Spatial Reorientation Research Articles

Chicks, like children, spontaneously reorient by three-dimensional environmental geometry, not by image matching

Spatial reorientation by layout geometry occurs in numerous species, but its underlying mechanisms are debated. While some argue that navigating animals' sense of place is based on geometric computations over three-dimensional representations, others claim it depends on panoramic image-matching processes. Because children reorient by subtle three-dimensional perturbations of the terrain and not by salient two-dimensional brightness contours on surfaces or freestanding columns, children's sense of place cannot be explained by image matching. To test image-matching theories in a different species, the present experiment investigates the reorientation performance of domestic chicks (Gallus gallus) in environments similar to those used with children. Chicks, like children, spontaneously reoriented by geometric relationships of subtle three-dimensional terrains, and not by salient two-dimensional brightness contours on surfaces or columns. These findings add to the evidence for homologous navigation systems in humans and other vertebrates, and they cast doubt on image-matching theories of reorientation in these species.

Malleability in the development of spatial reorientation

After becoming disoriented, organisms must re-establish their position in space. The core knowledge position argues that reorientation relies only on extended 3D surfaces, and that this sensitivity operates automatically and is innately present. In contrast, the adaptive combination perspective argues that reorientation is experience-expectant and malleable, and depends on both extended 3D surfaces and 2D feature cues. We test these divergent views by comparing young (Experiment 1) and mature (Experiment 2) C57BL/6 mice (Mus musculus) that have been housed in circular or rectangular environments. Malleability of feature cues was found for young mice. Malleability of incidental geometry coding was found for both age groups. The relative dependence on geometric and feature cues changed with age. Young mice weighted the feature cue more heavily than adult mice. In summary, as predicted by the adaptive combination approach, rearing environments influenced the relative use of feature and geometric cues in a reorientation task.

Spatial reorientation by geometry with freestanding objects and extended surfaces: a unifying view

The macroscopic, three-dimensional surface layout geometry of an enclosure apparently provides a different contribution for spatial reorientation than the geometric cues associated with freestanding objects arranged in arrays with similar geometric shape. Here, we showed that a unitary spatial representation can account for the capability of animals to reorient both by extended surfaces and discrete objects in a small-scale spatial task. We trained domestic chicks to locate a food-reward from an opening on isolated cylinders arranged either in a geometrically uninformative (square-shaped) or informative (rectangular-shaped) arrays. The arrays were located centrally within a rectangular-shaped enclosure. Chicks trained to access the reward from a fixed position of openings proved able to reorient according to the geometric cues specified by the shape of the enclosure in all conditions. Chicks trained in a fixed position of opening with geometric cues provided both by the arena and the array proved able to reorient according to each shape separately. However, chicks trained to access the reward from a variable position of openings failed to reorient. The results suggest that the physical constrains associated with the presence of obstacles in a scene, rather than their apparent visual extension, are crucial for spatial reorientation.

Formula omitted] radicals in ε-cages of cancrinite and zeolite L: Spectroscopic and magnetic resonance studies

Spectroscopic methods such as UV–Vis, Raman, ESR and electron spin echo were applied for characterization of polysulfide chromophore thermally formed in cancrinite and zeolite L containing ε-cages in their structures. The UV–Vis and Raman spectra indicated predominant contribution of oligosulfides S n (with n = 2–4) in samples prepared at 650 °C from mixtures of medium alkalinity. Estimated number of S 3 - (blue chromophore) was two orders of magnitude lower (∼3 × 10 16 radicals/g) than in pigments with sodalite or zeolite A structures where it is located in β-cages. The number of S 2 - (yellow chromophore) was even smaller. The continuous ESR and pulse ESR measurements at room temperature and at 10 K indicated that most (>90%) of S 3 - radicals are localized inside ε-cages and remaining ones exhibit free reorientations. The localization in the ε-cages well explains a shift of ESR g-factors compared to that observed for radicals localized in β-cages as well as different dynamical behavior of radical molecules i.e. reorientations around c-axis instead of spatial reorientations existing in β-cages at room temperature.

Wayfinding and Spatial Reorientation by Nova Scotia Deer Hunters

How do backcountry travelers respond to losing their way? To address this question, deer hunters were surveyed in regard to their attitudes toward various methods of recovering one’s spatial orientation. Ratings of the likelihood of adopting each of nine reorientation strategies—or advice on what to do on becoming “lost” in the woods—revealed that “climbing a tree or hill for a better view” was rated highest among alternatives. One strategy, “try to travel a straight line out of the woods,” was positively correlated with respondents’ self-reports of having been lost while hunting. Principal components analysis of reorientation strategies yielded four components, labeled “skill based” (e.g., using environmental cues to travel a straight line), “downhill” (e.g., following a stream), “perception based” (improving visual access), and “wandering” (e.g., traveling the path of least resistance). The importance of spatial reorientation to general wayfinding skill was discussed.

