Hippocampal size predicts rapid learning of a cognitive map in humans

Medial Temporal Lobe Atrophy in Older Adults With Subjective Cognitive Impairments Affects Gait Parameters in the Spatial Navigation Task

Both navigation abilities and gait can be affected by the atrophy in the medial temporal cortex. This study aimed to determine whether navigation abilities could differentiate seniors with and without medial temporal lobe atrophy who complained about their cognitive status. The participants, classified to either the medial temporal atrophy group (n = 23) or the control group (n = 22) underwent neuropsychological assessment and performed a spatial navigation task while their gait parameters were recorded. The study showed no significant differences between the two groups in memory, fluency, and semantic knowledge or typical measures of navigating abilities. However, gait parameters, particularly the propulsion index during certain phases of the navigation task, distinguished between seniors with and without medial temporal lobe lesions. These findings suggest that the gait parameters in the navigation task may be a valuable tool for identifying seniors with cognitive complaints and subtle medial temporal atrophy.

How is GPS used? Understanding navigation system use and its relation to spatial ability

Given how commonly GPS is now used in everyday navigation, it is surprising how little research has been dedicated to investigating variations in its use and how such variations may relate to navigation ability. The present study investigated general GPS dependence, how people report using GPS in various navigational scenarios, and the relationship between these measures and spatial abilities (assessed by self-report measures and the ability to learn the layout of a novel environment). GPS dependence is an individual's perceived need to use GPS in navigation, and GPS usage is the frequency with which they report using different functions of GPS. The study also assessed whether people modulate reported use of GPS as a function of their familiarity with the location in which they are navigating. In 249 participants over two preregistered studies, reported GPS dependence was negatively correlated with objective navigation performance and self-reported sense of direction, and positively correlated with spatial anxiety. Greater reported use of GPS for turn-by-turn directions was associated with a poorer sense of direction and higher spatial anxiety. People reported using GPS most frequently for time and traffic estimation, regardless of ability. Finally, people reported using GPS less, regardless of ability, when they were more familiar with an environment. Collectively these findings suggest that people moderate their use of GPS, depending on their knowledge, ability, and confidence in their own abilities, and often report using GPS to augment rather than replace spatial environmental knowledge.

The format of the cognitive map depends on the structure of the environment

Humans and animals form cognitive maps that allow them to navigate through large-scale environments. Here we address a central unresolved question about these maps: whether they exhibit similar characteristics across all environments, or-alternatively-whether different environments yield different types of maps. To investigate this question, we examined spatial learning in three virtual environments: an open courtyard with patios connected by paths (open maze), a set of rooms connected by corridors (closed maze), and a set of isolated rooms connected only by teleporters (teleport maze). All three environments shared the same underlying topological graph structure. Postlearning tests showed that participants formed representations of the three environments that varied in accuracy, format, and individual variability. The open maze was most accurately remembered, followed by the closed maze, and then the teleport maze. In the open maze, most participants developed representations that reflected the Euclidean structure of the space, whereas in the teleport maze, most participants constructed representations that aligned more closely with a mental model of an interconnected graph. In the closed maze, substantial individual variability emerged, with some participants forming Euclidean representations and others forming graph-like representations. These results indicate that an environment's features shape the quality and nature of the spatial representations formed within it, determining whether spatial knowledge takes a Euclidean or graph-like format. Consequently, experimental findings obtained in any single environment may not generalize to others with different features. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Measuring configural spatial knowledge: Individual differences in correlations between pointing and shortcutting

People use environmental knowledge to maintain a sense of direction in daily life. This knowledge is typically measured by having people point to unseen locations (judgments of relative direction) or navigate efficiently in the environment (shortcutting). Some people can estimate directions precisely, while others point randomly. Similarly, some people take shortcuts not experienced during learning, while others mainly follow learned paths. Notably, few studies have directly tested the correlation between pointing and shortcutting performance. We compared pointing and shortcutting in two experiments, one using desktop virtual reality (VR) (N = 57) and one using immersive VR (N = 48). Participants learned a new environment by following a fixed route and were then asked to point to unseen locations and navigate to targets by the shortest path. Participants' performance was clustered into two groups using K-means clustering. One (lower ability) group pointed randomly and showed low internal consistency across trials in pointing, but were able to find efficient routes, and their pointing and efficiency scores were not correlated. The others (higher ability) pointed precisely, navigated by efficient routes, and their pointing and efficiency scores were correlated. These results suggest that with the same egocentric learning experience, the correlation between pointing and shortcutting depends on participants' learning ability, and internal consistency and discriminating power of the measures. Inconsistency and limited discriminating power can lead to low correlations and mask factors driving human variation. Psychometric properties, largely under-reported in spatial cognition, can advance our understanding of individual differences and cognitive processes for complex spatial tasks.

Individual Differences in Spatial Orientation Modulate Perspective Taking in Listeners

Previous research suggests that individuals exhibit consistent tendencies towards taking their own (an egocentric) or their partner's (an othercentric) spatial perspective. In addition, several factors such as spatial orientation ability, inhibitory control, and social preferences, have been found to mediate these perspective taking tendencies. However, these factors have not been studied together in the context of a single task. The present study explores these individual differences together in spatial perspective taking, using a task of simulated interaction in which listeners can choose to interpret an ambiguous spatial utterance egocentrically or othercentrically. We use a data-driven approach of latent profile analysis to classify participants into subgroups based on their spatial perspective taking tendencies. Our results show that stable subgroups of participants can be identified who differ in their perspective taking tendencies. This behaviour also correlates with a measure of listeners' spatial orientation ability, but not their inhibitory control or social preferences. Our results can be interpreted within a framework that views spatial perspective taking as an embodied cognitive process of a mental reorientation of the self relative to the environment, providing insight on the nature of the mechanisms underlying this operation.

Paving the way to better understand the effects of prolonged spaceflight on operational performance and its neural bases

Space exploration objectives will soon move from low Earth orbit to distant destinations like Moon and Mars. The present work provides an up-to-date roadmap that identifies critical research gaps related to human behavior and performance in altered gravity and space. The roadmap summarizes (1) key neurobehavioral challenges associated with spaceflight, (2) the need to consider sex as a biological variable, (3) the use of integrative omics technologies to elucidate mechanisms underlying changes in the brain and behavior, and (4) the importance of understanding the neural representation of gravity throughout the brain and its multisensory processing. We then highlight the need for a variety of target-specific countermeasures, and a personalized administration schedule as two critical strategies for mitigating potentially adverse effects of spaceflight on the central nervous system and performance. We conclude with a summary of key priorities for the roadmaps of current and future space programs and stress the importance of new collaborative strategies across agencies and researchers for fostering an integrative cross- and transdisciplinary approach from cells, molecules to neural circuits and cognitive performance. Finally, we highlight that space research in neurocognitive science goes beyond monitoring and mitigating risks in astronauts but could also have significant benefits for the population on Earth.

