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Sample records for human spatial navigation

  1. 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

  2. Right-lateralized brain oscillations in human spatial navigation.

    PubMed

    Jacobs, Joshua; Korolev, Igor O; Caplan, Jeremy B; Ekstrom, Arne D; Litt, Brian; Baltuch, Gordon; Fried, Itzhak; Schulze-Bonhage, Andreas; Madsen, Joseph R; Kahana, Michael J

    2010-05-01

    During spatial navigation, lesion and functional imaging studies suggest that the right hemisphere has a unique functional role. However, studies of direct human brain recordings have not reported interhemisphere differences in navigation-related oscillatory activity. We investigated this apparent discrepancy using intracranial electroencephalographic recordings from 24 neurosurgical patients playing a virtual taxi driver game. When patients were virtually moving in the game, brain oscillations at various frequencies increased in amplitude compared with periods of virtual stillness. Using log-linear analysis, we analyzed the region and frequency specificities of this pattern and found that neocortical movement-related gamma oscillations (34-54 Hz) were significantly lateralized to the right hemisphere, especially in posterior neocortex. We also observed a similar right lateralization of gamma oscillations related to searching for objects at unknown virtual locations. Thus, our results indicate that gamma oscillations in the right neocortex play a special role in human spatial navigation.

  3. Lost in Virtual Space: Studies in Human and Ideal Spatial Navigation

    ERIC Educational Resources Information Center

    Stankiewicz, Brian J.; Legge, Gordon E.; Mansfield, J. Stephen; Schlicht, Erik J.

    2006-01-01

    The authors describe 3 human spatial navigation experiments that investigate how limitations of perception, memory, uncertainty, and decision strategy affect human spatial navigation performance. To better understand the effect of these variables on human navigation performance, the authors developed an ideal-navigator model for indoor navigation…

  4. Lost in Virtual Space: Studies in Human and Ideal Spatial Navigation

    ERIC Educational Resources Information Center

    Stankiewicz, Brian J.; Legge, Gordon E.; Mansfield, J. Stephen; Schlicht, Erik J.

    2006-01-01

    The authors describe 3 human spatial navigation experiments that investigate how limitations of perception, memory, uncertainty, and decision strategy affect human spatial navigation performance. To better understand the effect of these variables on human navigation performance, the authors developed an ideal-navigator model for indoor navigation…

  5. Robust encoding of scene anticipation during human spatial navigation

    PubMed Central

    Shikauchi, Yumi; Ishii, Shin

    2016-01-01

    In a familiar city, people can recall scene views (e.g., a particular street corner scene) they could encounter again in the future. Complex objects with multiple features are represented by multiple neural units (channels) in the brain, but when anticipating a scene view, the kind of feature that is assigned to a specific channel is unknown. Here, we studied neural encoding of scene view anticipation during spatial navigation, using a novel data-driven analysis to evaluate encoding channels. Our encoding models, based on functional magnetic resonance imaging (fMRI) activity, provided channel error correction via redundant channel assignments that reflected the navigation environment. We also found that our encoding models strongly reflected brain activity in the inferior parietal gyrus and precuneus, and that details of future scenes were locally represented in the superior prefrontal gyrus and temporal pole. Furthermore, a decoder associated with the encoding models accurately predicted future scene views in both passive and active navigation. These results suggest that the human brain uses scene anticipation, mediated especially by parietal and medial prefrontal cortical areas, as a robust and effective navigation processing. PMID:27874089

  6. Direct recordings of grid-like neuronal activity in human spatial navigation

    PubMed Central

    Weidemann, Christoph T.; Miller, Jonathan F.; Solway, Alec; Burke, John; Wei, Xue-Xin; Suthana, Nanthia; Sperling, Michael; Sharan, Ashwini D.

    2013-01-01

    Grid cells in the entorhinal cortex appear to represent spatial location via a triangular coordinate system. Such cells, which have been identified in rats, bats, and monkeys, are believed to support a wide range of spatial behaviors. By recording neuronal activity from neurosurgical patients performing a virtual-navigation task we identified cells exhibiting grid-like spiking patterns in the human brain, suggesting that humans and simpler animals rely on homologous spatial-coding schemes. PMID:23912946

  7. Does field independence predict visuo-spatial abilities underpinning human navigation? Behavioural evidence.

    PubMed

    Boccia, Maddalena; Piccardi, Laura; Di Marco, Mariangela; Pizzamiglio, Luigi; Guariglia, Cecilia

    2016-10-01

    Field independence (FI) has been defined as the extent to which the individual perceives part of a field as discrete from the surrounding field, rather than embedded in the field. It has been proposed to represent a relatively stable pattern in individuals' predisposition towards information processing. In the present study, we assessed the effect of FI on skills underpinning human navigation. Fifty Healthy individuals took part in this study. FI has been assessed by using the group embedded figures test (GEFT). Participants were also asked to perform several visuo-spatial orientation tasks, including the perspective taking/spatial orientation test (PTSOT), the mental rotation task (MRT) and the vividness task, as well as the Santa Barbara Sense of Direction Scale, a self-reported questionnaire, which has been found to predict environmental spatial orientation ability. We found that performances on the GEFT significantly predicted performances on the PTSOT and the MRT. This result supports the idea that FI predicts human navigation.

  8. Spatial cognition and navigation

    NASA Technical Reports Server (NTRS)

    Aretz, Anthony J.

    1989-01-01

    An experiment that provides data for the development of a cognitive model of pilot flight navigation is described. The experiment characterizes navigational awareness as the mental alignment of two frames of reference: (1) the ego centered reference frame that is established by the forward view out of the cockpit and (2) the world centered reference frame that is established by the aircraft's location on a map. The data support a model involving at least two components: (1) the perceptual encoding of the navigational landmarks and (2) the mental rotation of the map's world reference frame into alignment with the ego centered reference frame. The quantitative relationships of these two factors are provided as possible inputs for a computational model of spatial cognition during flight navigation.

  9. Spatial cognition and navigation

    NASA Technical Reports Server (NTRS)

    Aretz, Anthony J.

    1989-01-01

    An experiment that provides data for the development of a cognitive model of pilot flight navigation is described. The experiment characterizes navigational awareness as the mental alignment of two frames of reference: (1) the ego centered reference frame that is established by the forward view out of the cockpit and (2) the world centered reference frame that is established by the aircraft's location on a map. The data support a model involving at least two components: (1) the perceptual encoding of the navigational landmarks and (2) the mental rotation of the map's world reference frame into alignment with the ego centered reference frame. The quantitative relationships of these two factors are provided as possible inputs for a computational model of spatial cognition during flight navigation.

  10. Hippocampal Volume Reduction in Humans Predicts Impaired Allocentric Spatial Memory in Virtual-Reality Navigation

    PubMed Central

    Dzieciol, Anna M.; Gadian, David G.; Jentschke, Sebastian; Doeller, Christian F.; Burgess, Neil; Mishkin, Mortimer

    2015-01-01

    The extent to which navigational spatial memory depends on hippocampal integrity in humans is not well documented. We investigated allocentric spatial recall using a virtual environment in a group of patients with severe hippocampal damage (SHD), a group of patients with “moderate” hippocampal damage (MHD), and a normal control group. Through four learning blocks with feedback, participants learned the target locations of four different objects in a circular arena. Distal cues were present throughout the experiment to provide orientation. A circular boundary as well as an intra-arena landmark provided spatial reference frames. During a subsequent test phase, recall of all four objects was tested with only the boundary or the landmark being present. Patients with SHD were impaired in both phases of this task. Across groups, performance on both types of spatial recall was highly correlated with memory quotient (MQ), but not with intelligence quotient (IQ), age, or sex. However, both measures of spatial recall separated experimental groups beyond what would be expected based on MQ, a widely used measure of general memory function. Boundary-based and landmark-based spatial recall were both strongly related to bilateral hippocampal volumes, but not to volumes of the thalamus, putamen, pallidum, nucleus accumbens, or caudate nucleus. The results show that boundary-based and landmark-based allocentric spatial recall are similarly impaired in patients with SHD, that both types of recall are impaired beyond that predicted by MQ, and that recall deficits are best explained by a reduction in bilateral hippocampal volumes. SIGNIFICANCE STATEMENT In humans, bilateral hippocampal atrophy can lead to profound impairments in episodic memory. Across species, perhaps the most well-established contribution of the hippocampus to memory is not to episodic memory generally but to allocentric spatial memory. However, the extent to which navigational spatial memory depends on

  11. Hippocampal Volume Reduction in Humans Predicts Impaired Allocentric Spatial Memory in Virtual-Reality Navigation.

    PubMed

    Guderian, Sebastian; Dzieciol, Anna M; Gadian, David G; Jentschke, Sebastian; Doeller, Christian F; Burgess, Neil; Mishkin, Mortimer; Vargha-Khadem, Faraneh

    2015-10-21

    The extent to which navigational spatial memory depends on hippocampal integrity in humans is not well documented. We investigated allocentric spatial recall using a virtual environment in a group of patients with severe hippocampal damage (SHD), a group of patients with "moderate" hippocampal damage (MHD), and a normal control group. Through four learning blocks with feedback, participants learned the target locations of four different objects in a circular arena. Distal cues were present throughout the experiment to provide orientation. A circular boundary as well as an intra-arena landmark provided spatial reference frames. During a subsequent test phase, recall of all four objects was tested with only the boundary or the landmark being present. Patients with SHD were impaired in both phases of this task. Across groups, performance on both types of spatial recall was highly correlated with memory quotient (MQ), but not with intelligence quotient (IQ), age, or sex. However, both measures of spatial recall separated experimental groups beyond what would be expected based on MQ, a widely used measure of general memory function. Boundary-based and landmark-based spatial recall were both strongly related to bilateral hippocampal volumes, but not to volumes of the thalamus, putamen, pallidum, nucleus accumbens, or caudate nucleus. The results show that boundary-based and landmark-based allocentric spatial recall are similarly impaired in patients with SHD, that both types of recall are impaired beyond that predicted by MQ, and that recall deficits are best explained by a reduction in bilateral hippocampal volumes. In humans, bilateral hippocampal atrophy can lead to profound impairments in episodic memory. Across species, perhaps the most well-established contribution of the hippocampus to memory is not to episodic memory generally but to allocentric spatial memory. However, the extent to which navigational spatial memory depends on hippocampal integrity in humans is

  12. Sex differences in spatial navigation and perception in human adolescents and emerging adults

    PubMed Central

    Sneider, Jennifer Tropp; Hamilton, Derek A.; Cohen-Gilbert, Julia E.; Crowley, David J.; Rosso, Isabelle M.; Silveri, Marisa M.

    2014-01-01

    Males typically outperform females on spatial tasks, beginning early in life and continuing into adulthood. This study aimed to characterize age and sex differences in human spatial ability using a virtual Water Maze Task (vWMT), which is based on the classic Morris water maze spatial navigation task used in rodents. Performance on the vWMT and on a task assessing visuospatial perception, Mental Rotations Test (MRT), was examined in 33 adolescents and 39 emerging adults. For the vWMT, significant effects of age and sex were observed for path length in the target region (narrower spatial sampling), and heading error, with emerging adults performing better than adolescents, and an overall male advantage. For the MRT, males scored higher than females, but only in emerging adulthood. Overall, sex differences in visuospatial perception (MRT) emerge differently from those observed on a classic navigation task, with age and sex-specific superior vWMT performance likely related to the use of more efficient strategies. Importantly, these results extend the developmental timeline of spatial ability characterization to include adolescent males and females performing a virtual version of the classic vWMT. PMID:25464337

  13. Apnea-induced rapid eye movement sleep disruption impairs human spatial navigational memory.

    PubMed

    Varga, Andrew W; Kishi, Akifumi; Mantua, Janna; Lim, Jason; Koushyk, Viachaslau; Leibert, David P; Osorio, Ricardo S; Rapoport, David M; Ayappa, Indu

    2014-10-29

    Hippocampal electrophysiology and behavioral evidence support a role for sleep in spatial navigational memory, but the role of particular sleep stages is less clear. Although rodent models suggest the importance of rapid eye movement (REM) sleep in spatial navigational memory, a similar role for REM sleep has never been examined in humans. We recruited subjects with severe obstructive sleep apnea (OSA) who were well treated and adherent with continuous positive airway pressure (CPAP). Restricting CPAP withdrawal to REM through real-time monitoring of the polysomnogram provides a novel way of addressing the role of REM sleep in spatial navigational memory with a physiologically relevant stimulus. Individuals spent two different nights in the laboratory, during which subjects performed timed trials before and after sleep on one of two unique 3D spatial mazes. One night of sleep was normally consolidated with use of therapeutic CPAP throughout, whereas on the other night, CPAP was reduced only in REM sleep, allowing REM OSA to recur. REM disruption via this method caused REM sleep reduction and significantly fragmented any remaining REM sleep without affecting total sleep time, sleep efficiency, or slow-wave sleep. We observed improvements in maze performance after a night of normal sleep that were significantly attenuated after a night of REM disruption without changes in psychomotor vigilance. Furthermore, the improvement in maze completion time significantly positively correlated with the mean REM run duration across both sleep conditions. In conclusion, we demonstrate a novel role for REM sleep in human memory formation and highlight a significant cognitive consequence of OSA. Copyright © 2014 the authors 0270-6474/14/3414571-07$15.00/0.

  14. Apnea-Induced Rapid Eye Movement Sleep Disruption Impairs Human Spatial Navigational Memory

    PubMed Central

    Kishi, Akifumi; Mantua, Janna; Lim, Jason; Koushyk, Viachaslau; Leibert, David P.; Osorio, Ricardo S.; Rapoport, David M.; Ayappa, Indu

    2014-01-01

    Hippocampal electrophysiology and behavioral evidence support a role for sleep in spatial navigational memory, but the role of particular sleep stages is less clear. Although rodent models suggest the importance of rapid eye movement (REM) sleep in spatial navigational memory, a similar role for REM sleep has never been examined in humans. We recruited subjects with severe obstructive sleep apnea (OSA) who were well treated and adherent with continuous positive airway pressure (CPAP). Restricting CPAP withdrawal to REM through real-time monitoring of the polysomnogram provides a novel way of addressing the role of REM sleep in spatial navigational memory with a physiologically relevant stimulus. Individuals spent two different nights in the laboratory, during which subjects performed timed trials before and after sleep on one of two unique 3D spatial mazes. One night of sleep was normally consolidated with use of therapeutic CPAP throughout, whereas on the other night, CPAP was reduced only in REM sleep, allowing REM OSA to recur. REM disruption via this method caused REM sleep reduction and significantly fragmented any remaining REM sleep without affecting total sleep time, sleep efficiency, or slow-wave sleep. We observed improvements in maze performance after a night of normal sleep that were significantly attenuated after a night of REM disruption without changes in psychomotor vigilance. Furthermore, the improvement in maze completion time significantly positively correlated with the mean REM run duration across both sleep conditions. In conclusion, we demonstrate a novel role for REM sleep in human memory formation and highlight a significant cognitive consequence of OSA. PMID:25355211

  15. Human hippocampal and parahippocampal theta during goal-directed spatial navigation predicts performance on a virtual Morris water maze.

    PubMed

    Cornwell, Brian R; Johnson, Linda L; Holroyd, Tom; Carver, Frederick W; Grillon, Christian

    2008-06-04

    The hippocampus and parahippocampal cortices exhibit theta oscillations during spatial navigation in animals and humans, and in the former are thought to mediate spatial memory formation. Functional specificity of human hippocampal theta, however, is unclear. Neuromagnetic activity was recorded with a whole-head 275-channel magnetoencephalographic (MEG) system as healthy participants navigated to a hidden platform in a virtual reality Morris water maze. MEG data were analyzed for underlying oscillatory sources in the 4-8 Hz band using a spatial filtering technique (i.e., synthetic aperture magnetometry). Source analyses revealed greater theta activity in the left anterior hippocampus and parahippocampal cortices during goal-directed navigation relative to aimless movements in a sensorimotor control condition. Additional analyses showed that left anterior hippocampal activity was predominantly observed during the first one-half of training, pointing to a role for this region in early learning. Moreover, posterior hippocampal theta was highly correlated with navigation performance, with the former accounting for 76% of the variance of the latter. Our findings suggest human spatial learning is dependent on hippocampal and parahippocampal theta oscillations, extending to humans a significant body of research demonstrating such a pivotal role for hippocampal theta in animal navigation.

  16. Spatial navigation in young versus older adults

    PubMed Central

    Gazova, Ivana; Laczó, Jan; Rubinova, Eva; Mokrisova, Ivana; Hyncicova, Eva; Andel, Ross; Vyhnalek, Martin; Sheardova, Katerina; Coulson, Elizabeth J.; Hort, Jakub

    2013-01-01

    Older age is associated with changes in the brain, including the medial temporal lobe, which may result in mild spatial navigation deficits, especially in allocentric navigation. The aim of the study was to characterize the profile of real-space allocentric (world-centered, hippocampus-dependent) and egocentric (body-centered, parietal lobe dependent) navigation and learning in young vs. older adults, and to assess a possible influence of gender. We recruited healthy participants without cognitive deficits on standard neuropsychological testing, white matter lesions or pronounced hippocampal atrophy: 24 young participants (18–26 years old) and 44 older participants stratified as participants 60–70 years old (n = 24) and participants 71–84 years old (n = 20). All underwent spatial navigation testing in the real-space human analog of the Morris Water Maze, which has the advantage of assessing separately allocentric and egocentric navigation and learning. Of the eight consecutive trials, trials 2–8 were used to reduce bias by a rebound effect (more dramatic changes in performance between trials 1 and 2 relative to subsequent trials). The participants who were 71–84 years old (p < 0.001), but not those 60–70 years old, showed deficits in allocentric navigation compared to the young participants. There were no differences in egocentric navigation. All three groups showed spatial learning effect (p’ s ≤ 0.01). There were no gender differences in spatial navigation and learning. Linear regression limited to older participants showed linear (β = 0.30, p = 0.045) and quadratic (β = 0.30, p = 0.046) effect of age on allocentric navigation. There was no effect of age on egocentric navigation. These results demonstrate that navigation deficits in older age may be limited to allocentric navigation, whereas egocentric navigation and learning may remain preserved. This specific pattern of spatial navigation impairment may help differentiate normal aging from

  17. The functional role of human right hippocampal/parahippocampal theta rhythm in environmental encoding during virtual spatial navigation.

    PubMed

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

    2017-03-01

    Low frequency theta band oscillations (4-8 Hz) are thought to provide a timing mechanism for hippocampal place cell firing and to mediate the formation of spatial memory. In rodents, hippocampal theta has been shown to play an important role in encoding a new environment during spatial navigation, but a similar functional role of hippocampal theta in humans has not been firmly established. To investigate this question, we recorded healthy participants' brain responses with a 160-channel whole-head MEG system as they performed two training sets of a virtual Morris water maze task. Environment layouts (except for platform locations) of the two sets were kept constant to measure theta activity during spatial learning in new and familiar environments. In line with previous findings, left hippocampal/parahippocampal theta showed more activation navigating to a hidden platform relative to random swimming. Consistent with our hypothesis, right hippocampal/parahippocampal theta was stronger during the first training set compared to the second one. Notably, theta in this region during the first training set correlated with spatial navigation performance across individuals in both training sets. These results strongly argue for the functional importance of right hippocampal theta in initial encoding of configural properties of an environment during spatial navigation. Our findings provide important evidence that right hippocampal/parahippocampal theta activity is associated with environmental encoding in the human brain. Hum Brain Mapp 38:1347-1361, 2017. © 2016 Wiley Periodicals, Inc.

  18. Interacting networks of brain regions underlie human spatial navigation: A review and novel synthesis of the literature.

    PubMed

    Ekstrom, Arne D; Huffman, Derek J; Starrett, Michael

    2017-09-20

    Navigation is an inherently dynamic and multimodal process, making isolation of the unique cognitive components underlying it challenging. The assumptions of much of the literature on human spatial navigation are that: 1) spatial navigation involves modality independent, discrete metric representations (i.e., egocentric vs. allocentric) 2) such representations can be further distilled to elemental cognitive processes 3) these cognitive processes can be ascribed to unique brain regions. Here, we argue that modality independent spatial representations, instead of providing exact metrics about our surrounding environment, more often involve heuristics for estimating spatial topology useful to the current task at hand. We also argue that egocentric (body-centered) and allocentric (world-centered) representations are better conceptualized as involving a continuum rather than as discrete. We propose a neural model to accommodate these ideas, arguing that such representations also involve a continuum of network interactions centered on retrosplenial and posterior parietal cortex, respectively. Our model thus helps explain both behavioral and neural findings otherwise difficult to account for with classic models of spatial navigation and memory, providing a testable framework for novel experiments. Copyright © 2017, Journal of Neurophysiology.

  19. Effects of Aging on Slow Wave Sleep Dynamics and Human Spatial Navigational Memory Consolidation

    PubMed Central

    Varga, Andrew W.; Ducca, Emma L.; Kishi, Akifumi; Fischer, Esther; Parekh, Ankit; Koushyk, Viachaslau; Yau, Po Lai; Gumb, Tyler; Leibert, David P.; Wohlleber, Margaret E.; Burschtin, Omar E.; Convit, Antonio; Rapoport, David M.

    2016-01-01

    The consolidation of spatial navigational memory during sleep is supported by electrophysiological and behavioral evidence. The features of sleep that mediate this ability may change with aging, as percentage of slow wave sleep is canonically thought to decrease with age, and slow waves are thought to help orchestrate hippocampal-neocortical dialogue that supports systems level consolidation. In this study, groups of younger and older subjects performed timed trials before and after polysomnographically recorded sleep on a 3D spatial maze navigational task. Although younger subjects performed better than older subjects at baseline, both groups showed similar improvement across pre-sleep trials. However, younger subjects experienced significant improvement in maze performance during sleep that was not observed in older subjects, without differences in morning psychomotor vigilance between groups. Older subjects had sleep quality marked by decreased amount of slow wave sleep and increased fragmentation of slow wave sleep, resulting in decreased slow wave activity. Across all subjects, frontal slow wave activity was positively correlated with both overnight change in maze performance and medial prefrontal cortical volume, illuminating a potential neuroanatomical substrate for slow wave activity changes with aging and underscoring the importance of slow wave activity in sleep-dependent spatial navigational memory consolidation. PMID:27143431

  20. Direct and indirect parieto-medial temporal pathways for spatial navigation in humans: evidence from resting-state functional connectivity.

    PubMed

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

    2017-05-01

    Anatomical and functional findings in primates suggest the existence of a dedicated parieto-medial temporal pathway for spatial navigation, consisting of both direct and indirect projections from the caudal inferior parietal lobe (cIPL) to the hippocampus and the parahippocampal cortex, with indirect projections relaying through the posterior cingulate and retrosplenial cortex. This neural network is largely unexplored in humans. This study aimed at testing the existence of a parieto-medial temporal pathway for spatial navigation in humans. We explored the cortical connectivity patterns of the parahippocampal place area (PPA), the retrosplenial cortex (RSC), and the hippocampus (HC) using resting-state functional connectivity MRI. Our results demonstrate the existence of connections between the medial temporal lobe structures, i.e., PPA and HC, and the angular gyrus (AG), the human homologue of cIPL, as well as between RSC and AG. These connectivity patterns seem to reflect the direct and the indirect projections found in primates from cIPL to the medial temporal lobe. Such a result deserves feasible considerations to better understand the brain networks underpinning human spatial navigation.

  1. Hippocampal theta oscillations are slower in humans than in rodents: implications for models of spatial navigation and memory.

    PubMed

    Jacobs, Joshua

    2014-02-05

    The theta oscillation is a neuroscience enigma. When a rat runs through an environment, large-amplitude theta oscillations (4-10 Hz) reliably appear in the hippocampus's electrical activity. The consistency of this pattern led to theta playing a central role in theories on the neural basis of mammalian spatial navigation and memory. However, in fact, hippocampal oscillations at 4-10 Hz are rare in humans and in some other species. This presents a challenge for theories proposing theta as an essential component of the mammalian brain, including models of place and grid cells. Here, I examine this issue by reviewing recent research on human hippocampal oscillations using direct brain recordings from neurosurgical patients. This work indicates that the human hippocampus does indeed exhibit rhythms that are functionally similar to theta oscillations found in rodents, but that these signals have a slower frequency of approximately 1-4 Hz. I argue that oscillatory models of navigation and memory derived from rodent data are relevant for humans, but that they should be modified to account for the slower frequency of the human theta rhythm.

  2. Hippocampal theta oscillations are slower in humans than in rodents: implications for models of spatial navigation and memory

    PubMed Central

    Jacobs, Joshua

    2014-01-01

    The theta oscillation is a neuroscience enigma. When a rat runs through an environment, large-amplitude theta oscillations (4–10 Hz) reliably appear in the hippocampus's electrical activity. The consistency of this pattern led to theta playing a central role in theories on the neural basis of mammalian spatial navigation and memory. However, in fact, hippocampal oscillations at 4–10 Hz are rare in humans and in some other species. This presents a challenge for theories proposing theta as an essential component of the mammalian brain, including models of place and grid cells. Here, I examine this issue by reviewing recent research on human hippocampal oscillations using direct brain recordings from neurosurgical patients. This work indicates that the human hippocampus does indeed exhibit rhythms that are functionally similar to theta oscillations found in rodents, but that these signals have a slower frequency of approximately 1–4 Hz. I argue that oscillatory models of navigation and memory derived from rodent data are relevant for humans, but that they should be modified to account for the slower frequency of the human theta rhythm. PMID:24366145

  3. The Shape of Human Navigation: How Environmental Geometry Is Used in Maintenance of Spatial Orientation

    ERIC Educational Resources Information Center

    Kelly, Jonathan W.; McNamara, Timothy P.; Bodenheimer, Bobby; Carr, Thomas H.; Rieser, John J.

    2008-01-01

    The role of environmental geometry in maintaining spatial orientation was measured in immersive virtual reality using a spatial updating task (requiring maintenance of orientation during locomotion) within rooms varying in rotational symmetry (the number of room orientations providing the same perspective). Spatial updating was equally good in…

  4. The Shape of Human Navigation: How Environmental Geometry Is Used in Maintenance of Spatial Orientation

    ERIC Educational Resources Information Center

    Kelly, Jonathan W.; McNamara, Timothy P.; Bodenheimer, Bobby; Carr, Thomas H.; Rieser, John J.

    2008-01-01

    The role of environmental geometry in maintaining spatial orientation was measured in immersive virtual reality using a spatial updating task (requiring maintenance of orientation during locomotion) within rooms varying in rotational symmetry (the number of room orientations providing the same perspective). Spatial updating was equally good in…

  5. Role of low- and high-frequency oscillations in the human hippocampus for encoding environmental novelty during a spatial navigation task.

    PubMed

    Park, Jinsick; Lee, Hojong; Kim, Taekyung; Park, Ga Young; Lee, Eun Mi; Baek, Seunghee; Ku, Jeonghun; Kim, In Young; Kim, Sun I; Jang, Dong Pyo; Kang, Joong Koo

    2014-11-01

    The hippocampus plays a key role in the encoding and retrieval of information related to novel environments during spatial navigation. However, the neural basis for these processes in the human hippocampus remains unknown because it is difficult to directly measure neural signals in the human hippocampus. This study investigated hippocampal neural oscillations involved in encoding novel environments during spatial navigation in a virtual environment. Seven epileptic patients with implanted intracranial hippocampal depth electrodes performed three sessions of virtual environment navigation. Each session consisted of a navigation task and a location-recall task. The navigation task consisted of eight blocks, and in each block, the participant navigated to the location of four different objects and was instructed to remember the location of the objects. After the eight blocks were completed, a location-recall task was performed for each of the four objects. Intracranial electroencephalography data were monitored during the navigation tasks. Theta (5-8 Hz) and delta (1-4 Hz) oscillations were lower in the first block (novel environment) than in the eighth block (familiar environment) of the navigation task, and significantly increased from block one to block eight. By contrast, low-gamma (31-50 Hz) oscillations were higher in the first block than in the eighth block of the navigation task, and significantly decreased from block one to block eight. Comparison of sessions with high recall performance (low error between identified and actual object location) and low recall performance revealed that high-gamma (51-100 Hz) oscillations significantly decreased from block one to block eight only in sessions with high recall performance. These findings suggest that delta, theta, and low-gamma oscillations were associated with encoding of environmental novelty and high-gamma oscillations were important for the successful encoding of environmental novelty.

  6. Active and Passive Spatial Learning in Human Navigation: Acquisition of Survey Knowledge

    ERIC Educational Resources Information Center

    Chrastil, Elizabeth R.; Warren, William H.

    2013-01-01

    It seems intuitively obvious that active exploration of a new environment would lead to better spatial learning than would passive visual exposure. It is unclear, however, which components of active learning contribute to spatial knowledge, and previous literature is decidedly mixed. This experiment tests the contributions of 4 components to…

  7. Active and Passive Spatial Learning in Human Navigation: Acquisition of Graph Knowledge

    ERIC Educational Resources Information Center

    Chrastil, Elizabeth R.; Warren, William H.

    2015-01-01

    It is known that active exploration of a new environment leads to better spatial learning than does passive visual exposure. We ask whether specific components of active learning differentially contribute to particular forms of spatial knowledge--the "exploration-specific learning hypothesis". Previously, we found that idiothetic…

  8. Active and Passive Spatial Learning in Human Navigation: Acquisition of Survey Knowledge

    ERIC Educational Resources Information Center

    Chrastil, Elizabeth R.; Warren, William H.

    2013-01-01

    It seems intuitively obvious that active exploration of a new environment would lead to better spatial learning than would passive visual exposure. It is unclear, however, which components of active learning contribute to spatial knowledge, and previous literature is decidedly mixed. This experiment tests the contributions of 4 components to…

  9. Active and Passive Spatial Learning in Human Navigation: Acquisition of Graph Knowledge

    ERIC Educational Resources Information Center

    Chrastil, Elizabeth R.; Warren, William H.

    2015-01-01

    It is known that active exploration of a new environment leads to better spatial learning than does passive visual exposure. We ask whether specific components of active learning differentially contribute to particular forms of spatial knowledge--the "exploration-specific learning hypothesis". Previously, we found that idiothetic…

  10. Modified Navigation Instructions for Spatial Navigation Assistance Systems Lead to Incidental Spatial Learning.

    PubMed

    Gramann, Klaus; Hoepner, Paul; Karrer-Gauss, Katja

    2017-01-01

    Spatial cognitive skills deteriorate with the increasing use of automated GPS navigation and a general decrease in the ability to orient in space might have further impact on independence, autonomy, and quality of life. In the present study we investigate whether modified navigation instructions support incidental spatial knowledge acquisition. A virtual driving environment was used to examine the impact of modified navigation instructions on spatial learning while using a GPS navigation assistance system. Participants navigated through a simulated urban and suburban environment, using navigation support to reach their destination. Driving performance as well as spatial learning was thereby assessed. Three navigation instruction conditions were tested: (i) a control group that was provided with classical navigation instructions at decision points, and two other groups that received navigation instructions at decision points including either (ii) additional irrelevant information about landmarks or (iii) additional personally relevant information (i.e., individual preferences regarding food, hobbies, etc.), associated with landmarks. Driving performance revealed no differences between navigation instructions. Significant improvements were observed in both modified navigation instruction conditions on three different measures of spatial learning and memory: subsequent navigation of the initial route without navigation assistance, landmark recognition, and sketch map drawing. Future navigation assistance systems could incorporate modified instructions to promote incidental spatial learning and to foster more general spatial cognitive abilities. Such systems might extend mobility across the lifespan.

  11. Modified Navigation Instructions for Spatial Navigation Assistance Systems Lead to Incidental Spatial Learning

    PubMed Central

    Gramann, Klaus; Hoepner, Paul; Karrer-Gauss, Katja

    2017-01-01

    Spatial cognitive skills deteriorate with the increasing use of automated GPS navigation and a general decrease in the ability to orient in space might have further impact on independence, autonomy, and quality of life. In the present study we investigate whether modified navigation instructions support incidental spatial knowledge acquisition. A virtual driving environment was used to examine the impact of modified navigation instructions on spatial learning while using a GPS navigation assistance system. Participants navigated through a simulated urban and suburban environment, using navigation support to reach their destination. Driving performance as well as spatial learning was thereby assessed. Three navigation instruction conditions were tested: (i) a control group that was provided with classical navigation instructions at decision points, and two other groups that received navigation instructions at decision points including either (ii) additional irrelevant information about landmarks or (iii) additional personally relevant information (i.e., individual preferences regarding food, hobbies, etc.), associated with landmarks. Driving performance revealed no differences between navigation instructions. Significant improvements were observed in both modified navigation instruction conditions on three different measures of spatial learning and memory: subsequent navigation of the initial route without navigation assistance, landmark recognition, and sketch map drawing. Future navigation assistance systems could incorporate modified instructions to promote incidental spatial learning and to foster more general spatial cognitive abilities. Such systems might extend mobility across the lifespan. PMID:28243219

  12. Spatial navigation using night vision goggles

    NASA Astrophysics Data System (ADS)

    Gauthier, Michelle; Parush, Avi; Macuda, Todd; Tang, Denis; Craig, Greg; Jennings, Sion

    2006-05-01

    While anecdotal reports suggest that Night Vision Goggles influence spatial navigation and wayfinding (Braithwaite, Douglass, Durnford, and Lucas, 1998), few studies have systematically characterized the nature of these effects. To address this issue, the current study examined the impact of NVGs on navigation and wayfinding performance. One group of participants were required to navigate a walking maze and retrieve target objects while wearing NVGs (experimental condition), while a second control group navigated the maze without NVGs. We measured several performance metrics of navigation and wayfinding. Our results show that navigation and wayfinding with NVGs (experimental group) appeared to be harder, with longer navigation durations and more navigational errors compared to not using NVGs (control group). However, a significant decrease in navigation duration over the course of the wayfinding trials occurred earlier with NVGs, in addition to significant decreases in navigational steps compared to the control group. These results support the notion that NVGs directly affect spatial navigation and wayfinding performance. These degradations in performance should be considered in operational planning and NVG training programs. Further research is necessary to expand our understanding of the impact of NVGs on spatial cognition.

  13. Active and passive spatial learning in human navigation: acquisition of graph knowledge.

    PubMed

    Chrastil, Elizabeth R; Warren, William H

    2015-07-01

    It is known that active exploration of a new environment leads to better spatial learning than does passive visual exposure. We ask whether specific components of active learning differentially contribute to particular forms of spatial knowledge-the exploration-specific learning hypothesis. Previously, we found that idiothetic information during walking is the primary active contributor to metric survey knowledge (Chrastil & Warren, 2013). In this study, we test the contributions of 3 components to topological graph and route knowledge: visual information, idiothetic information, and cognitive decision making. Four groups of participants learned the locations of 8 objects in a virtual hedge maze by (a) walking or (b) watching a video, crossed with (1) either making decisions about their path or (2) being guided through the maze. Route and graph knowledge were assessed by walking in the maze corridors from a starting object to the remembered location of a test object, with frequent detours. Decision making during exploration significantly contributed to subsequent route finding in the walking condition, whereas idiothetic information did not. Participants took novel routes and the metrically shortest routes on the majority of both direct and barrier trials, indicating that labeled graph knowledge-not merely route knowledge-was acquired. We conclude that, consistent with the exploration-specific learning hypothesis, decision making is the primary component of active learning for the acquisition of topological graph knowledge, whereas idiothetic information is the primary component for metric survey knowledge. (c) 2015 APA, all rights reserved.

  14. Active and passive spatial learning in human navigation: acquisition of survey knowledge.

    PubMed

    Chrastil, Elizabeth R; Warren, William H

    2013-09-01

    It seems intuitively obvious that active exploration of a new environment would lead to better spatial learning than would passive visual exposure. It is unclear, however, which components of active learning contribute to spatial knowledge, and previous literature is decidedly mixed. This experiment tests the contributions of 4 components to metric survey knowledge: visual, vestibular, and podokinetic information and cognitive decision making. In the learning phase, 6 groups of participants learned the locations of 8 objects in a virtual hedge maze by (a) walking, (b) being pushed in a wheelchair, or (c) watching a video, crossed with (1) making decisions about their path or (2) being guided through the maze. In the test phase, survey knowledge was assessed by having participants walk a novel shortcut from a starting object to the remembered location of a test object, with the maze removed. Performance was slightly better than chance in the passive video condition. The addition of vestibular information did not improve performance in the wheelchair condition, but the addition of podokinetic information significantly improved angular accuracy in the walking condition. In contrast, there was no effect of decision making in any condition. The results indicate that visual and podokinetic information significantly contribute to survey knowledge, whereas vestibular information and decision making do not. We conclude that podokinetic information is the primary component of active learning for the acquisition of metric survey knowledge. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  15. Spatial Database Modeling for Indoor Navigation Systems

    NASA Astrophysics Data System (ADS)

    Gotlib, Dariusz; Gnat, Miłosz

    2013-12-01

    For many years, cartographers are involved in designing GIS and navigation systems. Most GIS applications use the outdoor data. Increasingly, similar applications are used inside buildings. Therefore it is important to find the proper model of indoor spatial database. The development of indoor navigation systems should utilize advanced teleinformation, geoinformatics, geodetic and cartographical knowledge. The authors present the fundamental requirements for the indoor data model for navigation purposes. Presenting some of the solutions adopted in the world they emphasize that navigation applications require specific data to present the navigation routes in the right way. There is presented original solution for indoor data model created by authors on the basis of BISDM model. Its purpose is to expand the opportunities for use in indoor navigation.

  16. Spatial abstraction for autonomous robot navigation.

    PubMed

    Epstein, Susan L; Aroor, Anoop; Evanusa, Matthew; Sklar, Elizabeth I; Parsons, Simon

    2015-09-01

    Optimal navigation for a simulated robot relies on a detailed map and explicit path planning, an approach problematic for real-world robots that are subject to noise and error. This paper reports on autonomous robots that rely on local spatial perception, learning, and commonsense rationales instead. Despite realistic actuator error, learned spatial abstractions form a model that supports effective travel.

  17. Two Systems of Spatial Representation Underlying Navigation

    PubMed Central

    Lee, Sang Ah; Spelke, Elizabeth S.

    2011-01-01

    We review evidence for two distinct cognitive processes by which humans and animals represent the navigable environment. One process uses the shape of the extended 3D surface layout to specify the navigator’s position and orientation. A second process uses objects and patterns as beacons to specify the locations of significant objects. Although much of the evidence for these processes comes from neurophysiological studies of navigating animals and neuroimaging studies of human adults, behavioral studies of navigating children shed light both on the nature of these systems and on their interactions. PMID:20614214

  18. Spatial Navigation in Preclinical Alzheimer's Disease.

    PubMed

    Allison, Samantha L; Fagan, Anne M; Morris, John C; Head, Denise

    2016-02-09

    Although several previous studies have demonstrated navigational deficits in early-stage symptomatic Alzheimer's disease (AD), navigational abilities in preclinical AD have not been examined. The present investigation examined the effects of preclinical AD and early-stage symptomatic AD on spatial navigation performance. Performance on tasks of wayfinding and route learning in a virtual reality environment were examined. Comparisons were made across the following three groups: Clinically normal without preclinical AD (n = 42), clinically normal with preclinical AD (n = 13), and early-stage symptomatic AD (n = 16) groups. Preclinical AD was defined based on cerebrospinal fluid Aβ42 levels below 500 pg/ml. Preclinical AD was associated with deficits in the use of a wayfinding strategy, but not a route learning strategy. Moreover, post-hoc analyses indicated that wayfinding performance had moderate sensitivity and specificity. Results also confirmed early-stage symptomatic AD-related deficits in the use of both wayfinding and route learning strategies. The results of this study suggest that aspects of spatial navigation may be particularly sensitive at detecting the earliest cognitive deficits of AD.

  19. 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.

  20. 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

  1. Reference frames in virtual spatial navigation are viewpoint dependent

    PubMed Central

    Török, Ágoston; Nguyen, T. Peter; Kolozsvári, Orsolya; Buchanan, Robert J.; Nadasdy, Zoltan

    2014-01-01

    Spatial navigation in the mammalian brain relies on a cognitive map of the environment. Such cognitive maps enable us, for example, to take the optimal route from a given location to a known target. The formation of these maps is naturally influenced by our perception of the environment, meaning it is dependent on factors such as our viewpoint and choice of reference frame. Yet, it is unknown how these factors influence the construction of cognitive maps. Here, we evaluated how various combinations of viewpoints and reference frames affect subjects' performance when they navigated in a bounded virtual environment without landmarks. We measured both their path length and time efficiency and found that (1) ground perspective was associated with egocentric frame of reference, (2) aerial perspective was associated with allocentric frame of reference, (3) there was no appreciable performance difference between first and third person egocentric viewing positions and (4) while none of these effects were dependent on gender, males tended to perform better in general. Our study provides evidence that there are inherent associations between visual perspectives and cognitive reference frames. This result has implications about the mechanisms of path integration in the human brain and may also inspire designs of virtual reality applications. Lastly, we demonstrated the effective use of a tablet PC and spatial navigation tasks for studying spatial and cognitive aspects of human memory. PMID:25249956

  2. Olfactory Orientation and Navigation in Humans

    PubMed Central

    Jacobs, Lucia F.; Arter, Jennifer; Cook, Amy; Sulloway, Frank J.

    2015-01-01

    Although predicted by theory, there is no direct evidence that an animal can define an arbitrary location in space as a coordinate location on an odor grid. Here we show that humans can do so. Using a spatial match-to-sample procedure, humans were led to a random location within a room diffused with two odors. After brief sampling and spatial disorientation, they had to return to this location. Over three conditions, participants had access to different sensory stimuli: olfactory only, visual only, and a final control condition with no olfactory, visual, or auditory stimuli. Humans located the target with higher accuracy in the olfaction-only condition than in the control condition and showed higher accuracy than chance. Thus a mechanism long proposed for the homing pigeon, the ability to define a location on a map constructed from chemical stimuli, may also be a navigational mechanism used by humans. PMID:26083337

  3. Spatial linear navigation: is vision necessary?

    PubMed

    Israël, I; Capelli, A; Priot, A-E; Giannopulu, I

    2013-10-25

    In order to analyze spatial linear navigation through a task of self-controlled reproduction, healthy participants were passively transported on a mobile robot at constant velocity, and then had to reproduce the imposed distance of 2-8m in two conditions: "with vision" and "without vision". Our hypothesis was that the reproduction of distances would be longer with than without visual information. Indeed, with visual information the reproduction of all distances was overshot. In the "without vision" condition the reproduced distances were quite close to the imposed ones, but only for the shortest distances (2 and 4m) as the longest ones were clearly undershot. With vision the reproduction error was less than 10% for all distances; however the error could be smaller without vision at short distances, and therefore vision was not necessary.

  4. Challenges for identifying the neural mechanisms that support spatial navigation: the impact of spatial scale

    PubMed Central

    Wolbers, Thomas; Wiener, Jan M.

    2014-01-01

    Spatial navigation is a fascinating behavior that is essential for our everyday lives. It involves nearly all sensory systems, it requires numerous parallel computations, and it engages multiple memory systems. One of the key problems in this field pertains to the question of reference frames: spatial information such as direction or distance can be coded egocentrically—relative to an observer—or allocentrically—in a reference frame independent of the observer. While many studies have associated striatal and parietal circuits with egocentric coding and entorhinal/hippocampal circuits with allocentric coding, this strict dissociation is not in line with a growing body of experimental data. In this review, we discuss some of the problems that can arise when studying the neural mechanisms that are presumed to support different spatial reference frames. We argue that the scale of space in which a navigation task takes place plays a crucial role in determining the processes that are being recruited. This has important implications, particularly for the inferences that can be made from animal studies in small scale space about the neural mechanisms supporting human spatial navigation in large (environmental) spaces. Furthermore, we argue that many of the commonly used tasks to study spatial navigation and the underlying neuronal mechanisms involve different types of reference frames, which can complicate the interpretation of neurophysiological data. PMID:25140139

  5. Switching from Reaching to Navigation: Differential Cognitive Strategies for Spatial Memory in Children and Adults

    ERIC Educational Resources Information Center

    Belmonti, Vittorio; Cioni, Giovanni; Berthoz, Alain

    2015-01-01

    Navigational and reaching spaces are known to involve different cognitive strategies and brain networks, whose development in humans is still debated. In fact, high-level spatial processing, including allocentric location encoding, is already available to very young children, but navigational strategies are not mature until late childhood. The…

  6. Switching from Reaching to Navigation: Differential Cognitive Strategies for Spatial Memory in Children and Adults

    ERIC Educational Resources Information Center

    Belmonti, Vittorio; Cioni, Giovanni; Berthoz, Alain

    2015-01-01

    Navigational and reaching spaces are known to involve different cognitive strategies and brain networks, whose development in humans is still debated. In fact, high-level spatial processing, including allocentric location encoding, is already available to very young children, but navigational strategies are not mature until late childhood. The…

  7. Human navigation network: the intrinsic functional organization and behavioral relevance.

    PubMed

    Kong, Xiang-Zhen; Wang, Xu; Pu, Yi; Huang, Lijie; Hao, Xin; Zhen, Zonglei; Liu, Jia

    2017-03-01

    Spatial navigation is a crucial ability for living. Previous work has revealed multiple distributed brain regions associated with human navigation. However, little is known about how these regions work together as a network (referred to as navigation network) to support flexible navigation. In a novel protocol, we combined neuroimaging meta-analysis, and functional connectivity and behavioral data from the same subjects. Briefly, we first constructed the navigation network for each participant, by combining a large-scale neuroimaging meta-analysis (with the Neurosynth) and resting-state functional magnetic resonance imaging. Then, we investigated multiple topological properties of the navigation networks, including small-worldness, modularity, and highly connected hubs. Finally, we explored the behavioral relevance of these intrinsic properties in a large sample of healthy young adults (N = 190). We found that navigation networks showed small-world and modular organization at global level. More importantly, we found that increased small-worldness and modularity of the navigation network were associated with better navigation ability. Finally, we found that the right retrosplenial complex (RSC) acted as one of the hubs in the navigation network, and that higher betweenness of this region correlated with better navigation ability, suggesting a critical role of the RSC in modulating the navigation network in human brain. Our study takes one of the first steps toward understanding the underlying organization of the navigation network. Moreover, these findings suggest the potential applications of the novel approach to investigating functionally meaningful networks in human brain and their relations to the behavioral impairments in the aging and psychiatric patients.

  8. Development of cue integration in human navigation.

    PubMed

    Nardini, Marko; Jones, Peter; Bedford, Rachael; Braddick, Oliver

    2008-05-06

    Mammalian navigation depends both on visual landmarks and on self-generated (e.g., vestibular and proprioceptive) cues that signal the organism's own movement [1-5]. When these conflict, landmarks can either reset estimates of self-motion or be integrated with them [6-9]. We asked how humans combine these information sources and whether children, who use both from a young age [10-12], combine them as adults do. Participants attempted to return an object to its original place in an arena when given either visual landmarks only, nonvisual self-motion information only, or both. Adults, but not 4- to 5-year-olds or 7- to 8-year-olds, reduced their response variance when both information sources were available. In an additional "conflict" condition that measured relative reliance on landmarks and self-motion, we predicted behavior under two models: integration (weighted averaging) of the cues and alternation between them. Adults' behavior was predicted by integration, in which the cues were weighted nearly optimally to reduce variance, whereas children's behavior was predicted by alternation. These results suggest that development of individual spatial-representational systems precedes development of the capacity to combine these within a common reference frame. Humans can integrate spatial cues nearly optimally to navigate, but this ability depends on an extended developmental process.

  9. Neurodevelopmental aspects of spatial navigation: a virtual reality fMRI study.

    PubMed

    Pine, Daniel S; Grun, Joseph; Maguire, Eleanor A; Burgess, Neil; Zarahn, Eric; Koda, Vivian; Fyer, Abby; Szeszko, Philip R; Bilder, Robert M

    2002-02-01

    Navigation in spatial contexts has been studied in diverse species, yielding insights into underlying neural mechanisms and their phylogenetic progression. Spatial navigation in humans is marked by age-related changes that may carry important implications for understanding cortical development. The emergence of "allocentric" processing, reflecting that ability to use viewer-independent spatial abstractions, represents an important developmental change. We used fMRI to map brain regions engaged during memory-guided navigation in a virtual reality environment in adolescents and adults. Blood oxygen level-dependent (BOLD) signal was monitored in eight adolescents and eight adults in a 1.5-T MRI scanner during three conditions: (1) memory-guided navigation (NAV); (2) arrow-guided navigation (ARROW); and (3) fixation (FIX). We quantified navigation ability during scanning and allocentric memory after scanning, based on subjects' ability to label a previously unseen, aerial view of the town. Adolescents and adults exhibited similar memory-guided navigation ability, but adults exhibited superior allocentric memory ability. Memory-guided navigation ability during scanning correlated with BOLD change between NAV/ARROWS in various regions, including a right frontal and right-anterior medial temporal lobe region. Age group and allocentric memory together explained significant variance in BOLD change in temporoparietal association cortex and the cerebellum, particularly in the left hemisphere. Consistent with developmental models, these findings relate maturation in the coding of spatial information to functional changes in a distributed, left-lateralized neural network.

  10. Four-Dimensional Spatial Reasoning in Humans

    ERIC Educational Resources Information Center

    Aflalo, T. N.; Graziano, M. S. A.

    2008-01-01

    Human subjects practiced navigation in a virtual, computer-generated maze that contained 4 spatial dimensions rather than the usual 3. The subjects were able to learn the spatial geometry of the 4-dimensional maze as measured by their ability to perform path integration, a standard test of spatial ability. They were able to travel down a winding…

  11. 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.

  12. Visual Landmarks Facilitate Rodent Spatial Navigation in Virtual Reality Environments

    ERIC Educational Resources Information Center

    Youngstrom, Isaac A.; Strowbridge, Ben W.

    2012-01-01

    Because many different sensory modalities contribute to spatial learning in rodents, it has been difficult to determine whether spatial navigation can be guided solely by visual cues. Rodents moving within physical environments with visual cues engage a variety of nonvisual sensory systems that cannot be easily inhibited without lesioning brain…

  13. Visual Landmarks Facilitate Rodent Spatial Navigation in Virtual Reality Environments

    ERIC Educational Resources Information Center

    Youngstrom, Isaac A.; Strowbridge, Ben W.

    2012-01-01

    Because many different sensory modalities contribute to spatial learning in rodents, it has been difficult to determine whether spatial navigation can be guided solely by visual cues. Rodents moving within physical environments with visual cues engage a variety of nonvisual sensory systems that cannot be easily inhibited without lesioning brain…

  14. Persistent and stable biases in spatial learning mechanisms predict navigational style.

    PubMed

    Furman, Andrew J; Clements-Stephens, Amy M; Marchette, Steven A; Shelton, Amy L

    2014-12-01

    A wealth of evidence in rodents and humans supports the central roles of two learning systems--hippocampal place learning and striatal response learning--in the formation of spatial representations to support navigation. Individual differences in the ways that these mechanisms are engaged during initial encoding and subsequent navigation may provide a powerful framework for explaining the wide range of variability found in the strategies and solutions that make up human navigational styles. Previous work has revealed that activation in the hippocampal and striatal networks during learning could predict navigational style. Here, we used functional magnetic resonance imaging to investigate the relative activations in these systems during both initial encoding and the act of dynamic navigation in a learned environment. Participants learned a virtual environment and were tested on subsequent navigation to targets within the environment. We observed that a given individual had a consistent balance of memory system engagement across both initial encoding and subsequent navigation, a balance that successfully predicted the participants' tendencies to use novel shortcuts versus familiar paths during dynamic navigation. This was further supported by the observation that the activation during subsequent retrieval was not dependent on the type of solution used on a given trial. Taken together, our results suggest a model in which the place- and response-learning systems are present in parallel to support a variety of navigational behaviors, but stable biases in the engagement of these systems influence what solutions might be available for any given individual.

  15. The Cognitive Architecture of Spatial Navigation: Hippocampal and Striatal Contributions.

    PubMed

    Chersi, Fabian; Burgess, Neil

    2015-10-07

    Spatial navigation can serve as a model system in cognitive neuroscience, in which specific neural representations, learning rules, and control strategies can be inferred from the vast experimental literature that exists across many species, including humans. Here, we review this literature, focusing on the contributions of hippocampal and striatal systems, and attempt to outline a minimal cognitive architecture that is consistent with the experimental literature and that synthesizes previous related computational modeling. The resulting architecture includes striatal reinforcement learning based on egocentric representations of sensory states and actions, incidental Hebbian association of sensory information with allocentric state representations in the hippocampus, and arbitration of the outputs of both systems based on confidence/uncertainty in medial prefrontal cortex. We discuss the relationship between this architecture and learning in model-free and model-based systems, episodic memory, imagery, and planning, including some open questions and directions for further experiments.

  16. Switching from reaching to navigation: differential cognitive strategies for spatial memory in children and adults.

    PubMed

    Belmonti, Vittorio; Cioni, Giovanni; Berthoz, Alain

    2015-07-01

    Navigational and reaching spaces are known to involve different cognitive strategies and brain networks, whose development in humans is still debated. In fact, high-level spatial processing, including allocentric location encoding, is already available to very young children, but navigational strategies are not mature until late childhood. The Magic Carpet (MC) is a new electronic device translating the traditional Corsi Block-tapping Test (CBT) to navigational space. In this study, the MC and the CBT were used to assess spatial memory for navigation and for reaching, respectively. Our hypothesis was that school-age children would not treat MC stimuli as navigational paths, assimilating them to reaching sequences. Ninety-one healthy children aged 6 to 11 years and 18 adults were enrolled. Overall short-term memory performance (span) on both tests, effects of sequence geometry, and error patterns according to a new classification were studied. Span increased with age on both tests, but relatively more in navigational than in reaching space, particularly in males. Sequence geometry specifically influenced navigation, not reaching. The number of body rotations along the path affected MC performance in children more than in adults, and in women more than in men. Error patterns indicated that navigational sequences were increasingly retained as global paths across development, in contrast to separately stored reaching locations. A sequence of spatial locations can be coded as a navigational path only if a cognitive switch from a reaching mode to a navigation mode occurs. This implies the integration of egocentric and allocentric reference frames, of visual and idiothetic cues, and access to long-term memory. This switch is not yet fulfilled at school age due to immature executive functions.

  17. From Objects to Landmarks: The Function of Visual Location Information in Spatial Navigation

    PubMed Central

    Chan, Edgar; Baumann, Oliver; Bellgrove, Mark A.; Mattingley, Jason B.

    2012-01-01

    Landmarks play an important role in guiding navigational behavior. A host of studies in the last 15 years has demonstrated that environmental objects can act as landmarks for navigation in different ways. In this review, we propose a parsimonious four-part taxonomy for conceptualizing object location information during navigation. We begin by outlining object properties that appear to be important for a landmark to attain salience. We then systematically examine the different functions of objects as navigational landmarks based on previous behavioral and neuroanatomical findings in rodents and humans. Evidence is presented showing that single environmental objects can function as navigational beacons, or act as associative or orientation cues. In addition, we argue that extended surfaces or boundaries can act as landmarks by providing a frame of reference for encoding spatial information. The present review provides a concise taxonomy of the use of visual objects as landmarks in navigation and should serve as a useful reference for future research into landmark-based spatial navigation. PMID:22969737

  18. Segregating cognitive functions within hippocampal formation: a quantitative meta-analysis on spatial navigation and episodic memory.

    PubMed

    Kühn, Simone; Gallinat, Jürgen

    2014-04-01

    The most important cognitive domains where hippocampal formation is crucially involved are navigation and memory. Some evidence suggests that different hippocampal subregions mediate these domains. However, a quantitative meta-analysis on neuroimaging studies of spatial navigation versus memory is lacking. By means of activation likelihood estimation (ALE), we investigate concurrence of brain regions activated during spatial navigation encoding and retrieval as well as during episodic memory encoding and retrieval tasks in humans. During encoding in spatial navigation, activity was located in more posterior regions of the hippocampal formation, whereas episodic memory encoding was located in more anterior regions. Retrieval in spatial navigation was more strongly lateralized to the right compared to episodic memory retrieval. Within studies on spatial navigation retrieval, immediate recall was located more posterior and delayed recall more anterior. Overlap between concurrence of activation in spatial navigation and episodic memory was rather limited in comparison to uniquely involved regions. This argues in favor of two distinct networks, one for spatial navigation the other for episodic memory within the hippocampal formation. Copyright © 2013 Wiley Periodicals, Inc.

  19. Does Spatial Locative Comprehension Predict Landmark-Based Navigation?

    PubMed Central

    Piccardi, Laura; Palermo, Liana; Bocchi, Alessia; Guariglia, Cecilia; D’Amico, Simonetta

    2015-01-01

    In the present study we investigated the role of spatial locative comprehension in learning and retrieving pathways when landmarks were available and when they were absent in a sample of typically developing 6- to 11-year-old children. Our results show that the more proficient children are in understanding spatial locatives the more they are able to learn pathways, retrieve them after a delay and represent them on a map when landmarks are present in the environment. These findings suggest that spatial language is crucial when individuals rely on sequences of landmarks to drive their navigation towards a given goal but that it is not involved when navigational representations based on the geometrical shape of the environment or the coding of body movements are sufficient for memorizing and recalling short pathways. PMID:25629814

  20. Does spatial locative comprehension predict landmark-based navigation?

    PubMed

    Piccardi, Laura; Palermo, Liana; Bocchi, Alessia; Guariglia, Cecilia; D'Amico, Simonetta

    2015-01-01

    In the present study we investigated the role of spatial locative comprehension in learning and retrieving pathways when landmarks were available and when they were absent in a sample of typically developing 6- to 11-year-old children. Our results show that the more proficient children are in understanding spatial locatives the more they are able to learn pathways, retrieve them after a delay and represent them on a map when landmarks are present in the environment. These findings suggest that spatial language is crucial when individuals rely on sequences of landmarks to drive their navigation towards a given goal but that it is not involved when navigational representations based on the geometrical shape of the environment or the coding of body movements are sufficient for memorizing and recalling short pathways.

  1. Impaired Spatial Navigation in Pediatric Anxiety

    ERIC Educational Resources Information Center

    Mueller, Sven C.; Temple, Veronica; Cornwell, Brian; Grillon, Christian; Pine, Daniel S.; Ernst, Monique

    2009-01-01

    Background: Previous theories implicate hippocampal dysfunction in anxiety disorders. Most of the data supporting these theories stem from animal research, particularly lesion studies. The generalization of findings from rodent models to human function is hampered by fundamental inter-species differences. The present work uses a task of spatial…

  2. Prospective representation of navigational goals in the human hippocampus.

    PubMed

    Brown, Thackery I; Carr, Valerie A; LaRocque, Karen F; Favila, Serra E; Gordon, Alan M; Bowles, Ben; Bailenson, Jeremy N; Wagner, Anthony D

    2016-06-10

    Mental representation of the future is a fundamental component of goal-directed behavior. Computational and animal models highlight prospective spatial coding in the hippocampus, mediated by interactions with the prefrontal cortex, as a putative mechanism for simulating future events. Using whole-brain high-resolution functional magnetic resonance imaging and multi-voxel pattern classification, we tested whether the human hippocampus and interrelated cortical structures support prospective representation of navigational goals. Results demonstrated that hippocampal activity patterns code for future goals to which participants subsequently navigate, as well as for intervening locations along the route, consistent with trajectory-specific simulation. The strength of hippocampal goal representations covaried with goal-related coding in the prefrontal, medial temporal, and medial parietal cortex. Collectively, these data indicate that a hippocampal-cortical network supports prospective simulation of navigational events during goal-directed planning.

  3. Visual landmarks facilitate rodent spatial navigation in virtual reality environments

    PubMed Central

    Youngstrom, Isaac A.; Strowbridge, Ben W.

