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How can the interactive mode of a map be optimized to facilitate efficient positioning and improve cognitive efficiency? This paper addresses this crucial aspect of map design. It explores the impact of spatial reference frames, map dimensionality, and navigation modes on spatial orientation efficiency, as well as their interactions, through empirical eye-movement experiments. The results demonstrate the following: (1) When using a 2D fixed map in an allocentric reference frame, participants exhibit a high correct rate, a low cognitive load, and a short reaction time. In contrast, when operating within an egocentric reference frame using a 2D rotating map, participants demonstrate a higher correct rate, a reduced cognitive load, and a quicker reaction time. (2) The simplicity of 2D maps, despite their reduced authenticity compared to 3D maps, diminishes users’ cognitive load and enhances positioning efficiency. (3) The fixed map aligns more closely with the cognitive habits of participants in the allocentric reference frame, while the rotating map corresponds better to the cognitive habits of participants in the egocentric reference frame, thereby improving their cognitive efficiency. This study offers insights that can inform the optimization design of spatial orientation efficiency.

Successful movement depends on an accurate sense of one's location within a particular environment. Neuroscientists distinguish self-centered and world-centered navigation and have been searching for a brain region where all ingredients of navigation come together. As rats foraged in an open field, LaChance et al. recorded activity from single neurons in an area called the postrhinal cortex. The authors found a population of cells that transform an animal's immediate sensory perception of its environment into a spatial map. This map is markedly different from the high-level representations observed in hippocampal place cells or entorhinal grid cells, but it is very flexible and is likely to provide the necessary building blocks for creating higher-level representations. Science , this issue p. eaax4192 Neurons in the rat postrhinal cortex provide a template for the formation of high-level topographic spatial maps. A topographic representation of local space is critical for navigation and spatial memory. In humans, topographic spatial learning relies upon the parahippocampal cortex, damage to which renders patients unable to navigate their surroundings or develop new spatial representations. Stable spatial signals have not yet been observed in its rat homolog, the postrhinal cortex. We recorded from single neurons in the rat postrhinal cortex whose firing reflects an animal’s egocentric relationship to the geometric center of the local environment, as well as the animal’s head direction in an allocentric reference frame. Combining these firing correlates revealed a population code for a stable topographic map of local space. This may form the basis for higher-order spatial maps such as those seen in the hippocampus and entorhinal cortex.

BackgroundTopographical disorientation (TD) refers to a particular condition which determines the loss of spatial orientation, both in new and familiar environments. TD and spatial memory impairments occur relatively early as effect of cognitive decline in aging, even in prodromal stages of dementia, namely mild cognitive impairment (MCI).Aims(a) To show that components linked to the recall of familiar spatial knowledge are relatively spared with respect to the learning of unfamiliar ones in normal aging, while they are not in MCI, and (b) to investigate gender differences for their impact on egocentric and allocentric frames of reference.MethodForty young participants (YC), 40 healthy elderly participants (HE), 40 elderly participants with subjective memory complaints (SMC), and 40 elderly with probable MCI were administered with egocentric and allocentric familiar tasks, based on the map of their hometown, and with egocentric and allocentric unfamiliar tasks, based on new material to be learned. A series of general linear models were used to analyze data.ResultsNo group differences were found on egocentric task based on familiar information. MCI performed worse than the other groups on allocentric tasks based on familiar information (YC = HE = SMC > MCI). Significant differences emerged between groups on egocentric and allocentric tasks based on unfamiliar spatial information (YC > HE = SMC > MCI). A gender difference was found, favoring men on allocentric unfamiliar task.ConclusionFamiliarity of spatial memory traces can represent a protective factor for retrospective components of TD in normal aging. Conversely, using newly learned information for assessment may lead to overestimating TD severity.

Successful navigation relies on reciprocal transformations between spatial representations in world-centered (allocentric) and self-centered (egocentric) frames of reference. The neural basis of allocentric spatial representations has been extensively investigated with grid, border, and head-direction cells in the medial entorhinal cortex (MEC) forming key components of a ‘cognitive map’. Recently, egocentric spatial representations have also been identified in several brain regions, but evidence for the coexistence of neurons encoding spatial variables in each reference frame within MEC is so far lacking. Here, we report that allocentric and egocentric spatial representations are both present in rodent MEC, with neurons in deeper layers representing the egocentric bearing and distance towards the geometric center and / or boundaries of an environment. These results demonstrate a unity of spatial coding that can guide efficient navigation and suggest that MEC may be one locus of interactions between egocentric and allocentric spatial representations in the mammalian brain. Successful navigation relies on reciprocal transformation between different reference frames. Here the authors report egocentric representations of the angle and distance to the boundaries and center of the environment in rodent medial entorhinal cortex, previously known to contain only allocentric spatial representations.