Using a picture (or a thousand words) for supporting spatial knowledge of a complex virtual environment

External representations powerfully support and augment complex human behavior. When navigating, people often consult external representations to help them find the way to go, but do maps or verbal instructions improve spatial knowledge or support effective wayfinding? Here, we examine spatial knowledge with and without external representations in two studies where participants learn a complex virtual environment. In the first study, we asked participants to generate their own maps or verbal instructions, partway through learning. We found no evidence of improved spatial knowledge in a pointing task requiring participants to infer the direction between two targets, either on the same route or on different routes, and no differences between groups in accurately recreating a map of the target landmarks. However, as a methodological note, pointing was correlated with the accuracy of the maps that participants drew. In the second study, participants had access to an accurate map or set of verbal instructions that they could study while learning the layout of target landmarks. Again, we found no evidence of differentially improved spatial knowledge in the pointing task, although we did find that the map group could recreate a map of the target landmarks more accurately. However, overall improvement was high. There was evidence that the nature of improvement across all conditions was specific to initial navigation ability levels. Our findings add to a mixed literature on the role of external representations for navigation and suggest that more substantial intervention-more scaffolding, explicit training, enhanced visualization, perhaps with personalized sequencing-may be necessary to improve navigation ability.

Landmark-dependent Navigation Strategy Declines across the Human Life-Span: Evidence from Over 37,000 Participants

Humans show a remarkable capacity to navigate various environments using different navigation strategies, and we know that strategy changes across the life span. However, this observation has been based on studies of small sample sizes. To this end, we used a mobile app-based video game (Sea Hero Quest) to test virtual navigation strategies and memory performance within a distinct radial arm maze level in over 37,000 participants. Players were presented with six pathways (three open and three closed) and were required to navigate to the three open pathways to collect a target. Next, all six pathways were made available and the player was required to visit the pathways that were previously unavailable. Both reference memory and working memory errors were calculated. Crucially, at the end of the level, the player was asked a multiple-choice question about how they found the targets (i.e., a counting-dependent strategy vs. a landmark-dependent strategy). As predicted from previous laboratory studies, we found the use of landmarks declined linearly with age. Those using landmark-based strategies also performed better on reference memory than those using a counting-based strategy. These results extend previous observations in the laboratory showing a decreased use of landmark-dependent strategies with age.

Evaluating Augmented Reality Landmark Cues and Frame of Reference Displays with Virtual Reality

Daily travel usually demands navigation on foot across a variety of different application domains, including tasks like search and rescue or commuting. Head-mounted augmented reality (AR) displays provide a preview of future navigation systems on foot, but designing them is still an open problem. In this paper, we look at two choices that such AR systems can make for navigation: 1) whether to denote landmarks with AR cues and 2) how to convey navigation instructions. Specifically, instructions can be given via a head-referenced display (screen-fixed frame of reference) or by giving directions fixed to global positions in the world (world-fixed frame of reference). Given limitations with the tracking stability, field of view, and brightness of most currently available head-mounted AR displays for lengthy routes outdoors, we decided to simulate these conditions in virtual reality. In the current study, participants navigated an urban virtual environment and their spatial knowledge acquisition was assessed. We experimented with whether or not landmarks in the environment were cued, as well as how navigation instructions were displayed (i.e., via screen-fixed or world-fixed directions). We found that the world-fixed frame of reference resulted in better spatial learning when there were no landmarks cued; adding AR landmark cues marginally improved spatial learning in the screen-fixed condition. These benefits in learning were also correlated with participants' reported sense of direction. Our findings have implications for the design of future cognition-driven navigation systems.

Explaining World-Wide Variation in Navigation Ability from Millions of People: Citizen Science Project Sea Hero Quest

Navigation ability varies widely across humans. Prior studies have reported that being younger and a male has an advantage for navigation ability. However, these studies have generally involved small numbers of participants from a handful of western countries. Here, we review findings from our project Sea Hero Quest, which used a video game for mobile and tablet devices to test 3.9 million people on their navigation ability, sampling across every nation-state and from 18 to 99 years of age. Results revealed that the task has good ecological validity and across all countries sufficiently sampled (N = 63), age is linked to a near-linear decline in navigation ability from the early 20s. All countries showed a male advantage, but this varied considerably and could be partly predicted by gender inequality. We found that those who reported growing up in a city were on average worse at navigating than those who grew up outside cities and that navigation performance helped identify those at greater genetic risk of Alzheimer's disease. We discuss the advantages and challenges of using a mobile app to study cognition and the future avenues for understanding individual differences in navigation ability arising from this research.

Understanding Differences in Wayfinding Strategies

Navigating to goal locations in a known environment (wayfinding) can be accomplished by different strategies, notably by taking habitual, well-learned routes (response strategy) or by inferring novel paths, such as shortcuts, from spatial knowledge of the environment's layout (place strategy). Human and animal neuroscience studies reveal that these strategies reflect different brain systems, with response strategies relying more on activation of the striatum and place strategies associated with activation of the hippocampus. In addition to individual differences in strategy, recent behavioral studies show sex differences such that men use place strategies more than women, and age differences such that older adults use more response strategies than younger adults. This paper takes a comprehensive multilevel approach to understanding these differences, characterizing wayfinding as a complex information processing task. This analysis reveals factors that affect navigation strategy, including availability of the relevant type of environmental knowledge, momentary access to this knowledge, trade-offs between physical and mental effort in different navigation contexts, and risk taking. We consider how strategies are influenced by the computational demands of a navigation task and by factors that affect the neural circuits underlying navigation. We also discuss limitations of laboratory studies to date and outline priorities for future research, including relating wayfinding strategies to independent measures of spatial knowledge, and studying wayfinding strategies in naturalistic environments.

Individual Differences and Skill Training in Cognitive Mapping: How and Why People Differ

Spatial ability plays important roles in academic learning and everyday activities. A type of spatial thinking that is of particular significance to people's daily lives is cognitive mapping, that is, the process of acquiring, representing, and using knowledge about spatial environments. However, the skill of cognitive mapping shows large individual differences, and the task of spatial orientation and navigation poses great difficulty for some people. In this article, I look at the motivation and findings in the research into spatial knowledge acquisition from an individual differences perspective. I also discuss major implications of the existence of large individual differences, particularly the possibility of improving cognitive mapping by training and adjusting navigation assistance to the wide variations in spatial aptitudes and preferences among people.

