Navigating Cognitive Maps: Statistical Analysis of 3D Path Data in Minecraft.

Sleep facilitates hippocampal-dependent memories, supporting the acquisition and maintenance of internal representation of spatial relations within an environment. In humans, however, findings have been mixed regarding sleep's contribution to spatial memory and navigation, which may be due to task designs or outcome measurements. We developed the Minecraft Memory and Navigation (MMN) task for the purpose of disentangling how spatial memory accuracy and navigation change over time, and to study sleep's independent contributions to each. In the MMN task, participants learned the locations of objects through free exploration of an open field computerized environment. At test, they were teleported to random positions around the environment and required to navigate to the remembered location of each object. In study 1, we developed and validated four unique MMN environments with the goal of equating baseline learning and immediate test performance. A total of 86 participants were administered the training phases and immediate test. Participants' baseline performance was equivalent across all four environments, supporting the use of the MMN task. In study 2, 29 participants were trained, tested immediately, and again 12 h later after a period of sleep or wake. We found that the metric accuracy of object locations, i.e., spatial memory, was maintained over a night of sleep, while after wake, metric accuracy declined. In contrast, spatial navigation improved over both sleep and wake delays. Our findings support the role of sleep in retaining the precise spatial relationships within a cognitive map; however, they do not support a specific role of sleep in navigation.

There is considerable research on the neurobiological mechanisms within the hippocampal system that support spatial navigation. In this article I review the literature on navigational strategies in humans and animals, observations on hippocampal function in navigation, and studies of hippocampal neural activity in animals and humans performing different navigational tasks and tests of memory. Whereas the hippocampus is essential to spatial navigation via a cognitive map, its role derives from the relational organization and flexibility of cognitive maps and not from a selective role in the spatial domain. Correspondingly, hippocampal networks map multiple navigational strategies, as well as other spatial and nonspatial memories and knowledge domains that share an emphasis on relational organization. These observations suggest that the hippocampal system is not dedicated to spatial cognition and navigation, but organizes experiences in memory, for which spatial mapping and navigation are both a metaphor for and a prominent application of relational memory organization.

In the mammalian brain, histaminergic neurotransmission is mediated by the postsynaptic histamine H1 and H2 receptors and the presynaptic H3 autoreceptor, which also acts as a heteroreceptor. The H1 receptor has been implicated in spatial learning and memory formation. However, pharmacological and lesion studies have revealed conflicting results. To examine the involvement of histamine H1 receptor in spatial reference and working memory formation, H1 receptor knockout mice (KO) were tested in the eight-arm radial maze. Previously, we found that the H1 receptor-KO mice showed reduced emotionality when confronted with spatial novelty. As it is known that emotions can have an impact on spatial learning and memory performance, we also evaluated H1 receptor-KO mice in terms of emotional behaviour in the light-dark box. Mice lacking the H1 receptor and wild-type mice (WT) were tested for spatial reference and working memory in an eight-arm radial maze with three arms baited and one trial per day. Emotional behaviour was measured using the light-dark test. The H1 receptor-KO mice showed impaired spatial reference and working memory in the radial maze task. No significant differences between H1 receptor-KO and WT mice were observed in the light-dark test. The spatial memory deficits of the H1 receptor-KO mice might be due to the reported changes in cholinergic neurochemical parameters in the frontal cortex and the CA1 subregion of the hippocampus, to impaired synaptic plasticity in the hippocampus, and/or to a dysfunctional brain reward/reinforcement system.

