area. (i...

33 CFR 110.30 - Boston Harbor, Mass.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Section 110.30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Special Anchorage Areas § 110.30 Boston Harbor, Mass. (a) Vicinity of South Boston... moorings are to be so placed that no moored vessel will extend beyond the limit of the anchorage area. (i...

33 CFR 110.30 - Boston Harbor, Mass.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Section 110.30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Special Anchorage Areas § 110.30 Boston Harbor, Mass. (a) Vicinity of South Boston... moorings are to be so placed that no moored vessel will extend beyond the limit of the anchorage area. (i...

33 CFR 154.510 - Loading arms.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Loading arms. 154.510 Section 154... FACILITIES TRANSFERRING OIL OR HAZARDOUS MATERIAL IN BULK Equipment Requirements § 154.510 Loading arms. (a) Each mechanical loading arm used for transferring oil or hazardous material and placed into service...

33 CFR 154.510 - Loading arms.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Loading arms. 154.510 Section 154... FACILITIES TRANSFERRING OIL OR HAZARDOUS MATERIAL IN BULK Equipment Requirements § 154.510 Loading arms. (a) Each mechanical loading arm used for transferring oil or hazardous material and placed into service...

33 CFR 154.510 - Loading arms.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Loading arms. 154.510 Section 154... FACILITIES TRANSFERRING OIL OR HAZARDOUS MATERIAL IN BULK Equipment Requirements § 154.510 Loading arms. (a) Each mechanical loading arm used for transferring oil or hazardous material and placed into service...

33 CFR 84.23 - Maneuvering light.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Maneuvering light. 84.23 Section... RULES ANNEX I: POSITIONING AND TECHNICAL DETAILS OF LIGHTS AND SHAPES § 84.23 Maneuvering light. Notwithstanding the provisions of § 84.03(f), the maneuvering light described in Rule 34(b) shall be placed...

33 CFR 84.23 - Maneuvering light.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Maneuvering light. 84.23 Section... RULES ANNEX I: POSITIONING AND TECHNICAL DETAILS OF LIGHTS AND SHAPES § 84.23 Maneuvering light. Notwithstanding the provisions of § 84.03(f), the maneuvering light described in Rule 34(b) shall be placed...

33 CFR 84.23 - Maneuvering light.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Maneuvering light. 84.23 Section... RULES ANNEX I: POSITIONING AND TECHNICAL DETAILS OF LIGHTS AND SHAPES § 84.23 Maneuvering light. Notwithstanding the provisions of § 84.03(f), the maneuvering light described in Rule 34(b) shall be placed...

33 CFR 84.23 - Maneuvering light.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Maneuvering light. 84.23 Section... RULES ANNEX I: POSITIONING AND TECHNICAL DETAILS OF LIGHTS AND SHAPES § 84.23 Maneuvering light. Notwithstanding the provisions of § 84.03(f), the maneuvering light described in Rule 34(b) shall be placed...

33 CFR 84.23 - Maneuvering light.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Maneuvering light. 84.23 Section... RULES ANNEX I: POSITIONING AND TECHNICAL DETAILS OF LIGHTS AND SHAPES § 84.23 Maneuvering light. Notwithstanding the provisions of § 84.03(f), the maneuvering light described in Rule 34(b) shall be placed...

Air Force construction automation/robotics

NASA Technical Reports Server (NTRS)

Nease, AL; Dusseault, Christopher

1994-01-01

The Air Force has several unique requirements that are being met through the development of construction robotic technology. The missions associated with these requirements place construction/repair equipment operators in potentially harmful situations. Additionally, force reductions require that human resources be leveraged to the maximum extent possible and that more stringent construction repair requirements push for increased automation. To solve these problems, the U.S. Air Force is undertaking a research and development effort at Tyndall AFB, FL to develop robotic teleoperation, telerobotics, robotic vehicle communications, automated damage assessment, vehicle navigation, mission/vehicle task control architecture, and associated computing environment. The ultimate goal is the fielding of robotic repair capability operating at the level of supervised autonomy. The authors of this paper will discuss current and planned efforts in construction/repair, explosive ordnance disposal, hazardous waste cleanup, fire fighting, and space construction.

The "Where" of Doctoral Research: The Role of "Place" in Creating Meaning

ERIC Educational Resources Information Center

Greenwood, Janinka

2018-01-01

This article explores the importance of place within doctoral research. It considers place as localised, experiential, interactional, embedded in history and discourses, and often multi-faceted and fluid. With a focus on the field of education, it argues that doctoral students need to navigate between the university, the place of study and the…

Spiking Neurons in a Hierarchical Self-Organizing Map Model Can Learn to Develop Spatial and Temporal Properties of Entorhinal Grid Cells and Hippocampal Place Cells

PubMed Central

Pilly, Praveen K.; Grossberg, Stephen

2013-01-01

Medial entorhinal grid cells and hippocampal place cells provide neural correlates of spatial representation in the brain. A place cell typically fires whenever an animal is present in one or more spatial regions, or places, of an environment. A grid cell typically fires in multiple spatial regions that form a regular hexagonal grid structure extending throughout the environment. Different grid and place cells prefer spatially offset regions, with their firing fields increasing in size along the dorsoventral axes of the medial entorhinal cortex and hippocampus. The spacing between neighboring fields for a grid cell also increases along the dorsoventral axis. This article presents a neural model whose spiking neurons operate in a hierarchy of self-organizing maps, each obeying the same laws. This spiking GridPlaceMap model simulates how grid cells and place cells may develop. It responds to realistic rat navigational trajectories by learning grid cells with hexagonal grid firing fields of multiple spatial scales and place cells with one or more firing fields that match neurophysiological data about these cells and their development in juvenile rats. The place cells represent much larger spaces than the grid cells, which enable them to support navigational behaviors. Both self-organizing maps amplify and learn to categorize the most frequent and energetic co-occurrences of their inputs. The current results build upon a previous rate-based model of grid and place cell learning, and thus illustrate a general method for converting rate-based adaptive neural models, without the loss of any of their analog properties, into models whose cells obey spiking dynamics. New properties of the spiking GridPlaceMap model include the appearance of theta band modulation. The spiking model also opens a path for implementation in brain-emulating nanochips comprised of networks of noisy spiking neurons with multiple-level adaptive weights for controlling autonomous adaptive robots capable of spatial navigation. PMID:23577130

Are Distal and Proximal Visual Cues Equally Important during Spatial Learning in Mice? A Pilot Study of Overshadowing in the Spatial Domain

PubMed Central

Hébert, Marie; Bulla, Jan; Vivien, Denis; Agin, Véronique

2017-01-01

Animals use distal and proximal visual cues to accurately navigate in their environment, with the possibility of the occurrence of associative mechanisms such as cue competition as previously reported in honey-bees, rats, birds and humans. In this pilot study, we investigated one of the most common forms of cue competition, namely the overshadowing effect, between visual landmarks during spatial learning in mice. To this end, C57BL/6J × Sv129 mice were given a two-trial place recognition task in a T-maze, based on a novelty free-choice exploration paradigm previously developed to study spatial memory in rodents. As this procedure implies the use of different aspects of the environment to navigate (i.e., mice can perceive from each arm of the maze), we manipulated the distal and proximal visual landmarks during both the acquisition and retrieval phases. Our prospective findings provide a first set of clues in favor of the occurrence of an overshadowing between visual cues during a spatial learning task in mice when both types of cues are of the same modality but at varying distances from the goal. In addition, the observed overshadowing seems to be non-reciprocal, as distal visual cues tend to overshadow the proximal ones when competition occurs, but not vice versa. The results of the present study offer a first insight about the occurrence of associative mechanisms during spatial learning in mice, and may open the way to promising new investigations in this area of research. Furthermore, the methodology used in this study brings a new, useful and easy-to-use tool for the investigation of perceptive, cognitive and/or attentional deficits in rodents. PMID:28634446

Spatial Memory Engram in the Mouse Retrosplenial Cortex.

PubMed

Milczarek, Michal M; Vann, Seralynne D; Sengpiel, Frank

2018-06-18

Memory relies on lasting adaptations of neuronal properties elicited by stimulus-driven plastic changes [1]. The strengthening (and weakening) of synapses results in the establishment of functional ensembles. It is presumed that such ensembles (or engrams) are activated during memory acquisition and re-activated upon memory retrieval. The retrosplenial cortex (RSC) has emerged as a key brain area supporting memory [2], including episodic and topographical memory in humans [3-5], as well as spatial memory in rodents [6, 7]. Dysgranular RSC is densely connected with dorsal stream visual areas [8] and contains place-like and head-direction cells, making it a prime candidate for integrating navigational information [9]. While previous reports [6, 10] describe the recruitment of RSC ensembles during navigational tasks, such ensembles have never been tracked long enough to provide evidence of stable engrams and have not been related to the retention of long-term memory. Here, we used in vivo 2-photon imaging to analyze patterns of activity of over 6,000 neurons within dysgranular RSC. Eight mice were trained on a spatial memory task. Learning was accompanied by the gradual emergence of a context-specific pattern of neuronal activity over a 3-week period, which was re-instated upon retrieval more than 3 weeks later. The stability of this memory engram was predictive of the degree of forgetting; more stable engrams were associated with better performance. This provides direct evidence for the interdependence of spatial memory consolidation and RSC engram formation. Our results demonstrate the participation of RSC in spatial memory storage at the level of neuronal ensembles. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Route-Learning Strategies in Typical and Atypical Development; Eye Tracking Reveals Atypical Landmark Selection in Williams Syndrome

ERIC Educational Resources Information Center

Farran, E. K.; Formby, S.; Daniyal, F.; Holmes, T.; Van Herwegen, J.

2016-01-01

Background: Successful navigation is crucial to everyday life. Individuals with Williams syndrome (WS) have impaired spatial abilities. This includes a deficit in spatial navigation abilities such as learning the route from A to B. To-date, to determine whether participants attend to landmarks when learning a route, landmark recall tasks have been…

A Secure and Privacy-Preserving Navigation Scheme Using Spatial Crowdsourcing in Fog-Based VANETs

PubMed Central

Wang, Lingling; Liu, Guozhu; Sun, Lijun

2017-01-01

Fog-based VANETs (Vehicular ad hoc networks) is a new paradigm of vehicular ad hoc networks with the advantages of both vehicular cloud and fog computing. Real-time navigation schemes based on fog-based VANETs can promote the scheme performance efficiently. In this paper, we propose a secure and privacy-preserving navigation scheme by using vehicular spatial crowdsourcing based on fog-based VANETs. Fog nodes are used to generate and release the crowdsourcing tasks, and cooperatively find the optimal route according to the real-time traffic information collected by vehicles in their coverage areas. Meanwhile, the vehicle performing the crowdsourcing task can get a reasonable reward. The querying vehicle can retrieve the navigation results from each fog node successively when entering its coverage area, and follow the optimal route to the next fog node until it reaches the desired destination. Our scheme fulfills the security and privacy requirements of authentication, confidentiality and conditional privacy preservation. Some cryptographic primitives, including the Elgamal encryption algorithm, AES, randomized anonymous credentials and group signatures, are adopted to achieve this goal. Finally, we analyze the security and the efficiency of the proposed scheme. PMID:28338620

A Secure and Privacy-Preserving Navigation Scheme Using Spatial Crowdsourcing in Fog-Based VANETs.

PubMed

Wang, Lingling; Liu, Guozhu; Sun, Lijun

2017-03-24

Fog-based VANETs (Vehicular ad hoc networks) is a new paradigm of vehicular ad hoc networks with the advantages of both vehicular cloud and fog computing. Real-time navigation schemes based on fog-based VANETs can promote the scheme performance efficiently. In this paper, we propose a secure and privacy-preserving navigation scheme by using vehicular spatial crowdsourcing based on fog-based VANETs. Fog nodes are used to generate and release the crowdsourcing tasks, and cooperatively find the optimal route according to the real-time traffic information collected by vehicles in their coverage areas. Meanwhile, the vehicle performing the crowdsourcing task can get a reasonable reward. The querying vehicle can retrieve the navigation results from each fog node successively when entering its coverage area, and follow the optimal route to the next fog node until it reaches the desired destination. Our scheme fulfills the security and privacy requirements of authentication, confidentiality and conditional privacy preservation. Some cryptographic primitives, including the Elgamal encryption algorithm, AES, randomized anonymous credentials and group signatures, are adopted to achieve this goal. Finally, we analyze the security and the efficiency of the proposed scheme.

Systematic methods for knowledge acquisition and expert system development

NASA Technical Reports Server (NTRS)

Belkin, Brenda L.; Stengel, Robert F.

1991-01-01

Nine cooperating rule-based systems, collectively called AUTOCREW, were designed to automate functions and decisions associated with a combat aircraft's subsystem. The organization of tasks within each system is described; performance metrics were developed to evaluate the workload of each rule base, and to assess the cooperation between the rule-bases. Each AUTOCREW subsystem is composed of several expert systems that perform specific tasks. AUTOCREW's NAVIGATOR was analyzed in detail to understand the difficulties involved in designing the system and to identify tools and methodologies that ease development. The NAVIGATOR determines optimal navigation strategies from a set of available sensors. A Navigation Sensor Management (NSM) expert system was systematically designed from Kalman filter covariance data; four ground-based, a satellite-based, and two on-board INS-aiding sensors were modeled and simulated to aid an INS. The NSM Expert was developed using the Analysis of Variance (ANOVA) and the ID3 algorithm. Navigation strategy selection is based on an RSS position error decision metric, which is computed from the covariance data. Results show that the NSM Expert predicts position error correctly between 45 and 100 percent of the time for a specified navaid configuration and aircraft trajectory. The NSM Expert adapts to new situations, and provides reasonable estimates of hybrid performance. The systematic nature of the ANOVA/ID3 method makes it broadly applicable to expert system design when experimental or simulation data is available.

Learnable Interfaces--Leveraging Navigation by Design

ERIC Educational Resources Information Center

Swanson, Kari Gunvaldson

2012-01-01

Complex productivity applications that integrate tasks in the workplace are becoming more common. Usability typically focuses on short-term, immediate measures of task performance. This study incorporates a long-term goal of more durable learning, focusing on implicit learning (spontaneous, unplanned, usually unconscious learning as a result of…

Cognitive Support for Learning Computer-Based Tasks Using Animated Demonstration

ERIC Educational Resources Information Center

Chen, Chun-Ying

2016-01-01

This study investigated the influence of cognitive support for learning computer-based tasks using animated demonstration (AD) on instructional efficiency. Cognitive support included (1) segmentation and learner control introducing interactive devices that allow content sequencing through a navigational menu, and content pacing through stop and…

Contributions of Hippocampus and Striatum to Memory-Guided Behavior Depend on Past Experience

PubMed Central

2016-01-01

The hippocampal and striatal memory systems are thought to operate independently and in parallel in supporting cognitive memory and habits, respectively. Much of the evidence for this principle comes from double dissociation data, in which damage to brain structure A causes deficits in Task 1 but not Task 2, whereas damage to structure B produces the reverse pattern of effects. Typically, animals are explicitly trained in one task. Here, we investigated whether this principle continues to hold when animals concurrently learn two types of tasks. Rats were trained on a plus maze in either a spatial navigation or a cue–response task (sequential training), whereas a third set of rats acquired both (concurrent training). Subsequently, the rats underwent either sham surgery or neurotoxic lesions of the hippocampus (HPC), medial dorsal striatum (DSM), or lateral dorsal striatum (DSL), followed by retention testing. Finally, rats in the sequential training condition also acquired the novel “other” task. When rats learned one task, HPC and DSL selectively supported spatial navigation and cue response, respectively. However, when rats learned both tasks, HPC and DSL additionally supported the behavior incongruent with the processing style of the corresponding memory system. Thus, in certain conditions, the hippocampal and striatal memory systems can operate cooperatively and in synergism. DSM significantly contributed to performance regardless of task or training procedure. Experience with the cue–response task facilitated subsequent spatial learning, whereas experience with spatial navigation delayed both concurrent and subsequent response learning. These findings suggest that there are multiple operational principles that govern memory networks. SIGNIFICANCE STATEMENT Currently, we distinguish among several types of memories, each supported by a distinct neural circuit. The memory systems are thought to operate independently and in parallel. Here, we demonstrate that the hippocampus and the dorsal striatum memory systems operate independently and in parallel when rats learn one type of task at a time, but interact cooperatively and in synergism when rats concurrently learn two types of tasks. Furthermore, new learning is modulated by past experiences. These results can be explained by a model in which independent and parallel information processing that occurs in the separate memory-related neural circuits is supplemented by information transfer between the memory systems at the level of the cortex. PMID:27307234

Contributions of Hippocampus and Striatum to Memory-Guided Behavior Depend on Past Experience.

PubMed

Ferbinteanu, Janina

2016-06-15

The hippocampal and striatal memory systems are thought to operate independently and in parallel in supporting cognitive memory and habits, respectively. Much of the evidence for this principle comes from double dissociation data, in which damage to brain structure A causes deficits in Task 1 but not Task 2, whereas damage to structure B produces the reverse pattern of effects. Typically, animals are explicitly trained in one task. Here, we investigated whether this principle continues to hold when animals concurrently learn two types of tasks. Rats were trained on a plus maze in either a spatial navigation or a cue-response task (sequential training), whereas a third set of rats acquired both (concurrent training). Subsequently, the rats underwent either sham surgery or neurotoxic lesions of the hippocampus (HPC), medial dorsal striatum (DSM), or lateral dorsal striatum (DSL), followed by retention testing. Finally, rats in the sequential training condition also acquired the novel "other" task. When rats learned one task, HPC and DSL selectively supported spatial navigation and cue response, respectively. However, when rats learned both tasks, HPC and DSL additionally supported the behavior incongruent with the processing style of the corresponding memory system. Thus, in certain conditions, the hippocampal and striatal memory systems can operate cooperatively and in synergism. DSM significantly contributed to performance regardless of task or training procedure. Experience with the cue-response task facilitated subsequent spatial learning, whereas experience with spatial navigation delayed both concurrent and subsequent response learning. These findings suggest that there are multiple operational principles that govern memory networks. Currently, we distinguish among several types of memories, each supported by a distinct neural circuit. The memory systems are thought to operate independently and in parallel. Here, we demonstrate that the hippocampus and the dorsal striatum memory systems operate independently and in parallel when rats learn one type of task at a time, but interact cooperatively and in synergism when rats concurrently learn two types of tasks. Furthermore, new learning is modulated by past experiences. These results can be explained by a model in which independent and parallel information processing that occurs in the separate memory-related neural circuits is supplemented by information transfer between the memory systems at the level of the cortex. Copyright © 2016 the authors 0270-6474/16/366459-12$15.00/0.

Mutinous Colonialism: Navigating Self-Other Dichotomy in Octavia Butler's "Survivor"

ERIC Educational Resources Information Center

JubouriAl-Ogaili, Thamer Amer; Babaee, Ruzbeh

2015-01-01

This article examines the self-other relationship in Octavia Butler's novel "Survivor" (1978). This relationship incarnates the colonial powers brought about the missionaries in their early advent in the fictional place known as "Earth". This place is the foundational setting where the main events take place. The study focuses…

Private Graphs - Access Rights on Graphs for Seamless Navigation

NASA Astrophysics Data System (ADS)

Dorner, W.; Hau, F.; Pagany, R.

2016-06-01

After the success of GNSS (Global Navigational Satellite Systems) and navigation services for public streets, indoor seems to be the next big development in navigational services, relying on RTLS - Real Time Locating Services (e.g. WIFI) and allowing seamless navigation. In contrast to navigation and routing services on public streets, seamless navigation will cause an additional challenge: how to make routing data accessible to defined users or restrict access rights for defined areas or only to parts of the graph to a defined user group? The paper will present case studies and data from literature, where seamless and especially indoor navigation solutions are presented (hospitals, industrial complexes, building sites), but the problem of restricted access rights was only touched from a real world, but not a technical perspective. The analysis of case studies will show, that the objective of navigation and the different target groups for navigation solutions will demand well defined access rights and require solutions, how to make only parts of a graph to a user or application available to solve a navigational task. The paper will therefore introduce the concept of private graphs, which is defined as a graph for navigational purposes covering the street, road or floor network of an area behind a public street and suggest different approaches how to make graph data for navigational purposes available considering access rights and data protection, privacy and security issues as well.

An assessment of patient navigator activities in breast cancer patient navigation programs using a nine-principle framework.

PubMed

Gunn, Christine M; Clark, Jack A; Battaglia, Tracy A; Freund, Karen M; Parker, Victoria A

2014-10-01

To determine how closely a published model of navigation reflects the practice of navigation in breast cancer patient navigation programs. Observational field notes describing patient navigator activities collected from 10 purposefully sampled, foundation-funded breast cancer navigation programs in 2008-2009. An exploratory study evaluated a model framework for patient navigation published by Harold Freeman by using an a priori coding scheme based on model domains. Field notes were compiled and coded. Inductive codes were added during analysis to characterize activities not included in the original model. Programs were consistent with individual-level principles representing tasks focused on individual patients. There was variation with respect to program-level principles that related to program organization and structure. Program characteristics such as the use of volunteer or clinical navigators were identified as contributors to patterns of model concordance. This research provides a framework for defining the navigator role as focused on eliminating barriers through the provision of individual-level interventions. The diversity observed at the program level in these programs was a reflection of implementation according to target population. Further guidance may be required to assist patient navigation programs to define and tailor goals and measurement to community needs. © Health Research and Educational Trust.

An Assessment of Patient Navigator Activities in Breast Cancer Patient Navigation Programs Using a Nine-Principle Framework

PubMed Central

Gunn, Christine M; Clark, Jack A; Battaglia, Tracy A; Freund, Karen M; Parker, Victoria A

2014-01-01

Objective To determine how closely a published model of navigation reflects the practice of navigation in breast cancer patient navigation programs. Data Source Observational field notes describing patient navigator activities collected from 10 purposefully sampled, foundation-funded breast cancer navigation programs in 2008–2009. Study Design An exploratory study evaluated a model framework for patient navigation published by Harold Freeman by using an a priori coding scheme based on model domains. Data Collection Field notes were compiled and coded. Inductive codes were added during analysis to characterize activities not included in the original model. Principal Findings Programs were consistent with individual-level principles representing tasks focused on individual patients. There was variation with respect to program-level principles that related to program organization and structure. Program characteristics such as the use of volunteer or clinical navigators were identified as contributors to patterns of model concordance. Conclusions This research provides a framework for defining the navigator role as focused on eliminating barriers through the provision of individual-level interventions. The diversity observed at the program level in these programs was a reflection of implementation according to target population. Further guidance may be required to assist patient navigation programs to define and tailor goals and measurement to community needs. PMID:24820445

Application of parallelized software architecture to an autonomous ground vehicle

NASA Astrophysics Data System (ADS)

Shakya, Rahul; Wright, Adam; Shin, Young Ho; Momin, Orko; Petkovsek, Steven; Wortman, Paul; Gautam, Prasanna; Norton, Adam

2011-01-01

This paper presents improvements made to Q, an autonomous ground vehicle designed to participate in the Intelligent Ground Vehicle Competition (IGVC). For the 2010 IGVC, Q was upgraded with a new parallelized software architecture and a new vision processor. Improvements were made to the power system reducing the number of batteries required for operation from six to one. In previous years, a single state machine was used to execute the bulk of processing activities including sensor interfacing, data processing, path planning, navigation algorithms and motor control. This inefficient approach led to poor software performance and made it difficult to maintain or modify. For IGVC 2010, the team implemented a modular parallel architecture using the National Instruments (NI) LabVIEW programming language. The new architecture divides all the necessary tasks - motor control, navigation, sensor data collection, etc. into well-organized components that execute in parallel, providing considerable flexibility and facilitating efficient use of processing power. Computer vision is used to detect white lines on the ground and determine their location relative to the robot. With the new vision processor and some optimization of the image processing algorithm used last year, two frames can be acquired and processed in 70ms. With all these improvements, Q placed 2nd in the autonomous challenge.

Flexible Multi agent Algorithm for Distributed Decision Making

DTIC Science & Technology

2015-01-01

How, J. P. Consensus - Based Auction Approaches for Decentralized task Assignment. Proceedings of the AIAA Guidance, Navigation, and Control...G. ; Kim, Y. Market- based Decentralized Task Assignment for Cooperative UA V Mission Including Rendezvous. Proceedings of the AIAA Guidance...scalable and adaptable to a variety of specific mission tasks . Additionally, the algorithm could easily be adapted for use on land or sea- based systems

Surgical task analysis of simulated laparoscopic cholecystectomy with a navigation system.

PubMed

Sugino, T; Kawahira, H; Nakamura, R

2014-09-01

   Advanced surgical procedures, which have become complex and difficult, increase the burden of surgeons. Quantitative analysis of surgical procedures can improve training, reduce variability, and enable optimization of surgical procedures. To this end, a surgical task analysis system was developed that uses only surgical navigation information.    Division of the surgical procedure, task progress analysis, and task efficiency analysis were done. First, the procedure was divided into five stages. Second, the operating time and progress rate were recorded to document task progress during specific stages, including the dissecting task. Third, the speed of the surgical instrument motion (mean velocity and acceleration), as well as the size and overlap ratio of the approximate ellipse of the location log data distribution, was computed to estimate the task efficiency during each stage. These analysis methods were evaluated based on experimental validation with two groups of surgeons, i.e., skilled and "other" surgeons. The performance metrics and analytical parameters included incidents during the operation, the surgical environment, and the surgeon's skills or habits.    Comparison of groups revealed that skilled surgeons tended to perform the procedure in less time and involved smaller regions; they also manipulated the surgical instruments more gently.    Surgical task analysis developed for quantitative assessment of surgical procedures and surgical performance may provide practical methods and metrics for objective evaluation of surgical expertise.

Isolated core vs. superficial cooling effects on virtual maze navigation.