    2012-01-01

    Because many different sensory modalities contribute to spatial learning in rodents, it has been difficult to determine whether spatial navigation can be guided solely by visual cues. Rodents moving within physical environments with visual cues engage a variety of nonvisual sensory systems that cannot be easily inhibited without lesioning brain areas. Virtual reality offers a unique approach to ask whether visual landmark cues alone are sufficient to improve performance in a spatial task. We found that mice could learn to navigate between two water reward locations along a virtual bidirectional linear track using a spherical treadmill. Mice exposed to a virtual environment with vivid visual cues rendered on a single monitor increased their performance over a 3-d training regimen. Training significantly increased the percentage of time avatars controlled by the mice spent near reward locations in probe trials without water rewards. Neither improvement during training or spatial learning for reward locations occurred with mice operating a virtual environment without vivid landmarks or with mice deprived of all visual feedback. Mice operating the vivid environment developed stereotyped avatar turning behaviors when alternating between reward zones that were positively correlated with their performance on the probe trial. These results suggest that mice are able to learn to navigate to specific locations using only visual cues presented within a virtual environment rendered on a single computer monitor. PMID:22345484

  4. Four-dimensional spatial reasoning in humans.

    PubMed

    Aflalo, T N; Graziano, M S A

    2008-10-01

    Human subjects practiced navigation in a virtual, computer-generated maze that contained 4 spatial dimensions rather than the usual 3. The subjects were able to learn the spatial geometry of the 4-dimensional maze as measured by their ability to perform path integration, a standard test of spatial ability. They were able to travel down a winding corridor to its end and then point back accurately toward the occluded origin. One interpretation is that the brain substrate for spatial navigation is not a built-in map of the 3-dimensional world. Instead it may be better described as a set of general rules for manipulating spatial information that can be applied with practice to a diversity of spatial frameworks.

  5. The contribution of virtual reality to the diagnosis of spatial navigation disorders and to the study of the role of navigational aids: A systematic literature review.

    PubMed

    Cogné, M; Taillade, M; N'Kaoua, B; Tarruella, A; Klinger, E; Larrue, F; Sauzéon, H; Joseph, P-A; Sorita, E

    2017-06-01

    Spatial navigation, which involves higher cognitive functions, is frequently implemented in daily activities, and is critical to the participation of human beings in mainstream environments. Virtual reality is an expanding tool, which enables on one hand the assessment of the cognitive functions involved in spatial navigation, and on the other the rehabilitation of patients with spatial navigation difficulties. Topographical disorientation is a frequent deficit among patients suffering from neurological diseases. The use of virtual environments enables the information incorporated into the virtual environment to be manipulated empirically. But the impact of manipulations seems differ according to their nature (quantity, occurrence, and characteristics of the stimuli) and the target population. We performed a systematic review of research on virtual spatial navigation covering the period from 2005 to 2015. We focused first on the contribution of virtual spatial navigation for patients with brain injury or schizophrenia, or in the context of ageing and dementia, and then on the impact of visual or auditory stimuli on virtual spatial navigation. On the basis of 6521 abstracts identified in 2 databases (Pubmed and Scopus) with the keywords « navigation » and « virtual », 1103 abstracts were selected by adding the keywords "ageing", "dementia", "brain injury", "stroke", "schizophrenia", "aid", "help", "stimulus" and "cue"; Among these, 63 articles were included in the present qualitative analysis. Unlike pencil-and-paper tests, virtual reality is useful to assess large-scale navigation strategies in patients with brain injury or schizophrenia, or in the context of ageing and dementia. Better knowledge about both the impact of the different aids and the cognitive processes involved is essential for the use of aids in neurorehabilitation. Copyright © 2016. Published by Elsevier Masson SAS.

  6. Spatial Navigation Strategies in Peromyscus: a Comparative Study

    PubMed Central

    Jašarević, Eldin; Williams, Scott A.; Roberts, R. Michael; Geary, David C.; Rosenfeld, Cheryl S.

    2012-01-01

    A male advantage in spatial abilities is predicted to evolve in species where males rely on expansion of home territory to locate dispersed mates during the breeding season. We sought to examine mechanistic underpinnings of this evolved trait by comparing spatial navigational abilities in two species of Peromyscus that employ widely different reproductive strategies. Males and females from outbred stocks of deer mice (P. maniculatus bairdii) in which males engage in territorial expansion and mate search and California mice (P. californicus insignis), in which males do not, were administered tasks that assessed spatial learning and memory, and activity and exploratory behaviours. The maze employed for these studies included four spatial cues that could be used to aid in locating 1 of 12 potential escape holes. As predicted, male deer mice outperformed conspecific females and California mice males in maze performance and memory, and this difference appeared to be due to extent to which animals used spatial cues to guide maze navigation. Consistent with territorial expansion as a component of competition for mates, male deer mice were more active and engaged in more exploratory and less anxiety-related behaviours than conspecific females and California mice males. The results have implications for understanding and studying the cognitive and behavioural mechanisms that have evolved through male-male competition that involves territorial expansion and mate search. PMID:23355748

  7. Structural and functional neural correlates of spatial navigation: a combined voxel-based morphometry and functional connectivity study.

    PubMed

    Hao, Xin; Huang, Yi; Li, Xueting; Song, Yiying; Kong, Xiangzhen; Wang, Xu; Yang, Zetian; Zhen, Zonglei; Liu, Jia

    2016-12-01

    Navigation is a fundamental and multidimensional cognitive function that individuals rely on to move around the environment. In this study, we investigated the neural basis of human spatial navigation ability. A large cohort of participants (N > 200) was examined on their navigation ability behaviorally and structural and functional magnetic resonance imaging (MRI) were then used to explore the corresponding neural basis of spatial navigation. The gray matter volume (GMV) of the bilateral parahippocampus (PHG), retrosplenial complex (RSC), entorhinal cortex (EC), hippocampus (HPC), and thalamus (THAL) was correlated with the participants' self-reported navigational ability in general, and their sense of direction in particular. Further fMRI studies showed that the PHG, RSC, and EC selectively responded to visually presented scenes, whereas the HPC and THAL showed no selectivity, suggesting a functional division of labor among these regions in spatial navigation. The resting-state functional connectivity analysis further revealed a hierarchical neural network for navigation constituted by these regions, which can be further categorized into three relatively independent components (i.e., scene recognition component, cognitive map component, and the component of heading direction for locomotion, respectively). Our study combined multi-modality imaging data to illustrate that multiple brain regions may work collaboratively to extract, integrate, store, and orientate spatial information to guide navigation behaviors.

  8. Robotic Navigation Emulating Human Performance

    DTIC Science & Technology

    2012-03-10

    Natural and virtual scenes: human recovery of the shape of a 3D scene. Journal of Vision, 11(11): 72 (VSS Abstract). Latecki, L.J., Lu, C., Sobel... Journal of Computer vision, 9, 113-136. Li, Y. (2009). Perception of Parallelepipeds: Perkins’ Law. Perception, 38, 1767-1781. Li, Y. & Pizlo, Z. (2011...T., Shi, Y., Kwon, T. & Pizlo, Z. (2011) A Bayesian model of binocular perception of 3D mirror symmetrical polyhedral. Journal of Vision, 11(4):11

  9. Decoding the view expectation during learned maze navigation from human fronto-parietal network.

    PubMed

    Shikauchi, Yumi; Ishii, Shin

    2015-12-03

    Humans use external cues and prior knowledge about the environment to monitor their positions during spatial navigation. View expectation is essential for correlating scene views with a cognitive map. To determine how the brain performs view expectation during spatial navigation, we applied a multiple parallel decoding technique to functional magnetic resonance imaging (fMRI) when human participants performed scene choice tasks in learned maze navigation environments. We decoded participants' view expectation from fMRI signals in parietal and medial prefrontal cortices, whereas activity patterns in occipital cortex represented various types of external cues. The decoder's output reflected participants' expectations even when they were wrong, corresponding to subjective beliefs opposed to objective reality. Thus, view expectation is subjectively represented in human brain, and the fronto-parietal network is involved in integrating external cues and prior knowledge during spatial navigation.

  10. Decoding the view expectation during learned maze navigation from human fronto-parietal network

    PubMed Central

    Shikauchi, Yumi; Ishii, Shin

    2015-01-01

    Humans use external cues and prior knowledge about the environment to monitor their positions during spatial navigation. View expectation is essential for correlating scene views with a cognitive map. To determine how the brain performs view expectation during spatial navigation, we applied a multiple parallel decoding technique to functional magnetic resonance imaging (fMRI) when human participants performed scene choice tasks in learned maze navigation environments. We decoded participants’ view expectation from fMRI signals in parietal and medial prefrontal cortices, whereas activity patterns in occipital cortex represented various types of external cues. The decoder’s output reflected participants’ expectations even when they were wrong, corresponding to subjective beliefs opposed to objective reality. Thus, view expectation is subjectively represented in human brain, and the fronto-parietal network is involved in integrating external cues and prior knowledge during spatial navigation. PMID:26631641

  11. Presence of lacunar infarctions is associated with the spatial navigation impairment in patients with mild cognitive impairment: a DTI study.

    PubMed

    Wu, Yan-Feng; Wu, Wen-Bo; Liu, Qing-Ping; He, Wen-Wen; Ding, Hong; Nedelska, Zuzana; Hort, Jakub; Zhang, Bing; Xu, Yun

    2016-11-29

    Lacunar cerebral infarction (LI) is one of risk factors of vascular dementia and correlates with progression of cognitive impairment including the executive functions. However, little is known on spatial navigation impairment and its underlying microstructural alteration of white matter in patients with LI and with or without mild cognitive impairment (MCI). Our aim was to investigate whether the spatial navigation impairment correlated with the white matter integrity in LI patients with MCI (LI-MCI). Thirty patients with LI were included in the study and were divided into LI-MCI (n=17) and non MCI (LI-Non MCI) groups (n=13) according neuropsychological tests.The microstructural integrity of white matter was assessed by calculating a fractional anisotropy (FA) and mean diffusivity (MD) from diffusion tensor imaging (DTI) scans. The spatial navigation accuracy, separately evaluated as egocentric and allocentric, was assessed by a computerized human analogue of the Morris Water Maze tests Amunet. LI-MCI performed worse than the CN and LI-NonMCI groups on egocentric and delayed spatial navigation subtests. LI-MCI patients have spatial navigation deficits. The microstructural abnormalities in diffuse brain regions, including hippocampus, uncinate fasciculus and other brain regions may contribute to the spatial navigation impairment in LI-MCI patients at follow-up.

  12. Presence of lacunar infarctions is associated with the spatial navigation impairment in patients with mild cognitive impairment: a DTI study

    PubMed Central

    Liu, Qing-Ping; He, Wen-Wen; Ding, Hong; Nedelska, Zuzana; Hort, Jakub; Zhang, Bing; Xu, Yun

    2016-01-01

    Lacunar cerebral infarction (LI) is one of risk factors of vascular dementia and correlates with progression of cognitive impairment including the executive functions. However, little is known on spatial navigation impairment and its underlying microstructural alteration of white matter in patients with LI and with or without mild cognitive impairment (MCI). Our aim was to investigate whether the spatial navigation impairment correlated with the white matter integrity in LI patients with MCI (LI-MCI). Thirty patients with LI were included in the study and were divided into LI-MCI (n=17) and non MCI (LI-Non MCI) groups (n=13) according neuropsychological tests.The microstructural integrity of white matter was assessed by calculating a fractional anisotropy (FA) and mean diffusivity (MD) from diffusion tensor imaging (DTI) scans. The spatial navigation accuracy, separately evaluated as egocentric and allocentric, was assessed by a computerized human analogue of the Morris Water Maze tests Amunet. LI-MCI performed worse than the CN and LI-NonMCI groups on egocentric and delayed spatial navigation subtests. LI-MCI patients have spatial navigation deficits. The microstructural abnormalities in diffuse brain regions, including hippocampus, uncinate fasciculus and other brain regions may contribute to the spatial navigation impairment in LI-MCI patients at follow-up. PMID:27861154

  13. Navigating through virtual environments: visual realism improves spatial cognition.

    PubMed

    Meijer, Frank; Geudeke, Branko L; van den Broek, Egon L

    2009-10-01

    Recent advances in computer technology have significantly facilitated the use of virtual environments (VE) for small and medium enterprises (SME). However, achieving visual realism in such VE requires high investments in terms of time and effort, while its usefulness has not yet become apparent from research. Other qualities of VE, such as the use of large displays, proved its effectiveness in enhancing the individual user's spatial cognition. The current study assessed whether the same benefits apply for visual realism in VE. Thirty-two participants were divided into two groups, who explored either a photorealistic or a nonrealistic supermarket presented on a large screen. The participants were asked to navigate through the supermarket on a predetermined route. Subsequently, spatial learning was tested in four pen-and-paper tests that assessed how accurately they had memorized the route and the environment's spatial layout. The study revealed increased spatial learning from the photorealistic compared to the nonrealistic supermarket. Specifically, participants performed better on tests that involved egocentric spatial knowledge. The results suggest visual realism is useful because it increases the user's spatial knowledge in the VE. Therefore, the current study provides clear evidence that it is worthwhile for SME to invest in achieving visual realism in VE.

  14. Interpreting collective neural activity underlying spatial navigation in virtual reality

    NASA Astrophysics Data System (ADS)

    Meshulam, Leenoy; Gauthier, Jeff; Tank, David; Bialek, William

    2015-03-01

    Traditionally, cognitive- demanding processes like spatial navigation were studied by recording the activity of single neurons. However, recent technological progress allows imaging the simultaneous activity of large neuronal populations in awake behaving animals. This progress in experimental work calls for a similar adjustments of the modeling frameworks. To achieve a description of the ``real thermodynamics'' of the neural system, we construct maximum entropy models for optical imaging data taken in vivo, from the hippocampus of mice navigating in a virtual reality environment. This provides a natural extension of statistical mechanics applicable to brain activity, by focusing on the interactions between cells rather than on single cell's activity. We aim to determine how the topology of the energy landscape predicted by the model corresponds to the location of the animal in the environment. Since large subpopulations of the neurons in this area are spatially modulated, we expect the landscape to exhibit a large ``valley'' structure of local minima, corresponding to the animal's position along the environment. Such a finding is especially of interest because the location information emerges solely from the activity patterns that are accessible to the brain.

  15. Maladaptive bias for extrahippocampal navigation strategies in aging humans.

    PubMed

    Wiener, Jan M; de Condappa, Olivier; Harris, Mathew A; Wolbers, Thomas

    2013-04-03

    Efficient spatial navigation requires not only accurate spatial knowledge but also the selection of appropriate strategies. Using a novel paradigm that allowed us to distinguish between beacon, associative cue, and place strategies, we investigated the effects of cognitive aging on the selection and adoption of navigation strategies in humans. Participants were required to rejoin a previously learned route encountered from an unfamiliar direction. Successful performance required the use of an allocentric place strategy, which was increasingly observed in young participants over six experimental sessions. In contrast, older participants, who were able to recall the route when approaching intersections from the same direction as during encoding, failed to use the correct place strategy when approaching intersections from novel directions. Instead, they continuously used a beacon strategy and showed no evidence of changing their behavior across the six sessions. Given that this bias was already apparent in the first experimental session, the inability to adopt the correct place strategy is not related to an inability to switch from a firmly established response strategy to an allocentric place strategy. Rather, and in line with previous research, age-related deficits in allocentric processing result in shifts in preferred navigation strategies and an overall bias for response strategies. The specific preference for a beacon strategy is discussed in the context of a possible dissociation between beacon-based and associative-cue-based response learning in the striatum, with the latter being more sensitive to age-related changes.

  16. [Change of white matter neuronal integrity associated with spatial navigation impairment in mild cognitive impairment].

    PubMed

    Li, W P; Wang, F F; Lu, J M; Wu, S C; Wu, W B; Liu, R Y; Zhang, X; Li, M; Zhao, H; Zhu, B; Xu, Y; Zhang, B

    2017-01-17

    mechanisms of human spatial navigation ability.

  17. A tesselated probabilistic representation for spatial robot perception and navigation

    NASA Technical Reports Server (NTRS)

    Elfes, Alberto

    1989-01-01

    The ability to recover robust spatial descriptions from sensory information and to efficiently utilize these descriptions in appropriate planning and problem-solving activities are crucial requirements for the development of more powerful robotic systems. Traditional approaches to sensor interpretation, with their emphasis on geometric models, are of limited use for autonomous mobile robots operating in and exploring unknown and unstructured environments. Here, researchers present a new approach to robot perception that addresses such scenarios using a probabilistic tesselated representation of spatial information called the Occupancy Grid. The Occupancy Grid is a multi-dimensional random field that maintains stochastic estimates of the occupancy state of each cell in the grid. The cell estimates are obtained by interpreting incoming range readings using probabilistic models that capture the uncertainty in the spatial information provided by the sensor. A Bayesian estimation procedure allows the incremental updating of the map using readings taken from several sensors over multiple points of view. An overview of the Occupancy Grid framework is given, and its application to a number of problems in mobile robot mapping and navigation are illustrated. It is argued that a number of robotic problem-solving activities can be performed directly on the Occupancy Grid representation. Some parallels are drawn between operations on Occupancy Grids and related image processing operations.

  18. Sexual Orientation-Related Differences in Virtual Spatial Navigation and Spatial Search Strategies.

    PubMed

    Rahman, Qazi; Sharp, Jonathan; McVeigh, Meadhbh; Ho, Man-Ling

    2017-04-11

    Spatial abilities are generally hypothesized to differ between men and women, and people with different sexual orientations. According to the cross-sex shift hypothesis, gay men are hypothesized to perform in the direction of heterosexual women and lesbian women in the direction of heterosexual men on cognitive tests. This study investigated sexual orientation differences in spatial navigation and strategy during a virtual Morris water maze task (VMWM). Forty-four heterosexual men, 43 heterosexual women, 39 gay men, and 34 lesbian/bisexual women (aged 18-54 years) navigated a desktop VMWM and completed measures of intelligence, handedness, and childhood gender nonconformity (CGN). We quantified spatial learning (hidden platform trials), probe trial performance, and cued navigation (visible platform trials). Spatial strategies during hidden and probe trials were classified into visual scanning, landmark use, thigmotaxis/circling, and enfilading. In general, heterosexual men scored better than women and gay men on some spatial learning and probe trial measures and used more visual scan strategies. However, some differences disappeared after controlling for age and estimated IQ (e.g., in visual scanning heterosexual men differed from women but not gay men). Heterosexual women did not differ from lesbian/bisexual women. For both sexes, visual scanning predicted probe trial performance. More feminine CGN scores were associated with lower performance among men and greater performance among women on specific spatial learning or probe trial measures. These results provide mixed evidence for the cross-sex shift hypothesis of sexual orientation-related differences in spatial cognition.

  19. Outside Looking In: Landmark Generalization in the Human Navigational System

    PubMed Central

    Vass, Lindsay K.; Ryan, Jack; Epstein, Russell A.

    2015-01-01

    The use of landmarks is central to many navigational strategies. Here we use multivoxel pattern analysis of fMRI data to understand how landmarks are coded in the human brain. Subjects were scanned while viewing the interiors and exteriors of campus buildings. Despite their visual dissimilarity, interiors and exteriors corresponding to the same building elicited similar activity patterns in the parahippocampal place area (PPA), retrosplenial complex (RSC), and occipital place area (OPA), three regions known to respond strongly to scenes and buildings. Generalization across stimuli depended on knowing the correspondences among them in the PPA but not in the other two regions, suggesting that the PPA is the key region involved in learning the different perceptual instantiations of a landmark. In contrast, generalization depended on the ability to freely retrieve information from memory in RSC, and it did not depend on familiarity or cognitive task in OPA. Together, these results suggest a tripartite division of labor, whereby PPA codes landmark identity, RSC retrieves spatial or conceptual information associated with landmarks, and OPA processes visual features that are important for landmark recognition. SIGNIFICANCE STATEMENT A central element of spatial navigation is the ability to recognize the landmarks that mark different places in the world. However, little is known about how the brain performs this function. Here we show that the parahippocampal place area (PPA), a region in human occipitotemporal cortex, exhibits key features of a landmark recognition mechanism. Specifically, the PPA treats different perceptual instantiations of the same landmark as representationally similar, but only when subjects have enough experience to know the correspondences among the stimuli. We also identify two other brain regions that exhibit landmark generalization, but with less sensitivity to familiarity. These results elucidate the brain networks involved in the learning and

  20. Cognitive Effects of Language on Human Navigation

    ERIC Educational Resources Information Center

    Shusterman, Anna; Ah Lee, Sang; Spelke, Elizabeth S.

    2011-01-01

    Language has been linked to spatial representation and behavior in humans, but the nature of this effect is debated. Here, we test whether simple verbal expressions improve 4-year-old children's performance in a disoriented search task in a small rectangular room with a single red landmark wall. Disoriented children's landmark-guided search for a…

  1. Cognitive mappers to creatures of habit: differential engagement of place and response learning mechanisms predicts human navigational behavior.

    PubMed

    Marchette, Steven A; Bakker, Arnold; Shelton, Amy L

    2011-10-26

    Learning to navigate plays an integral role in the survival of humans and other animals. Research on human navigation has largely focused on how we deliberately map out our world. However, many of us also have experiences of navigating on "autopilot" or out of habit. Animal models have identified this cognitive mapping versus habit learning as two dissociable systems for learning a space--a hippocampal place-learning system and a striatal response-learning system. Here, we use this dichotomy in humans to understand variability in navigational style by demonstrating that brain activation during spatial encoding can predict where a person's behavior falls on a continuum from a more flexible cognitive map-like strategy to a more rigid creature-of-habit approach. These findings bridge the wealth of knowledge gained from animal models and the study of human behavior, opening the door to a more comprehensive understanding of variability in human spatial learning and navigation.

  2. Pharmacological evidence is consistent with a prominent role of spatial memory in complex navigation

    PubMed Central

    2016-01-01

    The ability to learn about the spatial environment plays an important role in navigation, migration, dispersal, and foraging. However, our understanding of both the role of cognition in the development of navigation strategies and the mechanisms underlying these strategies is limited. We tested the hypothesis that complex navigation is facilitated by spatial memory in a population of Chrysemys picta that navigate with extreme precision (±3.5 m) using specific routes that must be learned prior to age three. We used scopolamine, a muscarinic acetylcholine receptor antagonist, to manipulate the cognitive spatial abilities of free-living turtles during naturally occurring overland movements. Experienced adults treated with scopolamine diverted markedly from their precise navigation routes. Naive juveniles lacking experience (and memory) were not affected by scopolamine, and thereby served as controls for perceptual or non-spatial cognitive processes associated with navigation. Further, neither adult nor juvenile movement was affected by methylscopolamine, a form of scopolamine that does not cross the blood–brain barrier, a control for the peripheral effects of scopolamine. Together, these results are consistent with a role of spatial cognition in complex navigation and highlight a cellular mechanism that might underlie spatial cognition. Overall, our findings expand our understanding of the development of complex cognitive abilities of vertebrates and the neurological mechanisms of navigation. PMID:26865305

  3. Pharmacological evidence is consistent with a prominent role of spatial memory in complex navigation.

    PubMed

    Roth, Timothy C; Krochmal, Aaron R

    2016-02-10

    The ability to learn about the spatial environment plays an important role in navigation, migration, dispersal, and foraging. However, our understanding of both the role of cognition in the development of navigation strategies and the mechanisms underlying these strategies is limited. We tested the hypothesis that complex navigation is facilitated by spatial memory in a population of Chrysemys picta that navigate with extreme precision (±3.5 m) using specific routes that must be learned prior to age three. We used scopolamine, a muscarinic acetylcholine receptor antagonist, to manipulate the cognitive spatial abilities of free-living turtles during naturally occurring overland movements. Experienced adults treated with scopolamine diverted markedly from their precise navigation routes. Naive juveniles lacking experience (and memory) were not affected by scopolamine, and thereby served as controls for perceptual or non-spatial cognitive processes associated with navigation. Further, neither adult nor juvenile movement was affected by methylscopolamine, a form of scopolamine that does not cross the blood-brain barrier, a control for the peripheral effects of scopolamine. Together, these results are consistent with a role of spatial cognition in complex navigation and highlight a cellular mechanism that might underlie spatial cognition. Overall, our findings expand our understanding of the development of complex cognitive abilities of vertebrates and the neurological mechanisms of navigation. © 2016 The Author(s).

  4. Dissociable cerebellar activity during spatial navigation and visual memory in bilateral vestibular failure.

    PubMed

    Jandl, N M; Sprenger, A; Wojak, J F; Göttlich, M; Münte, T F; Krämer, U M; Helmchen, C

    2015-10-01

    Spatial orientation and navigation depends on information from the vestibular system. Previous work suggested impaired spatial navigation in patients with bilateral vestibular failure (BVF). The aim of this study was to investigate event-related brain activity by functional magnetic resonance imaging (fMRI) during spatial navigation and visual memory tasks in BVF patients. Twenty-three BVF patients and healthy age- and gender matched control subjects performed learning sessions of spatial navigation by watching short films taking them through various streets from a driver's perspective along a route to the Cathedral of Cologne using virtual reality videos (adopted and modified from Google Earth). In the scanner, participants were asked to respond to questions testing for visual memory or spatial navigation while they viewed short video clips. From a similar but not identical perspective depicted video frames of routes were displayed which they had previously seen or which were completely novel to them. Compared with controls, posterior cerebellar activity in BVF patients was higher during spatial navigation than during visual memory tasks, in the absence of performance differences. This cerebellar activity correlated with disease duration. Cerebellar activity during spatial navigation in BVF patients may reflect increased non-vestibular efforts to counteract the development of spatial navigation deficits in BVF. Conceivably, cerebellar activity indicates a change in navigational strategy of BVF patients, i.e. from a more allocentric, landmark or place-based strategy (hippocampus) to a more sequence-based strategy. This interpretation would be in accord with recent evidence for a cerebellar role in sequence-based navigation. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  5. Gray and white matter correlates of navigational ability in humans.

    PubMed

    Wegman, Joost; Fonteijn, Hubert M; van Ekert, Janneke; Tyborowska, Anna; Jansen, Clemens; Janzen, Gabriele

    2014-06-01

    Humans differ widely in their navigational abilities. Studies have shown that self-reports on navigational abilities are good predictors of performance on navigation tasks in real and virtual environments. The caudate nucleus and medial temporal lobe regions have been suggested to subserve different navigational strategies. The ability to use different strategies might underlie navigational ability differences. This study examines the anatomical correlates of self-reported navigational ability in both gray and white matter. Local gray matter volume was compared between a group (N = 134) of good and bad navigators using voxel-based morphometry (VBM), as well as regional volumes. To compare between good and bad navigators, we also measured white matter anatomy using diffusion tensor imaging (DTI) and looked at fractional anisotropy (FA) values. We observed a trend toward higher local GM volume in right anterior parahippocampal/rhinal cortex for good versus bad navigators. Good male navigators showed significantly higher local GM volume in right hippocampus than bad male navigators. Conversely, bad navigators showed increased FA values in the internal capsule, the white matter bundle closest to the caudate nucleus and a trend toward higher local GM volume in the caudate nucleus. Furthermore, caudate nucleus regional volume correlated negatively with navigational ability. These convergent findings across imaging modalities are in line with findings showing that the caudate nucleus and the medial temporal lobes are involved in different wayfinding strategies. Our study is the first to show a link between self-reported large-scale navigational abilities and different measures of brain anatomy. Copyright © 2013 Wiley Periodicals, Inc.

  6. Design of a Virtual Reality Navigational (VRN) experiment for assessment of egocentric spatial cognition.

    PubMed

    Byagowi, Ahmad; Moussavi, Zahra

    2012-01-01

    Virtual reality (VR) experiments are commonly used to assess human brain functions. We orient ourselves in an environment by computing precise self-to-object spatial relations (egocentric orientation) as well as object-to-object spatial relations (allocentric orientation). Egocentric orientation involves cues that depend on the position of the observer (i.e. left-right, front-behind), whereas allocentric orientation is maintained through the use of environmental features such as landmarks. As such, allocentric orientation involves short-term memory, whereas egocentric orientation does not. This paper presents a Virtual Reality Navigational (VRN) experiment specifically designed to assess egocentric spatial cognition. The design aimed to minimize the effect of spatial cues or landmarks for human navigation in a naturalistic VR environment. The VRN experiment designed for this study, called the Virtual House, is a symmetric three story cubic building, with 3 windows on each side on every floor, and one entrance on each side of the building. In each trial, a window is marked by a pseudo-random sequence as the objective. The marked window is shown to the participant from an outdoor view. The task is to reach the objective window using the shortest path through the building. The experiment entails 2 sets of 8 trials to cover all possibilities. The participants' performance error is measured by the difference between their traversed distance trajectory and the shortest natural distance (calculated using the VR engine), normalized by the shortest distance, in each trial. Fifty-two cognitively healthy adults participated in the study. The results show no learning effect during the 16 trails, implying that the experiment does not rely on short-term memory. Furthermore, the subjects' normalized performance error showed an almost linear increase with age, implying that egocentric spatial cognition ability declines with age.

  7. How does horizontal and vertical navigation influence spatial memory of multifloored environments?

    PubMed

    Thibault, Guillaume; Pasqualotto, Achille; Vidal, Manuel; Droulez, Jacques; Berthoz, Alain

    2013-01-01

    Although a number of studies have been devoted to 2-D navigation, relatively little is known about how the brain encodes and recalls navigation in complex multifloored environments. Previous studies have proposed that humans preferentially memorize buildings by a set of horizontal 2-D representations. Yet this might stem from the fact that environments were also explored by floors. Here, we have investigated the effect of spatial learning on memory of a virtual multifloored building. Two groups of 28 participants watched a computer movie that showed either a route along floors one at a time or travel between floors by simulated lifts, consisting in both cases of a 2-D trajectory in the vertical plane. To test recognition, the participants viewed a camera movement that either replicated a segment of the learning route (familiar segment) or did not (novel segment-i.e., shortcuts). Overall, floor recognition was not reliably superior to column recognition, but learning along a floor route produced a better spatial memory performance than did learning along a column route. Moreover, the participants processed familiar segments more accurately than novel ones, not only after floor learning, but crucially, also after column learning, suggesting a key role of the observation mode on the exploitation of spatial memory.

  8. Differential effects of aging on spatial learning through exploratory navigation and map reading

    PubMed Central

    Yamamoto, Naohide; DeGirolamo, Gregory J.

    2012-01-01

    It has been shown that abilities in spatial learning and memory are adversely affected by aging. The present study was conducted to investigate whether increasing age has equal consequences for all types of spatial learning or impacts certain types of spatial learning selectively. Specifically, two major types of spatial learning, exploratory navigation and map reading, were contrasted. By combining a neuroimaging finding that the medial temporal lobe (MTL) is especially important for exploratory navigation and a neurological finding that the MTL is susceptible to age-related atrophy, it was hypothesized that spatial learning through exploratory navigation would exhibit a greater decline in later life than spatial learning through map reading. In an experiment, young and senior participants learned locations of landmarks in virtual environments either by navigating in them in the first-person perspective or by seeing aerial views of the environments. Results showed that senior participants acquired less accurate memories of the layouts of landmarks than young participants when they navigated in the environments, but the two groups did not differ in spatial learning performance when they viewed the environments from the aerial perspective. These results suggest that spatial learning through exploratory navigation is particularly vulnerable to adverse effects of aging, whereas elderly adults may be able to maintain their map reading skills relatively well. PMID:22701423

  9. Spatial and Temporal Abstractions in POMDPs Applied to Robot Navigation

    DTIC Science & Technology

    2005-09-27

    production states) approaches for robot navigation and mapping. We are beginning to explore methods that combine topological and metric SLAM ( Tomatis ...navigation. Ar- tificial Intelligence, pp. 21–71. Tomatis , N., Nourbakhsh, I., & Siegwart., R. (2003). Hybrid simultaneous map-building: A natural

  10. A Computational Model for Spatial Navigation Based on Reference Frames in the Hippocampus, Retrosplenial Cortex, and Posterior Parietal Cortex.

    PubMed

    Oess, Timo; Krichmar, Jeffrey L; Röhrbein, Florian

    2017-01-01

    Behavioral studies for humans, monkeys, and rats have shown that, while traversing an environment, these mammals tend to use different frames of reference and frequently switch between them. These frames represent allocentric, egocentric, or route-centric views of the environment. However, combinations of either of them are often deployed. Neurophysiological studies on rats have indicated that the hippocampus, the retrosplenial cortex, and the posterior parietal cortex contribute to the formation of these frames and mediate the transformation between those. In this paper, we construct a computational model of the posterior parietal cortex and the retrosplenial cortex for spatial navigation. We demonstrate how the transformation of reference frames could be realized in the brain and suggest how different brain areas might use these reference frames to form navigational strategies and predict under what conditions an animal might use a specific type of reference frame. Our simulated navigation experiments demonstrate that the model's results closely resemble behavioral findings in humans and rats. These results suggest that navigation strategies may depend on the animal's reliance in a particular reference frame and shows how low confidence in a reference frame can lead to fluid adaptation and deployment of alternative navigation strategies. Because of its flexibility, our biologically inspired navigation system may be applied to autonomous robots.

  11. A Computational Model for Spatial Navigation Based on Reference Frames in the Hippocampus, Retrosplenial Cortex, and Posterior Parietal Cortex

    PubMed Central

    Oess, Timo; Krichmar, Jeffrey L.; Röhrbein, Florian

    2017-01-01

    Behavioral studies for humans, monkeys, and rats have shown that, while traversing an environment, these mammals tend to use different frames of reference and frequently switch between them. These frames represent allocentric, egocentric, or route-centric views of the environment. However, combinations of either of them are often deployed. Neurophysiological studies on rats have indicated that the hippocampus, the retrosplenial cortex, and the posterior parietal cortex contribute to the formation of these frames and mediate the transformation between those. In this paper, we construct a computational model of the posterior parietal cortex and the retrosplenial cortex for spatial navigation. We demonstrate how the transformation of reference frames could be realized in the brain and suggest how different brain areas might use these reference frames to form navigational strategies and predict under what conditions an animal might use a specific type of reference frame. Our simulated navigation experiments demonstrate that the model’s results closely resemble behavioral findings in humans and rats. These results suggest that navigation strategies may depend on the animal’s reliance in a particular reference frame and shows how low confidence in a reference frame can lead to fluid adaptation and deployment of alternative navigation strategies. Because of its flexibility, our biologically inspired navigation system may be applied to autonomous robots. PMID:28223931

  12. Brain Oscillatory Activity during Spatial Navigation: Theta and Gamma Activity Link Medial Temporal and Parietal Regions

    ERIC Educational Resources Information Center

    White, David J.; Congedo, Marco; Ciorciari, Joseph; Silberstein, Richard B.

    2012-01-01

    Brain oscillatory correlates of spatial navigation were investigated using blind source separation (BSS) and standardized low resolution electromagnetic tomography (sLORETA) analyses of 62-channel EEG recordings. Twenty-five participants were instructed to navigate to distinct landmark buildings in a previously learned virtual reality town…

  13. Brain Oscillatory Activity during Spatial Navigation: Theta and Gamma Activity Link Medial Temporal and Parietal Regions

    ERIC Educational Resources Information Center

    White, David J.; Congedo, Marco; Ciorciari, Joseph; Silberstein, Richard B.

    2012-01-01

    Brain oscillatory correlates of spatial navigation were investigated using blind source separation (BSS) and standardized low resolution electromagnetic tomography (sLORETA) analyses of 62-channel EEG recordings. Twenty-five participants were instructed to navigate to distinct landmark buildings in a previously learned virtual reality town…

  14. Turning bias in virtual spatial navigation: age-related differences and neuroanatomical correlates.

    PubMed

    Yuan, Peng; Daugherty, Ana M; Raz, Naftali

    2014-02-01

    Rodents frequently exhibit rotational bias associated with asymmetry in lesions and neurotransmitters in the striatum. However, in humans, turning preference is inconsistent across studies, and its neural correlates are unclear. We examined turning bias in 140 right-handed healthy adults (18-77 years old), who navigated a virtual Morris Water Maze. On magnetic resonance images, we measured volumes of brain regions relevant to spatial navigation. We classified turns that occurred during virtual navigation as veering (less than 10°), true turns (between 10° and 90°) and course reversals (over 90°). The results showed that performance (time of platform search and distance traveled) was negatively related to age. The distance traveled was positively associated with volume of the orbito-frontal cortex but not with the volumes of the cerebellum, the hippocampus or the primary visual cortex. Examination of turning behavior showed that all participants veered to the right. In turns and reversals, although on average there was no consistent direction preference, we observed significant individual biases. Virtual turning preference correlated with volumetric asymmetry in the striatum, cerebellum, and hippocampus but not in the prefrontal cortex. Participants preferred to turn toward the hemisphere with larger putamen, cerebellum and (in younger adults only) hippocampus. Advanced age was associated with greater rightward turning preference. Men showed greater leftward preference whereas women exhibited stronger rightward bias. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Autonomous Navigation for Mobile Robots with Human-Robot Interaction

    NASA Astrophysics Data System (ADS)

    Ballantyne, James; Johns, Edward; Valibeik, Salman; Wong, Charence; Yang, Guang-Zhong

    Dynamic and complex indoor environments present a challenge for mobile robot navigation. The robot must be able to simultaneously map the environment, which often has repetitive features, whilst keep track of its pose and location. This chapter introduces some of the key considerations for human guided navigation. Rather than letting the robot explore the environment fully autonomously, we consider the use of human guidance for progressively building up the environment map and establishing scene association, learning, as well as navigation and planning. After the guide has taken the robot through the environment and indicated the points of interest via hand gestures, the robot is then able to use the geometric map and scene descriptors captured during the tour to create a high-level plan for subsequent autonomous navigation within the environment. Issues related to gesture recognition, multi-cue integration, tracking, target pursuing, scene association and navigation planning are discussed.

  16. Human Factors Considerations for Performance-Based Navigation

    NASA Technical Reports Server (NTRS)

    Barhydt, Richard; Adams, Catherine A.

    2006-01-01

    A transition toward a performance-based navigation system is currently underway in both the United States and around the world. Performance-based navigation incorporates Area Navigation (RNAV) and Required Navigation Performance (RNP) procedures that do not rely on the location of ground-based navigation aids. These procedures offer significant benefits to both operators and air traffic managers. Under sponsorship from the Federal Aviation Administration (FAA), the National Aeronautics and Space Administration (NASA) has undertaken a project to document human factors issues that have emerged during RNAV and RNP operations and propose areas for further consideration. Issues were found to include aspects of air traffic control and airline procedures, aircraft systems, and procedure design. Major findings suggest the need for human factors-specific instrument procedure design guidelines. Ongoing industry and government activities to address air-ground communication terminology, procedure design improvements, and chart-database commonality are strongly encouraged.

  17. Navigating the human hippocampus without a GPS.

    PubMed

    Zucker, Halle R; Ranganath, Charan

    2015-06-01

    The award of the Nobel Prize to Professors John O'Keefe, May-Britt Moser, and Edvard Moser brings global recognition to one of the most significant success stories in modern neuroscience. Here, we consider how their findings, along with related studies of spatial cognition in rodents, have informed our understanding of the human hippocampus. Rather than identifying a "GPS" in the brain, we emphasize that these researchers helped to establish a fundamental role for cortico-hippocampal networks in the guidance of behavior based on a representation of the current place, time, and situation. We conclude by highlighting the major questions that remain to be addressed in future research.

  18. Reduced Parahippocampal Theta Activity During Spatial Navigation in Low, but Not in High Elderly Performers.

    PubMed

    Lithfous, Ségolène; Dufour, André; Bouix, Cloé; Pebayle, Thierry; Després, Olivier

    2017-06-29

    Cognitive aging varies widely among individuals. Whereas optimal cognitive agers show highly preserved cognitive functions throughout life, other subjects experience cognitive deficits in various cognitive domains. Among them, elderly individuals frequently report difficulties in spatial navigation. In this study, we aimed to determine whether elderly participants with different cognitive profiles would perform differently at a navigation task, and explore underlying medial hippocampal activity. Two groups of elderly subjects were selected, high- and low-performing (HP and LP, respectively), based on their performance on a detailed neuropsychological examination. A group of young adults was recruited as controls. Cerebral activity was recorded by electroencephalography (EEG) during a virtual navigation task in which participants had 3 trials to find their way in mazes. We analyzed theta activity during navigation in the mazes and performed source reconstruction analyses. The LP group was less accurate than the HP group during the navigation task. Theta activity during navigation was greater in HP subjects compared with controls, whereas that theta activity was reduced in LP subjects. Moreover, theta activity in the left parahippocampal gyrus increased across trials in HP, but not in LP, subjects. Elderly participants performed differently at a navigation task according to their cognitive profile: elderly with cognitive deficits seem to have greater difficulties in spatial navigation than HP elderly. Navigational difficulties in elderly with cognitive deficits might be related to functional alteration of the parahippocampal gyrus. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  19. The effects of spatial representation on memory for verbal navigation instructions.

    PubMed

    Barshi, Immanuel; Healy, Alice F

    2011-01-01

    Three experiments investigated effects of mental spatial representation on memory for verbal navigation instructions. The navigation instructions referred to a grid of stacked matrices displayed on a computer screen or on paper, with or without depth cues, and presented as two-dimensional diagrams or a three-dimensional physical model. Experimental instructions either did or did not promote a three-dimensional mental representation of the space. Subjects heard navigation instructions, immediately repeated them, and then followed them manually on the grid. In all display and experimental instruction conditions, memory for the navigation instructions was reduced when the task required mentally representing a three-dimensional space, with movements across multiple matrices, as compared with a two-dimensional space, with movements within a single matrix, even though the words in the navigation instructions were identical in all cases. The findings demonstrate that the mental representation of the space influences immediate verbatim memory for navigation instructions.

  20. Modeling the Contributions of Basal Ganglia and Hippocampus to Spatial Navigation Using Reinforcement Learning

    PubMed Central

    Sukumar, Deepika; Rengaswamy, Maithreye; Chakravarthy, V. Srinivasa

    2012-01-01

    A computational neural model that describes the competing roles of Basal Ganglia and Hippocampus in spatial navigation is presented. Model performance is evaluated on a simulated Morris water maze explored by a model rat. Cue-based and place-based navigational strategies, thought to be subserved by the Basal ganglia and Hippocampus respectively, are described. In cue-based navigation, the model rat learns to directly head towards a visible target, while in place-based navigation the target position is represented in terms of spatial context provided by an array of poles placed around the pool. Learning is formulated within the framework of Reinforcement Learning, with the nigrostriatal dopamine signal playing the role of Temporal Difference Error. Navigation inherently involves two apparently contradictory movements: goal oriented movements vs. random, wandering movements. The model hypothesizes that while the goal-directedness is determined by the gradient in Value function, randomness is driven by the complex activity of the SubThalamic Nucleus (STN)-Globus Pallidus externa (GPe) system. Each navigational system is associated with a Critic, prescribing actions that maximize value gradients for the corresponding system. In the integrated system, that incorporates both cue-based and place-based forms of navigation, navigation at a given position is determined by the system whose value function is greater at that position. The proposed model describes the experimental results of [1], a lesion-study that investigates the competition between cue-based and place-based navigational systems. The present study also examines impaired navigational performance under Parkinsonian-like conditions. The integrated navigational system, operated under dopamine-deficient conditions, exhibits increased escape latency as was observed in experimental literature describing MPTP model rats navigating a water maze. PMID:23110073

  1. Kinesthetic and vestibular information modulate alpha activity during spatial navigation: a mobile EEG study

    PubMed Central

    Ehinger, Benedikt V.; Fischer, Petra; Gert, Anna L.; Kaufhold, Lilli; Weber, Felix; Pipa, Gordon; König, Peter

    2014-01-01

    In everyday life, spatial navigation involving locomotion provides congruent visual, vestibular, and kinesthetic information that need to be integrated. Yet, previous studies on human brain activity during navigation focus on stationary setups, neglecting vestibular and kinesthetic feedback. The aim of our work is to uncover the influence of those sensory modalities on cortical processing. We developed a fully immersive virtual reality setup combined with high-density mobile electroencephalography (EEG). Participants traversed one leg of a triangle, turned on the spot, continued along the second leg, and finally indicated the location of their starting position. Vestibular and kinesthetic information was provided either in combination, as isolated sources of information, or not at all within a 2 × 2 full factorial intra-subjects design. EEG data were processed by clustering independent components, and time-frequency spectrograms were calculated. In parietal, occipital, and temporal clusters, we detected alpha suppression during the turning movement, which is associated with a heightened demand of visuo-attentional processing and closely resembles results reported in previous stationary studies. This decrease is present in all conditions and therefore seems to generalize to more natural settings. Yet, in incongruent conditions, when different sensory modalities did not match, the decrease is significantly stronger. Additionally, in more anterior areas we found that providing only vestibular but no kinesthetic information results in alpha increase. These observations demonstrate that stationary experiments omit important aspects of sensory feedback. Therefore, it is important to develop more natural experimental settings in order to capture a more complete picture of neural correlates of spatial navigation. PMID:24616681

  2. Slime mold uses an externalized spatial “memory” to navigate in complex environments

    PubMed Central

    Reid, Chris R.; Latty, Tanya; Dussutour, Audrey; Beekman, Madeleine

    2012-01-01

    Spatial memory enhances an organism’s navigational ability. Memory typically resides within the brain, but what if an organism has no brain? We show that the brainless slime mold Physarum polycephalum constructs a form of spatial memory by avoiding areas it has previously explored. This mechanism allows the slime mold to solve the U-shaped trap problem—a classic test of autonomous navigational ability commonly used in robotics—requiring the slime mold to reach a chemoattractive goal behind a U-shaped barrier. Drawn into the trap, the organism must rely on other methods than gradient-following to escape and reach the goal. Our data show that spatial memory enhances the organism’s ability to navigate in complex environments. We provide a unique demonstration of a spatial memory system in a nonneuronal organism, supporting the theory that an externalized spatial memory may be the functional precursor to the internal memory of higher organisms. PMID:23045640

  3. Slime mold uses an externalized spatial "memory" to navigate in complex environments.

    PubMed

    Reid, Chris R; Latty, Tanya; Dussutour, Audrey; Beekman, Madeleine

    2012-10-23

    Spatial memory enhances an organism's navigational ability. Memory typically resides within the brain, but what if an organism has no brain? We show that the brainless slime mold Physarum polycephalum constructs a form of spatial memory by avoiding areas it has previously explored. This mechanism allows the slime mold to solve the U-shaped trap problem--a classic test of autonomous navigational ability commonly used in robotics--requiring the slime mold to reach a chemoattractive goal behind a U-shaped barrier. Drawn into the trap, the organism must rely on other methods than gradient-following to escape and reach the goal. Our data show that spatial memory enhances the organism's ability to navigate in complex environments. We provide a unique demonstration of a spatial memory system in a nonneuronal organism, supporting the theory that an externalized spatial memory may be the functional precursor to the internal memory of higher organisms.

  4. a Framework of Cognitive Indoor Navigation Based on Characteristics of Indoor Spatial Environment

    NASA Astrophysics Data System (ADS)

    Si, R.; Arikawa, M.

    2015-05-01

    People are easy to get confused in indoor spatial environment. Thus, indoor navigation systems on mobile devices are expected in a wide variety of application domains. Limited by the accuracy of indoor positioning, indoor navigating systems are not common in our society. However, automatic positioning is not all about location-based services (LBS), other factors, such as good map design and user interfaces, are also important to satisfy users of LBS. Indoor spatial environment and people's indoor spatial cognition are different than those in outdoor environment, which asks for different design of LBS. This paper introduces our design methods of indoor navigation system based on the characteristics of indoor spatial environment and indoor spatial cognition.

  5. Viewpoint tethering for remotely operated vehicles: effects on complex terrain navigation and spatial awareness.

    PubMed

    Hollands, Justin G; Lamb, Matthew

    2011-04-01

    The effect of viewpoint on the navigation of complex terrain and on spatial awareness was examined with the use of a simulated remotely operated vehicle. The ability to build terrain models in real time may soon allow remote vehicular control from any viewpoint. A virtual tether couples the viewpoint to the vehicle's position and orientation, but shows more of the terrain than a fully immersive egocentric display. In this sense, it provides visual momentum by providing a view that incorporates egocentric and exocentric qualities. For this study, 12 participants navigated a simulated vehicle across complex virtual terrain using five different display viewpoints: egocentric, dynamic tether, rigid tether, 3-D exocentric, and 2-D exocentric. While navigating, participants had to avoid being seen by simulated enemy units. After the navigation task, participants' spatial awareness was assessed using a recognition task. The tethered displays minimized the time during which the participant's vehicle was visible to enemy positions. The egocentric display was more effective than exocentric displays (2-D or 3-D) for navigation, and the exocentric displays were more effective than egocentric for time seen during navigation and the recognition task. The tethered displays produced intermediate results for navigation and recognition. Viewpoint tethering produced the most effective displays for minimizing time seen, but tethered displays were less effective than egocentric and exocentric displays for navigation and recognition, respectively. A tethered display is recommended for applications in which it is necessary to understand the relation of nearby locations to one's own location.

  6. Mechanisms for Human Spatial Competence

    NASA Astrophysics Data System (ADS)

    Gunzelmann, Glenn; Lyon, Don R.

    Research spanning decades has generated a long list of phenomena associated with human spatial information processing. Additionally, a number of theories have been proposed about the representation, organization and processing of spatial information by humans. This paper presents a broad account of human spatial competence, integrated with the ACT-R cognitive architecture. Using a cognitive architecture grounds the research in a validated theory of human cognition, enhancing the plausibility of the overall account. This work posits a close link of aspects of spatial information processing to vision and motor planning, and integrates theoretical perspectives that have been proposed over the history of research in this area. In addition, the account is supported by evidence from neuropsychological investigations of human spatial ability. The mechanisms provide a means of accounting for a broad range of phenomena described in the experimental literature.

  7. Wayfinding in the Blind: Larger Hippocampal Volume and Supranormal Spatial Navigation

    ERIC Educational Resources Information Center

    Fortin, Madeleine; Voss, Patrice; Lord, Catherine; Lassonde, Maryse; Pruessner, Jens; Saint-Amour, Dave; Rainville, Constant; Lepore, Franco

    2008-01-01

    In the absence of visual input, the question arises as to how complex spatial abilities develop and how the brain adapts to the absence of this modality. We explored navigational skills in both early and late blind individuals and structural differences in the hippocampus, a brain region well known to be involved in spatial processing.…

  8. Wayfinding in the Blind: Larger Hippocampal Volume and Supranormal Spatial Navigation

    ERIC Educational Resources Information Center

    Fortin, Madeleine; Voss, Patrice; Lord, Catherine; Lassonde, Maryse; Pruessner, Jens; Saint-Amour, Dave; Rainville, Constant; Lepore, Franco

    2008-01-01

    In the absence of visual input, the question arises as to how complex spatial abilities develop and how the brain adapts to the absence of this modality. We explored navigational skills in both early and late blind individuals and structural differences in the hippocampus, a brain region well known to be involved in spatial processing.…

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

    PubMed Central

    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. PMID

  10. Acute loss of spatial navigational skills in a case of a right posterior hippocampus stroke.

    PubMed

    Aradillas, Enrique; Libon, David J; Schwartzman, Robert J

    2011-09-15

    The ability to accurately navigate within an environment (known or new) is not fully understood but involves a number of highly complicated cognitive process related to both central and peripheral nervous system structures and neuronal networks. We describe a patient who developed loss of his spatial navigational skills associated with an acute ischemic right posterior hippocampal lesion. Neuropsychological assessment displayed clear evidence of impaired visuospatial/visuoconstructional abilities with relative preservation of many other cognitive functions involving orientation, language, and verbal memory. The underlying anatomy responsible for the navigational impairment seen in our patient could be due to impairment in the function of the right hippocampus to form, store, and retrieve new 'cognitive/spatial maps'. To our knowledge this is one of the few documented cases demonstrating impaired navigational abilities with a relatively discrete right-sided, posterior hippocampal lesion. Copyright © 2011. Published by Elsevier B.V.

  11. Spatial Navigation and the Central Complex: Sensory Acquisition, Orientation, and Motor Control

    PubMed Central

    Varga, Adrienn G.; Kathman, Nicholas D.; Martin, Joshua P.; Guo, Peiyuan; Ritzmann, Roy E.

    2017-01-01

    Cockroaches are scavengers that forage through dark, maze-like environments. Like other foraging animals, for instance rats, they must continually asses their situation to keep track of targets and negotiate barriers. While navigating a complex environment, all animals need to integrate sensory information in order to produce appropriate motor commands. The integrated sensory cues can be used to provide the animal with an environmental and contextual reference frame for the behavior. To successfully reach a goal location, navigational cues continuously derived from sensory inputs have to be utilized in the spatial guidance of motor commands. The sensory processes, contextual and spatial mechanisms, and motor outputs contributing to navigation have been heavily studied in rats. In contrast, many insect studies focused on the sensory and/or motor components of navigation, and our knowledge of the abstract representation of environmental context and spatial information in the insect brain is relatively limited. Recent reports from several laboratories have explored the role of the central complex (CX), a sensorimotor region of the insect brain, in navigational processes by recording the activity of CX neurons in freely-moving insects and in more constrained, experimenter-controlled situations. The results of these studies indicate that the CX participates in processing the temporal and spatial components of sensory cues, and utilizes these cues in creating an internal representation of orientation and context, while also directing motor control. Although these studies led to a better understanding of the CX's role in insect navigation, there are still major voids in the literature regarding the underlying mechanisms and brain regions involved in spatial navigation. The main goal of this review is to place the above listed findings in the wider context of animal navigation by providing an overview of the neural mechanisms of navigation in rats and summarizing and

  12. Spatial Navigation and the Central Complex: Sensory Acquisition, Orientation, and Motor Control.

    PubMed

    Varga, Adrienn G; Kathman, Nicholas D; Martin, Joshua P; Guo, Peiyuan; Ritzmann, Roy E

    2017-01-01

    Cockroaches are scavengers that forage through dark, maze-like environments. Like other foraging animals, for instance rats, they must continually asses their situation to keep track of targets and negotiate barriers. While navigating a complex environment, all animals need to integrate sensory information in order to produce appropriate motor commands. The integrated sensory cues can be used to provide the animal with an environmental and contextual reference frame for the behavior. To successfully reach a goal location, navigational cues continuously derived from sensory inputs have to be utilized in the spatial guidance of motor commands. The sensory processes, contextual and spatial mechanisms, and motor outputs contributing to navigation have been heavily studied in rats. In contrast, many insect studies focused on the sensory and/or motor components of navigation, and our knowledge of the abstract representation of environmental context and spatial information in the insect brain is relatively limited. Recent reports from several laboratories have explored the role of the central complex (CX), a sensorimotor region of the insect brain, in navigational processes by recording the activity of CX neurons in freely-moving insects and in more constrained, experimenter-controlled situations. The results of these studies indicate that the CX participates in processing the temporal and spatial components of sensory cues, and utilizes these cues in creating an internal representation of orientation and context, while also directing motor control. Although these studies led to a better understanding of the CX's role in insect navigation, there are still major voids in the literature regarding the underlying mechanisms and brain regions involved in spatial navigation. The main goal of this review is to place the above listed findings in the wider context of animal navigation by providing an overview of the neural mechanisms of navigation in rats and summarizing and

  13. Sex Differences and Menstrual Cycle Dependent Changes in Cognitive Strategies during Spatial Navigation and Verbal Fluency

    PubMed Central

    Scheuringer, Andrea; Pletzer, Belinda

    2017-01-01

    Men typically outperform women in spatial navigation tasks, while the advantage of women in verbal fluency is more controversial. Sex differences in cognitive abilities have been related to sex-specific cognitive strategies on the one hand and sex hormone influences on the other hand. However, sex hormone and menstrual cycle influences on cognitive strategies have not been previously investigated. In the present study we assessed cognitive strategy use during spatial navigation and verbal fluency in 51 men and 49 women. In order to evaluate sex hormone influences, all participants completed two test sessions, which were time-locked to the early follicular (low estradiol and progesterone) and mid-luteal cycle phase (high estradiol and progesterone) in women. As hypothesized, men outperformed women in navigation, whereas women outperformed men in phonemic verbal fluency. Furthermore, women switched more often between categories in the phonemic fluency condition, compared to men, indicating sex-specific strategy use. Sex differences in strategy use during navigation did, however, not follow the expected pattern. Menstrual cycle phase, however, did modulate strategy use during navigation as expected, with improved performance with the landmark strategy in the luteal, compared to the follicular phase. No menstrual cycle effects were observed on clustering or switching during verbal fluency. This suggests a modulation of cognitive strategy use during spatial navigation, but not during verbal fluency, by relative hormone increases during the luteal phase of the menstrual cycle. PMID:28367133

  14. Sex Differences and Menstrual Cycle Dependent Changes in Cognitive Strategies during Spatial Navigation and Verbal Fluency.

    PubMed

    Scheuringer, Andrea; Pletzer, Belinda

    2017-01-01

    Men typically outperform women in spatial navigation tasks, while the advantage of women in verbal fluency is more controversial. Sex differences in cognitive abilities have been related to sex-specific cognitive strategies on the one hand and sex hormone influences on the other hand. However, sex hormone and menstrual cycle influences on cognitive strategies have not been previously investigated. In the present study we assessed cognitive strategy use during spatial navigation and verbal fluency in 51 men and 49 women. In order to evaluate sex hormone influences, all participants completed two test sessions, which were time-locked to the early follicular (low estradiol and progesterone) and mid-luteal cycle phase (high estradiol and progesterone) in women. As hypothesized, men outperformed women in navigation, whereas women outperformed men in phonemic verbal fluency. Furthermore, women switched more often between categories in the phonemic fluency condition, compared to men, indicating sex-specific strategy use. Sex differences in strategy use during navigation did, however, not follow the expected pattern. Menstrual cycle phase, however, did modulate strategy use during navigation as expected, with improved performance with the landmark strategy in the luteal, compared to the follicular phase. No menstrual cycle effects were observed on clustering or switching during verbal fluency. This suggests a modulation of cognitive strategy use during spatial navigation, but not during verbal fluency, by relative hormone increases during the luteal phase of the menstrual cycle.

  15. Exploring the contribution of spatial navigation to cognitive functioning in older adults.

    PubMed

    Laczó, Jan; Andel, Ross; Nedelska, Zuzana; Vyhnalek, Martin; Vlcek, Kamil; Crutch, Sebastian; Harrison, John; Hort, Jakub

    2017-03-01

    Spatial navigation (SN) impairment is present early in Alzheimer's disease (AD). We tested whether SN performance, self-centered (egocentric) and world-centered (allocentric), was distinguishable from performance on established cognitive functions-verbal and nonverbal memory, executive and visuospatial function, attention/working memory, and language function. 108 older adults (53 cognitively normal [CN] and 55 with amnestic mild cognitive impairment [aMCI]) underwent neuropsychological examination and real-space navigation testing. Subset (n = 63) had automated hippocampal volumetry. In a factor analysis, allocentric and egocentric navigation tasks loaded highly onto the same factor with low loadings on other factors comprising other cognitive functions. In linear regression, performance on other cognitive functions was not, or was only marginally, associated with spatial navigation performance in CN or aMCI groups. After adjustment for age, gender, and education, right hippocampal volume explained 26% of the variance in allocentric navigation in aMCI group. In conclusion, spatial navigation, a known cognitive marker of early AD, may be distinguished from other cognitive functions. Therefore, its assessment along with other major cognitive functions may be highly beneficial in terms of obtaining a comprehensive neuropsychological profile. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Proximal versus distal cue utilization in spatial navigation: the role of visual acuity?

