Males and females use different distal cues in a virtual environment navigation task

The evolution of sex differences in spatial ability

It is widely believed that male mammals have better spatial ability than females. A large number of evolutionary hypotheses have been proposed to explain these differences, but few species have been tested. The authors critically review the proposed evolutionary explanations for sex differences in spatial cognition and conclude that most of the hypotheses are either logically flawed or, as yet, have no substantial support. Few of the data exclusively support or exclude any current hypotheses. The hypothesis with the strongest support proposes that range size was the selection pressure that acted to increase spatial ability. The authors suggest ways in which these hypotheses could be tested by presenting explicit predictions and suggesting suitable test species or conditions.

Navigation expertise and the human hippocampus: a structural brain imaging analysis

Grey matter volume in the posterior hippocampus of London taxi drivers is greater than in age-matched controls, and the size of this increase correlates positively with time spent taxi driving (E.A. Maguire et al., 2000. Proc Natl Acad Sci USA 97: 4398-4403). This change suggests that increased posterior hippocampal grey matter volume is acquired in response to increased taxi driving experience, perhaps reflecting their detailed representation of the city. However, an alternate hypothesis is that the difference in hippocampal volume is instead associated with innate navigational expertise, leading to an increased likelihood of becoming a taxi driver. To investigate this possibility, we used structural brain imaging and voxel-based morphometry (VBM) to examine a group of subjects who were not taxi drivers. Despite this group showing a wide range of navigational expertise, there was no association between expertise and posterior hippocampal grey matter volume (or, indeed, grey matter volume throughout the brain). This failure to find an association between hippocampal volume and navigational expertise thus suggests that structural differences in the human hippocampus reflect the detail and/or duration of use of the spatial representation acquired, and not innate navigational expertise per se.

Unpacking the cognitive map: the parallel map theory of hippocampal function

In the parallel map theory, the hippocampus encodes space with 2 mapping systems. The bearing map is constructed primarily in the dentate gyrus from directional cues such as stimulus gradients. The sketch map is constructed within the hippocampus proper from positional cues. The integrated map emerges when data from the bearing and sketch maps are combined. Because the component maps work in parallel, the impairment of one can reveal residual learning by the other. Such parallel function may explain paradoxes of spatial learning, such as learning after partial hippocampal lesions, taxonomic and sex differences in spatial learning, and the function of hippocampal neurogenesis. By integrating evidence from physiology to phylogeny, the parallel map theory offers a unified explanation for hippocampal function.

The role of ovarian hormones in preserving cognition in aging

Hormone replacement therapy is now the standard of care for amelioration of the symptoms of menopause and prevention of osteoporosis. More recently, it has been appreciated that hormone replacement may also have beneficial effects on the brain. This review will contrast the biologic data showing that estrogen has significant neuroprotectant effects on the brain, with data from cross-sectional and epidemiologic studies of women showing that hormone replacement may have beneficial effects for cognition in aging. Together, studies suggest that the temporal pattern of hormone replacement may be critical for maintaining cognitive health in aging.

Effects of age on virtual environment place navigation and allocentric cognitive mapping

This study assessed age differences in navigational behavior in a virtual Morris water maze (vMWM) and examined the ability of older adults to develop cognitive maps after vMWM experience. Compared with younger participants, older volunteers traversed a longer linear distance to locate the hidden platform. On the probe trial, younger volunteers spent a greater proportion of their total distance traveled in proximity to the platform and had more platform intersections. Analysis of map reproductions demonstrated that older participants used proximal objects to locate the goal but did not use room-geometry cues to aid navigation. These findings demonstrate age-related deficits on a laboratory measure of place learning and suggest that deficiencies in allocentric mapping may contribute to these deficits.

Virtual reality and neuropsychology: upgrading the current tools

BACKGROUND

Virtual reality (VR) is an evolving technology that has been applied in various aspects of medicine, including the treatment of phobia disorders, pain distraction interventions, surgical training, and medical education. These applications have served to demonstrate the various assets offered through the use of VR.

OBJECTIVE

To provide a background and rationale for the application of VR to neuropsychological assessment.

METHODS

A brief introduction to VR technology and a review of current ongoing neuropsychological research that integrates the use of this technology.

CONCLUSIONS

VR offers numerous assets that may enhance current neuropsychological assessment protocols and address many of the limitations faced by our traditional methods.