PubMed

Payne, Jennifer; Cheung, Stephen S

2007-07-01

Cold impairs cognitive performance and is a common occurrence in many survival situations. Altered behavior patterns due to impaired navigation abilities in cold environments are potential problems in lost-person situations. We investigated the separate effects of low core temperature and superficial cooling on a spatially demanding virtual navigation task. There were 12 healthy men who were passively cooled via 15 degrees C water immersion to a core temperature of 36.0 degrees C, then transferred to a warm (40 degrees C) water bath to eliminate superficial shivering while completing a series of 20 virtual computer mazes. In a control condition, subjects rested in a thermoneutral (approximately 35 degrees C) bath for a time-matched period before being transferred to a warm bath for testing. Superficial cooling and distraction were achieved by whole-body immersion in 35 degree water for a time-matched period, followed by lower leg immersion in 10 degree C water for the duration of the navigational tests. Mean completion time and mean error scores for the mazes were not significantly different (p > 0.05) across the core cooling (16.59 +/- 11.54 s, 0.91 +/- 1.86 errors), control (15.40 +/- 8.85 s, 0.82 +/- 1.76 errors), and superficial cooling (15.19 +/- 7.80 s, 0.77 +/- 1.40 errors) conditions. Separately reducing core temperature or increasing cold sensation in the lower extremities did not influence performance on virtual computer mazes, suggesting that navigation is more resistive to cooling than other, simpler cognitive tasks. Further research is warranted to explore navigational ability at progressively lower core and skin temperatures, and in different populations.

The Effects of Restricted Peripheral Field-of-View on Spatial Learning while Navigating.

PubMed

Barhorst-Cates, Erica M; Rand, Kristina M; Creem-Regehr, Sarah H

2016-01-01

Recent work with simulated reductions in visual acuity and contrast sensitivity has found decrements in survey spatial learning as well as increased attentional demands when navigating, compared to performance with normal vision. Given these findings, and previous work showing that peripheral field loss has been associated with impaired mobility and spatial memory for room-sized spaces, we investigated the role of peripheral vision during navigation using a large-scale spatial learning paradigm. First, we aimed to establish the magnitude of spatial memory errors at different levels of field restriction. Second, we tested the hypothesis that navigation under these different levels of restriction would use additional attentional resources. Normally sighted participants walked on novel real-world paths wearing goggles that restricted the field-of-view (FOV) to severe (15°, 10°, 4°, or 0°) or mild angles (60°) and then pointed to remembered target locations using a verbal reporting measure. They completed a concurrent auditory reaction time task throughout each path to measure cognitive load. Only the most severe restrictions (4° and blindfolded) showed impairment in pointing error compared to the mild restriction (within-subjects). The 10° and 4° conditions also showed an increase in reaction time on the secondary attention task, suggesting that navigating with these extreme peripheral field restrictions demands the use of limited cognitive resources. This comparison of different levels of field restriction suggests that although peripheral field loss requires the actor to use more attentional resources while navigating starting at a less extreme level (10°), spatial memory is not negatively affected until the restriction is very severe (4°). These results have implications for understanding of the mechanisms underlying spatial learning during navigation and the approaches that may be taken to develop assistance for navigation with visual impairment.

Spinning in the Scanner: Neural Correlates of Virtual Reorientation

ERIC Educational Resources Information Center

Sutton, Jennifer E.; Joanisse, Marc F.; Newcombe, Nora S.

2010-01-01

Recent studies have used spatial reorientation task paradigms to identify underlying cognitive mechanisms of navigation in children, adults, and a range of animal species. Despite broad interest in this task across disciplines, little is known about the brain bases of reorientation. We used functional magnetic resonance imaging to examine neural…

Suboptimal Tradeoffs in Information Seeking

ERIC Educational Resources Information Center

Fu, Wai-Tat; Gray, Wayne D.

2006-01-01

Explicit information-seeking actions are needed to evaluate alternative actions in problem-solving tasks. Information-seeking costs are often traded off against the utility of information. We present three experiments that show how subjects adapt to the cost and information structures of environments in a map-navigation task. We found that…

The real-world navigator

NASA Technical Reports Server (NTRS)

Balabanovic, Marko; Becker, Craig; Morse, Sarah K.; Nourbakhsh, Illah R.

1994-01-01

The success of every mobile robot application hinges on the ability to navigate robustly in the real world. The problem of robust navigation is separable from the challenges faced by any particular robot application. We offer the Real-World Navigator as a solution architecture that includes a path planner, a map-based localizer, and a motion control loop that combines reactive avoidance modules with deliberate goal-based motion. Our architecture achieves a high degree of reliability by maintaining and reasoning about an explicit description of positional uncertainty. We provide two implementations of real-world robot systems that incorporate the Real-World Navigator. The Vagabond Project culminated in a robot that successfully navigated a portion of the Stanford University campus. The Scimmer project developed successful entries for the AIAA 1993 Robotics Competition, placing first in one of the two contests entered.

Low cost omega navigation receiver

NASA Technical Reports Server (NTRS)

Lilley, R. W.

1974-01-01

The development of a low cost Omega navigation receiver is discussed. Emphasis is placed on the completion and testing of a modular, multipurpose Omega receiver which utilizes a digital memory-aided, phase-locked loop to provide phase measurement data to a variety of applications interfaces. The functional units contained in the prototype device are described. The receiver is capable of receiving and storing phase measurements for up to eight Omega signals and computes two switch-selectable lines of position, displaying this navigation data in chart-recorded form.

Electronic Health Records Place 1st at Indy 500

MedlinePlus

... Navigation Bar Home Current Issue Past Issues EHR Electronic Health Records Place 1st at Indy 500 Past ... last May's Indy 500 had thousands of personal Electronic Health Records on hand for those attending—and ...

Autonomous navigation and mobility for a planetary rover

NASA Technical Reports Server (NTRS)

Miller, David P.; Mishkin, Andrew H.; Lambert, Kenneth E.; Bickler, Donald; Bernard, Douglas E.

1989-01-01

This paper presents an overview of the onboard subsystems that will be used in guiding a planetary rover. Particular emphasis is placed on the planning and sensing systems and their associated costs, particularly in computation. Issues that will be used in evaluating trades between the navigation system and mobility system are also presented.

How Do (Some) People Make a Cognitive Map? Routes, Places, and Working Memory

ERIC Educational Resources Information Center

Weisberg, Steven M.; Newcombe, Nora S.

2016-01-01

Research on the existence of cognitive maps and on the cognitive processes that support effective navigation has often focused on functioning across individuals. However, there are pronounced individual differences in navigation proficiency, which need to be explained and which can illuminate our understanding of cognitive maps and effective…

33 CFR 155.470 - Prohibited spaces.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Prohibited spaces. 155.470... Prohibited spaces. (a) In a ship of 400 gross tons and above, for which the building contract is placed after... material in any space forward of a collision bulkhead except: (1) For a ship constructed after June 30...

33 CFR 155.470 - Prohibited spaces.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Prohibited spaces. 155.470... Prohibited spaces. (a) In a ship of 400 gross tons and above, for which the building contract is placed after... material in any space forward of a collision bulkhead except: (1) For a ship constructed after June 30...

33 CFR 155.470 - Prohibited spaces.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Prohibited spaces. 155.470... Prohibited spaces. (a) In a ship of 400 gross tons and above, for which the building contract is placed after... material in any space forward of a collision bulkhead except: (1) For a ship constructed after June 30...

33 CFR 155.470 - Prohibited spaces.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Prohibited spaces. 155.470... Prohibited spaces. (a) In a ship of 400 gross tons and above, for which the building contract is placed after... material in any space forward of a collision bulkhead except: (1) For a ship constructed after June 30...

33 CFR 155.470 - Prohibited spaces.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Prohibited spaces. 155.470... Prohibited spaces. (a) In a ship of 400 gross tons and above, for which the building contract is placed after... material in any space forward of a collision bulkhead except: (1) For a ship constructed after June 30...

33 CFR 127.1319 - Transfer of LHG.

Code of Federal Regulations, 2014 CFR

2014-07-01

... operator of a waterfront facility handling LHG shall notify the COTP of the time and place of each transfer...) The person in charge supervises transfers only to or from one vessel at a time unless authorized by... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Transfer of LHG. 127.1319 Section...

33 CFR 127.1319 - Transfer of LHG.

Code of Federal Regulations, 2012 CFR

2012-07-01

... operator of a waterfront facility handling LHG shall notify the COTP of the time and place of each transfer...) The person in charge supervises transfers only to or from one vessel at a time unless authorized by... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Transfer of LHG. 127.1319 Section...

33 CFR 127.1319 - Transfer of LHG.

Code of Federal Regulations, 2011 CFR

2011-07-01

... operator of a waterfront facility handling LHG shall notify the COTP of the time and place of each transfer...) The person in charge supervises transfers only to or from one vessel at a time unless authorized by... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Transfer of LHG. 127.1319 Section...

33 CFR 127.1319 - Transfer of LHG.

Code of Federal Regulations, 2010 CFR

2010-07-01

... operator of a waterfront facility handling LHG shall notify the COTP of the time and place of each transfer...) The person in charge supervises transfers only to or from one vessel at a time unless authorized by... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Transfer of LHG. 127.1319 Section...

33 CFR 127.1319 - Transfer of LHG.

Code of Federal Regulations, 2013 CFR

2013-07-01

... operator of a waterfront facility handling LHG shall notify the COTP of the time and place of each transfer...) The person in charge supervises transfers only to or from one vessel at a time unless authorized by... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Transfer of LHG. 127.1319 Section...

78 FR 59237 - Regulated Navigation Area-Weymouth Fore River, Fore River Bridge Construction, Weymouth and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-26

...-AA11 Regulated Navigation Area--Weymouth Fore River, Fore River Bridge Construction, Weymouth and... vicinity of the Fore River Bridge (Mile 3.5) between Weymouth and Quincy, MA. This rule will place temporary speed, wake, and entry restrictions on vessels during bridge replacement operations. This rule is...

33 CFR 100.1306 - National Maritime Week Tugboat Races, Seattle, WA.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Races, Seattle, WA. 100.1306 Section 100.1306 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Maritime Week Tugboat Races, Seattle, WA. (a) Regulated Area. A regulated area is established on that... approximately 650 yards into Elliott Bay. Temporary floating markers will be placed by the race sponsors to...

33 CFR 100.1306 - National Maritime Week Tugboat Races, Seattle, WA.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Races, Seattle, WA. 100.1306 Section 100.1306 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Maritime Week Tugboat Races, Seattle, WA. (a) Regulated Area. A regulated area is established on that... approximately 650 yards into Elliott Bay. Temporary floating markers will be placed by the race sponsors to...

33 CFR 100.1306 - National Maritime Week Tugboat Races, Seattle, WA.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Races, Seattle, WA. 100.1306 Section 100.1306 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Maritime Week Tugboat Races, Seattle, WA. (a) Regulated Area. A regulated area is established on that... approximately 650 yards into Elliott Bay. Temporary floating markers will be placed by the race sponsors to...

33 CFR 100.1306 - National Maritime Week Tugboat Races, Seattle, WA.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Races, Seattle, WA. 100.1306 Section 100.1306 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Maritime Week Tugboat Races, Seattle, WA. (a) Regulated Area. A regulated area is established on that... approximately 650 yards into Elliott Bay. Temporary floating markers will be placed by the race sponsors to...

Spatial cell firing during virtual navigation of open arenas by head-restrained mice.

PubMed

Chen, Guifen; King, John Andrew; Lu, Yi; Cacucci, Francesca; Burgess, Neil

2018-06-18

We present a mouse virtual reality (VR) system which restrains head-movements to horizontal rotations, compatible with multi-photon imaging. This system allows expression of the spatial navigation and neuronal firing patterns characteristic of real open arenas (R). Comparing VR to R: place and grid, but not head-direction, cell firing had broader spatial tuning; place, but not grid, cell firing was more directional; theta frequency increased less with running speed; whereas increases in firing rates with running speed and place and grid cells' theta phase precession were similar. These results suggest that the omni-directional place cell firing in R may require local-cues unavailable in VR, and that the scale of grid and place cell firing patterns, and theta frequency, reflect translational motion inferred from both virtual (visual and proprioceptive) and real (vestibular translation and extra-maze) cues. By contrast, firing rates and theta phase precession appear to reflect visual and proprioceptive cues alone. © 2018, Chen et al.

How providing more or less time to solve a cognitive task interferes with upright stance control; a posturographic analysis on healthy young adults.

PubMed

Rougier, Patrice R; Bonnet, Cédrick T

2016-06-01

Contrasted postural effects have been reported in dual-task protocols associating balance control and cognitive task that could be explained by the nature and the relative difficulty of the cognitive task and the biomechanical significance of the force platform data. To better assess their respective role, eleven healthy young adults were required to stand upright quietly on a force platform while concomitantly solving mental-calculation or mental-navigation cognitive tasks. Various levels of difficulty were applied by adjusting the velocity rate at which the instructions were provided to the subject according to his/her maximal capacities measured beforehand. A condition without any concomitant cognitive task was added to constitute a baseline behavior. Two basic components, the horizontal center-of-gravity movements and the horizontal difference between center-of-gravity and center-of-pressures were computed from the complex center-of-pressure recorded movements. It was hypothesized that increasing the delay should infer less interaction between postural control and task solution. The results indicate that both mental-calculation and mental-navigation tasks induce reduced amplitudes for the center-of-pressure minus center-of-gravity movements, only along the mediolateral axis, whereas center-of-gravity movements were not affected, suggesting that different circuits are involved in the central nervous system to control these two movements. Moreover, increasing the delays task does not infer any effect for both movements. Since center-of-pressure minus center-of-gravity expresses the horizontal acceleration communicated to the center-of-gravity, one may assume that the control of the latter should be facilitated in dual-tasks conditions, inferring reduced center-of-gravity movements, which is not seen in our results. This lack of effect should be thus interpreted as a modification in the control of these center-of-gravity movements. Taken together, these results emphasized how undisturbed upright stance control can be impacted by mental tasks requiring attention, whatever their nature (calculation or navigation) and their relative difficulty. Depending on the provided instructions, i.e. focusing our attention on body movements or on the opposite diverting this attention toward other objectives, the evaluation of upright stance control capacities might be drastically altered. Copyright © 2016. Published by Elsevier B.V.

A Brief Nap Is Beneficial for Human Route-Learning: The Role of Navigation Experience and EEG Spectral Power

ERIC Educational Resources Information Center

Wamsley, Erin J.; Tucker, Matthew A.; Payne, Jessica D.; Stickgold, Robert

2010-01-01

Here, we examined the effect of a daytime nap on changes in virtual maze performance across a single day. Participants either took a short nap or remained awake following training on a virtual maze task. Post-training sleep provided a clear performance benefit at later retest, but only for those participants with prior experience navigating in a…

Defense Science Board Task Force on The Future of the Global Positioning System

DTIC Science & Technology

2005-10-01

interference. Incorporate a fully reprogrammable Navigation Payload aboard GPS satellites as soon as practicable to enable future flexibility in signal...its use increases in automobiles , it is becoming a significant factor in E-911-type situations, where emergency vehicles are dispatched to accident...mitigation for GPS against both intentional and unintentional interference. Incorporate a fully reprogrammable Navigation Payload aboard GPS

Post-test navigation data analysis techniques for the shuttle ALT

NASA Technical Reports Server (NTRS)

1975-01-01

Postflight test analysis data processing techniques for shuttle approach and landing tests (ALT) navigation data are defined. Postfight test processor requirements are described along with operational and design requirements, data input requirements, and software test requirements. The postflight test data processing is described based on the natural test sequence: quick-look analysis, postflight navigation processing, and error isolation processing. Emphasis is placed on the tradeoffs that must remain open and subject to analysis until final definition is achieved in the shuttle data processing system and the overall ALT plan. A development plan for the implementation of the ALT postflight test navigation data processing system is presented. Conclusions are presented.

The effect of extended sensory range via the EyeCane sensory substitution device on the characteristics of visionless virtual navigation.

PubMed

Maidenbaum, Shachar; Levy-Tzedek, Shelly; Chebat, Daniel Robert; Namer-Furstenberg, Rinat; Amedi, Amir

2014-01-01

Mobility training programs for helping the blind navigate through unknown places with a White-Cane significantly improve their mobility. However, what is the effect of new assistive technologies, offering more information to the blind user, on the underlying premises of these programs such as navigation patterns? We developed the virtual-EyeCane, a minimalistic sensory substitution device translating single-point-distance into auditory cues identical to the EyeCane's in the real world. We compared performance in virtual environments when using the virtual-EyeCane, a virtual-White-Cane, no device and visual navigation. We show that the characteristics of virtual-EyeCane navigation differ from navigation with a virtual-White-Cane or no device, and that virtual-EyeCane users complete more levels successfully, taking shorter paths and with less collisions than these groups, and we demonstrate the relative similarity of virtual-EyeCane and visual navigation patterns. This suggests that additional distance information indeed changes navigation patterns from virtual-White-Cane use, and brings them closer to visual navigation.

Biological sex influences learning strategy preference and muscarinic receptor binding in specific brain regions of prepubertal rats.

PubMed

Grissom, Elin M; Hawley, Wayne R; Hodges, Kelly S; Fawcett-Patel, Jessica M; Dohanich, Gary P

2013-04-01

According to the theory of multiple memory systems, specific brain regions interact to determine how the locations of goals are learned when rodents navigate a spatial environment. A number of factors influence the type of strategy used by rodents to remember the location of a given goal in space, including the biological sex of the learner. We recently found that prior to puberty male rats preferred a striatum-dependent stimulus-response strategy over a hippocampus-dependent place strategy when solving a dual-solution task, while age-matched females showed no strategy preference. Because the cholinergic system has been implicated in learning strategy and is known to be sexually dimorphic prior to puberty, we explored the relationship between learning strategy and muscarinic receptor binding in specific brain regions of prepubertal males and female rats. We confirmed our previous finding that at 28 days of age a significantly higher proportion of prepubertal males preferred a stimulus-response learning strategy than a place strategy to solve a dual-solution visible platform water maze task. Equal proportions of prepubertal females preferred stimulus-response or place strategies. Profiles of muscarinic receptor binding as assessed by autoradiography varied according to strategy preference. Regardless of biological sex, prepubertal rats that preferred stimulus-response strategy exhibited lower ratios of muscarinic receptor binding in the hippocampus relative to the dorsolateral striatum compared to rats that preferred place strategy. Importantly, much of the variance in this ratio was related to differences in the ventral hippocampus to a greater extent than the dorsal hippocampus. The ratios of muscarinic receptors in the hippocampus relative to the basolateral amygdala also were lower in rats that preferred stimulus-response strategy over place strategy. Results confirm that learning strategy preference varies with biological sex in prepubertal rats with males biased toward a stimulus-response strategy, and that stimulus-response strategy is associated with lower ratios of muscarinic binding in the hippocampus relative to either the striatum or amygdala. Copyright © 2012 Wiley Periodicals, Inc.

Impaired behavior on real-world tasks following damage to the ventromedial prefrontal cortex.

PubMed

Tranel, Daniel; Hathaway-Nepple, Julie; Anderson, Steven W

2007-04-01

Patients with damage to the ventromedial prefrontal cortices (VMPC) commonly manifest blatant behavioral navigation defects in the real world, but it has been difficult to measure these impairments in the clinic or laboratory. Using a set of "strategy application" tasks, which were designed by Shallice and Burgess (1991) to be ecologically valid for detecting executive dysfunction, we investigated the hypothesis that VMPC damage would be associated with defective performance on such tasks, whereas damage outside the VMPC region would not. A group of 9 patients with bilateral VMPC damage was contrasted with comparison groups of participants with (a) prefrontal brain damage outside the VMPC region (n = 8); (b) nonprefrontal brain damage (n = 17); and (c) no brain damage (n = 20). We found support for the hypothesis: VMPC patients had more impaired performances on the strategy application tasks, especially on a Multiple Errands Test that required patients to execute a series of unstructured tasks in a real-world setting (shopping mall). The results are consistent with the notion that efficacious behavioral navigation is dependent on the VMPC region. However, the strategy application tasks were relatively time consuming and effortful, and their diagnostic yield over and above conventional executive functioning tests may not be sufficient to warrant their inclusion in standard clinical assessment.

Impaired behavior on real-world tasks following damage to the ventromedial prefrontal cortex

PubMed Central

Tranel, Daniel; Hathaway-Nepple, Julie; Anderson, Steven W.

2008-01-01

Patients with damage to the ventromedial prefrontal cortices (VMPC) commonly manifest blatant behavioral navigation defects in the real world, but it has been difficult to measure these impairments in the clinic or laboratory. Using a set of “strategy application” tasks, which were designed by Shallice and Burgess (1991) to be ecologically valid for detecting executive dysfunction, we investigated the hypothesis that VMPC damage would be associated with defective performance on such tasks, whereas damage outside the VMPC region would not. A group of 9 patients with bilateral VMPC damage was contrasted with comparison groups of participants with (a) prefrontal brain damage outside the VMPC region (n=8); (b) nonprefrontal brain damage (n=17); and (c) no brain damage (n=20). We found support for the hypothesis: VMPC patients had more impaired performances on the strategy application tasks, especially on a Multiple Errands Test that required patients to execute a series of unstructured tasks in a real-world setting (shopping mall). The results are consistent with the notion that efficacious behavioral navigation is dependent on the VMPC region. However, the strategy application tasks were relatively time consuming and effortful, and their diagnostic yield over and above conventional executive functioning tests may not be sufficient to warrant their inclusion in standard clinical assessment. PMID:17454352

Development of autonomous grasping and navigating robot

NASA Astrophysics Data System (ADS)

Kudoh, Hiroyuki; Fujimoto, Keisuke; Nakayama, Yasuichi

2015-01-01

The ability to find and grasp target items in an unknown environment is important for working robots. We developed an autonomous navigating and grasping robot. The operations are locating a requested item, moving to where the item is placed, finding the item on a shelf or table, and picking the item up from the shelf or the table. To achieve these operations, we designed the robot with three functions: an autonomous navigating function that generates a map and a route in an unknown environment, an item position recognizing function, and a grasping function. We tested this robot in an unknown environment. It achieved a series of operations: moving to a destination, recognizing the positions of items on a shelf, picking up an item, placing it on a cart with its hand, and returning to the starting location. The results of this experiment show the applicability of reducing the workforce with robots.

Cognitive Impairment Assessment through Visuospatial Memory Can Be Performed with a Modified Walking Corsi Test Using the ‘Magic Carpet’

PubMed Central

Perrochon, Anaïck; Kemoun, Gilles; Dugué, Benoit; Berthoz, Alain

2014-01-01

Background Subjects with mild cognitive impairment (MCI) have disturbances in their spatial navigation abilities and exhibit early deficits in visuospatial short-term memory. The purpose of the present study was to determine whether a quantitative (span score) and qualitative (evaluating navigation strategies used) analysis of the Corsi test (usual condition and complex navigation task) would be useful to reveal cognitive decline. Methods We evaluated the performance of 15 young adults, 21 healthy elderly subjects and 15 subjects with MCI using the electronic version of the Corsi test (the Modified Corsi Block-Tapping Test, MCBT) and the complex navigation task (the Modified Walking Corsi Test, MWCT). The MWCT, which is an adaptation of the Corsi test, assesses spatial memory when the subject walks in a complex environment. We used Richard et al.'s model [Cogn Sci 1993;17:497-529] to investigate problem-solving strategies during the Corsi tests. Results The span scores obtained on the MCBT and the MWCT were significantly lower in the healthy elderly subjects (MCBT = 5.0 ± 0.7; MWCT = 4.0 ± 0.7) and the subjects with MCI (MCBT = 4.7 ± 0.8; MWCT = 4.1 ± 0.9) than in the younger adults (MCBT = 6.2 ± 0.6; MWCT = 5.3 ± 1.0). The visuospatial working memory was more impaired in the complex navigation task (MWCT = 4.3 ± 0.9) than in the modified Corsi test (MCBT = 5.3 ± 0.8). Finally, the subjects with greater cognitive impairment were more likely to have inadequate or absence of problem-solving strategies. Conclusions Investigating the problem-solving strategies used during the MWCT appears to be a promising way to differentiate between the subjects with MCI and the healthy elderly subjects. PMID:24575112

Post-stroke unilateral spatial neglect: virtual reality-based navigation and detection tasks reveal lateralized and non-lateralized deficits in tasks of varying perceptual and cognitive demands.

PubMed

Ogourtsova, Tatiana; Archambault, Philippe S; Lamontagne, Anouk

2018-04-23

Unilateral spatial neglect (USN), a highly prevalent and disabling post-stroke impairment, has been shown to affect the recovery of locomotor and navigation skills needed for community mobility. We recently found that USN alters goal-directed locomotion in conditions of different cognitive/perceptual demands. However, sensorimotor post-stroke dysfunction (e.g. decreased walking speed) could have influenced the results. Analogous to a previously used goal-directed locomotor paradigm, a seated, joystick-driven navigation experiment, minimizing locomotor demands, was employed in individuals with and without post-stroke USN (USN+ and USN-, respectively) and healthy controls (HC). Participants (n = 15 per group) performed a seated, joystick-driven navigation and detection time task to targets 7 m away at 0°, ±15°/30° in actual (visually-guided), remembered (memory-guided) and shifting (visually-guided with representational updating component) conditions while immersed in a 3D virtual reality environment. Greater end-point mediolateral errors to left-sided targets (remembered and shifting conditions) and overall lengthier onsets in reorientation strategy (shifting condition) were found for USN+ vs. USN- and vs. HC (p < 0.05). USN+ individuals mostly overshot left targets (- 15°/- 30°). Greater delays in detection time for target locations across the visual spectrum (left, middle and right) were found in USN+ vs. USN- and HC groups (p < 0.05). USN-related attentional-perceptual deficits alter navigation abilities in memory-guided and shifting conditions, independently of post-stroke locomotor deficits. Lateralized and non-lateralized deficits in object detection are found. The employed paradigm could be considered in the design and development of sensitive and functional assessment methods for neglect; thereby addressing the drawbacks of currently used traditional paper-and-pencil tools.

Human place and response learning: navigation strategy selection, pupil size and gaze behavior.

PubMed

de Condappa, Olivier; Wiener, Jan M

2016-01-01

In this study, we examined the cognitive processes and ocular behavior associated with on-going navigation strategy choice using a route learning paradigm that distinguishes between three different wayfinding strategies: an allocentric place strategy, and the egocentric associative cue and beacon response strategies. Participants approached intersections of a known route from a variety of directions, and were asked to indicate the direction in which the original route continued. Their responses in a subset of these test trials allowed the assessment of strategy choice over the course of six experimental blocks. The behavioral data revealed an initial maladaptive bias for a beacon response strategy, with shifts in favor of the optimal configuration place strategy occurring over the course of the experiment. Response time analysis suggests that the configuration strategy relied on spatial transformations applied to a viewpoint-dependent spatial representation, rather than direct access to an allocentric representation. Furthermore, pupillary measures reflected the employment of place and response strategies throughout the experiment, with increasing use of the more cognitively demanding configuration strategy associated with increases in pupil dilation. During test trials in which known intersections were approached from different directions, visual attention was directed to the landmark encoded during learning as well as the intended movement direction. Interestingly, the encoded landmark did not differ between the three navigation strategies, which is discussed in the context of initial strategy choice and the parallel acquisition of place and response knowledge.

