Egocentric Strategy Research Articles

Impairments in reversal learning following short access to cocaine self-administration

BackgroundCocaine use disorder is characterized by compulsive drug-seeking that persists long into abstinence. Work using rodent models of cocaine addiction has found evidence for reversal learning deficits 21 days after non-contingent cocaine administration and 60 days after self-administration. Here we sought to determine if a deficit in reversal learning is present 3–4 weeks after cessation of cocaine self-administration, when relapse to cocaine-seeking is robust. Conversely, we hypothesized that reversal learning training would protect against relapse, similar to other forms of environmental enrichment. MethodsMale rats underwent short access (ShA, 2 h/10d) or long access (LgA, 1 h/7d then 6 h/10d) cocaine self-administration, followed by 21–29 days of abstinence. During abstinence, a subset of rats underwent training in a plus-maze that required an egocentric strategy to earn a sucrose reward. Following response acquisition and retention, the ability to reverse the spatial navigation strategy was tested. ResultsTotal trials to criteria and total errors made did not differ between the groups during response acquisition, retention, or reversal. On the first reversal test, ShA rats performed better than LgA and control rats. ShA rats’ performance worsened over time. There were no effects of cognitive training or length of cocaine access on context-primed relapse of cocaine-seeking. ConclusionsThe present data indicate that perhaps LgA cocaine self-administration does not produce adaptations to regions mediating context-primed relapse as it does for cocaine and cocaine-associated cue-induced reinstatement of drug-seeking. A time-dependent deficit in reversal learning was found only in ShA rats. Reversal learning training did not protect against cocaine relapse.

Serious games in cognitive rehabilitation of spatial navigation impairment

Stroke patients often report navigation problems (29%). Navigation impairments have a profound impact on the quality of life, as patients experience spatial anxiety, limited mobility, and reduced autonomy. Yet, no standardized rehabilitation training is currently available. The aim of this study is to develop a rehabilitation training for navigation impaired stroke patients in the form of a serious game. Impairments often affect spatial abilities in either the egocentric (route knowledge) or allocentric (survey knowledge) domain. Patients with impairments in the allocentric domain will receive a egocentric training game and vice versa. The goal of the training is to aid patients in the development of compensatory navigation strategies. To this end, 3 exercises in 3D virtual environments are provided in each version of the application. Gaming principles are implemented to increase a patient's motivation, introduce dynamic difficulty levels, provide feedback and to allow for unsupervised training. The feasibility of the training was investigated in a study with 86 healthy participants. Navigation strategy and abilities were assessed in pre and post-training sessions. Based on their pre-training strategy, participants played either the egocentric training ( n = 21) or the allocentric training ( n = 22) version of the game. Participants engaged in 4 training sessions over a period of 2–3 weeks. Participants in the control conditions ( n = 43) did not play the game. Results show that 42.86% of participants in the egocentric training condition adapted an egocentric strategy after the training. The percentage of participants that changed strategy after using the allocentric training, 13.63%, was comparable to that of the control groups 16.23%. We conclude that the rehabilitation training successfully induced strategy change. However, in a healthy population, strategy change was limited to the egocentric domain. Future research is needed to determine the effect of the training in a patient population.

Assessment of Topographic Memory in Mice in a Complex Environment Using the Hamlet Test.

Here we provide instructions to measure topographic memory in mice using the Hamlet test, a complex environment. The apparatus mimics a small hamlet with a central agora and five houses, which are functionalized since mice can drink, eat pellets, hide within a small maze, run in an activity wheel, or interact with a stranger mouse behind a grid. The houses are interconnected through a network of streets in a five-arm star shape, and a video tracking system takes information from the activity in each house or follows a single mouse by trajectometry. Training the mice in the Hamlet, in groups for several hours per day over several days or weeks, allows consolidation of topographic memory (i.e., route learning involving both allocentric and egocentric strategies). Analysis of topographic memory can be performed a posteriori in a probe test by depriving mice of water or food and measuring their ability to efficiently reach the "eat" or "drink" house. Control groups include mice tested in non-deprived condition and mice naïve to the Hamlet and tested in deprived or non-deprived conditions. The present article details the apparatus, procedures, and protocols that can be used to reliably habituate mice in this complex environment and measure topographic memory. © 2018 by John Wiley & Sons, Inc.