Neural substrates of spatial processing and navigation in blindness: An activation likelihood estimation meta-analysis

Even though vision is considered the best suited sensory modality to acquire spatial information, blind individuals can form spatial representations to navigate and orient themselves efficiently in space. Consequently, many studies support the amodality hypothesis of spatial representations since sensory modalities other than vision contribute to the formation of spatial representations, independently of visual experience and imagery. However, given the high variability in abilities and deficits observed in blind populations, a clear consensus about the neural representations of space has yet to be established. To this end, we performed a meta-analysis of the literature on the neural correlates of spatial processing and navigation via sensory modalities other than vision, like touch and audition, in individuals with early and late onset blindness. An activation likelihood estimation (ALE) analysis of the neuroimaging literature revealed that early blind individuals and sighted controls activate the same neural networks in the processing of non-visual spatial information and navigation, including the posterior parietal cortex, frontal eye fields, insula, and the hippocampal complex. Furthermore, blind individuals also recruit primary and associative occipital areas involved in visuo-spatial processing via cross-modal plasticity mechanisms. The scarcity of studies involving late blind individuals did not allow us to establish a clear consensus about the neural substrates of spatial representations in this specific population. In conclusion, the results of our analysis on neuroimaging studies involving early blind individuals support the amodality hypothesis of spatial representations.

Different Profiles of Spatial Navigation Deficits In Alzheimer’s Disease Biomarker-Positive Versus Biomarker-Negative Older Adults With Amnestic Mild Cognitive Impairment

Background

Spatial navigation impairment is a promising cognitive marker of Alzheimer’s disease (AD) that can reflect the underlying pathology.

Objectives

We assessed spatial navigation performance in AD biomarker positive older adults with amnestic mild cognitive impairment (AD aMCI) vs. those AD biomarker negative (non-AD aMCI), and examined associations between navigation performance, MRI measures of brain atrophy, and cerebrospinal fluid (CSF) biomarkers.

Methods

A total of 122 participants with AD aMCI (n = 33), non-AD aMCI (n = 31), mild AD dementia (n = 28), and 30 cognitively normal older adults (CN) underwent cognitive assessment, brain MRI (n = 100 had high-quality images for volumetric analysis) and three virtual navigation tasks focused on route learning (body-centered navigation), wayfinding (world-centered navigation) and perspective taking/wayfinding. Cognitively impaired participants underwent CSF biomarker assessment [amyloid-β1–42, total tau, and phosphorylated tau181 (p-tau181)] and amyloid PET imaging (n = 47 and n = 45, respectively), with a subset having both (n = 19).

Results

In route learning, AD aMCI performed worse than non-AD aMCI (p < 0.001), who performed similarly to CN. In wayfinding, aMCI participants performed worse than CN (both p ≤ 0.009) and AD aMCI performed worse than non-AD aMCI in the second task session (p = 0.032). In perspective taking/wayfinding, aMCI participants performed worse than CN (both p ≤ 0.001). AD aMCI and non-AD aMCI did not differ in conventional cognitive tests. Route learning was associated with parietal thickness and amyloid-β1–42, wayfinding was associated with posterior medial temporal lobe (MTL) volume and p-tau181 and perspective taking/wayfinding was correlated with MRI measures of several brain regions and all CSF biomarkers.

Conclusion

AD biomarker positive and negative older adults with aMCI had different profiles of spatial navigation deficits that were associated with posterior MTL and parietal atrophy and reflected AD pathology.

London taxi drivers: A review of neurocognitive studies and an exploration of how they build their cognitive map of London

Licensed London taxi drivers have been found to show changes in the gray matter density of their hippocampus over the course of training and decades of navigation in London (UK). This has been linked to their learning and using of the "Knowledge of London," the names and layout of over 26,000 streets and thousands of points of interest in London. Here we review past behavioral and neuroimaging studies of London taxi drivers, covering the structural differences in hippocampal gray matter density and brain dynamics associated with navigating London. We examine the process by which they learn the layout of London, detailing the key learning steps: systematic study of maps, travel on selected overlapping routes, the mental visualization of places and the optimal use of subgoals. Our analysis provides the first map of the street network covered by the routes used to learn the network, allowing insight into where there are gaps in this network. The methods described could be widely applied to aid spatial learning in the general population and may provide insights for artificial intelligence systems to efficiently learn new environments.

Hippocampal acidity and volume are differentially associated with spatial navigation in older adults

The hippocampus is negatively affected by aging and is critical for spatial navigation. While there is evidence that wayfinding navigation tasks are especially sensitive to preclinical hippocampal deterioration, these studies have primarily used volumetric hippocampal imaging without considering microstructural properties or anatomical variation within the hippocampus. T1ρ is an MRI measure sensitive to regional pH, with longer relaxation rates reflecting acidosis as a marker of metabolic dysfunction and neuropathological burden. For the first time, we investigate how measures of wayfinding including landmark location learning and delayed memory in cognitively normal older adults (N = 84) relate to both hippocampal volume and T1ρ in the anterior and posterior hippocampus. Regression analyses revealed hippocampal volume was bilaterally related to learning, while right lateralized T1ρ was related to delayed landmark location memory and bilateral T1ρ was related to the delayed use of a cognitive map. Overall, results suggest hippocampal volume and T1ρ relaxation rate tap into distinct mechanisms involved in preclinical cognitive decline as assessed by wayfinding navigation, and laterality influenced these relationships more than the anterior-posterior longitudinal axis of the hippocampus.

Short Digital Spatial Memory Test Detects Impairment in Alzheimer's Disease and Mild Cognitive Impairment

BACKGROUND

Impairment in navigation abilities and object location memory are often seen in early-stage Alzheimer's Disease (AD), yet these constructs are not included in standard neuropsychological assessment. We investigated the differential ability of a short digital spatial memory test in mild AD dementia and mild cognitive impairment (MCI).

METHODS

21 patients with AD dementia (66.9 ± 6.9; 47% female), 22 patients with MCI (69.6 ± 8.3; 46% female) and 21 patients with subjective cognitive decline (SCD) (62.2 ± 8.9; 48% female) from the Amsterdam Dementia Cohort performed the Object Location Memory Test (OLMT), consisting of a visual perception and memory trial, and the Virtual Tübingen (VT) test, consisting of a scene recognition, route continuation, route ordering and distance comparison task. The correlations with other cognitive domains were examined.

RESULTS

Patients with mild AD dementia (Z: -2.51 ± 1.15) and MCI (Z: -1.81 ± 0.92) performed worse than participants with SCD (Z: 0.0 ± 1.0) on the OLMT. Scene recognition and route continuation were equally impaired in patients with AD dementia (Z: -1.14 ± 0.73; Z: -1.44 ± 1.13) and MCI (Z: -1.37 ± 1.25; Z: -1.21 ± 1.07). Route ordering was only impaired in patients with MCI (Z: -0.82 ± 0.78). Weak to moderate correlations were found between route continuation and memory (r(64) = 0.40, p < 0.01), and between route ordering and attention (r(64) = 0.33, p < 0.01), but not for the OLMT.