Teaching Young Adults with Intellectual and Developmental Disabilities Community-Based Navigation Skills to Take Public Transportation.

PubMed

Price, Richard; Marsh, Abbie J; Fisher, Marisa H

2018-03-01

Facilitating the use of public transportation enhances opportunities for independent living and competitive, community-based employment for individuals with intellectual and developmental disabilities (IDD). Four young adults with IDD were taught through total-task chaining to use the Google Maps application, a self-prompting, visual navigation system, to take the bus to locations around a college campus and the community. Three of four participants learned to use Google Maps to independently navigate public transportation. Google Maps may be helpful in supporting independent travel, highlighting the importance of future research in teaching navigation skills. Learning to independently use public transportation increases access to autonomous activities, such as opportunities to work and to attend postsecondary education programs on large college campuses.Individuals with IDD can be taught through chaining procedures to use the Google Maps application to navigate public transportation.Mobile map applications are an effective and functional modern tool that can be used to teach community navigation.

Should Animals Navigating Over Short Distances Switch to a Magnetic Compass Sense?

PubMed Central

Wyeth, Russell C.

2010-01-01

Magnetoreception can play a substantial role in long distance navigation by animals. I hypothesize that locomotion guided by a magnetic compass sense could also play a role in short distance navigation. Animals identify mates, prey, or other short distance navigational goals using different sensory modalities (olfaction, vision, audition, etc.) to detect sensory cues associated with those goals. In conditions where these cues become unreliable for navigation (due to flow changes, obstructions, noise interference, etc.), switching to a magnetic compass sense to guide locomotion toward the navigational goals could be beneficial. Using simulations based on known locomotory and flow parameters, I show this strategy has strong theoretical benefits for the nudibranch mollusk Tritonia diomedea navigating toward odor sources in variable flow. A number of other animals may garner similar benefits, particularly slow-moving species in environments with rapidly changing cues relevant for navigation. Faster animals might also benefit from switching to a magnetic compass sense, provided the initial cues used for navigation (acoustic signals, odors, etc.) are intermittent or change rapidly enough that the entire navigation behavior cannot be guided by a continuously detectable cue. Examination of the relative durations of navigational tasks, the persistence of navigational cues, and the stability of both navigators and navigational targets will identify candidates with the appropriate combination of unreliable initial cues and relatively immobile navigational goals for which this hypothetical behavior could be beneficial. Magnetic manipulations can then test whether a switch to a magnetic compass sense occurs. This hypothesis thus provides an alternative when considering the behavioral significance of a magnetic compass sense in animals. PMID:20740070

Heutagogic approach to developing capable learners.

PubMed

Abraham, Reem Rachel; Komattil, Ramnarayan

2017-03-01

The twenty-first century higher education sector has come a long way after undergoing continuous metamorphosis from pedagogy to andragogy. Most of the educational approaches adopted in medical schools are directed towards developing more of competencies and less of capability, which is the ability to use competencies in novel contexts. Competencies alone are not sufficient to thrive in the present day work place as medical profession subsumes complex contexts; it is in this scenario that, medical educators are entrusted with the challenging task of developing "capable learners". In the heutagogical approach, learners are required to decide upon what to learn and how to learn and therefore the control of the learning process is on the learner and the role of the teacher becomes that of a navigator. This paper highlights the current higher educational practices based on heutagogy, considers its application in the context of Problem-based learning and also discusses a few challenges in incorporating this approach in the existing undergraduate medical curriculum. The article proposes the use of social media in order to support learner autonomy, which in turn improves learners' cognitive engagement with content and tasks, thereby assisting the development of attributes associated with capability.

The Role of Cognition on Navigational Skills of Children and Adolescents With Autism Spectrum Disorders.

PubMed

Robillard, Manon; Roy-Charland, Annie; Cazabon, Sylvie

2018-06-22

This study examined the role of cognition on the navigational process of a speech-generating device (SGD) among individuals with a diagnosis of autism spectrum disorder (ASD). The objective was to investigate the role of various cognitive factors (i.e., cognitive flexibility, sustained attention, categorization, fluid reasoning, and working memory) on the ability to navigate an SGD with dynamic paging and taxonomic grids in individuals with ASD. Twenty individuals aged 5 to 20 years with ASD were assessed using the Leiter International Performance Scale-Revised (Roid & Miller, 1997) and the Automated Working Memory Assessment (Alloway, 2007). They also completed a navigational task using an iPad 4 (Apple, 2017; taxonomic organization). Significant correlations between all of the cognitive factors and the ability to navigate an SGD were revealed. A stepwise linear regression suggested that cognitive flexibility was the best predictor of navigational ability with this population. The importance of cognition in the navigational process of an SGD with dynamic paging in children and adolescents with ASD has been highlighted by the results of this study.

Is All Motivation Good for Learning? Dissociable Influences of Approach and Avoidance Motivation in Declarative Memory

ERIC Educational Resources Information Center

Murty, Vishnu P.; LaBar, Kevin S.; Hamilton, Derek A.; Adcock, R. Alison

2011-01-01

The present study investigated the effects of approach versus avoidance motivation on declarative learning. Human participants navigated a virtual reality version of the Morris water task, a classic spatial memory paradigm, adapted to permit the experimental manipulation of motivation during learning. During this task, participants were instructed…

Differences and Similarities in Information Seeking: Children and Adults as Web Users.

ERIC Educational Resources Information Center

Bilal, Dania; Kirby, Joe

2002-01-01

Analyzed and compared the success and information seeking behaviors of seventh grade science students and graduate students in using the Yahooligans! Web search engine. Discusses cognitive, affective, and physical behaviors during a fact-finding task, including searching, browsing, and time to complete the task; navigational styles; and focus on…

Co-Thought Gestures: Supporting Students to Successfully Navigate Map Tasks

ERIC Educational Resources Information Center

Logan, Tracy; Lowrie, Tom; Diezmann, Carmel M.

2014-01-01

This study considers the role and nature of co-thought gestures when students process map-based mathematics tasks. These gestures are typically spontaneously produced silent gestures which do not accompany speech and are represented by small movements of the hands or arms often directed toward an artefact. The study analysed 43 students (aged…

33 CFR 5.29 - Assignment to duty on a motorboat, yacht, aircraft, or radio station.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., yacht, aircraft, or radio station. 5.29 Section 5.29 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY GENERAL COAST GUARD AUXILIARY § 5.29 Assignment to duty on a motorboat, yacht, aircraft, or radio station. No member of the Auxiliary shall be placed in charge of a motorboat, yacht...

33 CFR 5.29 - Assignment to duty on a motorboat, yacht, aircraft, or radio station.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., yacht, aircraft, or radio station. 5.29 Section 5.29 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY GENERAL COAST GUARD AUXILIARY § 5.29 Assignment to duty on a motorboat, yacht, aircraft, or radio station. No member of the Auxiliary shall be placed in charge of a motorboat, yacht...

33 CFR 334.320 - Chesapeake Bay entrance; naval restricted area.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Chesapeake Bay entrance; naval... entrance; naval restricted area. (a) The area. Beginning at a point on the south shore of Chesapeake Bay at... shall be placed on or near the bottom. (2) This section shall be enforced by the Commandant, Fifth Naval...

33 CFR 334.320 - Chesapeake Bay entrance; naval restricted area.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Chesapeake Bay entrance; naval... entrance; naval restricted area. (a) The area. Beginning at a point on the south shore of Chesapeake Bay at... shall be placed on or near the bottom. (2) This section shall be enforced by the Commandant, Fifth Naval...

33 CFR 84.24 - High-speed craft.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false High-speed craft. 84.24 Section... RULES ANNEX I: POSITIONING AND TECHNICAL DETAILS OF LIGHTS AND SHAPES § 84.24 High-speed craft. (a) The masthead light of high-speed craft with a length to breadth ratio of less than 3.0 may be placed at a...

33 CFR 84.24 - High-speed craft.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false High-speed craft. 84.24 Section... RULES ANNEX I: POSITIONING AND TECHNICAL DETAILS OF LIGHTS AND SHAPES § 84.24 High-speed craft. (a) The masthead light of high-speed craft with a length to breadth ratio of less than 3.0 may be placed at a...

78 FR 39163 - Navigation and Navigable Waters; Technical, Organizational, and Conforming Amendments

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-01

... publication in the Federal Register. III. Background and Purpose Each year, the printed edition of Title 33 of... Mapping Agency changed its name to the National Geospatial- Intelligence Agency. This rule removes the references to printed versions of the LNM in Sec. 72.01-10(c). In place of paragraph (c) is an updated link...

Indoor magnetic navigation for the blind.

PubMed

Riehle, Timothy H; Anderson, Shane M; Lichter, Patrick A; Giudice, Nicholas A; Sheikh, Suneel I; Knuesel, Robert J; Kollmann, Daniel T; Hedin, Daniel S

2012-01-01

Indoor navigation technology is needed to support seamless mobility for the visually impaired. This paper describes the construction of and evaluation of a navigation system that infers the users' location using only magnetic sensing. It is well known that the environments within steel frame structures are subject to significant magnetic distortions. Many of these distortions are persistent and have sufficient strength and spatial characteristics to allow their use as the basis for a location technology. This paper describes the development and evaluation of a prototype magnetic navigation system consisting of a wireless magnetometer placed at the users' hip streaming magnetic readings to a smartphone processing location algorithms. Human trials were conducted to assess the efficacy of the system by studying route-following performance with blind and sighted subjects using the navigation system for real-time guidance.

Differences in navigation performance and postpartal striatal volume associated with pregnancy in humans.

PubMed

Lisofsky, Nina; Wiener, Jan; de Condappa, Olivier; Gallinat, Jürgen; Lindenberger, Ulman; Kühn, Simone

2016-10-01

Pregnancy is accompanied by prolonged exposure to high estrogen levels. Animal studies have shown that estrogen influences navigation strategies and, hence, affects navigation performance. High estrogen levels are related to increased use of hippocampal-based allocentric strategies and decreased use of striatal-based egocentric strategies. In humans, associations between hormonal shifts and navigation strategies are less well studied. This study compared 30 peripartal women (mean age 28years) to an age-matched control group on allocentric versus egocentric navigation performance (measured in the last month of pregnancy) and gray matter volume (measured within two months after delivery). None of the women had a previous pregnancy before study participation. Relative to controls, pregnant women performed less well in the egocentric condition of the navigation task, but not the allocentric condition. A whole-brain group comparison revealed smaller left striatal volume (putamen) in the peripartal women. Across the two groups, left striatal volume was associated with superior egocentric over allocentric performance. Limited by the cross-sectional study design, the findings are a first indication that human pregnancy might be accompanied by structural brain changes in navigation-related neural systems and concomitant changes in navigation strategy. Copyright © 2016 Elsevier Inc. All rights reserved.

Implant alignment in total elbow arthroplasty: conventional vs. navigated techniques

NASA Astrophysics Data System (ADS)

McDonald, Colin P.; Johnson, James A.; King, Graham J. W.; Peters, Terry M.

2009-02-01

Incorrect selection of the native flexion-extension axis during implant alignment in elbow replacement surgery is likely a significant contributor to failure of the prosthesis. Computer and image-assisted surgery is emerging as a useful surgical tool in terms of improving the accuracy of orthopaedic procedures. This study evaluated the accuracy of implant alignment using an image-based navigation technique compared against a conventional non-navigated approach. Implant alignment error was 0.8 +/- 0.3 mm in translation and 1.1 +/- 0.4° in rotation for the navigated alignment, compared with 3.1 +/- 1.3 mm and 5.0 +/- 3.8° for the non-navigated alignment. Five (5) of the 11 non-navigated alignments were malaligned greater than 5° while none of the navigated alignments were placed with an error of greater than 2.0°. It is likely that improved implant positioning will lead to reduced implant loading and wear, resulting in fewer implantrelated complications and revision surgeries.

A Comparison of Sleep and Performance of Sailors on an Operationally Deployed U.S. Navy Warship

DTIC Science & Technology

2013-09-01

The crew’s mission on a deployed warship is inherently dangerous. The nature of the job means navigating restricted waters, conducting underway...The nature of the job means navigating restricted waters, conducting underway replenishments with less than 200 feet of lateral separation from... concentration equivalent. Error bars ± s.e. (From Dawson & Reid, 1997). .............................9 Figure 4. Mean psychomotor vigilance task speed (and

When Do Objects Become Landmarks? A VR Study of the Effect of Task Relevance on Spatial Memory

PubMed Central

Han, Xue; Byrne, Patrick; Kahana, Michael; Becker, Suzanna

2012-01-01

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. PMID:22586455

The impact of crosstalk on three-dimensional laparoscopic performance and workload.

PubMed

Sakata, Shinichiro; Grove, Philip M; Watson, Marcus O; Stevenson, Andrew R L

2017-10-01

This is the first study to explore the effects of crosstalk from 3D laparoscopic displays on technical performance and workload. We studied crosstalk at magnitudes that may have been tolerated during laparoscopic surgery. Participants were 36 voluntary doctors. To minimize floor effects, participants completed their surgery rotations, and a laparoscopic suturing course for surgical trainees. We used a counterbalanced, within-subjects design in which participants were randomly assigned to complete laparoscopic tasks in one of six unique testing sequences. In a simulation laboratory, participants were randomly assigned to complete laparoscopic 'navigation in space' and suturing tasks in three viewing conditions: 2D, 3D without ghosting and 3D with ghosting. Participants calibrated their exposure to crosstalk as the maximum level of ghosting that they could tolerate without discomfort. The Randot® Stereotest was used to verify stereoacuity. The study performance metric was time to completion. The NASA TLX was used to measure workload. Normal threshold stereoacuity (40-20 second of arc) was verified in all participants. Comparing optimal 3D with 2D viewing conditions, mean performance times were 2.8 and 1.6 times faster in laparoscopic navigation in space and suturing tasks respectively (p< .001). Comparing optimal 3D with suboptimal 3D viewing conditions, mean performance times were 2.9 times faster in both tasks (p< .001). Mean workload in 2D was 1.5 and 1.3 times greater than in optimal 3D viewing, for navigation in space and suturing tasks respectively (p< .001). Mean workload associated with suboptimal 3D was 1.3 times greater than optimal 3D in both laparoscopic tasks (p< .001). There was no significant relationship between the magnitude of ghosting score, laparoscopic performance and workload. Our findings highlight the advantages of 3D displays when used optimally, and their shortcomings when used sub-optimally, on both laparoscopic performance and workload.

An evaluation of unisensory and multisensory adaptive flight-path navigation displays

NASA Astrophysics Data System (ADS)

Moroney, Brian W.

1999-11-01

The present study assessed the use of unimodal (auditory or visual) and multimodal (audio-visual) adaptive interfaces to aid military pilots in the performance of a precision-navigation flight task when they were confronted with additional information-processing loads. A standard navigation interface was supplemented by adaptive interfaces consisting of either a head-up display based flight director, a 3D virtual audio interface, or a combination of the two. The adaptive interfaces provided information about how to return to the pathway when off course. Using an advanced flight simulator, pilots attempted two navigation scenarios: (A) maintain proper course under normal flight conditions and (B) return to course after their aircraft's position has been perturbed. Pilots flew in the presence or absence of an additional information-processing task presented in either the visual or auditory modality. The additional information-processing tasks were equated in terms of perceived mental workload as indexed by the NASA-TLX. Twelve experienced military pilots (11 men and 1 woman), naive to the purpose of the experiment, participated in the study. They were recruited from Wright-Patterson Air Force Base and had a mean of 2812 hrs. of flight experience. Four navigational interface configurations, the standard visual navigation interface alone (SV), SV plus adaptive visual, SV plus adaptive auditory, and SV plus adaptive visual-auditory composite were combined factorially with three concurrent tasks (CT), the no CT, the visual CT, and the auditory CT, a completely repeated measures design. The adaptive navigation displays were activated whenever the aircraft was more than 450 ft off course. In the normal flight scenario, the adaptive interfaces did not bolster navigation performance in comparison to the standard interface. It is conceivable that the pilots performed quite adequately using the familiar generic interface under normal flight conditions and hence showed no added benefit of the adaptive interfaces. In the return-to-course scenario, the relative advantages of the three adaptive interfaces were dependent upon the nature of the CT in a complex way. In the absence of a CT, recovery heading performance was superior with the adaptive visual and adaptive composite interfaces compared to the adaptive auditory interface. In the context of a visual CT, recovery when using the adaptive composite interface was superior to that when using the adaptive visual interface. Post-experimental inquiry indicated that when faced with a visual CT, the pilots used the auditory component of the multimodal guidance display to detect gross heading errors and the visual component to make more fine-grained heading adjustments. In the context of the auditory CT, navigation performance using the adaptive visual interface tended to be superior to that when using the adaptive auditory interface. Neither CT performance nor NASA-TLX workload level was influenced differentially by the interface configurations. Thus, the potential benefits associated with the proposed interfaces appear to be unaccompanied by negative side effects involving CT interference and workload. The adaptive interface configurations were altered without any direct input from the pilot. Thus, it was feared that pilots might reject the activation of interfaces independent of their control. However, pilots' debriefing comments about the efficacy of the adaptive interface approach were very positive. (Abstract shortened by UMI.)

Navigational Efficiency of Nocturnal Myrmecia Ants Suffers at Low Light Levels

PubMed Central

Narendra, Ajay; Reid, Samuel F.; Raderschall, Chloé A.

2013-01-01

Insects face the challenge of navigating to specific goals in both bright sun-lit and dim-lit environments. Both diurnal and nocturnal insects use quite similar navigation strategies. This is despite the signal-to-noise ratio of the navigational cues being poor at low light conditions. To better understand the evolution of nocturnal life, we investigated the navigational efficiency of a nocturnal ant, Myrmecia pyriformis, at different light levels. Workers of M. pyriformis leave the nest individually in a narrow light-window in the evening twilight to forage on nest-specific Eucalyptus trees. The majority of foragers return to the nest in the morning twilight, while few attempt to return to the nest throughout the night. We found that as light levels dropped, ants paused for longer, walked more slowly, the success in finding the nest reduced and their paths became less straight. We found that in both bright and dark conditions ants relied predominantly on visual landmark information for navigation and that landmark guidance became less reliable at low light conditions. It is perhaps due to the poor navigational efficiency at low light levels that the majority of foragers restrict navigational tasks to the twilight periods, where sufficient navigational information is still available. PMID:23484052

Operation and Maintenance, 9-Foot Navigation Channel, Upper Mississippi River, Head of Navigation to Guttenberg, Iowa. Volume 2. Exhibits.

DTIC Science & Technology

1974-08-01

employ methods which differ from those employed by them in the past. This action was commenced on June 19, 1973. There followed certain proceedings in...Sedimentation in Navigation Pools - Trap Efficiency Method 66 67 Textures of Samples from Pools 4, 5, 5A,and 6 67 68- Textures of Samples from Tributary...island and surrounding waters located in the Mississippi River as aforesaid. 15. The method of disposal is such that the spoil material is placed on

Navigation: traveling the water highways!

USGS Publications Warehouse

Fisher, Marion; Vandas, Stephen; Farrar, Frank

1996-01-01

NAVIGATION is travel or transportation over water. Many different kinds of boats and ships are used on rivers and oceans to move people and products from one place to another. Navigation was extremely important for foreign and domestic trade and travel in the early days of our country before cars, trucks, trains, and airplanes were invented. In those days, rivers were used as "roads" to connect inland settlements to river and coastal ports. Communities established at these commercial ports became important economic, cultural, and social hubs in the development of our Nation.

Mobile Robot Designed with Autonomous Navigation System

NASA Astrophysics Data System (ADS)

An, Feng; Chen, Qiang; Zha, Yanfang; Tao, Wenyin

2017-10-01

With the rapid development of robot technology, robots appear more and more in all aspects of life and social production, people also ask more requirements for the robot, one is that robot capable of autonomous navigation, can recognize the road. Take the common household sweeping robot as an example, which could avoid obstacles, clean the ground and automatically find the charging place; Another example is AGV tracking car, which can following the route and reach the destination successfully. This paper introduces a new type of robot navigation scheme: SLAM, which can build the environment map in a totally strange environment, and at the same time, locate its own position, so as to achieve autonomous navigation function.

Cholinergic modulation of the CAN current may adjust neural dynamics for active memory maintenance, spatial navigation and time-compressed replay

PubMed Central

Yoshida, Motoharu; Knauer, Beate; Jochems, Arthur

2012-01-01

Suppression of cholinergic receptors and inactivation of the septum impair short-term memory, and disrupt place cell and grid cell activity in the medial temporal lobe (MTL). Location-dependent hippocampal place cell firing during active waking, when the acetylcholine level is high, switches to time-compressed replay activity during quiet waking and slow-wave-sleep (SWS), when the acetylcholine level is low. However, it remains largely unknown how acetylcholine supports short-term memory, spatial navigation, and the functional switch to replay mode in the MTL. In this paper, we focus on the role of the calcium-activated non-specific cationic (CAN) current which is activated by acetylcholine. The CAN current is known to underlie persistent firing, which could serve as a memory trace in many neurons in the MTL. Here, we review the CAN current and discuss possible roles of the CAN current in short-term memory and spatial navigation. We further propose a novel theoretical model where the CAN current switches the hippocampal place cell activity between real-time and time-compressed sequential activity during encoding and consolidation, respectively. PMID:22435051

[Clinical application of accurate placement of lumbar pedicle screws using three-dimensional printing navigational templates under Quadrant system].

PubMed

Chen, Xuanhuang; Yu, Zhengxi; Wu, Changfu; Li, Xing; Chen, Xu; Zhang, Guodong; Zheng, Zugao; Lin, Haibin

2017-02-01

To explore the feasibility and the effectiveness of the accurate placement of lumbar pedicle screws using three-dimensional (3D) printing navigational templates in Quadrant minimally invasive system. The L 1-5 spines of 12 adult cadavers were scanned using CT. The 3D models of the lumbar spines were established. The screw trajectory was designed to pass through the central axis of the pedicle by using Mimics software. The navigational template was designed and 3D-printed according to the bony surface where the soft tissues could be removed. The placed screws were scanned using CT to create the 3D model again after operation. The 3D models of the designed trajectory and the placed screws were registered to evaluate the placed screws coincidence rate. Between November 2014 and November 2015, 31 patients with lumbar instability accepted surgery assisted with 3D-printing navigation module under Quadrant minimally invasive system. There were 14 males and 17 females, aged from 42 to 60 years, with an average of 45.2 years. The disease duration was 6-13 months (mean, 8.8 months). Single segment was involved in 15 cases, two segments in 13 cases, and three segments in 3 cases. Preoperative visual analogue scale (VAS) was 7.59±1.04; Oswestry disability index (ODI) was 76.21±5.82; and the Japanese Orthopaedic Association (JOA) score was 9.21±1.64. A total of 120 screws were placed in 12 cadavers specimens. The coincidence rate of placed screw was 100%. A total of 162 screws were implanted in 31 patients. The operation time was 65-147 minutes (mean, 102.23 minutes); the intraoperative blood loss was 50-116 mL (mean, 78.20 mL); and the intraoperative radiation exposure time was 8-54 seconds (mean, 42 seconds). At 3-7 days after operation, CT showed that the coincidence rate of the placed screws was 98.15% (159/162). At 4 weeks after operation, VAS, ODI, and JOA score were 2.24±0.80, 29.17±2.50, and 23.43±1.14 respectively, showing significant differences when compared with preoperative ones ( t =14.842, P =0.006; t =36.927, P =0.002; t =-36.031, P =0.001). Thirty-one patients were followed up 8-24 months (mean, 18.7 months). All incision healed by first intention, and no complication occurred. During the follow-up, X-ray film and CT showed that pedicle screw was accurately placed without loosening or breakage, and with good fusion of intervertebral bone graft. 3D-printing navigational templates in Quadrant minimally invasive system can help lumbar surgery gain minimal invasion, less radiation, and accurate placement.

Does order matter? Investigating the effect of sequence on glance duration during on-road driving

PubMed Central

Roberts, Shannon C.; Reimer, Bryan; Mehler, Bruce

2017-01-01

Previous literature has shown that vehicle crash risks increases as drivers’ off-road glance duration increases. Many factors influence drivers’ glance duration such as individual differences, driving environment, or task characteristics. Theories and past studies suggest that glance duration increases as the task progresses, but the exact relationship between glance sequence and glance durations is not fully understood. The purpose of this study was to examine the effect of glance sequence on glance duration among drivers completing a visual-manual radio tuning task and an auditory-vocal based multi-modal navigation entry task. Eighty participants drove a vehicle on urban highways while completing radio tuning and navigation entry tasks. Forty participants drove under an experimental protocol that required three button presses followed by rotation of a tuning knob to complete the radio tuning task while the other forty participants completed the task with one less button press. Multiple statistical analyses were conducted to measure the effect of glance sequence on glance duration. Results showed that across both tasks and a variety of statistical tests, glance sequence had inconsistent effects on glance duration—the effects varied according to the number of glances, task type, and data set that was being evaluated. Results suggest that other aspects of the task as well as interface design effect glance duration and should be considered in the context of examining driver attention or lack thereof. All in all, interface design and task characteristics have a more influential impact on glance duration than glance sequence, suggesting that classical design considerations impacting driver attention, such as the size and location of buttons, remain fundamental in designing in-vehicle interfaces. PMID:28158301

A Mobile App (BEDSide Mobility) to Support Nurses’ Tasks at the Patient's Bedside: Usability Study

PubMed Central

Weinhold, Thomas; Joe, Jonathan; Lovis, Christian; Blondon, Katherine

2018-01-01

Background The introduction of clinical information systems has increased the amount of clinical documentation. Although this documentation generally improves patient safety, it has become a time-consuming task for nurses, which limits their time with the patient. On the basis of a user-centered methodology, we have developed a mobile app named BEDSide Mobility to support nurses in their daily workflow and to facilitate documentation at the bedside. Objective The aim of the study was to assess the usability of the BEDSide Mobility app in terms of the navigation and interaction design through usability testing. Methods Nurses were asked to complete a scenario reflecting their daily work with patients. Their interactions with the app were captured with eye-tracking glasses and by using the think aloud protocol. After completing the tasks, participants filled out the system usability scale questionnaire. Descriptive statistics were used to summarize task completion rates and the users’ performance. Results A total of 10 nurses (aged 21-50) participated in the study. Overall, they were satisfied with the navigation, layout, and interaction design of the app, with the exception of one user who was unfamiliar with smartphones. The problems identified were related to the ambiguity of some icons, the navigation logic, and design inconsistency. Conclusions Besides the usability issues identified in the app, the participants’ results do indicate good usability, high acceptance, and high satisfaction with the developed app. However, the results must be taken with caution because of the poor ecological validity of the experimental setting. PMID:29563074

The Aging Navigational System.