The effect of age, sex and gonadectomy on dogs’ use of spatial navigation strategies

In this study we assessed the effect of sex and gonadectomy on the type of spatial strategy (allocentric or egocentric) preferentially used by dogs in the acquisition of a navigation task and their ability to resort to the non-preferred strategy. Fifty-six dogs were involved in the study, divided in four equally sized groups based on sex and gonadectomy. Dogs initially underwent a learning phase, where they entered a plus-shaped maze from one arm and had to learn the position of a food bowl, which was placed in one of the lateral arms. The task could be achieved by relying on an either egocentric (i.e. learning to turn left or right) or allocentric strategy (i.e. using the external cues provided within the maze as a reference the position of the baited bowl). Following training, dogs were let in the maze from the entrance opposite to the one used in the learning phase, so that use of an egocentric strategy would lead them to search for food in one arm, while using an allocentric strategy would lead them into the opposite arm. Dogs’ choices were used to determine their preferred strategy. In the last training phase, we assessed dogs’ ability to resort to their non-preferred strategy to find the baited food bowl, by removing external cues and placing the baited bowl always at the same side of the dog, for subjects deemed as allocentric, and by keeping external cues and placing the baited bowl in a constant location relative to the cues, for dogs deemed as egocentric. No effect of sex was found on strategy preference, but ovariectomized females were significantly more likely to prefer an egocentric strategy, implying a role of ovarian hormones in biasing navigation strategies. The probability of resorting to the non-preferred strategy increased with aging in females and decreased in males. The higher requirement to cope with unpredictable environments during dispersal may support a predisposition to flexibly use different sources of information in younger males. By contrast, experience may be needed by females to reach the same proficiency, thereby justifying the increase in flexibility with ageing. In addition to increasing our knowledge about navigation, these results highlight effects of sex and ovariectomy on dog cognition, with potentially important implications regarding the management of dogs in different fields.

Missing the egocentric spatial reference: a blank on the map.

Egocentric (self-centered) and allocentric (viewpoint independent) representations of space are essential for spatial navigation and wayfinding. Deficits in spatial memory come with age-related cognitive decline, are marked in mild cognitive impairment (MCI) and Alzheimer's disease (AD), and are associated with cognitive deficits in autism. In most of these disorders, a change in the brain areas engaged in the spatial reference system processing has been documented. However, the spatial memory deficits observed during physiological and pathological aging are quite different. While patients with AD and MCI have a general spatial navigation impairment in both allocentric and egocentric strategies, healthy older adults are particularly limited in the allocentric navigation, but they can still count on egocentric navigation strategy to solve spatial tasks. Therefore, specific navigational tests should be considered for differential diagnosis between healthy and pathological aging conditions. Finally, more research is still needed to better understand the spatial abilities of autistic individuals.

Fluid network dynamics in the prefrontal cortex during multiple strategy switching

Coordinated shifts of neuronal activity in the prefrontal cortex are associated with strategy adaptations in behavioural tasks, when animals switch from following one rule to another. However, network dynamics related to multiple-rule changes are scarcely known. We show how firing rates of individual neurons in the prelimbic and cingulate cortex correlate with the performance of rats trained to change their navigation multiple times according to allocentric and egocentric strategies. The concerted population activity exhibits a stable firing during the performance of one rule but shifted to another neuronal firing state when a new rule is learnt. Interestingly, when the same rule is presented a second time within the same session, neuronal firing does not revert back to the original neuronal firing state, but a new activity-state is formed. Our data indicate that neuronal firing of prefrontal cortical neurons represents changes in strategy and task-performance rather than specific strategies or rules.