    PubMed

    Carman, Heidi M; Mactutus, Charles F

    2002-09-01

    Proximal versus distal cue use in the Morris water maze is a widely accepted strategy for the dissociation of various problems affecting spatial navigation in rats such as aging, head trauma, lesions, and pharmacological or hormonal agents. Of the limited number of ontogenetic rat studies conducted, the majority have approached the problem of preweanling spatial navigation through a similar proximal-distal dissociation. An implicit assumption among all of these studies has been that the animal's visual system is sufficient to permit robust spatial navigation. We challenged this assumption and have addressed the role of visual acuity in spatial navigation in the preweanling Fischer 344-N rat by training animals to locate a visible (proximal) or hidden (distal) platform using double or null extramaze cues within the testing environment. All pups demonstrated improved performance across training, but animals presented with a visible platform, regardless of extramaze cues, simultaneously reached asymptotic performance levels; animals presented with a hidden platform, dependent upon location of extramaze cues, differentially reached asymptotic performance levels. Probe trial performance, defined by quadrant time and platform crossings, revealed that distal-double-cue pups demonstrated spatial navigational ability superior to that of the remaining groups. These results suggest that a pup's ability to spatially navigate a hidden platform is dependent on not only its response repertoire and task parameters, but also its visual acuity, as determined by the extramaze cue location within the testing environment. The standard hidden versus visible platform dissociation may not be a satisfactory strategy for the control of potential sensory deficits.

  17. Can Active Navigation Be as Good as Driving? A Comparison of Spatial Memory in Drivers and Backseat Drivers

    ERIC Educational Resources Information Center

    von Stulpnagel, Rul; Steffens, Melanie C.

    2012-01-01

    When driving a vehicle, either the driver or a passenger (henceforth: backseat driver) may be responsible for navigation. Research on active navigation, primarily addressed in virtual environments, suggests that controlling navigation is more central for spatial learning than controlling movement. To test this assumption in a real-world scenario,…

  18. Can Active Navigation Be as Good as Driving? A Comparison of Spatial Memory in Drivers and Backseat Drivers

    ERIC Educational Resources Information Center

    von Stulpnagel, Rul; Steffens, Melanie C.

    2012-01-01

    When driving a vehicle, either the driver or a passenger (henceforth: backseat driver) may be responsible for navigation. Research on active navigation, primarily addressed in virtual environments, suggests that controlling navigation is more central for spatial learning than controlling movement. To test this assumption in a real-world scenario,…

  19. Multimodal sensory integration and concurrent navigation strategies for spatial cognition in real and artificial organisms.

    PubMed

    Arleo, Angelo; Rondi-Reig, Laure

    2007-09-01

    Flexible spatial behavior requires the ability to orchestrate the interaction of multiple parallel processes. At the sensory level, multimodal inputs must be combined to produce a robust description of the spatiotemporal properties of the environment. At the action-selection level, multiple concurrent navigation policies must be dynamically weighted in order to adopt the strategy that is the most adapted to the complexity of the task. Different neural substrates mediate the processing of spatial information. Elucidating their anatomo-functional interrelations is fundamental to unravel the overall spatial memory function. Here we first address the multisensory integration issue and we review a series of experimental findings (both behavioral and electrophysiological) concerning the neural bases of spatial learning and the way the brain builds unambiguous spatial representations from incoming multisensory streams. Second, we move at the navigation strategy level and present an overview of experimental data that begin to explain the cooperation-competition between the brain areas involved in spatial navigation. Third, we introduce the spatial cognition function from a computational neuroscience and neuro-robotics viewpoint. We provide an example of neuro-computational model that focuses on the importance of combining multisensory percepts to enable a robot to acquire coherent (spatial) memories of its interaction with the environment.

  20. Electrophysiological correlates of high-level perception during spatial navigation

    PubMed Central

    Weidemann, Christoph T.; Mollison, Matthew V.; Kahana, Michael J.

    2009-01-01

    We studied the electrophysiological basis o object recognition by recording scalp EEG while participants played a virtual reality taxi driver game. Participants searched for passengers and stores during virtual navigation in simulated towns. We compared oscillatory brain activity for store views that were targets or non-targets (during store search) or neutral (during passenger search). Even though store category was solely defined by task context (rather than sensory cues), frontal electrophysiological activity in low frequency bands (primarily in the theta [4–8 Hz] band) reliably distinguished between target, non-target, and neutral store views. These results implicate low frequency oscillatory brain activity in frontal regions as an important variable in the study of cognitive processes involved in object recognition, categorization, and other forms of high-level perception. PMID:19293100

  1. Navigating Web-Based Environments: Differentiating Internal Spatial Representations from External Spatial Displays

    ERIC Educational Resources Information Center

    Schwartz, Neil H.; Verdi, Michael P.; Morris, Terra D.; Lee, Tiffany R.; Larson, Nikki K.

    2007-01-01

    Fifty-five undergraduate students read pages on a website presenting text about familiar and unfamiliar geographic locations in the United States. Learners navigated the site by having available or unavailable navigational buttons showing the cardinal compass directions between the map locations in the presence or absence of a cartographic map…

  2. Effectiveness of maritime safety control in different navigation zones using a spatial sequential DEA model: Yangtze River case.

    PubMed

    Wu, Bing; Wang, Yang; Zhang, Jinfen; Savan, Emanuel Emil; Yan, Xinping

    2015-08-01

    This paper aims to analyze the effectiveness of maritime safety control from the perspective of safety level along the Yangtze River with special considerations for navigational environments. The influencing variables of maritime safety are reviewed, including ship condition, maritime regulatory system, human reliability and navigational environment. Because the former three variables are generally assumed to be of the same level of safety, this paper focuses on studying the impact of navigational environments on the level of safety in different waterways. An improved data envelopment analysis (DEA) model is proposed by treating the navigational environment factors as inputs and ship accident data as outputs. Moreover, because the traditional DEA model cannot provide an overall ranking of different decision making units (DMUs), the spatial sequential frontiers and grey relational analysis are incorporated into the DEA model to facilitate a refined assessment. Based on the empirical study results, the proposed model is able to solve the problem of information missing in the prior models and evaluate the level of safety with a better accuracy. The results of the proposed DEA model are further compared with an evidential reasoning (ER) method, which has been widely used for level of safety evaluations. A sensitivity analysis is also conducted to better understand the relationship between the variation of navigational environments and level of safety. The sensitivity analysis shows that the level of safety varies in terms of traffic flow. It indicates that appropriate traffic control measures should be adopted for different waterways to improve their safety. This paper presents a practical method of conducting maritime level of safety assessments under dynamic navigational environment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. 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.

  4. Differences in Spatial Knowledge Acquired from Maps and Navigation.

    DTIC Science & Technology

    1980-12-01

    1980 N-1595-ONR Prepared For The Office of Naval Research S ELECTE FEB 1 0 1981 " \\ E Rnd ISdiA AOMCA~ CA. 40 Ao 2A ,, , DUMO ,,LI,,,tO 006 This...76311 53 Majr JacK A. Thorpe, USAF NavjL Wir Coileqe Provilence. al 02846 DIPARrMENT OF rilz MARINES 54 H. dilli~a Greenup Educition Advisor CE031...Lduration Cetner, 1CDEC OUantic , VA 22134 N-1595-ONB DIFFERENCES IN SPATIAL KNOWLEDGE... 12/19/90 PAGE 7 55 Major Howard Lanqdon tiq.. Marine Corps OTTI

  5. Cognitive Mappers to Creatures of Habit: Differential Engagement of Place and Response Learning Mechanisms Predicts Human Navigational Behavior

    PubMed Central

    Marchette, Steven A.; Bakker, Arnold; Shelton, Amy L.

    2016-01-01

    Learning to navigate plays an integral role in the survival of humans and other animals. Research on human navigation has largely focused on how we deliberately map out our world. However, many of us also have experiences of navigating on “autopilot” or out of habit. Animal models have identified this cognitive mapping versus habit learning as two dissociable systems for learning a space—a hippocampal place-learning system and a striatal response-learning system. Here, we use this dichotomy in humans to understand variability in navigational style by demonstrating that brain activation during spatial encoding can predict where a person’s behavior falls on a continuum from a more flexible cognitive map-like strategy to a more rigid creature-of-habit approach. These findings bridge the wealth of knowledge gained from animal models and the study of human behavior, opening the door to a more comprehensive understanding of variability in human spatial learning and navigation. PMID:22031872

  6. An investigation of the validity of the virtual spatial navigation assessment

    PubMed Central

    Ventura, Matthew; Shute, Valerie; Wright, Tim; Zhao, Weinan

    2013-01-01

    This correlational study investigated a new measure of environmental spatial ability (i.e., large scale spatial ability) called the virtual spatial navigation assessment (VSNA). In the VSNA, participants must find a set of gems in a virtual 3D environment using a first person avatar on a computer. The VSNA runs in a web browser and automatically collects the time taken to find each gem. The time taken to collect gems in the VSNA was significantly correlated to three other spatial ability measures, math standardized test scores, and choice to be in a STEM (science, technology, engineering, or math) career. These findings support the validity of the VSNA as a measure of environmental spatial ability. Finally, self-report video game experience was also significantly correlated to the VSNA suggesting that video game may improve environmental spatial ability. Recommendations are made for how the VSNA can be used to help guide individuals toward STEM career paths and identify weaknesses that might be addressed with large scale spatial navigation training. PMID:24379790

  7. Optic flow helps humans learn to navigate through synthetic environments.

    PubMed

    Kirschen, M P; Kahana, M J; Sekuler, R; Burack, B

    2000-01-01

    Self-movement through an environment generates optic flow, a potential source of heading information. But it is not certain that optic flow is sufficient to support navigation, particularly navigation along complex, multi-legged paths. To address this question, we studied human participants who navigated synthetic environments with and without salient optic flow. Participants used a keyboard to control realistic simulation of self-movement through computer-rendered, synthetic environments. Because these environments comprised series of identically textured virtual corridors and intersections, participants had to build up some mental representation of the environment in order to perform. The impact of optic flow on learning was examined in two experiments. In experiment 1, participants learned to navigate multiple T-junction mazes with and without accompanying optic flow. Optic flow promoted faster learning, mainly by preventing disorientation and backtracking in the maze. In experiment 2, participants found their way around a virtual city-block environment, experiencing two different kinds of optic flow as they went. By varying the rate at which the display was updated, we created optic flow that was either fluid or choppy. Here, fluid optic flow (as compared with choppy optic flow) enabled participants to locate a remembered target position more accurately. When other cues are unavailable, optic flow can be a significant aid in wayfinding. Among other things, optic flow can facilitate path integration, which involves updating a mental representation of place by combining the trajectories of previously travelled paths [corrected].

  8. Human Performance Assessments when Using Augmented Reality for Navigation

    DTIC Science & Technology

    2006-06-01

    Human performance executing search and rescue type of navigation is one area that can benefit from augmented reality technology when the proper...landmarks. We briefly report on an experiment that demonstrated the benefits of augmented reality in a search and rescue task. Specifically, 120...participants, equally divided by gender, were tested in speed and accuracy using augmented reality in a search and rescue task. Accuracy performance was

  9. Brain oscillatory activity during spatial navigation: theta and gamma activity link medial temporal and parietal regions.

    PubMed

    White, David J; Congedo, Marco; Ciorciari, Joseph; Silberstein, Richard B

    2012-03-01

    Brain oscillatory correlates of spatial navigation were investigated using blind source separation (BSS) and standardized low resolution electromagnetic tomography (sLORETA) analyses of 62-channel EEG recordings. Twenty-five participants were instructed to navigate to distinct landmark buildings in a previously learned virtual reality town environment. Data from periods of navigation between landmarks were subject to BSS analyses to obtain source components. Two of these cortical sources were found to exhibit significant spectral power differences during navigation with respect to a resting eyes open condition and were subject to source localization using sLORETA. These two sources were localized as a right parietal component with gamma activation and a right medial-temporal-parietal component with activation in theta and gamma bandwidths. The parietal gamma activity was thought to reflect visuospatial processing associated with the task. The medial-temporal-parietal activity was thought to be more specific to the navigational processing, representing the integration of ego- and allo-centric representations of space required for successful navigation, suggesting theta and gamma oscillations may have a role in integrating information from parietal and medial-temporal regions. Theta activity on this medial-temporal-parietal source was positively correlated with more efficient navigation performance. Results are discussed in light of the depth and proposed closed field structure of the hippocampus and potential implications for scalp EEG data. The findings of the present study suggest that appropriate BSS methods are ideally suited to minimizing the effects of volume conduction in noninvasive recordings, allowing more accurate exploration of deep brain processes.

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

    PubMed

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

    2015-06-01

    The ability to navigate without getting lost is an important aspect of quality of life. In 5 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 with 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 with degraded vision. With degraded vision, auditory task performance was better when guided compared with 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.

  11. 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

  12. Close but no cigar: Spatial precision deficits following medial temporal lobe lesions provide novel insight into theoretical models of navigation and memory.

    PubMed

    Kolarik, Branden S; Baer, Trevor; Shahlaie, Kiarash; Yonelinas, Andrew P; Ekstrom, Arne D

    2017-09-09

    Increasing evidence suggests that the human hippocampus contributes to a range of different behaviors, including episodic memory, language, short-term memory, and navigation. A novel theoretical framework, the Precision and Binding Model, accounts for these phenomenon by describing a role for the hippocampus in high-resolution, complex binding. Other theories like Cognitive Map Theory, in contrast, predict a specific role for the hippocampus in allocentric navigation, while Declarative Memory Theory predicts a specific role in delay-dependent conscious memory. Navigation provides a unique venue for testing these predictions, with past results from research with humans providing inconsistent findings regarding the role of the human hippocampus in spatial navigation. Here, we tested five patients with lesions primarily restricted to the hippocampus and those extending out into the surrounding medial temporal lobe cortex on a virtual water maze task. Consistent with the Precision and Binding Model, we found partially intact allocentric memory in all patients, with impairments in the spatial precision of their searches for a hidden target. We found similar impairments at both immediate and delayed testing. Our findings are consistent with the Precision and Binding Model of hippocampal function, arguing for its role across domains in high-resolution, complex binding. Remembering goal locations in one's environment is a critical skill for survival. How this information is represented in the brain is still not fully understood, but is believed to rely in some capacity on structures in the medial temporal lobe. Contradictory findings from studies of both humans and animals have been difficult to reconcile with regard to the role of the MTL, specifically the hippocampus. By assessing impairments observed during navigation to a goal in patients with medial temporal lobe damage we can better understand the role these structures play in such behavior. Utilizing virtual reality

  13. Natural Models for Autonomous Control of Spatial Navigation, Sensing, and Guidance, Part 1

    DTIC Science & Technology

    2011-06-16

    screening technique for polarization sensitivity in any animal (trialed on crustacean, cephalopods, fish and next turtles). b) Demonstration of...information transfer) in marine animals , with a view to using what we learn in technological applications. Spatial navigation, sensing and guidance are...tasks animals behaving in the real world accomplish every day and some of this is achieved using polarized light, a form of electromagnetic radiation

  14. Robotic magnetic navigation for ablation of human arrhythmias

    PubMed Central

    Da Costa, Antoine; Guichard, Jean Baptiste; Roméyer-Bouchard, Cécile; Gerbay, Antoine; Isaaz, Karl

    2016-01-01

    Radiofrequency treatment represents the first choice of treatment for arrhythmias, in particular complex arrhythmias and especially atrial fibrillation, due to the greater benefit/risk ratio compared to antiarrhythmic drugs. However, complex arrhythmias such as atrial fibrillation require long procedures with additional risks such as X-ray exposure or serious complications such as tamponade. Given this context, the treatment of arrhythmias using robotic magnetic navigation entails a technique well suited to complex arrhythmias on account of its efficacy, reliability, significant reduction in X-ray exposure for both patient and operator, as well as a very low risk of perforation. As ongoing developments will likely improve results and procedure times, this technology will become one of the most modern technologies for treating arrhythmias. Based on the literature, this review summarizes the advantages and limitations of robotic magnetic navigation for ablation of human arrhythmias. PMID:27698569

  15. Anticipatory control and spatial cognition in locomotion and navigation through typical development and in cerebral palsy.

    PubMed

    Belmonti, Vittorio; Cioni, Giovanni; Berthoz, Alain

    2016-03-01

    Behavioural evidence, summarized in this narrative review, supports a developmental model of locomotor control based on increasing neural integration of spatial reference frames. Two consistent adult locomotor behaviours are head stabilization and head anticipation: the head is stabilized to gravity and leads walking direction. This cephalocaudal orienting organization aligns gaze and vestibula with a reference frame centred on the upcoming walking direction, allowing anticipatory control on body kinematics, but is not fully developed until adolescence. Walking trajectories and those of hand movements share many aspects, including power laws coupling velocity to curvature, and minimized spatial variability. In fact, the adult brain can code trajectory geometry in an allocentric reference frame, irrespective of the end effector, regulating body kinematics thereafter. Locomotor trajectory formation, like head anticipation, matures in early adolescence, indicating common neurocomputational substrates. These late-developing control mechanisms can be distinguished from biomechanical problems in children with cerebral palsy (CP). Children's performance on a novel navigation test, the Magic Carpet, indicates that typical navigation development consists of the increasing integration of egocentric and allocentric reference frames. In CP, right-brain impairment seems to reduce navigation performance due to a maladaptive left-brain sequential egocentric strategy. Spatial integration should be considered more in rehabilitation. © 2016 The Authors. Developmental Medicine & Child Neurology © 2016 Mac Keith Press.

  16. A Bayesian nonparametric approach for uncovering rat hippocampal population codes during spatial navigation.

    PubMed

    Linderman, Scott W; Johnson, Matthew J; Wilson, Matthew A; Chen, Zhe

    2016-04-01

    Rodent hippocampal population codes represent important spatial information about the environment during navigation. Computational methods have been developed to uncover the neural representation of spatial topology embedded in rodent hippocampal ensemble spike activity. We extend our previous work and propose a novel Bayesian nonparametric approach to infer rat hippocampal population codes during spatial navigation. To tackle the model selection problem, we leverage a Bayesian nonparametric model. Specifically, we apply a hierarchical Dirichlet process-hidden Markov model (HDP-HMM) using two Bayesian inference methods, one based on Markov chain Monte Carlo (MCMC) and the other based on variational Bayes (VB). The effectiveness of our Bayesian approaches is demonstrated on recordings from a freely behaving rat navigating in an open field environment. The HDP-HMM outperforms the finite-state HMM in both simulated and experimental data. For HPD-HMM, the MCMC-based inference with Hamiltonian Monte Carlo (HMC) hyperparameter sampling is flexible and efficient, and outperforms VB and MCMC approaches with hyperparameters set by empirical Bayes. The Bayesian nonparametric HDP-HMM method can efficiently perform model selection and identify model parameters, which can used for modeling latent-state neuronal population dynamics. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. A nonparametric Bayesian approach for uncovering rat hippocampal population codes during spatial navigation

    PubMed Central

    Linderman, Scott W.; Johnson, Matthew J.; Wilson, Matthew A.; Chen, Zhe

    2016-01-01

    Background Rodent hippocampal population codes represent important spatial information about the environment during navigation. Computational methods have been developed to uncover the neural representation of spatial topology embedded in rodent hippocampal ensemble spike activity. New method We extend our previous work and propose a novel nonparametric Bayesian approach to infer rat hippocampal population codes during spatial navigation. To tackle the model selection problem, we leverage a nonparametric Bayesian model. Specifically, we apply a hierarchical Dirichlet process-hidden Markov model (HDP-HMM) using two Bayesian inference methods, one based on Markov chain Monte Carlo (MCMC) and the other based on variational Bayes (VB). Results The effectiveness of our Bayesian approaches is demonstrated on recordings from a freely-behaving rat navigating in an open field environment. Comparison with existing methods The HDP-HMM outperforms the finite-state HMM in both simulated and experimental data. For HPD-HMM, the MCMC-based inference with Hamiltonian Monte Carlo (HMC) hyperparameter sampling is flexible and efficient, and outperforms VB and MCMC approaches with hyperparameters set by empirical Bayes. Conclusion The nonparametric Bayesian HDP-HMM method can efficiently perform model selection and identify model parameters, which can used for modeling latent-state neuronal population dynamics. PMID:26854398

  18. 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…

  19. 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…

  20. Spatial Indexing of Datasets for CoreWall: CoreNavigator

    NASA Astrophysics Data System (ADS)

    Morin, P.; Jenkins, C.; Rao, A.; Kamp, B.; Higgins, S.; Ito, E.; Johnson, A.

    2006-12-01

    Corewall is a community computing facility for logging ice, lake, sediment and hard rock cores. It is described as a Collaborative Interactive Core Analysis Environment, allowing dispersed (even international and ship-side / in-the-field) logging and interpretation on sections of core representing Earth history. Many institutions support Corewall, including NSF. CoreNavigator is a 3D Visual Indexer of core and stratigraphic datasets, necessary because GIS systems available to researchers do not adequately display the vertical stratigraphic structure, or let users browse at will through the stratigraphy. CoreNavigator including its Google Earth extension, is likely to be a primary point of entry for the community into CoreWall. By a combination of 3D VRML and KML visualization technologies CoreNavigator indexes thousands of cores for user selection leading to a variety of actions. By clicking on visual 3D elements of CoreNavigator, users can obtain tables of integrated ready-to-use data (e.g., from dbSEABED, see web). They can also drill down into the original field notes, core photos, equipment types, lab analysis files, calibrations, etc. They can launch applications including the Corelyzer part of Corewall. [CoreNavigator 3D VRML displays are also editable and publishable, and can have seismic, oceanography, culture objects inserted. In the Geowall environment they are a resource for education.] CoreNavigator will be demonstrated as part of Corewall. By adopting a single spatial - global approach in this way to all types of cored stratigraphic data - ice, sediment, rock sea and lake - researchers will be able to transfer their enquiries and validation exercises in questions of environmental change, across the whole Earth surface.

  1. Can active navigation be as good as driving? A comparison of spatial memory in drivers and backseat drivers.

    PubMed

    von Stülpnagel, Rul; Steffens, Melanie C

    2012-06-01

    When driving a vehicle, either the driver or a passenger (henceforth: backseat driver) may be responsible for navigation. Research on active navigation, primarily addressed in virtual environments, suggests that controlling navigation is more central for spatial learning than controlling movement. To test this assumption in a real-world scenario, we manipulated movement control through seating participants in the front or the back position of a tandem bike, and navigation control by presenting differently detailed maps to participants unfamiliar (Experiment 1) or familiar (Experiment 2) with an environment. Landmark knowledge was tested with recognition tasks. For participants unfamiliar with the environment (Experiment 1), passive navigation enabled better landmark recognition than active navigation, but there was no effect of movement control. For participants more familiar with the environment (Experiment 2), there was no effect of navigation control, but drivers showed better landmark recognition than backseat drivers. These findings are discussed in relation to action memory research. Measures of route and survey knowledge demonstrated that good performance resulted from active navigation (Experiment 1-2). Moreover, with regard to these measures, driving compensated for passive navigation if the environment was familiar (Experiment 2). An additional experiment in a lab setting (Experiment 3) validated the manipulation of navigation control and the used tasks and demonstrated the importance of real environment exposure. As our findings suggest, driving may be more relevant for remembering landmarks, but actively controlling navigation (even as a backseat driver) is more relevant for remembering a route than maneuvering a vehicle.

  2. Spatial cognition and neuro-mimetic navigation: a model of hippocampal place cell activity.

    PubMed

    Arleo, A; Gerstner, W

    2000-09-01

    A computational model of hippocampal activity during spatial cognition and navigation tasks is presented. The spatial representation in our model of the rat hippocampus is built on-line during exploration via two processing streams. An allothetic vision-based representation is built by unsupervised Hebbian learning extracting spatio-temporal properties of the environment from visual input. An idiothetic representation is learned based on internal movement-related information provided by path integration. On the level of the hippocampus, allothetic and idiothetic representations are integrated to yield a stable representation of the environment by a population of localized overlapping CA3-CA1 place fields. The hippocampal spatial representation is used as a basis for goal-oriented spatial behavior. We focus on the neural pathway connecting the hippocampus to the nucleus accumbens. Place cells drive a population of locomotor action neurons in the nucleus accumbens. Reward-based learning is applied to map place cell activity into action cell activity. The ensemble action cell activity provides navigational maps to support spatial behavior. We present experimental results obtained with a mobile Khepera robot.

  3. Beyond Dizziness: Virtual Navigation, Spatial Anxiety and Hippocampal Volume in Bilateral Vestibulopathy.

    PubMed

    Kremmyda, Olympia; Hüfner, Katharina; Flanagin, Virginia L; Hamilton, Derek A; Linn, Jennifer; Strupp, Michael; Jahn, Klaus; Brandt, Thomas

    2016-01-01

    Bilateral vestibulopathy (BVP) is defined as the impairment or loss of function of either the labyrinths or the eighth nerves. Patients with total BVP due to bilateral vestibular nerve section exhibit difficulties in spatial memory and navigation and show a loss of hippocampal volume. In clinical practice, most patients do not have a complete loss of function but rather an asymmetrical residual functioning of the vestibular system. The purpose of the current study was to investigate navigational ability and hippocampal atrophy in BVP patients with residual vestibular function. Fifteen patients with BVP and a group of age- and gender- matched healthy controls were examined. Self-reported questionnaires on spatial anxiety and wayfinding were used to assess the applied strategy of wayfinding and quality of life. Spatial memory and navigation were tested directly using a virtual Morris Water Maze Task. The hippocampal volume of these two groups was evaluated by voxel-based morphometry. In the patients, the questionnaire showed a higher spatial anxiety and the Morris Water Maze Task a delayed spatial learning performance. MRI revealed a significant decrease in the gray matter mid-hippocampal volume (Left: p = 0.006, Z = 4.58, Right: p < 0.001, Z = 3.63) and posterior parahippocampal volume (Right: p = 0.005, Z = 4.65, Left: p < 0.001, Z = 3.87) compared to those of healthy controls. In addition, a decrease in hippocampal formation volume correlated with a more dominant route-finding strategy. Our current findings demonstrate that even partial bilateral vestibular loss leads to anatomical and functional changes in the hippocampal formation and objective and subjective behavioral deficits.

  4. Beyond Dizziness: Virtual Navigation, Spatial Anxiety and Hippocampal Volume in Bilateral Vestibulopathy

    PubMed Central

    Kremmyda, Olympia; Hüfner, Katharina; Flanagin, Virginia L.; Hamilton, Derek A.; Linn, Jennifer; Strupp, Michael; Jahn, Klaus; Brandt, Thomas

    2016-01-01

    Bilateral vestibulopathy (BVP) is defined as the impairment or loss of function of either the labyrinths or the eighth nerves. Patients with total BVP due to bilateral vestibular nerve section exhibit difficulties in spatial memory and navigation and show a loss of hippocampal volume. In clinical practice, most patients do not have a complete loss of function but rather an asymmetrical residual functioning of the vestibular system. The purpose of the current study was to investigate navigational ability and hippocampal atrophy in BVP patients with residual vestibular function. Fifteen patients with BVP and a group of age- and gender- matched healthy controls were examined. Self-reported questionnaires on spatial anxiety and wayfinding were used to assess the applied strategy of wayfinding and quality of life. Spatial memory and navigation were tested directly using a virtual Morris Water Maze Task. The hippocampal volume of these two groups was evaluated by voxel-based morphometry. In the patients, the questionnaire showed a higher spatial anxiety and the Morris Water Maze Task a delayed spatial learning performance. MRI revealed a significant decrease in the gray matter mid-hippocampal volume (Left: p = 0.006, Z = 4.58, Right: p < 0.001, Z = 3.63) and posterior parahippocampal volume (Right: p = 0.005, Z = 4.65, Left: p < 0.001, Z = 3.87) compared to those of healthy controls. In addition, a decrease in hippocampal formation volume correlated with a more dominant route-finding strategy. Our current findings demonstrate that even partial bilateral vestibular loss leads to anatomical and functional changes in the hippocampal formation and objective and subjective behavioral deficits. PMID:27065838

  5. 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

  6. The Developmental Trajectory of Intramaze and Extramaze Landmark Biases in Spatial Navigation: An Unexpected Journey

    PubMed Central

    2015-01-01

    Adults learning to navigate to a hidden goal within an enclosed space have been found to prefer information provided by the distal cues of an environment, as opposed to proximal landmarks within the environment. Studies with children, however, have shown that 5- or 7-year-olds do not display any preference toward distal or proximal cues during navigation. This suggests that a bias toward learning about distal cues occurs somewhere between the age of 7 years and adulthood. We recruited 5- to 11-year-old children and an adult sample to explore the developmental profile of this putative change. Across a series of 3 experiments, participants were required to navigate to a hidden goal in a virtual environment, the location of which was signaled by both extramaze and intramaze landmark cues. During testing, these cues were placed into conflict to assess the search preferences of participants. Consistent with previously reported findings, adults were biased toward using extramaze information. However, analysis of the data from children, which incorporated age as a continuous variable, suggested that older children in our sample were, in fact, biased toward using the intramaze landmark in our task. These findings suggest the bias toward using distal cues in spatial navigation, frequently displayed by adults, may be a comparatively late developing trait, and one that could supersede an initial developmental preference for proximal landmarks. PMID:25844850

  7. Variants of the Morris water maze task to comparatively assess human and rodent place navigation.

    PubMed

    Schoenfeld, Robby; Schiffelholz, Thomas; Beyer, Christian; Leplow, Bernd; Foreman, Nigel

    2017-03-01

    Performance in the Morris water maze has been widely used in routine behavioural studies of rodents. Since the advent of computer-based virtual environments, adaptations of the water maze have become available for human research. Despite decades of comparative neuroscience, formal comparisons of human and animal place navigation performance are rare. We studied 36 subjects, 18 young male mice in a Morris water maze and 18 male students in a virtual version. Quantitative measures (escape latencies, distances and platform crossings) indicated no discernable differences between human and rodent performance, reinforcing the task's general validity and its implied cross-species comparability. However, we extracted, using an a priori free classification method, qualitatively different movement patterns for mice and humans, patterns that reflect the probable strategy that individuals might have been using to solve the task. Our results indicated young male students to have most likely solved the maze by means of spatial strategies whereas mice were observed more often to have adopted non-spatial strategies. These differences could be attributed to differences in our maze setups (spatial cues, task instruction, training protocol, motivation) and gave further hints that maze learning depends on many factors. In summary performance on both spatial tasks was equivalent in humans and mice but the kind of maze learning that was used to achieve maximum performance was different.

  8. 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.

  9. 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

  10. 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.

  11. Dopamine modulation of spatial navigation memory in Parkinson's disease.

    PubMed

    Thurm, Franka; Schuck, Nicolas W; Fauser, Mareike; Doeller, Christian F; Stankevich, Yuliya; Evens, Ricarda; Riedel, Oliver; Storch, Alexander; Lueken, Ulrike; Li, Shu-Chen

    2016-02-01

    Striatal dopamine depletion is a key pathophysiological feature of Parkinson's disease (PD) causing motor and nonmotor symptoms. Research on nonmotor symptoms has mainly focused on frontostriatal functions. However, dopamine pathways ascending from the ventral tegmental area also innervate hippocampal structures and modulate hippocampal-dependent functions, such as spatial memory. Using a virtual spatial navigation task, we investigated dopaminergic modulation of spatial memory in PD patients in a crossover medication ON/OFF design. We examined medication effects on striatal- and hippocampal-dependent spatial memory by either replacing a location cue in the environment or enlarging its spatial boundary. Key results indicate that in contrast to prior evidence for younger adults, PD patients, like their age-matched controls, rely more on striatal cue-based than hippocampal spatial learning. Medication facilitated striatal-dependent cue-location learning, whereas medication benefit in hippocampal boundary-related spatial memory depended on prior experience with the task. Medication effects on spatial memory were comparable to and independent of benefits on motor symptoms. These findings shed new light on dopaminergic modulation of hippocampal-striatal functions in PD.

  12. The Influence of Spatial Familiarity on the Landmark Salience Sensibility in Pedestrian Navigation Environment

    NASA Astrophysics Data System (ADS)

    Li, X.,; Wu, X.-Q.; Yin, Z.-H.; Shen, J.

    2017-09-01

    To contribute to a more effective design of landmark navigation guidance, this paper is concerned with the relationship between the spatial familiarity and landmark salience, which includes visual, semantic and structural attributes. The link of those two is the subjective judgment of users, which is called landmark salience sensibility. In order to explore the influence of spatial familiarity on the landmark salience sensibility, we selected two types of experimental area including campus and commercial district and four groups of experimental subject with different spatial familiarity degree. After the whole walking process, subjects are asked to draw a navigation sketch for themselves. Depending on the landmarks remaining in the sketch, we calculated the three attributes of the mean landmark salience to represent the landmark salience sensibility of each group for both paths. The result shows that with the increase of spatial familiarity, the landmark salience sensitivity is gradually reduced and the ascending order of attention degree to the attributes of the landmark salience is visual, semantic and structural salience. This conclusion is supportive to the study of landmark extraction and pedestrian guidance. Because the outdoor landmarks are analysed, we propose that in the future indoor landmarks are needed to be concerned.

  13. Synergistic effects of dopamine D2-like receptor antagonist sulpiride and β-blocker propranolol on learning in the carousel maze, a dry-land spatial navigation task.

    PubMed

    Prokopova, Iva; Bahnik, Stepan; Doulames, Vanessa; Vales, Karel; Petrasek, Tomas; Svoboda, Jan; Stuchlik, Ales

    2012-07-01

    Spatial navigation attracts the attention of neuroscientists as an animal analogue of human declarative memory. The Carousel maze is a dry-land navigational paradigm, which proved to be useful in studying neurobiological substrates of learning. The task involves avoidance of a stable sector on a rotating arena and is highly dependent upon the hippocampus. The present study aims at testing hypothesis that sulpiride (a centrally-active dopamine D2-like receptor antagonist) and propranolol (a beta-blocker) impair spatial learning in the Carousel maze after combined systemic administration. These doses were previously shown to be subthreshold in this task. Results showed that both substances affected behavior and significantly potentiated their negative effects on spatial learning. This suggests central interaction of both types of receptors in influencing acquisition of this dynamic-environment task. Copyright © 2012 Elsevier Inc. All rights reserved.

  14. Human Factors Considerations for Area Navigation Departure and Arrival Procedures

    NASA Technical Reports Server (NTRS)

    Barhydt, Richard; Adams, Catherine A.

    2006-01-01

    Area navigation (RNAV) procedures are being implemented in the United States and around the world as part of a transition to a performance-based navigation system. These procedures are providing significant benefits and have also caused some human factors issues to emerge. Under sponsorship from the Federal Aviation Administration (FAA), the National Aeronautics and Space Administration (NASA) has undertaken a project to document RNAV-related human factors issues and propose areas for further consideration. The component focusing on RNAV Departure and Arrival Procedures involved discussions with expert users, a literature review, and a focused review of the NASA Aviation Safety Reporting System (ASRS) database. Issues were found to include aspects of air traffic control and airline procedures, aircraft systems, and procedure design. Major findings suggest the need for specific instrument procedure design guidelines that consider the effects of human performance. Ongoing industry and government activities to address air-ground communication terminology, design improvements, and chart-database commonality are strongly encouraged. A review of factors contributing to RNAV in-service errors would likely lead to improved system design and operational performance.

  15. 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.

  16. The role of the hippocampus in navigation is memory.

    PubMed

    Eichenbaum, Howard

    2017-04-01

    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. Copyright © 2017 the American Physiological Society.

  17. Working memory and reference memory tests of spatial navigation in mice (Mus musculus).

    PubMed

    Lee, Sang Ah; Tucci, Valter; Sovrano, Valeria Anna; Vallortigara, Giorgio

    2015-05-01

    Researchers in spatial cognition have debated for decades the specificity of the mechanisms through which spatial information is processed and stored. Interestingly, although rodents are the preferred animal model for studying spatial navigation, the behavioral methods traditionally used to assess spatial memory do not effectively test the predictions of specificity in their representation. To address such issues, the present study tested the ability of mice to use boundary geometry and features to remember a goal location across 2 types of tasks--a working memory task with a changing goal location, and a reference memory task with 1 rewarded goal location. We show for the first time that mice, like other animals, can successfully encode boundary geometry in a working memory spatial mapping task, just as they do in a reference memory task. Their use of a nongeometric featural cue (striped pattern), in contrast, was more limited in the working memory task, although it quickly improved in the reference memory task. We discuss the implications of these findings for future research on the neural and genetic underpinnings of spatial representations.

  18. Computational cognitive models of spatial memory in navigation space: a review.

    PubMed

    Madl, Tamas; Chen, Ke; Montaldi, Daniela; Trappl, Robert

    2015-05-01

    Spatial memory refers to the part of the memory system that encodes, stores, recognizes and recalls spatial information about the environment and the agent's orientation within it. Such information is required to be able to navigate to goal locations, and is vitally important for any embodied agent, or model thereof, for reaching goals in a spatially extended environment. In this paper, a number of computationally implemented cognitive models of spatial memory are reviewed and compared. Three categories of models are considered: symbolic models, neural network models, and models that are part of a systems-level cognitive architecture. Representative models from each category are described and compared in a number of dimensions along which simulation models can differ (level of modeling, types of representation, structural accuracy, generality and abstraction, environment complexity), including their possible mapping to the underlying neural substrate. Neural mappings are rarely explicated in the context of behaviorally validated models, but they could be useful to cognitive modeling research by providing a new approach for investigating a model's plausibility. Finally, suggested experimental neuroscience methods are described for verifying the biological plausibility of computational cognitive models of spatial memory, and open questions for the field of spatial memory modeling are outlined.

  19. The traveling salesrat: insights into the dynamics of efficient spatial navigation in the rodent

    NASA Astrophysics Data System (ADS)

    Watkins de Jong, Laurel; Gereke, Brian; Martin, Gerard M.; Fellous, Jean-Marc

    2011-10-01

    Rodent spatial navigation requires the dynamic evaluation of multiple sources of information, including visual cues, self-motion signals and reward signals. The nature of the evaluation, its dynamics and the relative weighting of the multiple information streams are largely unknown and have generated many hypotheses in the field of robotics. We use the framework of the traveling salesperson problem (TSP) to study how this evaluation may be achieved. The TSP is a classical artificial intelligence NP-hard problem that requires an agent to visit a fixed set of locations once, minimizing the total distance traveled. We show that after a few trials, rats converge on a short route between rewarded food cups. We propose that this route emerges from a series of local decisions that are derived from weighing information embedded in the context of the task. We study the relative weighting of spatial and reward information and establish that, in the conditions of this experiment, when the contingencies are not in conflict, rats choose the spatial or reward optimal solution. There was a trend toward a preference for space when the contingencies were in conflict. We also show that the spatial decision about which cup to go to next is biased by the orientation of the animal. Reward contingencies are also shown to significantly and dynamically modulate the decision-making process. This paradigm will allow for further neurophysiological studies aimed at understanding the synergistic role of brain areas involved in planning, reward processing and spatial navigation. These insights will in turn suggest new neural-like architectures for the control of mobile autonomous robots.

  20. The traveling salesrat: insights into the dynamics of efficient spatial navigation in the rodent.

    PubMed

    de Jong, Laurel Watkins; Gereke, Brian; Martin, Gerard M; Fellous, Jean-Marc

    2011-12-01

    Rodent spatial navigation requires the dynamic evaluation of multiple sources of information, including visual cues, self-motion signals and reward signals. The nature of the evaluation, its dynamics and the relative weighting of the multiple information streams are largely unknown and have generated many hypotheses in the field of robotics. We use the framework of the traveling salesperson problem (TSP) to study how this evaluation may be achieved. The TSP is a classical artificial intelligence NP-hard problem that requires an agent to visit a fixed set of locations once, minimizing the total distance traveled. We show that after a few trials, rats converge on a short route between rewarded food cups. We propose that this route emerges from a series of local decisions that are derived from weighing information embedded in the context of the task. We study the relative weighting of spatial and reward information and establish that, in the conditions of this experiment, when the contingencies are not in conflict, rats choose the spatial or reward optimal solution. There was a trend toward a preference for space when the contingencies were in conflict. We also show that the spatial decision about which cup to go to next is biased by the orientation of the animal. Reward contingencies are also shown to significantly and dynamically modulate the decision-making process. This paradigm will allow for further neurophysiological studies aimed at understanding the synergistic role of brain areas involved in planning, reward processing and spatial navigation. These insights will in turn suggest new neural-like architectures for the control of mobile autonomous robots.

  1. 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.

  2. Does spatial information impact immediate verbatim recall of verbal navigation instructions?

    PubMed

    Schneider, Vivian I; Healy, Alice F; Kole, James A; Barshi, Immanuel

    2017-09-25

    The present study addresses the issue of whether spatial information impacts immediate verbatim recall of verbal navigation instructions. Subjects heard messages instructing them to move within a two-dimensional depiction of a three-dimensional space consisting of four stacked grids displayed on a computer screen. They repeated the instructions orally and then followed them manually by clicking with a mouse on the grids. Two groups with identical instructions were compared; they differed only in whether the starting position was indicated before or after the instructions were given and repeated, with no differences in the manual movements to be made. Accuracy on both the oral repetition and manual movement responses was significantly higher when the starting position was indicated before the instructions. The results are consistent with the proposal that there is only a single amodal mental representation, rather than distinct verbal and nonverbal representations, of navigation instructions. The advantage for the before condition was found even for the oral repetition responses, implying that the creation of the amodal representation occurred immediately, while the instructions were being held in working memory. In practical terms, the findings imply that being able to form a mental representation of the movement path while being given verbal navigation instructions should substantially facilitate memory for the instructions and execution of them.

  3. 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

  4. The effect of contextual auditory stimuli on virtual spatial navigation in patients with focal hemispheric lesions.

    PubMed

    Cogné, Mélanie; Knebel, Jean-François; Klinger, Evelyne; Bindschaedler, Claire; Rapin, Pierre-André; Joseph, Pierre-Alain; Clarke, Stephanie

    2016-01-06

    Topographical disorientation is a frequent deficit among patients suffering from brain injury. Spatial navigation can be explored in this population using virtual reality environments, even in the presence of motor or sensory disorders. Furthermore, the positive or negative impact of specific stimuli can be investigated. We studied how auditory stimuli influence the performance of brain-injured patients in a navigational task, using the Virtual Action Planning-Supermarket (VAP-S) with the addition of contextual ("sonar effect" and "name of product") and non-contextual ("periodic randomised noises") auditory stimuli. The study included 22 patients with a first unilateral hemispheric brain lesion and 17 healthy age-matched control subjects. After a software familiarisation, all subjects were tested without auditory stimuli, with a sonar effect or periodic random sounds in a random order, and with the stimulus "name of product". Contextual auditory stimuli improved patient performance more than control group performance. Contextual stimuli benefited most patients with severe executive dysfunction or with severe unilateral neglect. These results indicate that contextual auditory stimuli are useful in the assessment of navigational abilities in brain-damaged patients and that they should be used in rehabilitation paradigms.

  5. 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.

  6. Mental "Space" Travel: Damage to Posterior Parietal Cortex Prevents Egocentric Navigation and Reexperiencing of Remote Spatial Memories

    ERIC Educational Resources Information Center

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

    2010-01-01

    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…

  7. Mental "Space" Travel: Damage to Posterior Parietal Cortex Prevents Egocentric Navigation and Reexperiencing of Remote Spatial Memories

    ERIC Educational Resources Information Center

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

    2010-01-01

    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…

  8. 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.

  9. Spatial Evolution of Human Dialects

    NASA Astrophysics Data System (ADS)

    Burridge, James

    2017-07-01

    The geographical pattern of human dialects is a result of history. Here, we formulate a simple spatial model of language change which shows that the final result of this historical evolution may, to some extent, be predictable. The model shows that the boundaries of language dialect regions are controlled by a length minimizing effect analogous to surface tension, mediated by variations in population density which can induce curvature, and by the shape of coastline or similar borders. The predictability of dialect regions arises because these effects will drive many complex, randomized early states toward one of a smaller number of stable final configurations. The model is able to reproduce observations and predictions of dialectologists. These include dialect continua, isogloss bundling, fanning, the wavelike spread of dialect features from cities, and the impact of human movement on the number of dialects that an area can support. The model also provides an analytical form for Séguy's curve giving the relationship between geographical and linguistic distance, and a generalization of the curve to account for the presence of a population center. A simple modification allows us to analytically characterize the variation of language use by age in an area undergoing linguistic change.

  10. Using hippocampal-striatal loops for spatial navigation and goal-directed decision-making.

    PubMed

    Chersi, Fabian; Pezzulo, Giovanni

    2012-08-01

    The hippocampus plays a central role in spatial representation, declarative and episodic memory. In this area, so-called place cells possess high spatial selectivity, firing preferentially when the individual is within a small area of the environment. Interestingly, it has been found in rats that these cells can be active also when the animal is outside the location or context of their corresponding place field producing so-called "forward sweeps". These typically occur at decision points during task execution and seem to be utilized, among other things, for the evaluation of potential alternative paths. Anticipatory firing is also found in the ventral striatum, a brain area that is strongly interconnected with the hippocampus and is known to encode value and reward. In this paper, we describe a biologically based computational model of the hippocampal-ventral striatum circuit that implements a goal-directed mechanism of choice, with the hippocampus primarily involved in the mental simulation of possible navigation paths and the ventral striatum involved in the evaluation of the associated reward expectancies. The model is validated in a navigation task in which a rat is placed in a complex maze with multiple rewarding sites. We show that the rat mentally activates place cells to simulate paths, estimate their value, and make decisions, implementing two essential processes of model-based reinforcement learning algorithms of choice: look-ahead prediction and the evaluation of predicted states.

  11. 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.

  12. Dietary Polyphenol Supplementation Prevents Alterations of Spatial Navigation in Middle-Aged Mice

    PubMed Central

    Bensalem, Julien; Servant, Laure; Alfos, Serge; Gaudout, David; Layé, Sophie; Pallet, Véronique; Lafenetre, Pauline

    2016-01-01

    Spatial learning and memory deficits associated with hippocampal synaptic plasticity impairments are commonly observed during aging. Besides, the beneficial role of dietary polyphenols has been suggested as potential functional food candidates to prevent this memory decline. Indeed, polyphenols could potentiate the signaling pathways of synaptic plasticity underlying learning and memory. In this study, spatial learning deficits of middle-aged mice were first highlighted and characterized according to their navigation patterns in the Morris water maze task. An eight-week polyphenol-enriched diet, containing a polyphenol-rich extract from grape and blueberry (PEGB; from the Neurophenols Consortium) with high contents of flavonoids, stilbenes and phenolic acids, was then successful in reversing these age-induced effects. The use of spatial strategies was indeed delayed with aging whereas a polyphenol supplementation could promote the occurrence of spatial strategies. These behavioral results were associated with neurobiological changes: while the expression of hippocampal calmodulin kinase II (CaMKII) mRNA levels was reduced in middle-aged animals, the polyphenol-enriched diet could rescue them. Besides, an increased expression of nerve growth neurotrophic factor (NGF) mRNA levels was also observed in supplemented adult and middle-aged mice. Thus these data suggest that supplementation with polyphenols could be an efficient nutritional way to prevent age-induced cognitive decline. PMID:26903826

  13. Dietary Polyphenol Supplementation Prevents Alterations of Spatial Navigation in Middle-Aged Mice.

    PubMed

    Bensalem, Julien; Servant, Laure; Alfos, Serge; Gaudout, David; Layé, Sophie; Pallet, Véronique; Lafenetre, Pauline

    2016-01-01

    Spatial learning and memory deficits associated with hippocampal synaptic plasticity impairments are commonly observed during aging. Besides, the beneficial role of dietary polyphenols has been suggested as potential functional food candidates to prevent this memory decline. Indeed, polyphenols could potentiate the signaling pathways of synaptic plasticity underlying learning and memory. In this study, spatial learning deficits of middle-aged mice were first highlighted and characterized according to their navigation patterns in the Morris water maze task. An eight-week polyphenol-enriched diet, containing a polyphenol-rich extract from grape and blueberry (PEGB; from the Neurophenols Consortium) with high contents of flavonoids, stilbenes and phenolic acids, was then successful in reversing these age-induced effects. The use of spatial strategies was indeed delayed with aging whereas a polyphenol supplementation could promote the occurrence of spatial strategies. These behavioral results were associated with neurobiological changes: while the expression of hippocampal calmodulin kinase II (CaMKII) mRNA levels was reduced in middle-aged animals, the polyphenol-enriched diet could rescue them. Besides, an increased expression of nerve growth neurotrophic factor (NGF) mRNA levels was also observed in supplemented adult and middle-aged mice. Thus these data suggest that supplementation with polyphenols could be an efficient nutritional way to prevent age-induced cognitive decline.

  14. The role of spatial abilities and age in performance in an auditory computer navigation task.

    PubMed

    Pak, Richard; Czaja, Sara J; Sharit, Joseph; Rogers, Wendy A; Fisk, Arthur D

    2006-01-01

    Age-related differences in spatial ability have been suggested as a mediator of age-related differences in computer-based task performance. However, the vast majority of tasks studied have primarily used a visual display (e.g., graphical user interfaces). In the current study, the relationship between spatial ability and performance in a non-visual computer-based navigation task was examined in a sample of 196 participants ranging in age from 18 to 91. Participants called into a simulated interactive voice response system and carried out a variety of transactions. They also completed measures of attention, working memory, and spatial abilities. The results showed that age-related differences in spatial ability predicted a significant amount of variance in performance in the non-visual computer task, even after controlling for other abilities. Understanding the abilities that influence performance with technology may provide insight into the source of age-related performance differences in the successful use of technology.

  15. The role of spatial abilities and age in performance in an auditory computer navigation task

    PubMed Central

    Pak, Richard; Czaja, Sara J.; Sharit, Joseph; Rogers, Wendy A.; Fisk, Arthur D.

    2008-01-01

    Age-related differences in spatial ability have been suggested as a mediator of age-related differences in computer-based task performance. However, the vast majority of tasks studied have primarily used a visual display (e.g., graphical user interfaces). In the current study, the relationship between spatial ability and performance in a non-visual computer-based navigation task was examined in a sample of 196 participants ranging in age from 18 to 91. Participants called into a simulated interactive voice response system and carried out a variety of transactions. They also completed measures of attention, working memory, and spatial abilities. The results showed that age-related differences in spatial ability predicted a significant amount of variance in performance in the non-visual computer task, even after controlling for other abilities. Understanding the abilities that influence performance with technology may provide insight into the source of age-related performance differences in the successful use of technology. PMID:18997876

  16. An electrophysiological correlate of conflict processing in an auditory spatial Stroop task: the effect of individual differences in navigational style.

    PubMed

    Buzzell, George A; Roberts, Daniel M; Baldwin, Carryl L; McDonald, Craig G

    2013-11-01

    Recent work has identified an event-related potential (ERP) component, the incongruency negativity (N(inc)), which is sensitive to auditory Stroop conflict processing. Here, we investigated how this index of conflict processing is influenced by individual differences in cognitive style. There is evidence that individuals differ in the strategy they use to navigate through the environment; some use a predominantly verbal-egocentric strategy while others rely more heavily on a spatial-allocentric strategy. In addition, navigational strategy, assessed by a way-finding questionnaire, is predictive of performance on an auditory spatial Stroop task, in which either the semantic or spatial dimension of stimuli must be ignored. To explore the influence of individual differences in navigational style on conflict processing, participants took part in an auditory spatial Stroop task while the electroencephalogram (EEG) was recorded. Whereas behavioral performance only showed a main effect of congruency, we observed the predicted three-way interaction between congruency, task type and navigational style with respect to our physiological measure of Stroop conflict. Specifically, congruency-dependent modulation of the N(inc) was observed only when participants performed their non-dominant task (e.g., verbal navigators attempting to ignore semantic information). These results confirm that the N(inc) reliably indexes auditory Stroop conflict and extend previous results by demonstrating that the N(inc) is predictably modulated by individual differences in cognitive style. © 2013.

  17. Using ontologies to model human navigation behavior in information networks: A study based on Wikipedia.

    PubMed

    Lamprecht, Daniel; Strohmaier, Markus; Helic, Denis; Nyulas, Csongor; Tudorache, Tania; Noy, Natalya F; Musen, Mark A

    The need to examine the behavior of different user groups is a fundamental requirement when building information systems. In this paper, we present Ontology-based Decentralized Search (OBDS), a novel method to model the navigation behavior of users equipped with different types of background knowledge. Ontology-based Decentralized Search combines decentralized search, an established method for navigation in social networks, and ontologies to model navigation behavior in information networks. The method uses ontologies as an explicit representation of background knowledge to inform the navigation process and guide it towards navigation targets. By using different ontologies, users equipped with different types of background knowledge can be represented. We demonstrate our method using four biomedical ontologies and their associated Wikipedia articles. We compare our simulation results with base line approaches and with results obtained from a user study. We find that our method produces click paths that have properties similar to those originating from human navigators. The results suggest that our method can be used to model human navigation behavior in systems that are based on information networks, such as Wikipedia. This paper makes the following contributions: (i) To the best of our knowledge, this is the first work to demonstrate the utility of ontologies in modeling human navigation and (ii) it yields new insights and understanding about the mechanisms of human navigation in information networks.

  18. Using ontologies to model human navigation behavior in information networks: A study based on Wikipedia

    PubMed Central

    Lamprecht, Daniel; Strohmaier, Markus; Helic, Denis; Nyulas, Csongor; Tudorache, Tania; Noy, Natalya F.; Musen, Mark A.

    2015-01-01

    The need to examine the behavior of different user groups is a fundamental requirement when building information systems. In this paper, we present Ontology-based Decentralized Search (OBDS), a novel method to model the navigation behavior of users equipped with different types of background knowledge. Ontology-based Decentralized Search combines decentralized search, an established method for navigation in social networks, and ontologies to model navigation behavior in information networks. The method uses ontologies as an explicit representation of background knowledge to inform the navigation process and guide it towards navigation targets. By using different ontologies, users equipped with different types of background knowledge can be represented. We demonstrate our method using four biomedical ontologies and their associated Wikipedia articles. We compare our simulation results with base line approaches and with results obtained from a user study. We find that our method produces click paths that have properties similar to those originating from human navigators. The results suggest that our method can be used to model human navigation behavior in systems that are based on information networks, such as Wikipedia. This paper makes the following contributions: (i) To the best of our knowledge, this is the first work to demonstrate the utility of ontologies in modeling human navigation and (ii) it yields new insights and understanding about the mechanisms of human navigation in information networks. PMID:26568745

  19. Principles of goal-directed spatial robot navigation in biomimetic models

    PubMed Central

    Milford, Michael; Schulz, Ruth

    2014-01-01

    Mobile robots and animals alike must effectively navigate their environments in order to achieve their goals. For animals goal-directed navigation facilitates finding food, seeking shelter or migration; similarly robots perform goal-directed navigation to find a charging station, get out of the rain or guide a person to a destination. This similarity in tasks extends to the environment as well; increasingly, mobile robots are operating in the same underwater, ground and aerial environments that animals do. Yet despite these similarities, goal-directed navigation research in robotics and biology has proceeded largely in parallel, linked only by a small amount of interdisciplinary research spanning both areas. Most state-of-the-art robotic navigation systems employ a range of sensors, world representations and navigation algorithms that seem far removed from what we know of how animals navigate; their navigation systems are shaped by key principles of navigation in ‘real-world’ environments including dealing with uncertainty in sensing, landmark observation and world modelling. By contrast, biomimetic animal navigation models produce plausible animal navigation behaviour in a range of laboratory experimental navigation paradigms, typically without addressing many of these robotic navigation principles. In this paper, we attempt to link robotics and biology by reviewing the current state of the art in conventional and biomimetic goal-directed navigation models, focusing on the key principles of goal-oriented robotic navigation and the extent to which these principles have been adapted by biomimetic navigation models and why. PMID:25267826

  20. Effects of developmental exposure to bisphenol A on spatial navigational learning and memory in rats: A CLARITY-BPA study.

    PubMed

    Johnson, Sarah A; Javurek, Angela B; Painter, Michele S; Ellersieck, Mark R; Welsh, Thomas H; Camacho, Luísa; Lewis, Sherry M; Vanlandingham, Michelle M; Ferguson, Sherry A; Rosenfeld, Cheryl S

    2016-04-01

    Bisphenol A (BPA) is a ubiquitous industrial chemical used in the production of a wide variety of items. Previous studies suggest BPA exposure may result in neuro-disruptive effects; however, data are inconsistent across animal and human studies. As part of the Consortium Linking Academic and Regulatory Insights on BPA Toxicity (CLARITY-BPA), we sought to determine whether female and male rats developmentally exposed to BPA demonstrated later spatial navigational learning and memory deficits. Pregnant NCTR Sprague-Dawley rats were orally dosed from gestational day 6 to parturition, and offspring were directly orally dosed until weaning (postnatal day 21). Treatment groups included a vehicle control, three BPA doses (2.5μg/kg body weight (bw)/day-[2.5], 25μg/kg bw/day-[25], and 2500μg/kg bw/day-[2500]) and a 0.5μg/kg/day ethinyl estradiol (EE)-reference estrogen dose. At adulthood, 1/sex/litter was tested for seven days in the Barnes maze. The 2500 BPA group sniffed more incorrect holes on day 7 than those in the control, 2.5 BPA, and EE groups. The 2500 BPA females were less likely than control females to locate the escape box in the allotted time (p value=0.04). Although 2.5 BPA females exhibited a prolonged latency, the effect did not reach significance (p value=0.06), whereas 2.5 BPA males showed improved latency compared to control males (p value=0.04), although the significance of this result is uncertain. No differences in serum testosterone concentration were detected in any male or female treatment groups. Current findings suggest developmental exposure of rats to BPA may disrupt aspects of spatial navigational learning and memory.

  1. Effects of Developmental Exposure to Bisphenol A on Spatial Navigational Learning and Memory in Rats: A CLARITY-BPA Study

    PubMed Central

    Johnson, Sarah A.; Javurek, Angela B.; Painter, Michele S.; Ellersieck, Mark R.; Welsh, Thomas H.; Camacho, Luísa; Lewis, Sherry M.; Vanlandingham, Michelle M.; Ferguson, Sherry A.; Rosenfeld, Cheryl S.

    2015-01-01

    Bisphenol A (BPA) is a ubiquitous industrial chemical used in the production of a wide variety of items. Previous studies suggest BPA exposure may result in neuro-disruptive effects; however, data are inconsistent across animal and human studies. As part of the Consortium Linking Academic and Regulatory Insights on BPA Toxicity (CLARITY-BPA), we sought to determine whether female and male rats developmentally exposed to BPA demonstrated later spatial navigational learning and memory deficits. Pregnant NCTR Sprague-Dawley rats were orally dosed from gestational day 6 to parturition, and offspring were directly orally dosed until weaning (postnatal day 21). Treatment groups included a vehicle control, three BPA doses (2.5 μg/kg/day-[2.5], 25 μg/kg/day-[25], and 2500 μg/kg/day-[2500]) and a 0.5 μg/kg/day ethinyl estradiol (EE)-reference estrogen dose. At adulthood, 1/sex/litter was tested for seven days in the Barnes maze. The 2500 BPA group sniffed more incorrect holes on day 7 than those in the control, 2.5 BPA, and EE groups. The 2500 BPA females were less likely than control females to locate the escape box in the allotted time (P value= 0.04). Although 2.5 BPA females exhibited a prolonged latency, the effect did not reach significance (P value = 0.06), whereas 2.5 BPA males showed improved latency compared to control males (P value = 0.04), although the significance of this result is uncertain. No differences in serum testosterone concentration were detected in any male or female treatment groups. Current findings suggest developmental exposure of rats to BPA may disrupt aspects of spatial navigational learning and memory. PMID:26436835

  2. Human sex differences in solving a virtual navigation problem.

    PubMed

    Astur, Robert S; Purton, Andrea J; Zaniewski, Melanie J; Cimadevilla, Jose; Markus, Etan J

    2016-07-15

    The current study examined sex differences in initial and subsequent strategies in solving a navigational problem within a virtual reality environment. We tested 163 undergraduates on a virtual T-maze task that included probe trials designed to assess whether participants were responding using either a place or response strategy. Participants were also tested on a mental rotation task and memory of the details of the virtual room. There were no differences between the sexes in copying or recalling a map of the room or on first trial performance of the T-maze. However, at trial two, males show a significant advantage in solving the task, and approximately 80% of the males adopt a place strategy to solve the T-maze whereas females at that point showed no strategy preference. Across all testing, both males and females preferentially used a place strategy. We discuss how factors such as spatial priming affect strategy preferences and how such factors may differentially affect males and females. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Recollection-dependent memory for event duration in large-scale spatial navigation.