PubMed

Lester, Adam W; Moffat, Scott D; Wiener, Jan M; Barnes, Carol A; Wolbers, Thomas

2017-08-30

The discovery of neuronal systems dedicated to computing spatial information, composed of functionally distinct cell types such as place and grid cells, combined with an extensive body of human-based behavioral and neuroimaging research has provided us with a detailed understanding of the brain's navigation circuit. In this review, we discuss emerging evidence from rodents, non-human primates, and humans that demonstrates how cognitive aging affects the navigational computations supported by these systems. Critically, we show 1) that navigational deficits cannot solely be explained by general deficits in learning and memory, 2) that there is no uniform decline across different navigational computations, and 3) that navigational deficits might be sensitive markers for impending pathological decline. Following an introduction to the mechanisms underlying spatial navigation and how they relate to general processes of learning and memory, the review discusses how aging affects the perception and integration of spatial information, the creation and storage of memory traces for spatial information, and the use of spatial information during navigational behavior. The closing section highlights the clinical potential of behavioral and neural markers of spatial navigation, with a particular emphasis on neurodegenerative disorders. Copyright © 2017 Elsevier Inc. All rights reserved.

Maintenance Operations of the Federal Navigation Channels and Structures at Bolles Harbor, Michigan.

DTIC Science & Technology

1978-02-01

uncontaminated portion of the navigation channel would be placed at the 2600’ x 2600’ open water disposal site located in Lake Erie, approximately 4 1/4...4.38 Commercial Fishing ........................ 25 4.39 Archaeological and Historical Sites ....... 25 4.40 Threatened or Endangered Species...53 ATTACHMENTS Bolles Harbor, Michigan, Project ap ............... *....... 55 Proposed Disposal Sites

Brenna's Story: A Critical Reflection and Analysis of One Mother's Experience of Navigating the Medical System with a Child with Intellectual Disabilities

ERIC Educational Resources Information Center

Bye, Amanda; Aston, Megan

2016-01-01

Children with intellectual disabilities spend more time in the health-care system than mainstream children. Parents have to learn how to navigate the system by coordinating appointments, understanding the referral process, knowing what services are available, and advocating for those services. This places an incredible amount of responsibility on…

The Black Kitchen Table Agreement: The Power of Silence during The Era of Trump

ERIC Educational Resources Information Center

Williams, Nathaniel Andrew

2017-01-01

The Black kitchen table has long served as a meeting place for Black families to discuss, debate, and critique issues related to the Black struggle. In particular, it was common for Black kitchen table conversations to talk about the nuances of navigating systems of legalized segregation and oppression, as well--and more recently--navigating the…

U.S. Army Medical Department Journal, October-December 2007

DTIC Science & Technology

2007-12-01

Warrior Task Training requirements (such as weapons assembly/disassembly and functions check; individual chemical, biological , radiological, nuclear...training program focused on hands-on training in the 40 Army Warrior Tasks and 11 Battle Drills, to include advanced land navigation training; weapons ...familiarization and qualification; convoy operations; chemical, biological , radiological, nuclear and high- explosive defense; and squad and platoon

Hippocampus and Retrosplenial Cortex Combine Path Integration Signals for Successful Navigation

PubMed Central

Erdem, Uğur M.; Ross, Robert S.; Brown, Thackery I.; Hasselmo, Michael E.; Stern, Chantal E.

2013-01-01

The current study used fMRI in humans to examine goal-directed navigation in an open field environment. We designed a task that required participants to encode survey-level spatial information and subsequently navigate to a goal location in either first person, third person, or survey perspectives. Critically, no distinguishing landmarks or goal location markers were present in the environment, thereby requiring participants to rely on path integration mechanisms for successful navigation. We focused our analysis on mechanisms related to navigation and mechanisms tracking linear distance to the goal location. Successful navigation required translation of encoded survey-level map information for orientation and implementation of a planned route to the goal. Our results demonstrate that successful first and third person navigation trials recruited the anterior hippocampus more than trials when the goal location was not successfully reached. When examining only successful trials, the retrosplenial and posterior parietal cortices were recruited for goal-directed navigation in both first person and third person perspectives. Unique to first person perspective navigation, the hippocampus was recruited to path integrate self-motion cues with location computations toward the goal location. Last, our results demonstrate that the hippocampus supports goal-directed navigation by actively tracking proximity to the goal throughout navigation. When using path integration mechanisms in first person and third person perspective navigation, the posterior hippocampus was more strongly recruited as participants approach the goal. These findings provide critical insight into the neural mechanisms by which we are able to use map-level representations of our environment to reach our navigational goals. PMID:24305826

Kinematic evaluation of virtual walking trajectories.

PubMed

Cirio, Gabriel; Olivier, Anne-Hélène; Marchal, Maud; Pettré, Julien

2013-04-01

Virtual walking, a fundamental task in Virtual Reality (VR), is greatly influenced by the locomotion interface being used, by the specificities of input and output devices, and by the way the virtual environment is represented. No matter how virtual walking is controlled, the generation of realistic virtual trajectories is absolutely required for some applications, especially those dedicated to the study of walking behaviors in VR, navigation through virtual places for architecture, rehabilitation and training. Previous studies focused on evaluating the realism of locomotion trajectories have mostly considered the result of the locomotion task (efficiency, accuracy) and its subjective perception (presence, cybersickness). Few focused on the locomotion trajectory itself, but in situation of geometrically constrained task. In this paper, we study the realism of unconstrained trajectories produced during virtual walking by addressing the following question: did the user reach his destination by virtually walking along a trajectory he would have followed in similar real conditions? To this end, we propose a comprehensive evaluation framework consisting on a set of trajectographical criteria and a locomotion model to generate reference trajectories. We consider a simple locomotion task where users walk between two oriented points in space. The travel path is analyzed both geometrically and temporally in comparison to simulated reference trajectories. In addition, we demonstrate the framework over a user study which considered an initial set of common and frequent virtual walking conditions, namely different input devices, output display devices, control laws, and visualization modalities. The study provides insight into the relative contributions of each condition to the overall realism of the resulting virtual trajectories.

SRA (Short Range Aids to Navigation) Resource Management: Measures of Effectiveness.

DTIC Science & Technology

1986-09-01

invest ’ ’-" in R&D and technological innovation. uit Measures of effectiveness developed under the first task deal primarily with safety...illustratve example presented in Chapter 5. A project of this nature and complexity could not be carried out without the assistance and support of others. A...helping the project attain its goals. Foremost is Mr. Karl R. Schroeder, Short Range Aids to Navigation Section Chief in the USCG

Multiple paths in complex tasks

NASA Technical Reports Server (NTRS)

Galanter, Eugene; Wiegand, Thomas; Mark, Gloria

1987-01-01

The relationship between utility judgments of subtask paths and the utility of the task as a whole was examined. The convergent validation procedure is based on the assumption that measurements of the same quantity done with different methods should covary. The utility measures of the subtasks were obtained during the performance of an aircraft flight controller navigation task. Analyses helped decide among various models of subtask utility combination, whether the utility ratings of subtask paths predict the whole tasks utility rating, and indirectly, whether judgmental models need to include the equivalent of cognitive noise.

Oncology Nurse Navigation: Results of the 2016 Role Delineation Study.

PubMed

Lubejko, Barbara G; Bellfield, Sonia; Kahn, Elisa; Lee, Carrie; Peterson, Nicole; Rose, Traudi; Murphy, Cynthia Miller; McCorkle, Michele

2017-02-01

In 2011, an oncology nurse navigator (ONN) role delineation survey (RDS) was conducted by the Oncology Nursing Society (ONS) when the role was relatively new to oncology. Results did not demonstrate a unique skill set for the ONN; however, since then, the role has expanded. ONS and the Oncology Nursing Certification Corporation partnered in 2016 to complete an RDS of ONNs to redefine the role and determine the need for an ONN certification examination. A structured RDS was conducted using a formal consensus-building process. A survey was developed and released to examine the specific tasks, knowledge, and skills for the ONN as well as to determine which role possesses more responsibility for the tasks. The ONN role is evolving, and more was learned about its key tasks, including differences in the responsibilities of the ONN and the clinical or staff nurse. However, the RDS did not find an adequate difference in the knowledge required by the ONN and the clinical or staff nurse to support the need for a separate ONN certification.

Egnos Limitations over Central and Eastern Poland - Results of Preliminary Tests of Egnos-Eupos Integration Project

NASA Astrophysics Data System (ADS)

Jaworski, Leszek; Swiatek, Anna; Zdunek, Ryszard

2013-09-01

The problem of insufficient accuracy of EGNOS correction for the territory of Poland, located at the edge of EGNOS range is well known. The EEI PECS project (EGNOS EUPOS Integration) assumes improving the EGNOS correction by using the GPS observations from Polish ASG-EUPOS stations. One of the EEI project tasks was the identification of EGNOS performance limitations over Poland and services for EGNOSS-EUPOS combination. The two sets of data were used for those goals: statistical, theoretical data obtained using the SBAS simulator software, real data obtained during the measurements. The real measurements were managed as two types of measurements: static and dynamic. Static measurements are continuously managing using Septentrio PolaRx2 receiver. The SRC permanent station works in IMAGE/PERFECT project. Dynamic measurements were managed using the Mobile GPS Laboratory (MGL). Receivers (geodetic and navigation) were working in two modes: determining navigation position from standalone GPS, determining navigation position from GPS plus EGNOS correction. The paper presents results of measurements' analyses and conclusions based on which the next tasks in EEI project are completed

Autonomous Wheeled Robot Platform Testbed for Navigation and Mapping Using Low-Cost Sensors

NASA Astrophysics Data System (ADS)

Calero, D.; Fernandez, E.; Parés, M. E.

2017-11-01

This paper presents the concept of an architecture for a wheeled robot system that helps researchers in the field of geomatics to speed up their daily research on kinematic geodesy, indoor navigation and indoor positioning fields. The presented ideas corresponds to an extensible and modular hardware and software system aimed at the development of new low-cost mapping algorithms as well as at the evaluation of the performance of sensors. The concept, already implemented in the CTTC's system ARAS (Autonomous Rover for Automatic Surveying) is generic and extensible. This means that it is possible to incorporate new navigation algorithms or sensors at no maintenance cost. Only the effort related to the development tasks required to either create such algorithms needs to be taken into account. As a consequence, change poses a much small problem for research activities in this specific area. This system includes several standalone sensors that may be combined in different ways to accomplish several goals; that is, this system may be used to perform a variety of tasks, as, for instance evaluates positioning algorithms performance or mapping algorithms performance.

An Assessment of Response, Direction and Place Learning by Rats in a Water T-Maze

ERIC Educational Resources Information Center

Whyte, Jacqueline T.; Martin, Gerard M.; Skinner, Darlene M.

2009-01-01

Behavioral data suggest that distinguishable orientations may be necessary for place learning even when distal cues define different start points in the room and a unique goal location. We examined whether changes in orientation are also important in place learning and navigation in a water T-maze. In Experiment 1, rats were trained to locate a…

Control-display mapping in brain-computer interfaces.

PubMed

Thurlings, Marieke E; van Erp, Jan B F; Brouwer, Anne-Marie; Blankertz, Benjamin; Werkhoven, Peter

2012-01-01

Event-related potential (ERP) based brain-computer interfaces (BCIs) employ differences in brain responses to attended and ignored stimuli. When using a tactile ERP-BCI for navigation, mapping is required between navigation directions on a visual display and unambiguously corresponding tactile stimuli (tactors) from a tactile control device: control-display mapping (CDM). We investigated the effect of congruent (both display and control horizontal or both vertical) and incongruent (vertical display, horizontal control) CDMs on task performance, the ERP and potential BCI performance. Ten participants attended to a target (determined via CDM), in a stream of sequentially vibrating tactors. We show that congruent CDM yields best task performance, enhanced the P300 and results in increased estimated BCI performance. This suggests a reduced availability of attentional resources when operating an ERP-BCI with incongruent CDM. Additionally, we found an enhanced N2 for incongruent CDM, which indicates a conflict between visual display and tactile control orientations. Incongruency in control-display mapping reduces task performance. In this study, brain responses, task and system performance are related to (in)congruent mapping of command options and the corresponding stimuli in a brain-computer interface (BCI). Directional congruency reduces task errors, increases available attentional resources, improves BCI performance and thus facilitates human-computer interaction.

Learning to Predict Consequences as a Method of Knowledge Transfer in Reinforcement Learning.

PubMed

Chalmers, Eric; Contreras, Edgar Bermudez; Robertson, Brandon; Luczak, Artur; Gruber, Aaron

2017-04-17

The reinforcement learning (RL) paradigm allows agents to solve tasks through trial-and-error learning. To be capable of efficient, long-term learning, RL agents should be able to apply knowledge gained in the past to new tasks they may encounter in the future. The ability to predict actions' consequences may facilitate such knowledge transfer. We consider here domains where an RL agent has access to two kinds of information: agent-centric information with constant semantics across tasks, and environment-centric information, which is necessary to solve the task, but with semantics that differ between tasks. For example, in robot navigation, environment-centric information may include the robot's geographic location, while agent-centric information may include sensor readings of various nearby obstacles. We propose that these situations provide an opportunity for a very natural style of knowledge transfer, in which the agent learns to predict actions' environmental consequences using agent-centric information. These predictions contain important information about the affordances and dangers present in a novel environment, and can effectively transfer knowledge from agent-centric to environment-centric learning systems. Using several example problems including spatial navigation and network routing, we show that our knowledge transfer approach can allow faster and lower cost learning than existing alternatives.

Route selection by rats and humans in a navigational traveling salesman problem.

PubMed

Blaser, Rachel E; Ginchansky, Rachel R

2012-03-01

Spatial cognition is typically examined in non-human animals from the perspective of learning and memory. For this reason, spatial tasks are often constrained by the time necessary for training or the capacity of the animal's short-term memory. A spatial task with limited learning and memory demands could allow for more efficient study of some aspects of spatial cognition. The traveling salesman problem (TSP), used to study human visuospatial problem solving, is a simple task with modifiable learning and memory requirements. In the current study, humans and rats were characterized in a navigational version of the TSP. Subjects visited each of 10 baited targets in any sequence from a set starting location. Unlike similar experiments, the roles of learning and memory were purposely minimized; all targets were perceptually available, no distracters were used, and each configuration was tested only once. The task yielded a variety of behavioral measures, including target revisits and omissions, route length, and frequency of transitions between each pair of targets. Both humans and rats consistently chose routes that were more efficient than chance, but less efficient than optimal, and generally less efficient than routes produced by the nearest-neighbor strategy. We conclude that the TSP is a useful and flexible task for the study of spatial cognition in human and non-human animals.

Real-time tracking and virtual endoscopy in cone-beam CT-guided surgery of the sinuses and skull base in a cadaver model.

PubMed

Prisman, Eitan; Daly, Michael J; Chan, Harley; Siewerdsen, Jeffrey H; Vescan, Allan; Irish, Jonathan C

2011-01-01

Custom software was developed to integrate intraoperative cone-beam computed tomography (CBCT) images with endoscopic video for surgical navigation and guidance. A cadaveric head was used to assess the accuracy and potential clinical utility of the following functionality: (1) real-time tracking of the endoscope in intraoperative 3-dimensional (3D) CBCT; (2) projecting an orthogonal reconstructed CBCT image, at or beyond the endoscope, which is parallel to the tip of the endoscope corresponding to the surgical plane; (3) virtual reality fusion of endoscopic video and 3D CBCT surface rendering; and (4) overlay of preoperatively defined contours of anatomical structures of interest. Anatomical landmarks were contoured in CBCT of a cadaveric head. An experienced endoscopic surgeon was oriented to the software and asked to rate the utility of the navigation software in carrying out predefined surgical tasks. Utility was evaluated using a rating scale for: (1) safely completing the task; and (2) potential for surgical training. Surgical tasks included: (1) uncinectomy; (2) ethmoidectomy; (3) sphenoidectomy/pituitary resection; and (4) clival resection. CBCT images were updated following each ablative task. As a teaching tool, the software was evaluated as "very useful" for all surgical tasks. Regarding safety and task completion, the software was evaluated as "no advantage" for task (1), "minimal" for task (2), and "very useful" for tasks (3) and (4). Landmark identification for structures behind bone was "very useful" for both categories. The software increased surgical confidence in safely completing challenging ablative tasks by presenting real-time image guidance for highly complex ablative procedures. In addition, such technology offers a valuable teaching aid to surgeons in training. Copyright © 2011 American Rhinologic Society-American Academy of Otolaryngic Allergy, LLC.

A Novel Augmented Reality Navigation System for Endoscopic Sinus and Skull Base Surgery: A Feasibility Study

PubMed Central

Li, Liang; Yang, Jian; Chu, Yakui; Wu, Wenbo; Xue, Jin; Liang, Ping; Chen, Lei

2016-01-01

Objective To verify the reliability and clinical feasibility of a self-developed navigation system based on an augmented reality technique for endoscopic sinus and skull base surgery. Materials and Methods In this study we performed a head phantom and cadaver experiment to determine the display effect and accuracy of our navigational system. We compared cadaver head-based simulated operations, the target registration error, operation time, and National Aeronautics and Space Administration Task Load Index scores of our navigation system to conventional navigation systems. Results The navigation system developed in this study has a novel display mode capable of fusing endoscopic images to three-dimensional (3-D) virtual images. In the cadaver head experiment, the target registration error was 1.28 ± 0.45 mm, which met the accepted standards of a navigation system used for nasal endoscopic surgery. Compared with conventional navigation systems, the new system was more effective in terms of operation time and the mental workload of surgeons, which is especially important for less experienced surgeons. Conclusion The self-developed augmented reality navigation system for endoscopic sinus and skull base surgery appears to have advantages that outweigh those of conventional navigation systems. We conclude that this navigational system will provide rhinologists with more intuitive and more detailed imaging information, thus reducing the judgment time and mental workload of surgeons when performing complex sinus and skull base surgeries. Ultimately, this new navigational system has potential to increase the quality of surgeries. In addition, the augmented reality navigational system could be of interest to junior doctors being trained in endoscopic techniques because it could speed up their learning. However, it should be noted that the navigation system serves as an adjunct to a surgeon’s skills and knowledge, not as a substitute. PMID:26757365

A Novel Augmented Reality Navigation System for Endoscopic Sinus and Skull Base Surgery: A Feasibility Study.

PubMed

Li, Liang; Yang, Jian; Chu, Yakui; Wu, Wenbo; Xue, Jin; Liang, Ping; Chen, Lei

2016-01-01

To verify the reliability and clinical feasibility of a self-developed navigation system based on an augmented reality technique for endoscopic sinus and skull base surgery. In this study we performed a head phantom and cadaver experiment to determine the display effect and accuracy of our navigational system. We compared cadaver head-based simulated operations, the target registration error, operation time, and National Aeronautics and Space Administration Task Load Index scores of our navigation system to conventional navigation systems. The navigation system developed in this study has a novel display mode capable of fusing endoscopic images to three-dimensional (3-D) virtual images. In the cadaver head experiment, the target registration error was 1.28 ± 0.45 mm, which met the accepted standards of a navigation system used for nasal endoscopic surgery. Compared with conventional navigation systems, the new system was more effective in terms of operation time and the mental workload of surgeons, which is especially important for less experienced surgeons. The self-developed augmented reality navigation system for endoscopic sinus and skull base surgery appears to have advantages that outweigh those of conventional navigation systems. We conclude that this navigational system will provide rhinologists with more intuitive and more detailed imaging information, thus reducing the judgment time and mental workload of surgeons when performing complex sinus and skull base surgeries. Ultimately, this new navigational system has potential to increase the quality of surgeries. In addition, the augmented reality navigational system could be of interest to junior doctors being trained in endoscopic techniques because it could speed up their learning. However, it should be noted that the navigation system serves as an adjunct to a surgeon's skills and knowledge, not as a substitute.

Is all motivation good for learning? Dissociable influences of approach and avoidance motivation in declarative memory.

PubMed

Murty, Vishnu P; LaBar, Kevin S; Hamilton, Derek A; Adcock, R Alison

2011-01-01

The present study investigated the effects of approach versus avoidance motivation on declarative learning. Human participants navigated a virtual reality version of the Morris water task, a classic spatial memory paradigm, adapted to permit the experimental manipulation of motivation during learning. During this task, participants were instructed to navigate to correct platforms while avoiding incorrect platforms. To manipulate motivational states participants were either rewarded for navigating to correct locations (approach) or punished for navigating to incorrect platforms (avoidance). Participants' skin conductance levels (SCLs) were recorded during navigation to investigate the role of physiological arousal in motivated learning. Behavioral results revealed that, overall, approach motivation enhanced and avoidance motivation impaired memory performance compared to nonmotivated spatial learning. This advantage was evident across several performance indices, including accuracy, learning rate, path length, and proximity to platform locations during probe trials. SCL analysis revealed three key findings. First, within subjects, arousal interacted with approach motivation, such that high arousal on a given trial was associated with performance deficits. In addition, across subjects, high arousal negated or reversed the benefits of approach motivation. Finally, low-performing, highly aroused participants showed SCL responses similar to those of avoidance-motivation participants, suggesting that for these individuals, opportunities for reward may evoke states of learning similar to those typically evoked by threats of punishment. These results provide a novel characterization of how approach and avoidance motivation influence declarative memory and indicate a critical and selective role for arousal in determining how reinforcement influences goal-oriented learning.

Is all motivation good for learning? Dissociable influences of approach and avoidance motivation in declarative memory

PubMed Central

Murty, Vishnu P.; LaBar, Kevin S.; Hamilton, Derek A.; Adcock, R. Alison

2011-01-01

The present study investigated the effects of approach versus avoidance motivation on declarative learning. Human participants navigated a virtual reality version of the Morris water task, a classic spatial memory paradigm, adapted to permit the experimental manipulation of motivation during learning. During this task, participants were instructed to navigate to correct platforms while avoiding incorrect platforms. To manipulate motivational states participants were either rewarded for navigating to correct locations (approach) or punished for navigating to incorrect platforms (avoidance). Participants’ skin conductance levels (SCLs) were recorded during navigation to investigate the role of physiological arousal in motivated learning. Behavioral results revealed that, overall, approach motivation enhanced and avoidance motivation impaired memory performance compared to nonmotivated spatial learning. This advantage was evident across several performance indices, including accuracy, learning rate, path length, and proximity to platform locations during probe trials. SCL analysis revealed three key findings. First, within subjects, arousal interacted with approach motivation, such that high arousal on a given trial was associated with performance deficits. In addition, across subjects, high arousal negated or reversed the benefits of approach motivation. Finally, low-performing, highly aroused participants showed SCL responses similar to those of avoidance–motivation participants, suggesting that for these individuals, opportunities for reward may evoke states of learning similar to those typically evoked by threats of punishment. These results provide a novel characterization of how approach and avoidance motivation influence declarative memory and indicate a critical and selective role for arousal in determining how reinforcement influences goal-oriented learning. PMID:22021253

Cultural background shapes spatial reference frame proclivity

PubMed Central

Goeke, Caspar; Kornpetpanee, Suchada; Köster, Moritz; Fernández-Revelles, Andrés B.; Gramann, Klaus; König, Peter

2015-01-01

Spatial navigation is an essential human skill that is influenced by several factors. The present study investigates how gender, age, and cultural background account for differences in reference frame proclivity and performance in a virtual navigation task. Using an online navigation study, we recorded reaction times, error rates (confusion of turning axis), and reference frame proclivity (egocentric vs. allocentric reference frame) of 1823 participants. Reaction times significantly varied with gender and age, but were only marginally influenced by the cultural background of participants. Error rates were in line with these results and exhibited a significant influence of gender and culture, but not age. Participants’ cultural background significantly influenced reference frame selection; the majority of North-Americans preferred an allocentric strategy, while Latin-Americans preferred an egocentric navigation strategy. European and Asian groups were in between these two extremes. Neither the factor of age nor the factor of gender had a direct impact on participants’ navigation strategies. The strong effects of cultural background on navigation strategies without the influence of gender or age underlines the importance of socialized spatial cognitive processes and argues for socio-economic analysis in studies investigating human navigation. PMID:26073656

The place-value of a digit in multi-digit numbers is processed automatically.

PubMed

Kallai, Arava Y; Tzelgov, Joseph

2012-09-01

The automatic processing of the place-value of digits in a multi-digit number was investigated in 4 experiments. Experiment 1 and two control experiments employed a numerical comparison task in which the place-value of a non-zero digit was varied in a string composed of zeros. Experiment 2 employed a physical comparison task in which strings of digits varied in their physical sizes. In both types of tasks, the place-value of the non-zero digit in the string was irrelevant to the task performed. Interference of the place-value information was found in both tasks. When the non-zero digit occupied a lower place-value, it was recognized slower as a larger digit or as written in a larger font size. We concluded that place-value in a multi-digit number is processed automatically. These results support the notion of a decomposed representation of multi-digit numbers in memory. PsycINFO Database Record (c) 2012 APA, all rights reserved.

Control of free-flying space robot manipulator systems

NASA Technical Reports Server (NTRS)

Cannon, Robert H., Jr.