Stroke is the third most common cause of death and the primary cause of morbidity in the United Kingdom. It can be associated with deterioration in both sensorimotor and cognitive skills. Proximal occlusion of the middle cerebral artery (MCAO) in rodents is a widely used model of experimental cerebral ischaemia, which has been used to investigate the effect of stroke on cognition in spatial learning, such as the watermaze. However, findings to-date have been varied, depending on when testing was started after MCAO and the duration of training and testing, raising doubts about the utility of MCAO in rodents to study memory deficits. The present study was designed to discriminate between sensorimotor and spatial memory to establish whether MCAO has a significant influence on both the acquisition and retention of spatial memory. Female Lister Hooded rats (n=10) underwent MCAO. The artery was electrocoagulated from the origin of the lenticulostriate arteries to the inferior cerebral vein and then transected to ensure complete occlusion. Sham animals (n=9) underwent the same procedure except the artery was not occluded or transected and a group of naive, unoperated animals (n=8) was included. Training in the watermaze commenced 10 days after MCAO with 3 days of training to a visible escape platform of varying positions from different start positions. The animals were then trained to find a hidden escape platform at a fixed location (spatial reference memory). The start position was varied and the first trial every day was a probe trial where no platform was present for the first 60 seconds. For acquisition, animals were trained until they spent at least 50% of the probe trial in the quadrant where the platform was normally placed (target quadrant) for 3 consecutive days. The retention of memory was tested 1, 7 and 28 days after this criterion was reached. MCAO induced a consistent infarct involving both cortex and caudate which by 28 days was represented by ipsilateral tissue loss of 32.1 2.8 % of the contralateral hemisphere (mean S.E.M). The watermaze results revealed no deficit in acquisition or retention of memory in MCAO animals compared to sham and naive animals. There was no difference in the average number of days to reach acquisition criterion (Graph 1), and no difference in the proportion of time spent in the target quadrant during the retention tests (Graph 2). Data are presented as mean S.E.M. In conclusion, this study, designed to differentiate between spatial memory and sensorimotor deficits, revealed no evidence for deficits in memory acquisition or retention following MCAO. (See Figure 1).

Which facets of human spatial navigation do sex and menstrual cycle influence? To answer this question, a cross-sectional online study of reproductive age women and men was conducted in which participants were asked to demonstrate and self-report their spatial navigation skills and strategies. Participants self-reported their sex and current menstrual phase [early follicular (EF), late follicular/periovulatory (PO), and mid/late luteal (ML)], and completed a series of questionnaires and tasks measuring self-reported navigation strategy use, topographical memory, cognitive map formation, face recognition, and path integration. We found that sex influenced self-reported use of cognitive map- and scene-based strategies, face recognition, and path integration. Menstrual phase moderated the influence of sex: compared to men, women had better face recognition and worse path integration, but only during the PO phase; PO women were also better at path integration in the presence of a landmark compared to EF + ML women and men. These findings provide evidence that human spatial navigation varies with the menstrual cycle and suggest that sensitivity of the entorhinal cortex and longitudinal axis of the hippocampus to differential hormonal effects may account for this variation.

Aims: Pre- and/or early postnatal ethanol exposure (prenatal alcohol exposure [PAE]) impairs synaptic plasticity as well as memory formation, but the mechanisms underlying these effects remain unclear. Both long-term potentiation (LTP) and spatial memory formation in the hippocampus involve the nicotinamide adenine dinucleotide phosphate oxidase type 2 (NOX2) enzyme. Previous studies have reported that N-methyl-d-aspartate receptor (NMDAR) activation increases NOX2-mediated superoxide generation, resulting in inhibition of NMDAR function, but whether NOX2 impacts NMDAR function in PAE animals leading to impaired LTP and memory formation remains unknown. We aim to evaluate whether the NOX2-NMDAR complex is involved in the long-lasting deleterious effects of PAE on hippocampal LTP and memory formation. Results: Here we provide novel evidence that PAE animals display impaired NMDAR-dependent LTP in the cornus ammonis field 1 (CA1) and NMDAR-mediated LTP in the dentate gyrus (DG). Moreover, PAE rats displayed increased NMDAR-mediated transmission in both hippocampal areas. Interestingly, NOX2 pharmacological inhibition restored NMDAR-mediated transmission and LTP in the CA1, but not in the DG. PAE also induced overexpression of NOX2 and CaMKII isoforms, but did not modify the content or the redox state of the N-methyl-d-aspartate receptor subunit-1 (NR1) subunit of NMDAR in both areas of the hippocampus. In addition, adolescent PAE rats orally fed the antioxidant and free radical scavenger apocynin exhibited significantly improved spatial memory acquisition. Innovation and Conclusion: By showing in PAE animals NOX2 overexpression and increased NMDAR-mediated transmission, which might lead to impaired synaptic plasticity and memory formation in a region-specific manner, we provide an important advance to our current understanding of the cellular mechanisms underlying PAE-dependent defective hippocampal function.