Assessing the behavioral and cognitive effects of seizures on the developing brain

The degree to which seizures lead to 'brain damage' is not fully known, but this question has important clinical implications. Seizure-induced brain damage can be defined in several ways: structural, physiological, and behavioral. The behavioral and cognitive effects of seizures are difficult to ascertain in patients, because it is hard to differentiate the effects of the seizures from the underlying brain pathology, anticonvulsant treatment, and developmental variables. In animal models, the ability to control seizure variables allows detailed investigation of factors that cannot be easily distinguished in clinical studies. In models of experimental epilepsy, both brief and prolonged seizures lead to brain damage. While the consequences of seizures are much more extensive in the adult brain, long-term alterations are also seen in the developing brain. This chapter focuses on the effects of seizures during development on subsequent behavior and cognition in experimental epilepsy models. The investigator must choose carefully among the various tests of behavior, learning, memory, and cognition, since the existence or extent of deficits may depend upon which test is selected and how the data are analyzed. The experimental evidence suggests that seizures early in life are associated with subtle deficits in behavior and cognition, even in the absence of overt structural neuronal damage. These deficits are dependent upon the age at which seizures occur (less severe deficits at younger ages), seizure frequency and seizure severity, but are largely independent of seizure etiology, occurring after several types of chemoconvulsants and electrical stimulation. Seizure-induced behavioral and cognitive deficits, which may not become obvious until long after the onset of the epilepsy, might be equally or more detrimental to a child's overall function than the seizures themselves.

The human hippocampus and spatial and episodic memory

Finding one's way around an environment and remembering the events that occur within it are crucial cognitive abilities that have been linked to the hippocampus and medial temporal lobes. Our review of neuropsychological, behavioral, and neuroimaging studies of human hippocampal involvement in spatial memory concentrates on three important concepts in this field: spatial frameworks, dimensionality, and orientation and self-motion. We also compare variation in hippocampal structure and function across and within species. We discuss how its spatial role relates to its accepted role in episodic memory. Five related studies use virtual reality to examine these two types of memory in ecologically valid situations. While processing of spatial scenes involves the parahippocampus, the right hippocampus appears particularly involved in memory for locations within an environment, with the left hippocampus more involved in context-dependent episodic or autobiographical memory.

Are sex differences in navigation caused by sexually dimorphic strategies or by differences in the ability to use the strategies?

When navigating, women typically focus on landmarks within the environment, whereas men tend to focus on the Euclidean properties of the environment. However, it is unclear whether these observed differences in navigational skill result from disparate strategies or disparate ability. To remove this confound, the present study required participants to follow either landmark- or Euclidean-based instructions during a navigation task (either in the real-world or on paper). Men performed best when using Euclidean information, whereas women performed best when using landmark information, suggesting a dimorphic capacity to use these 2 types of spatial information. Further, a significant correlation was observed between the mental rotation task and the ability to use Euclidean information, but not the ability to use landmark information.

Large visuospatial sex difference in line judgment: possible role of attentional factors

This article describes a large sex difference on a new, group-administered visuospatial task, the Judgment of Line Angle and Position (JLAP) test, and investigates the role of attentional factors in the difference. On the JLAP, adapted from a neuropsychological task (Benton et al., 1983), participants evaluate spatial attributes of lines. Study 1: College males (N = 48) outperformed females (N = 80), resulting in a large effect for sex (d = 0.85). Errors were more common on oblique (vs horizontal or vertical) lines, especially for females. Study 2: Task attributes were manipulated (N = 33 males and 36 females) to study the role of attentional factors. Findings suggest that males are more likely than females to normally attend to and be aided by geometrical reference cues.

The role of self-to-object updating in orientation-free performance on spatial-memory tasks

A single view of a room-sized path produces an orientation-specific memory representation, yet when memory is tested at a location on the path, orientation-free performance is observed. Either a virtual-views or an updating hypothesis can account for orientation-free performance by attributing it, respectively, to an orientation-free long-term-memory representation or to a working-memory representation of the body's updated location relative to the path. Experiments 1 and 2 test these hypotheses by manipulating the test-site location and the complexity of the trajectory from the study site to the test site. Experiment 3 tests orientation to the test space as a function of trajectory complexity. Results support a virtual-views explanation for the orientation-free performance of males and an updating explanation for females.

Cognitive subprocesses of mental rotation: why is a good rotator better than a poor one?

The Vanderberg-Kuse Mental Rotation Test is a standard test of mental rotation ability. Recent experiments have demonstrated that mental rotation is a complex cognitive process wherein different subprocesses (focused attention, visual scanning, perceptual decision, visual memory) play important roles in performance. We classified the population as good and poor rotators by performance of mental rotation (ns = 47: 22 men and 25 women, respectively; mean age: 20.7 yr.). To examine differences cognitive subprocesses of mental rotation of these two groups were compared. There were significant differences between poor and good rotators in performance on Raven's test and the Pieron Focused Attention test scores. The good rotators scored better because their perceptual decision-analytical intelligence (Raven) and focused attention scores were higher.