1989-01-01

Control techniques for self-contained, autonomous free-flying space robots are being tested and developed. Free-flying space robots are envisioned as a key element of any successful long term presence in space. These robots must be capable of performing the assembly, maintenance, and inspection, and repair tasks that currently require astronaut extra-vehicular activity (EVA). Use of robots will provide economic savings as well as improved astronaut safety by reducing and in many cases, eliminating the need for human EVA. The focus of the work is to develop and carry out a set of research projects using laboratory models of satellite robots. These devices use air-cushion-vehicle (ACV) technology to simulate in two dimensions the drag-free, zero-g conditions of space. Current work is divided into six major projects or research areas. Fixed-base cooperative manipulation work represents our initial entry into multiple arm cooperation and high-level control with a sophisticated user interface. The floating-base cooperative manipulation project strives to transfer some of the technologies developed in the fixed-base work onto a floating base. The global control and navigation experiment seeks to demonstrate simultaneous control of the robot manipulators and the robot base position so that tasks can be accomplished while the base is undergoing a controlled motion. The multiple-vehicle cooperation project's goal is to demonstrate multiple free-floating robots working in teams to carry out tasks too difficult or complex for a single robot to perform. The Location Enhancement Arm Push-off (LEAP) activity's goal is to provide a viable alternative to expendable gas thrusters for vehicle propulsion wherein the robot uses its manipulators to throw itself from place to place. Because the successful execution of the LEAP technique requires an accurate model of the robot and payload mass properties, it was deemed an attractive testbed for adaptive control technology.

Research on navigation of satellite constellation based on an asynchronous observation model using X-ray pulsar

NASA Astrophysics Data System (ADS)

Guo, Pengbin; Sun, Jian; Hu, Shuling; Xue, Ju

2018-02-01

Pulsar navigation is a promising navigation method for high-altitude orbit space tasks or deep space exploration. At present, an important reason for restricting the development of pulsar navigation is that navigation accuracy is not high due to the slow update of the measurements. In order to improve the accuracy of pulsar navigation, an asynchronous observation model which can improve the update rate of the measurements is proposed on the basis of satellite constellation which has a broad space for development because of its visibility and reliability. The simulation results show that the asynchronous observation model improves the positioning accuracy by 31.48% and velocity accuracy by 24.75% than that of the synchronous observation model. With the new Doppler effects compensation method in the asynchronous observation model proposed in this paper, the positioning accuracy is improved by 32.27%, and the velocity accuracy is improved by 34.07% than that of the traditional method. The simulation results show that without considering the clock error will result in a filtering divergence.

Desktop-VR system for preflight 3D navigation training

NASA Astrophysics Data System (ADS)

Aoki, Hirofumi; Oman, Charles M.; Buckland, Daniel A.; Natapoff, Alan

Crews who inhabit spacecraft with complex 3D architecture frequently report inflight disorientation and navigation problems. Preflight virtual reality (VR) training may reduce those risks. Although immersive VR techniques may better support spatial orientation training in a local environment, a non-immersive desktop (DT) system may be more convenient for navigation training in "building scale" spaces, especially if the two methods achieve comparable results. In this study trainees' orientation and navigation performance during simulated space station emergency egress tasks was compared while using immersive head-mounted display (HMD) and DT-VR systems. Analyses showed no differences in pointing angular-error or egress time among the groups. The HMD group was significantly faster than DT group when pointing from destination to start location and from start toward different destination. However, this may be attributed to differences in the input device used (a head-tracker for HMD group vs. a keyboard touchpad or a gamepad in the DT group). All other 3D navigation performance measures were similar using the immersive and non-immersive VR systems, suggesting that the simpler desktop VR system may be useful for astronaut 3D navigation training.

Neural Network Based Sensory Fusion for Landmark Detection

NASA Technical Reports Server (NTRS)

Kumbla, Kishan -K.; Akbarzadeh, Mohammad R.

1997-01-01

NASA is planning to send numerous unmanned planetary missions to explore the space. This requires autonomous robotic vehicles which can navigate in an unstructured, unknown, and uncertain environment. Landmark based navigation is a new area of research which differs from the traditional goal-oriented navigation, where a mobile robot starts from an initial point and reaches a destination in accordance with a pre-planned path. The landmark based navigation has the advantage of allowing the robot to find its way without communication with the mission control station and without exact knowledge of its coordinates. Current algorithms based on landmark navigation however pose several constraints. First, they require large memories to store the images. Second, the task of comparing the images using traditional methods is computationally intensive and consequently real-time implementation is difficult. The method proposed here consists of three stages, First stage utilizes a heuristic-based algorithm to identify significant objects. The second stage utilizes a neural network (NN) to efficiently classify images of the identified objects. The third stage combines distance information with the classification results of neural networks for efficient and intelligent navigation.

Galileo: The Added Value for Integrity in Harsh Environments.

PubMed

Borio, Daniele; Gioia, Ciro

2016-01-16

A global navigation satellite system (GNSS)-based navigation is a challenging task in a signal-degraded environments where GNSS signals are distorted by multipath and attenuated by fading effects: the navigation solution may be inaccurate or unavailable. A possible approach to improve accuracy and availability is the joint use of measurements from different GNSSs and quality check algorithms; this approach is investigated here using live GPS and Galileo signals. A modified receiver autonomous integrity monitoring (RAIM) algorithm, including geometry and separability checks, is proposed to detect and exclude erroneous measurements: the multi-constellation approach provides redundant measurements, and RAIM exploits them to exclude distorted observations. The synergy between combined GPS/Galileo navigation and RAIM is analyzed using live data; the performance is compared to the accuracy and availability of a GPS-only solution. The tests performed demonstrate that the methods developed are effective techniques for GNSS-based navigation in signal-degraded environments. The joint use of the multi-constellation approach and of modified RAIM algorithms improves the performance of the navigation system in terms of both accuracy and availability.

Galileo: The Added Value for Integrity in Harsh Environments

PubMed Central

Borio, Daniele; Gioia, Ciro

2016-01-01

A global navigation satellite system (GNSS)-based navigation is a challenging task in a signal-degraded environments where GNSS signals are distorted by multipath and attenuated by fading effects: the navigation solution may be inaccurate or unavailable. A possible approach to improve accuracy and availability is the joint use of measurements from different GNSSs and quality check algorithms; this approach is investigated here using live GPS and Galileo signals. A modified receiver autonomous integrity monitoring (RAIM) algorithm, including geometry and separability checks, is proposed to detect and exclude erroneous measurements: the multi-constellation approach provides redundant measurements, and RAIM exploits them to exclude distorted observations. The synergy between combined GPS/Galileo navigation and RAIM is analyzed using live data; the performance is compared to the accuracy and availability of a GPS-only solution. The tests performed demonstrate that the methods developed are effective techniques for GNSS-based navigation in signal-degraded environments. The joint use of the multi-constellation approach and of modified RAIM algorithms improves the performance of the navigation system in terms of both accuracy and availability. PMID:26784205

Age-Related Differences in Associative Learning of Landmarks and Heading Directions in a Virtual Navigation Task.

PubMed

Zhong, Jimmy Y; Moffat, Scott D

2016-01-01

Previous studies have showed that spatial memory declines with age but have not clarified the relevance of different landmark cues for specifying heading directions among different age groups. This study examined differences between younger, middle-aged and older adults in route learning and memory tasks after they navigated a virtual maze that contained: (a) critical landmarks that were located at decision points (i.e., intersections) and (b) non-critical landmarks that were located at non-decision points (i.e., the sides of the route). Participants were given a recognition memory test for critical and non-critical landmarks and also given a landmark-direction associative learning task. Compared to younger adults, older adults committed more navigation errors during route learning and were poorer at associating the correct heading directions with both critical and non-critical landmarks. Notably, older adults exhibited a landmark-direction associative memory deficit at decision points; this was the first finding to show that an associative memory deficit exist among older adults in a navigational context for landmarks that are pertinent for reaching a goal, and suggest that older adults may expend more cognitive resources on the encoding of landmark/object features than on the binding of landmark and directional information. This study is also the first to show that older adults did not have a tendency to process non-critical landmarks, which were regarded as distractors/irrelevant cues for specifying the directions to reach the goal, to an equivalent or larger extent than younger adults. We explain this finding in view of the low number of non-critical cues in our virtual maze (relative to a real-world urban environment) that might not have evoked older adults' usual tendency toward processing or encoding distractors. We explain the age differences in navigational and cognitive performance with regards to functional and structural changes in the hippocampus and parahippocampus, and recommend further investigations into the functional connectivity between the prefrontal cortex and hippocampus for a better understanding of the landmark-direction associative learning among the elderly. Finally, it is hoped that the current behavioral findings will facilitate efforts to identify the neural markers of Alzheimer's disease, a disease that commonly involves navigational deficits.

Bioinspired magnetoreception and navigation using magnetic signatures as waypoints.

PubMed

Taylor, Brian K

2018-05-15

Diverse taxa use Earth's magnetic field in conjunction with other sensory modalities to accomplish navigation tasks ranging from local homing to long-distance migration across continents and ocean basins. However, despite extensive research, the mechanisms that underlie animal magnetoreception are not clearly understood, and how animals use Earth's magnetic field to navigate is an active area of investigation. Concurrently, Earth's magnetic field offers a signal that engineered systems can leverage for navigation in environments where man-made systems such as GPS are unavailable or unreliable. Using a proxy for Earth's magnetic field, and inspired by migratory animal behavior, this work implements a behavioral strategy that uses combinations of magnetic field properties as rare or unique signatures that mark specific locations. Using a discrete number of these signatures as goal waypoints, the strategy navigates through a closed set of points several times in a variety of environmental conditions, and with various levels of sensor noise. The results from this engineering/quantitative biology approach support existing notions that some animals may use combinations of magnetic properties as navigational markers, and provides insights into features and constraints that would enable navigational success or failure. The findings also offer insights into how autonomous engineered platforms might be designed to leverage the magnetic field as a navigational resource.

How vision and movement combine in the hippocampal place code.

PubMed

Chen, Guifen; King, John A; Burgess, Neil; O'Keefe, John

2013-01-02

How do external environmental and internal movement-related information combine to tell us where we are? We examined the neural representation of environmental location provided by hippocampal place cells while mice navigated a virtual reality environment in which both types of information could be manipulated. Extracellular recordings were made from region CA1 of head-fixed mice navigating a virtual linear track and running in a similar real environment. Despite the absence of vestibular motion signals, normal place cell firing and theta rhythmicity were found. Visual information alone was sufficient for localized firing in 25% of place cells and to maintain a local field potential theta rhythm (but with significantly reduced power). Additional movement-related information was required for normally localized firing by the remaining 75% of place cells. Trials in which movement and visual information were put into conflict showed that they combined nonlinearly to control firing location, and that the relative influence of movement versus visual information varied widely across place cells. However, within this heterogeneity, the behavior of fully half of the place cells conformed to a model of path integration in which the presence of visual cues at the start of each run together with subsequent movement-related updating of position was sufficient to maintain normal fields.

Intelligent Behavioral Action Aiding for Improved Autonomous Image Navigation

DTIC Science & Technology

2012-09-13

odometry, SICK laser scanning unit ( Lidar ), Inertial Measurement Unit (IMU) and ultrasonic distance measurement system (Figure 32). The Lidar , IMU...2010, July) GPS world. [Online]. http://www.gpsworld.com/tech-talk- blog/gnss-independent-navigation-solution-using-integrated- lidar -data-11378 [4...Milford, David McKinnon, Michael Warren, Gordon Wyeth, and Ben Upcroft, "Feature-based Visual Odometry and Featureless Place Recognition for SLAM in

Bio-Inspired Polarized Skylight-Based Navigation Sensors: A Review

PubMed Central

Karman, Salmah B.; Diah, S. Zaleha M.; Gebeshuber, Ille C.

2012-01-01

Animal senses cover a broad range of signal types and signal bandwidths and have inspired various sensors and bioinstrumentation devices for biological and medical applications. Insects, such as desert ants and honeybees, for example, utilize polarized skylight pattern-based information in their navigation activities. They reliably return to their nests and hives from places many kilometers away. The insect navigation system involves the dorsal rim area in their compound eyes and the corresponding polarization sensitive neurons in the brain. The dorsal rim area is equipped with photoreceptors, which have orthogonally arranged small hair-like structures termed microvilli. These are the specialized sensors for the detection of polarized skylight patterns (e-vector orientation). Various research groups have been working on the development of novel navigation systems inspired by polarized skylight-based navigation in animals. Their major contributions are critically reviewed. One focus of current research activities is on imitating the integration path mechanism in desert ants. The potential for simple, high performance miniaturized bioinstrumentation that can assist people in navigation will be explored. PMID:23202158

Bio-inspired polarized skylight-based navigation sensors: a review.

PubMed

Karman, Salmah B; Diah, S Zaleha M; Gebeshuber, Ille C

2012-10-24

Animal senses cover a broad range of signal types and signal bandwidths and have inspired various sensors and bioinstrumentation devices for biological and medical applications. Insects, such as desert ants and honeybees, for example, utilize polarized skylight pattern-based information in their navigation activities. They reliably return to their nests and hives from places many kilometers away. The insect navigation system involves the dorsal rim area in their compound eyes and the corresponding polarization sensitive neurons in the brain. The dorsal rim area is equipped with photoreceptors, which have orthogonally arranged small hair-like structures termed microvilli. These are the specialized sensors for the detection of polarized skylight patterns (e-vector orientation). Various research groups have been working on the development of novel navigation systems inspired by polarized skylight-based navigation in animals. Their major contributions are critically reviewed. One focus of current research activities is on imitating the integration path mechanism in desert ants. The potential for simple, high performance miniaturized bioinstrumentation that can assist people in navigation will be explored.

Navigation of the Galileo mission

NASA Technical Reports Server (NTRS)

Miller, L. J.; Miller, J. K.; Kirhofer, W. E.

1983-01-01

An overview of the navigation of the Galileo mission is given. Predicted navigation performance for the various mission phases is discussed with particular emphasis given to the tour phase. Orbit determination strategies and resulting accuracies are discussed for various data types. In particular, the results of combining a new Very Long Baseline Interferometry (VLBI) data type called Differential One-Way Range (DOR) with conventional radio and optical data types are presented. Maneuver strategy results include the effects of maneuver placement and various targeting methods on propellant consumption and delivery accuracy. Emphasis is placed on new results obtained using asymptote and split targeting.

Abnormal hippocampal functioning and impaired spatial navigation in depressed individuals: evidence from whole-head magnetoencephalography.

PubMed

Cornwell, Brian R; Salvadore, Giacomo; Colon-Rosario, Veronica; Latov, David R; Holroyd, Tom; Carver, Frederick W; Coppola, Richard; Manji, Husseini K; Zarate, Carlos A; Grillon, Christian

2010-07-01

Dysfunction of the hippocampus has long been suspected to be a key component of the pathophysiology of major depressive disorder. Despite evidence of hippocampal structural abnormalities in depressed patients, abnormal hippocampal functioning has not been demonstrated. The authors aimed to link spatial navigation deficits previously documented in depressed patients to abnormal hippocampal functioning using a virtual reality navigation task. Whole-head magnetoencephalography (MEG) recordings were collected while participants (19 patients diagnosed with major depressive disorder and 19 healthy subjects matched by gender and age) navigated a virtual Morris water maze to find a hidden platform; navigation to a visible platform served as a control condition. Behavioral measures were obtained to assess navigation performance. Theta oscillatory activity (4-8 Hz) was mapped across the brain on a voxel-wise basis using a spatial-filtering MEG source analysis technique. Depressed patients performed worse than healthy subjects in navigating to the hidden platform. Robust group differences in theta activity were observed in right medial temporal cortices during navigation, with patients exhibiting less engagement of the anterior hippocampus and parahippocampal cortices relative to comparison subjects. Left posterior hippocampal theta activity was positively correlated with individual performance within each group. Consistent with previous findings, depressed patients showed impaired spatial navigation. Dysfunction of right anterior hippocampus and parahippocampal cortices may underlie this deficit and stem from structural abnormalities commonly found in depressed patients.

Acute stress switches spatial navigation strategy from egocentric to allocentric in a virtual Morris water maze.

PubMed

van Gerven, Dustin J H; Ferguson, Thomas; Skelton, Ronald W

2016-07-01

Stress and stress hormones are known to influence the function of the hippocampus, a brain structure critical for cognitive-map-based, allocentric spatial navigation. The caudate nucleus, a brain structure critical for stimulus-response-based, egocentric navigation, is not as sensitive to stress. Evidence for this comes from rodent studies, which show that acute stress or stress hormones impair allocentric, but not egocentric navigation. However, there have been few studies investigating the effect of acute stress on human spatial navigation, and the results of these have been equivocal. To date, no study has investigated whether acute stress can shift human navigational strategy selection between allocentric and egocentric navigation. The present study investigated this question by exposing participants to an acute psychological stressor (the Paced Auditory Serial Addition Task, PASAT), before testing navigational strategy selection in the Dual-Strategy Maze, a modified virtual Morris water maze. In the Dual-Strategy maze, participants can chose to navigate using a constellation of extra-maze cues (allocentrically) or using a single cue proximal to the goal platform (egocentrically). Surprisingly, PASAT stress biased participants to solve the maze allocentrically significantly more, rather than less, often. These findings have implications for understanding the effects of acute stress on cognitive function in general, and the function of the hippocampus in particular. Copyright © 2016 Elsevier Inc. All rights reserved.

PandaEPL: a library for programming spatial navigation experiments.

PubMed

Solway, Alec; Miller, Jonathan F; Kahana, Michael J

2013-12-01

Recent advances in neuroimaging and neural recording techniques have enabled researchers to make significant progress in understanding the neural mechanisms underlying human spatial navigation. Because these techniques generally require participants to remain stationary, computer-generated virtual environments are used. We introduce PandaEPL, a programming library for the Python language designed to simplify the creation of computer-controlled spatial-navigation experiments. PandaEPL is built on top of Panda3D, a modern open-source game engine. It allows users to construct three-dimensional environments that participants can navigate from a first-person perspective. Sound playback and recording and also joystick support are provided through the use of additional optional libraries. PandaEPL also handles many tasks common to all cognitive experiments, including managing configuration files, logging all internal and participant-generated events, and keeping track of the experiment state. We describe how PandaEPL compares with other software for building spatial-navigation experiments and walk the reader through the process of creating a fully functional experiment.

PandaEPL: A library for programming spatial navigation experiments

PubMed Central

Solway, Alec; Miller, Jonathan F.

2013-01-01

Recent advances in neuroimaging and neural recording techniques have enabled researchers to make significant progress in understanding the neural mechanisms underlying human spatial navigation. Because these techniques generally require participants to remain stationary, computer-generated virtual environments are used. We introduce PandaEPL, a programming library for the Python language designed to simplify the creation of computer-controlled spatial-navigation experiments. PandaEPL is built on top of Panda3D, a modern open-source game engine. It allows users to construct three-dimensional environments that participants can navigate from a first-person perspective. Sound playback and recording and also joystick support are provided through the use of additional optional libraries. PandaEPL also handles many tasks common to all cognitive experiments, including managing configuration files, logging all internal and participant-generated events, and keeping track of the experiment state. We describe how PandaEPL compares with other software for building spatial-navigation experiments and walk the reader through the process of creating a fully functional experiment. PMID:23549683

Virtual wayfinding using simulated prosthetic vision in gaze-locked viewing.

PubMed

Wang, Lin; Yang, Liancheng; Dagnelie, Gislin

2008-11-01

To assess virtual maze navigation performance with simulated prosthetic vision in gaze-locked viewing, under the conditions of varying luminance contrast, background noise, and phosphene dropout. Four normally sighted subjects performed virtual maze navigation using simulated prosthetic vision in gaze-locked viewing, under five conditions of luminance contrast, background noise, and phosphene dropout. Navigation performance was measured as the time required to traverse a 10-room maze using a game controller, and the number of errors made during the trip. Navigation performance time (1) became stable after 6 to 10 trials, (2) remained similar on average at luminance contrast of 68% and 16% but had greater variation at 16%, (3) was not significantly affected by background noise, and (4) increased by 40% when 30% of phosphenes were removed. Navigation performance time and number of errors were significantly and positively correlated. Assuming that the simulated gaze-locked viewing conditions are extended to implant wearers, such prosthetic vision can be helpful for wayfinding in simple mobility tasks, though phosphene dropout may interfere with performance.

Maintaining Consistency of Spatial Information in the Hippocampal Network: A Combinatorial Geometry Model.

PubMed

Dabaghian, Y

2016-06-01

Place cells in the rat hippocampus play a key role in creating the animal's internal representation of the world. During active navigation, these cells spike only in discrete locations, together encoding a map of the environment. Electrophysiological recordings have shown that the animal can revisit this map mentally during both sleep and awake states, reactivating the place cells that fired during its exploration in the same sequence in which they were originally activated. Although consistency of place cell activity during active navigation is arguably enforced by sensory and proprioceptive inputs, it remains unclear how a consistent representation of space can be maintained during spontaneous replay. We propose a model that can account for this phenomenon and suggest that a spatially consistent replay requires a number of constraints on the hippocampal network that affect its synaptic architecture and the statistics of synaptic connection strengths.

Autonomous navigation using lunar beacons

NASA Technical Reports Server (NTRS)

Khatib, A. R.; Ellis, J.; French, J.; Null, G.; Yunck, T.; Wu, S.

1983-01-01

The concept of using lunar beacon signal transmission for on-board navigation for earth satellites and near-earth spacecraft is described. The system would require powerful transmitters on the earth-side of the moon's surface and black box receivers with antennae and microprocessors placed on board spacecraft for autonomous navigation. Spacecraft navigation requires three position and three velocity elements to establish location coordinates. Two beacons could be soft-landed on the lunar surface at the limits of allowable separation and each would transmit a wide-beam signal with cones reaching GEO heights and be strong enough to be received by small antennae in near-earth orbit. The black box processor would perform on-board computation with one-way Doppler/range data and dynamical models. Alternatively, GEO satellites such as the GPS or TDRSS spacecraft can be used with interferometric techniques to provide decimeter-level accuracy for aircraft navigation.

Navigation of space VLBI missions: Radioastron and VSOP

NASA Technical Reports Server (NTRS)

Ellis, Jordan

1993-01-01

In the mid-1990s, Russian and Japanese space agencies will each place into highly elliptic earth orbit a radio telescope consisting of a large antenna and radio astronomy receivers. Very long baseline interferometry (VLBI) techniques will be used to obtain high resolution images of radio sources observed by the space and ground based antennas. Stringent navigation accuracy requirements are imposed on the space VLBI missions by the need to transfer an ultra-stable ground reference frequency standard to the spacecraft and by the demands of the VLBI correlation process. Orbit determination for the mission will be the joint responsibility of navigation centers in the U.S., Russia, and Japan with orbit estimates based on combining tracking data from NASA, Russian, and Japanese sites. This paper describes the operational plans, the inter-agency coordination, and data exchange between the navigation centers required for space VLBI navigation.

Guidance, Navigation and Control Digital Emulation Technology Laboratory. Volume 1. Part 2. Task 1: Digital Emulation Technology Laboratory

DTIC Science & Technology

1991-09-27

AD-A241 692 II I] II I11 ANNUAL REPORT VOLUME 1 PART 2 TASK 1: DIGITAL EMULATION TECHNOLOGY LABORATOIRY REPORT NO. AR-0142-91-001 September 27, 1991... DIGITAL EMULATION TECHNOLOGY LABORATORY Contract No. DASG60-89-C-0142 Sponsored By The United States Army ? trategic Defense Command COMPUTER...ANNUAL REPORT VOLUME 1 PART 2 TASK 1: DIGITAL EMULATION TECHNOLOGY LABORATORY September 27, 1991 Authors Thomas R. Collins and Stephen R. Wachtel

Objective measure of pilot workload

NASA Technical Reports Server (NTRS)

Kantowitz, B. H.

1984-01-01

Timesharing behavior in a data-entry task, similar to a pilot entering navigation data into an on-board computer is investigated. Auditory reaction time as a function of stimulus information and dimensionality is examined. This study has direct implications for stimulus selection for secondary tasks used in the GAT flight simulator at Ames Research Center. Attenuation effects of heat and cold stress in a psychological refractory period task were studied. The focus of interest is the general effects of stress on attention rather than upon specific temperature related phenomena.

Visual navigation in adolescents with early periventricular lesions: knowing where, but not getting there.

PubMed

Pavlova, Marina; Sokolov, Alexander; Krägeloh-Mann, Ingeborg

2007-02-01

Visual navigation in familiar and unfamiliar surroundings is an essential ingredient of adaptive daily life behavior. Recent brain imaging work helps to recognize that establishing connectivity between brain regions is of importance for successful navigation. Here, we ask whether the ability to navigate is impaired in adolescents who were born premature and suffer congenital bilateral periventricular brain damage that might affect the pathways interconnecting subcortical structures with cortex. Performance on a set of visual labyrinth tasks was significantly worse in patients with periventricular leukomalacia (PVL) as compared with premature-born controls without lesions and term-born adolescents. The ability for visual navigation inversely relates to the severity of motor disability, leg-dominated bilateral spastic cerebral palsy. This agrees with the view that navigation ability substantially improves with practice and might be compromised in individuals with restrictions in active spatial exploration. Visual navigation is negatively linked to the volumetric extent of lesions over the right parietal and frontal periventricular regions. Whereas impairments of visual processing of point-light biological motion are associated in patients with PVL with bilateral parietal periventricular lesions, navigation ability is specifically linked to the frontal lesions in the right hemisphere. We suggest that more anterior periventricular lesions impair the interrelations between the right hippocampus and cortical areas leading to disintegration of neural networks engaged in visual navigation. For the first time, we show that the severity of right frontal periventricular damage and leg-dominated motor disorders can serve as independent predictors of the visual navigation disability.

Navigating Streams of Paper.

ERIC Educational Resources Information Center

Bennett-Abney, Cheryl

2001-01-01

Three organizational tools for counselors are described: three-ring binder for notes, forms, and schedules; daily log of time and activities; and a tickler file with tasks arranged by days of the week. (SK)

A Mobile App (BEDSide Mobility) to Support Nurses' Tasks at the Patient's Bedside: Usability Study.

PubMed

Ehrler, Frederic; Weinhold, Thomas; Joe, Jonathan; Lovis, Christian; Blondon, Katherine

2018-03-21

The introduction of clinical information systems has increased the amount of clinical documentation. Although this documentation generally improves patient safety, it has become a time-consuming task for nurses, which limits their time with the patient. On the basis of a user-centered methodology, we have developed a mobile app named BEDSide Mobility to support nurses in their daily workflow and to facilitate documentation at the bedside. The aim of the study was to assess the usability of the BEDSide Mobility app in terms of the navigation and interaction design through usability testing. Nurses were asked to complete a scenario reflecting their daily work with patients. Their interactions with the app were captured with eye-tracking glasses and by using the think aloud protocol. After completing the tasks, participants filled out the system usability scale questionnaire. Descriptive statistics were used to summarize task completion rates and the users' performance. A total of 10 nurses (aged 21-50) participated in the study. Overall, they were satisfied with the navigation, layout, and interaction design of the app, with the exception of one user who was unfamiliar with smartphones. The problems identified were related to the ambiguity of some icons, the navigation logic, and design inconsistency. Besides the usability issues identified in the app, the participants' results do indicate good usability, high acceptance, and high satisfaction with the developed app. However, the results must be taken with caution because of the poor ecological validity of the experimental setting. ©Frederic Ehrler, Thomas Weinhold, Jonathan Joe, Christian Lovis, Katherine Blondon. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 21.03.2018.