Variations of the equilibrium make-up and spatial orientation of a molecular layer of polymethine dyes

Molecular layers of polymethine dyes on glass substrates have been investigated. As the surface concentration of molecules increases, the number of cis isomers of various structures decreases, and the relative concentration of all-trans isomers increases. The increased electron-donorability of the end groups and the lengthening of the conjugation chain increases the number of cis isomers of various structures. The equilibrium stereoisomer composition of the molecular layer is determined by the degree of asymmetry of the intramolecular electron-density distribution induced by its interaction with the substrate. A model is proposed for the reconstruction of the structure of the layer under the action of heating and photoexcitation. Reversible changes in the make-up of the layer are caused by stereoisomerization when a segment of a molecule rotates around the second bond of the conjugation chain; irreversible changes are caused by transformations in the asymmetry of the electron-density distribution in the molecule due to irreversible spatial reorientation of the components of the layer.

Actin is Involved in Pollen Tube Tropism Through Redefining the Spatial Targeting of Secretory Vesicles

In order to accurately target the embryo sac and deliver the sperm cells, the pollen tube has to find an efficient path through the pistil and respond to precise directional cues produced by the female tissues. Although many chemical and proteic signals have been identified to guide pollen tube growth, the mechanism by which the tube changes direction in response to these signals is poorly understood. We designed an experimental setup using a microscope-mounted galvanotropic chamber that allowed us to induce the redirection of in vitro pollen tube growth through a precisely timed and calibrated external signal. Actin destabilization, reduced calcium concentration in the growth medium and inhibition of calcium channel activity decreased the responsiveness of the pollen tube to a tropic trigger. An increased calcium concentration in the medium enhanced this response and was able to rescue the effect of actin depolymerization. Time-lapse imaging revealed that the motion pattern of vesicles and the dynamics of the subapical actin array undergo spatial reorientation prior to the onset of a tropic response. Together these results suggest that the precise targeting of the delivery of new wall material represents a key component in the growth machinery that determines directional elongation in pollen tubes.

Stable Panoramic Views Facilitate Snap-Shot Like Memories for Spatial Reorientation in Homing Pigeons

Following spatial disorientation, animals can reorient themselves by relying on geometric cues (metric and sense) specified both by the macroscopic surface layout of an enclosed space and prominent visual landmarks in arrays. Whether spatial reorientation in arrays of landmarks is based on explicit representation of the geometric cues is a matter of debate. Here we trained homing pigeons (Columba livia) to locate a food-reward in a rectangular array of four identical or differently coloured pipes provided with four openings, only one of which allowed the birds to have access to the reward. Pigeons were trained either with a stable or a variable position of the opening on pipes, so that they could view the array either from the same or a variable perspective. Explicit mapping of configural geometry would predict successful reorientation irrespective of access condition. In contrast, we found that a stable view of the array facilitated spatial learning in homing pigeons, likely through the formation of snapshot-like memories.

SOS1 mutations in Noonan syndrome: molecular spectrum, structural insights on pathogenic effects, and genotype-phenotype correlations

Noonan syndrome (NS) is among the most common nonchromosomal disorders affecting development and growth. NS is caused by aberrant RAS-MAPK signaling and is genetically heterogeneous, which explains, in part, the marked clinical variability documented for this Mendelian trait. Recently, we and others identified SOS1 as a major gene underlying NS. Here, we explored further the spectrum of SOS1 mutations and their associated phenotypic features. Mutation scanning of the entire SOS1 coding sequence allowed the identification of 33 different variants deemed to be of pathological significance, including 16 novel missense changes and in-frame indels. Various mutation clusters destabilizing or altering orientation of regions of the protein predicted to contribute structurally to the maintenance of autoinhibition were identified. Two previously unappreciated clusters predicted to enhance SOS1's recruitment to the plasma membrane, thus promoting a spatial reorientation of domains contributing to inhibition, were also recognized. Genotype–phenotype analysis confirmed our previous observations, establishing a high frequency of ectodermal anomalies and a low prevalence of cognitive impairment and reduced growth. Finally, mutation analysis performed on cohorts of individuals with nonsyndromic pulmonic stenosis, atrial septal defects, and ventricular septal defects excluded a major contribution of germline SOS1 lesions to the isolated occurrence of these cardiac anomalies. Hum Mutat 32:760–772, 2011. © 2011 Wiley-Liss, Inc.

