scholarly journals A novel time-stamp mechanism transforms egocentric encounters into an allocentric spatial representation

2018 ◽  
Author(s):  
Avner Wallach ◽  
Erik Harvey-Girard ◽  
James Jaeyoon Jun ◽  
André Longtin ◽  
Leonard Maler

AbstractLearning the spatial organization of the environment is essential for most animals’ survival. This often requires the animal to derive allocentric information about the environment from egocentric sensory and motor experience. The neural circuits and mechanisms underlying this transformation are currently unknown. We addressed this problem in electric fish, which can precisely navigate in complete darkness and whose requisite brain circuitry is relatively simple. We conducted the first neural recordings in the preglomerular complex, the thalamic region exclusively connecting the optic tectum with the spatial learning circuits in the dorsolateral pallium. While tectal egocentric information was eliminated in preglomerular neurons, the time-intervals between object encounters were precisely encoded. We show that this highly-reliable temporal information, combined with a speed signal, can permit accurate path-integration that then enables computing allocentric spatial relations. Our results suggest that similar mechanisms are involved in spatial learning via sequential encounters in all vertebrates.

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Avner Wallach ◽  
Erik Harvey-Girard ◽  
James Jaeyoon Jun ◽  
André Longtin ◽  
Len Maler

Learning the spatial organization of the environment is essential for most animals’ survival. This requires the animal to derive allocentric spatial information from egocentric sensory and motor experience. The neural mechanisms underlying this transformation are mostly unknown. We addressed this problem in electric fish, which can precisely navigate in complete darkness and whose brain circuitry is relatively simple. We conducted the first neural recordings in the preglomerular complex, the thalamic region exclusively connecting the optic tectum with the spatial learning circuits in the dorsolateral pallium. While tectal topographic information was mostly eliminated in preglomerular neurons, the time-intervals between object encounters were precisely encoded. We show that this reliable temporal information, combined with a speed signal, can permit accurate estimation of the distance between encounters, a necessary component of path-integration that enables computing allocentric spatial relations. Our results suggest that similar mechanisms are involved in sequential spatial learning in all vertebrates.


Author(s):  
Alessandro Araldi ◽  
Giovanni Fusco

The Nine Forms of the French Riviera: Classifying Urban Fabrics from the Pedestrian Perspective. Giovanni Fusco, Alessandro Araldi ¹Université Côte-Azur, CNRS, ESPACE - Bd. Eduard Herriot 98. 06200 Nice E-mail: [email protected], [email protected] Keywords: French Riviera, Urban Fabrics, Urban Form Recognition, Geoprocessing Conference topics and scale: Tools of analysis in urban morphology     Recent metropolitan growth produces new kinds of urban fabric, revealing different logics in the organization of urban space, but coexisting with more traditional urban fabrics in central cities and older suburbs. Having an overall view of the spatial patterns of urban fabrics in a vast metropolitan area is paramount for understanding the emerging spatial organization of the contemporary metropolis. The French Riviera is a polycentric metropolitan area of more than 1200 km2 structured around the old coastal cities of Nice, Cannes, Antibes and Monaco. XIX century and early XX century urban growth is now complemented by modern developments and more recent suburban areas. A large-scale analysis of urban fabrics can only be carried out through a new geoprocessing protocol, combining indicators of spatial relations within urban fabrics, geo-statistical analysis and Bayesian data-mining. Applied to the French Riviera, nine families of urban fabrics are identified and correlated to the historical periods of their production. Central cities are thus characterized by the combination of different families of pre-modern, dense, continuous built-up fabrics, as well as by modern discontinuous forms. More interestingly, fringe-belts in Nice and Cannes, as well as the techno-park of Sophia-Antipolis, combine a spinal cord of connective artificial fabrics having sparse specialized buildings, with the already mentioned discontinuous fabrics of modern urbanism. Further forms are identified in the suburban and “rurban” spaces around central cities. The proposed geoprocessing procedure is not intended to supersede traditional expert-base analysis of urban fabric. Rather, it should be considered as a complementary tool for large urban space analysis and as an input for studying urban form relation to socioeconomic phenomena. References   Conzen, M.R.G (1960) Alnwick, Northumberland : A Study in Town-Planning Analysis. (London, George Philip). Conzen, M.P. (2009) “How cities internalize their former urban fringe. A cross-cultural comparison”. Urban Morphology, 13, 29-54. Graff, P. (2014) Une ville d’exception. Nice, dans l'effervescence du 20° siècle. (Serre, Nice). Yamada I., Thill J.C. (2010) “Local indicators of network-constrained clusters in spatial patterns represented by a link attribute.” Annals of the Association of American Geographers, 100(2), 269-285. Levy, A. (1999) “Urban morphology and the problem of modern urban fabric : some questions for research”, Urban Morphology, 3(2), 79-85. Okabe, A. Sugihara, K. (2012) Spatial Analysis along Networks: Statistical and Computational Methods. (John Wiley and sons, UK).