Remembering to learn: independent place and journey coding mechanisms contribute to memory transfer.

PubMed

Bahar, Amir S; Shapiro, Matthew L

2012-02-08

The neural mechanisms that integrate new episodes with established memories are unknown. When rats explore an environment, CA1 cells fire in place fields that indicate locations. In goal-directed spatial memory tasks, some place fields differentiate behavioral histories ("journey-dependent" place fields) while others do not ("journey-independent" place fields). To investigate how these signals inform learning and memory for new and familiar episodes, we recorded CA1 and CA3 activity in rats trained to perform a "standard" spatial memory task in a plus maze and in two new task variants. A "switch" task exchanged the start and goal locations in the same environment; an "altered environment" task contained unfamiliar local and distal cues. In the switch task, performance was mildly impaired, new firing maps were stable, but the proportion and stability of journey-dependent place fields declined. In the altered environment, overall performance was strongly impaired, new firing maps were unstable, and stable proportions of journey-dependent place fields were maintained. In both tasks, memory errors were accompanied by a decline in journey codes. The different dynamics of place and journey coding suggest that they reflect separate mechanisms and contribute to distinct memory computations. Stable place fields may represent familiar relationships among environmental features that are required for consistent memory performance. Journey-dependent activity may correspond with goal-directed behavioral sequences that reflect expectancies that generalize across environments. The complementary signals could help link current events with established memories, so that familiarity with either a behavioral strategy or an environment can inform goal-directed learning.

REMEMBERING TO LEARN: INDEPENDENT PLACE AND JOURNEY CODING MECHANISMS CONTRIBUTE TO MEMORY TRANSFER

PubMed Central

Bahar, Amir S.; Shapiro, Matthew L.

2012-01-01

The neural mechanisms that integrate new episodes with established memories are unknown. When rats explore an environment, CA1 cells fire in place fields that indicate locations. In goal-directed spatial memory tasks, some place fields differentiate behavioral histories (journey-dependent place fields) while others do not (journey-independent place fields). To investigate how these signals inform learning and memory for new and familiar episodes, we recorded CA1 and CA3 activity in rats trained to perform a standard spatial memory task in a plus maze and in two new task variants. A switch task exchanged the start and goal locations in the same environment; an altered environment task contained unfamiliar local and distal cues. In the switch task, performance was mildly impaired, new firing maps were stable, but the proportion and stability of journey-dependent place fields declined. In the altered environment, overall performance was strongly impaired, new firing maps were unstable, and stable proportions of journey-dependent place fields were maintained. In both tasks, memory errors were accompanied by a decline in journey codes. The different dynamics of place and journey coding suggest that they reflect separate mechanisms and contribute to distinct memory computations. Stable place fields may represent familiar relationships among environmental features that are required for consistent memory performance. Journey-dependent activity may correspond with goal directed behavioral sequences that reflect expectancies that generalize across environments. The complementary signals could help link current events with established memories, so that familiarity with either a behavioral strategy or an environment can inform goal-directed learning. PMID:22323731

The effect of general anesthesia versus intravenous sedation on diagnostic yield and success in electromagnetic navigation bronchoscopy.

PubMed

Bowling, Mark R; Kohan, Matthew W; Walker, Paul; Efird, Jimmy; Ben Or, Sharon

2015-01-01

Navigational bronchoscopy is utilized to guide biopsies of peripheral lung nodules and place fiducial markers for treatment of limited stage lung cancer with stereotactic body radiotherapy. The type of sedation used for this procedure remains controversial. We performed a retrospective chart review to evaluate the differences of diagnostic yield and overall success of the procedure based on anesthesia type. Electromagnetic navigational bronchoscopy was performed using the superDimension software system. Once the targeted lesion was within reach, multiple tissue samples were obtained. Statistical analysis was used to correlate the yield with the type of sedation among other factors. A successful procedure was defined if a diagnosis was made or a fiducial marker was adequately placed. Navigational bronchoscopy was performed on a total of 120 targeted lesions. The overall complication rate of the procedure was 4.1%. The diagnostic yield and success of the procedure was 74% and 87%, respectively. Duration of the procedure was the only significant difference between the general anesthesia and IV sedation groups (mean, 58 vs. 43 min, P=0.0005). A larger tumor size was associated with a higher diagnostic yield (P=0.032). All other variables in terms of effect on diagnostic yield and an unsuccessful procedure did not meet statistical significance. Navigational bronchoscopy is a safe and effective pulmonary diagnostic tool with relatively low complication rate. The diagnostic yield and overall success of the procedure does not seem to be affected by the type of sedation used.

Lay Patient Navigators' Perspectives of Barriers, Facilitators and Training Needs in Initiating Advance Care Planning Conversations With Older Patients With Cancer.

PubMed

Niranjan, Soumya J; Huang, Chao-Hui S; Dionne-Odom, J Nicholas; Halilova, Karina I; Pisu, Maria; Drentea, Patricia; Kvale, Elizabeth A; Bevis, Kerri S; Butler, Thomas W; Partridge, Edward E; Rocque, Gabrielle B

2018-04-01

Respecting Choices is an evidence-based model of facilitating advance care planning (ACP) conversations between health-care professionals and patients. However, the effectiveness of whether lay patient navigators can successfully initiate Respecting Choices ACP conversations is unknown. As part of a large demonstration project (Patient Care Connect [PCC]), a cohort of lay patient navigators underwent Respecting Choices training and were tasked to initiate ACP conversations with Medicare beneficiaries diagnosed with cancer. This article explores PCC lay navigators' perceived barriers and facilitators in initiating Respecting Choices ACP conversations with older patients with cancer in order to inform implementation enhancements to lay navigator-facilitated ACP. Twenty-six lay navigators from 11 PCC cancer centers in 4 states (Alabama, George, Tennessee, and Florida) completed in-depth, one-on-one semistructured interviews between June 2015 and August 2015. Data were analyzed using a thematic analysis approach. This evaluation identifies 3 levels-patient, lay navigator, and organizational factors in addition to training needs that influence ACP implementation. Key facilitators included physician buy-in, patient readiness, and navigators' prior experience with end-of-life decision-making. Lay navigators' perceived challenges to initiating ACP conversations included timing of the conversation and social and personal taboos about discussing dying. Our results suggest that further training and health system support are needed for lay navigators playing a vital role in improving the implementation of ACP among older patients with cancer. The lived expertise of lay navigators along with flexible longitudinal relationships with patients and caregivers may uniquely position this workforce to promote ACP.

Comparative Cohort Study of Percutaneous Pedicle Screw Implantation without Versus with Navigation in Patients Undergoing Surgery for Degenerative Lumbar Disc Disease.

PubMed

Fomekong, Edward; Pierrard, Julien; Raftopoulos, Christian

2018-03-01

The major limitation of computer-based three-dimensional fluoroscopy is increased radiation exposure of patients and operating room staff. Combining spine navigation with intraoperative three-dimensional fluoroscopy (io3DF) can likely overcome this shortcoming, while increasing pedicle screw accuracy rate. We compared data from a cohort of patients undergoing lumbar percutaneous pedicle screw placement using io3DF alone or in combination with spine navigation. This study consisted of 168 patients who underwent percutaneous pedicle screw implantation between 2009 and 2016. The primary endpoint was to compare pedicle screw accuracy between the 2 groups. Secondary endpoints were to compare radiation exposure of patients and operating room staff, duration of surgery, and postoperative complications. In group 1, 438 screws were placed without navigation guidance; in group 2, 276 screws were placed with spine navigation. Mean patient age in both groups was 58.6 ± 14.1 years. The final pedicle accuracy rate was 97.9% in group 1 and 99.6% in group 2. Average radiation dose per patient was significantly larger in group 1 (571.9 mGym 2 ) than in group 2 (365.6 mGym 2 ) (P = 0.000088). Surgery duration and complication rate were not significantly different between the 2 groups (P > 0.05). io3DF with spine navigation minimized radiation exposure of patients and operating room staff and provided an excellent percutaneous pedicle screw accuracy rate with no permanent complications compared with io3DF alone. This setup is recommended, especially for patients with a complex degenerative spine condition. Copyright © 2017 Elsevier Inc. All rights reserved.

Navigation of robotic system using cricket motes

NASA Astrophysics Data System (ADS)

Patil, Yogendra J.; Baine, Nicholas A.; Rattan, Kuldip S.

2011-06-01

This paper presents a novel algorithm for self-mapping of the cricket motes that can be used for indoor navigation of autonomous robotic systems. The cricket system is a wireless sensor network that can provide indoor localization service to its user via acoustic ranging techniques. The behavior of the ultrasonic transducer on the cricket mote is studied and the regions where satisfactorily distance measurements can be obtained are recorded. Placing the motes in these regions results fine-grain mapping of the cricket motes. Trilateration is used to obtain a rigid coordinate system, but is insufficient if the network is to be used for navigation. A modified SLAM algorithm is applied to overcome the shortcomings of trilateration. Finally, the self-mapped cricket motes can be used for navigation of autonomous robotic systems in an indoor location.

Similarities and differences between the brain networks underlying allocentric and egocentric spatial learning in rat revealed by cytochrome oxidase histochemistry.

PubMed

Rubio, S; Begega, A; Méndez, M; Méndez-López, M; Arias, J L

2012-10-25

The involvement of different brain regions in place- and response-learning was examined using a water cross-maze. Rats were trained to find the goal from the initial arm by turning left at the choice point (egocentric strategy) or by using environmental cues (allocentric strategy). Although different strategies were required, the same maze and learning conditions were used. Using cytochrome oxidase histochemistry as a marker of cellular activity, the function of the 13 diverse cortical and subcortical regions was assessed in rats performing these two tasks. Our results show that allocentric learning depends on the recruitment of a large functional network, which includes the hippocampal CA3, dentate gyrus, medial mammillary nucleus and supramammillary nucleus. Along with the striatum, these last three structures are also related to egocentric spatial learning. The present study provides evidence for the contribution of these regions to spatial navigation and supports a possible functional interaction between the two memory systems, as their structural convergence may facilitate functional cooperation in the behaviours guided by more than one strategy. In summary, it can be argued that spatial learning is based on dynamic functional systems in which the interaction of brain regions is modulated by task requirements. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

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

PubMed

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.

Place and contingency differential responses of monkey septal neurons during conditional place-object discrimination.

PubMed

Kita, T; Nishijo, H; Eifuku, S; Terasawa, K; Ono, T

1995-03-01

To elucidate spatial and cognitive function of the septal nuclei, neural activity was recorded from alert monkeys during performance of a place-dependent go/no-go (PGN) task. Response/reinforcement contingencies of given objects were conditional upon the location of a motorized, movable device (cab) containing a monkey in one of four places. The task was initiated by presentation of the outside view (place phase) followed by presentation of an object (object phase) selected from a total of four. A lever press was reinforced only if the correct object was seen in its corresponding place, and the same object was never reinforced in any of the other three places. Of 430 septal neurons recorded, the responses during the place phase in the four places were significantly different in 58 neurons. Responses of eight of these neurons were also place-differential during the object phase as well as the place phase. Furthermore, when the outside view was not presented before the object phase, differential responses in the object phase disappeared. Responses of 91 neurons in the object phase were differential in terms of go/no-go responses and reward availability. Of these 91 neurons, 72 were further tested on a place-independent asymmetrical go/no-go (AGN) task, which required no conditional discrimination. Forty-three neurons responded differentially only in the PGN task. It is thus concluded that this PGN-specific activity reflected conditional place-object relations. Of the remaining 29 neurons that responded differentially in both tasks, 21 were further tested by a place-independent symmetrical go/no-go task (no-go responses were also rewarded). Responses of 19 of these 21 neurons were related to the reward/nonreward contingency but not to the response contingency. The results suggest that septal nuclei are involved in integrating spatial information, conditional place-object relations, and reward/nonreward contingency.

Factor and Organizational Substitutions to Minimize Costs in the Navy

DTIC Science & Technology

2013-12-01

navigation, propulsion, combat, hotel , communications, in-service support and any system corresponding to further tasks such as transport, hospital...propulsion, combat, hotel , communications, in-service support and any system corresponding to further tasks such as transport, hospital services and command...contract, a cadet may be able to increase her branch choice priority. The Officer Career Satisfaction Program (OCSP) is an incentive program with

Manipulations of Start and Food Locations Affect Navigation on a Foraging Task

ERIC Educational Resources Information Center

Martin, Gerard M.; Pirzada, Ashar; Bridger, Alexander; Tomlin, Julian; Thorpe, Christina M.; Skinner, Darlene M.

2011-01-01

Rats were able to search multiple food cups in a foraging task and successfully return to a fixed, but not a variable, start location. Reducing the number of food cups to be searched resulted in an improvement in performance in the variable start condition. Performance was better when only one or two food cups had to be visited but was still…

Human Factors Engineering #3 Crewstation Assessment for the OH-58F Helicopter

DTIC Science & Technology

2014-03-01

Additionally, workload was assessed for level of interoperability 2 (LOI 2) tasks that the aircrew performed with an unmanned aircraft system (UAS...TTP tactics, techniques, and procedures UAS unmanned aircraft system 47 VFR visual flight rules VMC visual meteorological conditions VTR...For example, pilots often perform navigation tasks, communicate via multiple radios, monitor aircraft systems , and assist the pilot on the controls

A smart multisensor approach to assist blind people in specific urban navigation tasks.

PubMed

Ando, B

2008-12-01

Visually impaired people are often discouraged in using electronic aids due to complexity of operation, large amount of training, nonoptimized degree of information provided to the user, and high cost. In this paper, a new multisensor architecture is discussed, which would help blind people to perform urban mobility tasks. The device is based on a multisensor strategy and adopts smart signal processing.

Space-based navigation for RLVs and ELVs

DOT National Transportation Integrated Search

2006-02-08

The Aerospace Corporation was tasked by the Volpe National Transportation System Center to provide technical support to the Federal Aviation Administration, Office of the Associate Administrator for Commercial Space Transportation (FAA/AST), by perfo...

Virtual Reality: An Instructional Medium for Visual-Spatial Tasks.

ERIC Educational Resources Information Center

Regian, J. Wesley; And Others

1992-01-01

Describes an empirical exploration of the instructional potential of virtual reality as an interface for simulation-based training. Shows that subjects learned spatial-procedural and spatial-navigational skills in virtual reality. (SR)

Navigation of a care and welfare robot

NASA Astrophysics Data System (ADS)

Yukawa, Toshihiro; Hosoya, Osamu; Saito, Naoki; Okano, Hideharu

2005-12-01

In this paper, we propose the development of a robot that can perform nursing tasks in a hospital. In a narrow environment such as a sickroom or a hallway, the robot must be able to move freely in arbitrary directions. Therefore, the robot needs to have high controllability and the capability to make precise movements. Our robot can recognize a line by using cameras, and can be controlled in the reference directions by means of comparison with original cell map information; furthermore, it moves safely on the basis of an original center-line established permanently in the building. Correspondence between the robot and a centralized control center enables the robot's autonomous movement in the hospital. Through a navigation system using cell map information, the robot is able to perform nursing tasks smoothly by changing the camera angle.

Optimizing Mars Airplane Trajectory with the Application Navigation System

NASA Technical Reports Server (NTRS)

Frumkin, Michael; Riley, Derek

2004-01-01

Planning complex missions requires a number of programs to be executed in concert. The Application Navigation System (ANS), developed in the NAS Division, can execute many interdependent programs in a distributed environment. We show that the ANS simplifies user effort and reduces time in optimization of the trajectory of a martian airplane. We use a software package, Cart3D, to evaluate trajectories and a shortest path algorithm to determine the optimal trajectory. ANS employs the GridScape to represent the dynamic state of the available computer resources. Then, ANS uses a scheduler to dynamically assign ready task to machine resources and the GridScape for tracking available resources and forecasting completion time of running tasks. We demonstrate system capability to schedule and run the trajectory optimization application with efficiency exceeding 60% on 64 processors.

Using a contextualized sensemaking model for interaction design: A case study of tumor contouring.

PubMed

Aselmaa, Anet; van Herk, Marcel; Laprie, Anne; Nestle, Ursula; Götz, Irina; Wiedenmann, Nicole; Schimek-Jasch, Tanja; Picaud, Francois; Syrykh, Charlotte; Cagetti, Leonel V; Jolnerovski, Maria; Song, Yu; Goossens, Richard H M

2017-01-01

Sensemaking theories help designers understand the cognitive processes of a user when he/she performs a complicated task. This paper introduces a two-step approach of incorporating sensemaking support within the design of health information systems by: (1) modeling the sensemaking process of physicians while performing a task, and (2) identifying software interaction design requirements that support sensemaking based on this model. The two-step approach is presented based on a case study of the tumor contouring clinical task for radiotherapy planning. In the first step of the approach, a contextualized sensemaking model was developed to describe the sensemaking process based on the goal, the workflow and the context of the task. In the second step, based on a research software prototype, an experiment was conducted where three contouring tasks were performed by eight physicians respectively. Four types of navigation interactions and five types of interaction sequence patterns were identified by analyzing the gathered interaction log data from those twenty-four cases. Further in-depth study on each of the navigation interactions and interaction sequence patterns in relation to the contextualized sensemaking model revealed five main areas for design improvements to increase sensemaking support. Outcomes of the case study indicate that the proposed two-step approach was beneficial for gaining a deeper understanding of the sensemaking process during the task, as well as for identifying design requirements for better sensemaking support. Copyright © 2016. Published by Elsevier Inc.

Data mining for personal navigation

NASA Astrophysics Data System (ADS)

Hariharan, Gurushyam; Franti, Pasi; Mehta, Sandeep

2002-03-01

Relevance is the key in defining what data is to be extracted from the Internet. Traditionally, relevance has been defined mainly by keywords and user profiles. In this paper we discuss a fairly untouched dimension to relevance: location. Any navigational information sought by a user at large on earth is evidently governed by his location. We believe that task oriented data mining of the web amalgamated with location information is the key to providing relevant information for personal navigation. We explore the existential hurdles and propose novel approaches to tackle them. We also present naive, task-oriented data mining based approaches and their implementations in Java, to extract location based information. Ad-hoc pairing of data with coordinates (x, y) is very rare on the web. But if the same co-ordinates are converted to a logical address (state/city/street), a wide spectrum of location-based information base opens up. Hence, given the coordinates (x, y) on the earth, the scheme points to the logical address of the user. Location based information could either be picked up from fixed and known service providers (e.g. Yellow Pages) or from any arbitrary website on the Web. Once the web servers providing information relevant to the logical address are located, task oriented data mining is performed over these sites keeping in mind what information is interesting to the contemporary user. After all this, a simple data stream is provided to the user with information scaled to his convenience. The scheme has been implemented for cities of Finland.

Laparoscopic assistance by operating room nurses: Results of a virtual-reality study.

PubMed

Paschold, M; Huber, T; Maedge, S; Zeissig, S R; Lang, H; Kneist, W

2017-04-01

Laparoscopic assistance is often entrusted to a less experienced resident, medical student, or operating room nurse. Data regarding laparoscopic training for operating room nurses are not available. The aim of the study was to analyse the initial performance level and learning curves of operating room nurses in basic laparoscopic surgery compared with medical students and surgical residents to determine their ability to assist with this type of procedure. The study was designed to compare the initial virtual reality performance level and learning curves of user groups to analyse competence in laparoscopic assistance. The study subjects were operating room nurses, medical students, and first year residents. Participants performed three validated tasks (camera navigation, peg transfer, fine dissection) on a virtual reality laparoscopic simulator three times in 3 consecutive days. Laparoscopic experts were enrolled as a control group. Participants filled out questionnaires before and after the course. Nurses and students were comparable in their initial performance (p>0.05). Residents performed better in camera navigation than students and nurses and reached the expert level for this task. Residents, students, and nurses had comparable bimanual skills throughout the study; while, experts performed significantly better in bimanual manoeuvres at all times (p<0.05). The included user groups had comparable skills for bimanual tasks. Residents with limited experience reached the expert level in camera navigation. With training, nurses, students, and first year residents are equally capable of assisting in basic laparoscopic procedures. Copyright © 2017 Elsevier Ltd. All rights reserved.

Verbalizing, Visualizing, and Navigating: The Effect of Strategies on Encoding a Large-Scale Virtual Environment

PubMed Central

Kraemer, David J.M.; Schinazi, Victor R.; Cawkwell, Philip B.; Tekriwal, Anand; Epstein, Russell A.; Thompson-Schill, Sharon L.

2016-01-01

Using novel virtual cities, we investigated the influence of verbal and visual strategies on the encoding of navigation-relevant information in a large-scale virtual environment. In two experiments, participants watched videos of routes through four virtual cities and were subsequently tested on their memory for observed landmarks and on their ability to make judgments regarding the relative directions of the different landmarks along the route. In the first experiment, self-report questionnaires measuring visual and verbal cognitive styles were administered to examine correlations between cognitive styles, landmark recognition, and judgments of relative direction. Results demonstrate a tradeoff in which the verbal cognitive style is more beneficial for recognizing individual landmarks than for judging relative directions between them, whereas the visual cognitive style is more beneficial for judging relative directions than for landmark recognition. In a second experiment, we manipulated the use of verbal and visual strategies by varying task instructions given to separate groups of participants. Results confirm that a verbal strategy benefits landmark memory, whereas a visual strategy benefits judgments of relative direction. The manipulation of strategy by altering task instructions appears to trump individual differences in cognitive style. Taken together, we find that processing different details during route encoding, whether due to individual proclivities (Experiment 1) or task instructions (Experiment 2), results in benefits for different components of navigation relevant information. These findings also highlight the value of considering multiple sources of individual differences as part of spatial cognition investigations. PMID:27668486

Cheap or Robust? The practical realization of self-driving wheelchair technology.

PubMed

Burhanpurkar, Maya; Labbe, Mathieu; Guan, Charlie; Michaud, Francois; Kelly, Jonathan

2017-07-01

To date, self-driving experimental wheelchair technologies have been either inexpensive or robust, but not both. Yet, in order to achieve real-world acceptance, both qualities are fundamentally essential. We present a unique approach to achieve inexpensive and robust autonomous and semi-autonomous assistive navigation for existing fielded wheelchairs, of which there are approximately 5 million units in Canada and United States alone. Our prototype wheelchair platform is capable of localization and mapping, as well as robust obstacle avoidance, using only a commodity RGB-D sensor and wheel odometry. As a specific example of the navigation capabilities, we focus on the single most common navigation problem: the traversal of narrow doorways in arbitrary environments. The software we have developed is generalizable to corridor following, desk docking, and other navigation tasks that are either extremely difficult or impossible for people with upper-body mobility impairments.

Orbit Determination and Navigation Software Testing for the Mars Reconnaissance Orbiter

NASA Technical Reports Server (NTRS)

Pini, Alex

2011-01-01

During the extended science phase of the Mars Reconnaissance Orbiter's lifecycle, the operational duties pertaining to navigation primarily involve orbit determination. The orbit determination process utilizes radiometric tracking data and is used for the prediction and reconstruction of MRO's trajectories. Predictions are done twice per week for ephemeris updates on-board the spacecraft and for planning purposes. Orbit Trim Maneuvers (OTM-s) are also designed using the predicted trajectory. Reconstructions, which incorporate a batch estimator, provide precise information about the spacecraft state to be synchronized with scientific measurements. These tasks were conducted regularly to validate the results obtained by the MRO Navigation Team. Additionally, the team is in the process of converting to newer versions of the navigation software and operating system. The capability to model multiple densities in the Martian atmosphere is also being implemented. However, testing outputs among these different configurations was necessary to ensure compliance to a satisfactory degree.

Temporal order memory assessed during spatiotemporal navigation as a behavioral cognitive marker for differential Alzheimer's disease diagnosis.

PubMed

Bellassen, Virginie; Iglói, Kinga; de Souza, Leonardo Cruz; Dubois, Bruno; Rondi-Reig, Laure

2012-02-08

Episodic memory impairment is a hallmark for early diagnosis of Alzheimer's disease. Most actual tests used to diagnose Alzheimer's disease do not assess the spatiotemporal properties of episodic memory and lead to false-positive or -negative diagnosis. We used a newly developed, nonverbal navigation test for Human, based on the objective experimental testing of a spatiotemporal experience, to differentially Alzheimer's disease at the mild stage (N = 16 patients) from frontotemporal lobar degeneration (N = 11 patients) and normal aging (N = 24 subjects). Comparing navigation parameters and standard neuropsychological tests, temporal order memory appeared to have the highest predictive power for mild Alzheimer's disease diagnosis versus frontotemporal lobar degeneration and normal aging. This test was also nonredundant with classical neuropsychological tests. As a conclusion, our results suggest that temporal order memory tested in a spatial navigation task may provide a selective behavioral marker of Alzheimer's disease.

Navigation skill impairment: Another dimension of the driving difficulties in minimal hepatic encephalopathy.