CONCLUSION

A short digital spatial memory test battery was able to detect object location memory and navigation impairment in patients with mild AD dementia and MCI, highlighting the value of incorporating such a test battery in standard neuropsychological assessment.

A computational cognitive model of judgments of relative direction

In the past several decades, considerable theoretical progress has been made in understanding the role of reference frames in the encoding and retrieval of spatial information about the environment. Many of these insights have come from participants making judgments of relative direction using their memories of spatial layouts. In this task, participants are asked to imagine standing at a given location and facing a certain direction, and to point to a target location. Although this task has been widely and productively used, a computational cognitive model of judgments of relative direction has yet to be introduced. Computational modeling of judgments of relative direction is a critical next step to formulating and testing hypotheses about the cognitive processes involved in establishing and using spatial reference frames. We present an initial attempt to model judgments of relative direction and fit the model to two datasets exhibiting behavioral patterns commonly observed in the spatial memory literature. The model was able to predict many important features of these data, most notably alignment effects. We discuss directions for future modeling efforts.

Hippocampal volume and navigational ability: The map(ping) is not to scale

A critical question regards the neural basis of complex cognitive skill acquisition. One extensively studied skill is navigation, with evidence suggesting that humans vary widely in navigation abilities. Yet, data supporting the neural underpinning of these individual differences are mixed. Some evidence suggests robust structure-behavior relations between hippocampal volume and navigation ability, whereas other experiments show no such correlation. We focus on several possibilities for these discrepancies: 1) volumetric hippocampal changes are relevant only at the extreme ranges of navigational abilities; 2) hippocampal volume correlates across individuals but only for specific measures of navigation skill; 3) hippocampal volume itself does not correlate with navigation skill acquisition; connectivity patterns are more relevant. To explore this third possibility, we present a model emphasizing functional connectivity changes, particularly to extra-hippocampal structures. This class of models arises from the premise that navigation is dynamic and that good navigators flexibly solve spatial challenges. These models pave the way for research on other skills and provide more precise predictions for the neural basis of skill acquisition.

Single-trial regression of spatial exploration behavior indicates posterior EEG alpha modulation to reflect egocentric coding

Learning to navigate uncharted terrain is a key cognitive ability that emerges as a deeply embodied process, with eye movements and locomotion proving most useful to sample the environment. We studied healthy human participants during active spatial learning of room-scale virtual reality (VR) mazes. In the invisible maze task, participants wearing a wireless electroencephalography (EEG) headset were free to explore their surroundings, only given the objective to build and foster a mental spatial representation of their environment. Spatial uncertainty was resolved by touching otherwise invisible walls that were briefly rendered visible inside VR, similar to finding your way in the dark. We showcase the capabilities of mobile brain/body imaging using VR, demonstrating several analysis approaches based on general linear models (GLMs) to reveal behavior-dependent brain dynamics. Confirming spatial learning via drawn sketch maps, we employed motion capture to image spatial exploration behavior describing a shift from initial exploration to subsequent exploitation of the mental representation. Using independent component analysis, the current work specifically targeted oscillations in response to wall touches reflecting isolated spatial learning events arising in deep posterior EEG sources located in the retrosplenial complex. Single-trial regression identified significant modulation of alpha oscillations by the immediate, egocentric, exploration behavior. When encountering novel walls, as well as with increasing walking distance between subsequent touches when encountering novel walls, alpha power decreased. We conclude that these oscillations play a prominent role during egocentric evidencing of allocentric spatial hypotheses.

A computerized spatial orientation test

In three experiments, we compared performance on a paper-based perspective-taking task (the Spatial Orientation Test [SOT]; Hegarty & Waller, 2004) with performance on a computer-based version of the task. The computer-based version automates scoring angular errors, allows for different stimulus orders to be given to each participant, and allows for different testing time limits. In Experiment 1, the two media used different objects and mirror-image stimulus arrays in the two versions to mitigate the effects of memory for specific objects or responses. In Experiments 2 and 3, the two media used identical objects (also in a mirrored arrangement), to provide a more equivalent between-media comparison. We also substituted new objects for objects in the original version that had an inherent front/back (e.g., a car) and/or that were animate; directional or animate objects may add variance that is unrelated to perspective-taking ability. Experiment 3 used clarified instructions and a sample size sufficient to examine relatively small differences between the media as well as sex differences. Overall, the computer-based version produced performance that was similar to that of the paper-based version in terms of the rank-order of the participants. The new computer and paper versions of the SOT also had similar correlations with the Money Road Map test and the Santa Barbara Sense of Direction questionnaire, adding support to the claim that the computerized SOT is tapping into the same skill as the paper-based version. We provide a Java version of the new SOT, along with pdf files of instructions and practice stimuli, on the Open Science Framework website.

Structural abnormalities of cingulate cortex in patients with first-episode drug-naïve schizophrenia comorbid with depressive symptoms

Depressive symptoms are common in patients with first-episode psychosis. However, the neural mechanisms underlying the comorbid depression in schizophrenia are still unknown. The main purpose of this study was to characterize the structural abnormalities of first-episodes drug-naïve (FEDN) schizophrenia comorbid with depression by utilizing both volume-based and surface-based morphometric measurements. Forty-two patients with FEDN schizophrenia and 29 healthy controls were recruited. The 24-item Hamilton Depression Rating Scale (HAMD-24) was administrated to divide all patients into depressive patients (DP) and non-depressive patients (NDP). Compared with NDP, DP had a significantly larger volume and surface area in the left isthmus cingulate cortex and also had a greater volume in the left posterior cingulate cortex. Correlation analysis showed that HAMD total score was positively correlated with the surface area of the left isthmus cingulate and gray matter volume of the left isthmus cingulate cortex. In addition, gray matter volume of the left isthmus cingulate was also correlated with the PANSS general psychopathology or total score. The findings suggest that prominent structural abnormalities of gray matter are mainly concentrated on the cingulate cortex in FEDN schizophrenia patients comorbid with depression, which may contribute to depressive symptoms and psychopathological symptoms.

Hippocampal cells integrate past memory and present perception for the future

The ability to use stored information in a highly flexible manner is a defining feature of the declarative memory system. However, the neuronal mechanisms underlying this flexibility are poorly understood. To address this question, we recorded single-unit activity from the hippocampus of 2 nonhuman primates performing a newly devised task requiring the monkeys to retrieve long-term item-location association memory and then use it flexibly in different circumstances. We found that hippocampal neurons signaled both mnemonic information representing the retrieved location and perceptual information representing the external circumstance. The 2 signals were combined at a single-neuron level to construct goal-directed information by 3 sequentially occurring neuronal operations (e.g., convergence, transference, and targeting) in the hippocampus. Thus, flexible use of knowledge may be supported by the hippocampal constructive process linking memory and perception, which may fit the mnemonic information into the current situation to present manageable information for a subsequent action.