    PubMed

    Brunec, Iva K; Ozubko, Jason D; Barense, Morgan D; Moscovitch, Morris

    2017-03-01

    Time and space represent two key aspects of episodic memories, forming the spatiotemporal context of events in a sequence. Little is known, however, about how temporal information, such as the duration and the order of particular events, are encoded into memory, and if it matters whether the memory representation is based on recollection or familiarity. To investigate this issue, we used a real world virtual reality navigation paradigm where periods of navigation were interspersed with pauses of different durations. Crucially, participants were able to reliably distinguish the durations of events that were subjectively "reexperienced" (i.e., recollected), but not of those that were familiar. This effect was not found in temporal order (ordinal) judgments. We also show that the active experience of the passage of time (holding down a key while waiting) moderately enhanced duration memory accuracy. Memory for event duration, therefore, appears to rely on the hippocampally supported ability to recollect or reexperience an event enabling the reinstatement of both its duration and its spatial context, to distinguish it from other events in a sequence. In contrast, ordinal memory appears to rely on familiarity and recollection to a similar extent.

  4. In silico Interrogation of Insect Central Complex Suggests Computational Roles for the Ellipsoid Body in Spatial Navigation.

    PubMed

    Fiore, Vincenzo G; Kottler, Benjamin; Gu, Xiaosi; Hirth, Frank

    2017-01-01

    The central complex in the insect brain is a composite of midline neuropils involved in processing sensory cues and mediating behavioral outputs to orchestrate spatial navigation. Despite recent advances, however, the neural mechanisms underlying sensory integration and motor action selections have remained largely elusive. In particular, it is not yet understood how the central complex exploits sensory inputs to realize motor functions associated with spatial navigation. Here we report an in silico interrogation of central complex-mediated spatial navigation with a special emphasis on the ellipsoid body. Based on known connectivity and function, we developed a computational model to test how the local connectome of the central complex can mediate sensorimotor integration to guide different forms of behavioral outputs. Our simulations show integration of multiple sensory sources can be effectively performed in the ellipsoid body. This processed information is used to trigger continuous sequences of action selections resulting in self-motion, obstacle avoidance and the navigation of simulated environments of varying complexity. The motor responses to perceived sensory stimuli can be stored in the neural structure of the central complex to simulate navigation relying on a collective of guidance cues, akin to sensory-driven innate or habitual behaviors. By comparing behaviors under different conditions of accessible sources of input information, we show the simulated insect computes visual inputs and body posture to estimate its position in space. Finally, we tested whether the local connectome of the central complex might also allow the flexibility required to recall an intentional behavioral sequence, among different courses of actions. Our simulations suggest that the central complex can encode combined representations of motor and spatial information to pursue a goal and thus successfully guide orientation behavior. Together, the observed computational features

  5. In silico Interrogation of Insect Central Complex Suggests Computational Roles for the Ellipsoid Body in Spatial Navigation

    PubMed Central

    Fiore, Vincenzo G.; Kottler, Benjamin; Gu, Xiaosi; Hirth, Frank

    2017-01-01

    The central complex in the insect brain is a composite of midline neuropils involved in processing sensory cues and mediating behavioral outputs to orchestrate spatial navigation. Despite recent advances, however, the neural mechanisms underlying sensory integration and motor action selections have remained largely elusive. In particular, it is not yet understood how the central complex exploits sensory inputs to realize motor functions associated with spatial navigation. Here we report an in silico interrogation of central complex-mediated spatial navigation with a special emphasis on the ellipsoid body. Based on known connectivity and function, we developed a computational model to test how the local connectome of the central complex can mediate sensorimotor integration to guide different forms of behavioral outputs. Our simulations show integration of multiple sensory sources can be effectively performed in the ellipsoid body. This processed information is used to trigger continuous sequences of action selections resulting in self-motion, obstacle avoidance and the navigation of simulated environments of varying complexity. The motor responses to perceived sensory stimuli can be stored in the neural structure of the central complex to simulate navigation relying on a collective of guidance cues, akin to sensory-driven innate or habitual behaviors. By comparing behaviors under different conditions of accessible sources of input information, we show the simulated insect computes visual inputs and body posture to estimate its position in space. Finally, we tested whether the local connectome of the central complex might also allow the flexibility required to recall an intentional behavioral sequence, among different courses of actions. Our simulations suggest that the central complex can encode combined representations of motor and spatial information to pursue a goal and thus successfully guide orientation behavior. Together, the observed computational features

  6. Principles of goal-directed spatial robot navigation in biomimetic models.

    PubMed

    Milford, Michael; Schulz, Ruth

    2014-11-05

    Mobile robots and animals alike must effectively navigate their environments in order to achieve their goals. For animals goal-directed navigation facilitates finding food, seeking shelter or migration; similarly robots perform goal-directed navigation to find a charging station, get out of the rain or guide a person to a destination. This similarity in tasks extends to the environment as well; increasingly, mobile robots are operating in the same underwater, ground and aerial environments that animals do. Yet despite these similarities, goal-directed navigation research in robotics and biology has proceeded largely in parallel, linked only by a small amount of interdisciplinary research spanning both areas. Most state-of-the-art robotic navigation systems employ a range of sensors, world representations and navigation algorithms that seem far removed from what we know of how animals navigate; their navigation systems are shaped by key principles of navigation in 'real-world' environments including dealing with uncertainty in sensing, landmark observation and world modelling. By contrast, biomimetic animal navigation models produce plausible animal navigation behaviour in a range of laboratory experimental navigation paradigms, typically without addressing many of these robotic navigation principles. In this paper, we attempt to link robotics and biology by reviewing the current state of the art in conventional and biomimetic goal-directed navigation models, focusing on the key principles of goal-oriented robotic navigation and the extent to which these principles have been adapted by biomimetic navigation models and why. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  7. Self-navigated motion correction using moments of spatial projections in radial MRI

    NASA Astrophysics Data System (ADS)

    Welch, Edward B.; Rossman, Phillip J.; Felmlee, Joel P.; Manduca, Armando

    2004-05-01

    Interest in radial MRI, also known as projection reconstruction (PR) MRI, has increased recently for uses such as fast scanning and undersampled acquisitions. Additionally, PR acquisitions have intrinsic advantages over standard two-dimensional Fourier transform (2DFT) imaging with respect to motion of the imaged object. It is well known that alignment of each spatial domain projection's center of mass (calculated using each projection's 0th and 1st moments) to the center of the field of view corrects shifts caused by in-plane translation. Here we report a previously unrealized ability to determine the in-plane rotational motion of an imaged object using the 2nd moments of the translation-corrected spatial domain projections. The correction requires only the PR data itself and a new projection view angle acquisition time order. The proposed view angle time order allows the acquisition to be "self-navigating" with respect to both in-plane translation and rotation. Image reconstruction using the aligned projections and detected acquisition angles can eliminate or significantly reduce image artifacts due to such motion. We describe the theory of the correction technique and demonstrate its effectiveness using a computer-controlled motion phantom executing 2-D in-plane translations and a customized pulse sequence capable of introducing known in-plane rotational errors.

  8. Effects of head-slaved navigation and the use of teleports on spatial orientation in virtual environments.

    PubMed

    Bakker, Niels H; Passenier, Peter O; Werkhoven, Peter J

    2003-01-01

    The type of navigation interface in a virtual environment (VE)--head slaved or indirect--determines whether or not proprioceptive feedback stimuli are present during movement. In addition, teleports can be used, which do not provide continuous movement but, rather, discontinuously displace the viewpoint over large distances. A two-part experiment was performed. The first part investigated whether head-slaved navigation provides an advantage for spatial learning in a VE. The second part investigated the role of anticipation when using teleports. The results showed that head-slaved navigation has an advantage over indirect navigation for the acquisition of spatial knowledge in a VE. Anticipating the destination of the teleport prevented disorientation after the displacement to a great extent but not completely. The time that was needed for anticipation increased if the teleport involved a rotation of the viewing direction. This research shows the potential added value of using a head-slaved navigation interface--for example, when using VE for training purposes--and provides practical guidelines for the use of teleports in VE applications.

  9. Self-correction mechanism for path integration in a modular navigation system on the basis of an egocentric spatial map.

    PubMed

    Mudra, Regina; Douglas, Rodney J

    2003-11-01

    Classical Computer Science approaches to navigation by autonomous robots continue to make good progress. However, we have only a limited understanding of how navigation is implemented in the neural networks of animals, which still perform very much better in navigational tasks than robots. In this paper we explore the implementation of neural network based navigation in a simple robot. We use a modular navigation system that contains separate representations of visual input and the path integration process. These representations are combined to influence the behavior of a robot. Both representations are encoded within recurrent neuronal networks. The outputs of the representations are vectors of polar values that encode the location of the nearest object, or of a specific place in the environment. The robot manoeuvres in relation to these attended locations, in the context of its egocentric spatial map. During ego-motion towards a goal, the network representation of the goal moves in a counter-movement due to applied motor feedback. The robot's position is continuously compared against its visual input, and mismatches between the visually perceived goal position and its spatial representation are corrected.

  10. Influence of acute stress on spatial tasks in humans.

    PubMed

    Richardson, Anthony E; VanderKaay Tomasulo, Melissa M

    2011-07-06

    Few studies have investigated the relationship between stress and spatial performance in humans. In this study, participants were exposed to an acute laboratory stressor (Star Mirror Tracing Task) or a control condition (watching a nature video) and then performed two spatial tasks. In the first task, participants navigated through a virtual reality (VR) environment and then returned to the environment to make directional judgments relating to the learned targets. In the second task, perspective taking, participants made directional judgments to targets after imagined body rotations with respect to a map. Compared to the control condition, participants in the Stress condition showed increases in heart rate and systolic and diastolic blood pressure indicating sympathetic adrenal medulla (SAM) axis activation. Participants in the Stress condition also reported being more anxious, angry, frustrated, and irritated than participants in the Non-Stress condition. Salivary cortisol did not differ between conditions, indicating no significant hypothalamic-pituitary-adrenocortical (HPA) axis involvement. In the VR task, memory encoding was unaffected as directional error was similar in both conditions; however, participants in the Stress condition responded more slowly, which may be due to increases in negative affect, SAM disruption in spatial memory retrieval through catecholamine release, or a combination of both factors. In the perspective taking task, participants were also slower to respond after stress, suggesting interference in the ability to adopt new spatial orientations. Additionally, sex differences were observed in that men had greater accuracy on both spatial tasks, but no significant Sex by Stress condition interactions were demonstrated.

  11. Performance-related increases in hippocampal N-acetylaspartate (NAA) induced by spatial navigation training are restricted to BDNF Val homozygotes.

    PubMed

    Lövdén, Martin; Schaefer, Sabine; Noack, Hannes; Kanowski, Martin; Kaufmann, Jörn; Tempelmann, Claus; Bodammer, Nils Christian; Kühn, Simone; Heinze, Hans-Jochen; Lindenberger, Ulman; Düzel, Emrah; Bäckman, Lars

    2011-06-01

    Recent evidence indicates experience-dependent brain volume changes in humans, but the functional and histological nature of such changes is unknown. Here, we report that adult men performing a cognitively demanding spatial navigation task every other day over 4 months display increases in hippocampal N-acetylaspartate (NAA) as measured with magnetic resonance spectroscopy. Unlike measures of brain volume, changes in NAA are sensitive to metabolic and functional aspects of neural and glia tissue and unlikely to reflect changes in microvasculature. Training-induced changes in NAA were, however, absent in carriers of the Met substitution in the brain-derived neurotrophic factor (BDNF) gene, which is known to reduce activity-dependent secretion of BDNF. Among BDNF Val homozygotes, increases in NAA were strongly related to the degree of practice-related improvement in navigation performance and normalized to pretraining levels 4 months after the last training session. We conclude that changes in demands on spatial navigation can alter hippocampal NAA concentrations, confirming epidemiological studies suggesting that mental experience may have direct effects on neural integrity and cognitive performance. BDNF genotype moderates these plastic changes, in line with the contention that gene-context interactions shape the ontogeny of complex phenotypes.

  12. Enhancing fuzzy robot navigation systems by mimicking human visual perception of natural terrain traversibility

    NASA Technical Reports Server (NTRS)

    Tunstel, E.; Howard, A.; Edwards, D.; Carlson, A.

    2001-01-01

    This paper presents a technique for learning to assess terrain traversability for outdoor mobile robot navigation using human-embedded logic and real-time perception of terrain features extracted from image data.

  13. Enhancing fuzzy robot navigation systems by mimicking human visual perception of natural terrain traversibility

    NASA Technical Reports Server (NTRS)

    Tunstel, E.; Howard, A.; Edwards, D.; Carlson, A.

    2001-01-01

    This paper presents a technique for learning to assess terrain traversability for outdoor mobile robot navigation using human-embedded logic and real-time perception of terrain features extracted from image data.

  14. Mechanisms for Human Spatial Competence

    DTIC Science & Technology

    2007-01-01

    including its size, color , and type (e.g., text versus button), which corresponds roughly to the information available in the visual icon. In practice...about objects, including spatial location, color , and size [51]. Because mental images are effortful to maintain, we posit that the visual icon has...volume in auditory perception, brightness in color perception, or intensity in taste, smell, and touch. Since ACT-R has only rudimentary auditory and

  15. Detecting memory and structure in human navigation patterns using Markov chain models of varying order.

    PubMed

    Singer, Philipp; Helic, Denis; Taraghi, Behnam; Strohmaier, Markus

    2014-01-01

    One of the most frequently used models for understanding human navigation on the Web is the Markov chain model, where Web pages are represented as states and hyperlinks as probabilities of navigating from one page to another. Predominantly, human navigation on the Web has been thought to satisfy the memoryless Markov property stating that the next page a user visits only depends on her current page and not on previously visited ones. This idea has found its way in numerous applications such as Google's PageRank algorithm and others. Recently, new studies suggested that human navigation may better be modeled using higher order Markov chain models, i.e., the next page depends on a longer history of past clicks. Yet, this finding is preliminary and does not account for the higher complexity of higher order Markov chain models which is why the memoryless model is still widely used. In this work we thoroughly present a diverse array of advanced inference methods for determining the appropriate Markov chain order. We highlight strengths and weaknesses of each method and apply them for investigating memory and structure of human navigation on the Web. Our experiments reveal that the complexity of higher order models grows faster than their utility, and thus we confirm that the memoryless model represents a quite practical model for human navigation on a page level. However, when we expand our analysis to a topical level, where we abstract away from specific page transitions to transitions between topics, we find that the memoryless assumption is violated and specific regularities can be observed. We report results from experiments with two types of navigational datasets (goal-oriented vs. free form) and observe interesting structural differences that make a strong argument for more contextual studies of human navigation in future work.

  16. Detecting Memory and Structure in Human Navigation Patterns Using Markov Chain Models of Varying Order

    PubMed Central

    Singer, Philipp; Helic, Denis; Taraghi, Behnam; Strohmaier, Markus

    2014-01-01

    One of the most frequently used models for understanding human navigation on the Web is the Markov chain model, where Web pages are represented as states and hyperlinks as probabilities of navigating from one page to another. Predominantly, human navigation on the Web has been thought to satisfy the memoryless Markov property stating that the next page a user visits only depends on her current page and not on previously visited ones. This idea has found its way in numerous applications such as Google's PageRank algorithm and others. Recently, new studies suggested that human navigation may better be modeled using higher order Markov chain models, i.e., the next page depends on a longer history of past clicks. Yet, this finding is preliminary and does not account for the higher complexity of higher order Markov chain models which is why the memoryless model is still widely used. In this work we thoroughly present a diverse array of advanced inference methods for determining the appropriate Markov chain order. We highlight strengths and weaknesses of each method and apply them for investigating memory and structure of human navigation on the Web. Our experiments reveal that the complexity of higher order models grows faster than their utility, and thus we confirm that the memoryless model represents a quite practical model for human navigation on a page level. However, when we expand our analysis to a topical level, where we abstract away from specific page transitions to transitions between topics, we find that the memoryless assumption is violated and specific regularities can be observed. We report results from experiments with two types of navigational datasets (goal-oriented vs. free form) and observe interesting structural differences that make a strong argument for more contextual studies of human navigation in future work. PMID:25013937

  17. Dynamic visual information plays a critical role for spatial navigation in water but not on solid ground.

    PubMed

    Sautter, Chiara Sajidha; Cocchi, Luca; Schenk, Françoise

    2008-12-12

    In the Morris water maze (MWM) task, proprioceptive information is likely to have a poor accuracy due to movement inertia. Hence, in this condition, dynamic visual information providing information on linear and angular acceleration would play a critical role in spatial navigation. To investigate this assumption we compared rat's spatial performance in the MWM and in the homing hole board (HB) tasks using a 1.5 Hz stroboscopic illumination. In the MWM, rats trained in the stroboscopic condition needed more time than those trained in a continuous light condition to reach the hidden platform. They expressed also little accuracy during the probe trial. In the HB task, in contrast, place learning remained unaffected by the stroboscopic light condition. The deficit in the MWM was thus complete, affecting both escape latency and discrimination of the reinforced area, and was thus task specific. This dissociation confirms that dynamic visual information is crucial to spatial navigation in the MWM whereas spatial navigation on solid ground is mediated by a multisensory integration, and thus less dependent on visual information.

  18. The anterior thalamus provides a subcortical circuit supporting memory and spatial navigation.

    PubMed

    Jankowski, Maciej M; Ronnqvist, Kim C; Tsanov, Marian; Vann, Seralynne D; Wright, Nicholas F; Erichsen, Jonathan T; Aggleton, John P; O'Mara, Shane M

    2013-08-30

    The anterior thalamic nuclei (ATN), a central component of Papez' circuit, are generally assumed to be key constituents of the neural circuits responsible for certain categories of learning and memory. Supporting evidence for this contention is that damage to either of two brain regions, the medial temporal lobe and the medial diencephalon, is most consistently associated with anterograde amnesia. Within these respective regions, the hippocampal formation and the ATN (anteromedial, anteroventral, and anterodorsal) are the particular structures of interest. The extensive direct and indirect hippocampal-anterior thalamic interconnections and the presence of theta-modulated cells in both sites further support the hypothesis that these structures constitute a neuronal network crucial for memory and cognition. The major tool in understanding how the brain processes information is the analysis of neuronal output at each hierarchical level along the pathway of signal propagation coupled with neuroanatomical studies. Here, we discuss the electrophysiological properties of cells in the ATN with an emphasis on their role in spatial navigation. In addition, we describe neuroanatomical and functional relationships between the ATN and hippocampal formation.

  19. Sex differences in virtual navigation influenced by scale and navigation experience.

    PubMed

    Padilla, Lace M; Creem-Regehr, Sarah H; Stefanucci, Jeanine K; Cashdan, Elizabeth A

    2017-04-01

    The Morris water maze is a spatial abilities test adapted from the animal spatial cognition literature and has been studied in the context of sex differences in humans. This is because its standard design, which manipulates proximal (close) and distal (far) cues, applies to human navigation. However, virtual Morris water mazes test navigation skills on a scale that is vastly smaller than natural human navigation. Many researchers have argued that navigating in large and small scales is fundamentally different, and small-scale navigation might not simulate natural human navigation. Other work has suggested that navigation experience could influence spatial skills. To address the question of how individual differences influence navigational abilities in differently scaled environments, we employed both a large- (146.4 m in diameter) and a traditional- (36.6 m in diameter) scaled virtual Morris water maze along with a novel measure of navigation experience (lifetime mobility). We found sex differences on the small maze in the distal cue condition only, but in both cue-conditions on the large maze. Also, individual differences in navigation experience modulated navigation performance on the virtual water maze, showing that higher mobility was related to better performance with proximal cues for only females on the small maze, but for both males and females on the large maze.

  20. Hänsel, Gretel and the slime mould—how an external spatial memory aids navigation in complex environments

    NASA Astrophysics Data System (ADS)

    Smith-Ferguson, Jules; Reid, Chris R.; Latty, Tanya; Beekman, Madeleine

    2017-10-01

    The ability to navigate through an environment is critical to most organisms’ ability to survive and reproduce. The presence of a memory system greatly enhances navigational success. Therefore, natural selection is likely to drive the creation of memory systems, even in non-neuronal organisms, if having such a system is adaptive. Here we examine if the external spatial memory system present in the acellular slime mould, Physarum polycephalum, provides an adaptive advantage for resource acquisition. P. polycephalum lays tracks of extracellular slime as it moves through its environment. Previous work has shown that the presence of extracellular slime allows the organism to escape from a trap in laboratory experiments simply by avoiding areas previously explored. Here we further investigate the benefits of using extracellular slime as an external spatial memory by testing the organism’s ability to navigate through environments of differing complexity with and without the ability to use its external memory. Our results suggest that the external memory has an adaptive advantage in ‘open’ and simple bounded environments. However, in a complex bounded environment, the extracellular slime provides no advantage, and may even negatively affect the organism’s navigational abilities. Our results indicate that the exact experimental set up matters if one wants to fully understand how the presence of extracellular slime affects the slime mould’s search behaviour.

  1. Sleep to find your way: the role of sleep in the consolidation of memory for navigation in humans.

    PubMed

    Ferrara, Michele; Iaria, Giuseppe; Tempesta, Daniela; Curcio, Giuseppe; Moroni, Fabio; Marzano, Cristina; De Gennaro, Luigi; Pacitti, Claudio

    2008-01-01

    Although a large body of evidence indicates that sleep plays an important role in learning and memory processes, the actual existence of a sleep-dependent spatial memory consolidation has been not firmly established. Here, by using a computerized 3D virtual navigation tool, we were able to show that topographical orientation in humans largely benefits from sleep after learning, while 10 h of wakefulness during the daytime do not exert similar beneficial effects. In particular, navigation performance enhancement needs sleep in the first post-training night, and no further improvements were seen after a second night of sleep. On the other hand, sleep deprivation hinders any performance enhancement and exerts a proactive disruption of spatial memory consolidation, since recovery sleep do not revert its effects. Spatial memory performance does not benefit from the simple passage of time, and a period of wakefulness between learning and sleep does not seem to have the role of stabilizing memory traces. In conclusion, our results indicate that spatial performance improvement is observed only when learning is followed by a period of sleep, regardless of the retention interval length. (c) 2008 Wiley-Liss, Inc.

  2. A multimodal image guiding system for Navigated Ultrasound Bronchoscopy (EBUS): A human feasibility study

    PubMed Central

    Hofstad, Erlend Fagertun; Amundsen, Tore; Langø, Thomas; Bakeng, Janne Beate Lervik; Leira, Håkon Olav

    2017-01-01

    Background Endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) is the endoscopic method of choice for confirming lung cancer metastasis to mediastinal lymph nodes. Precision is crucial for correct staging and clinical decision-making. Navigation and multimodal imaging can potentially improve EBUS-TBNA efficiency. Aims To demonstrate the feasibility of a multimodal image guiding system using electromagnetic navigation for ultrasound bronchoschopy in humans. Methods Four patients referred for lung cancer diagnosis and staging with EBUS-TBNA were enrolled in the study. Target lymph nodes were predefined from the preoperative computed tomography (CT) images. A prototype convex probe ultrasound bronchoscope with an attached sensor for position tracking was used for EBUS-TBNA. Electromagnetic tracking of the ultrasound bronchoscope and ultrasound images allowed fusion of preoperative CT and intraoperative ultrasound in the navigation software. Navigated EBUS-TBNA was used to guide target lymph node localization and sampling. Navigation system accuracy was calculated, measured by the deviation between lymph node position in ultrasound and CT in three planes. Procedure time, diagnostic yield and adverse events were recorded. Results Preoperative CT and real-time ultrasound images were successfully fused and displayed in the navigation software during the procedures. Overall navigation accuracy (11 measurements) was 10.0 ± 3.8 mm, maximum 17.6 mm, minimum 4.5 mm. An adequate sample was obtained in 6/6 (100%) of targeted lymph nodes. No adverse events were registered. Conclusions Electromagnetic navigated EBUS-TBNA was feasible, safe and easy in this human pilot study. The clinical usefulness was clearly demonstrated. Fusion of real-time ultrasound, preoperative CT and electromagnetic navigational bronchoscopy provided a controlled guiding to level of target, intraoperative overview and procedure documentation. PMID:28182758

  3. Driver-passenger collaboration as a basis for human-machine interface design for vehicle navigation systems.

    PubMed

    Antrobus, Vicki; Burnett, Gary; Krehl, Claudia

    2017-03-01

    Human Factors concerns exist with vehicle navigation systems, particularly relating to the effects of current Human-Machine Interfaces (HMIs) on driver disengagement from the environment. A road study was conducted aiming to provide initial input for the development of intelligent HMIs for in-vehicle systems, using the traditional collaborative navigation relationship between the driver and passenger to inform future design. Sixteen drivers navigated a predefined route in the city of Coventry, UK with the assistance of an existing vehicle navigation system (SatNav), whereas a further 16 followed the navigational prompts of a passenger who had been trained along the same route. Results found that there were no significant differences in the number of navigational errors made on route for the two different methods. However, drivers utilising a collaborative navigation approach had significantly better landmark and route knowledge than their SatNav counterparts. Analysis of individual collaborative transcripts revealed the large individual differences in descriptor use by passengers and reference to environmental landmarks, illustrating the potential for the replacement of distance descriptors in vehicle navigation systems. Results are discussed in the context of future HMIs modelled on a collaborative navigation relationship. Practitioner Summary: Current navigation systems have been associated with driver environmental disengagement, this study uses an on-road approach to look at how the driver-passenger collaborative relationship and dialogue can inform future navigation HMI design. Drivers navigating with passenger assistance demonstrated enhanced landmark and route knowledge over drivers navigating with a SatNav.

  4. Optimal estimator model for human spatial orientation

    NASA Technical Reports Server (NTRS)

    Borah, J.; Young, L. R.; Curry, R. E.

    1979-01-01

    A model is being developed to predict pilot dynamic spatial orientation in response to multisensory stimuli. Motion stimuli are first processed by dynamic models of the visual, vestibular, tactile, and proprioceptive sensors. Central nervous system function is then modeled as a steady-state Kalman filter which blends information from the various sensors to form an estimate of spatial orientation. Where necessary, this linear central estimator has been augmented with nonlinear elements to reflect more accurately some highly nonlinear human response characteristics. Computer implementation of the model has shown agreement with several important qualitative characteristics of human spatial orientation, and it is felt that with further modification and additional experimental data the model can be improved and extended. Possible means are described for extending the model to better represent the active pilot with varying skill and work load levels.

  5. Optimal estimator model for human spatial orientation

    NASA Technical Reports Server (NTRS)

    Borah, J.; Young, L. R.; Curry, R. E.

    1979-01-01

    A model is being developed to predict pilot dynamic spatial orientation in response to multisensory stimuli. Motion stimuli are first processed by dynamic models of the visual, vestibular, tactile, and proprioceptive sensors. Central nervous system function is then modeled as a steady-state Kalman filter which blends information from the various sensors to form an estimate of spatial orientation. Where necessary, this linear central estimator has been augmented with nonlinear elements to reflect more accurately some highly nonlinear human response characteristics. Computer implementation of the model has shown agreement with several important qualitative characteristics of human spatial orientation, and it is felt that with further modification and additional experimental data the model can be improved and extended. Possible means are described for extending the model to better represent the active pilot with varying skill and work load levels.

  6. Geometric Determinants of Human Spatial Memory

    ERIC Educational Resources Information Center

    Hartley, Tom; Trinkler, Iris; Burgess, Neil

    2004-01-01

    Geometric alterations to the boundaries of a virtual environment were used to investigate the representations underlying human spatial memory. Subjects encountered a cue object in a simple rectangular enclosure, with distant landmarks for orientation. After a brief delay, during which they were removed from the arena, subjects were returned to it…

  7. Low-frequency theta oscillations in the human hippocampus during real-world and virtual navigation

    PubMed Central

    Bohbot, Véronique D.; Copara, Milagros S.; Gotman, Jean; Ekstrom, Arne D.

    2017-01-01

    Low-Frequency Oscillations (LFO) in the range of 7–9 Hz, or theta rhythm, has been recorded in rodents ambulating in the real world. However, intra-hippocampus EEG recordings during virtual navigation in humans have consistently reported LFO that appear to predominate around 3–4 Hz. Here we report clear evidence of 7–9 Hz rhythmicity in raw intra-hippocampus EEG traces during real as well as virtual movement. Oscillations typically occur at a lower frequency in virtual than real world navigation. This study highlights the possibility that human and rodent hippocampal EEG activity are not as different as previously reported and this difference may arise, in part, due to the lack of actual movement in previous human navigation studies, which were virtual. PMID:28195129

  8. Low-frequency theta oscillations in the human hippocampus during real-world and virtual navigation.

    PubMed

    Bohbot, Véronique D; Copara, Milagros S; Gotman, Jean; Ekstrom, Arne D

    2017-02-14

    Low-Frequency Oscillations (LFO) in the range of 7-9 Hz, or theta rhythm, has been recorded in rodents ambulating in the real world. However, intra-hippocampus EEG recordings during virtual navigation in humans have consistently reported LFO that appear to predominate around 3-4 Hz. Here we report clear evidence of 7-9 Hz rhythmicity in raw intra-hippocampus EEG traces during real as well as virtual movement. Oscillations typically occur at a lower frequency in virtual than real world navigation. This study highlights the possibility that human and rodent hippocampal EEG activity are not as different as previously reported and this difference may arise, in part, due to the lack of actual movement in previous human navigation studies, which were virtual.

  9. Dorso-medial and ventro-lateral functional specialization of the human retrosplenial complex in spatial updating and orienting.

    PubMed

    Burles, Ford; Slone, Edward; Iaria, Giuseppe

    2017-04-01

    The retrosplenial complex is a region within the posterior cingulate cortex implicated in spatial navigation. Here, we investigated the functional specialization of this large and anatomically heterogeneous region using fMRI and resting-state functional connectivity combined with a spatial task with distinct phases of spatial 'updating' (i.e., integrating and maintaining object locations in memory during spatial displacement) and 'orienting' (i.e., recalling unseen locations from current position in space). Both spatial 'updating' and 'orienting' produced bilateral activity in the retrosplenial complex, among other areas. However, spatial 'updating' produced slightly greater activity in ventro-lateral portions, of the retrosplenial complex, whereas spatial 'orienting' produced greater activity in a more dorsal and medial portion of it (both regions localized along the parieto-occipital fissure). At rest, both ventro-lateral and dorso-medial subregions of the retrosplenial complex were functionally connected to the hippocampus and parahippocampus, regions both involved in spatial orientation and navigation. However, the ventro-lateral subregion of the retrosplenial complex displayed more positive functional connectivity with ventral occipital and temporal object recognition regions, whereas the dorso-medial subregion activity was more correlated to dorsal activity and frontal activity, as well as negatively correlated with more ventral parietal structures. These findings provide evidence for a dorso-medial to ventro-lateral functional specialization within the human retrosplenial complex that may shed more light on the complex neural mechanisms underlying spatial orientation and navigation in humans.

  10. Spatial cognition in apes and humans.

    PubMed

    Gentner, Dedre

    2007-05-01

    The debate on whether language influences cognition is sometimes seen as a simple dichotomy: cognitive development is governed either by innate predispositions or by influences of language and culture. In two recent papers on spatial cognition, Haun and colleagues break new ground in bringing together a comparative cognition approach with a cross-linguistic framework to arrive at a third position: that humans begin with the same spatial reference frames as our near relatives, the great apes, and diverge later owing to the influence of language and culture.

  11. Using virtual reality to investigate comparative spatial cognitive abilities in chimpanzees and humans.

    PubMed

    Dolins, Francine L; Klimowicz, Christopher; Kelley, John; Menzel, Charles R

    2014-05-01

    The purpose of the present study was to determine the efficacy of investigating spatial cognitive abilities across two primate species using virtual reality. In this study, we presented four captive adult chimpanzees and 16 humans (12 children and 4 adults) with simulated environments of increasing complexity and size to compare species' attention to visuo-spatial features during navigation. The specific task required participants to attend to landmarks in navigating along routes in order to localize the goal site. Both species were found to discriminate effectively between positive and negative landmarks. Assessing path efficiency revealed that both species and all age groups used relatively efficient, distance reducing routes during navigation. Compared to the chimpanzees and adult humans however, younger children's performance decreased as maze complexity and size increased. Surprisingly, in the most complex maze category the humans' performance was less accurate compared to one female chimpanzee. These results suggest that the method of using virtual reality to test captive primates, and in particular, chimpanzees, affords significant cross-species investigations of spatial cognitive and developmental comparisons. © 2014 Wiley Periodicals, Inc.

  12. Modulation of spatial and response strategies by phase of the menstrual cycle in women tested in a virtual navigation task.

    PubMed

    Hussain, Dema; Hanafi, Sarah; Konishi, Kyoko; Brake, Wayne G; Bohbot, Véronique D

    2016-08-01

    Different memory systems are employed to navigate an environment. It has been consistently shown in rodents that estrogen impacts multiple memory system bias such that low estradiol (E2) is associated with increased use of a striatal-mediated response strategy whereas high E2 increases use of a hippocampal-dependent spatial memory. Low E2 also enhances performance on a response-based task whereas high E2 levels improve learning on a spatial task. The purpose of the present cross-sectional study was to investigate navigational strategies in young, healthy, naturally cycling women. Participants were split into either an early follicular (i.e., when E2 levels are low), ovulatory (i.e., when E2 levels are high) or mid/late luteal (i.e., end of the cycle, when E2 levels decrease and progesterone levels rise) phase group, using self-reported date of the menstrual cycle. Serum hormone level measurements (E2, progesterone, testosterone) were used to confirm cycle phase assignment. Participants were administered a verbal memory task as well as a virtual navigation task that can be solved by using either a response or spatial strategy. Women tested in the ovulatory phase, under high E2 conditions, performed better on a verbal memory task than women tested during the other phases of the cycle. Interestingly, women tested in the mid/late luteal phase, when progesterone is high, predominantly used a spatial strategy, whereas the opposite pattern was observed in the early follicular and ovulatory groups. Our data suggest that the specific memory system engaged differs depending on the phase of the menstrual cycle and may be mediated by both E2 and progesterone, rather than E2 alone. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. The quantitative modelling of human spatial habitability

    NASA Technical Reports Server (NTRS)

    Wise, J. A.

    1985-01-01

    A model for the quantitative assessment of human spatial habitability is presented in the space station context. The visual aspect assesses how interior spaces appear to the inhabitants. This aspect concerns criteria such as sensed spaciousness and the affective (emotional) connotations of settings' appearances. The kinesthetic aspect evaluates the available space in terms of its suitability to accommodate human movement patterns, as well as the postural and anthrometric changes due to microgravity. Finally, social logic concerns how the volume and geometry of available space either affirms or contravenes established social and organizational expectations for spatial arrangements. Here, the criteria include privacy, status, social power, and proxemics (the uses of space as a medium of social communication).

  14. Human Plague Risk: Spatial-Temporal Models

    NASA Technical Reports Server (NTRS)

    Pinzon, Jorge E.

    2010-01-01

    This chpater reviews the use of spatial-temporal models in identifying potential risks of plague outbreaks into the human population. Using earth observations by satellites remote sensing there has been a systematic analysis and mapping of the close coupling between the vectors of the disease and climate variability. The overall result is that incidence of plague is correlated to positive El Nino/Southem Oscillation (ENSO).

  15. Navigational Planning in Orienteering

    NASA Astrophysics Data System (ADS)

    Murakoshi, Shin

    Navigation is a human activity with the aim being to arrive at a predetermined destination. In order to find the way to the destination, the use of current input from the actual environment while travelling is needed as well as stored and organized knowledge of the local geography. Although the knowledge requirement has been studied extensively in the form of cognitive maps or other spatial representation, few studies deal with how the knowledge is used together with the input from the actual environment while navigating.

  16. Ecological validity of virtual environments to assess human navigation ability

    PubMed Central

    van der Ham, Ineke J. M.; Faber, Annemarie M. E.; Venselaar, Matthijs; van Kreveld, Marc J.; Löffler, Maarten

    2015-01-01

    Route memory is frequently assessed in virtual environments. These environments can be presented in a fully controlled manner and are easy to use. Yet they lack the physical involvement that participants have when navigating real environments. For some aspects of route memory this may result in reduced performance in virtual environments. We assessed route memory performance in four different environments: real, virtual, virtual with directional information (compass), and hybrid. In the hybrid environment, participants walked the route outside on an open field, while all route information (i.e., path, landmarks) was shown simultaneously on a handheld tablet computer. Results indicate that performance in the real life environment was better than in the virtual conditions for tasks relying on survey knowledge, like pointing to start and end point, and map drawing. Performance in the hybrid condition however, hardly differed from real life performance. Performance in the virtual environment did not benefit from directional information. Given these findings, the hybrid condition may offer the best of both worlds: the performance level is comparable to that of real life for route memory, yet it offers full control of visual input during route learning. PMID:26074831

  17. Complementary Roles of the Hippocampus and the Dorsomedial Striatum during Spatial and Sequence-Based Navigation Behavior

    PubMed Central

    Watilliaux, Aurélie; Bontempi, Bruno; Rondi-Reig, Laure

    2013-01-01

    We investigated the neural bases of navigation based on spatial or sequential egocentric representation during the completion of the starmaze, a complex goal-directed navigation task. In this maze, mice had to swim along a path composed of three choice points to find a hidden platform. As reported previously, this task can be solved by using two hippocampal-dependent strategies encoded in parallel i) the allocentric strategy requiring encoding of the contextual information, and ii) the sequential egocentric strategy requiring temporal encoding of a sequence of successive body movements associated to specific choice points. Mice were trained during one day and tested the following day in a single probe trial to reveal which of the two strategies was spontaneously preferred by each animal. Imaging of the activity-dependent gene c-fos revealed that both strategies are supported by an overlapping network involving the dorsal hippocampus, the dorsomedial striatum (DMS) and the medial prefrontal cortex. A significant higher activation of the ventral CA1 subregion was observed when mice used the sequential egocentric strategy. To investigate the potential different roles of the dorsal hippocampus and the DMS in both types of navigation, we performed region-specific excitotoxic lesions of each of these two structures. Dorsal hippocampus lesioned mice were unable to optimally learn the sequence but improved their performances by developing a serial strategy instead. DMS lesioned mice were severely impaired, failing to learn the task. Our data support the view that the hippocampus organizes information into a spatio-temporal representation, which can then be used by the DMS to perform goal-directed navigation. PMID:23826243

  18. The quantitative modelling of human spatial habitability

    NASA Technical Reports Server (NTRS)

    Wise, James A.

    1988-01-01

    A theoretical model for evaluating human spatial habitability (HuSH) in the proposed U.S. Space Station is developed. Optimizing the fitness of the space station environment for human occupancy will help reduce environmental stress due to long-term isolation and confinement in its small habitable volume. The development of tools that operationalize the behavioral bases of spatial volume for visual kinesthetic, and social logic considerations is suggested. This report further calls for systematic scientific investigations of how much real and how much perceived volume people need in order to function normally and with minimal stress in space-based settings. The theoretical model presented in this report can be applied to any size or shape interior, at any scale of consideration, for the Space Station as a whole to an individual enclosure or work station. Using as a point of departure the Isovist model developed by Dr. Michael Benedikt of the U. of Texas, the report suggests that spatial habitability can become as amenable to careful assessment as engineering and life support concerns.

  19. Developmental Changes in Structural and Functional Properties of Hippocampal AMPARs Parallels the Emergence of Deliberative Spatial Navigation in Juvenile Rats

    PubMed Central

    Blair, Margaret G.; Nguyen, Nhu N.-Q.; Albani, Sarah H.; L'Etoile, Matthew M.; Andrawis, Marina M.; Owen, Leanna M.; Oliveira, Rodrigo F.; Johnson, Matthew W.; Purvis, Dianna L.; Sanders, Erin M.; Stoneham, Emily T.; Xu, Huaying

    2013-01-01

    The neural mechanisms that support the late postnatal development of spatial navigation are currently unknown. We investigated this in rats and found that an increase in the duration of AMPAR-mediated synaptic responses in the hippocampus was related to the emergence of spatial navigation. More specifically, spontaneous alternation rate, a behavioral indicator of hippocampal integrity, increased at the end of the third postnatal week in association with increases in AMPAR response duration at SC-CA1 synapses and synaptically driven postsynaptic discharge of CA1 pyramidal neurons. Pharmacological prolongation of glutamatergic synaptic transmission in juveniles increased the spontaneous alternation rate and CA1 postsynaptic discharge and reduced the threshold for the induction of activity-dependent synaptic plasticity at SC-CA1 synapses. A decrease in GluA1 and increases in GluA3 subunit and transmembrane AMPAR regulatory protein (TARP) expression at the end of the third postnatal week provide a molecular explanation for the increase in AMPAR response duration and reduced efficacy of AMPAR modulators with increasing age. A shift in the composition of AMPARs and increased association with AMPAR protein complex accessory proteins at the end of the third postnatal week likely “turns on” the hippocampus by increasing AMPAR response duration and postsynaptic excitability and reducing the threshold for activity-dependent synaptic potentiation. PMID:23884930

  20. Downregulation of brain mineralocorticoid and glucocorticoid receptor by antisense oligodeoxynucleotide treatment fails to alter spatial navigation in rats.

    PubMed

    Engelmann, M; Landgraf, R; Lörscher, P; Conzelmann, C; Probst, J C; Holsboer, F; Reul, J M

    1998-11-13

    Adult male Brown Norway rats were long-term intracerebroventricularly (i.c.v.) infused with antisense oligodeoxynucleotides (18-mer, double endcapped phosphorothioate protected) targeting either mineralocorticoid or glucocorticoid receptor mRNA, or received the respective mixed bases sequence or vehicle. Mineralocorticoid receptor-mixed bases and glucocorticoid receptor-mixed bases oligodeoxynucleotide infusion (1 microg/0.5 microl/h) over a time period of seven days did not alter hippocampal mineralocorticoid receptor and glucocorticoid receptor binding when compared to vehicle treatment. In contrast, i.c.v. administration of mineralocorticoid receptor, as well as glucocorticoid receptor-antisense over the same time period resulted in a significantly reduced binding of mineralocorticoid receptor and glucocorticoid receptor in the hippocampus [mineralocorticoid receptor-antisense group approx. 72% of mineralocorticoid receptor-mixed bases and vehicle groups (100%); glucocorticoid receptor antisense group approx. 77% of glucocorticoid receptor-mixed bases and vehicle]. The specificity of these antisense effects is indicated by the finding that rats treated with mineralocorticoid receptor-antisense did not show any changes in glucocorticoid receptor and vice versa. Animals treated according to this infusion protocol and tested in the Morris water maze for their spatial navigation abilities failed to show significant differences among the groups. These data indicate that a reduction of hippocampal mineralocorticoid receptor or glucocorticoid receptor binding capacity by 20-30% does not interfere with spatial navigation.

  1. Posterior neocortical (visual cortex) lesions in the rat impair matching-to-place navigation in a swimming pool: a reevaluation of cortical contributions to spatial behavior using a new assessment of spatial versus non-spatial behavior.

    PubMed

    Whishaw, Ian Q

    2004-12-06

    In the face of contradictory findings on the role of visual cortex contributions to spatial behavior, the present study evaluated the ability of rats with primary visual cortex (Area 17) lesions to learn spatial problems in a swimming pool. Because the solution to any spatial learning problem consists of acquiring at least two primary elements of a task, task procedures and spatial learning, the study, in addition to assessing spatial ability on a place task, used two training/testing methods to identify the nature of the spatial impairment associated with visual cortex lesions. Non-spatial training consisted of learning to find a platform in the dark and spatial training consisted of a series of matching-to-place problems. The results confirmed that although rats with visual cortex lesions were impaired on place learning, the deficit was partially ameliorated by non-spatial training given following the lesion, and completely ameliorated by non-spatial training given before the lesion. Nevertheless, all visual cortex groups failed to show a quadrant preference on a probe trial and displayed a profound impairment in matching-to-place learning. This definitive demonstration that appropriate testing methods can reveal a failure in spatial behavior following visual cortex lesions is consistent with the idea that primary visual cortex is required in spatial navigation.

  2. 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.

  3. sLORETA current source density analysis of evoked potentials for spatial updating in a virtual navigation task.

    PubMed

    Nguyen, Hai M; Matsumoto, Jumpei; Tran, Anh H; Ono, Taketoshi; Nishijo, Hisao

    2014-01-01

    Previous studies have reported that multiple brain regions are activated during spatial navigation. However, it is unclear whether these activated brain regions are specifically associated with spatial updating or whether some regions are recruited for parallel cognitive processes. The present study aimed to localize current sources of event related potentials (ERPs) associated with spatial updating specifically. In the control phase of the experiment, electroencephalograms (EEGs) were recorded while subjects sequentially traced 10 blue checkpoints on the streets of a virtual town, which were sequentially connected by a green line, by manipulating a joystick. In the test phase of the experiment, the checkpoints and green line were not indicated. Instead, a tone was presented when the subjects entered the reference points where they were then required to trace the 10 invisible spatial reference points corresponding to the checkpoints. The vertex-positive ERPs with latencies of approximately 340 ms from the moment when the subjects entered the unmarked reference points were significantly larger in the test than in the control phases. Current source density analysis of the ERPs by standardized low-resolution brain electromagnetic tomography (sLORETA) indicated activation of brain regions in the test phase that are associated with place and landmark recognition (entorhinal cortex/hippocampus, parahippocampal and retrosplenial cortices, fusiform, and lingual gyri), detecting self-motion (posterior cingulate and posterior insular cortices), motor planning (superior frontal gyrus, including the medial frontal cortex), and regions that process spatial attention (inferior parietal lobule). The present results provide the first identification of the current sources of ERPs associated with spatial updating, and suggest that multiple systems are active in parallel during spatial updating.

  4. Mining Missing Hyperlinks from Human Navigation Traces: A Case Study of Wikipedia

    PubMed Central

    West, Robert; Paranjape, Ashwin; Leskovec, Jure

    2015-01-01

    Hyperlinks are an essential feature of the World Wide Web. They are especially important for online encyclopedias such as Wikipedia: an article can often only be understood in the context of related articles, and hyperlinks make it easy to explore this context. But important links are often missing, and several methods have been proposed to alleviate this problem by learning a linking model based on the structure of the existing links. Here we propose a novel approach to identifying missing links in Wikipedia. We build on the fact that the ultimate purpose of Wikipedia links is to aid navigation. Rather than merely suggesting new links that are in tune with the structure of existing links, our method finds missing links that would immediately enhance Wikipedia's navigability. We leverage data sets of navigation paths collected through a Wikipedia-based human-computation game in which users must find a short path from a start to a target article by only clicking links encountered along the way. We harness human navigational traces to identify a set of candidates for missing links and then rank these candidates. Experiments show that our procedure identifies missing links of high quality. PMID:26634229

  5. Mining Missing Hyperlinks from Human Navigation Traces: A Case Study of Wikipedia.

    PubMed

    West, Robert; Paranjape, Ashwin; Leskovec, Jure

    Hyperlinks are an essential feature of the World Wide Web. They are especially important for online encyclopedias such as Wikipedia: an article can often only be understood in the context of related articles, and hyperlinks make it easy to explore this context. But important links are often missing, and several methods have been proposed to alleviate this problem by learning a linking model based on the structure of the existing links. Here we propose a novel approach to identifying missing links in Wikipedia. We build on the fact that the ultimate purpose of Wikipedia links is to aid navigation. Rather than merely suggesting new links that are in tune with the structure of existing links, our method finds missing links that would immediately enhance Wikipedia's navigability. We leverage data sets of navigation paths collected through a Wikipedia-based human-computation game in which users must find a short path from a start to a target article by only clicking links encountered along the way. We harness human navigational traces to identify a set of candidates for missing links and then rank these candidates. Experiments show that our procedure identifies missing links of high quality.

  6. Spatial updating in human parietal cortex

    NASA Technical Reports Server (NTRS)

    Merriam, Elisha P.; Genovese, Christopher R.; Colby, Carol L.

    2003-01-01

    Single neurons in monkey parietal cortex update visual information in conjunction with eye movements. This remapping of stimulus representations is thought to contribute to spatial constancy. We hypothesized that a similar process occurs in human parietal cortex and that we could visualize it with functional MRI. We scanned subjects during a task that involved remapping of visual signals across hemifields. We observed an initial response in the hemisphere contralateral to the visual stimulus, followed by a remapped response in the hemisphere ipsilateral to the stimulus. We ruled out the possibility that this remapped response resulted from either eye movements or visual stimuli alone. Our results demonstrate that updating of visual information occurs in human parietal cortex.

  7. Spatial updating in human parietal cortex

    NASA Technical Reports Server (NTRS)

    Merriam, Elisha P.; Genovese, Christopher R.; Colby, Carol L.

    2003-01-01

    Single neurons in monkey parietal cortex update visual information in conjunction with eye movements. This remapping of stimulus representations is thought to contribute to spatial constancy. We hypothesized that a similar process occurs in human parietal cortex and that we could visualize it with functional MRI. We scanned subjects during a task that involved remapping of visual signals across hemifields. We observed an initial response in the hemisphere contralateral to the visual stimulus, followed by a remapped response in the hemisphere ipsilateral to the stimulus. We ruled out the possibility that this remapped response resulted from either eye movements or visual stimuli alone. Our results demonstrate that updating of visual information occurs in human parietal cortex.

  8. Spatial patterning of vulture scavenged human remains.

    PubMed

    Spradley, M Katherine; Hamilton, Michelle D; Giordano, Alberto

    2012-06-10

    This article presents the results of a pilot study on the effects of vulture modification to human remains. A donated body from the Willed Body Donation Program was placed at the Forensic Anthropology Research Facility (FARF), an outdoor human decomposition laboratory located at Texas State University-San Marcos. The effects of vulture scavenging on the timing and sequence, and the rate of skeletonization, disarticulation, and dispersal were observed via a motion sensing camera and direct observation. Using GIS (Geographic Information Systems) and GPS (Global Positioning System) technologies and spatial analytical methods, the transport of skeletal elements was mapped in order to analyze dispersal and terrain-influenced patterns of active vulture scavenging. Results showed that the initial scavenging took place 37 days after placement at FARF. This delay in scavenging differs from previous research. After the initial appearance of the vultures, the body was reduced from a fully-fleshed individual to a skeleton within only 5h. This underscores the potential for errors in postmortem interval estimations made at vulture scavenged scenes. Additionally, spatial analysis showed that skeletal elements were dispersed by vultures to lower elevations, and that the disarticulation and dispersal of the skeletal elements occurs early in the scavenging sequence.

  9. Distinct contributions of human hippocampal theta to spatial cognition and anxiety

    PubMed Central

    Cornwell, Brian R.; Arkin, Nicole; Overstreet, Cassie; Carver, Frederick W.; Grillon, Christian

    2012-01-01

    Summary Current views of the hippocampus assign this structure, and its prominent theta rhythms, a key role in both cognition and affect. We studied this duality of function in humans, where no direct evidence exists. Whole-head magnetoencephalographic (MEG) data were recorded to measure theta activity while healthy participants (N = 25) navigated two virtual Morris water mazes, one in which they risked receiving aversive shocks without warning to induce anxiety and one in which they were safe from shocks. Results showed that threat of shock elevated anxiety level and enhanced navigation performance compared to the safe condition. MEG source analyses revealed that improved navigation performance during threat was preferentially associated with increased left septal (posterior) hippocampal theta (specifically 4–8 Hz activity), replicating previous research that emphasizes a predominant role of the septal third of the hippocampus in spatial cognition. Moreover, increased self-reported anxiety during threat was preferentially associated with increased left temporal (anterior) hippocampal theta (specifically 2–6 Hz activity), consistent with this region’s involvement in mediating conditioned and innate fear. Supporting contemporary theory, these findings highlight simultaneous involvement of the human hippocampus in spatial cognition and anxiety, and clarify their distinct correlates. PMID:22467298

  10. 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

  11. 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.

  12. 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

  13. 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

    Lind, Sophie E; Williams, David M; Raber, Jacob; Peel, Anna; Bowler, Dermot M

    2013-11-01

    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.

  14. A goal-directed spatial navigation model using forward trajectory planning based on grid cells.

    PubMed

    Erdem, Uğur M; Hasselmo, Michael

    2012-03-01

    A goal-directed navigation model is proposed based on forward linear look-ahead probe of trajectories in a network of head direction cells, grid cells, place cells and prefrontal cortex (PFC) cells. The model allows selection of new goal-directed trajectories. In a novel environment, the virtual rat incrementally creates a map composed of place cells and PFC cells by random exploration. After exploration, the rat retrieves memory of the goal location, picks its next movement direction by forward linear look-ahead probe of trajectories in several candidate directions while stationary in one location, and finds the one activating PFC cells with the highest reward signal. Each probe direction involves activation of a static pattern of head direction cells to drive an interference model of grid cells to update their phases in a specific direction. The updating of grid cell spiking drives place cells along the probed look-ahead trajectory similar to the forward replay during waking seen in place cell recordings. Directions are probed until the look-ahead trajectory activates the reward signal and the corresponding direction is used to guide goal-finding behavior. We report simulation results in several mazes with and without barriers. Navigation with barriers requires a PFC map topology based on the temporal vicinity of visited place cells and a reward signal diffusion process. The interaction of the forward linear look-ahead trajectory probes with the reward diffusion allows discovery of never-before experienced shortcuts towards a goal location.

  15. A Goal-Directed Spatial Navigation Model Using Forward Trajectory Planning Based on Grid Cells

    PubMed Central

    Erdem, Uğur Murat; Hasselmo, Michael E.

    2012-01-01

    A goal-directed navigation model is proposed based on forward linear look-ahead probe of trajectories in a network of head direction cells, grid cells, place cells, and prefrontal cortex (PFC) cells. The model allows selection of new goal-directed trajectories. In a novel environment, the virtual rat incrementally creates a map composed of place cells and PFC cells by random exploration. After exploration, the rat retrieves memory of the goal location, picks its next movement direction by forward linear look-ahead probe of trajectories in several candidate directions while stationary in one location, and finds the one activating PFC cells with the highest reward signal. Each probe direction involves activation of a static pattern of head direction cells to drive an interference model of grid cells to update their phases in a specific direction. The updating of grid cell spiking drives place cells along the probed look-ahead trajectory similar to the forward replay during waking seen in place cell recordings. Directions are probed until the look-ahead trajectory activates the reward signal and the corresponding direction is used to guide goal-finding behavior. We report simulation results in several mazes with and without barriers. Navigation with barriers requires a PFC map topology based on the temporal vicinity of visited place cells and a reward signal diffusion process. The interaction of the forward linear look-ahead trajectory probes with the reward diffusion allows discovery of never before experienced shortcuts towards a goal location. PMID:22393918

  16. A Map for Social Navigation in the Human Brain

    PubMed Central

    Tavares, Rita Morais; Mendelsohn, Avi; Grossman, Yael; Williams, Christian Hamilton; Shapiro, Matthew; Trope, Yaacov; Schiller, Daniela

    2015-01-01

    SUMMARY Deciphering the neural mechanisms of social behavior has propelled the growth of social neuroscience. The exact computations of the social brain, however, remain elusive. Here we investigated how the human brain tracks ongoing changes in social relationships using functional neuroimaging. Participants were lead characters in a role-playing game in which they were to find a new home and a job through interactions with virtual cartoon characters. We found that a two-dimensional geometric model of social relationships, a “social space” framed by power and affiliation, predicted hippocampal activity. Moreover, participants who reported better social skills showed stronger covariance between hippocampal activity and “movement” through “social space.” The results suggest that the hippocampus is crucial for social cognition, and imply that beyond framing physical locations, the hippocampus computes a more general, inclusive, abstract, and multidimensional cognitive map consistent with its role in episodic memory. PMID:26139376

  17. Spatial cyberinfrastructures, ontologies, and the humanities

    PubMed Central

    Sieber, Renee E.; Wellen, Christopher C.; Jin, Yuan

    2011-01-01

    We report on research into building a cyberinfrastructure for Chinese biographical and geographic data. Our cyberinfrastructure contains (i) the McGill-Harvard-Yenching Library Ming Qing Women's Writings database (MQWW), the only online database on historical Chinese women's writings, (ii) the China Biographical Database, the authority for Chinese historical people, and (iii) the China Historical Geographical Information System, one of the first historical geographic information systems. Key to this integration is that linked databases retain separate identities as bases of knowledge, while they possess sufficient semantic interoperability to allow for multidatabase concepts and to support cross-database queries on an ad hoc basis. Computational ontologies create underlying semantics for database access. This paper focuses on the spatial component in a humanities cyberinfrastructure, which includes issues of conflicting data, heterogeneous data models, disambiguation, and geographic scale. First, we describe the methodology for integrating the databases. Then we detail the system architecture, which includes a tier of ontologies and schema. We describe the user interface and applications that allow for cross-database queries. For instance, users should be able to analyze the data, examine hypotheses on spatial and temporal relationships, and generate historical maps with datasets from MQWW for research, teaching, and publication on Chinese women writers, their familial relations, publishing venues, and the literary and social communities. Last, we discuss the social side of cyberinfrastructure development, as people are considered to be as critical as the technical components for its success. PMID:21444819

  18. Nonvisual spatial navigation fMRI lateralizes mesial temporal lobe epilepsy in a patient with congenital blindness.

    PubMed

    Toller, Gianina; Adhimoolam, Babu; Grunwald, Thomas; Huppertz, Hans-Jürgen; König, Kristina; Jokeit, Hennric

    2015-01-01

    Nonvisual spatial navigation functional magnetic resonance imaging (fMRI) may help clinicians determine memory lateralization in blind individuals with refractory mesial temporal lobe epilepsy (MTLE). We report on an exceptional case of a congenitally blind woman with late-onset left MTLE undergoing presurgical memory fMRI. To activate mesial temporal structures despite the lack of visual memory, the patient was requested to recall familiar routes using nonvisual multisensory and verbal cues. Our findings demonstrate the diagnostic value of a nonvisual fMRI task to lateralize MTLE despite congenital blindness and may therefore contribute to the risk assessment for postsurgical amnesia in rare cases with refractory MTLE and accompanying congenital blindness.

  19. Orbit Maintenance and Navigation of Human Spacecraft at Cislunar Near Rectilinear Halo Orbits

    NASA Technical Reports Server (NTRS)

    Davis, Diane; Bhatt, Sagar; Howell, Kathleen; Jang, Jiann-Woei; Whitley, Ryan; Clark, Fred; Guzzetti, Davide; Zimovan, Emily; Barton, Gregg

    2017-01-01

    Multiple studies have concluded that Earth-Moon libration point orbits are attractive candidates for staging operations. The Near Rectilinear Halo Orbit (NRHO), a member of the Earth-Moon halo orbit family, has been singularly demonstrated to meet multi-mission architectural constraints. In this paper, the challenges associated with operating human spacecraft in the NRHO are evaluated. Navigation accuracies and human vehicle process noise effects are applied to various station keeping strategies in order to obtain a reliable orbit maintenance algorithm. Additionally, the ability to absorb missed burns, construct phasing maneuvers to avoid eclipses and conduct rendezvous and proximity operations are examined.