The effect of Alzheimer's disease on spatial navigation strategies

Hippocampal and basal forebrain (BF) atrophy is associated with allocentric navigation impairment in Alzheimer's disease (AD) and may lead to recruitment of compensatory navigation strategies. We examined navigation strategy preference, its association with allocentric navigation, and the role of hippocampal and BF volumes in this association in early clinical stages of AD. Sixty nine participants—amnestic mild cognitive impairment (aMCI) due to AD (n = 28), AD dementia (n = 21), and cognitively normal (CN) older adults (n = 20)—underwent virtual Y-maze strategy assessment, real-space navigation testing, cognitive assessment, and hippocampal and BF volumetry. Preference for egocentric over allocentric strategy increased with AD severity (aMCI: 67% vs. 33%; dementia: 94% vs. 6%), which contrasted with preference in the CN group (39% vs. 61%). Those with aMCI who preferred egocentric strategy had worse allocentric navigation. Among those with aMCI, hippocampal and BF atrophy explained up to 25% of the association between strategy preference and allocentric navigation. The preference for egocentric strategy in AD may reflect recruitment of compensatory extrahippocampal navigation strategies as adaptation to hippocampal and BF neurodegeneration.

Sex differences in dogs' social learning of spatial information.

We used a modified version of the Do as I Do paradigm to investigate dogs' preference and flexibility in the acquisition of different types of spatial information in social learning situations. When required to match the location of the demonstration, dogs (N=16) preferentially relied on allocentric information, i.e., the relationship between the location of the demonstration and the various objects surrounding it. However, when allocentric cues were inadequate to solve the task, dogs learned to rely on egocentric information, i.e., the direction-left/right-taken by the human demonstrator. The ease of resorting to the non-preferred egocentric strategy was sex-dependent with males acquiring the egocentric strategy in fewer trials than females. This study shows that dogs rely preferentially on allocentric cues when recalling socially acquired spatial information. However, they are impressively flexible in switching to egocentric strategies according to the task requirements. Whether preference for the allocentric strategy in processing spatial information is embedded in the nature of social learning or restricted to our paradigm is an open question. This study also supports the idea that sex differences in cognitive domains are widespread among mammals and calls for further investigations aimed at shedding light on the evolution, function and mechanisms of such differences.

Partial lesion of the nigrostriatal dopamine pathway in rats impairs egocentric learning but not spatial learning or behavioral flexibility.

Degeneration of the nigrostriatal dopaminergic system in Parkinson's disease (PD) causes motor dysfunction and cognitive impairment, but the etiology of the cognitive deficits remains unclear. The present study investigated the behavioral effects of partial lesions of the nigrostriatal dopamine (DA) pathway. Rats received bilateral infusions of either 6-hydroxydopamine (6-OHDA) or vehicle into the dorsolateral striatum and were tested in spatial and procedural learning tasks. Compared with intact rats, DA-depleted rats were impaired when the first task they learned required egocentric responses. Intact rats that received prior training on a spatial task were impaired while learning a subsequent body-turn task, suggesting that prior spatial training may compete with egocentric learning in intact but not DA-depleted rats. Spatial discrimination, reversal learning, and switching between allocentric and egocentric strategies were similar in both groups. The results suggest that DA loss that is not associated with gross motor pathology temporarily impairs egocentric, but not allocentric, learning or subsequent behavioral flexibility. (PsycINFO Database Record

Restructuring the navigational field: individual predisposition towards field independence predicts preferred navigational strategy.