This study reveals that three neuronal operations in the macaque hippocampus combine retrieved memory and incoming perceptual information to construct goal-directed information; this constructive memory process may equip us to use past knowledge flexibly according to the current situation.

Neuroanatomic Correlates of Distance and Direction Processing During Cognitive Map Retrieval

Navigating toward a goal and mentally comparing distances and directions to landmarks are processes requiring reading information off the memorized representation of the environment, that is, the cognitive map. Brain structures in the medial temporal lobe, in particular, are known to be involved in the learning, storage, and retrieval of cognitive map information, which is generally assumed to be in allocentric form, whereby pure spatial relations (i.e., distance and direction) connect locations with each other. The authors recorded functional magnetic resonance imaging activity, while participants were submitted to a variant of a neuropsychological test (the Cognitive Map Reading Test; CMRT) originally developed to evaluate the performance of brain-lesioned patients and in which participants have to compare distances and directions in their mental map of their hometown. Our main results indicated posterior parahippocampal, but not hippocampal, activity, consistent with a task involving spatial memory of places learned a long time ago; left parietal and left frontal activity, consistent with the distributed processing of navigational representations; and, unexpectedly, cerebellar activity, possibly related to the role of the cerebellum in the processing of (here, imaginary) self-motion cues. In addition, direction, but not distance, comparisons elicited significant activation in the posterior parahippocampal gyrus.

Searching for individual determinants of probabilistic cueing in large-scale immersive virtual environments

Large-scale search behaviour is an everyday occurrence, yet its underlying mechanisms are not commonly examined within experimental psychology. Key to efficient search behaviour is the sensitivity to environmental cues that might guide exploration, such as a target appearing with greater regularity in one region than another. Spatial cueing by probability has been examined in visual search paradigms, but the few studies that have addressed its contribution to large-scale search and foraging present contrasting accounts of the conditions under which a cueing effect can be reliably observed. In the present study, participants physically searched a virtual arena by inspecting identical locations until they found the target. The target was always present, although its location was probabilistically defined so that it appeared in the cued hemispace on 80% of trials. In Experiment 1, when participants' starting positions were stable, a probabilistic cueing effect was observed, with a strong bias towards searching the cued side. In Experiment 2, the starting position changed across the experiment, such that the cued region was defined in allocentric co-ordinates only. In this case, a probabilistic cueing effect was not observed across the sample. Analysis of individual differences in Experiment 2 suggests, however, that some participants may have learned the contingency underpinning the target's location, although these differences were unrelated to other tests of visuospatial ability. These results suggest that the ability to learn the likelihood of an item's fixed location when starting from different perspectives is driven by individual differences in other cognitive or perceptual factors.

Current Promises and Limitations of Combined Virtual Reality and Functional Magnetic Resonance Imaging Research in Humans: A Commentary on Huffman and Ekstrom (2019)

Real-world navigation requires movement of the body through space, producing a continuous stream of visual and self-motion signals, including proprioceptive, vestibular, and motor efference cues. These multimodal cues are integrated to form a spatial cognitive map, an abstract, amodal representation of the environment. How the brain combines these disparate inputs and the relative importance of these inputs to cognitive map formation and recall are key unresolved questions in cognitive neuroscience. Recent advances in virtual reality technology allow participants to experience body-based cues when virtually navigating, and thus it is now possible to consider these issues in new detail. Here, we discuss a recent publication that addresses some of these issues (D. J. Huffman and A. D. Ekstrom. A modality-independent network underlies the retrieval of large-scale spatial environments in the human brain. Neuron, 104, 611-622, 2019). In doing so, we also review recent progress in the study of human spatial cognition and raise several questions that might be addressed in future studies.

Landmarks: A solution for spatial navigation and memory experiments in virtual reality

Research into the behavioral and neural correlates of spatial cognition and navigation has benefited greatly from recent advances in virtual reality (VR) technology. Devices such as head-mounted displays (HMDs) and omnidirectional treadmills provide research participants with access to a more complete range of body-based cues, which facilitate the naturalistic study of learning and memory in three-dimensional (3D) spaces. One limitation to using these technologies for research applications is that they almost ubiquitously require integration with video game development platforms, also known as game engines. While powerful, game engines do not provide an intrinsic framework for experimental design and require at least a working proficiency with the software and any associated programming languages or integrated development environments (IDEs). Here, we present a new asset package, called Landmarks, for designing and building 3D navigation experiments in the Unity game engine. Landmarks combines the ease of building drag-and-drop experiments using no code, with the flexibility of allowing users to modify existing aspects, create new content, and even contribute their work to the open-source repository via GitHub, if they so choose. Landmarks is actively maintained and is supplemented by a wiki with resources for users including links, tutorials, videos, and more. We compare several alternatives to Landmarks for building navigation experiments and 3D experiments more generally, provide an overview of the package and its structure in the context of the Unity game engine, and discuss benefits relating to the ongoing and future development of Landmarks.

From repeating routes to planning novel routes: the impact of landmarks and ageing on route integration and cognitive mapping

The integration of intersecting routes is an important process for the formation of cognitive maps and thus successful navigation. Here we present a novel task to study route integration and the effects that landmark information and cognitive ageing have on this process. We created two virtual environments, each comprising five places and one central intersection but with different landmark settings: in the Identical Landmark environment, the intersection contained visually monotonic features whereas the intersection contained visually distinctive features in the Different Landmarks environment. In both environments young and older participants were presented with two short routes that both traversed through the shared intersection. To test route integration, participants were asked to either repeat the learning routes, to navigate the routes from the destination to the starting place or to plan novel routes. As expected, results demonstrate better performance when repeating or retracing routes than when planning novel routes. Performance was better in younger than older participants and in the Different Landmark environment which does not require detailed knowledge of the spatial configuration of all places in the environment. A subgroup of the older participants who performed lower on a screening test for cognitive impairments could not successfully complete the experiment or did not reach the required performance criterion. These results demonstrate that strategically placed landmarks support the integration of route knowledge into spatial representations that allow for goal-dependent flexible navigation behaviour and that earliest signs of atypical cognitive ageing affect this process of route integration.