Investigations into how individual neurons encode behavioral variables of interest have revealed specific representations in single neurons, such as place and object cells, as well as a wide range of cells with conjunctive encodings or mixed selectivity. However, as most experiments examine neural activity within individual tasks, it is currently unclear if and how neural representations change across different task contexts. Within this discussion, the medial temporal lobe is particularly salient, as it is known to be important for multiple behaviors including spatial navigation and memory, however the relationship between these functions is currently unclear. Here, to investigate how representations in single neurons vary across different task contexts in the medial temporal lobe, we collected and analyzed single-neuron activity from human participants as they completed a paired-task session consisting of a passive-viewing visual working memory and a spatial navigation and memory task. Five patients contributed 22 paired-task sessions, which were spike sorted together to allow for the same putative single neurons to be compared between the different tasks. Within each task, we replicated concept-related activations in the working memory task, as well as target-location and serial-position responsive cells in the navigation task. When comparing neuronal activity between tasks, we first established that a significant number of neurons maintained the same kind of representation, responding to stimuli presentations across tasks. Further, we found cells that changed the nature of their representation across tasks, including a significant number of cells that were stimulus responsive in the working memory task that responded to serial position in the spatial task. Overall, our results support a flexible encoding of multiple, distinct aspects of different tasks by single neurons in the human medial temporal lobe, whereby some individual neurons change the nature of their feature coding between task contexts.

Mapping the response: A survey of municipal firefighter navigation training and practices in the United States

This study investigated the relationship among spatial scanning ability, perceptual speed, and navigation performance in older and younger drivers. Fifty-six drivers performed a navigation task in a part-task driving simulator using: 1) text directions, 2) a standard paper map, 3) an enlarged paper map, and 4) a turn-by-turn display. Measures included navigation error rate and decision time, and spatial scanning and perceptual speed scores. Younger drivers performed better than the older drivers in error rate and decision time, and the turn-by-turn display improved performance compared to either map. Spatial scanning ability was a stronger predictor of error rate, while perceptual speed was a stronger predictor of decision time. The results suggest that navigation aids requiring minimal spatial and perceptual processing can improve navigation performance.

Smartphones are useful personal assistants and omnipresent communication devices. However, collaboration is not among their strengths. With the advent of embedded projectors this might change. We conducted a study with 56 participants to find out if map navigation and spatial memory performance among users and observers can be improved by using a projector phone with a peephole interface instead of a smartphone with its touchscreen interface. Our results show that users performed map navigation equally well on both interfaces. Spatial memory performance, however, was 41% better for projector phone users. Moreover, observers of the map navigation on the projector phone were 25% more accurate when asked to recall locations of points of interest after they watched a user performing map navigation.

Influence of visual stimuli on spatial navigation and memory of MCI, Alzheimer's disease patients and healthy control subjects

Age differences in pedestrian navigational skills and performance: A systemic review and meta-analysis.

Consistency of cognitive performance in spatial navigation and its link to activity and boldness in laboratory rats.

Among the different capabilities of animals, the formation of spatial memories is crucial for their life. Living beings able to move, constantly need to orient themselves in the environment to reach a target that might be not always visible. This chapter investigates the process of spatial memory formation as an essential ingredient for orientation in open and unstructured environments. Neural centres devoted to spatial memory and path integration were deeply investigated both in rats and different insect species like ants, bees and fruit flies. In this chapter a neural-inspired model for the formation of a spatial working memory is discussed considering some key elements of the insect neural centres involved, in particular the ellipsoid body of the central complex.

Effects of brain lesions on human spatial navigation