  20. The Temporal Context Model in Spatial Navigation and Relational Learning: Toward a Common Explanation of Medial Temporal Lobe Function Across Domains

    ERIC Educational Resources Information Center

    Howard, Marc W.; Fotedar, Mrigankka S.; Datey, Aditya V.; Hasselmo, Michael E.

    2005-01-01

    The medial temporal lobe (MTL) has been studied extensively at all levels of analysis, yet its function remains unclear. Theory regarding the cognitive function of the MTL has centered along 3 themes. Different authors have emphasized the role of the MTL in episodic recall, spatial navigation, or relational memory. Starting with the temporal…

  1. The Temporal Context Model in Spatial Navigation and Relational Learning: Toward a Common Explanation of Medial Temporal Lobe Function Across Domains

    ERIC Educational Resources Information Center

    Howard, Marc W.; Fotedar, Mrigankka S.; Datey, Aditya V.; Hasselmo, Michael E.

    2005-01-01

    The medial temporal lobe (MTL) has been studied extensively at all levels of analysis, yet its function remains unclear. Theory regarding the cognitive function of the MTL has centered along 3 themes. Different authors have emphasized the role of the MTL in episodic recall, spatial navigation, or relational memory. Starting with the temporal…

  2. Lesions of the dorsomedial striatum delay spatial learning and render cue-based navigation inflexible in a water maze task in mice.

    PubMed

    Lee, Anni S; André, Jessica M; Pittenger, Christopher

    2014-01-01

    The dorsal striatum is involved in cue-based navigation strategies and in the development of habits. It has been proposed that striatum-dependent cued navigation competes with hippocampus-dependent spatial navigation in some circumstances. We have previously shown that large lesions of the dorsal striatum, as well as impairment of corticostriatal synaptic plasticity in transgenic mice, can enhance spatial learning in a water maze task, presumably by the disruption of competitive interference. However, the dorsal striatum is not a homogeneous structure; both anatomical considerations and experimental studies in various paradigms show that dorsomedial and dorsolateral striatum are functionally distinct, although there is no precise anatomical or neurochemical boundary between them. Here we investigated the effect of restricted excitotoxic lesions of dorsomedial striatum (DMS) on cued and spatial water maze learning. We find that dorsomedial striatal lesions delay spatial learning but permit cued learning. After cued learning, lesioned animals showed inflexible search, resulting in repeated visits to the escape platform-associated cue. These results support a role for the DMS in behavioral flexibility rather than in cue-based navigation.

  3. 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.

  4. Incidental Learning of Links during Navigation: The Role of Visuo-Spatial Capacity

    ERIC Educational Resources Information Center

    Rouet, Jean-Francois; Voros, Zsofia; Pleh, Csaba

    2012-01-01

    We investigated the impact of readers' visuo-spatial (VS) capacity on their incidental learning of page links during the exploration of simple hierarchical hypertextual documents. Forty-three university students were asked to explore a series of hypertexts for a limited period of time. Then the participants were asked to recall the layout and the…

  5. Cognitive Load of Navigating without Vision when Guided by Virtual Sound versus Spatial Language

    ERIC Educational Resources Information Center

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

    2006-01-01

    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")…

  6. Is There a Geometric Module for Spatial Orientation? Insights from a Rodent Navigation Model

    ERIC Educational Resources Information Center

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

    2009-01-01

    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…

  7. Is There a Geometric Module for Spatial Orientation? Insights from a Rodent Navigation Model

    ERIC Educational Resources Information Center

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

    2009-01-01

    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…

  8. Integration of spatial relationships and temporal relationships in humans

    PubMed Central

    Molet, Mikaël; Jozefowiez, Jeremie; Miller, Ralph R.

    2010-01-01

    Three experiments tested human participants on a two-dimensional, computer, landmark-based search task to assess the integration of independently acquired spatial and temporal relationships. Experiment 1 showed that A–B spatial training followed by B–outcome spatial training resulted in spatial integration in such a way that A was effectively associated with the outcome. Experiment 2 showed that A–B spatial and temporal training followed by B–outcome spatial and temporal training resulted in integration that created both spatial and temporal relationships between A and the outcome. Experiment 3 refuted an alternative explanation, one that is based on decision-making speed, to the temporal-integration strategy that was suggested by Experiment 2. These results replicate in humans the observations regarding spatial integration made by Sawa, Leising, and Blaisdell (2005) using a spatial-search task with pigeons, and they extend those observations to temporal integration. PMID:20065346

  9. Interactive navigation-guided ophthalmic plastic surgery: assessment of optical versus electromagnetic modes and role of dynamic reference frame location using navigation-enabled human skulls

    PubMed Central

    Ali, Mohammad Javed; Naik, Milind N; Girish, Chetan Mallikarjuniah; Ali, Mohammad Hasnat; Kaliki, Swathi; Dave, Tarjani Vivek; Dendukuri, Gautam

    2016-01-01

    Aim The aim of this study was to assess the anatomical accuracy of navigation technology in localizing defined anatomic landmarks within the orbit with respect to type of technology (optical versus electromagnetic systems) and position of the dynamic reference marker on the skull (vertex, temporal, parietal, and mastoid) using in vitro navigation-enabled human skulls. The role of this model as a possible learning tool for anatomicoradiological correlations was also assessed. Methods Computed tomography (CT) scans were performed on three cadaveric human skulls using the standard image-guidance acquisition protocols. Thirty-five anatomical landmarks were identified for stereotactic navigation using the image-guided StealthStation S7™ in both electromagnetic and optical modes. Three outcome measures studied were accuracy of anatomical localization and its repeatability, comparisons between the electromagnetic and optical modes in assessing radiological accuracy, and the efficacy of dynamic reference frame (DRF) at different locations on the skull. Results The geometric localization of all the identified anatomical landmarks could be achieved accurately. The Cohen’s kappa agreements between the surgeons were found to be perfect (kappa =0.941) at all predetermined points. There was no difference in anatomical localization between the optical and electromagnetic modes (P≤0.001). Precision for radiological identification did not differ with various positions of the DRF. Skulls with intact anatomical details and careful CT image acquisitions were found to be stereotactically useful. Conclusion Accuracy of anatomic localization within the orbit with navigation technology is equal with optical and electromagnetic system. The location of DRF does not affect the accuracy. Navigation-enabled skull models can be potentially useful as teaching tools for achieving the accurate radiological orientation of orbital and periorbital structures. PMID:27932861

  10. Patterns of activation and de-activation associated with cue-guided spatial navigation: A whole-brain, voxel-based study.

    PubMed

    Salgado-Pineda, Pilar; Landin-Romero, Ramón; Pomes, Ausias; Spanlang, Bernhard; Sarró, Salvador; Salvador, Raymond; Slater, Mel; McKenna, Peter J; Pomarol-Clotet, Edith

    2017-09-01

    Functional imaging studies have implicated the hippocampus and parahippocampal gyrus in cue-guided spatial navigation, but also many other regions. Furthermore, little is known about de-activations that take place during performance of navigation tasks, something that is of interest given that the hippocampus is a component of the default mode network, which de-activates during attention-demanding tasks. In this study 22 healthy subjects underwent whole-brain functional Magnetic Resonance Imaging (fMRI) while they navigated toward a previously learned goal in a virtual reality environment. At a threshold of p<0.05 corrected, the subjects showed a pattern of widespread cortical activations, including the parahippocampal and retrosplenial cortex and also parts of the frontal, temporal and occipital cortex. Hippocampal activation, however, was restricted to the posterior portion of the structure bilaterally. De-activations were seen in the medial frontal cortex and other regions of the default mode network, but not in the posterior cingulate cortex/precuneus. The findings support the involvement of the hippocampus in cue-guided navigation, but suggest that its posterior regions are particularly important. Cue-guided spatial navigation is associated with de-activation in some but not all parts of the default mode network. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  11. Spatial memory and navigation by honeybees on the scale of the foraging range

    PubMed

    Dyer

    1996-01-01

    Honeybees and other nesting animals face the problem of finding their way between their nest and distant feeding sites. Many studies have shown that insects can learn foraging routes in reference to both landmarks and celestial cues, but it is a major puzzle how spatial information obtained from these environmental features is encoded in memory. This paper reviews recent progress by my colleagues and me towards understanding three specific aspects of this problem in honeybees: (1) how bees learn the spatial relationships among widely separated locations in a familiar terrain; (2) how bees learn the pattern of movement of the sun over the day; and (3) whether, and if so how, bees learn the relationships between celestial cues and landmarks.

  12. Following Navigation Instructions Presented Verbally or Spatially: Effects on Training, Retention and Transfer

    DTIC Science & Technology

    2009-01-01

    Maki, 1979; Mou, Zhang, & McNamara, 2004). We might expect that directly presenting the movement sequences spatially would yield the same strategies ...earlier studies (e.g. Barshi & Healy, 2002). For the commands in the verbal condition, a male native English speaker had been recorded giving...every command in a message in order to be scored as correct, they could not use the strategy of end-position seeking, in which they would consider

  13. Functional connections between optic flow areas and navigationally responsive brain regions during goal-directed navigation.

    PubMed

    Sherrill, Katherine R; Chrastil, Elizabeth R; Ross, Robert S; Erdem, Uğur M; Hasselmo, Michael E; Stern, Chantal E

    2015-09-01

    Recent computational models suggest that visual input from optic flow provides information about egocentric (navigator-centered) motion and influences firing patterns in spatially tuned cells during navigation. Computationally, self-motion cues can be extracted from optic flow during navigation. Despite the importance of optic flow to navigation, a functional link between brain regions sensitive to optic flow and brain regions important for navigation has not been established in either humans or animals. Here, we used a beta-series correlation methodology coupled with two fMRI tasks to establish this functional link during goal-directed navigation in humans. Functionally defined optic flow sensitive cortical areas V3A, V6, and hMT+ were used as seed regions. fMRI data was collected during a navigation task in which participants updated position and orientation based on self-motion cues to successfully navigate to an encoded goal location. The results demonstrate that goal-directed navigation requiring updating of position and orientation in the first person perspective involves a cooperative interaction between optic flow sensitive regions V3A, V6, and hMT+ and the hippocampus, retrosplenial cortex, posterior parietal cortex, and medial prefrontal cortex. These functional connections suggest a dynamic interaction between these systems to support goal-directed navigation. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Comparative analysis of movement characteristics during dead-reckoning-based navigation in humans and rats.

    PubMed

    Wallace, Douglas G; Choudhry, Sarwat; Martin, Megan M

    2006-11-01

    Human and rat movement organization was investigated as they searched for randomly located rewards without access to visual information. Under dark conditions, rats foraged for randomly located food pellets (Experiment 1). Blindfolded humans were instructed to search for an ostensible hidden coin using a metal detector (Experiment 2). After locating the food pellet, rats carried it back to the refuge, and after a designated searching time, humans were instructed to return to the start location. Although both species exhibited a high degree of similarity in searching path movement organization and ability to return to the start location, disruption of human searching path organization was associated with impairments in returning to the start location. These results support the vestibular "gain" account of movement organization during dead-reckoning-based navigation.

  15. From brain synapses to systems for learning and memory: Object recognition, spatial navigation, timed conditioning, and movement control.

    PubMed

    Grossberg, Stephen

    2015-09-24

    This article provides an overview of neural models of synaptic learning and memory whose expression in adaptive behavior depends critically on the circuits and systems in which the synapses are embedded. It reviews Adaptive Resonance Theory, or ART, models that use excitatory matching and match-based learning to achieve fast category learning and whose learned memories are dynamically stabilized by top-down expectations, attentional focusing, and memory search. ART clarifies mechanistic relationships between consciousness, learning, expectation, attention, resonance, and synchrony. ART models are embedded in ARTSCAN architectures that unify processes of invariant object category learning, recognition, spatial and object attention, predictive remapping, and eye movement search, and that clarify how conscious object vision and recognition may fail during perceptual crowding and parietal neglect. The generality of learned categories depends upon a vigilance process that is regulated by acetylcholine via the nucleus basalis. Vigilance can get stuck at too high or too low values, thereby causing learning problems in autism and medial temporal amnesia. Similar synaptic learning laws support qualitatively different behaviors: Invariant object category learning in the inferotemporal cortex; learning of grid cells and place cells in the entorhinal and hippocampal cortices during spatial navigation; and learning of time cells in the entorhinal-hippocampal system during adaptively timed conditioning, including trace conditioning. Spatial and temporal processes through the medial and lateral entorhinal-hippocampal system seem to be carried out with homologous circuit designs. Variations of a shared laminar neocortical circuit design have modeled 3D vision, speech perception, and cognitive working memory and learning. A complementary kind of inhibitory matching and mismatch learning controls movement. This article is part of a Special Issue entitled SI: Brain and Memory

  16. Rats exposed prenatally to alcohol exhibit impairment in spatial navigation test.

    PubMed

    Gianoulakis, C

    1990-01-22

    Prenatal exposure to ethanol causes learning disabilities and low I.Q. scores. The objective of the present studies was to investigate whether exposure of rats to ethanol in utero, would induce a deficit in spatial memory in adult life. Pregnant rats were fed with an ethanol diet from day 1 of pregnancy till parturition. Control rats were either pair-fed with an isocaloric sucrose diet or were fed with lab-chow ad libitum. On the first day of birth, offspring exposed to ethanol in utero were placed with a control mother fed with lab-chow, while offspring of the lab-chow fed dams were placed with ethanol-treated dams. At 40, 60 and 90 days postnatally, behavioral testing was performed using the Morris swim maze, a test of spatial memory. Results indicated that the offspring exposed to ethanol in utero presented deficits in spatial memory processes. Ethanol did not completely block the learning of the swim maze task but the alcohol-exposed offspring exhibited longer latencies to perform the task, swam longer distances prior to locating and climbing onto the platform, and when the platform was removed, searched for it in all 4 quadrants of the pool. Restricted caloric intake during gestation and maternal behavior in early postnatal life also induced deficits in the performance on the swim maze task. However, these deficits were mild and short-lasting being absent at 60 and 90 days of age. In contrast, the deficits induced by ethanol were more severe and longer-lasting, being present in adult life.

  17. Auditory spatial processing in the human cortex.

    PubMed

    Salminen, Nelli H; Tiitinen, Hannu; May, Patrick J C

    2012-12-01

    The auditory system codes spatial locations in a way that deviates from the spatial representations found in other modalities. This difference is especially striking in the cortex, where neurons form topographical maps of visual and tactile space but where auditory space is represented through a population rate code. In this hemifield code, sound source location is represented in the activity of two widely tuned opponent populations, one tuned to the right and the other to the left side of auditory space. Scientists are only beginning to uncover how this coding strategy adapts to various spatial processing demands. This review presents the current understanding of auditory spatial processing in the cortex. To this end, the authors consider how various implementations of the hemifield code may exist within the auditory cortex and how these may be modulated by the stimulation and task context. As a result, a coherent set of neural strategies for auditory spatial processing emerges.

  18. Neuropsychology of environmental navigation in humans: review and meta-analysis of FMRI studies in healthy participants.

    PubMed

    Boccia, Maddalena; Nemmi, Federico; Guariglia, Cecilia

    2014-06-01

    In the past 20 years, many studies in the cognitive neurosciences have analyzed human ability to navigate in recently learned and familiar environments by investigating the cognitive processes involved in successful navigation. In this study, we reviewed the main experimental paradigms and made a cognitive-oriented meta-analysis of fMRI studies of human navigation to underline the importance of the experimental designs and cognitive tasks used to assess navigational skills. We performed a general activation likelihood estimation (ALE) meta-analysis of 66 fMRI experiments to identify the neural substrates underpinning general aspects of human navigation. Four individual ALE analyses were performed to identify the neural substrates of different experimental paradigms (i.e., familiar vs. recently learned environments) and different navigational strategies (allocentric vs. egocentric). Results of the general ALE analysis highlighted a wide network of areas with clusters in the occipital, parietal, frontal and temporal lobes, especially in the parahippocampal cortex. Familiar environments seem to be processed by an extended temporal-frontal network, whereas recently learned environments require activation in the parahippocampal cortex and the parietal and occipital lobes. Allocentric strategy is subtended by the same areas as egocentric strategy, but the latter elicits greater activation in the right precuneus, middle occipital lobe and angular gyrus. Our results suggest that different neural correlates are involved in recalling a well-learned or recently acquired environment and that different networks of areas subtend egocentric and allocentric strategies.

  19. Reference frames in learning from maps and navigation.

    PubMed

    Meilinger, Tobias; Frankenstein, Julia; Watanabe, Katsumi; Bülthoff, Heinrich H; Hölscher, Christoph

    2015-11-01

    In everyday life, navigators often consult a map before they navigate to a destination (e.g., a hotel, a room, etc.). However, not much is known about how humans gain spatial knowledge from seeing a map and direct navigation together. In the present experiments, participants learned a simple multiple corridor space either from a map only, only from walking through the virtual environment, first from the map and then from navigation, or first from navigation and then from the map. Afterwards, they conducted a pointing task from multiple body orientations to infer the underlying reference frames. We constructed the learning experiences in a way such that map-only learning and navigation-only learning triggered spatial memory organized along different reference frame orientations. When learning from maps before and during navigation, participants employed a map- rather than a navigation-based reference frame in the subsequent pointing task. Consequently, maps caused the employment of a map-oriented reference frame found in memory for highly familiar urban environments ruling out explanations from environmental structure or north preference. When learning from navigation first and then from the map, the pattern of results reversed and participants employed a navigation-based reference frame. The priority of learning order suggests that despite considerable difference between map and navigation learning participants did not use the more salient or in general more useful information, but relied on the reference frame established first.

  20. Plasticity of human spatial cognition: spatial language and cognition covary across cultures.

    PubMed

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

    2011-04-01

    The present paper explores cross-cultural variation in spatial cognition by comparing spatial reconstruction tasks by Dutch and Namibian elementary school children. These two communities differ in the way they predominantly express spatial relations in language. Four experiments investigate cognitive strategy preferences across different levels of task-complexity and instruction. Data show a correlation between dominant linguistic spatial frames of reference and performance patterns in non-linguistic spatial memory tasks. This correlation is shown to be stable across an increase of complexity in the spatial array. When instructed to use their respective non-habitual cognitive strategy, participants were not easily able to switch between strategies and their attempts to do so impaired their performance. These results indicate a difference not only in preference but also in competence and suggest that spatial language and non-linguistic preferences and competences in spatial cognition are systematically aligned across human populations.

  1. Predictability in orbital reconstruction. A human cadaver study, part III: Implant-oriented navigation for optimized reconstruction.

    PubMed

    Dubois, Leander; Essig, Harald; Schreurs, Ruud; Jansen, Jesper; Maal, Thomas J J; Gooris, Peter J J; Becking, Alfred G

    2015-12-01

    Navigation-assisted orbital reconstruction remains a challenge, because the surgeon focuses on a two-dimensional multiplanar view in relation to the preoperative planning. This study explored the addition of navigation markers in the implant design for three-dimensional (3D) orientation of the actual implant position relative to the preoperative planning for more fail-safe and consistent results. Pre-injury computed tomography (CT) was performed for 10 orbits in human cadavers, and complex orbital fractures (Class III/IV) were created. The orbits were reconstructed using preformed orbital mesh through a transconjunctival approach under image-guided navigation and navigation by referencing orientating markers in the implant design. Ideal implant positions were planned using preoperative CT scans. Implant placement accuracy was evaluated by comparing the planned and realized implant positions. Significantly better translation (3.53 mm vs. 1.44 mm, p = 0.001) and rotation (pitch: -1.7° vs. -2.2°, P = 0.52; yaw: 10.9° vs. 5.9°, P = 0.02; roll: -2.2° vs. -0.5°, P = 0.16) of the placed implant relative to the planned position were obtained by implant-oriented navigation. Navigation-assisted surgery can be improved by using navigational markers on the orbital implant for orientation, resulting in fail-safe reconstruction of complex orbital defects and consistent implant positioning.

  2. Hippocampal slow EEG frequencies during NREM sleep are involved in spatial memory consolidation in humans.

    PubMed

    Moroni, Fabio; Nobili, Lino; Iaria, Giuseppe; Sartori, Ivana; Marzano, Cristina; Tempesta, Daniela; Proserpio, Paola; Lo Russo, Giorgio; Gozzo, Francesca; Cipolli, Carlo; De Gennaro, Luigi; Ferrara, Michele

    2014-10-01

    The hypothesis that sleep is instrumental in the process of memory consolidation is currently largely accepted. Hippocampal formation is involved in the acquisition of declarative memories and particularly of spatial memories. Nevertheless, although largely investigated in rodents, the relations between spatial memory and hippocampal EEG activity have been scarcely studied in humans. Aimed to evaluate the effects of spatial learning on human hippocampal sleep EEG activity, we recorded hippocampal Stereo-EEG (SEEG) in a group of refractory epilepsy patients undergoing presurgical clinical evaluation, after a training on a spatial navigation task. We observed that hippocampal high-delta (2-4 Hz range) activity increases during the first NREM episode after learning compared to the baseline night. Moreover, the amount of hippocampal NREM high-delta power was correlated with task performance at retest. The effect involved only the hippocampal EEG frequencies inasmuch no differences were observed at the neocortical electrodes and in the traditional polysomnographic measures. The present findings support the crucial role of hippocampal slow EEG frequencies during sleep in the memory consolidation processes. More generally, together with previous results, they suggest that slow frequency rhythms are a fundamental characteristic of human hippocampal EEG during both sleep and wakefulness, and are related to the consolidation of different types of memories.

  3. A New Electromagnetic Navigation System for Pedicle Screws Placement: A Human Cadaver Study at the Lumbar Spine

    PubMed Central

    Hahn, Patrick; Oezdemir, Semih; Komp, Martin; Giannakopoulos, Athanasios; Heikenfeld, Roderich; Kasch, Richard; Merk, Harry; Godolias, Georgios; Ruetten, Sebastian

    2015-01-01

    Introduction Technical developments for improving the safety and accuracy of pedicle screw placement play an increasingly important role in spine surgery. In addition to the standard techniques of free-hand placement and fluoroscopic navigation, the rate of complications is reduced by 3D fluoroscopy, cone-beam CT, intraoperative CT/MRI, and various other navigation techniques. Another important aspect that should be emphasized is the reduction of intraoperative radiation exposure for personnel and patient. The aim of this study was to investigate the accuracy of a new navigation system for the spine based on an electromagnetic field. Material and Method Twenty pedicle screws were placed in the lumbar spine of human cadavers using EMF navigation. Navigation was based on data from a preoperative thin-slice CT scan. The cadavers were positioned on a special field generator and the system was matched using a patient tracker on the spinous process. Navigation was conducted using especially developed instruments that can be tracked in the electromagnetic field. Another thin-slice CT scan was made postoperatively to assess the result. The evaluation included the position of the screws in the direction of trajectory and any injury to the surrounding cortical bone. The results were classified in 5 groups: grade 1: ideal screw position in the center of the pedicle with no cortical bone injury; grade 2: acceptable screw position, cortical bone injury with cortical penetration ≤ 2 mm; grade 3: cortical bone injury with cortical penetration 2,1-4 mm, grad 4: cortical bone injury with cortical penetration 4,1-6 mm, grade 5: cortical bone injury with cortical penetration >6 mm. Results The initial evaluation of the system showed good accuracy for the lumbar spine (65% grade 1, 20% grade 2, 15% grade 3, 0% grade 4, 0% grade 5). A comparison of the initial results with other navigation techniques in literature (CT navigation, 2D fluoroscopic navigation) shows that the accuracy of

  4. A New Electromagnetic Navigation System for Pedicle Screws Placement: A Human Cadaver Study at the Lumbar Spine.

    PubMed

    Hahn, Patrick; Oezdemir, Semih; Komp, Martin; Giannakopoulos, Athanasios; Heikenfeld, Roderich; Kasch, Richard; Merk, Harry; Godolias, Georgios; Ruetten, Sebastian

    2015-01-01

    Technical developments for improving the safety and accuracy of pedicle screw placement play an increasingly important role in spine surgery. In addition to the standard techniques of free-hand placement and fluoroscopic navigation, the rate of complications is reduced by 3D fluoroscopy, cone-beam CT, intraoperative CT/MRI, and various other navigation techniques. Another important aspect that should be emphasized is the reduction of intraoperative radiation exposure for personnel and patient. The aim of this study was to investigate the accuracy of a new navigation system for the spine based on an electromagnetic field. Twenty pedicle screws were placed in the lumbar spine of human cadavers using EMF navigation. Navigation was based on data from a preoperative thin-slice CT scan. The cadavers were positioned on a special field generator and the system was matched using a patient tracker on the spinous process. Navigation was conducted using especially developed instruments that can be tracked in the electromagnetic field. Another thin-slice CT scan was made postoperatively to assess the result. The evaluation included the position of the screws in the direction of trajectory and any injury to the surrounding cortical bone. The results were classified in 5 groups: grade 1: ideal screw position in the center of the pedicle with no cortical bone injury; grade 2: acceptable screw position, cortical bone injury with cortical penetration ≤ 2 mm; grade 3: cortical bone injury with cortical penetration 2,1-4 mm, grad 4: cortical bone injury with cortical penetration 4,1-6 mm, grade 5: cortical bone injury with cortical penetration >6 mm. The initial evaluation of the system showed good accuracy for the lumbar spine (65% grade 1, 20% grade 2, 15% grade 3, 0% grade 4, 0% grade 5). A comparison of the initial results with other navigation techniques in literature (CT navigation, 2D fluoroscopic navigation) shows that the accuracy of this system is comparable. EMF

  5. Real-time cannula navigation in biological tissue with high temporal and spatial resolution based on impedance spectroscopy.

    PubMed

    Trebbels, Dennis; Jugl, Michael; Zengerle, Roland

    2010-01-01

    In many medical applications a well-directed positioning of a cannula in body tissue is mandatory. Especially the accurate placing of the cannula tip in the tissue is important for efficient drug delivery or for accessing blood vessels and nerves. This paper presents a new approach for a universal cannula navigation system based on tissue classification on the cannula tip by impedance spectroscopy. The cannula serves as coaxial, open ended waveguide which is connected to remote measurement equipment. Objective of the new system is to reach a high spatial and temporal resolution for dynamic cannula guidance. Therefore the proposed coaxial cannula design has been analyzed by Finite Element Simulation to investigate the sensitivity of the cannula tip. For fast tissue impedance spectrum measurement the Time-Domain-Reflectometry method is used in order to achieve a high temporal resolution. Measurement data derived in the laboratory is analyzed and interpreted using the general Cole-Cole model for tissue. Based on the results we propose to use a chirp signal for impedance measurement in order to improve the sensitivity of the system towards specific tissue properties.

  6. Spatial and temporal dynamics of suspended particle characteristics and composition in Navigation Pool 19 of the Upper Mississippi River

    USGS Publications Warehouse

    Milde, Amanda S.

    2017-01-01

    Suspended particles are an essential component of large rivers influencing channel geomorphology, biogeochemical cycling of nutrients, and food web resources. The Upper Mississippi River (UMR) is a large floodplain river that exhibits pronounced spatiotemporal variation in environmental conditions and biota, providing an ideal environment for investigating dynamics of suspended particles in large river ecosystems. Here we investigated two questions: (1) How do suspended particle characteristics (e.g., size and morphology) vary temporally and spatially? and (2) What environmental variables have the strongest association with particle characteristics? Water sampling was conducted in June, August, and September of 2013 and 2014 in Navigation Pool 19 of the UMR. A FlowCAM particle imaging system was used to enumerate and measure particles 53–300 µm in diameter for size and shape characteristics (e.g., volume, elongation, and symmetry). Suspended particle characteristics varied considerably over space and time and were strongly associated with discharge and concentrations of nitrate + nitrite (NO3-) and soluble reactive phosphorous (SRP). Particle characteristics in backwaters were distinct from those in other habitats for most of the study period, likely due to reduced hydrologic connectivity and higher biotic production in backwaters. During low discharge, phytoplankton and zooplankton made up relatively greater proportions of the observed particles. Concurrently during low discharge, concentrations of chlorophyll, volatile suspended solids, and total phosphorous were higher. Our results suggest that there are complex interactions among space, time, discharge, and other environmental variables (e.g. water nutrients) which drive suspended particle dynamics in large rivers.

  7. Modeling goal-directed spatial navigation in the rat based on physiological data from the hippocampal formation.

    PubMed

    Koene, Randal A; Gorchetchnikov, Anatoli; Cannon, Robert C; Hasselmo, Michael E

    2003-01-01

    We investigated the importance of hippocampal theta oscillations and the significance of phase differences of theta modulation in the cortical regions that are involved in goal-directed spatial navigation. Our models used representations of entorhinal cortex layer III (ECIII), hippocampus and prefrontal cortex (PFC) to guide movements of a virtual rat in a virtual environment. The model encoded representations of the environment through long-term potentiation of excitatory recurrent connections between sequentially spiking place cells in ECIII and CA3. This encoding required buffering of place cell activity, which was achieved by a short-term memory (STM) in EC that was regulated by theta modulation and allowed synchronized reactivation with encoding phases in ECIII and CA3. Inhibition at a specific theta phase deactivated the oldest item in the buffer when new input was presented to a full STM buffer. A 180 degrees phase difference separated retrieval and encoding in ECIII and CA3, which enabled us to simulate data on theta phase precession of place cells. Retrieval of known paths was elicited in ECIII by input at the retrieval phase from PFC working memory for goal location, requiring strict theta phase relationships with PFC. Known locations adjacent to the virtual rat were retrieved in CA3. Together, input from ECIII and CA3 activated predictive spiking in cells in CA1 for the next desired place on a shortest path to a goal. Consistent with data, place cell activity in CA1 and CA3 showed smaller place fields than in ECIII.

  8. Assisted navigation based on shared-control, using discrete and sparse human-machine interfaces.

    PubMed

    Lopes, Ana C; Nunes, Urbano; Vaz, Luis; Vaz, Luís

    2010-01-01

    This paper presents a shared-control approach for Assistive Mobile Robots (AMR), which depends on the user's ability to navigate a semi-autonomous powered wheelchair, using a sparse and discrete human-machine interface (HMI). This system is primarily intended to help users with severe motor disabilities that prevent them to use standard human-machine interfaces. Scanning interfaces and Brain Computer Interfaces (BCI), characterized to provide a small set of commands issued sparsely, are possible HMIs. This shared-control approach is intended to be applied in an Assisted Navigation Training Framework (ANTF) that is used to train users' ability in steering a powered wheelchair in an appropriate manner, given the restrictions imposed by their limited motor capabilities. A shared-controller based on user characterization, is proposed. This controller is able to share the information provided by the local motion planning level with the commands issued sparsely by the user. Simulation results of the proposed shared-control method, are presented.

  9. Retrosplenial Cortical Neurons Encode Navigational Cues, Trajectories and Reward Locations During Goal Directed Navigation.

    PubMed

    Vedder, Lindsey C; Miller, Adam M P; Harrison, Marc B; Smith, David M

    2016-07-29

    The retrosplenial cortex (RSC) plays an important role in memory and spatial navigation. It shares functional similarities with the hippocampus, including the presence of place fields and lesion-induced impairments in spatial navigation, and the RSC is an important source of visual-spatial input to the hippocampus. Recently, the RSC has been the target of intense scrutiny among investigators of human memory and navigation. fMRI and lesion data suggest an RSC role in the ability to use landmarks to navigate to goal locations. However, no direct neurophysiological evidence of encoding navigational cues has been reported so the specific RSC contribution to spatial cognition has been uncertain. To examine this, we trained rats on a T-maze task in which the reward location was explicitly cued by a flashing light and we recorded RSC neurons as the rats learned. We found that RSC neurons rapidly encoded the light cue. Additionally, RSC neurons encoded the reward and its location, and they showed distinct firing patterns along the left and right trajectories to the goal. These responses may provide key information for goal-directed navigation, and the loss of these signals may underlie navigational impairments in subjects with RSC damage.

  10. Human fronto-parietal and parieto-hippocampal pathways represent behavioral priorities in multiple spatial reference frames

    PubMed Central

    Szczepanski, Sara M; Saalmann, Yuri B

    2013-01-01

    We represent behaviorally relevant information in different spatial reference frames in order to interact effectively with our environment. For example, we need an egocentric (e.g., body-centered) reference frame to specify limb movements and an allocentric (e.g., world-centered) reference frame to navigate from one location to another. Posterior parietal cortex (PPC) is vital for performing transformations between these different coordinate systems. Here, we review evidence for multiple pathways in the human brain, from PPC to motor, premotor, and supplementary motor areas, as well as to structures in the medial temporal lobe. These connections are important for transformations between egocentric reference frames to facilitate sensory-guided action, or from egocentric to allocentric reference frames to facilitate spatial navigation. PMID:24322829

  11. Using APEX to Model Anticipated Human Error: Analysis of a GPS Navigational Aid

    NASA Technical Reports Server (NTRS)

    VanSelst, Mark; Freed, Michael; Shefto, Michael (Technical Monitor)

    1997-01-01

    The interface development process can be dramatically improved by predicting design facilitated human error at an early stage in the design process. The approach we advocate is to SIMULATE the behavior of a human agent carrying out tasks with a well-specified user interface, ANALYZE the simulation for instances of human error, and then REFINE the interface or protocol to minimize predicted error. This approach, incorporated into the APEX modeling architecture, differs from past approaches to human simulation in Its emphasis on error rather than e.g. learning rate or speed of response. The APEX model consists of two major components: (1) a powerful action selection component capable of simulating behavior in complex, multiple-task environments; and (2) a resource architecture which constrains cognitive, perceptual, and motor capabilities to within empirically demonstrated limits. The model mimics human errors arising from interactions between limited human resources and elements of the computer interface whose design falls to anticipate those limits. We analyze the design of a hand-held Global Positioning System (GPS) device used for radical and navigational decisions in small yacht recalls. The analysis demonstrates how human system modeling can be an effective design aid, helping to accelerate the process of refining a product (or procedure).

  12. Using APEX to Model Anticipated Human Error: Analysis of a GPS Navigational Aid

    NASA Technical Reports Server (NTRS)

    VanSelst, Mark; Freed, Michael; Shefto, Michael (Technical Monitor)

    1997-01-01

    The interface development process can be dramatically improved by predicting design facilitated human error at an early stage in the design process. The approach we advocate is to SIMULATE the behavior of a human agent carrying out tasks with a well-specified user interface, ANALYZE the simulation for instances of human error, and then REFINE the interface or protocol to minimize predicted error. This approach, incorporated into the APEX modeling architecture, differs from past approaches to human simulation in Its emphasis on error rather than e.g. learning rate or speed of response. The APEX model consists of two major components: (1) a powerful action selection component capable of simulating behavior in complex, multiple-task environments; and (2) a resource architecture which constrains cognitive, perceptual, and motor capabilities to within empirically demonstrated limits. The model mimics human errors arising from interactions between limited human resources and elements of the computer interface whose design falls to anticipate those limits. We analyze the design of a hand-held Global Positioning System (GPS) device used for radical and navigational decisions in small yacht recalls. The analysis demonstrates how human system modeling can be an effective design aid, helping to accelerate the process of refining a product (or procedure).

  13. Auditory Spatial Attention Representations in the Human Cerebral Cortex

    PubMed Central

    Kong, Lingqiang; Michalka, Samantha W.; Rosen, Maya L.; Sheremata, Summer L.; Swisher, Jascha D.; Shinn-Cunningham, Barbara G.; Somers, David C.

    2014-01-01

    Auditory spatial attention serves important functions in auditory source separation and selection. Although auditory spatial attention mechanisms have been generally investigated, the neural substrates encoding spatial information acted on by attention have not been identified in the human neocortex. We performed functional magnetic resonance imaging experiments to identify cortical regions that support auditory spatial attention and to test 2 hypotheses regarding the coding of auditory spatial attention: 1) auditory spatial attention might recruit the visuospatial maps of the intraparietal sulcus (IPS) to create multimodal spatial attention maps; 2) auditory spatial information might be encoded without explicit cortical maps. We mapped visuotopic IPS regions in individual subjects and measured auditory spatial attention effects within these regions of interest. Contrary to the multimodal map hypothesis, we observed that auditory spatial attentional modulations spared the visuotopic maps of IPS; the parietal regions activated by auditory attention lacked map structure. However, multivoxel pattern analysis revealed that the superior temporal gyrus and the supramarginal gyrus contained significant information about the direction of spatial attention. These findings support the hypothesis that auditory spatial information is coded without a cortical map representation. Our findings suggest that audiospatial and visuospatial attention utilize distinctly different spatial coding schemes. PMID:23180753

  14. Auditory spatial attention representations in the human cerebral cortex.

    PubMed

    Kong, Lingqiang; Michalka, Samantha W; Rosen, Maya L; Sheremata, Summer L; Swisher, Jascha D; Shinn-Cunningham, Barbara G; Somers, David C

    2014-03-01

    Auditory spatial attention serves important functions in auditory source separation and selection. Although auditory spatial attention mechanisms have been generally investigated, the neural substrates encoding spatial information acted on by attention have not been identified in the human neocortex. We performed functional magnetic resonance imaging experiments to identify cortical regions that support auditory spatial attention and to test 2 hypotheses regarding the coding of auditory spatial attention: 1) auditory spatial attention might recruit the visuospatial maps of the intraparietal sulcus (IPS) to create multimodal spatial attention maps; 2) auditory spatial information might be encoded without explicit cortical maps. We mapped visuotopic IPS regions in individual subjects and measured auditory spatial attention effects within these regions of interest. Contrary to the multimodal map hypothesis, we observed that auditory spatial attentional modulations spared the visuotopic maps of IPS; the parietal regions activated by auditory attention lacked map structure. However, multivoxel pattern analysis revealed that the superior temporal gyrus and the supramarginal gyrus contained significant information about the direction of spatial attention. These findings support the hypothesis that auditory spatial information is coded without a cortical map representation. Our findings suggest that audiospatial and visuospatial attention utilize distinctly different spatial coding schemes.

  15. Compressive spatial summation in human visual cortex

    PubMed Central

    Winawer, Jonathan; Mezer, Aviv; Wandell, Brian A.

    2013-01-01

    Neurons within a small (a few cubic millimeters) region of visual cortex respond to stimuli within a restricted region of the visual field. Previous studies have characterized the population response of such neurons using a model that sums contrast linearly across the visual field. In this study, we tested linear spatial summation of population responses using blood oxygenation level-dependent (BOLD) functional MRI. We measured BOLD responses to a systematic set of contrast patterns and discovered systematic deviation from linearity: the data are more accurately explained by a model in which a compressive static nonlinearity is applied after linear spatial summation. We found that the nonlinearity is present in early visual areas (e.g., V1, V2) and grows more pronounced in relatively anterior extrastriate areas (e.g., LO-2, VO-2). We then analyzed the effect of compressive spatial summation in terms of changes in the position and size of a viewed object. Compressive spatial summation is consistent with tolerance to changes in position and size, an important characteristic of object representation. PMID:23615546

  16. How Simple Hypothetical-Choice Experiments Can Be Utilized to Learn Humans' Navigational Escape Decisions in Emergencies.

    PubMed

    Haghani, Milad; Sarvi, Majid; Shahhoseini, Zahra; Boltes, Maik

    2016-01-01

    How humans resolve non-trivial tradeoffs in their navigational choices between the social interactions (e.g., the presence and movements of others) and the physical factors (e.g., spatial distances, route visibility) when escaping from threats in crowded confined spaces? The answer to this question has major implications for the planning of evacuations and the safety of mass gatherings as well as the design of built environments. Due to the challenges of collecting behavioral data from naturally-occurring evacuation settings, laboratory-based virtual-evacuation experiments have been practiced in a number of studies. This class of experiments faces the traditional question of contextual bias and generalizability: How reliably can we infer humans' behavior from decisions made in hypothetical settings? Here, we address these questions by making a novel link between two different forms of empirical observations. We conduct hypothetical emergency exit-choice experiments framed as simple pictures, and then mimic those hypothetical scenarios in more realistic fashions through staging mock evacuation trials with actual crowds. Econometric choice models are estimated based on the observations made in both experimental contexts. The models are contrasted with each other from a number of perspectives including their predictions as well as the sign, magnitude, statistical significance, person-to-person variations (reflecting individuals' perception/preference differences) and the scale (reflecting context-dependent decision randomness) of their inferred parameters. Results reveal a surprising degree of resemblance between the models derived from the two contexts. Most strikingly, they produce fairly similar prediction probabilities whose differences average less than 10%. There is also unexpected consensus between the inferences derived from both experimental sources on many aspects of people's behavior notably in terms of the perception of social interactions. Results show

  17. 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.

  18. Posterior neocortical (visual cortex) lesions in the rat impair matching-to-place navigation in a swimming pool: a reevaluation of cortical contributions to spatial behavior using a new assessment of spatial versus nonspatial behavior.

    PubMed

    Whishaw, Ian Q

    2004-11-05

    In the face of contradictory findings on the role of visual cortex contributions to spatial behavior, the present study evaluated the ability of rats with primary visual cortex (area 17) lesions to learn spatial problems in a swimming pool. Because the solution to any spatial learning problem consists of acquiring at least two primary elements of a task, task procedures and spatial learning, the study, in addition to assessing spatial ability on a place task, used two training/testing methods to identify the nature of the spatial impairment associated with visual cortex lesions. Non-spatial training consisted of learning to find a platform in the dark and spatial training consisted of a series of matching-to-place problems. The results confirmed that although rats with visual cortex lesions were impaired on place learning, the deficit was partially ameliorated by non-spatial training given following the lesion, and completely ameliorated by non-spatial training given before the lesion. Nevertheless, all visual cortex groups failed to show a quadrant preference on a probe trial and displayed a profound impairment in matching-to-place learning. This definitive demonstration that appropriate testing methods can reveal a failure in spatial behavior following visual cortex lesions is consistent with the idea that primary visual cortex is required in spatial navigation.

  19. Spatial and temporal dynamics of suspended particle characteristics and composition in Navigation Pool 19 of the Upper Mississippi River

    USGS Publications Warehouse

    Milde, Amanda S.; Richardson, William B.; Strauss, Eric A.; Larson, James H.; Vallazza, Jon; Knights, Brent C.

    2017-01-01

    Suspended particles are an essential component of large rivers influencing channel geomorphology, biogeochemical cycling of nutrients, and food web resources. The Upper Mississippi River is a large floodplain river that exhibits pronounced spatiotemporal variation in environmental conditions and biota, providing an ideal environment for investigating dynamics of suspended particles in large river ecosystems. Here we investigated two questions: (i) How do suspended particle characteristics (e.g. size and morphology) vary temporally and spatially? and (ii) What environmental variables have the strongest association with particle characteristics? Water sampling was conducted in June, August, and September of 2013 and 2014 in Navigation Pool 19 of the Upper Mississippi River. A FlowCAM® (Flow Cytometer and Microscope) particle imaging system was used to enumerate and measure particles 53–300 μm in diameter for size and shape characteristics (e.g. volume, elongation, and symmetry). Suspended particle characteristics varied considerably over space and time and were strongly associated with discharge and concentrations of nitrate + nitrite (NO3−) and soluble reactive phosphorus. Particle characteristics in backwaters were distinct from those in other habitats for most of the study period, likely due to reduced hydrologic connectivity and higher biotic production in backwaters. During low discharge, phytoplankton and zooplankton made up relatively greater proportions of the observed particles. Concurrently during low discharge, concentrations of chlorophyll, volatile suspended solids, and total phosphorus were higher. Our results suggest that there are complex interactions among space, time, discharge, and other environmental variables (e.g. water nutrients), which drive suspended particle dynamics in large rivers.

  20. A Layered Approach for Robust Spatial Virtual Human Pose Reconstruction Using a Still Image

    PubMed Central

    Guo, Chengyu; Ruan, Songsong; Liang, Xiaohui; Zhao, Qinping

    2016-01-01

    Pedestrian detection and human pose estimation are instructive for reconstructing a three-dimensional scenario and for robot navigation, particularly when large amounts of vision data are captured using various data-recording techniques. Using an unrestricted capture scheme, which produces occlusions or breezing, the information describing each part of a human body and the relationship between each part or even different pedestrians must be present in a still image. Using this framework, a multi-layered, spatial, virtual, human pose reconstruction framework is presented in this study to recover any deficient information in planar images. In this framework, a hierarchical parts-based deep model is used to detect body parts by using the available restricted information in a still image and is then combined with spatial Markov random fields to re-estimate the accurate joint positions in the deep network. Then, the planar estimation results are mapped onto a virtual three-dimensional space using multiple constraints to recover any deficient spatial information. The proposed approach can be viewed as a general pre-processing method to guide the generation of continuous, three-dimensional motion data. The experiment results of this study are used to describe the effectiveness and usability of the proposed approach. PMID:26907289

  1. Task-dependent activations of human auditory cortex during spatial discrimination and spatial memory tasks.

    PubMed

    Rinne, Teemu; Koistinen, Sonja; Talja, Suvi; Wikman, Patrik; Salonen, Oili

    2012-02-15

    In the present study, we applied high-resolution functional magnetic resonance imaging (fMRI) of the human auditory cortex (AC) and adjacent areas to compare activations during spatial discrimination and spatial n-back memory tasks that were varied parametrically in difficulty. We found that activations in the anterior superior temporal gyrus (STG) were stronger during spatial discrimination than during spatial memory, while spatial memory was associated with stronger activations in the inferior parietal lobule (IPL). We also found that wide AC areas were strongly deactivated during the spatial memory tasks. The present AC activation patterns associated with spatial discrimination and spatial memory tasks were highly similar to those obtained in our previous study comparing AC activations during pitch discrimination and pitch memory (Rinne et al., 2009). Together our previous and present results indicate that discrimination and memory tasks activate anterior and posterior AC areas differently and that this anterior-posterior division is present both when these tasks are performed on spatially invariant (pitch discrimination vs. memory) or spatially varying (spatial discrimination vs. memory) sounds. These results also further strengthen the view that activations of human AC cannot be explained only by stimulus-level parameters (e.g., spatial vs. nonspatial stimuli) but that the activations observed with fMRI are strongly dependent on the characteristics of the behavioral task. Thus, our results suggest that in order to understand the functional structure of AC a more systematic investigation of task-related factors affecting AC activations is needed. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. Control algorithms for autonomous robot navigation

    SciTech Connect

    Jorgensen, C.C.

    1985-09-20

    This paper examines control algorithm requirements for autonomous robot navigation outside laboratory environments. Three aspects of navigation are considered: navigation control in explored terrain, environment interactions with robot sensors, and navigation control in unanticipated situations. Major navigation methods are presented and relevance of traditional human learning theory is discussed. A new navigation technique linking graph theory and incidental learning is introduced.

  3. Spatial coherence in human tissue: implications for imaging and measurement

    PubMed Central

    Pinton, Gianmarco; Trahey, Gregg; Dahl, Jeremy

    2014-01-01

    The spatial coherence properties of the signal backscattered by human tissue and measured by an ultrasound transducer array are investigated. Fourier acoustics are used to describe the propagation of ultrasound through a model of tissue that includes reverberation and random scatterering in the imaging plane. The theoretical development describes how the near-field tissue layer, transducer aperture properties, and reflectivity function at the focus reduce the spatial coherence of the imaging wave measured at the transducer surface. Simulations are used to propagate the acoustic field through a histologically characterized sample of the human abdomen and to validate the theoretical predictions. In vivo measurements performed with a diagnostic ultrasound scanner demonstrate that simulations and theory closely match the measured spatial coherence characteristics in the human body across the transducer array’s entire spatial extent. The theoretical framework and simulations are then used to describe the physics of spatial coherence imaging, a type of ultrasound imaging that measures coherence properties instead of echo brightness. The same echo data from an F/2 transducer was used to generate B-mode and short lag spatial coherence images. For an anechoic lesion at the focus the contrast to noise ratio is 1.21 for conventional B-mode imaging and 1.95 for spatial coherence imaging. It is shown that the contrast in spatial coherence imaging depends on the properties of the near-field tissue layer and the backscattering function in the focal plane. PMID:25474774

  4. Plasticity in human sound localization induced by compressed spatial vision.

    PubMed

    Zwiers, Marcel P; Van Opstal, A John; Paige, Gary D

    2003-02-01

    Auditory and visual target locations are encoded differently in the brain, but must be co-calibrated to maintain cross-sensory concordance. Mechanisms that adjust spatial calibration across modalities have been described (for example, prism adaptation in owls), though rudimentarily in humans. We quantified the adaptation of human sound localization in response to spatially compressed vision (0.5x lenses for 2-3 days). This induced a corresponding compression of auditory localization that was most pronounced for azimuth (minimal for elevation) and was restricted to the visual field of the lenses. Sound localization was also affected outside the field of visual-auditory interaction (shifted centrally, not compressed). These results suggest that spatially modified vision induces adaptive changes in adult human sound localization, including novel mechanisms that account for spatial compression. Findings are consistent with a model in which the central processing of sound location is encoded by recruitment rather than by a place code.

  5. “Taller and Shorter”: Human 3-D Spatial Memory Distorts Familiar Multilevel Buildings

    PubMed Central

    Brandt, Thomas; Huber, Markus; Schramm, Hannah; Kugler, Günter; Dieterich, Marianne; Glasauer, Stefan

    2015-01-01

    Animal experiments report contradictory findings on the presence of a behavioural and neuronal anisotropy exhibited in vertical and horizontal capabilities of spatial orientation and navigation. We performed a pointing experiment in humans on the imagined 3-D direction of the location of various invisible goals that were distributed horizontally and vertically in a familiar multilevel hospital building. The 21 participants were employees who had worked for years in this building. The hypothesis was that comparison of the experimentally determined directions and the true directions would reveal systematic inaccuracy or dimensional anisotropy of the localizations. The study provides first evidence that the internal representation of a familiar multilevel building was distorted compared to the dimensions of the true building: vertically 215% taller and horizontally 51% shorter. This was not only demonstrated in the mathematical reconstruction of the mental model based on the analysis of the pointing experiments but also by the participants’ drawings of the front view and the ground plan of the building. Thus, in the mental model both planes were altered in different directions: compressed for the horizontal floor plane and stretched for the vertical column plane. This could be related to human anisotropic behavioural performance of horizontal and vertical navigation in such buildings. PMID:26509927

  6. Telencephalic Neuronal Activation Associated with Spatial Memory in the Terrestrial Toad Rhinella arenarum: Participation of the Medial Pallium during Navigation by Geometry.

    PubMed

    Sotelo, María Inés; Daneri, M Florencia; Bingman, Verner Peter; Muzio, Rubén N

    2016-01-01

    Amphibians are central to discussions of vertebrate evolution because they represent the transition from aquatic to terrestrial life, a transition with profound consequences for the selective pressures shaping brain evolution. Spatial navigation is one class of behavior that has attracted the interest of comparative neurobiologists because of the relevance of the medial pallium/hippocampus, yet, surprisingly, in this regard amphibians have been sparsely investigated. In the current study, we trained toads to locate a water goal relying on the boundary geometry of a test environment (Geometry-Only) or boundary geometry coupled with a prominent, visual feature cue (Geometry-Feature). Once learning had been achieved, the animals were given one last training session and their telencephali were processed for c-Fos activation. Compared to control toads exposed to the test environment for the first time, geometry-only toads were found to have increased neuronal labeling in the medial pallium, the presumptive hippocampal homologue, while geometry-feature toads were found to have increased neuronal labeling in the medial, dorsal, and lateral pallia. The data indicate medial pallial participation in guiding navigation by environmental geometry and lateral, and to a lesser extent dorsal, pallial participation in guiding navigation by a prominent visual feature. As such, participation of the medial pallium/hippocampus in spatial cognition appears to be a conserved feature of terrestrial vertebrates even if their life history is still tied to water, a brain-behavior feature seemingly at least as ancient as the evolutionary transition to life on land.

  7. Do Humans Integrate Routes Into a Cognitive Map? Map- Versus Landmark-Based Navigation of Novel Shortcuts

    ERIC Educational Resources Information Center

    Foo, Patrick; Warren, William H.; Duchon, Andrew; Tarr, Michael J.

    2005-01-01

    Do humans integrate experience on specific routes into metric survey knowledge of the environment, or do they depend on a simpler strategy of landmark navigation? The authors tested this question using a novel shortcut paradigm during walking in a virtual environment. The authors find that participants could not take successful shortcuts in a…

  8. Do Humans Integrate Routes Into a Cognitive Map? Map- Versus Landmark-Based Navigation of Novel Shortcuts

    ERIC Educational Resources Information Center

    Foo, Patrick; Warren, William H.; Duchon, Andrew; Tarr, Michael J.

    2005-01-01

    Do humans integrate experience on specific routes into metric survey knowledge of the environment, or do they depend on a simpler strategy of landmark navigation? The authors tested this question using a novel shortcut paradigm during walking in a virtual environment. The authors find that participants could not take successful shortcuts in a…

  9. Context-dependent spatially periodic activity in the human entorhinal cortex.

    PubMed

    Nadasdy, Zoltan; Nguyen, T Peter; Török, Ágoston; Shen, Jason Y; Briggs, Deborah E; Modur, Pradeep N; Buchanan, Robert J

    2017-04-10

    The spatially periodic activity of grid cells in the entorhinal cortex (EC) of the rodent, primate, and human provides a coordinate system that, together with the hippocampus, informs an individual of its location relative to the environment and encodes the memory of that location. Among the most defining features of grid-cell activity are the 60° rotational symmetry of grids and preservation of grid scale across environments. Grid cells, however, do display a limited degree of adaptation to environments. It remains unclear if this level of environment invariance generalizes to human grid-cell analogs, where the relative contribution of visual input to the multimodal sensory input of the EC is significantly larger than in rodents. Patients diagnosed with nontractable epilepsy who were implanted with entorhinal cortical electrodes performing virtual navigation tasks to memorized locations enabled us to investigate associations between grid-like patterns and environment. Here, we report that the activity of human entorhinal cortical neurons exhibits adaptive scaling in grid period, grid orientation, and rotational symmetry in close association with changes in environment size, shape, and visual cues, suggesting scale invariance of the frequency, rather than the wavelength, of spatially periodic activity. Our results demonstrate that neurons in the human EC represent space with an enhanced flexibility relative to neurons in rodents because they are endowed with adaptive scalability and context dependency.

  10. Context-dependent spatially periodic activity in the human entorhinal cortex

    PubMed Central

    Nguyen, T. Peter; Török, Ágoston; Shen, Jason Y.; Briggs, Deborah E.; Modur, Pradeep N.; Buchanan, Robert J.

    2017-01-01

    The spatially periodic activity of grid cells in the entorhinal cortex (EC) of the rodent, primate, and human provides a coordinate system that, together with the hippocampus, informs an individual of its location relative to the environment and encodes the memory of that location. Among the most defining features of grid-cell activity are the 60° rotational symmetry of grids and preservation of grid scale across environments. Grid cells, however, do display a limited degree of adaptation to environments. It remains unclear if this level of environment invariance generalizes to human grid-cell analogs, where the relative contribution of visual input to the multimodal sensory input of the EC is significantly larger than in rodents. Patients diagnosed with nontractable epilepsy who were implanted with entorhinal cortical electrodes performing virtual navigation tasks to memorized locations enabled us to investigate associations between grid-like patterns and environment. Here, we report that the activity of human entorhinal cortical neurons exhibits adaptive scaling in grid period, grid orientation, and rotational symmetry in close association with changes in environment size, shape, and visual cues, suggesting scale invariance of the frequency, rather than the wavelength, of spatially periodic activity. Our results demonstrate that neurons in the human EC represent space with an enhanced flexibility relative to neurons in rodents because they are endowed with adaptive scalability and context dependency. PMID:28396399

  11. Coexistence between wildlife and humans at fine spatial scales

    PubMed Central

    Carter, Neil H.; Shrestha, Binoj K.; Karki, Jhamak B.; Pradhan, Narendra Man Babu; Liu, Jianguo

    2012-01-01

    Many wildlife species face imminent extinction because of human impacts, and therefore, a prevailing belief is that some wildlife species, particularly large carnivores and ungulates, cannot coexist with people at fine spatial scales (i.e., cannot regularly use the exact same point locations). This belief provides rationale for various conservation programs, such as resettling human communities outside protected areas. However, quantitative information on the capacity and mechanisms for wildlife to coexist with humans at fine spatial scales is scarce. Such information is vital, because the world is becoming increasingly crowded. Here, we provide empirical information about the capacity and mechanisms for tigers (a globally endangered species) to coexist with humans at fine spatial scales inside and outside Nepal’s Chitwan National Park, a flagship protected area for imperiled wildlife. Information obtained from field cameras in 2010 and 2011 indicated that human presence (i.e., people on foot and vehicles) was ubiquitous and abundant throughout the study site; however, tiger density was also high. Surprisingly, even at a fine spatial scale (i.e., camera locations), tigers spatially overlapped with people on foot and vehicles in both years. However, in both years, tigers offset their temporal activity patterns to be much less active during the day when human activity peaked. In addition to temporal displacement, tiger–human coexistence was likely enhanced by abundant tiger prey and low levels of tiger poaching. Incorporating fine-scale spatial and temporal activity patterns into conservation plans can help address a major global challenge—meeting human needs while sustaining wildlife. PMID:22949642

  12. Coexistence between wildlife and humans at fine spatial scales.

    PubMed

    Carter, Neil H; Shrestha, Binoj K; Karki, Jhamak B; Pradhan, Narendra Man Babu; Liu, Jianguo

    2012-09-18

    Many wildlife species face imminent extinction because of human impacts, and therefore, a prevailing belief is that some wildlife species, particularly large carnivores and ungulates, cannot coexist with people at fine spatial scales (i.e., cannot regularly use the exact same point locations). This belief provides rationale for various conservation programs, such as resettling human communities outside protected areas. However, quantitative information on the capacity and mechanisms for wildlife to coexist with humans at fine spatial scales is scarce. Such information is vital, because the world is becoming increasingly crowded. Here, we provide empirical information about the capacity and mechanisms for tigers (a globally endangered species) to coexist with humans at fine spatial scales inside and outside Nepal's Chitwan National Park, a flagship protected area for imperiled wildlife. Information obtained from field cameras in 2010 and 2011 indicated that human presence (i.e., people on foot and vehicles) was ubiquitous and abundant throughout the study site; however, tiger density was also high. Surprisingly, even at a fine spatial scale (i.e., camera locations), tigers spatially overlapped with people on foot and vehicles in both years. However, in both years, tigers offset their temporal activity patterns to be much less active during the day when human activity peaked. In addition to temporal displacement, tiger-human coexistence was likely enhanced by abundant tiger prey and low levels of tiger poaching. Incorporating fine-scale spatial and temporal activity patterns into conservation plans can help address a major global challenge-meeting human needs while sustaining wildlife.

  13. HUMAN ENGINEERING FOR AN EFFECTIVE AIR-NAVIGATION AND TRAFFIC-CONTROL SYSTEM, AND APPENDIXES 1 THRU 3

    DTIC Science & Technology

    1951-03-14

    Henneman F. C.Frnick W. E. Kappauf WA R. Garner E. B. Newman F. C . Frick A. C . Williams, Jr.SW. R. Garner j.• JW. Gebhord W. F. Grether A report...Psychology Washington, D. C . UNCLASSIFIED ATI 133 954 (COPIES OSTAIMAULE FROM ASTIA-OSC) OHIO STATE UNIVERSITY RESECNH FOUNDATION, COLmUS HUMAN...Air Navigation Development Board, A-9 Civil Aeronautics Administration Washington 25, D. C . Dear Dr. Ewing: The attached report, entitled Human

  14. Multiple spatial frequency channels in human visual perceptual memory.

    PubMed

    Nemes, V A; Whitaker, D; Heron, J; McKeefry, D J

    2011-12-08

    Current models of short-term visual perceptual memory invoke mechanisms that are closely allied to low-level perceptual discrimination mechanisms. The purpose of this study was to investigate the extent to which human visual perceptual memory for spatial frequency is based upon multiple, spatially tuned channels similar to those found in the earliest stages of visual processing. To this end we measured how performance on a delayed spatial frequency discrimination paradigm was affected by the introduction of interfering or 'memory masking' stimuli of variable spatial frequency during the delay period. Masking stimuli were shown to induce shifts in the points of subjective equality (PSE) when their spatial frequencies were within a bandwidth of 1.2 octaves of the reference spatial frequency. When mask spatial frequencies differed by more than this value, there was no change in the PSE from baseline levels. This selective pattern of masking was observed for different spatial frequencies and demonstrates the existence of multiple, spatially tuned mechanisms in visual perceptual memory. Memory masking effects were also found to occur for horizontal separations of up to 6 deg between the masking and test stimuli and lacked any orientation selectivity. These findings add further support to the view that low-level sensory processing mechanisms form the basis for the retention of spatial frequency information in perceptual memory. However, the broad range of transfer of memory masking effects across spatial location and other dimensions indicates more long range, long duration interactions between spatial frequency channels that are likely to rely contributions from neural processes located in higher visual areas.