Medial Prefrontal Cortex Represents the Object-Based Cognitive Map When Remembering an Egocentric Target Location

A cognitive map, representing an environment around oneself, is necessary for spatial navigation. However, compared with its constituent elements such as individual landmarks, neural substrates of coherent spatial information, which consists in a relationship among the individual elements, remain largely unknown. The present study investigated how the brain codes map-like representations in a virtual environment specified by the relative positions of three objects. Representational similarity analysis revealed an object-based spatial representation in the hippocampus (HPC) when participants located themselves within the environment, while the medial prefrontal cortex (mPFC) represented it when they recollected a target object's location relative to their self-body. During recollection, task-dependent functional connectivity increased between the two areas implying exchange of self-location and target location signals between the HPC and mPFC. Together, the object-based cognitive map, whose coherent spatial information could be formed by objects, may be recruited in the HPC and mPFC for complementary functions during navigation, which may generalize to other aspects of cognition, such as navigating social interactions.

Improving cognitive mapping by training for people with a poor sense of direction

The skill of spatial learning and orientation is fundamental in humans and differs widely among individuals. Despite its importance, however, the malleability of this skill through practice has scarcely been studied empirically, in contrast to psychometric spatial ability. Thus, this article examines the possibility of improving the accuracy of configurational understanding of the environment by training. A total of 40 adults with a poor sense of direction participated in the experiment; and were randomly assigned to either a condition in which they received feedback only or a condition in which they additionally practiced allocentric spatial updating. Participants walked one route in each session, once a week for 6 weeks, and conducted spatial tasks designed to assess their knowledge of the route. A total of 20 people with an average sense of direction also participated as a comparison group. Results showed that training in allocentric spatial updating improved the accuracy of direction estimates, although the size of the effect was limited: the improvement was not large enough to equate the performance in the groups with a poor versus average sense of direction. The two groups, however, did not differ in spatial skill in mental rotation or path integration. Feedback was effective for improving accuracy in straight-line distance estimates and sketch maps: repeated trials with feedback led to improved accuracy by the sixth session to a level comparable to the group with an average sense of direction. The results show that flexible translation between viewer-centered and environment-centered representations is difficult and not readily trainable, and provide insights into the nature of individual differences in large-scale environmental cognition.

Does hippocampal volume explain performance differences on hippocampal-dependant tasks?

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Evidence is mixed about whether hippocampal volume affects cognitive task performance.

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This is particularly the case concerning individual differences in healthy people.

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We collected structural MRI data from 217 healthy people.

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They also had widely-varying performance on cognitive tasks linked to the hippocampus.

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In-depth analyses showed little evidence hippocampal volume affected task performance.

Marked disparities exist across healthy individuals in their ability to imagine scenes, recall autobiographical memories, think about the future and navigate in the world. The importance of the hippocampus in supporting these critical cognitive functions has prompted the question of whether differences in hippocampal grey matter volume could be one source of performance variability. Evidence to date has been somewhat mixed. In this study we sought to mitigate issues that commonly affect these types of studies. Data were collected from a large sample of 217 young, healthy adult participants, including whole brain structural MRI data (0.8 mm isotropic voxels) and widely-varying performance on scene imagination, autobiographical memory, future thinking and navigation tasks. We found little evidence that hippocampal grey matter volume was related to task performance in this healthy sample. This was the case using different analysis methods (voxel-based morphometry, partial correlations), when whole brain or hippocampal regions of interest were examined, when comparing different sub-groups (divided by gender, task performance, self-reported ability), and when using latent variables derived from across the cognitive tasks. Hippocampal grey matter volume may not, therefore, significantly influence performance on tasks known to require the hippocampus in healthy people. Perhaps only in extreme situations, as in the case of licensed London taxi drivers, are measurable ability-related hippocampus volume changes consistently exhibited.

Spatial Competence and Brain Plasticity in Congenital Blindness via Sensory Substitution Devices

In congenital blindness (CB), tactile, and auditory information can be reinterpreted by the brain to compensate for visual information through mechanisms of brain plasticity triggered by training. Visual deprivation does not cause a cognitive spatial deficit since blind people are able to acquire spatial knowledge about the environment. However, this spatial competence takes longer to achieve but is eventually reached through training-induced plasticity. Congenitally blind individuals can further improve their spatial skills with the extensive use of sensory substitution devices (SSDs), either visual-to-tactile or visual-to-auditory. Using a combination of functional and anatomical neuroimaging techniques, our recent work has demonstrated the impact of spatial training with both visual to tactile and visual to auditory SSDs on brain plasticity, cortical processing, and the achievement of certain forms of spatial competence. The comparison of performances between CB and sighted people using several different sensory substitution devices in perceptual and sensory-motor tasks uncovered the striking ability of the brain to rewire itself during perceptual learning and to interpret novel sensory information even during adulthood. We discuss here the implications of these findings for helping blind people in navigation tasks and to increase their accessibility to both real and virtual environments.

The Acquisition of Survey Knowledge by Individuals With Down Syndrome

People with Down syndrome often exhibit deficiencies in wayfinding activities, particularly route learning (e.g., Courbois et al., 2013; Davis et al., 2014; Farran et al., 2015). Evidence concerning more sophisticated survey learning has been sparse. In the research reported here, two experiments are reported that evaluated survey learning of youth with DS and typically developing children (TD) matched on mental age. In Experiment 1, participants learned two overlapping routes consisting of three turns each through a virtual environment depicting 9 square city blocks. Following acquisition, they were tested on multiple measures of survey knowledge: finding a shortcut, identifying the direction of landmarks not currently visible from their location in the environment, and recognizing a bird's-eye representation of the overall environment. Under these conditions, which should provide relatively optimal opportunities for survey learning, the participants with DS performed comparably to TD participants matched on non-verbal ability on all of our measures of survey learning. Hence, we concluded that people with DS can acquire some survey knowledge when tasked with learning a small environment and given the opportunity to do so. In Experiment 2, the experimenter navigated participants through a large, relatively complex, virtual environment along a circuitous path, beginning and ending at a target landmark. Then, the participants were placed at a pre-specified location in the environment that they had viewed previously and instructed to navigate to the same target (a door) using the shortest possible path from their current location. They completed the task three times: once after being shown the environment one time, once after three exposures, and once after five exposures. Results indicated that the participants with DS exhibited significantly less skill at identifying the shortcut than did the TD participants, with differences emerging as the number of exposures increased. Participants with DS were also less able to recall landmarks at the end of the experiment. Overall, however, the performance of both groups was relatively poor in both experiments - with the performance of participants with DS being worse as conditions became less optimal. These results were discussed in terms of underlying mechanisms that may account for variations in survey learning as environmental complexity increases.