To successfully navigate within an environment, individuals have to organize the spatial information in terms of salient landmarks, paths and general layout of the navigational environment. They may differ in the strategy they adopt to orientate themselves, with some individuals preferring to use salient landmarks (landmark spatial style, L-SS), others preferring to plan routes or paths through an egocentric strategy in which landmarks are connected with each other (route spatial style, R-SS) and others still create a global map-like configuration of the environment regardless of their own position in the environment (survey spatial style, S-SS). Here, we assessed whether Field independence (FI), that is the extent to which the individual perceives part of a field as discrete from the surrounding field rather than embedded in the field, predicted the individual's spatial style. We assessed the individual's spatial style using the spatial cognitive style test (SCST) and measured FI using the group embedded figure test (GEFT). We found that FI predicted general spatial ability, with a higher level of FI being associated with better performances on the SCST. Also, Field-independent individuals showed a marked preference for an S-SS. These results suggest that a higher level of FI is associated with better performance on higher level spatial tasks (i.e. R-SS and S-SS) that is tasks requiring individuals to restructure the "navigational field" according to the navigational goal. The results also suggest that a higher level of FI makes individuals more prone to use a global and complex map-like representation of the environment.

Deletion of the serotonin receptor type 7 disrupts the acquisition of allocentric but not egocentric navigation strategies in mice

Spatial navigation is achieved through both egocentric (body-centered) and allocentric (externally-centered) strategies but decline with age, especially allocentric strategies. A better understanding of the neurobiological mechanisms underlying these strategies would allow the development of new treatments to mitigate this deterioration. Among them, the modulation of 5-HT7 receptor (5-HT7R) may constitute a potential strategy. Indeed, this receptor is known to play a role in spatial navigation, however its precise role in egocentric and allocentric strategies remains unclear. Here, we first examined the effect of 5-HT7 genetic invalidation (knock-out (KO) mice) in two versions of a water cross-maze task in which only egocentric or allocentric strategies were efficient to solve the task. Our results demonstrated that KO mice are able to learn an allocentric strategy. However, contrary to wild-type mice (WT mice), the acquisition rate was slower compared to the task requiring the acquisition of an egocentric strategy. Mice were then trained in a third version of the water maze, allowing the use of both egocentric and allocentric strategies. When facing conflicting spatial information, both KO and WT mice preferentially used an egocentric strategy. However, only WT mice displayed a greater latency to achieve the task. This suggests that WT mice are able to learn both information in parallel, but not KO mice (i.e. only learning an egocentric strategy). Altogether, these results provide evidence for the essential role of the 5HT7R in the acquisition of an allocentric strategy and in the ability to learn concomitantly both strategies.

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

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

Detour Behavior of Mice Trained with Transparent, Semitransparent and Opaque Barriers.

Detour tasks are commonly used to study problem solving skills and inhibitory control in canids and primates. However, there is no comparable detour test designed for rodents despite its significance for studying the development of executive skills. Furthermore, mice offer research opportunities that are not currently possible to achieve when primates are used. Therefore, the aim of the study was to translate the classic detour task to mice and to compare obtained data with key findings obtained previously in other mammals. The experiment was performed with V-shaped barriers and was based on the water escape paradigm. The study showed that an apparently simple task requiring mice to move around a small barrier constituted in fact a challenge that was strongly affected by the visibility of the target. The most difficult task involved a completely transparent barrier, which forced the mice to resolve a conflict between vision and tactile perception. The performance depended both on the inhibitory skills and on previous experiences. Additionally, all mice displayed a preference for one side of the barrier and most of them relied on the egocentric strategy. Obtained results show for the first time that the behavior of mice subjected to the detour task is comparable to the behavior of other mammals tested previously with free-standing barriers. This detailed characterization of the detour behavior of mice constitutes the first step toward the substitution of rodents for primates in laboratory experiments employing the detour task.

Optimal switching between geocentric and egocentric strategies in navigation.

Animals use a combination of egocentric navigation driven by the internal integration of environmental cues, interspersed with geocentric course correction and reorientation. These processes are accompanied by uncertainty in sensory acquisition of information, planning and execution. Inspired by observations of dung beetle navigational strategies that show switching between geocentric and egocentric strategies, we consider the question of optimal reorientation rates for the navigation of an agent moving along a preferred direction in the presence of multiple sources of noise. We address this using a model that takes the form of a correlated random walk at short time scales that is punctuated by reorientation events leading to a biased random walks at long time scales. This allows us to identify optimal alternation schemes and characterize their robustness in the context of noisy sensory acquisition as well as performance errors linked with variations in environmental conditions and agent–environment interactions.