Medicina ◽  
2020 ◽  
Vol 56 (9) ◽  
pp. 452
Author(s):  
Salvatore Bertino ◽  
Gianpaolo Antonio Basile ◽  
Giuseppe Anastasi ◽  
Alessia Bramanti ◽  
Bartolo Fonti ◽  
...  

Background and objectives: The internal (GPi) and external segments (GPe) of the globus pallidus represent key nodes in the basal ganglia system. Connections to and from pallidal segments are topographically organized, delineating limbic, associative and sensorimotor territories. The topography of pallidal afferent and efferent connections with brainstem structures has been poorly investigated. In this study we sought to characterize in-vivo connections between the globus pallidus and the pedunculopontine nucleus (PPN) via diffusion tractography. Materials and Methods: We employed structural and diffusion data of 100 subjects from the Human Connectome Project repository in order to reconstruct the connections between the PPN and the globus pallidus, employing higher order tractography techniques. We assessed streamline count of the reconstructed bundles and investigated spatial relations between pallidal voxels connected to the PPN and pallidal limbic, associative and sensorimotor functional territories. Results: We successfully reconstructed pallidotegmental tracts for the GPi and GPe in all subjects. The number of streamlines connecting the PPN with the GPi was greater than the number of those joining it with the GPe. PPN maps within pallidal segments exhibited a distinctive spatial organization, being localized in the ventromedial portion of the GPi and in the ventral-anterior portion in the GPe. Regarding their spatial relations with tractography-derived maps of pallidal functional territories, the highest value of percentage overlap was noticed between PPN maps and the associative territory. Conclusions: We successfully reconstructed the anatomical course of the pallidotegmental pathways and comprehensively characterized their topographical arrangement within both pallidal segments. PPM maps were localized in the ventromedial aspect of the GPi, while they occupied the anterior pole and the most ventral portion of the GPe. A better understanding of the spatial and topographical arrangement of the pallidotegmental pathways may have pathophysiological and therapeutic implications in movement disorders.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Alexander A. Nevue ◽  
Peter V. Lovell ◽  
Morgan Wirthlin ◽  
Claudio V. Mello

Abstract How the evolution of complex behavioral traits is associated with the emergence of novel brain pathways is largely unknown. Songbirds, like humans, learn vocalizations via tutor imitation and possess a specialized brain circuitry to support this behavior. In a comprehensive in situ hybridization effort, we show that the zebra finch vocal robust nucleus of the arcopallium (RA) shares numerous markers (e.g. SNCA, PVALB) with the adjacent dorsal intermediate arcopallium (AId), an avian analog of mammalian deep cortical layers with involvement in motor function. We also identify markers truly unique to RA and thus likely linked to modulation of vocal motor function (e.g. KCNC1, GABRE), including a subset of the known shared markers between RA and human laryngeal motor cortex (e.g. SLIT1, RTN4R, LINGO1, PLXNC1). The data provide novel insights into molecular features unique to vocal learning circuits, and lend support for the motor theory for vocal learning origin.


2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Mikhail Lebedev

AbstractBrain-machine interfaces (BMIs) hold promise to treat neurological disabilities by linking intact brain circuitry to assistive devices, such as limb prostheses, wheelchairs, artificial sensors, and computers. BMIs have experienced very rapid development in recent years, facilitated by advances in neural recordings, computer technologies and robots. BMIs are commonly classified into three types: sensory, motor and bidirectional, which subserve motor, sensory and sensorimotor functions, respectively. Additionally, cognitive BMIs have emerged in the domain of higher brain functions. BMIs are also classified as noninvasive or invasive according to the degree of their interference with the biological tissue. Although noninvasive BMIs are safe and easy to implement, their information bandwidth is limited. Invasive BMIs hold promise to improve the bandwidth by utilizing multichannel recordings from ensembles of brain neurons. BMIs have a broad range of clinical goals, as well as the goal to enhance normal brain functions.