Probing the invariant structure of spatial knowledge: Support for the cognitive graph hypothesis

We tested four hypotheses about the structure of spatial knowledge used for navigation: (1) the Euclidean hypothesis, a geometrically consistent map; (2) the Neighborhood hypothesis, adjacency relations between spatial regions, based on visible boundaries; (3) the Cognitive Graph hypothesis, a network of paths between places, labeled with approximate local distances and angles; and (4) the Constancy hypothesis, whatever geometric properties are invariant during learning. In two experiments, different groups of participants learned three virtual hedge mazes, which varied specific geometric properties (Euclidean Control Maze, Elastic Maze with stretching paths, Swap Maze with alternating paths to the same place). Spatial knowledge was then tested using three navigation tasks (metric shortcuts on empty ground plane, neighborhood shortcuts with visible boundaries, route task in corridors). They yielded the following results: (a) Metric shortcuts were insensitive to detectable shifts in target location, inconsistent with the Euclidean hypothesis. (b) Neighborhood shortcuts were constrained by visible boundaries in the Elastic Maze, but not in the Swap Maze, contrary to the Neighborhood and Constancy hypotheses. (c) The route task indicated that a graph of the maze was acquired in all environments, including knowledge of local path lengths. We conclude that primary spatial knowledge is consistent with the Cognitive Graph hypothesis. Neighborhoods are derived from the graph, and local distance and angle information is not embedded in a geometrically consistent map.

Negative correlation between grey matter in the hippocampus and caudate nucleus in healthy aging

Neurobiological changes that occur with aging include a reduction in function and volume of the hippocampus. These changes were associated with corresponding memory deficits in navigation tasks. However, navigation can involve different strategies that are dependent on the hippocampus and caudate nucleus. The proportion of people using hippocampus-dependent spatial strategies decreases across the lifespan. As such, the decrease in spatial strategies, and corresponding increase in caudate nucleus-dependent response strategies with age, may play a role in the observed neurobiological changes in the hippocampus. Furthermore, we previously showed a negative correlation between grey matter in the hippocampus and caudate nucleus/striatum in mice, young adults, and in individuals diagnosed with Alzheimer's disease. As such, we hypothesized that this negative relationship between the two structures would be present during normal aging. The aim of the current study was to investigate this gap in the literature by studying the relationship between grey matter in the hippocampus and caudate nucleus of the striatum, in relation to each other and to navigation strategies, during healthy aging. Healthy older adults (N = 39) were tested on the Concurrent Spatial Discrimination Learning Task (CSDLT), a virtual radial task that dissociates between spatial and response strategies. A regression of strategies against structural MRIs showed for the first time in older adults that the response strategy was associated with higher amounts of grey matter in the caudate nucleus. As expected, the spatial strategy correlated with grey matter in the hippocampus, which was negatively correlated with grey matter in the caudate nucleus. Interestingly, a sex difference emerged showing that among older adult response learners, women have the least amount of grey matter in the hippocampus, which is a known risk for Alzheimer's disease. This difference was absent among spatial learners. These results are discussed in the context of the putative protective role of spatial memory against grey matter loss in the hippocampus, especially in women.

Testing Navigation in Real Space: Contributions to Understanding the Physiology and Pathology of Human Navigation Control

Successful navigation relies on the flexible and appropriate use of metric representations of space or topological knowledge of the environment. Spatial dimensions (2D vs. 3D), spatial scales (vista-scale vs. large-scale environments) and the abundance of visual landmarks critically affect navigation performance and behavior in healthy human subjects. Virtual reality (VR)-based navigation paradigms in stationary position have given insight into the major navigational strategies, namely egocentric (body-centered) and allocentric (world-centered), and the cerebral control of navigation. However, VR approaches are biased towards optic flow and visual landmark processing. This major limitation can be overcome to some extent by increasingly immersive and realistic VR set-ups (including large-screen projections, eye tracking and use of head-mounted camera systems). However, the highly immersive VR settings are difficult to apply particularly to older subjects and patients with neurological disorders because of cybersickness and difficulties with learning and conducting the tasks. Therefore, a need for the development of novel spatial tasks in real space exists, which allows a synchronous analysis of navigational behavior, strategy, visual explorations and navigation-induced brain activation patterns. This review summarizes recent findings from real space navigation studies in healthy subjects and patients with different cognitive and sensory neurological disorders. Advantages and limitations of real space navigation testing and different VR-based navigation paradigms are discussed in view of potential future applications in clinical neurology.

The role of the fornix in human navigational learning

Experiments on rodents have demonstrated that transecting the white matter fibre pathway linking the hippocampus with an array of cortical and subcortical structures - the fornix - impairs flexible navigational learning in the Morris Water Maze (MWM), as well as similar spatial learning tasks. While diffusion magnetic resonance imaging (dMRI) studies in humans have linked inter-individual differences in fornix microstructure to episodic memory abilities, its role in human spatial learning is currently unknown. We used high-angular resolution diffusion MRI combined with constrained spherical deconvolution-based tractography, to ask whether inter-individual differences in fornix microstructure in healthy young adults would be associated with spatial learning in a virtual reality navigation task. To efficiently capture individual learning across trials, we adopted a novel curve fitting approach to estimate a single index of learning rate. We found a statistically significant correlation between learning rate and the microstructure (mean diffusivity) of the fornix, but not that of a comparison tract linking occipital and anterior temporal cortices (the inferior longitudinal fasciculus, ILF). Further, this correlation remained significant when controlling for both hippocampal volume and participant gender. These findings extend previous animal studies by demonstrating the functional relevance of the fornix for human spatial learning in a virtual reality environment, and highlight the importance of a distributed neuroanatomical network, underpinned by key white matter pathways, such as the fornix, in complex spatial behaviour.

Heterogeneous correlations between hippocampus volume and cognitive map accuracy among healthy young adults

Marked individual differences in the ability to mentally map our environment are pronounced not only among people of different ages or clinical conditions, but also within healthy young adults. Previous studies have shown that hippocampus size positively correlated with spatial navigation ability in healthy young adults, navigation experts, and patients with hippocampus lesions. However, a recent pre-registered study (Weisberg, Newcombe, & Chatterjee, 2019) with a large sample size (n = 90) did not observe this correlation in healthy young adults. Motivated by evidence that self-report sense of direction (SOD) could have a profound impact on how individuals utilize environmental cues, and that different navigation strategies could have opposite impacts on wayfinding performance in individuals with different cognitive map formation (CMF) abilities, we reanalyzed the publicly available dataset from Weisberg et al.'s study. We tested the influence of participants' SOD and CMF abilities on hippocampal volume-performance relationships. We find evidence that the non-significant correlation could envelop heterogeneous correlations among subgroups of individuals: the correlation between the right posterior hippocampal volume and spatial learning performance is significantly higher among individuals with high spatial ability than individuals with low spatial ability. This pattern of performance was observed for both SOD and CMF moderations of the relationship between hippocampal volume and spatial learning. While our re-analyses are fundamentally exploratory in nature, the new results imply that the relationship between hippocampal volume and spatial learning performance might be more complicated than previously thought.