PubMed

Bajaj, Jasmohan S; Hafeezullah, Muhammad; Hoffmann, Raymond G; Varma, Rajiv R; Franco, Jose; Binion, David G; Hammeke, Thomas A; Saeian, Kia

2008-02-01

Patients with minimal hepatic encephalopathy (MHE) have attention, response inhibition, and working memory difficulties that are associated with driving impairment and high motor vehicle accident risk. Navigation is a complex system needed for safe driving that requires functioning working memory and other domains adversely affected by MHE. The aim of this study was to determine the effect of MHE on navigation skills and correlate them with psychometric impairment. Forty-nine nonalcoholic patients with cirrhosis (34 MHE+, 15 MHE-; divided on the basis of a battery of block design, digit symbol, and number connection test A) and 48 age/education-matched controls were included. All patients underwent the psychometric battery and inhibitory control test (ICT) (a test of response inhibition) and driving simulation. Driving simulation consisted of 4 parts: (1) training; (2) driving (outcome being accidents); (3) divided attention (outcome being missed tasks); and (4) navigation, driving along a marked path on a map in a "virtual city" (outcome being illegal turns). Illegal turns were significantly higher in MHE+ (median 1; P = 0.007) compared with MHE-/controls (median 0). Patients who were MHE+ missed more divided attention tasks compared with others (median MHE+ 1, MHE-/controls 0; P = 0.001). Similarly, accidents were higher in patients who were MHE+ (median 2.5; P = 0.004) compared with MHE- (median 1) or controls (median 2). Accidents and illegal turns were significantly correlated (P = 0.001, r = 0.51). ICT impairment was the test most correlated with illegal turns (r = 0.6) and accidents (r = 0.44), although impairment on the other tests were also correlated with illegal turns. Patients positive for MHE have impaired navigation skills on a driving simulator, which is correlated with impairment in response inhibition (ICT) and attention. This navigation difficulty may pose additional driving problems, compounding the pre-existing deleterious effect of attention deficits.

Spatial learning, monoamines and oxidative stress in rats exposed to 900 MHz electromagnetic field in combination with iron overload.

PubMed

Maaroufi, Karima; Had-Aissouni, Laurence; Melon, Christophe; Sakly, Mohsen; Abdelmelek, Hafedh; Poucet, Bruno; Save, Etienne

2014-01-01

The increasing use of mobile phone technology over the last decade raises concerns about the impact of high frequency electromagnetic fields (EMF) on health. More recently, a link between EMF, iron overload in the brain and neurodegenerative disorders including Parkinson's and Alzheimer's diseases has been suggested. Co-exposure to EMF and brain iron overload may have a greater impact on brain tissues and cognitive processes than each treatment by itself. To examine this hypothesis, Long-Evans rats submitted to 900 MHz exposure or combined 900 MHz EMF and iron overload treatments were tested in various spatial learning tasks (navigation task in the Morris water maze, working memory task in the radial-arm maze, and object exploration task involving spatial and non spatial processing). Biogenic monoamines and metabolites (dopamine, serotonin) and oxidative stress were measured. Rats exposed to EMF were impaired in the object exploration task but not in the navigation and working memory tasks. They also showed alterations of monoamine content in several brain areas but mainly in the hippocampus. Rats that received combined treatment did not show greater behavioral and neurochemical deficits than EMF-exposed rats. None of the two treatments produced global oxidative stress. These results show that there is an impact of EMF on the brain and cognitive processes but this impact is revealed only in a task exploiting spontaneous exploratory activity. In contrast, there are no synergistic effects between EMF and a high content of iron in the brain. Copyright © 2013 Elsevier B.V. All rights reserved.

Usefulness of virtual reality in assessment of medical student laparoscopic skill.

PubMed

Matzke, Josh; Ziegler, Craig; Martin, Kevin; Crawford, Stuart; Sutton, Erica

2017-05-01

This study evaluates if undergraduate medical trainees' laparoscopic skills acquisition could be assessed using a virtual reality (VR) simulator and how the resultant metrics correlate with performance of Fundamentals of Laparoscopic Surgery (FLS) tasks. Our hypothesis is that the VR simulator metrics will correlate with passing results in a competency-based curriculum (FLS). Twenty-eight fourth-year medical students applying for surgical residency were recruited to participate in a VR training curriculum comprised of camera navigation, hand eye coordination, and FLS tasks: circle cutting (CC), ligating loop (LL), peg transfer (PT), and intracorporeal knot tying (IKT). Students were given 8 wk to achieve proficiency goals, after which they were observed performing FLS tasks. The ability of the VR simulator to detect penalties in each of the FLS tasks and correlations of time taken to complete tasks are reported. Twenty-five students trained in all components of the curriculum. All students were proficient in camera navigation and hand eye coordination tasks. Proficiency was achieved in CC, LL, PT, and IKT by 21, 19, 23, and one student, respectively. VR simulation showed high specificity for predicting zero penalties on the observed CC, LL, and PT tasks (80%, 75%, and 80%, respectively). VR can be used to assess medical student's acquisition of laparoscopic skills. The absence of penalties in the simulator reasonably predicts the absence of penalties in all FLS skills, except IKT. The skills acquired by trainees can be used in residency for further monitoring of progress toward proficiency. Copyright © 2016 Elsevier Inc. All rights reserved.

A Low-Cost, Passive Navigation Training System for Image-Guided Spinal Intervention.

PubMed

Lorias-Espinoza, Daniel; Carranza, Vicente González; de León, Fernando Chico-Ponce; Escamirosa, Fernando Pérez; Martinez, Arturo Minor

2016-11-01

Navigation technology is used for training in various medical specialties, not least image-guided spinal interventions. Navigation practice is an important educational component that allows residents to understand how surgical instruments interact with complex anatomy and to learn basic surgical skills such as the tridimensional mental interpretation of bidimensional data. Inexpensive surgical simulators for spinal surgery, however, are lacking. We therefore designed a low-cost spinal surgery simulator (Spine MovDigSys 01) to allow 3-dimensional navigation via 2-dimensional images without altering or limiting the surgeon's natural movement. A training system was developed with an anatomical lumbar model and 2 webcams to passively digitize surgical instruments under MATLAB software control. A proof-of-concept recognition task (vertebral body cannulation) and a pilot test of the system with 12 neuro- and orthopedic surgeons were performed to obtain feedback on the system. Position, orientation, and kinematic variables were determined and the lateral, posteroanterior, and anteroposterior views obtained. The system was tested with a proof-of-concept experimental task. Operator metrics including time of execution (t), intracorporeal length (d), insertion angle (α), average speed (v¯), and acceleration (a) were obtained accurately. These metrics were converted into assessment metrics such as smoothness of operation and linearity of insertion. Results from initial testing are shown and the system advantages and disadvantages described. This low-cost spinal surgery training system digitized the position and orientation of the instruments and allowed image-guided navigation, the generation of metrics, and graphic recording of the instrumental route. Spine MovDigSys 01 is useful for development of basic, noninnate skills and allows the novice apprentice to quickly and economically move beyond the basics. Copyright © 2016 Elsevier Inc. All rights reserved.

Enabling automated magnetic resonance imaging-based targeting assessment during dipole field navigation

NASA Astrophysics Data System (ADS)

Latulippe, Maxime; Felfoul, Ouajdi; Dupont, Pierre E.; Martel, Sylvain

2016-02-01

The magnetic navigation of drugs in the vascular network promises to increase the efficacy and reduce the secondary toxicity of cancer treatments by targeting tumors directly. Recently, dipole field navigation (DFN) was proposed as the first method achieving both high field and high navigation gradient strengths for whole-body interventions in deep tissues. This is achieved by introducing large ferromagnetic cores around the patient inside a magnetic resonance imaging (MRI) scanner. However, doing so distorts the static field inside the scanner, which prevents imaging during the intervention. This limitation constrains DFN to open-loop navigation, thus exposing the risk of a harmful toxicity in case of a navigation failure. Here, we are interested in periodically assessing drug targeting efficiency using MRI even in the presence of a core. We demonstrate, using a clinical scanner, that it is in fact possible to acquire, in specific regions around a core, images of sufficient quality to perform this task. We show that the core can be moved inside the scanner to a position minimizing the distortion effect in the region of interest for imaging. Moving the core can be done automatically using the gradient coils of the scanner, which then also enables the core to be repositioned to perform navigation to additional targets. The feasibility and potential of the approach are validated in an in vitro experiment demonstrating navigation and assessment at two targets.

Dynamic clearance measure to evaluate locomotor and perceptuo-motor strategies used for obstacle circumvention in a virtual environment.

PubMed

Darekar, Anuja; Lamontagne, Anouk; Fung, Joyce

2015-04-01

Circumvention around an obstacle entails a dynamic interaction with the obstacle to maintain a safe clearance. We used a novel mathematical interpolation method based on the modified Shepard's method of Inverse Distance Weighting to compute dynamic clearance that reflected this interaction as well as minimal clearance. This proof-of-principle study included seven young healthy, four post-stroke and four healthy age-matched individuals. A virtual environment designed to assess obstacle circumvention was used to administer a locomotor (walking) and a perceptuo-motor (navigation with a joystick) task. In both tasks, participants were asked to navigate towards a target while avoiding collision with a moving obstacle that approached from either head-on, or 30° left or right. Among young individuals, dynamic clearance did not differ significantly between obstacle approach directions in both tasks. Post-stroke individuals maintained larger and smaller dynamic clearance during the locomotor and the perceptuo-motor task respectively as compared to age-matched controls. Dynamic clearance was larger than minimal distance from the obstacle irrespective of the group, task and obstacle approach direction. Also, in contrast to minimal distance, dynamic clearance can respond differently to different avoidance behaviors. Such a measure can be beneficial in contrasting obstacle avoidance behaviors in different populations with mobility problems. Copyright © 2015 Elsevier B.V. All rights reserved.

Examining Teacher Attrition and Other Related Issues: A Conversation with Dr. D. Ray Reutzel

ERIC Educational Resources Information Center

Martin, Linda E.; Mulvihill, Thalia M.

2016-01-01

Teacher educators work diligently to prepare future teachers while navigating the surrounding political realities that challenge our schools. Demands placed on teacher educators are growing and are increasingly more complex. Well-prepared and successful teachers are exiting the profession at alarming rates in several places in the world, including…

33 CFR 83.21 - Definitions (Rule 21).

Code of Federal Regulations, 2012 CFR

2012-07-01

... NAVIGATION RULES RULES Lights and Shapes § 83.21 Definitions (Rule 21). (a) Masthead light means a white... light shall be placed as nearly as practicable to the fore and aft centerline of the vessel. (b... white light placed as nearly as practicable at the stern showing an unbroken light over an arc of the...

33 CFR 83.21 - Definitions (Rule 21).

Code of Federal Regulations, 2014 CFR

2014-07-01

... NAVIGATION RULES RULES Lights and Shapes § 83.21 Definitions (Rule 21). (a) Masthead light means a white... light shall be placed as nearly as practicable to the fore and aft centerline of the vessel. (b... white light placed as nearly as practicable at the stern showing an unbroken light over an arc of the...

33 CFR 83.21 - Definitions (Rule 21).

Code of Federal Regulations, 2011 CFR

2011-07-01

... NAVIGATION RULES RULES Lights and Shapes § 83.21 Definitions (Rule 21). (a) Masthead light means a white... light shall be placed as nearly as practicable to the fore and aft centerline of the vessel. (b... white light placed as nearly as practicable at the stern showing an unbroken light over an arc of the...

Cross-Cultural Trust Networks and Advancing Education Equity in Place-Based Partnerships

ERIC Educational Resources Information Center

Banks, Amber Joy

2017-01-01

Research suggests that trust can be a foundational element for the success and sustainability of multi-organizational partnerships focused on advancing education equity in a particular neighborhood or region. As these place-based strategies gain popularity in the U.S., collaborators are increasingly required to navigate relationships where racial…

Autonomous satellite navigation with the Global Positioning System

NASA Technical Reports Server (NTRS)

Fuchs, A. J.; Wooden, W. H., II; Long, A. C.

1977-01-01

This paper discusses the potential of using the Global Positioning System (GPS) to provide autonomous navigation capability to NASA satellites in the 1980 era. Some of the driving forces motivating autonomous navigation are presented. These include such factors as advances in attitude control systems, onboard science annotation, and onboard gridding of imaging data. Simulation results which demonstrate baseline orbit determination accuracies using GPS data on Seasat, Landsat-D, and the Solar Maximum Mission are presented. Emphasis is placed on identifying error sources such as GPS time, GPS ephemeris, user timing biases, and user orbit dynamics, and in a parametric sense on evaluating their contribution to the orbit determination accuracies.

Preliminary performance analysis of an interplanetary navigation system using asteroid based beacons

NASA Technical Reports Server (NTRS)

Jee, J. Rodney; Khatib, Ahmad R.; Muellerschoen, Ronald J.; Williams, Bobby G.; Vincent, Mark A.

1988-01-01

A futuristic interplanetary navigation system using transmitters placed on selected asteroids is introduced. This network of space beacons is seen as a needed alternative to the overly burdened Deep Space Network. Covariance analyses on the potential performance of these space beacons located on a candidate constellation of eight real asteroids are initiated. Simplified analytic calculations are performed to determine limiting accuracies attainable with the network for geometric positioning. More sophisticated computer simulations are also performed to determine potential accuracies using long arcs of range and Doppler data from the beacons. The results from these computations show promise for this navigation system.

Investigation of image enhancement techniques for the development of a self-contained airborne radar navigation system

NASA Technical Reports Server (NTRS)

Phatak, A. V.; Karmali, M. S.

1983-01-01

This study was devoted to an investigation of the feasibility of applying advanced image processing techniques to enhance radar image characteristics that are pertinent to the pilot's navigation and guidance task. Millimeter (95 GHz) wave radar images for the overwater (i.e., offshore oil rigs) and overland (Heliport) scenario were used as a data base. The purpose of the study was to determine the applicability of image enhancement and scene analysis algorithms to detect and improve target characteristics (i.e., manmade objects such as buildings, parking lots, cars, roads, helicopters, towers, landing pads, etc.) that would be helpful to the pilot in determining his own position/orientation with respect to the outside world and assist him in the navigation task. Results of this study show that significant improvements in the raw radar image may be obtained using two dimensional image processing algorithms. In the overwater case, it is possible to remove the ocean clutter by thresholding the image data, and furthermore to extract the target boundary as well as the tower and catwalk locations using noise cleaning (e.g., median filter) and edge detection (e.g., Sobel operator) algorithms.

A lower ratio of omega-6 to omega-3 fatty acids predicts better hippocampus-dependent spatial memory and cognitive status in older adults.

PubMed

Andruchow, Nadia D; Konishi, Kyoko; Shatenstein, Bryna; Bohbot, Véronique D

2017-10-01

Evidence from several cross-sectional studies indicates that an increase in omega-6 to omega-3 fatty acids (FAs) may negatively affect cognition in old age. The hippocampus is among the first neural structures affected by age and atrophy in this brain region is associated with cognitive decline. Therefore, we hypothesized that a lower omega-6:3 FA ratio would predict better hippocampus-dependent spatial memory, and a higher general cognitive status. Fifty-two healthy older adults completed a Food Frequency Questionnaire, the Montreal Cognitive Assessment test (MoCA; a test of global cognition) and virtual navigation tasks that assess navigational strategies and spatial memory. In this cross-sectional study, a lower ratio of omega-6 to omega-3 FA intake strongly predicted more accurate hippocampus-dependent spatial memory and faster learning on our virtual navigation tasks, as well as higher cognitive status overall. These results may help elucidate why certain dietary patterns with a lower omega-6:3 FA ratio, like the Mediterranean diet, are associated with reduced risk of cognitive decline. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

The recognition of web pages' hyperlinks by people with intellectual disabilities: an evaluation study.

PubMed

Rocha, Tânia; Bessa, Maximino; Gonçalves, Martinho; Cabral, Luciana; Godinho, Francisco; Peres, Emanuel; Reis, Manuel C; Magalhães, Luís; Chalmers, Alan

2012-11-01

One of the most mentioned problems of web accessibility, as recognized in several different studies, is related to the difficulty regarding the perception of what is or is not clickable in a web page. In particular, a key problem is the recognition of hyperlinks by a specific group of people, namely those with intellectual disabilities. This experiment investigated a methodology based on the direct observation, video recording, interview and data obtained by an eye tracker device. Ten participants took part in this study. They were divided into two groups and asked to perform two tasks: 'Sing a song' and 'Listen to a story' in two websites. These websites were developed to include specific details. The first website presented an image navigation menu (INM), whereas the other one showed a text navigation menu (TNM). There was a general improvement regarding the participants' performance when using INMs. The referred analysis indeed shows that not only did these specific participants gain a better understanding of the demanding task, but also they showed an improved perception concerning the content of the navigation menu that included hyperlinks with images. © 2012 Blackwell Publishing Ltd.

Practical Methodology of Cognitive Tasks Within a Navigational Assessment.

PubMed

Robillard, Manon; Mayer-Crittenden, Chantal; Roy-Charland, Annie; Minor-Corriveau, Michèle; Bélanger, Roxanne

2015-06-01

This paper describes an approach for measuring navigation accuracy relative to cognitive skills. The methodology behind the assessment will thus be clearly outlined in a step-by-step manner. Navigational skills are important when trying to find symbols within a speech-generating device (SGD) that has a dynamic screen and taxonomical organization. The following skills have been found to impact children's ability to find symbols when navigating within the levels of an SGD: sustained attention, categorization, cognitive flexibility, and fluid reasoning. According to past studies, working memory was not correlated with navigation. The materials needed for this method include a computerized tablet, an augmentative and alternative communication application, a booklet of symbols, and the Leiter International Performance Scale-Revised (Leiter-R). This method has been used in two previous studies. Robillard, Mayer-Crittenden, Roy-Charland, Minor-Corriveau and Bélanger assessed typically developing children, while Rondeau, Robillard and Roy-Charland assessed children and adolescents with a diagnosis of Autism Spectrum Disorder. The direct observation of this method will facilitate the replication of this study for researchers. It will also help clinicians that work with children who have complex communication needs to determine the children's ability to navigate an SGD with taxonomical categorization.

Group navigation and the "many-wrongs principle" in models of animal movement.

PubMed

Codling, E A; Pitchford, J W; Simpson, S D

2007-07-01

Traditional studies of animal navigation over both long and short distances have usually considered the orientation ability of the individual only, without reference to the implications of group membership. However, recent work has suggested that being in a group can significantly improve the ability of an individual to align toward and reach a target direction or point, even when all group members have limited navigational ability and there are no leaders. This effect is known as the "many-wrongs principle" since the large number of individual navigational errors across the group are suppressed by interactions and group cohesion. In this paper, we simulate the many-wrongs principle using a simple individual-based model of movement based on a biased random walk that includes group interactions. We study the ability of the group as a whole to reach a target given different levels of individual navigation error, group size, interaction radius, and environmental turbulence. In scenarios with low levels of environmental turbulence, simulation results demonstrate a navigational benefit from group membership, particularly for small group sizes. In contrast, when movement takes place in a highly turbulent environment, simulation results suggest that the best strategy is to navigate as individuals rather than as a group.

SLAM algorithm applied to robotics assistance for navigation in unknown environments.

PubMed

Cheein, Fernando A Auat; Lopez, Natalia; Soria, Carlos M; di Sciascio, Fernando A; Pereira, Fernando Lobo; Carelli, Ricardo

2010-02-17

The combination of robotic tools with assistance technology determines a slightly explored area of applications and advantages for disability or elder people in their daily tasks. Autonomous motorized wheelchair navigation inside an environment, behaviour based control of orthopaedic arms or user's preference learning from a friendly interface are some examples of this new field. In this paper, a Simultaneous Localization and Mapping (SLAM) algorithm is implemented to allow the environmental learning by a mobile robot while its navigation is governed by electromyographic signals. The entire system is part autonomous and part user-decision dependent (semi-autonomous). The environmental learning executed by the SLAM algorithm and the low level behaviour-based reactions of the mobile robot are robotic autonomous tasks, whereas the mobile robot navigation inside an environment is commanded by a Muscle-Computer Interface (MCI). In this paper, a sequential Extended Kalman Filter (EKF) feature-based SLAM algorithm is implemented. The features correspond to lines and corners -concave and convex- of the environment. From the SLAM architecture, a global metric map of the environment is derived. The electromyographic signals that command the robot's movements can be adapted to the patient's disabilities. For mobile robot navigation purposes, five commands were obtained from the MCI: turn to the left, turn to the right, stop, start and exit. A kinematic controller to control the mobile robot was implemented. A low level behavior strategy was also implemented to avoid robot's collisions with the environment and moving agents. The entire system was tested in a population of seven volunteers: three elder, two below-elbow amputees and two young normally limbed patients. The experiments were performed within a closed low dynamic environment. Subjects took an average time of 35 minutes to navigate the environment and to learn how to use the MCI. The SLAM results have shown a consistent reconstruction of the environment. The obtained map was stored inside the Muscle-Computer Interface. The integration of a highly demanding processing algorithm (SLAM) with a MCI and the communication between both in real time have shown to be consistent and successful. The metric map generated by the mobile robot would allow possible future autonomous navigation without direct control of the user, whose function could be relegated to choose robot destinations. Also, the mobile robot shares the same kinematic model of a motorized wheelchair. This advantage can be exploited for wheelchair autonomous navigation.

NASA Office of Aeronautics and Space Technology Summer Workshop. Volume 3: Navigation, guidance and control panel

NASA Technical Reports Server (NTRS)

1975-01-01

User technology requirements are identified in relation to needed technology advancement for future space missions in the areas of navigation, guidance, and control. Emphasis is placed on: reduction of mission support cost by 50% through autonomous operation, a ten-fold increase in mission output through improved pointing and control, and a hundred-fold increase in human productivity in space through large-scale teleoperator applications.

Students Achieve More in New York Integrated Math AB with TI Graphing Calculators and the TI-Navigator[TM] System. Case Study 3

ERIC Educational Resources Information Center

Morse, Dana F.

2007-01-01

This study took place at Skaneateles High School in Skaneateles, New York in a grade 10 Integrated Math AB course with 52 students in 3 sections using the TI-84 Plus family graphing calculators and the TI-Navigator classroom learning system with a projector and interactive whiteboard. New York State is phasing in a new curriculum that integrates…

A Design Study of Onboard Navigation and Guidance During Aerocapture at Mars. M.S. Thesis

NASA Technical Reports Server (NTRS)

Fuhry, Douglas Paul

1988-01-01

The navigation and guidance of a high lift-to-drag ratio sample return vehicle during aerocapture at Mars are investigated. Emphasis is placed on integrated systems design, with guidance algorithm synthesis and analysis based on vehicle state and atmospheric density uncertainty estimates provided by the navigation system. The latter utilizes a Kalman filter for state vector estimation, with useful update information obtained through radar altimeter measurements and density altitude measurements based on IMU-measured drag acceleration. A three-phase guidance algorithm, featuring constant bank numeric predictor/corrector atmospheric capture and exit phases and an extended constant altitude cruise phase, is developed to provide controlled capture and depletion of orbital energy, orbital plane control, and exit apoapsis control. Integrated navigation and guidance systems performance are analyzed using a four degree-of-freedom computer simulation. The simulation environment includes an atmospheric density model with spatially correlated perturbations to provide realistic variations over the vehicle trajectory. Navigation filter initial conditions for the analysis are based on planetary approach optical navigation results. Results from a selection of test cases are presented to give insight into systems performance.

Awake craniotomy using electromagnetic navigation technology without rigid pin fixation.

PubMed

Morsy, Ahmed A; Ng, Wai Hoe

2015-11-01

We report our institutional experience using an electromagnetic navigation system, without rigid head fixation, for awake craniotomy patients. The StealthStation® S7 AxiEM™ navigation system (Medtronic, Inc.) was used for this technique. Detailed preoperative clinical and neuropsychological evaluations, patient education and contrast-enhanced MRI (thickness 1.5mm) were performed for each patient. The AxiEM Mobile Emitter was typically placed in a holder, which was mounted to the operating room table, and a non-invasive patient tracker was used as the patient reference device. A monitored conscious sedation technique was used in all awake craniotomy patients, and the AxiEM Navigation Pointer was used for navigation during the procedure. This offers the same accuracy as optical navigation, but without head pin fixation or interference with intraoperative neurophysiological techniques and surgical instruments. The application of the electromagnetic neuronavigation technology without rigid head fixation during an awake craniotomy is accurate, and offers superior patient comfort. It is recommended as an effective adjunctive technique for the conduct of awake surgery. Copyright © 2015 Elsevier Ltd. All rights reserved.

Applications of different design methodologies in navigation systems and development at JPL

NASA Technical Reports Server (NTRS)

Thurman, S. W.

1990-01-01

The NASA/JPL deep space navigation system consists of a complex array of measurement systems, data processing systems, and support facilities, with components located both on the ground and on-board interplanetary spacecraft. From its beginings nearly 30 years ago, this system has steadily evolved and grown to meet the demands for ever-increasing navigation accuracy placed on it by a succession of unmanned planetary missions. Principal characteristics of this system are its capabilities and great complexity. Three examples in the design and development of interplanetary space navigation systems are examined in order to make a brief assessment of the usefulness of three basic design theories, known as normative, rational, and heuristic. Evaluation of the examples indicates that a heuristic approach, coupled with rational-based mathematical and computational analysis methods, is used most often in problems such as orbit determination strategy development and mission navigation system design, while normative methods have seen only limited use is such applications as the development of large software systems and in the design of certain operational navigation subsystems.

Two Distinct Scene-Processing Networks Connecting Vision and Memory.

PubMed

Baldassano, Christopher; Esteva, Andre; Fei-Fei, Li; Beck, Diane M

2016-01-01

A number of regions in the human brain are known to be involved in processing natural scenes, but the field has lacked a unifying framework for understanding how these different regions are organized and interact. We provide evidence from functional connectivity and meta-analyses for a new organizational principle, in which scene processing relies upon two distinct networks that split the classically defined parahippocampal place area (PPA). The first network of strongly connected regions consists of the occipital place area/transverse occipital sulcus and posterior PPA, which contain retinotopic maps and are not strongly coupled to the hippocampus at rest. The second network consists of the caudal inferior parietal lobule, retrosplenial complex, and anterior PPA, which connect to the hippocampus (especially anterior hippocampus), and are implicated in both visual and nonvisual tasks, including episodic memory and navigation. We propose that these two distinct networks capture the primary functional division among scene-processing regions, between those that process visual features from the current view of a scene and those that connect information from a current scene view with a much broader temporal and spatial context. This new framework for understanding the neural substrates of scene-processing bridges results from many lines of research, and makes specific functional predictions.

Brain connectivity during encoding and retrieval of spatial information: individual differences in navigation skills.