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

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.

Subtle alterations in memory systems and normal visual attention in the GAERS model of absence epilepsy

Objective: Even if considered benign, absence epilepsy may alter memory and attention, sometimes subtly. Very little is known on behavior and cognitive functions in the Genetic Absence Epilepsy Rats from Strasbourg (GAERS) model of absence epilepsy. We focused on different memory systems and sustained visual attention, using Non Epileptic Controls (NECs) and Wistars as controls. Methods: A battery of cognitive/behavioral tests was used. The functionality of reference, working, and procedural memory was assessed in the Morris water maze (MWM), 8-arm radial maze, T-maze and/or double-H maze. Sustained visual attention was evaluated in the 5-choice serial reaction time task. Results: In the MWM, GAERS showed delayed learning and less efficient working memory. In the 8-arm radial maze and T-maze tests, working memory performance was normal in GAERS, although most GAERS preferred an egocentric strategy (based on proprioceptive/kinesthetic information) to solve the task, but could efficiently shift to an allocentric strategy (based on spatial cues) after protocol alteration. Procedural memory and visual attention were mostly unimpaired. Significance: Absence epilepsy has been associated with some learning problems in children. In GAERS, the differences in water maze performance (slower learning of the reference memory task and weak impairment of working memory) and in radial arm maze strategies suggest that cognitive alterations may be subtle, task-specific, and that normal performance can be a matter of strategy adaptation. Altogether, these results strengthen the “face validity” of the GAERS model: in humans with absence epilepsy, cognitive alterations are not easily detectable, which is compatible with subtle deficits.

Individual differences in perception and control of walking direction

INTRODUCTION: There exists an abundant literature on navigation strategies for the visual guidance of goal-directed locomotion. Two main strategies have been documented: the optic flow strategy (OF) and the egocentric direction strategy (ED). OF is assumed to be mainly used when optic flow is densely structured (Harris and Carre, 2001; Wilkie and Wann, 2003), whereas ED would dominate when optical structure is reduced (Rushton et al., 1998; Harris and Bonas, 2002). Less is known about how one particular strategy is exploited depending upon the perceptual and motor history of each individual or upon the individual weighting of sensory information. Inter-individual differences have been found in the perception of self-rotation (Bruggeman et al., 2009) and reported, though not specifically investigated, in visually guided locomotion (Turano et al. 2005; Rusthon et al. 1998). In the present study, we aimed at examining the navigation strategy preferentially used while walking towards a visible goal. METHOD: 27 participants, from 22 to 44 years old (11 women, 16 men), participated in the study. They were asked to walk on a treadmill toward a virtual target, while optic flow was either deviated 10° to the right of actual walking direction, or not deviated. Targets were localised straight ahead, or 20° to the left or right. Heading Error was computed as the difference between instantaneous target direction and walking direction. K-means clustering method was used to examine whether heading distribution could be decomposed into participants relying on OF (Heading Error = OF deviation) and participants relying on ED (No Heading Error). RESULTS: Results showed a large variability in the magnitude of OF's influence, independently of saliency and availability of visual structure. CONCLUSION: There exists important inter-individual variability in the perception and control of locomotion, with individuals forming a continuum, rather than distinct groups, from OF to ED. Meeting abstract presented at VSS 2015. Language: en

Security and Spatial Searching Strategies. the Comparison of Spatial Abilities and Strategies in Anxiety-secure Dimension.