In general, strategies for spatial navigation could employ one of two spatial reference frames: egocentric or allocentric. Notwithstanding intuitive explanations, it remains unclear however under what circumstances one strategy is chosen over another, and how neural representations should be related to the chosen strategy. Here, we first use a deep reinforcement learning model to investigate whether a particular type of navigation strategy arises spontaneously during spatial learning without imposing a bias onto the model. We then examine the spatial representations that emerge in the network to support navigation. To this end, we study two tasks that are ethologically valid for mammals—guidance, where the agent has to navigate to a goal location fixed in allocentric space, and aiming, where the agent navigates to a visible cue. We find that when both navigation strategies are available to the agent, the solutions it develops for guidance and aiming are heavily biased towards the allocentric or the egocentric strategy, respectively, as one might expect. Nevertheless, the agent can learn both tasks using either type of strategy. Furthermore, we find that place-cell-like allocentric representations emerge preferentially in guidance when using an allocentric strategy, whereas egocentric vector representations emerge when using an egocentric strategy in aiming. We thus find that alongside the type of navigational strategy, the nature of the task plays a pivotal role in the type of spatial representations that emerge.

Egocentric encoding is a well-known property of brain areas along the dorsal pathway. Different to previous experiments, which typically only demanded egocentric spatial processing during movement preparation, we designed a task where two male rhesus monkeys memorized an on-the-object target position and then planned a reach to this position after the object re-occurred at variable location with potentially different size. We found allocentric (in addition to egocentric) encoding in the dorsal stream reach planning areas, parietal reach region and dorsal premotor cortex, which is invariant with respect to the position, and, remarkably, also the size of the object. The dynamic adjustment from predominantly allocentric encoding during visual memory to predominantly egocentric during reach planning in the same brain areas and often the same neurons, suggests that the prevailing frame of reference is less a question of brain area or processing stream, but more of the cognitive demands. The neural basis of spatial localization is poorly understood. Here the authors showed that when planning a reach towards an object, neural coding in the frontoparietal network dynamically changes between allocentric and egocentric spatial reference frames where the transition is controlled by task demands.

Hippocampal place cells are influenced by both self-motion (idiothetic) signals and external sensory landmarks as an animal navigates its environment. To continuously update a position signal on an internal ‘cognitive map’, the hippocampal system integrates self-motion signals over time, a process that relies on a finely calibrated path integration gain that relates movement in physical space to movement on the cognitive map. It is unclear whether idiothetic cues alone, such as optic flow, exert sufficient influence on the cognitive map to enable recalibration of path integration, or if polarizing position information provided by landmarks is essential for this recalibration. Here, we demonstrate both recalibration of path integration gain and systematic control of place fields by pure optic flow information in freely moving rats. These findings demonstrate that the brain continuously rebalances the influence of conflicting idiothetic cues to fine-tune the neural dynamics of path integration, and that this recalibration process does not require a top-down, unambiguous position signal from landmarks. Using a closed-loop virtual reality system, the authors show that optic flow cues can causally drive and recalibrate the hippocampal place cell system in the absence of an absolute spatial reference frame defined by external landmarks.

Neurons represent spatial information in diverse reference frames, but it remains unclear whether neural reference frames change with task demands and whether these changes can account for behavior. In this study, we examined how neurons represent the direction of a moving object during self-motion, while monkeys switched, from trial to trial, between reporting object direction in head- and world-centered reference frames. Self-motion information is needed to compute object motion in world coordinates but should be ignored when judging object motion in head coordinates. Neural responses in the ventral intraparietal area are modulated by the task reference frame, such that population activity represents object direction in either reference frame. In contrast, responses in the lateral portion of the medial superior temporal area primarily represent object motion in head coordinates. Our findings demonstrate a neural representation of object motion that changes with task requirements.Sasaki et al. demonstrate that neurons in the macaque parietal cortex (ventral intraparietal area) flexibly represent object motion in either a head-centered or world-centered reference frame depending on the requirements of the task.

Complex sensory information arrives in the brain from an animal’s first-person (‘egocentric’) perspective. However, animals can efficiently navigate as if referencing map-like (‘allocentric’) representations. The postrhinal (POR) and retrosplenial (RSC) cortices are thought to mediate between sensory input and internal maps, combining egocentric representations of physical cues with allocentric head direction (HD) information. Here we show that neurons in the POR and RSC of female Long-Evans rats are tuned to distinct but complementary aspects of local space. Egocentric bearing (EB) cells recorded in square and L-shaped environments reveal that RSC cells encode local geometric features, while POR cells encode a more global account of boundary geometry. Additionally, POR HD cells can incorporate egocentric information to fire in two opposite directions with two oppositely placed identical visual landmarks, while only a subset of RSC HD cells possess this property. Entorhinal grid and HD cells exhibit consistently allocentric spatial firing properties. These results reveal significant regional differences in the neural encoding of spatial reference frames. Whether and how the postrhinal (POR) and retrosplenial (RSC) cortices interact with each other and impact downstream allocentric representations are not fully understood. Here authors present single neuron recordings from freely moving rats exploring different environments to reveal distinct egocentric (self-centered) and allocentric (world-centered) coding frameworks for landmarks and boundaries in interconnected cortical regions.