PubMed

Sharma, Greeshma; Gramann, Klaus; Chandra, Sushil; Singh, Vijander; Mittal, Alok Prakash

2017-09-01

Emerging evidence suggests that the variations in the ability to navigate through any real or virtual environment are accompanied by distinct underlying cortical activations in multiple regions of the brain. These activations may appear due to the use of different frame of reference (FOR) for representing an environment. The present study investigated the brain dynamics in the good and bad navigators using Graph Theoretical analysis applied to low-density electroencephalography (EEG) data. Individual navigation skills were rated according to the performance in a virtual reality (VR)-based navigation task and the effect of navigator's proclivity towards a particular FOR on the navigation performance was explored. Participants were introduced to a novel virtual environment that they learned from a first-person or an aerial perspective and were subsequently assessed on the basis of efficiency with which they learnt and recalled. The graph theoretical parameters, path length (PL), global efficiency (GE), and clustering coefficient (CC) were computed for the functional connectivity network in the theta and alpha frequency bands. During acquisition of the spatial information, good navigators were distinguished by a lower degree of dispersion in the functional connectivity compared to the bad navigators. Within the groups of good and bad navigators, better performers were characterised by the formation of multiple hubs at various sites and the percentage of connectivity or small world index. The proclivity towards a specific FOR during exploration of a new environment was not found to have any bearing on the spatial learning. These findings may have wider implications for how the functional connectivity in the good and bad navigators differs during spatial information acquisition and retrieval in the domains of rescue operations and defence systems.

Into the Wild: Neuroergonomic Differentiation of Hand-Held and Augmented Reality Wearable Displays during Outdoor Navigation with Functional Near Infrared Spectroscopy.

PubMed

McKendrick, Ryan; Parasuraman, Raja; Murtza, Rabia; Formwalt, Alice; Baccus, Wendy; Paczynski, Martin; Ayaz, Hasan

2016-01-01

Highly mobile computing devices promise to improve quality of life, productivity, and performance. Increased situation awareness and reduced mental workload are two potential means by which this can be accomplished. However, it is difficult to measure these concepts in the "wild". We employed ultra-portable battery operated and wireless functional near infrared spectroscopy (fNIRS) to non-invasively measure hemodynamic changes in the brain's Prefrontal cortex (PFC). Measurements were taken during navigation of a college campus with either a hand-held display, or an Augmented reality wearable display (ARWD). Hemodynamic measures were also paired with secondary tasks of visual perception and auditory working memory to provide behavioral assessment of situation awareness and mental workload. Navigating with an augmented reality wearable display produced the least workload during the auditory working memory task, and a trend for improved situation awareness in our measures of prefrontal hemodynamics. The hemodynamics associated with errors were also different between the two devices. Errors with an augmented reality wearable display were associated with increased prefrontal activity and the opposite was observed for the hand-held display. This suggests that the cognitive mechanisms underlying errors between the two devices differ. These findings show fNIRS is a valuable tool for assessing new technology in ecologically valid settings and that ARWDs offer benefits with regards to mental workload while navigating, and potentially superior situation awareness with improved display design.

Into the Wild: Neuroergonomic Differentiation of Hand-Held and Augmented Reality Wearable Displays during Outdoor Navigation with Functional Near Infrared Spectroscopy

PubMed Central

McKendrick, Ryan; Parasuraman, Raja; Murtza, Rabia; Formwalt, Alice; Baccus, Wendy; Paczynski, Martin; Ayaz, Hasan

2016-01-01

Highly mobile computing devices promise to improve quality of life, productivity, and performance. Increased situation awareness and reduced mental workload are two potential means by which this can be accomplished. However, it is difficult to measure these concepts in the “wild”. We employed ultra-portable battery operated and wireless functional near infrared spectroscopy (fNIRS) to non-invasively measure hemodynamic changes in the brain’s Prefrontal cortex (PFC). Measurements were taken during navigation of a college campus with either a hand-held display, or an Augmented reality wearable display (ARWD). Hemodynamic measures were also paired with secondary tasks of visual perception and auditory working memory to provide behavioral assessment of situation awareness and mental workload. Navigating with an augmented reality wearable display produced the least workload during the auditory working memory task, and a trend for improved situation awareness in our measures of prefrontal hemodynamics. The hemodynamics associated with errors were also different between the two devices. Errors with an augmented reality wearable display were associated with increased prefrontal activity and the opposite was observed for the hand-held display. This suggests that the cognitive mechanisms underlying errors between the two devices differ. These findings show fNIRS is a valuable tool for assessing new technology in ecologically valid settings and that ARWDs offer benefits with regards to mental workload while navigating, and potentially superior situation awareness with improved display design. PMID:27242480

How the structure of Wikipedia articles influences user navigation.

PubMed

Lamprecht, Daniel; Lerman, Kristina; Helic, Denis; Strohmaier, Markus

2017-01-02

In this work we study how people navigate the information network of Wikipedia and investigate (i) free-form navigation by studying all clicks within the English Wikipedia over an entire month and (ii) goal-directed Wikipedia navigation by analyzing wikigames, where users are challenged to retrieve articles by following links. To study how the organization of Wikipedia articles in terms of layout and links affects navigation behavior, we first investigate the characteristics of the structural organization and of hyperlinks in Wikipedia and then evaluate link selection models based on article structure and other potential influences in navigation, such as the generality of an article's topic. In free-form Wikipedia navigation, covering all Wikipedia usage scenarios, we find that click choices can be best modeled by a bias towards article structure, such as a tendency to click links located in the lead section. For the goal-directed navigation of wikigames, our findings confirm the zoom-out and the homing-in phases identified by previous work, where users are guided by generality at first and textual similarity to the target later. However, our interpretation of the link selection models accentuates that article structure is the best explanation for the navigation paths in all except these initial and final stages. Overall, we find evidence that users more frequently click on links that are located close to the top of an article. The structure of Wikipedia articles, which places links to more general concepts near the top, supports navigation by allowing users to quickly find the better-connected articles that facilitate navigation. Our results highlight the importance of article structure and link position in Wikipedia navigation and suggest that better organization of information can help make information networks more navigable.

How the structure of Wikipedia articles influences user navigation

NASA Astrophysics Data System (ADS)

Lamprecht, Daniel; Lerman, Kristina; Helic, Denis; Strohmaier, Markus

2017-01-01

In this work we study how people navigate the information network of Wikipedia and investigate (i) free-form navigation by studying all clicks within the English Wikipedia over an entire month and (ii) goal-directed Wikipedia navigation by analyzing wikigames, where users are challenged to retrieve articles by following links. To study how the organization of Wikipedia articles in terms of layout and links affects navigation behavior, we first investigate the characteristics of the structural organization and of hyperlinks in Wikipedia and then evaluate link selection models based on article structure and other potential influences in navigation, such as the generality of an article's topic. In free-form Wikipedia navigation, covering all Wikipedia usage scenarios, we find that click choices can be best modeled by a bias towards article structure, such as a tendency to click links located in the lead section. For the goal-directed navigation of wikigames, our findings confirm the zoom-out and the homing-in phases identified by previous work, where users are guided by generality at first and textual similarity to the target later. However, our interpretation of the link selection models accentuates that article structure is the best explanation for the navigation paths in all except these initial and final stages. Overall, we find evidence that users more frequently click on links that are located close to the top of an article. The structure of Wikipedia articles, which places links to more general concepts near the top, supports navigation by allowing users to quickly find the better-connected articles that facilitate navigation. Our results highlight the importance of article structure and link position in Wikipedia navigation and suggest that better organization of information can help make information networks more navigable.

How the structure of Wikipedia articles influences user navigation

PubMed Central

Lamprecht, Daniel; Lerman, Kristina; Helic, Denis; Strohmaier, Markus

2017-01-01

In this work we study how people navigate the information network of Wikipedia and investigate (i) free-form navigation by studying all clicks within the English Wikipedia over an entire month and (ii) goal-directed Wikipedia navigation by analyzing wikigames, where users are challenged to retrieve articles by following links. To study how the organization of Wikipedia articles in terms of layout and links affects navigation behavior, we first investigate the characteristics of the structural organization and of hyperlinks in Wikipedia and then evaluate link selection models based on article structure and other potential influences in navigation, such as the generality of an article's topic. In free-form Wikipedia navigation, covering all Wikipedia usage scenarios, we find that click choices can be best modeled by a bias towards article structure, such as a tendency to click links located in the lead section. For the goal-directed navigation of wikigames, our findings confirm the zoom-out and the homing-in phases identified by previous work, where users are guided by generality at first and textual similarity to the target later. However, our interpretation of the link selection models accentuates that article structure is the best explanation for the navigation paths in all except these initial and final stages. Overall, we find evidence that users more frequently click on links that are located close to the top of an article. The structure of Wikipedia articles, which places links to more general concepts near the top, supports navigation by allowing users to quickly find the better-connected articles that facilitate navigation. Our results highlight the importance of article structure and link position in Wikipedia navigation and suggest that better organization of information can help make information networks more navigable. PMID:28670171

Mapping the navigational knowledge of individually foraging ants, Myrmecia croslandi

PubMed Central

Narendra, Ajay; Gourmaud, Sarah; Zeil, Jochen

2013-01-01

Ants are efficient navigators, guided by path integration and visual landmarks. Path integration is the primary strategy in landmark-poor habitats, but landmarks are readily used when available. The landmark panorama provides reliable information about heading direction, routes and specific location. Visual memories for guidance are often acquired along routes or near to significant places. Over what area can such locally acquired memories provide information for reaching a place? This question is unusually approachable in the solitary foraging Australian jack jumper ant, since individual foragers typically travel to one or two nest-specific foraging trees. We find that within 10 m from the nest, ants both with and without home vector information available from path integration return directly to the nest from all compass directions, after briefly scanning the panorama. By reconstructing panoramic views within the successful homing range, we show that in the open woodland habitat of these ants, snapshot memories acquired close to the nest provide sufficient navigational information to determine nest-directed heading direction over a surprisingly large area, including areas that animals may have not visited previously. PMID:23804615

A technical innovation for improving identification of the trackers by the LED cameras in navigation-assisted total knee arthroplasty.

PubMed

Darmanis, Spyridon; Toms, Andrew; Durman, Robert; Moore, Donna; Eyres, Keith

2007-07-01

To reduce the operating time in computer-assisted navigated total knee replacement (TKR), by improving communication between the infrared camera and the trackers placed on the patient. The innovation involves placing a routinely used laser pointer on top of the camera, so that the infrared cameras focus precisely on the trackers located on the knee to be operated on. A prospective randomized study was performed involving 40 patients divided into two groups, A and B. Both groups underwent navigated TKR, but for group B patients a laser pointer was used to improve the targeting capabilities of the cameras. Without the laser pointer, the camera had to move a mean 9.2 times in order to identify the trackers. With the introduction of the laser pointer, this was reduced to 0.9 times. Accordingly, the additional mean time required without the laser pointer was 11.6 minutes. Time delays are a major problem in computer-assisted surgery, and our technical suggestion can contribute towards reducing the delays associated with this particular application.

76 FR 68097 - Certifications and Exemptions Under the International Regulations for Preventing Collisions at...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-03

... functions. List of Subjects in 32 CFR Part 706 Marine safety, Navigation (water), and Vessels. Accordingly... out of alignment alignment with the the upper and middle upper and middle task task light in meters light in meters by: by: USV 11MUCO601 0.85 11MUCO602 0.85 11MUCO603 0.85 11MUCO604 0.85 USS FORT WORTH...

Magnifying Smartphone Screen Using Google Glass for Low-Vision Users.

PubMed

Pundlik, Shrinivas; HuaQi Yi; Rui Liu; Peli, Eli; Gang Luo

2017-01-01

Magnification is a key accessibility feature used by low-vision smartphone users. However, small screen size can lead to loss of context and make interaction with magnified displays challenging. We hypothesize that controlling the viewport with head motion can be natural and help in gaining access to magnified displays. We implement this idea using a Google Glass that displays the magnified smartphone screenshots received in real time via Bluetooth. Instead of navigating with touch gestures on the magnified smartphone display, the users can view different screen locations by rotating their head, and remotely interacting with the smartphone. It is equivalent to looking at a large virtual image through a head contingent viewing port, in this case, the Glass display with ~ 15 ° field of view. The system can transfer seven screenshots per second at 8 × magnification, sufficient for tasks where the display content does not change rapidly. A pilot evaluation of this approach was conducted with eight normally sighted and four visually impaired subjects performing assigned tasks using calculator and music player apps. Results showed that performance in the calculation task was faster with the Glass than with the phone's built-in screen zoom. We conclude that head contingent scanning control can be beneficial in navigating magnified small smartphone displays, at least for tasks involving familiar content layout.

Augmented Reality to Preserve Hidden Vestiges in Historical Cities. a Case Study

NASA Astrophysics Data System (ADS)

Martínez, J. L.; Álvareza, S.; Finat, J.; Delgado, F. J.; Finat, J.

2015-02-01

Mobile devices provide an increasingly sophisticated support to enhanced experiences and understanding the remote past in an interactive way. The use of augmented reality technologies allows to develop mobile applications for indoor exploration of virtually reconstructed archaeological places. In our work we have built a virtual reconstruction of a Roman Villa with data arising from an urgent partial excavation which were performed in order to build a car parking in the historical city of Valladolid (Spain). In its current state, the archaeological site is covered by an urban garden. Localization and tracking are performed using a combination of GPS and inertial sensors of the mobile device. In this work we prove how to perform an interactive navigation around the 3D virtual model showing an interpretation of the way it was. The user experience is enhanced by answering some simple questions, performing minor tasks and puzzles which are presented with multimedia contents linked to key features of the archaeological site.

Beyond the Dedicated Education Unit: Using Cognitive Load Theory to Guide Clinical Placement.

PubMed

Mulcock, Pamela McPhie; Grassley, Jane; Davis, Michael; White, Kathryn

2017-02-01

Navigating multiple instructors and clinical agencies can impair students' learning by increasing their cognitive load and perceived stress. This study used cognitive load theory to guide the home base clinical model (HBCM), which assigned students to the same faculty and hospital unit for two consecutive medical-surgical clinical courses. The study used a quasi-experimental three-group design to evaluate the effects of the HBCM on students' perceived stress, compared with groups who changed hospital or instructor. A 10-point visual analog scale measured students' perceived stress on nine clinical tasks. The study recruited 140 participants. Reductions in mean stress were greater for the HBCM groups than the other two groups. The study findings challenge the current practice of placing students with changing faculty and facilities. The HBCM demonstrates potential as an effective model for increasing students' ability to learn by decreasing their cognitive load and subsequent stress in their clinical placements. [J Nurs Educ. 2017;56(2):105-109.]. Copyright 2017, SLACK Incorporated.

Air Force construction automation/robotics

NASA Technical Reports Server (NTRS)

Nease, A. D.; Alexander, E. F.

1993-01-01

The Air Force has several missions which generate unique requirements that are being met through the development of construction robotic technology. One especially important mission will be the conduct of Department of Defense (DOD) space activities. Space operations and other missions place construction/repair equipment operators in dangerous environments and potentially harmful situations. Additionally, force reductions require that human resources be leveraged to the maximum extent possible, and more stringent construction repair requirements push for increased automation. To solve these problems, the U.S. Air Force is undertaking a research and development effort at Tyndall AFB, FL, to develop robotic construction/repair equipment. This development effort involves the following technologies: teleoperation, telerobotics, construction operations (excavation, grading, leveling, tool change), robotic vehicle communications, vehicle navigation, mission/vehicle task control architecture, and associated computing environment. The ultimate goal is the fielding of a robotic repair capability operating at the level of supervised autonomy. This paper will discuss current and planned efforts in space construction/repair, explosive ordnance disposal, hazardous waste cleanup, and fire fighting.

Sublayer-Specific Coding Dynamics during Spatial Navigation and Learning in Hippocampal Area CA1.

PubMed

Danielson, Nathan B; Zaremba, Jeffrey D; Kaifosh, Patrick; Bowler, John; Ladow, Max; Losonczy, Attila

2016-08-03

The mammalian hippocampus is critical for spatial information processing and episodic memory. Its primary output cells, CA1 pyramidal cells (CA1 PCs), vary in genetics, morphology, connectivity, and electrophysiological properties. It is therefore possible that distinct CA1 PC subpopulations encode different features of the environment and differentially contribute to learning. To test this hypothesis, we optically monitored activity in deep and superficial CA1 PCs segregated along the radial axis of the mouse hippocampus and assessed the relationship between sublayer dynamics and learning. Superficial place maps were more stable than deep during head-fixed exploration. Deep maps, however, were preferentially stabilized during goal-oriented learning, and representation of the reward zone by deep cells predicted task performance. These findings demonstrate that superficial CA1 PCs provide a more stable map of an environment, while their counterparts in the deep sublayer provide a more flexible representation that is shaped by learning about salient features in the environment. VIDEO ABSTRACT. Copyright © 2016 Elsevier Inc. All rights reserved.

Voyager flight engineering - Preparing for Uranus

NASA Technical Reports Server (NTRS)

Mclaughlin, W. I.; Wolff, D. M.

1985-01-01

Two Voyager spacecraft are currently engaged in exploration of the outer solar system with Voyager 2 scheduled to conduct the first close-up investigation of the planet Uranus during the period November 4, 1985 through March 3, 1986. Flight engineering for the Voyager project has the objectives of delivering a functioning spacecraft containing observing sequences to the right places at the right times. Due to the changing environment as the mission has progressed outward from Jupiter to Saturn to Uranus (and on to Neptune), this engineering task has included the development of significant new capabilities. The paper utilizes the case-study method to examine some new spacecraft capabilities in three subsystems: data, attitude and articulation control, and power. The implementation of a new navigational data-type, delta DOR, is also reviewed. An overview is given of the Voyager sequencing process for the cruise and encounter phases with a case study focusing on late updating of part of the near encounter sequence. The prospective mission to Neptune is previewed.

Toward a practical mobile robotic aid system for people with severe physical disabilities.

PubMed

Regalbuto, M A; Krouskop, T A; Cheatham, J B

1992-01-01

A simple, relatively inexpensive robotic system that can aid severely disabled persons by providing pick-and-place manipulative abilities to augment the functions of human or trained animal assistants is under development at Rice University and the Baylor College of Medicine. A stand-alone software application program runs on a Macintosh personal computer and provides the user with a selection of interactive windows for commanding the mobile robot via cursor action. A HERO 2000 robot has been modified such that its workspace extends from the floor to tabletop heights, and the robot is interfaced to a Macintosh SE via a wireless communications link for untethered operation. Integrated into the system are hardware and software which allow the user to control household appliances in addition to the robot. A separate Machine Control Interface device converts breath action and head or other three-dimensional motion inputs into cursor signals. Preliminary in-home and laboratory testing has demonstrated the utility of the system to perform useful navigational and manipulative tasks.

KIN-Nav navigation system for kinematic assessment in anterior cruciate ligament reconstruction: features, use, and perspectives.

PubMed

Martelli, S; Zaffagnini, S; Bignozzi, S; Lopomo, N F; Iacono, F; Marcacci, M

2007-10-01

In this paper a new navigation system, KIN-Nav, developed for research and used during 80 anterior cruciate ligament (ACL) reconstructions is described. KIN-Nav is a user-friendly navigation system for flexible intraoperative acquisitions of anatomical and kinematic data, suitable for validation of biomechanical hypotheses. It performs real-time quantitative evaluation of antero-posterior, internal-external, and varus-valgus knee laxity at any degree of flexion and provides a new interface for this task, suitable also for comparison of pre-operative and post-operative knee laxity and surgical documentation. In this paper the concept and features of KIN-Nav, which represents a new approach to navigation and allows the investigation of new quantitative measurements in ACL reconstruction, are described. Two clinical studies are reported, as examples of clinical potentiality and correct use of this methodology. In this paper a preliminary analysis of KIN-Nav's reliability and clinical efficacy, performed during blinded repeated measures by three independent examiners, is also given. This analysis is the first assessment of the potential of navigation systems for evaluating knee kinematics.

Engagement of neural circuits underlying 2D spatial navigation in a rodent virtual reality system

PubMed Central

Aronov, Dmitriy; Tank, David W.

2015-01-01

SUMMARY Virtual reality (VR) enables precise control of an animal’s environment and otherwise impossible experimental manipulations. Neural activity in navigating rodents has been studied on virtual linear tracks. However, the spatial navigation system’s engagement in complete two-dimensional environments has not been shown. We describe a VR setup for rats, including control software and a large-scale electrophysiology system, which supports 2D navigation by allowing animals to rotate and walk in any direction. The entorhinal-hippocampal circuit, including place cells, grid cells, head direction cells and border cells, showed 2D activity patterns in VR similar to those in the real world. Hippocampal neurons exhibited various remapping responses to changes in the appearance or the shape of the virtual environment, including a novel form in which a VR-induced cue conflict caused remapping to lock to geometry rather than salient cues. These results suggest a general-purpose tool for novel types of experimental manipulations in navigating rats. PMID:25374363

Navigating the flow: individual and continuum models for homing in flowing environments

PubMed Central

Painter, Kevin J.; Hillen, Thomas

2015-01-01

Navigation for aquatic and airborne species often takes place in the face of complicated flows, from persistent currents to highly unpredictable storms. Hydrodynamic models are capable of simulating flow dynamics and provide the impetus for much individual-based modelling, in which particle-sized individuals are immersed into a flowing medium. These models yield insights on the impact of currents on population distributions from fish eggs to large organisms, yet their computational demands and intractability reduce their capacity to generate the broader, less parameter-specific, insights allowed by traditional continuous approaches. In this paper, we formulate an individual-based model for navigation within a flowing field and apply scaling to derive its corresponding macroscopic and continuous model. We apply it to various movement classes, from drifters that simply go with the flow to navigators that respond to environmental orienteering cues. The utility of the model is demonstrated via its application to ‘homing’ problems and, in particular, the navigation of the marine green turtle Chelonia mydas to Ascension Island. PMID:26538557

Orbit Determination and Navigation of the Time History of Events and Macroscale Interactions during Substorms (THEMIS)

NASA Technical Reports Server (NTRS)

Morinelli, Patrick; Cosgrove, Jennifer; Blizzard, Mike; Robertson, Mike

2007-01-01

This paper provides an overview of the launch and early orbit activities performed by the NASA Goddard Space Flight Center's (GSFC) Flight Dynamics Facility (FDF) in support of five probes comprising the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft. The FDF was tasked to support THEMIS in a limited capacity providing backup orbit determination support for validation purposes for all five THEMIS probes during launch plus 30 days in coordination with University of California Berkeley Flight Dynamics Center (UCB/FDC)2. The FDF's orbit determination responsibilities were originally planned to be as a backup to the UCB/FDC for validation purposes only. However, various challenges early on in the mission and a Spacecraft Emergency declared thirty hours after launch placed the FDF team in the role of providing the orbit solutions that enabled contact with each of the probes and the eventual termination of the Spacecraft Emergency. This paper details the challenges and various techniques used by the GSFC FDF team to successfully perform orbit determination for all five THEMIS probes during the early mission. In addition, actual THEMIS orbit determination results are presented spanning the launch and early orbit mission phase. Lastly, this paper enumerates lessons learned from the THEMIS mission, as well as demonstrates the broad range of resources and capabilities within the FDF for supporting critical launch and early orbit navigation activities, especially challenging for constellation missions.

Orbit Determination and Navigation of the Time History of Events and Macroscale Interactions during Substorms (THEMIS)

NASA Technical Reports Server (NTRS)

Morinelli, Patrick; Cosgrove, jennifer; Blizzard, Mike; Nicholson, Ann; Robertson, Mika

2007-01-01

This paper provides an overview of the launch and early orbit activities performed by the NASA Goddard Space Flight Center's (GSFC) Flight Dynamics Facility (FDF) in support of five probes comprising the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft. The FDF was tasked to support THEMIS in a limited capacity providing backup orbit determination support for validation purposes for all five THEMIS probes during launch plus 30 days in coordination with University of California Berkeley Flight Dynamics Center (UCB/FDC). The FDF's orbit determination responsibilities were originally planned to be as a backup to the UCB/FDC for validation purposes only. However, various challenges early on in the mission and a Spacecraft Emergency declared thirty hours after launch placed the FDF team in the role of providing the orbit solutions that enabled contact with each of the probes and the eventual termination of the Spacecraft Emergency. This paper details the challenges and various techniques used by the GSFC FDF team to successfully perform orbit determination for all five THEMIS probes during the early mission. In addition, actual THEMIS orbit determination results are presented spanning the launch and early orbit mission phase. Lastly, this paper enumerates lessons learned from the THEMIS mission, as well as demonstrates the broad range of resources and capabilities within the FDF for supporting critical launch and early orbit navigation activities, especially challenging for constellation missions.

Human factors assessment of SC-214 message set

DOT National Transportation Integrated Search

2010-08-18

This is a presentation that was given at the Communication Navigation and Surveillance (CNS) Task Force Meeting. It discusses a review of current literature, analysis of Pilot Deviations and ASRS reports involving data link communications, and discus...

A preliminary study of sex differences in brain activation during a spatial navigation task in healthy adults.

PubMed

Sneider, Jennifer Tropp; Sava, Simona; Rogowska, Jadwiga; Yurgelun-Todd, Deborah A

2011-10-01

The hippocampus plays a significant role in spatial memory processing, with sex differences being prominent on various spatial tasks. This study examined sex differences in healthy adults, using functional magnetic resonance imaging (fMRI) in areas implicated in spatial processing during navigation of a virtual analogue of the Morris water-maze. There were three conditions: learning, hidden, and visible control. There were no significant differences in performance measures. However, sex differences were found in regional brain activation during learning in the right hippocampus, right parahippocampal gyrus, and the cingulate cortex. During the hidden condition, the hippocampus, parahippocampal gyrus, and cingulate cortex were activated in both men and women. Additional brain areas involved in spatial processing may be recruited in women when learning information about the environment, by utilizing external cues (landmarks) more than do men, contributing to the observed sex differences in brain activation.

Flight Crew Task Management in Non-Normal Situations

NASA Technical Reports Server (NTRS)

Schutte, Paul C.; Trujillo, Anna C.

1996-01-01

Task management (TM) is always performed on the flight deck, although not always explicitly, consistently, or rigorously. Nowhere is TM as important as it is in dealing with non-normal situations. The objective of this study was to analyze pilot TM behavior for non-normal situations. Specifically, the study observed pilots performance in a full workload environment in order to discern their TM strategies. This study identified four different TM prioritization and allocation strategies: Aviate-Navigate-Communicate-Manage Systems; Perceived Severity; Procedure Based; and Event/Interrupt Driven. Subjects used these strategies to manage their personal workload and to schedule monitoring and assessment of the situation. The Perceived Severity strategy for personal workload management combined with the Aviate-Navigate-Communicate-Manage Systems strategy for monitoring and assessing appeared to be the most effective (fewest errors and fastest response times) in responding to the novel system failure used in this study.