Developing a Spatial Navigation Screening Tool Sensitive to the Preclinical Alzheimer Disease Continuum

OBJECTIVE

There remains a need for a non-invasive and cost-effective screening measure that could be administered prior to the provision of a lumbar puncture or positron emission tomography scan for the detection of preclinical Alzheimer disease (AD). Previous findings suggest that a hippocampally-based spatial navigation task may be effective for screening individuals for the preclinical AD continuum (i.e., low cerebrospinal fluid (CSF) Aβ42). Unfortunately, this task took 1.5-2 hours to administer, which would be time-prohibitive in a clinical setting. Therefore, the goal of this study was to compare psychometric properties of six spatial navigation-related tasks in order to take the next steps in developing a clinically appropriate screening measure.

METHODS

Psychometric properties (i.e., reliability, diagnostic accuracy, validity) of a modified version of the cognitive mapping task, two binding tasks, a visual perspective taking task, and self- and informant report versions of a questionnaire were examined in a sample of 91 clinically normal (CN) individuals. CSF Aβ42 and ptau181 were available for 30 individuals.

RESULTS

The learning phase of the cognitive mapping task and the self-report questionnaire were sensitive to identifying individuals in the preclinical AD continuum (93% and 87% sensitivity, 60% and 67% specificity, respectively). These two measures also demonstrated good test-retest stability (intraclass correlation coefficients = .719 and .838, respectively) and internal consistency (Cronbach's αs = .825 and .965, respectively).

CONCLUSIONS

These findings suggest that a self-report questionnaire and aspects of a cognitive mapping task may be particularly appropriate for development as screening tools for identifying individuals in the preclinical AD continuum.

Gray matter nuclei damage in acute carbon monoxide intoxication assessed in vivo using diffusion tensor MR imaging

OBJECTIVE

To observe the structural changes of gray matter nuclei in patients with acute carbon monoxide intoxication by diffusion tensor imaging (DTI), quantify the degree of deep gray matter damage in the brain by adopting imaging technology and research the characteristics of the damage and its pertinence with memory and cognitive impairment.

METHODS

Twenty-five patients with acute carbon monoxide intoxication and 25 healthy volunteers matched in sex and age were examined by routine head MRI and diffusion tensor imaging (DTI). Bilateral hippocampus, dater nucleus, thalamus, amygdala, globus pallidus and putamen were taken as regions of interest. The mean diffusion coefficient (MD), anisotropic fraction (FA) and appearance of deep gray matter nucleus in patients with acute carbon monoxide intoxication were analyzed. It found that the change of diffusion coefficient (ADC) and its clinical correlation with cognitive impairment were generated by carbon monoxide intoxication.

RESULTS

Compared with the healthy control group, the FA values of bilateral globus pallidus, hippocampus, dater nucleus and putamen decreased, while the FA values of amygdala and thalamus had no statistical significance; the MD values and ADC values of hippocampus, globus pallidus and putamen increased, while the MD and ADC values of dater nucleus, thalamus and amygdala had no statistical significance, either.

CONCLUSION

DTI is capable of sensitively reflecting the damage of gray matter nuclei caused by acute carbon monoxide intoxication and quantifying the degree of hypoxic brain damage in a certain extent, and may be related to cognitive impairment.

Spatial navigation deficits - overlooked cognitive marker for preclinical Alzheimer disease?

Detection of incipient Alzheimer disease (AD) pathophysiology is critical to identify preclinical individuals and target potentially disease-modifying therapies towards them. Current neuroimaging and biomarker research is strongly focused in this direction, with the aim of establishing AD fingerprints to identify individuals at high risk of developing this disease. By contrast, cognitive fingerprints for incipient AD are virtually non-existent as diagnostics and outcomes measures are still focused on episodic memory deficits as the gold standard for AD, despite their low sensitivity and specificity for identifying at-risk individuals. This Review highlights a novel feature of cognitive evaluation for incipient AD by focusing on spatial navigation and orientation deficits, which are increasingly shown to be present in at-risk individuals. Importantly, the navigation system in the brain overlaps substantially with the regions affected by AD in both animal models and humans. Notably, spatial navigation has fewer verbal, cultural and educational biases than current cognitive tests and could enable a more uniform, global approach towards cognitive fingerprints of AD and better cognitive treatment outcome measures in future multicentre trials. The current Review appraises the available evidence for spatial navigation and/or orientation deficits in preclinical, prodromal and confirmed AD and identifies research gaps and future research priorities.

Cognitive mapping style relates to posterior-anterior hippocampal volume ratio

As London taxi drivers acquire "the knowledge" and develop a detailed cognitive map of London, their posterior hippocampi (pHPC) gradually increase in volume, reflecting an increasing pHPC/aHPC volume ratio. In the mnemonic domain, greater pHPC/aHPC volume ratios in young adults have been found to relate to better recollection ability, indicating that the balance between pHPC and aHPC volumes might be reflective of cross-domain individual differences. Here, we examined participants' self-reported use of cognitive map-based navigational strategies in relation to their pHPC/aHPC hippocampal volume ratio. We find that greater reported cognitive map use was related to significantly greater posterior, relative to anterior, hippocampal volume in two separate samples of young adults. Further, greater reported cognitive map usage correlated with better performance on a self-initiated navigation task. Together, these data help to advance our understanding of differences between aHPC and pHPC and the greater role of pHPC in spatial mapping.

Beyond small-scale spatial skills: Navigation skills and geoscience education

Background

Research examining the relation between spatial skills and the science, technology, engineering and mathematics (STEM) fields has focused on small-scale spatial skills, even though some STEM disciplines—particularly the geography and geoscience (GEO) fields—involve large-scale spatial thinking at the core of their professional training. In Study 1, we compared large-scale navigation skills of experienced geologists with those of experienced psychologists, using a novel virtual navigation paradigm as an objective measure of navigation skills. In Study 2, we conducted a longitudinal study with novice Geographic Information Systems (GIS) students to investigate baseline navigational competence and improvement over the course of an academic semester.

Results

In Study 1, we found that geologists demonstrated higher navigational competence and were more likely to be categorized as integrating separate routes, compared to their non-STEM counterparts. In Study 2, novice GIS students showed superior baseline navigational competence compared to non-STEM students, as well as better spatial working memory and small-scale mental rotation skills, indicating self-selection. In addition, GIS students’ spatial skills improved more over the course of a semester than those of non-STEM students.

Conclusions

Our findings highlight the importance of large-scale spatial thinking for enrollment and success in the GEO fields but likely also across the broader range of thinking involving spatial distributions. We discuss the potential of GIS tools to develop spatial skills at an early age.