Introduction The success of orientation is influenced not only by spatial abilities but also by spatial orientation strategies. We measured the efficiency of spatial memory with traditional objetive spatial exercises. Objectives We focused on the relation between spatial abilities, strategies and security. We compared the learning time in CGA and the exploration strategies with spatial memory, as well as with the egocentric and allocentric dominant strategies in Lawton navigation strategy questionnaire. Aims We searched for egocentric and allocentric spatial navigation strategies which influence on the information processing and agoraphobic fears. Methods Computer Generated Arena (CGA), which simulates the spatial situation of Morris Water Maze (MWM). Corsi Block Task (Corsi, 1972), Block Design (Kohs, 1923), Lawton Navigation Strategy Questionnaire (Lawton, 1996). Participants: 77 university students, 54 women and 23 men, average age 22,4 years. Results The variable of the learning in CGA, in the Block Design and in the Corsi Block strongly correlated with each other. The spatial construction ability strongly correlated with the allocentric strategies, and the spatial security with the spatial memory. With linear regression in CGA 10th trial, the more complex orientation strategies explain the time of finding the target. The strategy of wayfinding had a strong explanation power too. By females the performance is more sensitive to anxiety temperament and agoraphobic level. Consequences Spatial learning was influenced not only by memory but also by learning strategies. The secure object relations correlated with the use of more developed allocentric strategies.

Sequential egocentric navigation and reliance on landmarks in Williams syndrome and typical development.

Visuospatial difficulties in Williams syndrome (WS) are well documented. Recently, research has shown that spatial difficulties in WS extend to large-scale space, particularly in coding space using an allocentric frame of reference. Typically developing (TD) children and adults predominantly rely on the use of a sequential egocentric strategy to navigate a large-scale route (retracing a sequence of left–right body turns). The aim of this study was to examine whether individuals with WS are able to employ a sequential egocentric strategy to guide learning and the retracing of a route. Forty-eight TD children, aged 5, 7, and 9 years and 18 participants with WS were examined on their ability to learn and retrace routes in two (6-turn) virtual environment mazes (with and without landmarks). The ability to successfully retrace a route following the removal of landmarks (use of sequential egocentric coding) was also examined. Although in line with TD 5-year-olds when learning a route with landmarks, individuals with WS showed significantly greater detriment when these landmarks were removed, relative to all TD groups. Moreover, the WS group made significantly more errors than all TD groups when learning a route that never contained landmarks. On a perceptual view-matching task, results revealed a high level of performance across groups, indicative of an ability to use this visual information to potentially aid navigation. These findings suggest that individuals with WS rely on landmarks to a greater extent than TD children, both for learning a route and for retracing a recently learned route. TD children, but not individuals with WS, were able to fall back on the use of a sequential egocentric strategy to navigate when landmarks were not present. Only TD children therefore coded sequential route information simultaneously with landmark information. The results are discussed in relation to known atypical cortical development and perceptual-matching abilities in WS.

Context influences spatial frames of reference in bonobos (Pan paniscus)

Primates must solve complex spatial problems when foraging, such as finding patchy resources and navigating between different locations. However, the nature of the cognitive representations supporting these types of behaviors is currently unclear. In humans, there has been great debate concerning the relative importance of egocentric representations (which are viewer-dependent) versus allocentric representations (which are based on aspects of the external environment). Comparative studies of nonhuman apes can illuminate which aspects of human spatial cognition are shared with other primates, versus which aspects are unique to our lineage. The current studies therefore examined spatial cognitive development in one of our closest living relatives, bonobos (Pan paniscus) across contexts. The first study assessed how younger bonobos encode locations in a place-response task in which apes first learn that one of two locations is consistently baited with a reward, and then must approach the two locations from a flipped perspective. The second study examined how a larger age sample of bonobos responded to a spatial relations task in which they first experience that one location is baited, and then can generalize this learning to a new set of targets. Results indicated that while bonobos exhibited a predominantly allocentric strategy in the first study, they consistently exhibited an egocentric strategy in the second. Together, these results show that bonobos can use both strategies to encode spatial information, and illuminate the complementary contributions to cognition made by egocentric and allocentric representations.