Optimal control of reorientation of a spacecraft using free trajectory method

The problem of optimal control over spatial reorientation of a spacecraft is considered. The functional having a sense of propellant consumption is minimized. The analytical solution to the formulated problem is presented. It is shown that the optimal solution can be found in the class of two-impulse control at which the spacecraft’s turn is performed along a free motion trajectory. In order to improve the accuracy of spacecraft guidance into a specified angular position, methods of control are suggested that realize the method of free trajectories. The synthesized controls are invariant with respect to both external perturbations and parametric errors. The results of mathematical modeling are presented that demonstrate high efficiency of developed control algorithms. Propellant consumption for realizing a programmed turn is numerically estimated taking into account considerable gravitational and aerodynamic moments acting upon the spacecraft.

Controlling the Spatial Orientation of Molecular Actuators: Polarized Photoisomerization of 2-Nitro-9-(2,2,2-triphenylethylidene)fluorene in a Thin Polymer Matrix

The molecule 2-nitro-9-(2,2,2-triphenylethylidene)fluorene (NTEF) was studied as a potential light-driven molecular motor. Absorption at 355 nm causes a reversible spatial reorientation of the angular distribution of the dibenzofulvene rotor moiety of NTEF when immobilized in a poly(methyl methacrylate) (PMMA) matrix adsorbed on a fused silica surface in air at room temperature. The photoreorientation dynamics was probed by polarized normal incidence cavity ringdown spectroscopy (NICRDS) when the matrix was irradiated by linearly polarized "drive" light. Polarized drive irradiation at 355 nm creates a "hole" in the angular distribution of the molecular transition dipoles. Changing the polarization of the drive beam refills the hole, creating a new hole. A stochastic model was fitted to the experimental hole burning measurements to obtain a photoreorientation quantum yield (Φ(reorient) = 0.014). The photoreorientation process appears to be driven by photoisomerization of the exocyclic dibenzofulvene double bond of NTEF.

Controlling space vehicle reorientation with minimal energy integral

We consider the optimal control problem for spatial reorientation of a space vehicle (SV) from an arbitrary initial to a given final angular position. The reorientation time is known in advance, so we are minimizing the rotation energy integral. We present an analytic solution of the proposed problem. With the method of quaternions, we have obtained formal equations and computational expressions for constructing the optimal reorientation program. For a dynamically symmetric SV, we give a complete solution of the SV reorientation problem in closed form. We give an example and mathematical modeling results for SV motion dynamics under optimal control. These results demonstrate that the developed method of controlling SV spatial orientation is feasible in practice.

Spinning in the scanner: Neural correlates of virtual reorientation.

Recent studies have used spatial reorientation task paradigms to identify underlying cognitive mechanisms of navigation in children, adults, and a range of animal species. Despite broad interest in this task across disciplines, little is known about the brain bases of reorientation. We used functional magnetic resonance imaging to examine neural activity in adults during a virtual reality version of the reorientation task. Three environments that varied in the cues provided were studied: a rectangular room with 4 identical gray walls (Geometry), a square room with 3 gray walls and 1 red wall (Feature), and a rectangular room with 3 gray walls and 1 red wall (Feature + Geometry). Multiple areas within the medial temporal lobe (MTL) showed increased activation when a feature was present compared with when reorientation was based only on geometric cues. In contrast, reliance on geometric cues significantly activated a number of non-MTL structures, including the prefrontal cortex and inferior temporal gyrus. These results provide neural evidence for processing differences between the 2 types of cue as well as insight into developmental and comparative aspects of reorientation.

Sex differences in the processing of flankers

The study of sex differences in cognition has often focused on differences in spatial processing. Recently, sex differences in selective attention have been observed by Bayliss, di Pellegrino, and Tipper (2005), showing that women are more influenced than men by irrelevant spatial cues. The current study elaborates on this finding and tests whether sex differences in the processing of irrelevant information also occur in a simpler task, in which there is no need to redirect visual attention and no need to remember multiple spatial stimulus-response associations. Here, attention is studied using a novel combination of a go/no-go task and a flanker task. A total of 80 neurotypical participants were studied, and it was found that responses in women were more strongly affected by flanker information than were responses in men. This suggests that these sex differences were not due to difficulties with spatial reorientation, or remembering spatial stimulus-response relationships. The findings are discussed in the context of the hunter-gatherer theory of sex differences.