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

    PubMed

    Lee, Choong-Hee; Ryu, Jungwon; Lee, Sang-Hun; Kim, Hakjin; Lee, Inah

    2016-08-01

    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.

  16. 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

  17. Role of human moving on city spatial evolution

    NASA Astrophysics Data System (ADS)

    Zhao, F. X.; Wu, J. J.; Sun, H. J.; Gao, Z. Y.

    2015-02-01

    Human migration plays an important role in the city spatial evolution. This paper presents a new simulation model of city spatial evolution that explicitly considers preference and exploration in the migration choice decision process. In the model, the preference means that human prefer to move to the communities which have more people, while the exploration implies that human wish to explore the unknown communities randomly. By introducing the carrying capacity (CC), maximum movement distance (MMD), migration rate (MR) and random migration parameter (RMP), we investigate the effects of them on the city spatial distribution. All of the parameters can govern how many people can live in each community, how far people can explore and how many people move per time step, etc. A numerical simulation experiment is presented to illustrate that the form of the city is centralized with the increase of CC, MMD and MR, while it will be decentralized as the RMP grows.

  18. 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.

  19. Effects of developmental exposure to bisphenol A and ethinyl estradiol on spatial navigational learning and memory in painted turtles (Chrysemys picta).

    PubMed

    Manshack, Lindsey K; Conard, Caroline M; Johnson, Sarah A; Alex, Jorden M; Bryan, Sara J; Deem, Sharon L; Holliday, Dawn K; Ellersieck, Mark R; Rosenfeld, Cheryl S

    2016-09-01

    Developmental exposure of turtles and other reptiles to endocrine disrupting chemicals (EDCs), including bisphenol A (BPA) and ethinyl estradiol (EE2, estrogen present in birth control pills), can induce partial to full gonadal sex-reversal in males. No prior studies have considered whether in ovo exposure to EDCs disrupts normal brain sexual differentiation. Yet, rodent model studies indicate early exposure to these chemicals disturbs sexually selected behavioral traits, including spatial navigational learning and memory. Thus, we sought to determine whether developmental exposure of painted turtles (Chrysemys picta) to BPA and EE2 results in sex-dependent behavioral changes. At developmental stage 17, turtles incubated at 26⁰C (male-inducing temperature) were treated with 1) BPA High (100μg /mL), 2) BPA Low (0.01μg/mL), 3) EE2 (0.2μg/mL), or 4) vehicle or no vehicle control groups. Five months after hatching, turtles were tested with a spatial navigational test that included four food containers, only one of which was baited with food. Each turtle was randomly assigned one container that did not change over the trial period. Each individual was tested for 14 consecutive days. Results show developmental exposure to BPA High and EE2 improved spatial navigational learning and memory, as evidenced by increased number of times spent in the correct target zone and greater likelihood of solving the maze compared to control turtles. This study is the first to show that in addition to overriding temperature sex determination (TSD) of the male gonad, these EDCs may induce sex-dependent behavioral changes in turtles. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. The Effects of Spatial Visualization Ability and Graphical Navigational Aids on Cognitive Load and Learning from Web-Based Instruction

    ERIC Educational Resources Information Center

    Morozov, Andrew

    2009-01-01

    This study contributes to research investigating the effects of individual differences and online instructional design on learning. Learning performance was compared across three hypertext formats incorporating different navigational aids. The hierarchical map represented the physical structure of the hypertext in one condition, while the network…

  1. Planning of spatially-oriented locomotion following focal brain damage in humans: A pilot study.

    PubMed

    Hicheur, Halim; Boujon, Carole; Wong, Cuebong; Pham, Quang-Cuong; Annoni, Jean-Marie; Bihl, Titus

    2016-03-15

    Motor impairments in human gait following stroke or focal brain damage are well documented. Here, we investigated whether stroke and/or focal brain damage also affect the navigational component of spatially oriented locomotion. Ten healthy adult participants and ten adult brain-damaged patients had to walk towards distant targets from different starting positions (with vision or blindfolded). No instructions as to which the path to follow were provided to them. We observed very similar geometrical forms of paths across the two groups of participants and across visual conditions. This spatial stereotypy of whole-body displacements was observed following brain damage, even in the most severely impaired (hemiparetic) patients. This contrasted with much more variability at the temporal level. In particular, healthy participants and non-hemiparetic patients varied their walking speed according to curvature changes along the path. On the contrary, the walking speed profiles were not stereotypical and were not systematically constrained by path geometry in hemiparetic patients where it was associated with different stepping behaviors. These observations confirm the dissociation between cognitive and motor aspects of gait recovery post-stroke. The impact of these findings on the understanding of the functional and anatomical organization of spatially-oriented locomotion and for rehabilitation purposes is discussed and contextualized in the light of recent advances in electrophysiological studies.

  2. 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.

  3. Lunar optical wireless communication and navigation network for robotic and human exploration

    NASA Astrophysics Data System (ADS)

    Arnon, Shlomi

    2011-09-01

    Exploration of the moon is a stepping stone for further research of our solar system, the galaxy and, ultimately, the universe. Many intriguing questions arise regarding the moon; what is the moon's composition and structure, what is the potential for settlement or colonization and how did our solar system evolve to name a few. New technologies are required in order to answer these questions. The main goal in our project is to develop technologies for optical wireless communication and navigation systems for use in robotic and in human exploration on the moon. These technologies facilitate the exploration of the moon surface by enabling placing scientific equipment at precise locations and subsequently transferring the acquired information at high data rates. The main advantages of optical technology in comparison with RF technology are: a) high data rate transmission, b) small size and weight of equipment, c) low power consumption, d) very high accuracy in measuring range and orientation and e) no contamination of the quiet electromagnetic (EM) environment on the dark side of the moon In this paper we present a mathematical model and an engineering implementation of a system that simultaneously communicates, and measures the location and orientation of a remote robot on the moon.

  4. Spatial Representation and Reasoning for Human-Robot Collaboration

    DTIC Science & Technology

    2007-07-01

    SENSOR OFF. TARGET APPEARS TO HAVE STRATEGY “ NE -NW- cycle” AND MISSION PATROL. CURRENT PLANS ARE TO HIDE "east-of" "pillar2". REPORTING FROM...Conference on Human-Robot Interactions, Salt lake City, UT, ACM Press: New York. 242-249. Tversky, B. 1993. Cognitive maps, cognitive collages , and spatial

  5. 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

  6. Dissociated deficits of visuo-spatial memory in near space and navigational space: evidence from brain-damaged patients and healthy older participants.

    PubMed

    Piccardi, L; Iaria, G; Bianchini, F; Zompanti, L; Guariglia, C

    2011-05-01

    Defects confined to spatial memory can severely affect a variety of daily life activities, such as remembering the location of objects or navigating the environment, until now the skills involved have been mostly assessed with regard to the visual domain using traditional pencil and paper tests. Our aim was to test the efficacy of a recently developed psychometric instrument (Walking Corsi Test: WalCT) to assess the specific contribution of spatial memory to the complex task of retrieving route knowledge. The WalCT is a 3 × 2.5-m version of the well-known Corsi Block-tapping Test (CBT), in which patients are required to memorize (and replicate) a sequence of body displacements. We assessed the ability of left and right brain-damaged patients, as well as healthy young and senior controls, to perform both the CBT and the WalCT. Results showed differences related to age in the healthy individuals and specific functional dissociations in the brain-damaged patients. The double dissociations found in this study demonstrate the importance of having a task able to detect navigational disorders, because virtual reality tasks are often much too difficult for aged brain-damaged patients to perform.

  7. Strategies for navigating large areas: a GIS spatial ecology analysis of the bearded saki monkey, Chiropotes sagulatus, in Suriname.

    PubMed

    Gregory, Tremaine; Mullett, Amanda; Norconk, Marilyn A

    2014-06-01

    Animals with long day paths and large home ranges expend a considerable amount of energy on travel. Studies have shown that in the interest of reducing energy expenditure, animals selectively navigate the landscape using a variety of strategies. However, these studies have generally focused on terrestrial animals. Here we present data on an exceedingly mobile arboreal animal, bearded saki monkeys, in a topographically variable landscape in Suriname. Using ArcMap and Google Earth, we explore two potential navigation strategies: the nonrandom use of travel areas and the use of ridges in slope navigation. Over a year of data collection, bearded sakis were found to use relatively long travel paths daily, use some areas more intensely than others for travel, and when travel paths were converted to strings of points, 40.3% and 63.9% of the points were located on (50 m from the main ridgeline) or near (100 m from the main ridgeline) ridge tops, respectively. Thus in a habitat of high relief we found support for intensive use of ridge tops or slopes close to ridge tops by bearded sakis. Selective habitat use may be related to surveying tree crowns for fruit by large, fast moving groups of bearded sakis or monitoring the presence of potential predators.

  8. Finding the way: a critical discussion of anthropological theories of human spatial orientation with reference to reindeer herders of northeastern Europe and western Siberia.

    PubMed

    Istomin, Kirill V; Dwyer, Mark J

    2009-02-01

    In anthropology, research on human spatial orientation (wayfinding) has centered on two conflicting theories: the "mental map," whereby humans build abstract cognitive representations of the spatial relations between objects, and "practical mastery," which rejects the idea that such abstract representations exist and, in its most developed form, suggests that wayfinding is a process of moving from one recognized visual perspective (vista) to another (transitions between vistas). In this paper we reveal, on the basis of existing psychology and geography research, that both wayfinding theories are in fact complementary: humans rely on mental maps but also memorize vistas while navigating, and an individual's navigation method, ability, and the form of the mental map is likely to depend on a situation as well as on factors such as age, sex, familiarity with the environment, and life history. We demonstrate (using research material obtained during fieldwork carried out among Komi and Nenets reindeer herders) that anthropology can contribute to human spatial cognitive research, which has traditionally been an interdisciplinary endeavor, by identifying differences in spatial representation between different people and peoples. However, future contributions can be achieved only if anthropologists accept that mental maps and route knowledge (as advocated by practical mastery) are part and parcel of spatial cognition.

  9. The Effects of Terrain and Navigation on Human Extravehicular Activity Walkback Performance on the Moon

    NASA Technical Reports Server (NTRS)

    Norcross, Jason; Stroud, Leah C.; Schaffner, Grant; Glass, Brian J.; Lee, Pascal C.; Jones, Jeff A.; Gernhardt, Michael L.

    2008-01-01

    Results of the EVA Walkback Test showed that 6 male astronauts were able to ambulate 10 km on a level treadmill while wearing a prototype EVA suit in simulated lunar gravity. However, the effects of lunar terrain, topography, and real-time navigation on ambulation performance are unknown. Primary objective: To characterize the effect of lunar-like terrain and navigation on VO2 and distance traveled during an unsuited 10 km (straight-line distance) ambulatory return in earth gravity.

  10. Natural auditory scene statistics shapes human spatial hearing.

    PubMed

    Parise, Cesare V; Knorre, Katharina; Ernst, Marc O

    2014-04-22

    Human perception, cognition, and action are laced with seemingly arbitrary mappings. In particular, sound has a strong spatial connotation: Sounds are high and low, melodies rise and fall, and pitch systematically biases perceived sound elevation. The origins of such mappings are unknown. Are they the result of physiological constraints, do they reflect natural environmental statistics, or are they truly arbitrary? We recorded natural sounds from the environment, analyzed the elevation-dependent filtering of the outer ear, and measured frequency-dependent biases in human sound localization. We find that auditory scene statistics reveals a clear mapping between frequency and elevation. Perhaps more interestingly, this natural statistical mapping is tightly mirrored in both ear-filtering properties and in perceived sound location. This suggests that both sound localization behavior and ear anatomy are fine-tuned to the statistics of natural auditory scenes, likely providing the basis for the spatial connotation of human hearing.

  11. Natural auditory scene statistics shapes human spatial hearing

    PubMed Central

    Parise, Cesare V.; Knorre, Katharina; Ernst, Marc O.

    2014-01-01

    Human perception, cognition, and action are laced with seemingly arbitrary mappings. In particular, sound has a strong spatial connotation: Sounds are high and low, melodies rise and fall, and pitch systematically biases perceived sound elevation. The origins of such mappings are unknown. Are they the result of physiological constraints, do they reflect natural environmental statistics, or are they truly arbitrary? We recorded natural sounds from the environment, analyzed the elevation-dependent filtering of the outer ear, and measured frequency-dependent biases in human sound localization. We find that auditory scene statistics reveals a clear mapping between frequency and elevation. Perhaps more interestingly, this natural statistical mapping is tightly mirrored in both ear-filtering properties and in perceived sound location. This suggests that both sound localization behavior and ear anatomy are fine-tuned to the statistics of natural auditory scenes, likely providing the basis for the spatial connotation of human hearing. PMID:24711409

  12. Attention reduces spatial uncertainty in human ventral temporal cortex.

    PubMed

    Kay, Kendrick N; Weiner, Kevin S; Grill-Spector, Kalanit

    2015-03-02

    Ventral temporal cortex (VTC) is the latest stage of the ventral "what" visual pathway, which is thought to code the identity of a stimulus regardless of its position or size [1, 2]. Surprisingly, recent studies show that position information can be decoded from VTC [3-5]. However, the computational mechanisms by which spatial information is encoded in VTC are unknown. Furthermore, how attention influences spatial representations in human VTC is also unknown because the effect of attention on spatial representations has only been examined in the dorsal "where" visual pathway [6-10]. Here, we fill these significant gaps in knowledge using an approach that combines functional magnetic resonance imaging and sophisticated computational methods. We first develop a population receptive field (pRF) model [11, 12] of spatial responses in human VTC. Consisting of spatial summation followed by a compressive nonlinearity, this model accurately predicts responses of individual voxels to stimuli at any position and size, explains how spatial information is encoded, and reveals a functional hierarchy in VTC. We then manipulate attention and use our model to decipher the effects of attention. We find that attention to the stimulus systematically and selectively modulates responses in VTC, but not early visual areas. Locally, attention increases eccentricity, size, and gain of individual pRFs, thereby increasing position tolerance. However, globally, these effects reduce uncertainty regarding stimulus location and actually increase position sensitivity of distributed responses across VTC. These results demonstrate that attention actively shapes and enhances spatial representations in the ventral visual pathway.

  13. Characterizing optical properties and spatial heterogeneity of human ovarian tissue using spatial frequency domain imaging

    NASA Astrophysics Data System (ADS)

    Nandy, Sreyankar; Mostafa, Atahar; Kumavor, Patrick D.; Sanders, Melinda; Brewer, Molly; Zhu, Quing

    2016-10-01

    A spatial frequency domain imaging (SFDI) system was developed for characterizing ex vivo human ovarian tissue using wide-field absorption and scattering properties and their spatial heterogeneities. Based on the observed differences between absorption and scattering images of different ovarian tissue groups, six parameters were quantitatively extracted. These are the mean absorption and scattering, spatial heterogeneities of both absorption and scattering maps measured by a standard deviation, and a fitting error of a Gaussian model fitted to normalized mean Radon transform of the absorption and scattering maps. A logistic regression model was used for classification of malignant and normal ovarian tissues. A sensitivity of 95%, specificity of 100%, and area under the curve of 0.98 were obtained using six parameters extracted from the SFDI images. The preliminary results demonstrate the diagnostic potential of the SFDI method for quantitative characterization of wide-field optical properties and the spatial distribution heterogeneity of human ovarian tissue. SFDI could be an extremely robust and valuable tool for evaluation of the ovary and detection of neoplastic changes of ovarian cancer.

  14. Characterizing optical properties and spatial heterogeneity of human ovarian tissue using spatial frequency domain imaging

    PubMed Central

    Nandy, Sreyankar; Mostafa, Atahar; Kumavor, Patrick D; Sanders, Melinda; Brewer, Molly; Zhu, Quing

    2016-01-01

    Abstract. A spatial frequency domain imaging (SFDI) system was developed for characterizing ex vivo human ovarian tissue using wide-field absorption and scattering properties and their spatial heterogeneities. Based on the observed differences between absorption and scattering images of different ovarian tissue groups, six parameters were quantitatively extracted. These are the mean absorption and scattering, spatial heterogeneities of both absorption and scattering maps measured by a standard deviation, and a fitting error of a Gaussian model fitted to normalized mean Radon transform of the absorption and scattering maps. A logistic regression model was used for classification of malignant and normal ovarian tissues. A sensitivity of 95%, specificity of 100%, and area under the curve of 0.98 were obtained using six parameters extracted from the SFDI images. The preliminary results demonstrate the diagnostic potential of the SFDI method for quantitative characterization of wide-field optical properties and the spatial distribution heterogeneity of human ovarian tissue. SFDI could be an extremely robust and valuable tool for evaluation of the ovary and detection of neoplastic changes of ovarian cancer. PMID:26822943

  15. Predictability in orbital reconstruction: A human cadaver study. Part II: Navigation-assisted orbital reconstruction.

    PubMed

    Dubois, Leander; Schreurs, Ruud; Jansen, Jesper; Maal, Thomas J J; Essig, Harald; Gooris, Peter J J; Becking, Alfred G

    2015-12-01

    Preformed orbital reconstruction plates are useful for treating orbital defects. However, intraoperative errors can lead to misplaced implants and poor outcomes. Navigation-assisted surgery may help optimize orbital reconstruction. We aimed to explore whether navigation-assisted surgery is more predictable than traditional orbital reconstruction for optimal implant placement. Pre-injury computed tomography scans were obtained for 10 cadaver heads (20 orbits). Complex orbital fractures (Class III-IV) were created in all orbits, which were reconstructed using a transconjunctival approach with and without navigation. The best possible fit of the stereolithographic file of a preformed orbital mesh plate was used as the optimal position for reconstruction. The accuracy of the implant positions was evaluated using iPlan software. The consistency of orbital reconstruction was lower in the traditional reconstructions than in the navigation group in the parameters of translation and rotation. Implant position also differed significantly in the parameters of translation (p = 0.002) and rotation (pitch: p = 0.77; yaw: p < 0.001; roll: p = 0.001). Compared with traditional orbital reconstruction, navigation-assisted reconstruction provides more predictable anatomical reconstruction of complex orbital defects and significantly improves orbital implant position.

  16. Developing Spatial Orientation and Spatial Memory with a Treasure Hunting Game

    ERIC Educational Resources Information Center

    Lin, Chien-Heng; Chen, Chien-Min; Lou, Yu-Chiung

    2014-01-01

    The abilities of both spatial orientation and spatial memory play very important roles in human navigation and spatial cognition. Since such abilities are difficult to strengthen through books or classroom instruction, there are no particular curricula or methods to assist in their development. Therefore, this study develops a spatial…

  17. Developing Spatial Orientation and Spatial Memory with a Treasure Hunting Game

    ERIC Educational Resources Information Center

    Lin, Chien-Heng; Chen, Chien-Min; Lou, Yu-Chiung

    2014-01-01

    The abilities of both spatial orientation and spatial memory play very important roles in human navigation and spatial cognition. Since such abilities are difficult to strengthen through books or classroom instruction, there are no particular curricula or methods to assist in their development. Therefore, this study develops a spatial…

  18. Human seizures couple across spatial scales through travelling wave dynamics.

    PubMed

    Martinet, L-E; Fiddyment, G; Madsen, J R; Eskandar, E N; Truccolo, W; Eden, U T; Cash, S S; Kramer, M A

    2017-04-04

    Epilepsy-the propensity toward recurrent, unprovoked seizures-is a devastating disease affecting 65 million people worldwide. Understanding and treating this disease remains a challenge, as seizures manifest through mechanisms and features that span spatial and temporal scales. Here we address this challenge through the analysis and modelling of human brain voltage activity recorded simultaneously across microscopic and macroscopic spatial scales. We show that during seizure large-scale neural populations spanning centimetres of cortex coordinate with small neural groups spanning cortical columns, and provide evidence that rapidly propagating waves of activity underlie this increased inter-scale coupling. We develop a corresponding computational model to propose specific mechanisms-namely, the effects of an increased extracellular potassium concentration diffusing in space-that support the observed spatiotemporal dynamics. Understanding the multi-scale, spatiotemporal dynamics of human seizures-and connecting these dynamics to specific biological mechanisms-promises new insights to treat this devastating disease.

  19. Human seizures couple across spatial scales through travelling wave dynamics

    PubMed Central

    Martinet, L-E; Fiddyment, G.; Madsen, J. R.; Eskandar, E. N.; Truccolo, W.; Eden, U. T.; Cash, S. S.; Kramer, M. A.

    2017-01-01

    Epilepsy—the propensity toward recurrent, unprovoked seizures—is a devastating disease affecting 65 million people worldwide. Understanding and treating this disease remains a challenge, as seizures manifest through mechanisms and features that span spatial and temporal scales. Here we address this challenge through the analysis and modelling of human brain voltage activity recorded simultaneously across microscopic and macroscopic spatial scales. We show that during seizure large-scale neural populations spanning centimetres of cortex coordinate with small neural groups spanning cortical columns, and provide evidence that rapidly propagating waves of activity underlie this increased inter-scale coupling. We develop a corresponding computational model to propose specific mechanisms—namely, the effects of an increased extracellular potassium concentration diffusing in space—that support the observed spatiotemporal dynamics. Understanding the multi-scale, spatiotemporal dynamics of human seizures—and connecting these dynamics to specific biological mechanisms—promises new insights to treat this devastating disease. PMID:28374740

  20. Spatial augmented reality based high accuracy human face projection

    NASA Astrophysics Data System (ADS)

    Li, Dong; Xie, Jinghui; Li, Yufeng; Weng, Dongdong; Liu, Yue

    2015-08-01

    This paper discusses the imaging principles and the technical difficulties of spatial augmented reality based human face projection. A novel geometry correction method is proposed to realize fast, high-accuracy face model projection. Using a depth camera to reconstruct the projected object, the relative position from the rendered model to the projector can be accessed and the initial projection image is generated. Then the projected image is distorted by using Bezier interpolation to guarantee that the projected texture matches with the object surface. The proposed method is under a simple process flow and can achieve high perception registration of virtual and real object. In addition, this method has a good performance in the condition that the reconstructed model is not exactly same with the rendered virtual model which extends its application area in the spatial augmented reality based human face projection.

  1. Human seizures couple across spatial scales through travelling wave dynamics

    NASA Astrophysics Data System (ADS)

    Martinet, L.-E.; Fiddyment, G.; Madsen, J. R.; Eskandar, E. N.; Truccolo, W.; Eden, U. T.; Cash, S. S.; Kramer, M. A.

    2017-04-01

    Epilepsy--the propensity toward recurrent, unprovoked seizures--is a devastating disease affecting 65 million people worldwide. Understanding and treating this disease remains a challenge, as seizures manifest through mechanisms and features that span spatial and temporal scales. Here we address this challenge through the analysis and modelling of human brain voltage activity recorded simultaneously across microscopic and macroscopic spatial scales. We show that during seizure large-scale neural populations spanning centimetres of cortex coordinate with small neural groups spanning cortical columns, and provide evidence that rapidly propagating waves of activity underlie this increased inter-scale coupling. We develop a corresponding computational model to propose specific mechanisms--namely, the effects of an increased extracellular potassium concentration diffusing in space--that support the observed spatiotemporal dynamics. Understanding the multi-scale, spatiotemporal dynamics of human seizures--and connecting these dynamics to specific biological mechanisms--promises new insights to treat this devastating disease.

  2. Toward critical spatial thinking in the social sciences and humanities

    PubMed Central

    Goodchild, Michael F.; Janelle, Donald G.

    2010-01-01

    The integration of geographically referenced information into the conceptual frameworks and applied uses of the social sciences and humanities has been an ongoing process over the past few centuries. It has gained momentum in recent decades with advances in technologies for computation and visualization and with the arrival of new data sources. This article begins with an overview of this transition, and argues that the spatial integration of information resources and the cross-disciplinary sharing of analysis and representation methodologies are important forces for the integration of scientific and artistic expression, and that they draw on core concepts in spatial (and spatio-temporal) thinking. We do not suggest that this is akin to prior concepts of unified knowledge systems, but we do maintain that the boundaries to knowledge transfer are disintegrating and that our abilities in problem solving for purposes of artistic expression and scientific development are enhanced through spatial perspectives. Moreover, approaches to education at all levels must recognize the need to impart proficiency in the critical and efficient application of these fundamental spatial concepts, if students and researchers are to make use of expanding access to a broadening range of spatialized information and data processing technologies. PMID:20454588

  3. 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

  4. Implementation of a socio-ecological system navigation approach to human development in sub-saharan african communities.

    PubMed

    Gilioli, Gianni; Caroli, Anna Maria; Tikubet, Getachew; Herren, Hans R; Baumgärtner, Johann

    2014-03-26

    This paper presents a framework for the development of socio-ecological systems towards enhanced sustainability. Emphasis is given to the dynamic properties of complex, adaptive social-ecological systems, their structure and to the fundamental role of agriculture. The tangible components that meet the needs of specific projects executed in Kenya and Ethiopia encompass project objectives, innovation, facilitation, continuous recording and analyses of monitoring data, that allow adaptive management and system navigation. Two case studies deal with system navigation through the mitigation of key constraints; they aim to improve human health thanks to anopheline malaria vectors control in Nyabondo (Kenya), and to improve cattle health through tsetse control and antitrypanosomal drug administration to cattle in Luke (Ethiopia). The second case deals with a socio-ecological navigation system to enhance sustainability, establishing a periurban diversified enterprise in Addis Ababa (Ethiopia) and developing a rural sustainable social-ecological system in Luke (Ethiopia). The project procedures are briefly described here and their outcomes are analysed in relation to the stated objectives. The methodology for human and cattle disease vector control were easier to implement than the navigation of social-ecological systems towards sustainability enhancement. The achievements considerably differed between key constraints removal and sustainability enhancement projects. Some recommendations are made to rationalise human and cattle health improvement efforts and to smoothen the road towards enhanced sustainability: i) technology system implementation should be carried out through an innovation system; ii) transparent monitoring information should be continuously acquired and evaluated for assessing the state of the system in relation to stated objectives for (a) improving the insight into the systems behaviour and (b) rationalizing decision support; iii) the different views of

  5. Implementation of a Socio-Ecological System Navigation Approach to Human Development in Sub-Saharan African Communities

    PubMed Central

    Gilioli, Gianni; Caroli, Anna Maria; Tikubet, Getachew; Herren, Hans R.; Baumgärtner, Johann

    2014-01-01

    This paper presents a framework for the development of socio-ecological systems towards enhanced sustainability. Emphasis is given to the dynamic properties of complex, adaptive social-ecological systems, their structure and to the fundamental role of agriculture. The tangible components that meet the needs of specific projects executed in Kenya and Ethiopia encompass project objectives, innovation, facilitation, continuous recording and analyses of monitoring data, that allow adaptive management and system navigation. Two case studies deal with system navigation through the mitigation of key constraints; they aim to improve human health thanks to anopheline malaria vectors control in Nyabondo (Kenya), and to improve cattle health through tsetse control and antitrypanosomal drug administration to cattle in Luke (Ethiopia). The second case deals with a socio-ecological navigation system to enhance sustainability, establishing a periurban diversified enterprise in Addis Ababa (Ethiopia) and developing a rural sustainable social-ecological system in Luke (Ethiopia). The project procedures are briefly described here and their outcomes are analysed in relation to the stated objectives. The methodology for human and cattle disease vector control were easier to implement than the navigation of social-ecological systems towards sustainability enhancement. The achievements considerably differed between key constraints removal and sustainability enhancement projects. Some recommendations are made to rationalise human and cattle health improvement efforts and to smoothen the road towards enhanced sustainability: i) technology system implementation should be carried out through an innovation system; ii) transparent monitoring information should be continuously acquired and evaluated for assessing the state of the system in relation to stated objectives for (a) improving the insight into the systems behaviour and (b) rationalizing decision support; iii) the different views of

  6. The Temporal Context Model in spatial navigation and relational learning: Toward a common explanation of medial temporal lobe function across domains

    PubMed Central

    Howard, Marc W.; Fotedar, Mrigankka S.; Datey, Aditya V.; Hasselmo, Michael E.

    2005-01-01

    The medial temporal lobe (MTL) has been studied extensively at all levels of analysis, yet its function remains unclear. Theory regarding the cognitive function of the MTL has centered along 3 themes. Different authors have emphasized the role of the MTL in episodic recall, spatial navigation, or relational memory. Starting with the temporal context model (M. W. Howard and M. J. Kahana, 2002), a distributed memory model that has been applied to benchmark data from episodic recall tasks, the authors propose that the entorhinal cortex supports a gradually changing representation of temporal context and the hippocampus proper enables retrieval of these contextual states. Simulation studies show this hypothesis explains the firing of place cells in the entorhinal cortex and the behavioral effects of hippocampal lesion in relational memory tasks. These results constitute a first step towards a unified computational theory of MTL function that integrates neurophysiological, neuropsychological and cognitive findings. PMID:15631589

  7. The effects of combined lesions of the subicular complex and the entorhinal cortex on two forms of spatial navigation in the water maze.

    PubMed

    Oswald, C J; Good, M

    2000-02-01

    The role of the subicular complex and entorhinal cortex (SUB-EC) in spatial learning was examined in 2 water maze experiments. In Experiment 1, rats had to locate a hidden platform that was always a fixed distance and direction from an intramaze landmark. Each day, the landmark and platform were moved to a new location. Both control and SUB-EC-lesioned rats learned to locate the platform equally readily during training. However, the control group was impaired in locating the platform when the visual extramaze cues were concealed, whereas the lesioned group was unaffected by this manipulation. In Experiment 2, the lesioned rats were impaired in finding a hidden platform that was in a fixed place in the water maze and showed no evidence of having learned its location in a probe test. These results suggest that damage to the SUB-EC impairs the integration of geometric information but spares a more general navigational-directional strategy.

  8. Covert spatial attention is functionally intact in amblyopic human adults

    PubMed Central

    Roberts, Mariel; Cymerman, Rachel; Smith, R. Theodore; Kiorpes, Lynne; Carrasco, Marisa

    2016-01-01

    Certain abnormalities in behavioral performance and neural signaling have been attributed to a deficit of visual attention in amblyopia, a neurodevelopmental disorder characterized by a diverse array of visual deficits following abnormal binocular childhood experience. Critically, most have inferred attention's role in their task without explicitly manipulating and measuring its effects against a baseline condition. Here, we directly investigate whether human amblyopic adults benefit from covert spatial attention—the selective processing of visual information in the absence of eye movements—to the same degree as neurotypical observers. We manipulated both involuntary (Experiment 1) and voluntary (Experiment 2) attention during an orientation discrimination task for which the effects of covert spatial attention have been well established in neurotypical and special populations. In both experiments, attention significantly improved accuracy and decreased reaction times to a similar extent (a) between the eyes of the amblyopic adults and (b) between the amblyopes and their age- and gender-matched controls. Moreover, deployment of voluntary attention away from the target location significantly impaired task performance (Experiment 2). The magnitudes of the involuntary and voluntary attention benefits did not correlate with amblyopic depth or severity. Both groups of observers showed canonical performance fields (better performance along the horizontal than vertical meridian and at the lower than upper vertical meridian) and similar effects of attention across locations. Despite their characteristic low-level vision impairments, covert spatial attention remains functionally intact in human amblyopic adults. PMID:28033433

  9. Covert spatial attention is functionally intact in amblyopic human adults.

    PubMed

    Roberts, Mariel; Cymerman, Rachel; Smith, R Theodore; Kiorpes, Lynne; Carrasco, Marisa

    2016-12-01

    Certain abnormalities in behavioral performance and neural signaling have been attributed to a deficit of visual attention in amblyopia, a neurodevelopmental disorder characterized by a diverse array of visual deficits following abnormal binocular childhood experience. Critically, most have inferred attention's role in their task without explicitly manipulating and measuring its effects against a baseline condition. Here, we directly investigate whether human amblyopic adults benefit from covert spatial attention-the selective processing of visual information in the absence of eye movements-to the same degree as neurotypical observers. We manipulated both involuntary (Experiment 1) and voluntary (Experiment 2) attention during an orientation discrimination task for which the effects of covert spatial attention have been well established in neurotypical and special populations. In both experiments, attention significantly improved accuracy and decreased reaction times to a similar extent (a) between the eyes of the amblyopic adults and (b) between the amblyopes and their age- and gender-matched controls. Moreover, deployment of voluntary attention away from the target location significantly impaired task performance (Experiment 2). The magnitudes of the involuntary and voluntary attention benefits did not correlate with amblyopic depth or severity. Both groups of observers showed canonical performance fields (better performance along the horizontal than vertical meridian and at the lower than upper vertical meridian) and similar effects of attention across locations. Despite their characteristic low-level vision impairments, covert spatial attention remains functionally intact in human amblyopic adults.

  10. Dorsolateral Striatal Lesions Impair Navigation Based on Landmark-Goal Vectors but Facilitate Spatial Learning Based on a "Cognitive Map"

    ERIC Educational Resources Information Center

    Kosaki, Yutaka; Poulter, Steven L.; Austen, Joe M.; McGregor, Anthony

    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…

  11. Dorsolateral Striatal Lesions Impair Navigation Based on Landmark-Goal Vectors but Facilitate Spatial Learning Based on a "Cognitive Map"

    ERIC Educational Resources Information Center

    Kosaki, Yutaka; Poulter, Steven L.; Austen, Joe M.; McGregor, Anthony

    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…

  12. Grid-like Processing of Imagined Navigation

    PubMed Central

    Horner, Aidan J.; Bisby, James A.; Zotow, Ewa; Bush, Daniel; Burgess, Neil

    2016-01-01

    Summary Grid cells in the entorhinal cortex (EC) of rodents [1] and humans [2] fire in a hexagonally distributed spatially periodic manner. In concert with other spatial cells in the medial temporal lobe (MTL) [3, 4, 5, 6], they provide a representation of our location within an environment [7, 8] and are specifically thought to allow the represented location to be updated by self-motion [9]. Grid-like signals have been seen throughout the autobiographical memory system [10], suggesting a much more general role in memory [11, 12]. Grid cells may allow us to move our viewpoint in imagination [13], a useful function for goal-directed navigation and planning [12, 14, 15, 16], and episodic future thinking more generally [17, 18]. We used fMRI to provide evidence for similar grid-like signals in human entorhinal cortex during both virtual navigation and imagined navigation of the same paths. We show that this signal is present in periods of active navigation and imagination, with a similar orientation in both and with the specifically 6-fold rotational symmetry characteristic of grid cell firing. We therefore provide the first evidence suggesting that grid cells are utilized during movement of viewpoint within imagery, potentially underpinning our more general ability to mentally traverse possible routes in the service of planning and episodic future thinking. PMID:26972318

  13. AUTOMATIC NAVIGATION.

    DTIC Science & Technology

    NAVIGATION, REPORTS), (*CONTROL SYSTEMS, *INFORMATION THEORY), ABSTRACTS, OPTIMIZATION, DYNAMIC PROGRAMMING, GAME THEORY, NONLINEAR SYSTEMS, CORRELATION TECHNIQUES, FOURIER ANALYSIS, INTEGRAL TRANSFORMS, DEMODULATION, NAVIGATION CHARTS, PATTERN RECOGNITION, DISTRIBUTION THEORY , TIME SHARING, GRAPHICS, DIGITAL COMPUTERS, FEEDBACK, STABILITY

  14. Human navigation that requires calculating heading vectors recruits parietal cortex in a virtual and visually sparse water maze task in fMRI.

    PubMed

    Rodriguez, Paul F

    2010-08-01

    Spatial navigation in the real-world is a complex task that involves many functions, such as landmark identification, orientation, and the calculation of heading vectors. This study uses a 2 x 2 experimental design with fMRI to isolate mnemonic and navigational processes that accompany the calculation of heading vectors. The conditions are based on a working memory version of the Morris water maze task and navigation takes place in a visually austere virtual environment. In an allocentric condition, subjects navigate around a circular arena where there is one small red square on the wall. Each trial begins with an encoding phase in which subjects locate and navigate to a visible coin. Then, in a test phase, after being randomly repositioned, they retrieve the coin when it is invisible. In a control task, there are eight distinct cues around the arena that provide direct cue-place information. Results show significant interaction effects in bilateral posterior parietal cortex, which is compatible with evidence that parietal cortex helps translating between allocentric coordinates and egocentric directions. There was also greater activation for the allocentric task in right posterior hippocampus and left retrosplenial cortex, which could be related to self-localization and orientation. The findings are also compatible with the recent proposal by Kubie and Fenton (2009) that navigation primarily depends on heading vectors between salient places. 2010 APA, all rights reserved.

  15. Spatial variability of nutrients (N, P) in a deep, temperate lake with a low trophic level supported by global navigation satellite systems, geographic information system and geostatistics.

    PubMed

    Łopata, Michał; Popielarczyk, Dariusz; Templin, Tomasz; Dunalska, Julita; Wiśniewski, Grzegorz; Bigaj, Izabela; Szymański, Daniel

    2014-01-01

    We investigated changes in the spatial distribution of phosphorus (P) and nitrogen (N) in the deep, mesotrophic Lake Hańcza. The raw data collection, supported by global navigation satellite system (GNSS) positioning, was conducted on 79 sampling points. A geostatistical method (kriging) was applied in spatial interpolation. Despite the relatively small area of the lake (3.04 km(2)), compact shape (shore development index of 2.04) and low horizontal exchange of water (retention time 11.4 years), chemical gradients in the surface waters were found. The largest variation concerns the main biogenic element - phosphorus. The average value was 0.032 at the extreme values of 0.019 to 0.265 mg L(-1) (coefficient of variation 87%). Smaller differences are related to nitrogen compounds (0.452-1.424 mg L(-1) with an average value of 0.583 mg L(-1), the coefficient of variation 20%). The parts of the lake which are fed with tributaries are the richest in phosphorus. The water quality of the oligo-mesotrophic Lake Hańcza has been deteriorating in recent years. Our results indicate that inferences about trends in the evolution of examined lake trophic status should be based on an analysis of the data, taking into account the local variation in water chemistry.

  16. Allocentric spatial memory in humans with hippocampal lesions.

    PubMed

    Parslow, David M; Morris, Robin G; Fleminger, Simon; Rahman, Qazi; Abrahams, Sharon; Recce, Michael

    2005-01-01

    An immersive virtual reality (IVR) system was used to investigate allocentric spatial memory in a patient (PR) who had selective hippocampal damage, and also in patients who had undergone unilateral temporal lobectomies (17 right TL and 19 left TL), their performance compared against normal control groups. A human analogue of the Olton [Olton (1979). Hippocampus, space, and memory. Behavioural Brain Science, 2, 315] spatial maze was developed, consisting of a virtual room, a central virtual circular table and an array of radially arranged up-turned 'shells.' The participant had to search these shells in turn in order to find a blue 'cube' that would then 'move' to another location and so on, until all the shells had been target locations. Within-search errors could be made when the participants returned to a previously visited location during a search, and between-search errors when they revisited previously successful, but now incorrect locations. PR made significantly more between-search errors than his control group, but showed no increase in within-search errors. The right TL group showed a similar pattern of impairment, but the left TL group showed no impairment. This finding implicates the right hippocampal formation in spatial memory functioning in a scenario in which the visual environment was controlled so as to eliminate extraneous visual cues.

  17. Spatial localization of electrotactile stimuli on the fingertip in humans.

    PubMed

    Bobich, L R; Warren, J P; Sweeney, J D; Tillery, S I Helms; Santello, M

    2007-12-01

    This study was designed to determine the extent to which sensations elicited by discrete electrotactile stimulation can be spatially localized, with a qualitative comparison to mechanical stimulation, in a 2 x 2 electrode array on the fingertip. Electrotactile stimulation was delivered in two modes: (1) same current to all locations (constant) or (2) current adjusted to perceptual threshold of each location (varied). For each stimulus location, subjects were asked to identify the location of the stimulus. Mechanical stimulation of the same locations on the fingerpad was delivered through von Frey hairs (0.07, 0.2 and 0.4 g). The percentage of accurate responses was computed for all stimulation modes. We found that the accuracy of discrimination of stimulus location in both the constant (46%) and varied (40%) electrotactile stimulation modes was significantly higher than chance level (25%; p < 0.01). Furthermore, subjects were significantly more accurate in discriminating electrotactile stimuli in the constant than in the varied mode (p < 0.05). We also found that the accuracy of spatial discrimination was dependent on stimulation site for mechanical, but not electrotactile stimulation. Finally, we found a significant difference in accuracy over the duration of the experiment only for mechanical modes, which may indicate that electrotactile stimuli are less biased over time. These results suggest that, although low in accuracy, human subjects are able to extract spatial information from electrotactile stimuli. Further research is needed to optimize the amount of the information that can be delivered through electrotactile stimulation.

  18. Spatial distribution of metabolites in the human lens.

    PubMed

    Tamara, Semen O; Yanshole, Lyudmila V; Yanshole, Vadim V; Fursova, Anjella Zh; Stepakov, Denis A; Novoselov, Vladimir P; Tsentalovich, Yuri P

    2016-02-01

    Spatial distribution of 34 metabolites along the optical and equatorial axes of the human lens has been determined. For the majority of metabolites, the homogeneous distribution has been observed. That suggests that the rate of the metabolite transformation in the lens is low due to the general metabolic passivity of the lens fiber cells. However, the redox processes are active in the lens; as a result, some metabolites, including antioxidants, demonstrate the "nucleus-depleted" type of distribution, whereas secondary UV filters show the "nucleus-enriched" type. The metabolite concentrations at the lens poles and equator are similar for all metabolites under study. The concentric pattern of the "nucleus-depleted" and "nucleus-enriched" distributions testifies that the metabolite distribution inside the lens is mostly governed by a passive diffusion, relatively free along the fiber cells and retarded in the radial direction across the cells. No significant difference in the metabolite distribution between the normal and cataractous human lenses was found.

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

    PubMed Central

    Goswami, Nandu; Kavcic, Voyko; Marusic, Uros; Simunic, Bostjan; Rössler, Andreas; Hinghofer-Szalkay, Helmut; Pisot, Rado

    2015-01-01

    We investigated the effects of bed rest (BR) immobilization, with and without computerized cognitive training with virtual spatial navigation task (CCT), on vascular endothelium on older subjects. The effects of 14-day BR immobilization in healthy older males (n=16) of ages 53–65 years on endothelial function were studied using EndoPAT®, a noninvasive and user-independent method. From the group of 16 older men, 8 randomly received CCT during the BR, using virtual navigation tasks in a virtual environment with joystick device. In all the cases, EndoPAT assessments were done at pre- and post-BR immobilization as well as following 28 days of ambulatory recovery. The EndoPAT index increased from 1.53±0.09 (mean ± standard error of the mean) at baseline to 1.61±0.16 following immobilization (P=0.62) in the group with CCT. The EndoPAT index decreased from 2.06±0.13 (mean ± standard error of the mean) at baseline to 1.70±0.09 at the last day of BR study, day 14 (BR14) (P=0.09) in the control group. Additionally, there were no statistically significant differences between BR14 and at 28 days of follow-up (rehabilitation program) (R28). Our results show a trend of immobilization in older persons affecting the vasoconstrictory endothelial response. As the control subjects had a greater increase in EndoPAT index after R28 (+0.018) compared to subjects who had cognitive training (+0.11) (calculated from the first day of BR study), it is possible that cognitive training during BR does not improve endothelial function but rather contributes to slowing down the impairment of endothelial function. Finally, our results also show that EndoPAT may be a useful noninvasive tool to assess the vascular reactivity. PMID:25709419

  20. An assisted navigation training framework based on judgment theory using sparse and discrete human-machine interfaces.

    PubMed

    Lopes, Ana C; Nunes, Urbano

    2009-01-01

    This paper aims to present a new framework to train people with severe motor disabilities steering an assisted mobile robot (AMR), such as a powered wheelchair. Users with high level of motor disabilities are not able to use standard HMIs, which provide a continuous command signal (e. g. standard joystick). For this reason HMIs providing a small set of simple commands, which are sparse and discrete in time must be used (e. g. scanning interface, or brain computer interface), making very difficult to steer the AMR. In this sense, the assisted navigation training framework (ANTF) is designed to train users driving the AMR, in indoor structured environments, using this type of HMIs. Additionally it provides user characterization on steering the robot, which will later be used to adapt the AMR navigation system to human competence steering the AMR. A rule-based lens (RBL) model is used to characterize users on driving the AMR. Individual judgment performance choosing the best manoeuvres is modeled using a genetic-based policy capturing (GBPC) technique characterized to infer non-compensatory judgment strategies from human decision data. Three user models, at three different learning stages, using the RBL paradigm, are presented.

  1. 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.

  2. Spatial Navigation in Complex and Radial Mazes in APP23 Animals and Neurotrophin Signaling as a Biological Marker of Early Impairment

    ERIC Educational Resources Information Center

    Hellweg, Rainer; Huber, Roman; Kuhl, Alexander; Riepe, Matthias W.; Lohmann, Peter

    2006-01-01

    Impairment of hippocampal function precedes frontal and parietal cortex impairment in human Alzheimer's disease(AD). Neurotrophins are critical for behavioral performance and neuronal survival in AD. We used complex and radial mazes to assess spatial orientation and learning in wild-type and B6-Tg(ThylAPP)23Sdz (APP23) animals, a transgenic mouse…

  3. Spatial Navigation in Complex and Radial Mazes in APP23 Animals and Neurotrophin Signaling as a Biological Marker of Early Impairment

    ERIC Educational Resources Information Center

    Hellweg, Rainer; Huber, Roman; Kuhl, Alexander; Riepe, Matthias W.; Lohmann, Peter

    2006-01-01

    Impairment of hippocampal function precedes frontal and parietal cortex impairment in human Alzheimer's disease(AD). Neurotrophins are critical for behavioral performance and neuronal survival in AD. We used complex and radial mazes to assess spatial orientation and learning in wild-type and B6-Tg(ThylAPP)23Sdz (APP23) animals, a transgenic mouse…

  4. Spatial and temporal characteristics of optimum process noise values of tropospheric parameters for kinematic analysis of Global Navigation Satellite System (GNSS) sites in Japan

    NASA Astrophysics Data System (ADS)

    Hirata, Yu'ichiro; Ohta, Yusaku

    2016-12-01

    Kinematic analysis of Global Navigation Satellite System (GNSS) data is useful for the extraction of crustal deformation phenomena occurring over short timescales ranging from seconds to 1 day, such as coseismic and postseismic deformation following large earthquakes. However, a fundamental challenge in kinematic GNSS analysis is to separate unknown parameters, such as site coordinate and tropospheric parameters, due to the strong correlation between them. In this study, we assessed the spatial and temporal characteristics of process noise for unknown tropospheric parameters such as zenith wet tropospheric delay and tropospheric gradient by means of kinematic precise point positioning analysis using Kalman filtering across the Japanese nationwide continuous GNSS network. We estimated kinematic site coordinate time series under different process noise combinations of zenith wet tropospheric delay and tropospheric gradient. The spatial distribution of the optimum process noise value for the zenith wet tropospheric parameter with vertical site coordinate time series clearly showed regional characteristics. In comparison with the wet tropospheric parameter, the spatial characteristics of the tropospheric gradient parameter are less well defined within the scale of the GNSS network. The temporal characteristics of the optimum process noise parameters for each site coordinate component at specific sites indicated a clear annual pattern in the tropospheric gradient parameter for the horizontal components. Finally, we assessed the effects on the kinematic GNSS site coordinate time series of optimizing tropospheric parameter process noise. Compared with recommended process noise values from previous studies, the use of estimated "common" optimum process noise values improved the standard deviation of coordinate time series for the majority of stations. These results clearly indicate that the use of appropriate process noise values is important for kinematic GNSS analysis

  5. Neural correlates of forward planning in a spatial decision task in humans

    PubMed Central

    Simon, Dylan Alexander; Daw, Nathaniel D.

    2011-01-01

    Although reinforcement learning (RL) theories have been influential in characterizing the brain’s mechanisms for reward-guided choice, the predominant temporal difference (TD) algorithm cannot explain many flexible or goal-directed actions that have been demonstrated behaviorally. We investigate such actions by contrasting an RL algorithm that is model-based, in that it relies on learning a map or model of the task and planning within it, to traditional model-free TD learning. To distinguish these approaches in humans, we used fMRI in a continuous spatial navigation task, in which frequent changes to the layout of the maze forced subjects continually to relearn their favored routes, thereby exposing the RL mechanisms employed. We sought evidence for the neural substrates of such mechanisms by comparing choice behavior and BOLD signals to decision variables extracted from simulations of either algorithm. Both choices and value-related BOLD signals in striatum, though most often associated with TD learning, were better explained by the model-based theory. Further, predecessor quantities for the model-based value computation were correlated with BOLD signals in the medial temporal lobe and frontal cortex. These results point to a significant extension of both the computational and anatomical substrates for RL in the brain. PMID:21471389

  6. 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

  7. Using machine learning to blend human and robot controls for assisted wheelchair navigation.

    PubMed

    Goil, Aditya; Derry, Matthew; Argall, Brenna D

    2013-06-01

    This work presents an algorithm for collaborative control of an assistive semi-autonomous wheelchair. Our approach is based on a statistical machine learning technique to learn task variability from demonstration examples. The algorithm has been developed in the context of shared-control powered wheelchairs that provide assistance to individuals with impairments that affect their control in challenging driving scenarios, like doorway navigation. We validate our algorithm within a simulation environment, and find that with relatively few demonstrations, our approach allows for safe traversal of the doorway while maintaining a high level of user control.

  8. Human factors evaluation of a dynamic channel depiction of navigation procedures in SVS displays

    NASA Astrophysics Data System (ADS)

    Pschierer, C.; Schiefele, J.; Howland, D.; Barraci, N.; Sindlinger, A.; Klingauf, U.

    2007-04-01

    Synthetic vision systems (SVS) are studied for some time to improve pilot's situational awareness and lower their workload. Early systems just displayed a virtual outside view of terrain, obstacles or airport elements as it could also be perceived through the cockpit windows in absence of haze, fog or any other factors impairing visibility. Required digital terrain, obstacle and airport databases have been developed and standardized by Jeppesen as part of the NASA Aviation Safety Program. Newer SVS displays also introduced different kinds of flight guidance symbology to help pilots to improve the overall flight precision. The method studied in this paper is to display navigation procedures in the form of guidance channels. First releases of the described system used static channels, generated once at the startup at the system or even offline. While this approach is very resource friendly for the avionics hardware, it does not consider the users, which want the system to respond to the current flight conditions dynamically. Therefore, a new application has been developed which generates both the general channel trajectory as well as the channel depiction in a fully dynamic way while the pilot flies a navigation procedure.

  9. Hippocampus and subregions of the dorsal striatum respond differently to a behavioral strategy change on a spatial navigation task

    PubMed Central

    Regier, Paul S.; Amemiya, Seiichiro

    2015-01-01

    Goal-directed and habit-based behaviors are driven by multiple but dissociable decision making systems involving several different brain areas, including the hippocampus and dorsal striatum. On repetitive tasks, behavior transitions from goal directed to habit based with experience. Hippocampus has been implicated in initial learning and dorsal striatum in automating behavior, but recent studies suggest that subregions within the dorsal striatum have distinct roles in mediating habit-based and goal-directed behavior. We compared neural activity in the CA1 region of hippocampus with anterior dorsolateral and posterior dorsomedial striatum in rats on a spatial choice task, in which subjects experienced reward delivery changes that forced them to adjust their behavioral strategy. Our results confirm the importance of the hippocampus in evaluating predictive steps during goal-directed behavior, while separate circuits in the basal ganglia integrated relevant information during automation of actions and recognized when new behaviors were needed to continue obtaining rewards. PMID:26084902

  10. Human short-term spatial memory: precision predicts capacity.

    PubMed

    Banta Lavenex, Pamela; Boujon, Valérie; Ndarugendamwo, Angélique; Lavenex, Pierre

    2015-03-01

    Here, we aimed to determine the capacity of human short-term memory for allocentric spatial information in a real-world setting. Young adults were tested on their ability to learn, on a trial-unique basis, and remember over a 1-min interval the location(s) of 1, 3, 5, or 7 illuminating pads, among 23 pads distributed in a 4m×4m arena surrounded by curtains on three sides. Participants had to walk to and touch the pads with their foot to illuminate the goal locations. In contrast to the predictions from classical slot models of working memory capacity limited to a fixed number of items, i.e., Miller's magical number 7 or Cowan's magical number 4, we found that the number of visited locations to find the goals was consistently about 1.6 times the number of goals, whereas the number of correct choices before erring and the number of errorless trials varied with memory load even when memory load was below the hypothetical memory capacity. In contrast to resource models of visual working memory, we found no evidence that memory resources were evenly distributed among unlimited numbers of items to be remembered. Instead, we found that memory for even one individual location was imprecise, and that memory performance for one location could be used to predict memory performance for multiple locations. Our findings are consistent with a theoretical model suggesting that the precision of the memory for individual locations might determine the capacity of human short-term memory for spatial information. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. [Human body meridian spatial decision support system for clinical treatment and teaching of acupuncture and moxibustion].

    PubMed

    Wu, Dehua

    2016-01-01

    The spatial position and distribution of human body meridian are expressed limitedly in the decision support system (DSS) of acupuncture and moxibustion at present, which leads to the failure to give the effective quantitative analysis on the spatial range and the difficulty for the decision-maker to provide a realistic spatial decision environment. Focusing on the limit spatial expression in DSS of acupuncture and moxibustion, it was proposed that on the basis of the geographic information system, in association of DSS technology, the design idea was developed on the human body meridian spatial DSS. With the 4-layer service-oriented architecture adopted, the data center integrated development platform was taken as the system development environment. The hierarchical organization was done for the spatial data of human body meridian via the directory tree. The structured query language (SQL) server was used to achieve the unified management of spatial data and attribute data. The technologies of architecture, configuration and plug-in development model were integrated to achieve the data inquiry, buffer analysis and program evaluation of the human body meridian spatial DSS. The research results show that the human body meridian spatial DSS could reflect realistically the spatial characteristics of the spatial position and distribution of human body meridian and met the constantly changeable demand of users. It has the powerful spatial analysis function and assists with the scientific decision in clinical treatment and teaching of acupuncture and moxibustion. It is the new attempt to the informatization research of human body meridian.

  12. 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

  13. Training-dependent decay in performance produced by the neuroleptic cis(Z)-flupentixol on spatial navigation by rats in a swimming pool.

    PubMed

    Whishaw, I Q; Mittleman, G; Evenden, J L

    1989-01-01

    Rats were trained on place or cue spatial navigation tasks in a swimming pool and then given the neuroleptic, alpha-flupentixol. Initial experiments showed that regardless of testing schedule, including blocks of trials given concurrently or separated by 7 or 30 days, drugged rats showed a trial-by-trial decay in latency and accuracy of responding although they continued to swim. The rate of decay increased with increases in drug dosage. Further experiments showed that: 1) Performance decay was specifically related to conditioned components of the test environment. Animals required to swim in a different test, or to struggle, showed less decay than rats exposed to the test platform only or required to perform all aspects of the task. 2) Decay was not due to nonspecific effects of neuroleptic treatment because rats injected and replaced in their home cage, and then subsequently reinjected and tested performed like rats treated and tested for the first time. 3) A trial-dependent decay of performance was also obtained in hippocampectomized and decorticate rats, suggesting that at least part of the major action of the drug is on subcortical systems. The results are discussed with respect to hypotheses of neuroleptic action and with respect to their possible relevance to experience-dependent changes in animal analogues of Parkinson's disease. Finally, it is suggested that behavior may be organized in subsystems, which when active, become selectively sensitive to neuroleptics.

  14. Dynamic Spatial Hearing by Human and Robot Listeners

    NASA Astrophysics Data System (ADS)

    Zhong, Xuan

    This study consisted of several related projects on dynamic spatial hearing by both human and robot listeners. The first experiment investigated the maximum number of sound sources that human listeners could localize at the same time. Speech stimuli were presented simultaneously from different loudspeakers at multiple time intervals. The maximum of perceived sound sources was close to four. The second experiment asked whether the amplitude modulation of multiple static sound sources could lead to the perception of auditory motion. On the horizontal and vertical planes, four independent noise sound sources with 60° spacing were amplitude modulated with consecutively larger phase delay. At lower modulation rates, motion could be perceived by human listeners in both cases. The third experiment asked whether several sources at static positions could serve as "acoustic landmarks" to improve the localization of other sources. Four continuous speech sound sources were placed on the horizontal plane with 90° spacing and served as the landmarks. The task was to localize a noise that was played for only three seconds when the listener was passively rotated in a chair in the middle of the loudspeaker array. The human listeners were better able to localize the sound sources with landmarks than without. The other experiments were with the aid of an acoustic manikin in an attempt to fuse binaural recording and motion data to localize sounds sources. A dummy head with recording devices was mounted on top of a rotating chair and motion data was collected. The fourth experiment showed that an Extended Kalman Filter could be used to localize sound sources in a recursive manner. The fifth experiment demonstrated the use of a fitting method for separating multiple sounds sources.

  15. Navigation lights color study

    NASA Astrophysics Data System (ADS)

    Barbosa, Jose G.; Alberg, Matthew T.

    2015-05-01

    The chromaticity of navigation lights are defined by areas on the International Commission on Illumination (CIE) 1931 chromaticity diagram. The corner coordinates for these areas are specified in the International Regulations for Prevention of Collisions at Sea, 1972 (72 COLREGS). The navigation light's color of white, red, green, and yellow are bounded by these areas. The chromaticity values specified by the COLREGS for navigation lights were intended for the human visual system (HVS). The HVS can determine the colors of these lights easily under various conditions. For digital color camera imaging systems the colors of these lights are dependent on the camera's color spectral sensitivity, settings, and color correction. At night the color of these lights are used to quickly determine the relative course of vessels. If these lights are incorrectly identified or there is a delay in identifying them this could be a potential safety of ship concern. Vessels that use camera imaging systems exclusively for sight, at night, need to detect, identify, and discriminate navigation lights for navigation and collision avoidance. The introduction of light emitting diode (LED) lights and lights with different spectral signatures have the potential to be imaged very differently with an RGB color filter array (CFA) color camera than with the human eye. It has been found that some green navigation lights' images appear blue verse green. This has an impact on vessels that use camera imaging systems exclusively for navigation. This paper will characterize color cameras ability to properly reproducing navigation lights' color and survey a set of navigation light to determine if they conform to the COLREGS.

  16. Inertial Navigation

    DTIC Science & Technology

    also been well-known for some time. However, inertial navigation systems (called inertial guidance systems in rocket technology) which are composed of... navigation technology has developed rapidly, and the precision of inertial navigation has increased greatly. In 1944, the ’V-2’ rocket made the first...gyroscopes, accelerometers, and electronic computers have only been on the market for a little over twenty years. In the past twenty years, inertial

  17. The Navigation Guide—Evidence-Based Medicine Meets Environmental Health: Systematic Review of Human Evidence for PFOA Effects on Fetal Growth

    PubMed Central

    Sutton, Patrice; Atchley, Dylan S.; Koustas, Erica; Lam, Juleen; Sen, Saunak; Robinson, Karen A.; Axelrad, Daniel A.; Woodruff, Tracey J.