2013 ◽  
Vol 30 (1) ◽  
pp. 106-136 ◽  
Author(s):  
Juan Chen ◽  
Anthony G. Cohn ◽  
Dayou Liu ◽  
Shengsheng Wang ◽  
Jihong Ouyang ◽  
...  

AbstractRepresentation and reasoning with qualitative spatial relations is an important problem in artificial intelligence and has wide applications in the fields of geographic information system, computer vision, autonomous robot navigation, natural language understanding, spatial databases and so on. The reasons for this interest in using qualitative spatial relations include cognitive comprehensibility, efficiency and computational facility. This paper summarizes progress in qualitative spatial representation by describing key calculi representing different types of spatial relationships. The paper concludes with a discussion of current research and glimpse of future work.


2019 ◽  
Vol 13 (1-2) ◽  
pp. 39-52 ◽  
Author(s):  
Tim Cole ◽  
Torsten Hahmann

This article responds to the widespread and oft-noted challenges digital humanists face in working with data that is uncertain and characterised by complex narratives. Using an example drawn from the vast archives of post-war interviews with Holocaust survivors, it draws on approaches developed in Qualitative Spatial Representation (QSR) to explore how two key spatial aspects of survivor's narratives – their uncertain wartime trajectories and the slippage in scales as these are retold – can be represented. Spatial information in narratives tends to not provide the exact coordinates necessary to store the information in geospatial databases. Instead, narratives rely much more on often less precise qualitative spatial relations such as ‘near’, ‘next to’, ‘at the corner of’ without precise geometric interpretations. Given that relational databases are ill-equipped to store this kind of relational spatial knowledge from natural language sources, the article argues for a need for digital humanists to return to first principles and reconsider database design. Descriptive triple-based graph representations, which have been devised to accommodate this kind of highly irregular, semi-structured relational knowledge, have the potential to work with, rather than against, the grain of the narrative sources that underlie the work of much of the digital humanities.


2012 ◽  
Vol 65 (6) ◽  
pp. 1044-1051 ◽  
Author(s):  
Kevin J. Holmes

While research on the spatial representation of number has provided substantial evidence for a horizontally oriented mental number line, recent studies suggest vertical organization as well. Directly comparing the relative strength of horizontal and vertical organization, however, we found no evidence of spontaneous vertical orientation (upward or downward), and horizontal trumped vertical when pitted against each other (Experiment 1). Only when numbers were conceptualized as magnitudes (as opposed to nonmagnitude ordinal sequences) did reliable vertical organization emerge, with upward orientation preferred (Experiment 2). Altogether, these findings suggest that horizontal representations predominate, and that vertical representations, when elicited, may be relatively inflexible. Implications for spatial organization beyond number, and its ontogenetic basis, are discussed.


2013 ◽  
Vol 36 (5) ◽  
pp. 559-560 ◽  
Author(s):  
Achille Pasqualotto ◽  
Michael J. Proulx

AbstractJeffery et al. suggest that three-dimensional environments are not represented according to their volumetric properties, but in a quasi-planar fashion. Here we take into consideration the role of visual experience and the use of technology for spatial learning to better understand the nature of the preference of horizontal over vertical spatial representation.


1997 ◽  
Vol 85 (3) ◽  
pp. 947-959 ◽  
Author(s):  
Anneliese A. Pontius

A rank-order correlation was performed for nine cultural groups ranging from preliterate hunter-gatherers to literate medium-city dwellers. Two spatial tests of intrapattern spatial relations were used, the Draw-A-Person-With-Face-In-Front test and the Kohs Block Design, a test of constructive praxia. In contrast to traditional “Western” evaluations, credit was given for the preservation of the essential intrapattern shapes even when exact spatial relations among these shapes was incorrect. Such “errors” were labelled “neolithic face” patterns and “nonrandom errors,” respectively. Analysis suggested that the neglected intrapattern (in contrast to interobject) spatial relational skills emerge with literacy but is not yet actualized in preliterates whose survival requires quick fight or flight response upon prompt, albeit gross, assessment of salient shapes of prey or predators (human or animals). The positive Spearman rank-order correlarion of absent or low literacy skills with the percent of “neolithic face” drawings was .95 and with the “nonrandom” block designs .67. Suggestions were developed for assessing certain unusual “ecological” present situations or certain brain dysfunctions.


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