Use of geometry for spatial reorientation in children applies only to symmetric spaces

Proponents of the geometric module hypothesis argue that following disorientation, many species reorient by use of macro-environment geometry. It is suggested that attention to the surface layout geometry of natural terrain features may have been selected for over evolutionary time due to the enduring and unambiguous location information it provides. Paradoxically, however, tests of the hypothesis have been exclusively conducted in symmetric (hence 'unnatural' and geometrically ambiguous) environments. The present series of studies examines reorientation by 18-month-3-year-old children in a rectangular versus irregular quadrilateral enclosure (Study 1), a rectangular versus irregular quadrilateral array (Study 2) and an isosceles versus irregular triangular array (Study 3). Children were successful in symmetric but not asymmetric environments, casting doubt on the functional argument for an empirical basis of the geometric module hypothesis.

Differential activation of frontoparietal attention networks by social and symbolic spatial cues

Perception of both gaze-direction and symbolic directional cues (e.g. arrows) orient an observer’s attention toward the indicated location. It is unclear, however, whether these similar behavioral effects are examples of the same attentional phenomenon and, therefore, subserved by the same neural substrate. It has been proposed that gaze, given its evolutionary significance, constitutes a ‘special’ category of spatial cue. As such, it is predicted that the neural systems supporting spatial reorienting will be different for gaze than for non-biological symbols. We tested this prediction using functional magnetic resonance imaging to measure the brain’s response during target localization in which laterally presented targets were preceded by uninformative gaze or arrow cues. Reaction times were faster during valid than invalid trials for both arrow and gaze cues. However, differential patterns of activity were evoked in the brain. Trials including invalid rather than valid arrow cues resulted in a stronger hemodynamic response in the ventral attention network. No such difference was seen during trials including valid and invalid gaze cues. This differential engagement of the ventral reorienting network is consistent with the notion that the facilitation of target detection by gaze cues and arrow cues is subserved by different neural substrates.

Extending the 'dorsal stream vulnerability hypothesis': Spatial reorientation and motion and form coherence in children and adults with Williams syndrome

Extending the 'dorsal stream vulnerability hypothesis': Spatial reorientation and motion and form coherence in children and adults with Williams syndrome

Language and spatial reorientation: Evidence from severe aphasia.

Investigating spatial cognition in individuals with acquired language impairments can inform our understanding of how components of language are involved in spatial representation. Using the reorientation paradigm of Hermer-Vazquez, Spelke, and Katsnelson (1999), we examined spatial cue integration (landmark-geometry conjunctions) in individuals with severe agrammatic or global aphasia and in a group of healthy older adults. Participants with aphasia performed similarly to healthy controls in the reorientation task, demonstrating the ability to integrate landmark and geometric cues, even during a concurrent verbal task designed to block access to any residual lexical resources. These results extend previous findings with healthy adults by suggesting that neither syntax nor lexicon is essential for spatial cue representation in a mature cognitive system, and provide further evidence that language deficits in aphasia can be independent from other domains of reasoning.

Reorienting strategies in a rectangular array of landmarks by domestic chicks (gallus gallus).

Spatial reorientation in a rectangular array of four landmarks located in the center of a circular enclosure was investigated in domestic chicks (Gallus gallus). One of the landmark possessed unique visual features, indicating the location of a food reward. After training, chicks were tested (a) with the same array as during the training; (b) with four identical landmarks of the type previously nonrewarded, of the type previously rewarded, or of a new type; (c) after having transformed one of the landmarks located at the geometric incorrect location into the type of landmark previously rewarded; or (d) with a fifth landmark of the rewarded type at a new location. Chicks encoded information provided by local featural cues but not the geometric information provided by the shape of the array. Moreover, when trained in a rectangular array of identical landmarks chicks failed to reorient. In a second series of experiments, the array was located in correspondence to the corners of a rectangular enclosure. This time chicks successfully learned to locate the reward using geometric information. However, when the rectangular array was located in the center of a larger rectangular enclosure, chicks failed to reorient, indicating that the geometric information given by the macroscopic layout of arena surfaces was not used to specify different locations. These results suggest that chicks reorient on the basis of a local representation of single landmarks and that encoding of the global aspects of geometry only occurs with respect to the large, extended surfaces of an enclosure.

Арктические горизонты стратегии России: современная динамика

As a result of struggle between two concept-lines in prescriptive documents (concepts, strategies, doctrines) of the Russian Federation, certain compromise is reached between a popular ultra-liberal approach and national patriotic appeals for state development spatial reorientation. Having analyzed geopolitical aspirations of five Arctic states – Denmark, Canada, the USA, Norway, Russia (as well as NATO and the EU activities), and the legal regime of the Arctic, the author comes to a conclusion that, anyhow, no horrifying fight/race battle for possession of its territories or resources is taking place in practice. There is every indication to believe that all Arctic states will adhere to the existing and framing rules of international law (especially the UN Convention on the Law of the Sea, 1982).