    2014-01-01

    Background: The Navigation Guide methodology was developed to meet the need for a robust method of systematic and transparent research synthesis in environmental health science. We conducted a case study systematic review to support proof of concept of the method. Objective: We applied the Navigation Guide systematic review methodology to determine whether developmental exposure to perfluorooctanoic acid (PFOA) affects fetal growth in humans. Methods: We applied the first 3 steps of the Navigation Guide methodology to human epidemiological data: 1) specify the study question, 2) select the evidence, and 3) rate the quality and strength of the evidence. We developed a protocol, conducted a comprehensive search of the literature, and identified relevant studies using prespecified criteria. We evaluated each study for risk of bias and conducted meta-analyses on a subset of studies. We rated quality and strength of the entire body of human evidence. Results: We identified 18 human studies that met our inclusion criteria, and 9 of these were combined through meta-analysis. Through meta-analysis, we estimated that a 1-ng/mL increase in serum or plasma PFOA was associated with a –18.9 g (95% CI: –29.8, –7.9) difference in birth weight. We concluded that the risk of bias across studies was low, and we assigned a “moderate” quality rating to the overall body of human evidence. Conclusion: On the basis of this first application of the Navigation Guide systematic review methodology, we concluded that there is “sufficient” human evidence that developmental exposure to PFOA reduces fetal growth. Citation: Johnson PI, Sutton P, Atchley DS, Koustas E, Lam J, Sen S, Robinson KA, Axelrad DA, Woodruff TJ. 2014. The Navigation Guide—evidence-based medicine meets environmental health: systematic review of human evidence for PFOA effects on fetal growth. Environ Health Perspect 122:1028–1039; http://dx.doi.org/10.1289/ehp.1307893 PMID:24968388

  18. Integrated processing of spatial cues in human auditory cortex.

    PubMed

    Salminen, Nelli H; Takanen, Marko; Santala, Olli; Lamminsalo, Jarkko; Altoè, Alessandro; Pulkki, Ville

    2015-09-01

    Human sound source localization relies on acoustical cues, most importantly, the interaural differences in time and level (ITD and ILD). For reaching a unified representation of auditory space the auditory nervous system needs to combine the information provided by these two cues. In search for such a unified representation, we conducted a magnetoencephalography (MEG) experiment that took advantage of the location-specific adaptation of the auditory cortical N1 response. In general, the attenuation caused by a preceding adaptor sound to the response elicited by a probe depends on their spatial arrangement: if the two sounds coincide, adaptation is stronger than when the locations differ. Here, we presented adaptor-probe pairs that contained different localization cues, for instance, adaptors with ITD and probes with ILD. We found that the adaptation of the N1 amplitude was location-specific across localization cues. This result can be explained by the existence of auditory cortical neurons that are sensitive to sound source location independent on which cue, ITD or ILD, provides the location information. Such neurons would form a cue-independent, unified representation of auditory space in human auditory cortex.

  19. Flow distributions and spatial correlations in human brain capillary networks

    NASA Astrophysics Data System (ADS)

    Lorthois, Sylvie; Peyrounette, Myriam; Larue, Anne; Le Borgne, Tanguy

    2015-11-01

    The vascular system of the human brain cortex is composed of a space filling mesh-like capillary network connected upstream and downstream to branched quasi-fractal arterioles and venules. The distribution of blood flow rates in these networks may affect the efficiency of oxygen transfer processes. Here, we investigate the distribution and correlation properties of blood flow velocities from numerical simulations in large 3D human intra-cortical vascular network (10000 segments) obtained from an anatomical database. In each segment, flow is solved from a 1D non-linear model taking account of the complex rheological properties of blood flow in microcirculation to deduce blood pressure, blood flow and red blood cell volume fraction distributions throughout the network. The network structural complexity is found to impart broad and spatially correlated Lagrangian velocity distributions, leading to power law transit time distributions. The origins of this behavior (existence of velocity correlations in capillary networks, influence of the coupling with the feeding arterioles and draining veins, topological disorder, complex blood rheology) are studied by comparison with results obtained in various model capillary networks of controlled disorder. ERC BrainMicroFlow GA615102, ERC ReactiveFronts GA648377.

  20. Impact of human interventions on mangrove ecosystem in spatial perspective

    NASA Astrophysics Data System (ADS)

    Rasyid, Abd.; Akbar AS, M.; Nurdin, Nurjannah; Jaya, Ilham; Ibrahim

    2016-11-01

    Climate change components that affect mangroves include changes in sea level, high water events, storms, precipitation, temperature, and oceanic circulation. Cumulative impacts of these factors have a distinct synergy with respect to an accelerated rate of mangrove degradation. development of coastal agricultural land and shrimp farming ponds in intertidal areas are considered as the major factors behind mangrove delineation. There is no agreement for the extensive of mangrove forest in Indonesia, but invarious forums it is usually used the number of 4.25 million ha for that. At approximately 9 years ago, the extensive vast of mangrove forest in Indonesia was about 4.13 million ha but now it is only 2.49 million ha (60%). The methodology of this study consisted of two main steps: (1) image analysis, and (2) post classification. The aim of this study is to analysis the human intervention base on spatial dynamic of mangrove. The study site was selected Sagara island in Spermonde Archipelago. The results of analyze shows that decreasing of mangrove is caused human intervention.

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  3. Spatial decisions and cognitive strategies of monkeys and humans based on abstract spatial stimuli in rotation test.

    PubMed

    Nekovarova, Tereza; Nedvidek, Jan; Klement, Daniel; Bures, Jan

    2009-09-08

    We showed previously that macaque monkeys (Macaca mulatta) could orient in real space using abstract visual stimuli presented on a computer screen. They made correct choices according to both spatial stimuli (designed as an abstract representation of a real space) and nonspatial stimuli (pictures lacking any inner configuration information). However, we suggested that there were differences in processing spatial and nonspatial stimuli. In the present experiment we show that monkeys could also use as a cue abstract spatial stimuli rotated with respect to the real response space. We studied the ability of monkeys to decode abstract spatial information provided in one spatial frame (computer screen) and to perform spatial choices in another spatial frame (touch panel separated from the screen). We analyzed how the monkeys were affected by the type of training, whether they perceived the stimuli as "spatial" or "nonspatial," and which cues they used to decode them. We compared humans to monkeys in a similar test to find out which cognitive strategy they used and whether they perceive spatial stimuli in the same way. We demonstrated that there were two possible strategies to solve the task, simple "fitting" ignoring rotations and "remapping," when the stimulus was represented as an "abstract space" per se.

  4. Transillumination spatially modulated illumination microscopy for human chromosome imaging

    NASA Astrophysics Data System (ADS)

    Pitris, Costas; Heracleous, Peter; Patsalis, Philippos

    2005-03-01

    Human chromosome analysis is an essential task in cytogenetics, especially in prenatal screening, genetic syndrome diagnosis, cancer pathology research and mutagen dosimetry. Chromosomal analysis begins with the creation of a karyotype, which is a layout of chromosome images organized by decreasing size in pairs. Both manual and automatic classification of chromosomes are limited by the resolution of the microscope and imaging system used. One way to improve the results of classification and even detect subtleties now remaining undetected, is to enhance the resolution of the images. It is possible to achieve lateral resolution beyond the classical limit, by using spatially modulated illumination (SMI) in a wide-field, non-confocal microscope. In this case, the sample is illuminated with spatially modulated light, which makes normally inaccessible high-resolution information visible in the observed image by shifting higher frequencies within the OTF limits of the microscope. Although, SMI microscopes have been reported in the past, this manuscript reports the development of a transillumination microscope for opaque, non-fluorescent samples. The illumination path consisted of a light source illuminating a ruled grating which was subsequently imaged on the sample. The grating was mounted on a rotating and translating stage so that the magnification and rotation of the pattern could be adjusted. The imaging lens was a 1.25 NA oil immersion objective. Test samples showed resolution improvement, as judged from a comparison of the experimentally obtained FWHM. Further studies using smaller fringe distance or laser interference pattern illumination will be evaluated to further optimize the SMI results.

  5. Micro Navigator

    NASA Technical Reports Server (NTRS)

    Blaes, B. R.; Kia, T.; Chau, S. N.

    2001-01-01

    Miniature high-performance low-mass space avionics systems are desired for planned future outer planetary exploration missions (i.e. Europa Orbiter/Lander, Pluto-Kuiper Express). The spacecraft fuel and mass requirements enabling orbit insertion is the driving requirement. The Micro Navigator is an integrated autonomous Guidance, Navigation & Control (GN&C)micro-system that would provide the critical avionics function for navigation, pointing, and precision landing. The Micro Navigator hardware and software allow fusion of data from multiple sensors to provide a single integrated vehicle state vector necessary for six degrees of freedom GN&C. The benefits of this MicroNavigator include: 1) The Micro Navigator employs MEMS devices that promise orders of magnitude reductions in mass power and volume of inertial sensors (accelerometers and gyroscopes), celestial sensing devices (startracker, sun sensor), and computing element; 2) The highly integrated nature of the unit will reduce the cost of flight missions. a) The advanced miniaturization technologies employed by the Micro Navigator lend themselves to mass production, and therefore will reduce production cost of spacecraft. b) The integral approach simplifies interface issues associated with discrete components and reduces cost associated with integration and test of multiple components; and 3) The integration of sensors and processing elements into a single unit will allow the Micro Navigator to encapsulate attitude information and determination functions into a single object. This is particularly beneficial for object-oriented software architectures that are used in advanced spacecraft. Additional information is contained in the original extended abstract.

  6. Micro Navigator

    NASA Astrophysics Data System (ADS)

    Blaes, B. R.; Kia, T.; Chau, S. N.

    2001-01-01

    Miniature high-performance low-mass space avionics systems are desired for planned future outer planetary exploration missions (i.e. Europa Orbiter/Lander, Pluto-Kuiper Express). The spacecraft fuel and mass requirements enabling orbit insertion is the driving requirement. The Micro Navigator is an integrated autonomous Guidance, Navigation & Control (GN&C)micro-system that would provide the critical avionics function for navigation, pointing, and precision landing. The Micro Navigator hardware and software allow fusion of data from multiple sensors to provide a single integrated vehicle state vector necessary for six degrees of freedom GN&C. The benefits of this MicroNavigator include: 1) The Micro Navigator employs MEMS devices that promise orders of magnitude reductions in mass power and volume of inertial sensors (accelerometers and gyroscopes), celestial sensing devices (startracker, sun sensor), and computing element; 2) The highly integrated nature of the unit will reduce the cost of flight missions. a) The advanced miniaturization technologies employed by the Micro Navigator lend themselves to mass production, and therefore will reduce production cost of spacecraft. b) The integral approach simplifies interface issues associated with discrete components and reduces cost associated with integration and test of multiple components; and 3) The integration of sensors and processing elements into a single unit will allow the Micro Navigator to encapsulate attitude information and determination functions into a single object. This is particularly beneficial for object-oriented software architectures that are used in advanced spacecraft. Additional information is contained in the original extended abstract.

  7. Cooperative interactions between hippocampal and striatal systems support flexible navigation

    PubMed Central

    Brown, Thackery I; Ross, Robert S; Tobyne, Sean M; Stern, Chantal E

    2012-01-01

    Research in animals and humans has demonstrated that the hippocampus is critical for retrieving distinct representations of overlapping sequences of information. There is recent evidence that the caudate nucleus and orbitofrontal cortex are also involved in disambiguation of overlapping spatial representations. The hippocampus and caudate are functionally distinct regions, but both have anatomical links with the orbitofrontal cortex. The present study used an fMRI-based functional connectivity analysis in humans to examine the functional relationship between the hippocampus, caudate, and orbitofrontal cortex when participants use contextual information to navigate well-learned spatial routes which share common elements. Participants were trained outside the scanner to navigate virtual mazes from a first-person perspective. Overlapping condition mazes began and ended at distinct locations, but converged in the middle to share some hallways with another maze. Non-overlapping condition mazes did not share any hallways with any other maze. Successful navigation through the overlapping hallways required contextual information identifying the current navigational route to guide the appropriate response for a given trial. Results revealed greater functional connectivity between the hippocampus, caudate, and orbitofrontal cortex for overlapping mazes compared to non-overlapping mazes. The current findings suggest that the hippocampus and caudate interact with prefrontal structures cooperatively for successful contextually-dependent navigation. PMID:22266411

  8. PATIENT NAVIGATION

    PubMed Central

    Wells, Kristen J.; Battaglia, Tracy A.; Dudley, Donald J.; Garcia, Roland; Greene, Amanda; Calhoun, Elizabeth; Mandelblatt, Jeanne S.; Paskett, Electra D.; Raich, Peter C.

    2008-01-01

    Background First implemented in 1990, patient navigation interventions are emerging as an approach to reduce cancer disparities. However, there is lack of consensus about how patient navigation is defined, what patient navigators do, and what their qualifications should be. Little is known about the efficacy and cost effectiveness of patient navigation. Methods We conducted a qualitative synthesis of published literature on cancer patient navigation. Using the keywords “navigator” or “navigation” and “cancer,” we identified 45 articles from Pubmed and reference searches that were published or in press through October 2007. 16 provided data on efficacy of navigation in improving timeliness and receipt of cancer screening, diagnostic follow-up care, and treatment. Patient navigation services are defined and differentiated from other outreach services. Results Overall there is evidence for some degree of efficacy for patient navigation in increasing participation in cancer screening and adherence to diagnostic follow-up care following an abnormality, with increases in screening ranging from 10.8% to 17.1% and increases in adherence to diagnostic follow-up care ranging from 21% to 29.2%, when compared to control patients. There is less evidence regarding efficacy of patient navigation in reducing either late stage cancer diagnosis or delays in initiation of cancer treatment or improving outcomes during cancer survivorship. There were methodological limitations in most studies, such as lack of control groups, small sample sizes, and contamination with other interventions. Conclusions Although cancer-related patient navigation interventions are being increasingly adopted across the U.S. and Canada, further research is necessary to evaluate their efficacy and cost-effectiveness in improving cancer care. PMID:18780320

  9. On the identification and establishment of topological spatial relations by autonomous systems

    NASA Astrophysics Data System (ADS)

    Miguel-Tomé, Sergio; Fernández-Caballero, Antonio

    2014-07-01

    Human beings use spatial relations to describe many daily tasks in their language. For a mobile robot to be useful in daily life, it is necessary to have navigation algorithms capable of identifying and establishing spatial relations. To date in robotics, the navigation problem has been thoroughly researched as a task of guiding a robot from one spatial coordinate to another. Therefore, there is a difference in degree of abstraction between the language of human beings and the algorithms used in robot navigation. This article introduces a piece of research performed on the use of topological relations for the formalisation of spatial relations and navigation. So far, topological relations have been applied widely in geographical information systems and also in spatial logics. There are some proposals in robot navigation which use them for planning but there is no research about making decision in robot navigation. Our research focuses on decision-making methods to establish spatial relations. The main result is a new heuristic, called the Heuristic of Topological Qualitative Semantics (HTQS), which allows the identification and establishment of spatial relations decision-making from a set of actions. To demonstrate its effectiveness, HTQS has been implemented in the form of agents that can move in a two-dimensional virtual environment. HTQS opens a new door to designing algorithms for navigation based on the identification and establishment of spatial relations.

  10. Spatial Construction Skills of Chimpanzees ("Pan Troglodytes") and Young Human Children ("Homo Sapiens Sapiens")

    ERIC Educational Resources Information Center

    Poti, Patrizia; Hayashi, Misato; Matsuzawa, Tetsuro

    2009-01-01

    Spatial construction tasks are basic tests of visual-spatial processing. Two studies have assessed spatial construction skills in chimpanzees (Pan troglodytes) and young children (Homo sapiens sapiens) with a block modelling task. Study 1a subjects were three young chimpanzees and five adult chimpanzees. Study 1b subjects were 30 human children…

  11. Spatial Construction Skills of Chimpanzees ("Pan Troglodytes") and Young Human Children ("Homo Sapiens Sapiens")

    ERIC Educational Resources Information Center

    Poti, Patrizia; Hayashi, Misato; Matsuzawa, Tetsuro

    2009-01-01

    Spatial construction tasks are basic tests of visual-spatial processing. Two studies have assessed spatial construction skills in chimpanzees (Pan troglodytes) and young children (Homo sapiens sapiens) with a block modelling task. Study 1a subjects were three young chimpanzees and five adult chimpanzees. Study 1b subjects were 30 human children…

  12. Analyzing the spatial and temporal distribution of human brucellosis in Azerbaijan (1995 - 2009) using spatial and spatio-temporal statistics

    PubMed Central

    2012-01-01

    Background Human brucellosis represents a significant burden to public and veterinary health globally, including the republic of Azerbaijan. The purpose of this study was to examine and describe the spatial and temporal aspects of the epidemiology of human brucellosis in Azerbaijan from 1995 to 2009. Methods A Geographic information system (GIS) was used to identify potential changes in the spatial and temporal distribution of human brucellosis in Azerbaijan during the study period. Epidemiological information on the age, gender, date, and location of incident cases were obtained from disease registries housed at the Republican Anti-Plague station in Baku. Cumulative incidences per 100,000 populations were calculated at the district level for three, 5-year periods. Spatial and temporal cluster analyses were performed using the Local Moran’s I and the Ederer-Myer-Mantel (EMM) test. Results A total of 7,983 cases of human brucellosis were reported during the 15-year study period. Statistically significant spatial clusters were identified in each of three, five year time periods with cumulative incidence rates ranging from 101.1 (95% CI: 82.8, 124.3) to 203.0 (95% CI; 176.4, 234.8). Spatial clustering was predominant in the west early in the study during period 1 and then in the east during periods 2 and 3. The EMM test identified a greater number of statistically significant temporal clusters in period 1 (1995 to 1999). Conclusion These results suggest that human brucellosis persisted annually in Azerbaijan across the study period. The current situation necessitates the development of appropriate surveillance aimed at improving control and mitigation strategies in order to help alleviate the current burden of disease on the population. Areas of concern identified as clusters by the spatial-temporal statistical analyses can provide a starting point for implementing targeted intervention efforts. PMID:22873196

  13. Analyzing the spatial and temporal distribution of human brucellosis in Azerbaijan (1995 - 2009) using spatial and spatio-temporal statistics.

    PubMed

    Abdullayev, Rakif; Kracalik, Ian; Ismayilova, Rita; Ustun, Narmin; Talibzade, Ayden; Blackburn, Jason K

    2012-08-08

    Human brucellosis represents a significant burden to public and veterinary health globally, including the republic of Azerbaijan. The purpose of this study was to examine and describe the spatial and temporal aspects of the epidemiology of human brucellosis in Azerbaijan from 1995 to 2009. A Geographic information system (GIS) was used to identify potential changes in the spatial and temporal distribution of human brucellosis in Azerbaijan during the study period. Epidemiological information on the age, gender, date, and location of incident cases were obtained from disease registries housed at the Republican Anti-Plague station in Baku. Cumulative incidences per 100,000 populations were calculated at the district level for three, 5-year periods. Spatial and temporal cluster analyses were performed using the Local Moran's I and the Ederer-Myer-Mantel (EMM) test. A total of 7,983 cases of human brucellosis were reported during the 15-year study period. Statistically significant spatial clusters were identified in each of three, five year time periods with cumulative incidence rates ranging from 101.1 (95% CI: 82.8, 124.3) to 203.0 (95% CI; 176.4, 234.8). Spatial clustering was predominant in the west early in the study during period 1 and then in the east during periods 2 and 3. The EMM test identified a greater number of statistically significant temporal clusters in period 1 (1995 to 1999). These results suggest that human brucellosis persisted annually in Azerbaijan across the study period. The current situation necessitates the development of appropriate surveillance aimed at improving control and mitigation strategies in order to help alleviate the current burden of disease on the population. Areas of concern identified as clusters by the spatial-temporal statistical analyses can provide a starting point for implementing targeted intervention efforts.

  14. Spatial distribution of human-caused forest fires in Galicia (NW Spain)

    Treesearch

    M. L. Chas-Amil; J. Touza; P. Prestemon

    2010-01-01

    It is crucial for fire prevention policies to assess the spatial patterns of human-started fires and their relationship with geographical and socioeconomic aspects. This study uses fire reports for the period 1988-2006 in Galicia, Spain, to analyze the spatial distribution of human-induced fire risk attending to causes and underlying motivations associated with fire...

  15. Network mechanisms of hippocampal laterality, place coding, and goal-directed navigation.

    PubMed

    Kitanishi, Takuma; Ito, Hiroshi T; Hayashi, Yuichiro; Shinohara, Yoshiaki; Mizuseki, Kenji; Hikida, Takatoshi

    2017-03-01

    The hippocampus and associated structures are responsible for episodic memory in humans. In rodents, the most prominent behavioral correlate of hippocampal neural activity is place coding, which is thought to underlie spatial navigation. While episodic memory is considered to be unique to humans in a restricted context, it has been proposed that the same neural circuitry and algorithms that enable spatial coding and navigation also support episodic memory. Here we review the recent progress in neural circuit mechanisms of hippocampal activity by introducing several topics: (1) cooperation and specialization of the bilateral hippocampi, (2) the role of synaptic plasticity in gamma phase-locking of spikes and place cell formation, (3) impaired goal-related activity and oscillations in a mouse model of mental disorders, and (4) a prefrontal-thalamo-hippocampal circuit for goal-directed spatial navigation.

  16. 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

  17. Basal Forebrain Atrophy Contributes to Allocentric Navigation Impairment in Alzheimer's Disease Patients.

    PubMed

    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.

  18. Impairment of auditory spatial localization in congenitally blind human subjects.

    PubMed

    Gori, Monica; Sandini, Giulio; Martinoli, Cristina; Burr, David C

    2014-01-01

    Several studies have demonstrated enhanced auditory processing in the blind, suggesting that they compensate their visual impairment in part with greater sensitivity of the other senses. However, several physiological studies show that early visual deprivation can impact negatively on auditory spatial localization. Here we report for the first time severely impaired auditory localization in the congenitally blind: thresholds for spatially bisecting three consecutive, spatially-distributed sound sources were seriously compromised, on average 4.2-fold typical thresholds, and half performing at random. In agreement with previous studies, these subjects showed no deficits on simpler auditory spatial tasks or with auditory temporal bisection, suggesting that the encoding of Euclidean auditory relationships is specifically compromised in the congenitally blind. It points to the importance of visual experience in the construction and calibration of auditory spatial maps, with implications for rehabilitation strategies for the congenitally blind.

  19. Enabling Future Science and Human Exploration with NASA's Next Generation near Earth and Deep Space Communications and Navigation Architecture

    NASA Technical Reports Server (NTRS)

    Reinhart, Richard C.; Schier, James S.; Israel, David J.; Tai, Wallace; Liebrecht, Philip E.; Townes, Stephen A.

    2017-01-01

    The National Aeronautics and Space Administration (NASA) is studying alternatives for the United States space communications architecture through the 2040 timeframe. This architecture provides communication and navigation services to both human exploration and science missions throughout the solar system. Several of NASA's key space assets are approaching their end of design life and major systems are in need of replacement. The changes envisioned in the relay satellite architecture and capabilities around both Earth and Mars are significant undertakings and occur only once or twice each generation, and therefore is referred to as NASA's next generation space communications architecture. NASA's next generation architecture will benefit from technology and services developed over recent years. These innovations will provide missions with new operations concepts, increased performance, and new business and operating models. Advancements in optical communications will enable high-speed data channels and the use of new and more complex science instruments. Modern multiple beam/multiple access technologies such as those employed on commercial high throughput satellites will enable enhanced capabilities for on-demand service, and with new protocols will help provide Internet-like connectivity for cooperative spacecraft to improve data return and coordinate joint mission objectives. On-board processing with autonomous and cognitive networking will play larger roles to help manage system complexity. Spacecraft and ground systems will coordinate among themselves to establish communications, negotiate link connectivity, and learn to share spectrum to optimize resource allocation. Spacecraft will autonomously navigate, plan trajectories, and handle off-nominal events. NASA intends to leverage the ever-expanding capabilities of the satellite communications industry and foster its continued growth. NASA's technology development will complement and extend commercial capabilities

  20. The Navigation Guide - evidence-based medicine meets environmental health: systematic review of human evidence for PFOA effects on fetal growth.

    PubMed

    Johnson, Paula I; Sutton, Patrice; Atchley, Dylan S; Koustas, Erica; Lam, Juleen; Sen, Saunak; Robinson, Karen A; Axelrad, Daniel A; Woodruff, Tracey J

    2014-10-01

    The Navigation Guide methodology was developed to meet the need for a robust method of systematic and transparent research synthesis in environmental health science. We conducted a case study systematic review to support proof of concept of the method. We applied the Navigation Guide systematic review methodology to determine whether developmental exposure to perfluorooctanoic acid (PFOA) affects fetal growth in humans. We applied the first 3 steps of the Navigation Guide methodology to human epidemiological data: 1) specify the study question, 2) select the evidence, and 3) rate the quality and strength of the evidence. We developed a protocol, conducted a comprehensive search of the literature, and identified relevant studies using prespecified criteria. We evaluated each study for risk of bias and conducted meta-analyses on a subset of studies. We rated quality and strength of the entire body of human evidence. We identified 18 human studies that met our inclusion criteria, and 9 of these were combined through meta-analysis. Through meta-analysis, we estimated that a 1-ng/mL increase in serum or plasma PFOA was associated with a -18.9 g (95% CI: -29.8, -7.9) difference in birth weight. We concluded that the risk of bias across studies was low, and we assigned a "moderate" quality rating to the overall body of human evidence. On the basis of this first application of the Navigation Guide systematic review methodology, we concluded that there is "sufficient" human evidence that developmental exposure to PFOA reduces fetal growth.

  1. The Navigation Guide - evidence-based medicine meets environmental health: integration of animal and human evidence for PFOA effects on fetal growth.

    PubMed

    Lam, Juleen; Koustas, Erica; Sutton, Patrice; Johnson, Paula I; Atchley, Dylan S; Sen, Saunak; Robinson, Karen A; Axelrad, Daniel A; Woodruff, Tracey J

    2014-10-01

    The Navigation Guide is a novel systematic review method to synthesize scientific evidence and reach strength of evidence conclusions for environmental health decision making. Our aim was to integrate scientific findings from human and nonhuman studies to determine the overall strength of evidence for the question "Does developmental exposure to perfluorooctanoic acid (PFOA) affect fetal growth in humans?" We developed and applied prespecified criteria to systematically and transparently a) rate the quality of the scientific evidence as "high," "moderate," or "low"; b) rate the strength of the human and nonhuman evidence separately as "sufficient," "limited," "moderate," or "evidence of lack of toxicity"; and c) integrate the strength of the human and nonhuman evidence ratings into a strength of the evidence conclusion. We identified 18 epidemiology studies and 21 animal toxicology studies relevant to our study question. We rated both the human and nonhuman mammalian evidence as "moderate" quality and "sufficient" strength. Integration of these evidence ratings produced a final strength of evidence rating in which review authors concluded that PFOA is "known to be toxic" to human reproduction and development based on sufficient evidence of decreased fetal growth in both human and nonhuman mammalian species. We concluded that developmental exposure to PFOA adversely affects human health based on sufficient evidence of decreased fetal growth in both human and nonhuman mammalian species. The results of this case study demonstrate the application of a systematic and transparent methodology, via the Navigation Guide, for reaching strength of evidence conclusions in environmental health.

  2. 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

  3. Neural mechanisms underlying catastrophic failure in human-machine interaction during aerial navigation.

    PubMed

    Saproo, Sameer; Shih, Victor; Jangraw, David C; Sajda, Paul

    2016-12-01

    We investigated the neural correlates of workload buildup in a fine visuomotor task called the boundary avoidance task (BAT). The BAT has been known to induce naturally occurring failures of human-machine coupling in high performance aircraft that can potentially lead to a crash-these failures are termed pilot induced oscillations (PIOs). We recorded EEG and pupillometry data from human subjects engaged in a flight BAT simulated within a virtual 3D environment. We find that workload buildup in a BAT can be successfully decoded from oscillatory features in the electroencephalogram (EEG). Information in delta, theta, alpha, beta, and gamma spectral bands of the EEG all contribute to successful decoding, however gamma band activity with a lateralized somatosensory topography has the highest contribution, while theta band activity with a fronto-central topography has the most robust contribution in terms of real-world usability. We show that the output of the spectral decoder can be used to predict PIO susceptibility. We also find that workload buildup in the task induces pupil dilation, the magnitude of which is significantly correlated with the magnitude of the decoded EEG signals. These results suggest that PIOs may result from the dysregulation of cortical networks such as the locus coeruleus (LC)-anterior cingulate cortex (ACC) circuit. Our findings may generalize to similar control failures in other cases of tight man-machine coupling where gains and latencies in the control system must be inferred and compensated for by the human operators. A closed-loop intervention using neurophysiological decoding of workload buildup that targets the LC-ACC circuit may positively impact operator performance in such situations.

  4. Neural mechanisms underlying catastrophic failure in human-machine interaction during aerial navigation

    NASA Astrophysics Data System (ADS)

    Saproo, Sameer; Shih, Victor; Jangraw, David C.; Sajda, Paul

    2016-12-01

    Objective. We investigated the neural correlates of workload buildup in a fine visuomotor task called the boundary avoidance task (BAT). The BAT has been known to induce naturally occurring failures of human-machine coupling in high performance aircraft that can potentially lead to a crash—these failures are termed pilot induced oscillations (PIOs). Approach. We recorded EEG and pupillometry data from human subjects engaged in a flight BAT simulated within a virtual 3D environment. Main results. We find that workload buildup in a BAT can be successfully decoded from oscillatory features in the electroencephalogram (EEG). Information in delta, theta, alpha, beta, and gamma spectral bands of the EEG all contribute to successful decoding, however gamma band activity with a lateralized somatosensory topography has the highest contribution, while theta band activity with a fronto-central topography has the most robust contribution in terms of real-world usability. We show that the output of the spectral decoder can be used to predict PIO susceptibility. We also find that workload buildup in the task induces pupil dilation, the magnitude of which is significantly correlated with the magnitude of the decoded EEG signals. These results suggest that PIOs may result from the dysregulation of cortical networks such as the locus coeruleus (LC)—anterior cingulate cortex (ACC) circuit. Significance. Our findings may generalize to similar control failures in other cases of tight man-machine coupling where gains and latencies in the control system must be inferred and compensated for by the human operators. A closed-loop intervention using neurophysiological decoding of workload buildup that targets the LC-ACC circuit may positively impact operator performance in such situations.

  5. Guidance, Navigation and Control (GN&C): Best Practices for Human-Rated Spacecraft Systems

    NASA Technical Reports Server (NTRS)

    Lebsock, Ken; West, John

    2008-01-01

    In 2007 the NESC completed an in-depth assessment to identify, define and document engineering considerations for the Design Development Test and Evaluation (DDT&E) of human-rated spacecraft systems. This study had been requested by the Astronaut Office at JSC to help them to better understand what is required to ensure safe, robust, and reliable human-rated spacecraft systems. The 22 GN&C engineering Best Practices described in this paper are a condensed version of what appears in the NESC Technical Report. These Best Practices cover a broad range from fundamental system architectural considerations to more specific aspects (e.g., stability margin recommendations) of GN&C system design and development. 15 of the Best Practices address the early phases of a GN&C System development project and the remaining 7 deal with the later phases. Some of these Best Practices will cross-over between both phases. We recognize that this set of GN&C Best Practices will not be universally applicable to all projects and mission applications.

  6. Navigating the quagmire: the regulation of human embryonic stem cell research.

    PubMed

    Jones, D G; Towns, C R

    2006-05-01

    Embryonic stem (ES) cell research has garnered almost unprecedented attention. Debate over the boundaries of such research is ongoing, and the regulation of the field varies widely between countries. This article identifies and evaluates the four major positions that emanate from current international regulations. ES cell policies may ultimately impact on public health, and hence they must be both rigorous and transparent. We contend that these goals will only be achieved if policy is both ethically consistent and clinically realistic with regard to the ability to achieve therapeutic goals. We conclude that policies allowing the ongoing extraction of stem cells from spare in vitro fertilization embryos and the creation of embryos for research (within set limitations) cope most adequately with the tension between varying views on the moral status of the human embryo and the therapeutic potential inherent within ES cell research.

  7. Spatial Overlap Between People and Non-human Primates in a Fragmented Landscape.

    PubMed

    Paige, Sarah B; Bleecker, Johanna; Mayer, Jonathan; Goldberg, Tony

    2017-03-01

    In western Uganda, the landscape surrounding Kibale National Park (KNP) contains households, trading centers, roads, fields, and forest fragments. The mosaic arrangement of these landscape features is thought to enhance human-primate interaction, leading to primate population declines and increased bi-directional disease transmission. Using a social-ecological systems research framework that captures the complexity of interaction among people, wildlife, and environment, we studied five forest fragments near KNP and conducted intensive on-the-ground mapping to identify locations of human-primate spatial overlap. Primate locations and human activities were distributed within, on the edges, and far beyond fragment borders. Analysis of shared spaces indicated that 5.5% of human space overlapped with primate spaces, while 69.5% of primate spaces overlapped with human spaces. Nearest neighbor analysis indicated that human activities were significantly spatially clustered within and around individual fragments, as were primate locations. Getis-Ord statistics revealed statistically significant "hotspots" of human activity and primate activity, but only one location where spatial overlap between humans and primates was statistically significant. Human activities associated with collecting fuelwood and other forest products were the primary drivers of human-primate overlap; however, primates also spent time outside of forest fragments in agricultural spaces. These results demonstrate that fragmented landscapes are not uniform with respect to human-primate overlap, and that the implications of human-primate interaction, such as primate population declines and possible cross-species disease transmission, are spatially aggregated.

  8. Multimodal cognitive interface for robot navigation.

    PubMed

    Elmogy, Mohammed; Habel, Christopher; Zhang, Jianwei

    2011-02-01

    To build effective interactions between humans and robots, they should have common ground of understanding that creates realistic expectations and forms the basis communications. An emerging approach to doing this is to create cognitive models of human reasoning and behavior selection. We have developed a robot navigation system that uses both spatial language and graphical representation to describe route-based navigation tasks for a mobile robot. Our proposed route instruction language (RIL) is intended as a semi-formal language for instructing the robot to execute a route in an indoor environment. We implemented an instruction interpreter to process the route description and generate its equivalent symbolic and topological map representations. A topological map is generated to describe relationships among features of the environment in a more abstract form without any absolute reference system to treat the ambiguity which can occur when the robot cannot recognize the current landmark. The symbolic and topological map representations are supplied to other system components as an initial path estimation to guide the robot while it plans its navigation task. We conducted some experiments to evaluate the routes which are written by using the RIL instructions.

  9. Cardiovascular Fitness and Cognitive Spatial Learning in Rodents and in Humans

    PubMed Central

    Barak, Boaz; Feldman, Noa

    2015-01-01

    The association between cardiovascular fitness and cognitive functions in both animals and humans is intensely studied. Research in rodents shows that a higher cardiovascular fitness has beneficial effects on hippocampus-dependent spatial abilities, and the underlying mechanisms were largely teased out. Research into the impact of cardiovascular fitness on spatial learning in humans, however, is more limited, and involves mostly behavioral and imaging studies. Herein, we point out the state of the art in the field of spatial learning and cardiovascular fitness. The differences between the methodologies utilized to study spatial learning in humans and rodents are emphasized along with the neuronal basis of these tasks. Critical gaps in the study of spatial learning in the context of cardiovascular fitness between the two species are discussed. PMID:25227128

  10. Spatial navigation in complex and radial mazes in APP23 animals and neurotrophin signaling as a biological marker of early impairment.

    PubMed

    Hellweg, Rainer; Lohmann, Peter; Huber, Roman; Kühl, Alexander; Riepe, Matthias W

    2006-01-01

    Impairment of hippocampal function precedes frontal and parietal cortex impairment in human Alzheimer's disease (AD). Neurotrophins are critical for behavioral performance and neuronal survival in AD. We used complex and radial mazes to assess spatial orientation and learning in wild-type and B6-Tg(ThylAPP)23Sdz (APP23) animals, a transgenic mouse model of AD. We also assessed brain content of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3). Performance was alike in wild-type and APP23 animals in the radial maze. In contrast, performance in the complex maze was better in wild-type than APP23 animals. Contrary to the wild-type, hippocampal BDNF levels decreased on training in APP23 animals. Hippocampal and frontal cortex NGF levels in APP23 animals correlated with the time to solve the complex maze, but correlated inversely with escape time in wild-type animals. NT-3 levels were alike in wild-type and APP23 animals and were unchanged even after training. Both types of mazes depend on hippocampal integrity to some extent. However, according to the cognitive mapping theory of spatial learning, the complex maze because of the increased complexity of the environment most likely depends more strongly on preserved hippocampal function than the radial maze in the working memory configuration applied here. Greater impairment in complex maze performance than in radial maze performance thus resembles the predominant affliction of the loss of hippocampal function in human AD. NGF and BDNF levels on maze learning are different in wild-type and transgenic animals, indicating that biological markers of AD may be altered on challenge even though equilibrium levels are alike.

  11. Comparison of view-based and reconstruction-based models of human navigational strategy.

    PubMed

    Gootjes-Dreesbach, Luise; Pickup, Lyndsey C; Fitzgibbon, Andrew W; Glennerster, Andrew

    2017-08-01

    There is good evidence that simple animals, such as bees, use view-based strategies to return to a familiar location, whereas humans might use a 3-D reconstruction to achieve the same goal. Assuming some noise in the storage and retrieval process, these two types of strategy give rise to different patterns of predicted errors in homing. We describe an experiment that can help distinguish between these models. Participants wore a head-mounted display to carry out a homing task in immersive virtual reality. They viewed three long, thin, vertical poles and had to remember where they were in relation to the poles before being transported (virtually) to a new location in the scene from where they had to walk back to the original location. The experiment was conducted in both a rich-cue scene (a furnished room) and a sparse scene (no background and no floor or ceiling). As one would expect, in a rich-cue environment, the overall error was smaller, and in this case, the ability to separate the models was reduced. However, for the sparse-cue environment, the view-based model outperforms the reconstruction-based model. Specifically, the likelihood of the experimental data is similar to the likelihood of samples drawn from the view-based model (but assessed under both models), and this is not true for samples drawn from the reconstruction-based model.

  12. Development of Multisensory Spatial Integration and Perception in Humans

    ERIC Educational Resources Information Center

    Neil, Patricia A.; Chee-Ruiter, Christine; Scheier, Christian; Lewkowicz, David J.; Shimojo, Shinsuke

    2006-01-01

    Previous studies have shown that adults respond faster and more reliably to bimodal compared to unimodal localization cues. The current study investigated for the first time the development of audiovisual (A-V) integration in spatial localization behavior in infants between 1 and 10 months of age. We observed infants' head and eye movements in…

  13. Effects of spatial training on transitive inference performance in humans and rhesus monkeys

    PubMed Central

    Gazes, Regina Paxton; Lazareva, Olga F.; Bergene, Clara N.; Hampton, Robert R.

    2015-01-01

    It is often suggested that transitive inference (TI; if A>B and B>C then A>C) involves mentally representing overlapping pairs of stimuli in a spatial series. However, there is little direct evidence to unequivocally determine the role of spatial representation in TI. We tested whether humans and rhesus monkeys use spatial representations in TI by training them to organize seven images in a vertical spatial array. Then, we presented subjects with a TI task using these same images. The implied TI order was either congruent or incongruent with the order of the trained spatial array. Humans in the congruent condition learned premise pairs more quickly, and were faster and more accurate in critical probe tests, suggesting that the spatial arrangement of images learned during spatial training influenced subsequent TI performance. Monkeys first trained in the congruent condition also showed higher test trial accuracy when the spatial and inferred orders were congruent. These results directly support the hypothesis that humans solve TI problems by spatial organization, and suggest that this cognitive mechanism for inference may have ancient evolutionary roots. PMID:25546105

  14. Spontaneous Recovery of Human Spatial Memory in a Virtual Water Maze

    ERIC Educational Resources Information Center

    Luna, David; Martínez, Héctor

    2015-01-01

    The occurrence of spontaneous recovery in human spatial memory was assessed using a virtual environment. In Experiment 1, spatial memory was established by training participants to locate a hidden platform in a virtual water maze using a set of four distal landmarks. In Experiment 2, after learning about the location of a hidden platform, the…

  15. Children's Reading of Printed Text and Hypertext with Navigation Overviews: The Role of Comprehension, Sustained Attention, and Visuo-Spatial Abilities

    ERIC Educational Resources Information Center

    Salmeron, Ladislao; Garcia, Victoria

    2012-01-01

    Hypertexts include new structural features, such as navigable graphical overviews, that dramatically change the way students interact with texts. Nevertheless, at school students traditionally practice literacy skills appropriate for reading and comprehending printed texts. We explored the possibility that those skills might not be the same as the…

  16. INL Autonomous Navigation System

    SciTech Connect

    2005-03-30

    The INL Autonomous Navigation System provides instructions for autonomously navigating a robot. The system permits high-speed autonomous navigation including obstacle avoidance, waypoing navigation and path planning in both indoor and outdoor environments.

  17. Human Parahippocampal Cortex Supports Spatial Binding in Visual Working Memory.

    PubMed

    Dundon, Neil Michael; Katshu, Mohammad Zia Ul Haq; Harry, Bronson; Roberts, Daniel; Leek, E Charles; Downing, Paul; Sapir, Ayelet; Roberts, Craig; d'Avossa, Giovanni

    2017-09-15

    Studies investigating the functional organization of the medial temporal lobe (MTL) suggest that parahippocampal cortex (PHC) generates representations of spatial and contextual information used by the hippocampus in the formation of episodic memories. However, evidence from animal studies also implicates PHC in spatial binding of visual information held in short term, working memory. Here we examined a 46-year-old man (P.J.), after he had recovered from bilateral medial occipitotemporal cortex strokes resulting in ischemic lesions of PHC and hippocampal atrophy, and a group of age-matched healthy controls. When recalling the color of 1 of 2 objects, P.J. misidentified the target when cued by its location, but not shape. When recalling the position of 1 of 3 objects, he frequently misidentified the target, which was cued by its color. Increasing the duration of the memory delay had no impact on the proportion of binding errors, but did significantly worsen recall precision in both P.J. and controls. We conclude that PHC may play a crucial role in spatial binding during encoding of visual information in working memory. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  18. Use of navigation channels by Lake Sturgeon: Does channelization increase vulnerability of fish to ship strikes?

    USGS Publications Warehouse

    Hondorp, Darryl W.; Bennion, David; Roseman, Edward; Holbrook, Christopher; Boase, James C.; Chiotti, Justin A.; Thomas, Michael V.; Wills, Todd C.; Drouin, Richard; Kessel, Steven T.; Krueger, Charles Conrad

    2017-01-01

    Channelization for navigation and flood control has altered the hydrology and bathymetry of many large rivers with unknown consequences for fish species that undergo riverine migrations. In this study, we investigated whether altered flow distributions and bathymetry associated with channelization attracted migrating Lake Sturgeon (Acipenser fulvescens) into commercial navigation channels, potentially increasing their exposure to ship strikes. To address this question, we quantified and compared Lake Sturgeon selection for navigation channels vs. alternative pathways in two multi-channel rivers differentially affected by channelization, but free of barriers to sturgeon movement. Acoustic telemetry was used to quantify Lake Sturgeon movements. Under the assumption that Lake Sturgeon navigate by following primary flow paths, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River were expected to choose navigation channels over alternative pathways and to exhibit greater selection for navigation channels than conspecifics in the less-channelized lower St. Clair River. Consistent with these predictions, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River selected the higher-flow and deeper navigation channels over alternative migration pathways, whereas in the less-channelized lower St. Clair River, individuals primarily used pathways alternative to navigation channels. Lake Sturgeon selection for navigation channels as migratory pathways also was significantly higher in the more-channelized lower Detroit River than in the less-channelized lower St. Clair River. We speculated that use of navigation channels over alternative pathways would increase the spatial overlap of commercial vessels and migrating Lake Sturgeon, potentially enhancing their vulnerability to ship strikes. Results of our study thus demonstrated an association between channelization and the path use of migrating Lake Sturgeon that could prove important for

  19. Use of navigation channels by Lake Sturgeon: Does channelization increase vulnerability of fish to ship strikes?

    PubMed Central

    Bennion, David H.; Roseman, Edward F.; Holbrook, Christopher M.; Boase, James C.; Chiotti, Justin A.; Thomas, Michael V.; Wills, Todd C.; Drouin, Richard G.; Kessel, Steven T.; Krueger, Charles C.

    2017-01-01

    Channelization for navigation and flood control has altered the hydrology and bathymetry of many large rivers with unknown consequences for fish species that undergo riverine migrations. In this study, we investigated whether altered flow distributions and bathymetry associated with channelization attracted migrating Lake Sturgeon (Acipenser fulvescens) into commercial navigation channels, potentially increasing their exposure to ship strikes. To address this question, we quantified and compared Lake Sturgeon selection for navigation channels vs. alternative pathways in two multi-channel rivers differentially affected by channelization, but free of barriers to sturgeon movement. Acoustic telemetry was used to quantify Lake Sturgeon movements. Under the assumption that Lake Sturgeon navigate by following primary flow paths, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River were expected to choose navigation channels over alternative pathways and to exhibit greater selection for navigation channels than conspecifics in the less-channelized lower St. Clair River. Consistent with these predictions, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River selected the higher-flow and deeper navigation channels over alternative migration pathways, whereas in the less-channelized lower St. Clair River, individuals primarily used pathways alternative to navigation channels. Lake Sturgeon selection for navigation channels as migratory pathways also was significantly higher in the more-channelized lower Detroit River than in the less-channelized lower St. Clair River. We speculated that use of navigation channels over alternative pathways would increase the spatial overlap of commercial vessels and migrating Lake Sturgeon, potentially enhancing their vulnerability to ship strikes. Results of our study thus demonstrated an association between channelization and the path use of migrating Lake Sturgeon that could prove important for

  20. On parts and holes: the spatial structure of the human body.

    PubMed

    Donnelly, Maureen

    2004-01-01

    Spatial representation and reasoning is a central component of medical informatics. The spatial concepts most often used in medicine are not the quantitative, point-based concepts of classical geometry, but rather qualitative relations among extended objects such as body parts. A mereotopology is a formal theory of qualitative spatial relations, such as parthood and connection. This paper considers how an extension of mereotopology which includes also location relations can be used to represent and reason about the spatial structure of the human body.

  1. Rethinking human visual attention: spatial cueing effects and optimality of decisions by honeybees, monkeys and humans.

    PubMed

    Eckstein, Miguel P; Mack, Stephen C; Liston, Dorion B; Bogush, Lisa; Menzel, Randolf; Krauzlis, Richard J

    2013-06-07

    Visual attention is commonly studied by using visuo-spatial cues indicating probable locations of a target and assessing the effect of the validity of the cue on perceptual performance and its neural correlates. Here, we adapt a cueing task to measure spatial cueing effects on the decisions of honeybees and compare their behavior to that of humans and monkeys in a similarly structured two-alternative forced-choice perceptual task. Unlike the typical cueing paradigm in which the stimulus strength remains unchanged within a block of trials, for the monkey and human studies we randomized the contrast of the signal to simulate more real world conditions in which the organism is uncertain about the strength of the signal. A Bayesian ideal observer that weights sensory evidence from cued and uncued locations based on the cue validity to maximize overall performance is used as a benchmark of comparison against the three animals and other suboptimal models: probability matching, ignore the cue, always follow the cue, and an additive bias/single decision threshold model. We find that the cueing effect is pervasive across all three species but is smaller in size than that shown by the Bayesian ideal observer. Humans show a larger cueing effect than monkeys and bees show the smallest effect. The cueing effect and overall performance of the honeybees allows rejection of the models in which the bees are ignoring the cue, following the cue and disregarding stimuli to be discriminated, or adopting a probability matching strategy. Stimulus strength uncertainty also reduces the theoretically predicted variation in cueing effect with stimulus strength of an optimal Bayesian observer and diminishes the size of the cueing effect when stimulus strength is low. A more biologically plausible model that includes an additive bias to the sensory response from the cued location, although not mathematically equivalent to the optimal observer for the case stimulus strength uncertainty, can

  2. 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

  3. Spatial analysis on human brucellosis incidence in mainland China: 2004–2010

    PubMed Central

    Zhang, Junhui; Yin, Fei; Zhang, Tao; Yang, Chao; Zhang, Xingyu; Feng, Zijian; Li, Xiaosong

    2014-01-01

    Objectives China has experienced a sharply increasing rate of human brucellosis in recent years. Effective spatial monitoring of human brucellosis incidence is very important for successful implementation of control and prevention programmes. The purpose of this paper is to apply exploratory spatial data analysis (ESDA) methods and the empirical Bayes (EB) smoothing technique to monitor county-level incidence rates for human brucellosis in mainland China from 2004 to 2010 by examining spatial patterns. Methods ESDA methods were used to characterise spatial patterns of EB smoothed incidence rates for human brucellosis based on county-level data obtained from the China Information System for Disease Control and Prevention (CISDCP) in mainland China from 2004 to 2010. Results EB smoothed incidence rates for human brucellosis were spatially dependent during 2004–2010. The local Moran test identified significantly high-risk clusters of human brucellosis (all p values <0.01), which persisted during the 7-year study period. High-risk counties were centred in the Inner Mongolia Autonomous Region and other Northern provinces (ie, Hebei, Shanxi, Jilin and Heilongjiang provinces) around the border with the Inner Mongolia Autonomous Region where animal husbandry was highly developed. The number of high-risk counties increased from 25 in 2004 to 54 in 2010. Conclusions ESDA methods and the EB smoothing technique can assist public health officials in identifying high-risk areas. Allocating more resources to high-risk areas is an effective way to reduce human brucellosis incidence. PMID:24713215

  4. Comparison of Urban Human Movements Inferring from Multi-Source Spatial-Temporal Data

    NASA Astrophysics Data System (ADS)

    Cao, Rui; Tu, Wei; Cao, Jinzhou; Li, Qingquan

    2016-06-01

    The quantification of human movements is very hard because of the sparsity of traditional data and the labour intensive of the data collecting process. Recently, much spatial-temporal data give us an opportunity to observe human movement. This research investigates the relationship of city-wide human movements inferring from two types of spatial-temporal data at traffic analysis zone (TAZ) level. The first type of human movement is inferred from long-time smart card transaction data recording the boarding actions. The second type of human movement is extracted from citywide time sequenced mobile phone data with 30 minutes interval. Travel volume, travel distance and travel time are used to measure aggregated human movements in the city. To further examine the relationship between the two types of inferred movements, the linear correlation analysis is conducted on the hourly travel volume. The obtained results show that human movements inferred from smart card data and mobile phone data have a correlation of 0.635. However, there are still some non-ignorable differences in some special areas. This research not only reveals the citywide spatial-temporal human dynamic but also benefits the understanding of the reliability of the inference of human movements with big spatial-temporal data.

  5. Spatially Distributed Encoding of Covert Attentional Shifts in Human Thalamus

    PubMed Central

    Hulme, Oliver J.; Whiteley, Louise

    2010-01-01

    Spatial attention modulates signal processing within visual nuclei of the thalamus—but do other nuclei govern the locus of attention in top-down mode? We examined functional MRI (fMRI) data from three subjects performing a task requiring covert attention to 1 of 16 positions in a circular array. Target position was cued after stimulus offset, requiring subjects to perform target detection from iconic visual memory. We found positionally specific responses at multiple thalamic sites, with individual voxels activating at more than one direction of attentional shift. Voxel clusters at anatomically equivalent sites across subjects revealed a broad range of directional tuning at each site, with little sign of contralateral bias. By reference to a thalamic atlas, we identified the nuclear correspondence of the four most reliably activated sites across subjects: mediodorsal/central-intralaminar (oculomotor thalamus), caudal intralaminar/parafascicular, suprageniculate/limitans, and medial pulvinar/lateral posterior. Hence, the cortical network generating a top-down control signal for relocating attention acts in concert with a spatially selective thalamic apparatus—the set of active nuclei mirroring the thalamic territory of cortical “eye-field” areas, thus supporting theories which propose the visuomotor origins of covert attentional selection. PMID:20844113

  6. New bionic navigation algorithm based on the visual navigation mechanism of bees

    NASA Astrophysics Data System (ADS)

    Huang, Yufeng; Liu, Yi; Liu, Jianguo

    2015-04-01

    Through some research on visual navigation mechanisms of flying insects especially honeybees, a novel navigation algorithm integrating entropy flow with Kalman filter has been introduced in this paper. Concepts of entropy image and entropy flow are also introduced, which can characterize topographic features and measure changes of the image respectively. To characterize texture feature and spatial distribution of an image, a new concept of contrast entropy image has been presented in this paper. Applying the contrast entropy image to the navigation algorithm to test its' performance of navigation and comparing with simulation results of intensity entropy image, a conclusion that contrast entropy image performs better and more robust in navigation has been made.

  7. Viking navigation

    NASA Technical Reports Server (NTRS)

    Oneil, W. J.; Rudd, R. P.; Farless, D. L.; Hildebrand, C. E.; Mitchell, R. T.; Rourke, K. H.; Euler, E. A.

    1979-01-01

    A comprehensive description of the navigation of the Viking spacecraft throughout their flight from Earth launch to Mars landing is given. The flight path design, actual inflight control, and postflight reconstruction are discussed in detail. The preflight analyses upon which the operational strategies and performance predictions were based are discussed. The inflight results are then discussed and compared with the preflight predictions and, finally, the results of any postflight analyses are presented.

  8. Navigating from a Depth Image Converted into Sound

    PubMed Central

    Stoll, Chloé; Palluel-Germain, Richard; Fristot, Vincent; Pellerin, Denis; Alleysson, David; Graff, Christian

    2015-01-01

    Background. Common manufactured depth sensors generate depth images that humans normally obtain from their eyes and hands. Various designs converting spatial data into sound have been recently proposed, speculating on their applicability as sensory substitution devices (SSDs). Objective. We tested such a design as a travel aid in a navigation task. Methods. Our portable device (MeloSee) converted 2D array of a depth image into melody in real-time. Distance from the sensor was translated into sound intensity, stereo-modulated laterally, and the pitch represented verticality. Twenty-one blindfolded young adults navigated along four different paths during two sessions separated by one-week interval. In some instances, a dual task required them to recognize a temporal pattern applied through a tactile vibrator while they navigated. Results. Participants learnt how to use the system on both new paths and on those they had already navigated from. Based on travel time and errors, performance improved from one week to the next. The dual task was achieved successfully, slightly affecting but not preventing effective navigation. Conclusions. The use of Kinect-type sensors to implement SSDs is promising, but it is restricted to indoor use and it is inefficient on too short range. PMID:27019586

  9. The Navigation Guide—Evidence-Based Medicine Meets Environmental Health: Integration of Animal and Human Evidence for PFOA Effects on Fetal Growth

    PubMed Central

    Koustas, Erica; Sutton, Patrice; Johnson, Paula I.; Atchley, Dylan S.; Sen, Saunak; Robinson, Karen A.; Axelrad, Daniel A.; Woodruff, Tracey J.

    2014-01-01

    Background: The Navigation Guide is a novel systematic review method to synthesize scientific evidence and reach strength of evidence conclusions for environmental health decision making. Objective: Our aim was to integrate scientific findings from human and nonhuman studies to determine the overall strength of evidence for the question “Does developmental exposure to perfluorooctanoic acid (PFOA) affect fetal growth in humans?” Methods: We developed and applied prespecified criteria to systematically and transparently a) rate the quality of the scientific evidence as “high,” “moderate,” or “low”; b) rate the strength of the human and nonhuman evidence separately as “sufficient,” “limited,” “moderate,” or “evidence of lack of toxicity”; and c) integrate the strength of the human and nonhuman evidence ratings into a strength of the evidence conclusion. Results: We identified 18 epidemiology studies and 21 animal toxicology studies relevant to our study question. We rated both the human and nonhuman mammalian evidence as “moderate” quality and “sufficient” strength. Integration of these evidence ratings produced a final strength of evidence rating in which review authors concluded that PFOA is “known to be toxic” to human reproduction and development based on sufficient evidence of decreased fetal growth in both human and nonhuman mammalian species. Conclusion: We concluded that developmental exposure to PFOA adversely affects human health based on sufficient evidence of decreased fetal growth in both human and nonhuman mammalian species. The results of this case study demonstrate the application of a systematic and transparent methodology, via the Navigation Guide, for reaching strength of evidence conclusions in environmental health. Citation: Lam J, Koustas E, Sutton P, Johnson PI, Atchley DS, Sen S, Robinson KA, Axelrad DA, Woodruff TJ. 2014. The Navigation Guide—evidence-based medicine meets environmental health

  10. 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…

  11. 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…

  12. Spatial Effects of Sound on Visual Activity in Human Newborns.

    ERIC Educational Resources Information Center

    Mendelson, Morton J.; Haith, Marshall M.

    This study investigated the possibility of a functional relation between the auditory and visual systems in the human newborn beyond reflexive organization. Visual activity was monitored in 16 newborns through the use of infrared corneal reflection video tape recording. Infants were observed in total darkness and while monocularly viewing a…

  13. Human Timeline: A Spatial-Kinesthetic Exercise in Biblical History

    ERIC Educational Resources Information Center

    Wolfe, Lisa M.

    2009-01-01

    The Human Timeline invites students to physically re-create biblical history. Each student holds a card that denotes an event randomly selected from the biblical timeline. They then arrange themselves chronologically to learn the correct flow of biblical history. Because of the movement involved and the arbitrary layout of the cards among their…

  14. Interaction between Locale and Taxon Strategies in Human Spatial Learning

    ERIC Educational Resources Information Center

    Redhead, Edward S.; Hamilton, Derek A.

    2007-01-01

    Three computer-based experiments which tested human participants in a non-immersive virtual watermaze task sought to determine factors which dictate whether the presence of a visual platform disrupts locale learning and taxon learning. In Experiment 1, the visible platform disrupted locale but not taxon learning based on viewpoint-independent and…

  15. Human Timeline: A Spatial-Kinesthetic Exercise in Biblical History

    ERIC Educational Resources Information Center

    Wolfe, Lisa M.

    2009-01-01

    The Human Timeline invites students to physically re-create biblical history. Each student holds a card that denotes an event randomly selected from the biblical timeline. They then arrange themselves chronologically to learn the correct flow of biblical history. Because of the movement involved and the arbitrary layout of the cards among their…

  16. Incorporating Human Movement Behavior into the Analysis of Spatially Distributed Infrastructure

    PubMed Central

    Wu, Lihua; Leung, Henry; Jiang, Hao; Zheng, Hong; Ma, Li

    2016-01-01

    For the first time in human history, the majority of the world's population resides in urban areas. Therefore, city managers are faced with new challenges related to the efficiency, equity and quality of the supply of resources, such as water, food and energy. Infrastructure in a city can be viewed as service points providing resources. These service points function together as a spatially collaborative system to serve an increasing population. To study the spatial collaboration among service points, we propose a shared network according to human's collective movement and resource usage based on data usage detail records (UDRs) from the cellular network in a city in western China. This network is shown to be not scale-free, but exhibits an interesting triangular property governed by two types of nodes with very different link patterns. Surprisingly, this feature is consistent with the urban-rural dualistic context of the city. Another feature of the shared network is that it consists of several spatially separated communities that characterize local people's active zones but do not completely overlap with administrative areas. According to these features, we propose the incorporation of human movement into infrastructure classification. The presence of well-defined spatially separated clusters confirms the effectiveness of this approach. In this paper, our findings reveal the spatial structure inside a city, and the proposed approach provides a new perspective on integrating human movement into the study of a spatially distributed system. PMID:26784749

  17. City rats: insight from rat spatial behavior into human cognition in urban environments.

    PubMed

    Yaski, Osnat; Portugali, Juval; Eilam, David

    2011-09-01

    The structure and shape of the urban environment influence our ability to find our way about in the city. Understanding how the physical properties of the environment affect spatial behavior and cognition is therefore a necessity. However, there are inherent difficulties in empirically studying complex and large-scale urban environments. These include the need to isolate the impact of specific urban features and to acquire data on the physical activity of individuals. In the present study, we attempted to overcome the above obstacles and examine the relation between urban environments and spatial cognition by testing the spatial behavior of rats. This idea originated from the resemblance in the operative brain functions and in the mechanisms and strategies employed by humans and other animals when acquiring spatial information and establishing an internal representation, as revealed in past studies. Accordingly, we tested rats in arenas that simulated a grid urban layout (e.g. Manhattan streets) and an irregular urban layout (e.g. Jerusalem streets). We found that in the grid layout, rat movement was more structured and extended over a greater area compared with their restricted movement in the irregular layout. These movement patterns recall those of humans in respective urban environments, illustrating that the structure and shape of the environment affect spatial behavior similarly in humans and rats. Overall, testing rats in environments that simulate facets of urban environments can provide new insights into human spatial cognition in urban environments.

  18. Navigating to new frontiers in behavioral neuroscience: traditional neuropsychological tests predict human performance on a rodent-inspired radial-arm maze

    PubMed Central

    Mennenga, Sarah E.; Baxter, Leslie C.; Grunfeld, Itamar S.; Brewer, Gene A.; Aiken, Leona S.; Engler-Chiurazzi, Elizabeth B.; Camp, Bryan W.; Acosta, Jazmin I.; Braden, B. Blair; Schaefer, Keley R.; Gerson, Julia E.; Lavery, Courtney N.; Tsang, Candy W. S.; Hewitt, Lauren T.; Kingston, Melissa L.; Koebele, Stephanie V.; Patten, K. Jakob; Ball, B. Hunter; McBeath, Michael K.; Bimonte-Nelson, Heather A.

    2014-01-01

    We constructed an 11-arm, walk-through, human radial-arm maze (HRAM) as a translational instrument to compare existing methodology in the areas of rodent and human learning and memory research. The HRAM, utilized here, serves as an intermediary test between the classic rat radial-arm maze (RAM) and standard human neuropsychological and cognitive tests. We show that the HRAM is a useful instrument to examine working memory ability, explore the relationships between rodent and human memory and cognition models, and evaluate factors that contribute to human navigational ability. One-hundred-and-fifty-seven participants were tested on the HRAM, and scores were compared to performance on a standard cognitive battery focused on episodic memory, working memory capacity, and visuospatial ability. We found that errors on the HRAM increased as working memory demand became elevated, similar to the pattern typically seen in rodents, and that for this task, performance appears similar to Miller's classic description of a processing-inclusive human working memory capacity of 7 ± 2 items. Regression analysis revealed that measures of working memory capacity and visuospatial ability accounted for a large proportion of variance in HRAM scores, while measures of episodic memory and general intelligence did not serve as significant predictors of HRAM performance. We present the HRAM as a novel instrument for measuring navigational behavior in humans, as is traditionally done in basic science studies evaluating rodent learning and memory, thus providing a useful tool to help connect and translate between human and rodent models of cognitive functioning. PMID:25249951

  19. Spatial heterogeneity in human activities favors the persistence of wolves in agroecosystems.

    PubMed

    Ahmadi, Mohsen; López-Bao, José Vicente; Kaboli, Mohammad

    2014-01-01

    As human populations expand, there is increasing demand and pressure for land. Under this scenario, behavioural flexibility and adaptation become important processes leading to the persistence of large carnivores in human-dominated landscapes such as agroecosystems. A growing interest has recently emerged on the outcome of the coexistence between wolves and humans in these systems. It has been suggested that spatial heterogeneity in human activities would be a major environmental factor modulating vulnerability and persistence of this contentious species in agroecosystems. Here, we combined information from 35 den sites detected between 2011 and 2012 in agroecosystems of western Iran (Hamedan province), a set of environmental variables measured at landscape and fine spatial scales, and generalized linear models to identify patterns of den site selection by wolves in a highly-modified agroecosystem. On a landscape level, wolves selected a mixture of rangelands with scattered dry-farms on hillsides (showing a low human use) to locate their dens, avoiding areas with high densities of settlements and primary roads. On a fine spatial scale, wolves primarily excavated dens into the sides of elevated steep-slope hills with availability of water bodies in the vicinity of den sites, and wolves were relegated to dig in places with coarse-soil particles. Our results suggest that vulnerability of wolves in human-dominated landscapes could be compensated by the existence of spatial heterogeneity in human activities. Such heterogeneity would favor wolf persistence in agroecosystems favoring a land sharing model of coexistence between wolves and people.

  20. Spatial Heterogeneity in Human Activities Favors the Persistence of Wolves in Agroecosystems

    PubMed Central

    Ahmadi, Mohsen; López-Bao, José Vicente; Kaboli, Mohammad

    2014-01-01

    As human populations expand, there is increasing demand and pressure for land. Under this scenario, behavioural flexibility and adaptation become important processes leading to the persistence of large carnivores in human-dominated landscapes such as agroecosystems. A growing interest has recently emerged on the outcome of the coexistence between wolves and humans in these systems. It has been suggested that spatial heterogeneity in human activities would be a major environmental factor modulating vulnerability and persistence of this contentious species in agroecosystems. Here, we combined information from 35 den sites detected between 2011 and 2012 in agroecosystems of western Iran (Hamedan province), a set of environmental variables measured at landscape and fine spatial scales, and generalized linear models to identify patterns of den site selection by wolves in a highly-modified agroecosystem. On a landscape level, wolves selected a mixture of rangelands with scattered dry-farms on hillsides (showing a low human use) to locate their dens, avoiding areas with high densities of settlements and primary roads. On a fine spatial scale, wolves primarily excavated dens into the sides of elevated steep-slope hills with availability of water bodies in the vicinity of den sites, and wolves were relegated to dig in places with coarse-soil particles. Our results suggest that vulnerability of wolves in human-dominated landscapes could be compensated by the existence of spatial heterogeneity in human activities. Such heterogeneity would favor wolf persistence in agroecosystems favoring a land sharing model of coexistence between wolves and people. PMID:25251567

  1. Categories and Range Effects in Human Spatial Memory

    PubMed Central

    Cheng, Ken; Spetch, Marcia L.; Hoan, Andros

    2010-01-01

    After learning a particular target stimulus, such as a location, humans’ judgments of whether a particular stimulus is the target or not is affected by the range of stimuli presented on tests. In such frequently found range effects, the peak of “yes” responses shifts toward the middle of the range of tested stimuli. Humans also code both the metric value and categorical information regarding a target stimulus, and use both forms of codes, such that responses are biased toward the category middle (category adjustment model, Duffy et al., 2010). Categorical codes should also affect range effects, with a test range crossing category boundaries producing less range effect than a test range within a category. We examined a set of past results presented in a review of range effects in humans (Thomas, 1993) for functional explanations in light of categorical coding, and found that all results could be reasonably explained. Additional experiments comparing range effects across vs. within a category found limited supporting evidence, perhaps because the range effects were weak. The adaptive functions of using (in part) categorical coding accounts for many seemingly peculiar biases in human cognition. PMID:21833286

  2. Temporal and spatial distribution of human cryptosporidiosis in the west of Ireland 2004-2007

    PubMed Central

    2009-01-01

    Background Cryptosporidiosis is increasingly recognised as a cause of gastrointestinal infection in Ireland and has been implicated in several outbreaks. This study aimed to investigate the spatial and temporal distribution of human cryptosporidiosis in the west of Ireland in order to identify high risk seasons and areas and to compare Classically Calculated (CC) and Empirical Bayesian (EB) incidence rates. Two spatial scales of analysis were used with a view to identifying the best one in assessing geographical patterns of infection. Global Moran's I and Local Moran's I tests of autocorrelation were used to test for evidence of global and local spatial clustering. Results There were statistically significant seasonal patterns of cryptosporidiosis with peaks in spring and an increasing temporal trend. Significant (p < 0.05) global spatial clustering was observed in CC rates at the Electoral Division (ED) level but not in EB rates at the same level. Despite variations in disease, ED level was found to provide the most accurate account of distribution of cryptosporidiosis in the West of Ireland but required spatial EB smoothing of cases. There were a number of areas identified with significant local clustering of cryptosporidiosis rates. Conclusion This study identified spatial and temporal patterns in cryptosporidiosis distribution. The study also showed benefit in performing spatial analyses at more than one spatial scale to assess geographical patterns in disease distribution and that smoothing of disease rates for mapping in small areas enhances visualisation of spatial patterns. These findings are relevant in guiding policy decisions on disease control strategies. PMID:19930685

  3. Modeling Human Spatial Memory Within a Symbolic Architecture of Cognition

    NASA Astrophysics Data System (ADS)

    Winkelholz, Carsten; Schlick, Christopher M.

    This paper presents a study on the integration of spatial cognition into a symbolic theory. The concepts of encoding object-locations in local allocentric reference systems and noisy representations of locations have been integrated into the ACT-R architecture of cognition. The intrinsic reference axis of the local reference systems automatically result from the sequence of attended locations. The first part of the paper describes experiments we performed to test hypotheses on the usage of local allocentric reference systems in the context of object-location memory in graphical layout structures. The second part describes in more detail the theory and its integration into ACT-R. Based on the theory a model has been developed for the task in the experiments. The parameters for the noise in the representation of locations and the parameters for the recall of symbolic memory chunks were set to values in the magnitude quoted in literature. The model satisfyingly reproduces the data from user studies with 30 subjects.

  4. The Role of Users' Concepts of the Robot in Human-Robot Spatial Instruction

    NASA Astrophysics Data System (ADS)

    Fischer, Kerstin

    Spatial instructions are always delivered for a particular communication partner. In this paper I investigate the the role of users' concepts of their communication partner in human-robot interaction by analysing the spatial language choices speakers make in three comparable corpora with three different robots. I show that the users' concepts of their artificial communication partner is only mildly shaped by the appearance of the robot, and thus that users do not mindlessly use all clues they can get about their communication partner in order to formulate their spatial instructions. Instead, spatial instruction in human-robot interaction also depends on the users' models of the communication situation, as well as on external variables, such as gender.

  5. Modelling group navigation: transitive social structures improve navigational performance.

    PubMed

    Flack, Andrea; Biro, Dora; Guilford, Tim; Freeman, Robin

    2015-07-06

    Collective navigation demands that group members reach consensus on which path to follow, a task that might become more challenging when the group's members have different social connections. Group decision-making mechanisms have been studied successfully in the past using individual-based modelling, although many of these studies have neglected the role of social connections between the group's interacting members. Nevertheless, empirical studies have demonstrated that individual recognition, previous shared experiences and inter-individual familiarity can influence the cohesion and the dynamics of the group as well as the relative spatial positions of specific individuals within it. Here, we use models of collective motion to study the impact of social relationships on group navigation by introducing social network structures into a model of collective motion. Our results show that groups consisting of equally informed individuals achieve the highest level of accuracy when they are hierarchically organized with the minimum number of preferred connections per individual. We also observe that the navigational accuracy of a group will depend strongly on detailed aspects of its social organization. More specifically, group navigation does not only depend on the underlying social relationships, but also on how much weight leading individuals put on following others. Also, we show that groups with certain social structures can compensate better for an increased level of navigational error. The results have broader implications for studies on collective navigation and motion because they show that only by considering a group's social system can we fully elucidate the dynamics and advantages of joint movements.

  6. A Formal Investigation of Human Spatial Control Skills: Mathematical Formalization, Skill Development, and Skill Assessment

    NASA Astrophysics Data System (ADS)

    Li, Bin

    Spatial control behaviors account for a large proportion of human everyday activities from normal daily tasks, such as reaching for objects, to specialized tasks, such as driving, surgery, or operating equipment. These behaviors involve intensive interactions within internal processes (i.e. cognitive, perceptual, and motor control) and with the physical world. This dissertation builds on a concept of interaction pattern and a hierarchical functional model. Interaction pattern represents a type of behavior synergy that humans coordinates cognitive, perceptual, and motor control processes. It contributes to the construction of the hierarchical functional model that delineates humans spatial control behaviors as the coordination of three functional subsystems: planning, guidance, and tracking/pursuit. This dissertation formalizes and validates these two theories and extends them for the investigation of human spatial control skills encompassing development and assessment. Specifically, this dissertation first presents an overview of studies in human spatial control skills encompassing definition, characteristic, development, and assessment, to provide theoretical evidence for the concept of interaction pattern and the hierarchical functional model. The following, the human experiments for collecting motion and gaze data and techniques to register and classify gaze data, are described. This dissertation then elaborates and mathematically formalizes the hierarchical functional model and the concept of interaction pattern. These theories then enables the construction of a succinct simulation model that can reproduce a variety of human performance with a minimal set of hypotheses. This validates the hierarchical functional model as a normative framework for interpreting human spatial control behaviors. The dissertation then investigates human skill development and captures the emergence of interaction pattern. The final part of the dissertation applies the hierarchical

  7. As the world turns: short-term human spatial memory in egocentric and allocentric coordinates.

    PubMed

    Banta Lavenex, Pamela; Lecci, Sandro; Prêtre, Vincent; Brandner, Catherine; Mazza, Christian; Pasquier, Jérôme; Lavenex, Pierre

    2011-05-16

    We aimed to determine whether human subjects' reliance on different sources of spatial information encoded in different frames of reference (i.e., egocentric versus allocentric) affects their performance, decision time and memory capacity in a short-term spatial memory task performed in the real world. Subjects were asked to play the Memory game (a.k.a. the Concentration game) without an opponent, in four different conditions that controlled for the subjects' reliance on egocentric and/or allocentric frames of reference for the elaboration of a spatial representation of the image locations enabling maximal efficiency. We report experimental data from young adult men and women, and describe a mathematical model to estimate human short-term spatial memory capacity. We found that short-term spatial memory capacity was greatest when an egocentric spatial frame of reference enabled subjects to encode and remember the image locations. However, when egocentric information was not reliable, short-term spatial memory capacity was greater and decision time shorter when an allocentric representation of the image locations with respect to distant objects in the surrounding environment was available, as compared to when only a spatial representation encoding the relationships between the individual images, independent of the surrounding environment, was available. Our findings thus further demonstrate that changes in viewpoint produced by the movement of images placed in front of a stationary subject is not equivalent to the movement of the subject around stationary images. We discuss possible limitations of classical neuropsychological and virtual reality experiments of spatial memory, which typically restrict the sensory information normally available to human subjects in the real world.

  8. Inflammatory signaling in human Tuberculosis granulomas is spatially organized

    PubMed Central

    Marakalala, Mohlopheni J.; Raju, Ravikiran M.; Sharma, Kirti; Zhang, Yanjia J.; Eugenin, Eliseo A.; Prideaux, Brendan; Daudelin, Isaac B.; Chen, Pei-Yu; Booty, Matthew G.; Kim, Jin Hee; Eum, Seok Yong; Via, Laura E.; Behar, Samuel M.; Barry, Clifton E.; Mann, Matthias; Dartois, Véronique; Rubin, Eric J.

    2016-01-01

    Granulomas are the pathological hallmark of tuberculosis (TB). However, their function and mechanisms of formation remain poorly understood. To understand the role of granulomas in TB, we analyzed the proteomes of granulomas from subjects with tuberculosis in an unbiased fashion. Using laser capture microdissection, mass spectrometry and confocal microscopy, we generated detailed molecular maps of human granulomas. We found that the centers of granulomas possess a pro-inflammatory environment characterized by anti-microbial peptides, ROS and pro-inflammatory eicosanoids. Conversely, the tissue surrounding the caseum possesses a comparatively anti-inflammatory signature. These findings are consistent across a set of six subjects and in rabbits. While the balance between systemic pro- and anti-inflammatory signals is crucial to TB disease outcome, here we find that these signals are physically segregated within each granuloma. The protein and lipid snapshots of human and rabbit lesions analysed here suggest that the pathologic response to TB is shaped by the precise anatomical localization of these inflammatory pathways during the development of the granuloma. PMID:27043495

  9. Topographic Maps of Visual Spatial Attention in Human Parietal Cortex

    PubMed Central

    Silver, Michael A.; Ress, David; Heeger, David J.

    2008-01-01

    Functional magnetic resonance imaging (fMRI) was used to measure activity in human parietal cortex during performance of a visual detection task in which the focus of attention systematically traversed the visual field. Critically, the stimuli were identical on all trials (except for slight contrast changes in a fully randomized selection of the target locations) whereas only the cued location varied. Traveling waves of activity were observed in posterior parietal cortex consistent with shifts in covert attention in the absence of eye movements. The temporal phase of the fMRI signal in each voxel indicated the corresponding visual field location. Visualization of the distribution of temporal phases on a flattened representation of parietal cortex revealed at least two distinct topographically organized cortical areas within the intraparietal sulcus (IPS), each representing the contralateral visual field. Two cortical areas were proposed based on this topographic organization, which we refer to as IPS1 and IPS2 to indicate their locations within the IPS. This nomenclature is neutral with respect to possible homologies with well-established cortical areas in the monkey brain. The two proposed cortical areas exhibited relatively little response to passive visual stimulation in comparison with early visual areas. These results provide evidence for multiple topographic maps in human parietal cortex. PMID:15817643

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

    PubMed

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

    2015-11-01

    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.

  11. 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

  12. Navigable networks as Nash equilibria of navigation games

    PubMed Central

    Gulyás, András; Bíró, József J.; Kőrösi, Attila; Rétvári, Gábor; Krioukov, Dmitri

    2015-01-01

    Common sense suggests that networks are not random mazes of purposeless connections, but that these connections are organized so that networks can perform their functions well. One function common to many networks is targeted transport or navigation. Here, using game theory, we show that minimalistic networks designed to maximize the navigation efficiency at minimal cost share basic structural properties with real networks. These idealistic networks are Nash equilibria of a network construction game whose purpose is to find an optimal trade-off between the network cost and navigability. We show that these skeletons are present in the Internet, metabolic, English word, US airport, Hungarian road networks, and in a structural network of the human brain. The knowledge of these skeletons allows one to identify the minimal number of edges, by altering which one can efficiently improve or paralyse navigation in the network. PMID:26138277

  13. Navigable networks as Nash equilibria of navigation games

    NASA Astrophysics Data System (ADS)

    Gulyás, András; Bíró, József J.; Kőrösi, Attila; Rétvári, Gábor; Krioukov, Dmitri

    2015-07-01

    Common sense suggests that networks are not random mazes of purposeless connections, but that these connections are organized so that networks can perform their functions well. One function common to many networks is targeted transport or navigation. Here, using game theory, we show that minimalistic networks designed to maximize the navigation efficiency at minimal cost share basic structural properties with real networks. These idealistic networks are Nash equilibria of a network construction game whose purpose is to find an optimal trade-off between the network cost and navigability. We show that these skeletons are present in the Internet, metabolic, English word, US airport, Hungarian road networks, and in a structural network of the human brain. The knowledge of these skeletons allows one to identify the minimal number of edges, by altering which one can efficiently improve or paralyse navigation in the network.

  14. Navigable networks as Nash equilibria of navigation games.

    PubMed

    Gulyás, András; Bíró, József J; Kőrösi, Attila; Rétvári, Gábor; Krioukov, Dmitri

    2015-07-03

    Common sense suggests that networks are not random mazes of purposeless connections, but that these connections are organized so that networks can perform their functions well. One function common to many networks is targeted transport or navigation. Here, using game theory, we show that minimalistic networks designed to maximize the navigation efficiency at minimal cost share basic structural properties with real networks. These idealistic networks are Nash equilibria of a network construction game whose purpose is to find an optimal trade-off between the network cost and navigability. We show that these skeletons are present in the Internet, metabolic, English word, US airport, Hungarian road networks, and in a structural network of the human brain. The knowledge of these skeletons allows one to identify the minimal number of edges, by altering which one can efficiently improve or paralyse navigation in the network.

  15. Peripheral inflammation acutely impairs human spatial memory via actions on medial temporal lobe glucose metabolism.

    PubMed

    Harrison, Neil A; Doeller, Christian F; Voon, Valerie; Burgess, Neil; Critchley, Hugo D

    2014-10-01

    Inflammation impairs cognitive performance and is implicated in the progression of neurodegenerative disorders. Rodent studies demonstrated key roles for inflammatory mediators in many processes critical to memory, including long-term potentiation, synaptic plasticity, and neurogenesis. They also demonstrated functional impairment of medial temporal lobe (MTL) structures by systemic inflammation. However, human data to support this position are limited. Sequential fluorodeoxyglucose positron emission tomography together with experimentally induced inflammation was used to investigate effects of a systemic inflammatory challenge on human MTL function. Fluorodeoxyglucose positron emission tomography scanning was performed in 20 healthy participants before and after typhoid vaccination and saline control injection. After each scanning session, participants performed a virtual reality spatial memory task analogous to the Morris water maze and a mirror-tracing procedural memory control task. Fluorodeoxyglucose positron emission tomography data demonstrated an acute reduction in human MTL glucose metabolism after inflammation. The inflammatory challenge also selectively compromised human spatial, but not procedural, memory; this effect that was independent of actions on motivation or psychomotor response. Effects of inflammation on parahippocampal and rhinal glucose metabolism directly mediated actions of inflammation on spatial memory. These data demonstrate acute sensitivity of human MTL to mild peripheral inflammation, giving rise to associated functional impairment in the form of reduced spatial memory performance. Our findings suggest a mechanism for the observed epidemiologic link between inflammation and risk of age-related cognitive decline and progression of neurodegenerative disorders including Alzheimer's disease. Copyright © 2014 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  16. Temporal and spatial variation of the human microbiota during pregnancy

    PubMed Central

    DiGiulio, Daniel B.; Callahan, Benjamin J.; McMurdie, Paul J.; Costello, Elizabeth K.; Lyell, Deirdre J.; Robaczewska, Anna; Sun, Christine L.; Goltsman, Daniela S. A.; Wong, Ronald J.; Shaw, Gary; Stevenson, David K.; Holmes, Susan P.; Relman, David A.

    2015-01-01

    Despite the critical role of the human microbiota in health, our understanding of microbiota compositional dynamics during and after pregnancy is incomplete. We conducted a case-control study of 49 pregnant women, 15 of whom delivered preterm. From 40 of these women, we analyzed bacterial taxonomic composition of 3,767 specimens collected prospectively and weekly during gestation and monthly after delivery from the vagina, distal gut, saliva, and tooth/gum. Linear mixed-effects modeling, medoid-based clustering, and Markov chain modeling were used to analyze community temporal trends, community structure, and vaginal community state transitions. Microbiota community taxonomic composition and diversity remained remarkably stable at all four body sites during pregnancy (P > 0.05 for trends over time). Prevalence of a Lactobacillus-poor vaginal community state type (CST 4) was inversely correlated with gestational age at delivery (P = 0.0039). Risk for preterm birth was more pronounced for subjects with CST 4 accompanied by elevated Gardnerella or Ureaplasma abundances. This finding was validated with a set of 246 vaginal specimens from nine women (four of whom delivered preterm). Most women experienced a postdelivery disturbance in the vaginal community characterized by a decrease in Lactobacillus species and an increase in diverse anaerobes such as Peptoniphilus, Prevotella, and Anaerococcus species. This disturbance was unrelated to gestational age at delivery and persisted for up to 1 y. These findings have important implications for predicting premature labor, a major global health problem, and for understanding the potential impact of a persistent, altered postpartum microbiota on maternal health, including outcomes of pregnancies following short interpregnancy intervals. PMID:26283357

  17. Temporal and spatial variation of the human microbiota during pregnancy.

    PubMed

    DiGiulio, Daniel B; Callahan, Benjamin J; McMurdie, Paul J; Costello, Elizabeth K; Lyell, Deirdre J; Robaczewska, Anna; Sun, Christine L; Goltsman, Daniela S A; Wong, Ronald J; Shaw, Gary; Stevenson, David K; Holmes, Susan P; Relman, David A

    2015-09-01

    Despite the critical role of the human microbiota in health, our understanding of microbiota compositional dynamics during and after pregnancy is incomplete. We conducted a case-control study of 49 pregnant women, 15 of whom delivered preterm. From 40 of these women, we analyzed bacterial taxonomic composition of 3,767 specimens collected prospectively and weekly during gestation and monthly after delivery from the vagina, distal gut, saliva, and tooth/gum. Linear mixed-effects modeling, medoid-based clustering, and Markov chain modeling were used to analyze community temporal trends, community structure, and vaginal community state transitions. Microbiota community taxonomic composition and diversity remained remarkably stable at all four body sites during pregnancy (P > 0.05 for trends over time). Prevalence of a Lactobacillus-poor vaginal community state type (CST 4) was inversely correlated with gestational age at delivery (P = 0.0039). Risk for preterm birth was more pronounced for subjects with CST 4 accompanied by elevated Gardnerella or Ureaplasma abundances. This finding was validated with a set of 246 vaginal specimens from nine women (four of whom delivered preterm). Most women experienced a postdelivery disturbance in the vaginal community characterized by a decrease in Lactobacillus species and an increase in diverse anaerobes such as Peptoniphilus, Prevotella, and Anaerococcus species. This disturbance was unrelated to gestational age at delivery and persisted for up to 1 y. These findings have important implications for predicting premature labor, a major global health problem, and for understanding the potential impact of a persistent, altered postpartum microbiota on maternal health, including outcomes of pregnancies following short interpregnancy intervals.

  18. Assessing Spatial Learning and Memory in Rodents

    PubMed Central

    Vorhees, Charles V.; Williams, Michael T.

    2014-01-01

    Maneuvering safely through the environment is central to survival of almost all species. The ability to do this depends on learning and remembering locations. This capacity is encoded in the brain by two systems: one using cues outside the organism (distal cues), allocentric navigation, and one using self-movement, internal cues and nearby proximal cues, egocentric navigation. Allocentric navigation involves the hippocampus, entorhinal cortex, and surrounding structures; in humans this system encodes allocentric, semantic, and episodic memory. This form of memory is assessed in laboratory animals in many ways, but the dominant form of assessment is the Morris water maze (MWM). Egocentric navigation involves the dorsal striatum and connected structures; in humans this system encodes routes and integrated paths and, when overlearned, becomes procedural memory. In this article, several allocentric assessment methods for rodents are reviewed and compared with the MWM. MWM advantages (little training required, no food deprivation, ease of testing, rapid and reliable learning, insensitivity to differences in body weight and appetite, absence of nonperformers, control methods for proximal cue learning, and performance effects) and disadvantages (concern about stress, perhaps not as sensitive for working memory) are discussed. Evidence-based design improvements and testing methods are reviewed for both rats and mice. Experimental factors that apply generally to spatial navigation and to MWM specifically are considered. It is concluded that, on balance, the MWM has more advantages than disadvantages and compares favorably with other allocentric navigation tasks. PMID:25225309

  19. Spontaneous fast gamma activity in the septal hippocampal region correlates with spatial learning in humans.

    PubMed

    Cornwell, B R; Overstreet, C; Grillon, C

    2014-03-15

    Hippocampal neuronal populations exhibit multiple kinds of activity patterns, from the dominant theta rhythm during active exploration to high-frequency ripple-like activity during periods of relative inactivity. In animals, evidence is rapidly accruing that these high-frequency ripple activity patterns subserve retention of spatial learning performance. In a translational effort to address the possible function of offline hippocampal processes in humans, we measured spontaneous gamma activity during an awake rest period within a virtual spatial learning context. Whole-head magnetoencephalographic (MEG) recordings were taken while healthy participants (N=24) quietly rested (eyes open) between encoding and retrieval phases of a hippocampal-dependent virtual Morris water maze task. Results are that fast gamma activity (80-140 Hz) in the septal or posterior region of the hippocampus (bilaterally) was positively correlated across participants with subsequent within-session spatial learning rate. Fast gamma did not predict initial retrieval performance following rest, failing to provide evidence of a direct link between spontaneous high-frequency activity patterns during awake rest and consolidation of previous spatial memories. The findings nevertheless are consistent with a prospective role for offline human hippocampal processes in spatial learning and indicate that higher spontaneous gamma activity in the septal hippocampal region is related to faster updating of spatial knowledge in familiar virtual surroundings. Published by Elsevier B.V.

  20. Independent effects of motivation and spatial attention in the human visual cortex.

    PubMed

    Bayer, Mareike; Rossi, Valentina; Vanlessen, Naomi; Grass, Annika; Schacht, Annekathrin; Pourtois, Gilles

    2017-01-01

    Motivation and attention constitute major determinants of human perception and action. Nonetheless, it remains a matter of debate whether motivation effects on the visual cortex depend on the spatial attention system, or rely on independent pathways. This study investigated the impact of motivation and spatial attention on the activity of the human primary and extrastriate visual cortex by employing a factorial manipulation of the two factors in a cued pattern discrimination task. During stimulus presentation, we recorded event-related potentials and pupillary responses. Motivational relevance increased the amplitudes of the C1 component at ∼70 ms after stimulus onset. This modulation occurred independently of spatial attention effects, which were evident at the P1 level. Furthermore, motivation and spatial attention had independent effects on preparatory activation as measured by the contingent negative variation; and pupil data showed increased activation in response to incentive targets. Taken together, these findings suggest independent pathways for the influence of motivation and spatial attention on the activity of the human visual cortex.

  1. Spatial-temporal transcriptional dynamics of long non-coding RNAs in human brain.

    PubMed

    Zhang, Xiao-Qin; Wang, Ze-Lin; Poon, Ming-Wai; Yang, Jian-Hua

    2017-08-15

    The functional architecture of the human brain is greatly determined by the temporal and spatial regulation of the transcription process. However, the spatial and temporal transcriptional landscape of long non-coding RNAs (lncRNAs) during human brain development remains poorly understood. Here, we report the genome-wide lncRNA transcriptional analysis in an extensive series of 1340 post-mortem human brain specimens collected from 16 regions spanning the period from early embryo development to late adulthood. We discovered that lncRNA transcriptome dramatically changed during fetal development, while transited to a surprisingly relatively stable state after birth till the late adulthood. We also discovered that the transcription map of lncRNAs was spatially different, and that this spatial difference was developmentally regulated. Of the 16 brain regions explored (cerebellar cortex, thalamus, striatum, amygdala, hippocampus and 11 neocortex areas), cerebellar cortex showed the most distinct lncRNA expression features from all remaining brain regions throughout the whole developmental period, reflecting its unique developmental and functional features. Furthermore, by characterizing the functional modules and cellular processes of the spatial-temporal dynamic lncRNAs, we found that they were significantly associated with the RNA processing, neuron differentiation and synaptic signal transportation processes. Furthermore, we found that many lncRNAs associated with the neurodegenerative Alzheimer and Parkinson diseases were co-expressed in the fetal development of the human brain, and affected the convergent biological processes. In summary, our study provides a comprehensive map for lncRNA transcription dynamics in human brain development, which might shed light on the understanding of the molecular underpinnings of human brain function and disease. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. Does sex matter? Temporal and spatial patterns of cougar-human conflict in British Columbia.

    PubMed

    Teichman, Kristine J; Cristescu, Bogdan; Nielsen, Scott E

    2013-01-01

    Wildlife-human conflicts occur wherever large carnivores overlap human inhabited areas. Conflict mitigation can be facilitated by understanding long-term dynamics and examining sex-structured conflict patterns. Predicting areas with high probability of conflict helps focus management strategies in order to proactively decrease carnivore mortality. We investigated the importance of cougar (Puma concolor) habitat, human landscape characteristics and the combination of habitat and human features on the temporal and spatial patterns of cougar-human conflicts in British Columbia. Conflicts (n = 1,727; 1978-2007) involved similar numbers of male and female cougars with conflict rate decreasing over the past decade. Conflicts were concentrated within the southern part of the province with the most conflicts per unit area occurring on Vancouver Island. For both sexes, the most supported spatial models for the most recent (1998-2007) conflicts contained both human and habitat variables. Conflicts were more likely to occur close to roads, at intermediate elevations and far from the northern edge of the cougar distribution range in British Columbia. Male cougar conflicts were more likely to occur in areas of intermediate human density. Unlike cougar conflicts in other regions, cattle density was not a significant predictor of conflict location. With human populations expanding, conflicts are expected to increase. Conservation tools, such as the maps predicting conflict hotspots from this study, can help focus management efforts to decrease carnivore-human conflict.

  3. Does Sex Matter? Temporal and Spatial Patterns of Cougar-Human Conflict in British Columbia

    PubMed Central

    Teichman, Kristine J.; Cristescu, Bogdan; Nielsen, Scott E.

    2013-01-01

    Wildlife-human conflicts occur wherever large carnivores overlap human inhabited areas. Conflict mitigation can be facilitated by understanding long-term dynamics and examining sex-structured conflict patterns. Predicting areas with high probability of conflict helps focus management strategies in order to proactively decrease carnivore mortality. We investigated the importance of cougar (Puma concolor) habitat, human landscape characteristics and the combination of habitat and human features on the temporal and spatial patterns of cougar-human conflicts in British Columbia. Conflicts (n = 1,727; 1978–2007) involved similar numbers of male and female cougars with conflict rate decreasing over the past decade. Conflicts were concentrated within the southern part of the province with the most conflicts per unit area occurring on Vancouver Island. For both sexes, the most supported spatial models for the most recent (1998–2007) conflicts contained both human and habitat variables. Conflicts were more likely to occur close to roads, at intermediate elevations and far from the northern edge of the cougar distribution range in British Columbia. Male cougar conflicts were more likely to occur in areas of intermediate human density. Unlike cougar conflicts in other regions, cattle density was not a significant predictor of conflict location. With human populations expanding, conflicts are expected to increase. Conservation tools, such as the maps predicting conflict hotspots from this study, can help focus management efforts to decrease carnivore-human conflict. PMID:24040312

  4. Spatial Attention Changes Excitability of Human Visual Cortex to Direct Stimulation

    PubMed Central

    Bestmann, Sven; Ruff, Christian C.; Blakemore, Colin; Driver, Jon; Thilo, Kai V.

    2007-01-01

    Summary Conscious perception depends not only on sensory input, but also on attention [1, 2]. Recent studies in monkeys [3–6] and humans [7–12] suggest that influences of spatial attention on visual awareness may reflect top-down influences on excitability of visual cortex. Here we tested this specifically, by providing direct input into human visual cortex via cortical transcranial magnetic stimulation (TMS) to produce illusory visual percepts, called phosphenes. We found that a lower TMS intensity was needed to elicit a conscious phosphene when its apparent spatial location was attended, rather than unattended. Our results indicate that spatial attention can enhance visual-cortex excitability, and visual awareness, even when sensory signals from the eye via the thalamic pathway are bypassed. PMID:17240338

  5. Spatial attention changes excitability of human visual cortex to direct stimulation.

    PubMed

    Bestmann, Sven; Ruff, Christian C; Blakemore, Colin; Driver, Jon; Thilo, Kai V

    2007-01-23

    Conscious perception depends not only on sensory input, but also on attention [1, 2]. Recent studies in monkeys [3-6] and humans [7-12] suggest that influences of spatial attention on visual awareness may reflect top-down influences on excitability of visual cortex. Here we tested this specifically, by providing direct input into human visual cortex via cortical transcranial magnetic stimulation (TMS) to produce illusory visual percepts, called phosphenes. We found that a lower TMS intensity was needed to elicit a conscious phosphene when its apparent spatial location was attended, rather than unattended. Our results indicate that spatial attention can enhance visual-cortex excitability, and visual awareness, even when sensory signals from the eye via the thalamic pathway are bypassed.

  6. Spatial versus object feature processing in human auditory cortex: a magnetoencephalographic study.

    PubMed

    Herrmann, Christoph S; Senkowski, Daniel; Maess, Burkhard; Friederici, Angela D

    2002-12-06

    The human visual system is divided into two pathways specialized for the processing of either objects or spatial locations. Neuroanatomical studies in monkeys have suggested that a similar specialization may also divide auditory cortex into two such pathways. We used the identical stimulus material in two experimental sessions in which subjects had to either identify auditory objects or their location. Magnetoencephalograms were recorded and M100 dipoles were fitted into individual brain models. In the right hemisphere, the processing of auditory spatial information lead to more lateral activations within the temporal plane while object identification lead to more medial activations. These findings suggest that the human auditory system processes object features and spatial features in distinct areas.

  7. Spatial cluster analysis of human cases of Crimean Congo hemorrhagic fever reported in Pakistan.

    PubMed

    Abbas, Tariq; Younus, Muhammad; Muhammad, Sayyad Aun

    2015-01-01

    Crimean Congo hemorrhagic fever (CCHF) is a tick-borne viral zoonotic disease that has been reported in almost all geographic regions in Pakistan. The aim of this study was to identify spatial clusters of human cases of CCHF reported in country. Kulldorff's spatial scan statisitc, Anselin's Local Moran's I and Getis Ord Gi* tests were applied on data (i.e. number of laboratory confirmed cases reported from each district during year 2013). The analyses revealed a large multi-district cluster of high CCHF incidence in the uplands of Balochistan province near it border with Afghanistan. The cluster comprised the following districts: Qilla Abdullah; Qilla Saifullah; Loralai, Quetta, Sibi, Chagai, and Mastung. Another cluster was detected in Punjab and included Rawalpindi district and a part of Islamabad. We provide empirical evidence of spatial clustering of human CCHF cases in the country. The districts in the clusters should be given priority in surveillance, control programs, and further research.

  8. Applying Spatial Audio to Human Interfaces: 25 Years of NASA Experience

    NASA Technical Reports Server (NTRS)

    Begault, Durand R.; Wenzel, Elizabeth M.; Godfrey, Martine; Miller, Joel D.; Anderson, Mark R.

    2010-01-01

    From the perspective of human factors engineering, the inclusion of spatial audio within a human-machine interface is advantageous from several perspectives. Demonstrated benefits include the ability to monitor multiple streams of speech and non-speech warning tones using a cocktail party advantage, and for aurally-guided visual search. Other potential benefits include the spatial coordination and interaction of multimodal events, and evaluation of new communication technologies and alerting systems using virtual simulation. Many of these technologies were developed at NASA Ames Research Center, beginning in 1985. This paper reviews examples and describes the advantages of spatial sound in NASA-related technologies, including space operations, aeronautics, and search and rescue. The work has involved hardware and software development as well as basic and applied research.

  9. Mental transformations of spatial stimuli in humans and in monkeys: rotation vs. translocation.

    PubMed

    Nekovarova, Tereza; Nedvidek, Jan; Klement, Daniel; Rokyta, Richard; Bures, Jan

    2013-03-01

    We studied the ability of monkeys and humans to orient in one spatial frame ("response frame") according to abstract spatial stimuli presented in another spatial frame ("stimulus frame"). The stimuli were designed as simple maps of the "response space". We studied how the transformations of these stimuli affected the performance. The subjects were trained to choose a particular position in the response frame - either on a touch screen (monkeys) or on a keyboard (humans) - according to schematic spatial stimuli presented on the stimulus screen. The monkeys responded by touching one of four circles shown in corners of a rectangle displayed on the touch screen. The correct position was signaled by the stimulus ("map") presented on the stimulus screen. The map was a complementary rectangle, but only with one circle shown ("pointer"). The position of this circle indicated the correct position in the response frame. In the first experiment we only manipulated stimuli presented on the computer screen. The "map" was originally shown in the same position and orientation as the "response pattern" but later the position and the rotation of the map on the screen were changing. Such transformations of the stimuli allow us to study the mental operations that the animals performed and how particular mental transformations mutually differed. In the second experiment we tested whether the monkeys relied more on stimuli presented on the screen or on the surrounding stable environment and objects. We compared the performance of animals in tasks with rotated virtual maps in a stable surrounding environment with the performance in tasks where we rotated the surrounding frame (computer monitor), whereas the stimuli on the screen remained stable. In the third experiment we tested human subjects in analogous tests to compare the ability and cognitive strategies of monkeys and humans in this task. We showed that the mental strategies that monkeys used for orientation in one spatial frame

  10. Temporally and spatially partitioned behaviours of spinner dolphins: implications for resilience to human disturbance

    PubMed Central

    Johnston, David W.; Christiansen, Fredrik

    2017-01-01

    Selective forces shape the evolution of wildlife behavioural strategies and influence the spatial and temporal partitioning of behavioural activities to maximize individual fitness. Globally, wildlife is increasingly exposed to human activities which may affect their behavioural activities. The ability of wildlife to compensate for the effects of human activities may have implications for their resilience to disturbance. Resilience theory suggests that behavioural systems which are constrained in their repertoires are less resilient to disturbance than flexible systems. Using behavioural time-series data, we show that spinner dolphins (Stenella longirostris) spatially and temporally partition their behavioural activities on a daily basis. Specifically, spinner dolphins were never observed foraging during daytime, where resting was the predominant activity. Travelling and socializing probabilities were higher in early mornings and late afternoons when dolphins were returning from or preparing for nocturnal feeding trips, respectively. The constrained nature of spinner dolphin behaviours suggests they are less resilient to human disturbance than other cetaceans. These dolphins experience the highest exposure rates to human activities ever reported for any cetaceans. Over the last 30 years human activities have increased significantly in Hawaii, but the spinner dolphins still inhabit these bays. Recent abundance estimates (2011 and 2012) however, are lower than all previous estimates (1979–1981, 1989–1992 and 2003), indicating a possible long-term impact. Quantification of the spatial and temporal partitioning of wildlife behavioural schedules provides critical insight for conservation measures that aim to mitigate the effects of human disturbance. PMID:28280561

  11. Individual Differences in Spatial Pattern Separation Performance Associated with Healthy Aging in Humans

    ERIC Educational Resources Information Center

    Stark, Shauna M.; Yassa, Michael A.; Stark, Craig E. L.

    2010-01-01

    Rodent studies have suggested that "pattern separation," the ability to distinguish among similar experiences, is diminished in a subset of aged rats. We extended these findings to the human using a task designed to assess spatial pattern separation behavior (determining at time of test whether pairs of pictures shown during the study were in the…

  12. Individual Differences in Spatial Pattern Separation Performance Associated with Healthy Aging in Humans

    ERIC Educational Resources Information Center

    Stark, Shauna M.; Yassa, Michael A.; Stark, Craig E. L.

    2010-01-01

    Rodent studies have suggested that "pattern separation," the ability to distinguish among similar experiences, is diminished in a subset of aged rats. We extended these findings to the human using a task designed to assess spatial pattern separation behavior (determining at time of test whether pairs of pictures shown during the study were in the…

  13. Representing uncertainty in a spatial invasion model that incorporates human-mediated dispersal

    Treesearch

    Frank H. Koch; Denys Yemshanov; Robert A. Haack

    2013-01-01

    Most modes of human-mediated dispersal of invasive species are directional and vector-based. Classical spatial spread models usually depend on probabilistic dispersal kernels that emphasize distance over direction and have limited ability to depict rare but influential long-distance dispersal events. These aspects are problematic if such models are used to estimate...

  14. Human influence on the spatial structure of threatened Pacific salmon metapopulations

    Treesearch

    Aimee H. Fullerton; Steven T. Lindley; George R. Pess; Blake E. Feist; E. Ashley Steel; Paul. McElhany

    2011-01-01

    To remain viable, populations must be resilient to both natural and human-caused environmental changes. We evaluated anthropogenic effects on spatial connections among populations of Chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss) (designated as threatened under the U.S. Endangered Species Act) in the lower...

  15. Comparing the effect of humanoid and human face for the spatial orientation of attention

    PubMed Central

    Chaminade, Thierry; Okka, Maria M.

    2013-01-01

    The current study was designed to investigate how the automatic spatial orientation of attention induced by the perception of another agent's orientation of attention is modulated by the social nature of the other agent. Modified versions of the Posner task, using a real or schematic face with eyes or head looking toward the left or the right before a to-be-detected target appears on one side of the screen have been used to demonstrate a reduction of reaction time (RT) for target detection when the gaze is directed toward the target, even though the cue is not informative. We compared the effect of two agents, the humanoid robotic platform Nao and a real human, using head turn to cue the spatial orientation of attention. Our results reproduced the typical Posner effect, with reduced RT to valid compared to invalid spatial cues. RT increased when no spatial information was provided, interpreted as an increased difficulty to disengage from a direct gaze. RT was also increased when the robot was used instead of the human face and when the eyes of the stimuli were blacked out. Both effects were interpreted as resulting from an increased difficulty to disengage attention from the central stimulus because of its novelty. In all experiments, there was no interaction between cue validity and cue agent, implying that the exact nature of the human-like agent didn't have an effect on the automatic spatial orientation of attention. Altogether, our results imply that a humanoid face is as potent as a human face to trigger an automatic orientation of spatial attention. PMID:24027525

  16. Neural mechanisms of insect navigation.

    PubMed

    Webb, Barbara; Wystrach, Antoine

    2016-06-01

    We know more about the ethology of insect navigation than the neural substrates. Few studies have shown direct effects of brain manipulation on navigational behaviour; or measure brain responses that clearly relate to the animal's current location or spatial target, independently of specific sensory cues. This is partly due to the methodological problems of obtaining neural data in a naturally behaving animal. However, substantial indirect evidence, such as comparative anatomy and knowledge of the neural circuits that provide relevant sensory inputs provide converging arguments for the role of some specific brain areas: the mushroom bodies; and the central complex. Finally, modelling can help bridge the gap by relating the computational requirements of a given navigational task to the type of computation offered by different brain areas.

  17. Human Computer Interactions in Next-Generation of Aircraft Smart Navigation Management Systems: Task Analysis and Architecture under an Agent-Oriented Methodological Approach

    PubMed Central

    Canino-Rodríguez, José M.; García-Herrero, Jesús; Besada-Portas, Juan; Ravelo-García, Antonio G.; Travieso-González, Carlos; Alonso-Hernández, Jesús B.

    2015-01-01

    The limited efficiency of current air traffic systems will require a next-generation of Smart Air Traffic System (SATS) that relies on current technological advances. This challenge means a transition toward a new navigation and air-traffic procedures paradigm, where pilots and air traffic controllers perform and coordinate their activities according to new roles and technological supports. The design of new Human-Computer Interactions (HCI) for performing these activities is a key element of SATS. However efforts for developing such tools need to be inspired on a parallel characterization of hypothetical air traffic scenarios compatible with current ones. This paper is focused on airborne HCI into SATS where cockpit inputs came from aircraft navigation systems, surrounding traffic situation, controllers’ indications, etc. So the HCI is intended to enhance situation awareness and decision-making through pilot cockpit. This work approach considers SATS as a system distributed on a large-scale with uncertainty in a dynamic environment. Therefore, a multi-agent systems based approach is well suited for modeling such an environment. We demonstrate that current methodologies for designing multi-agent systems are a useful tool to characterize HCI. We specifically illustrate how the selected methodological approach provides enough guidelines to obtain a cockpit HCI design that complies with future SATS specifications. PMID:25746092

  18. Human computer interactions in next-generation of aircraft smart navigation management systems: task analysis and architecture under an agent-oriented methodological approach.

    PubMed

    Canino-Rodríguez, José M; García-Herrero, Jesús; Besada-Portas, Juan; Ravelo-García, Antonio G; Travieso-González, Carlos; Alonso-Hernández, Jesús B

    2015-03-04

    The limited efficiency of current air traffic systems will require a next-generation of Smart Air Traffic System (SATS) that relies on current technological advances. This challenge means a transition toward a new navigation and air-traffic procedures paradigm, where pilots and air traffic controllers perform and coordinate their activities according to new roles and technological supports. The design of new Human-Computer Interactions (HCI) for performing these activities is a key element of SATS. However efforts for developing such tools need to be inspired on a parallel characterization of hypothetical air traffic scenarios compatible with current ones. This paper is focused on airborne HCI into SATS where cockpit inputs came from aircraft navigation systems, surrounding traffic situation, controllers' indications, etc. So the HCI is intended to enhance situation awareness and decision-making through pilot cockpit. This work approach considers SATS as a system distributed on a large-scale with uncertainty in a dynamic environment. Therefore, a multi-agent systems based approach is well suited for modeling such an environment. We demonstrate that current methodologies for designing multi-agent systems are a useful tool to characterize HCI. We specifically illustrate how the selected methodological approach provides enough guidelines to obtain a cockpit HCI design that complies with future SATS specifications.

  19. Neural correlates of spatial and nonspatial attention determined using intracranial electroencephalographic signals in humans

    PubMed Central

    Park, Ga Young; Kim, Taekyung; Park, Jinsick; Lee, Eun Mi; Ryu, Han Uk; Kim, Sun I.; Kim, In Young; Husain, Masud

    2016-01-01

    Abstract Few studies have directly compared the neural correlates of spatial attention (i.e., attention to a particular location) and nonspatial attention (i.e., attention to a feature in the visual scene) using well‐controlled tasks. Here, we investigated the neural correlates of spatial and nonspatial attention in humans using intracranial electroencephalography. The topography and number of electrodes showing significant event‐related desynchronization (ERD) or event‐related synchronization (ERS) in different frequency bands were studied in 13 epileptic patients. Performance was not significantly different between the two conditions. In both conditions, ERD in the low‐frequency bands and ERS in the high‐frequency bands were present bilaterally in the parietal cortex (prominently on the right hemisphere) and frontal regions. In addition to these common changes, spatial attention involved right‐lateralized activity that was maximal in the right superior parietal lobule (SPL), whereas nonspatial attention involved wider brain networks including the bilateral parietal, frontal, and temporal regions, but still had maximal activity in the right parietal lobe. Within the parietal lobe, spatial attention involved ERD or ERS in the right SPL, whereas nonspatial attention involved ERD or ERS in the right inferior parietal lobule. These findings reveal that common as well as different brain networks are engaged in spatial and nonspatial attention. Hum Brain Mapp 37:3041–3054, 2016. © 2016 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc. PMID:27125904

  20. Spatial neural modulation transfer function of human foveal visual system for equiluminous chromatic gratings.

    PubMed

    Rovamo, J M; Kankaanpää, M I; Hallikainen, J

    2001-06-01

    To determine the spatial modulation transfer function (MTF) of the human foveal visual system for equiluminous chromatic gratings we measured contrast sensitivity as a function of retinal illuminance for spatial frequencies of 0.125-4 c/deg with equiluminous red-green and blue-yellow gratings. Contrast sensitivity for chromatic gratings first increased with luminance, obeying the Rose-DeVries law, but then the increase saturated and contrast sensitivity became independent of light level, obeying Weber's law. Critical retinal illuminance (I(c)) marking the transition point between the laws was found to be independent of spatial frequency at 165 phot. td. According to our detection model of human spatial vision the MTF of the retina and subsequent neural visual pathways (P(c)) is directly proportional to radicalI(c). Hence, P(c) is independent of spatial frequency, reflecting the lack of precortical lateral inhibition for equiluminous chromatic stimuli in spatiochromatically opponent retinal ganglion cells and dLGN neurons.

  1. Determination of optical parameters of human breast tissue from spatially resolved fluorescence: a diffusion theory model

    NASA Astrophysics Data System (ADS)

    Nair, Maya S.; Ghosh, Nirmalya; Raju, Narisetti Sundar; Pradhan, Asima

    2002-07-01

    We report the measurement of optical transport parameters of pathologically characterized malignant tissues, normal tissues, and different types of benign tumors of the human breast in the visible wavelength region. A spatially resolved steady-state diffuse fluorescence reflectance technique was used to estimate the values for the reduced-scattering coefficient (mu's) and the absorption coefficient (mua) of human breast tissues at three wavelengths (530, 550, and 590 nm). Different breast tissues could be well differentiated from one another, and different benign tumors could also be distinguished by their measured transport parameters. A diffusion theory model was developed to describe fluorescence light energy distribution, especially its spatial variation in a turbid and multiply scattering medium such as human tissue. The validity of the model was checked with a Monte Carlo simulation and also with different tissue phantoms prepared with polystyrene microspheres as scatterers, riboflavin as fluorophores, and methylene blue as absorbers.

  2. Contribution of geodiversity, climate and spatial variables for biodiversity across a gradient of human influence

    NASA Astrophysics Data System (ADS)

    Tukiainen, Helena; Alahuhta, Janne; Ala-Hulkko, Terhi; Field, Richard; Lampinen, Raino; Hjort, Jan

    2016-04-01

    Implementation of geodiversity may provide new perspectives for nature conservation. The relation between geodiversity and biodiversity has been established in recent studies but remains underexplored in environments with high human pressure. In this study, we explored the effect of geodiversity (i.e. geological, hydrological and geomorphological diversity), climate and spatial variables on biodiversity (vascular plant species richness) in environments with different human impact. The study area ranged trough the boreal vegetation zone in Finland and included altogether 1401 1-km2 grid cells from urban, rural and natural environments. The contribution of environmental variable groups for species diversity in different environments was statistically analyzed with variation partitioning method. According to the results, the contribution of geodiversity decreased and the contribution of climate and spatial variables increased as the land use became more human-induced. Hence, the connection between geodiversity and species richness was most pronounced in natural state environments.

  3. Mechanisms of homing in the fiddler crab Uca rapax. 1. Spatial and temporal characteristics of a system of small-scale navigation.

    PubMed

    Layne, John E; Barnes, W Jon P; Duncan, Lindsey M J

    2003-12-01

    Fiddler crabs Uca rapax are central-place foragers, making feeding excursions of up to 2 m from their burrows. We describe the natural feeding excursions of path-integrating fiddler crabs and analyze their paths for signs of significant systematic or random navigation errors. No signs of any systematic errors are evident. Random errors are small, probably due to a combination of the short length and low sinuosity of the foraging paths, as well as the fiddler crabs' unique method of locomotion that allows them to remain oriented to their burrows throughout the foraging path and to minimize large body turns. We further examined the extent to which their body orientation during foraging (transverse body axis pointing more or less towards home) accurately represented their stored home vector. By examining sequences of fast escape, we have shown that crabs can correct for deviations of their transverse body axis from home during their escape path. Thus their stored home vector is independent of their moment-to-moment body orientation. Crabs were subjected to passive translational displacements and barrier obstructions. Responses to translational displacements were identical to those observed by previous authors, namely that crabs returned in the correct egocentric direction and distance as though no displacement had occurred. Covering the burrow entrance resulted in crabs returning to the correct position of the burrow, and then beginning to search. When a barrier was placed between foraging crabs and their burrow, crabs oriented their bodies toward the burrow as accurately as with no barrier.

  4. Wikipedia Entries as a Source of CAR Navigation Landmarks

    NASA Astrophysics Data System (ADS)

    Binski, N.; Zhang, L.; Dalyot, S.

    2016-06-01

    Car navigation system devices provide today with an easy and simple solution to the basic concept of reaching a destination. Although these systems usually achieve this goal, they still deliver a limited and poor sequence of instructions that do not consider the human nature of using landmarks during wayfinding. This research paper addresses the concept of enriching navigation route instructions by adding supplementary route information in the form of landmarks. We aim at using a contributed source of landmarks information, which is easy to access, available, show high update rate, and have a large scale of information. For this, Wikipedia was chosen, since it represents the world's largest free encyclopaedia that includes information about many spatial entities. A survey and classification of available landmarks is implemented, coupled with ranking algorithms based on the entries' categories and attributes. These are aimed at retrieving the most relevant landmark information required that are valuable for the enrichment of a specific navigation route. The paper will present this methodology, together with examples and results, showing the feasibility of using this concept and its potential of enriching navigation processes.

  5. Climate and Human Pressure Constraints Co-Explain Regional Plant Invasion at Different Spatial Scales

    PubMed Central

    García-Baquero, Gonzalo; Caño, Lidia; Biurrun, Idoia; García-Mijangos, Itziar; Loidi, Javier; Herrera, Mercedes

    2016-01-01

    Alien species invasion represents a global threat to biodiversity and ecosystems. Explaining invasion patterns in terms of environmental constraints will help us to assess invasion risks and plan control strategies. We aim to identify plant invasion patterns in the Basque Country (Spain), and to determine the effects of climate and human pressure on that pattern. We modeled the regional distribution of 89 invasive plant species using two approaches. First, distance-based Moran’s eigenvector maps were used to partition variation in the invasive species richness, S, into spatial components at broad and fine scales; redundancy analysis was then used to explain those components on the basis of climate and human pressure descriptors. Second, we used generalized additive mixed modeling to fit species-specific responses to the same descriptors. Climate and human pressure descriptors have different effects on S at different spatial scales. Broad-scale spatially structured temperature and precipitation, and fine-scale spatially structured human population density and percentage of natural and semi-natural areas, explained altogether 38.7% of the total variance. The distribution of 84% of the individually tested species was related to either temperature, precipitation or both, and 68% was related to either population density or natural and semi-natural areas, displaying similar responses. The spatial pattern of the invasive species richness is strongly environmentally forced, mainly by climate factors. Since individual species responses were proved to be both similarly constrained in shape and explained variance by the same environmental factors, we conclude that the pattern of invasive species richness results from individual species’ environmental preferences. PMID:27741276

  6. Climate and Human Pressure Constraints Co-Explain Regional Plant Invasion at Different Spatial Scales.

    PubMed

    Campos, Juan Antonio; García-Baquero, Gonzalo; Caño, Lidia; Biurrun, Idoia; García-Mijangos, Itziar; Loidi, Javier; Herrera, Mercedes

    2016-01-01

    Alien species invasion represents a global threat to biodiversity and ecosystems. Explaining invasion patterns in terms of environmental constraints will help us to assess invasion risks and plan control strategies. We aim to identify plant invasion patterns in the Basque Country (Spain), and to determine the effects of climate and human pressure on that pattern. We modeled the regional distribution of 89 invasive plant species using two approaches. First, distance-based Moran's eigenvector maps were used to partition variation in the invasive species richness, S, into spatial components at broad and fine scales; redundancy analysis was then used to explain those components on the basis of climate and human pressure descriptors. Second, we used generalized additive mixed modeling to fit species-specific responses to the same descriptors. Climate and human pressure descriptors have different effects on S at different spatial scales. Broad-scale spatially structured temperature and precipitation, and fine-scale spatially structured human population density and percentage of natural and semi-natural areas, explained altogether 38.7% of the total variance. The distribution of 84% of the individually tested species was related to either temperature, precipitation or both, and 68% was related to either population density or natural and semi-natural areas, displaying similar responses. The spatial pattern of the invasive species richness is strongly environmentally forced, mainly by climate factors. Since individual species responses were proved to be both similarly constrained in shape and explained variance by the same environmental factors, we conclude that the pattern of invasive species richness results from individual species' environmental preferences.

  7. Spatial variability of muscle activity during human walking: the effects of different EMG normalization approaches.

    PubMed

    Cronin, N J; Kumpulainen, S; Joutjärvi, T; Finni, T; Piitulainen, H

    2015-08-06

    Human leg muscles are often activated inhomogeneously, e.g. in standing. This may also occur in complex tasks like walking. Thus, bipolar surface electromyography (sEMG) may not accurately represent whole muscle activity. This study used 64-electrode high-density sEMG (HD-sEMG) to examine spatial variability of lateral gastrocnemius (LG) muscle activity during the stance phase of walking, maximal voluntary contractions (MVCs) and maximal M-waves, and determined the effects of different normalization approaches on spatial and inter-participant variability. Plantar flexion MVC, maximal electrically elicited M-waves and walking at self-selected speed were recorded in eight healthy males aged 24-34. sEMG signals were assessed in four ways: unnormalized, and normalized to MVC, M-wave or peak sEMG during the stance phase of walking. During walking, LG activity varied spatially, and was largest in the distal and lateral regions. Spatial variability fluctuated throughout the stance phase. Normalizing walking EMG signals to the peak value during stance reduced spatial variability within LG on average by 70%, and inter-participant variability by 67%. Normalizing to MVC reduced spatial variability by 17% but increased inter-participant variability by 230%. Normalizing to M-wave produced the greatest spatial variability