The effect of response contingencies on scale model task performance by chimpanzees (Pan troglodytes)

The effects of modified procedures on chimpanzees' (Pan troglodytes) performance in a scale model comprehension task were examined. Seven chimpanzees that previously participated in a task in which they searched an enclosure for a hidden item after watching an experimenter hide a miniature item in the analogous location in a scale model were retested under procedures incorporating response costs. In Experiment 1, chimpanzees were trained under procedures that rewarded only item retrievals occurring on the 1st search attempt. During test trials, 6 chimpanzees performed above chance, including 4 that were previously unsuccessful under the original procedures (V. A. Kuhlmeier, S. T. Boysen, & K. L. Mukobi, 1999). Experiment 2 compared performance under the new and original procedures. Results indicated that for some chimpanzees, performance depended on procedures that decreased the use of competing search strategies and encouraged strategies based on information from the scale model.

Age differences in spatial memory in a virtual environment navigation task

The use of virtual environment (VE) technology to assess spatial navigation in humans has become increasingly common and provides an opportunity to quantify age-related deficits in human spatial navigation and promote a comparative approach to the neuroscience of cognitive aging. The purpose of the present study was to assess age differences in navigational behavior in a VE and to examine the relationship between this navigational measure and other more traditional measures of cognitive aging. Following pre-training, participants were confronted with a VE spatial learning task and completed a battery of cognitive tests. The VE consisted of a richly textured series of interconnected hallways, some leading to dead ends and others leading to a designated goal location in the environment. Compared to younger participants, older volunteers took longer to solve each trial, traversed a longer distance, and made significantly more spatial memory errors. After 5 learning trials, 86% of young and 24% of elderly volunteers were able to locate the goal without error. Performance on the VE navigation task was positively correlated with measures of mental rotation and verbal and visual memory.

Sex differences in the dynamics of cue utilization and exploratory behavior

The purpose of the present study was to investigate the effects of sex and estrous cycle on exploratory behavior, as well as the degree to which reliance on environmental cues changes with training. Fischer 344 rats were placed three times in an open field box that contained three objects (two identical bottles and a cylinder). During the initial exposure to the environment all females showed higher activity levels and explored a larger region of the environment compared to males. However, upon subsequent exposure to the same environment, these sex differences disappeared. During the third and final session, the locations of the bottle and the cylinder were switched. The estrous females and to a lesser degree male rats, responded to the relocation of objects with a renewal of exploration and activity; proestrous females did not show this response. The rats were then trained on a four-arm radial maze reference memory task. The correct arm could be located by its relation to extra-room cues, a large distal white panel, or to local inserts on the maze. Once the animals consistently chose the goal arm, a probe session was conducted to determine which cues the animals were using to solve the task. During the probe trial both the white panel and the local inserts were rotated 90 degrees clockwise and counterclockwise respectively and the animals' choice of arm recorded. During the first probe, females tended to rely on all three types of cues in solving the task. With additional training there was a shift towards predominantly using the distal visual information. In contrast, male rats did not show this shift; by the first probe session the males were predominantly using the distal visual information to solve the task. The findings indicate: (1) sex differences in the initial use of environmental cues; (2) the usage of environmental information is dynamic and changes with additional exposures to the environment. The results are related to previous findings on sex differences and estrous cycle effects, with an emphasis on the implications for hippocampal processing.

Place learning in virtual space. III: Investigation of spatial navigation training procedures and their application to fMRI and clinical neuropsychology

This paper describes the utilization of a desktop virtual environment task, the Computer-Generated (C-G) Arena, in the study of human spatial navigation. First, four experiments examined the efficacy of various training procedures in the C-G Arena. In Experiment 1, participants efficiently located a hidden target after only observing the virtual environment from a fixed position (placement learning). In Experiment 2, participants efficiently located a hidden target after only observing an experimenter search the virtual environment (observational learning). In Experiment 3, participants failed to display a latent learning effect in the virtual environment. In Experiment 4, all training procedures effectively taught participants the layout of the virtual environment, but the observational learning procedure most effectively taught participants the location of a hidden target within the environment. Finally, two experiments demonstrated the application of C-G Arena procedures to neuroimaging (Experiment 5) and neuropsychological (Experiment 6) investigations of human spatial navigation.

Brain activation during human navigation: gender-different neural networks as substrate of performance

Visuospatial navigation in animals and human subjects is generally studied using maze exploration. We used functional MRI to observe brain activation in male and female subjects as they searched for the way out of a complex, three-dimensional, virtual-reality maze. Navigation activated the medial occipital gyri, lateral and medial parietal regions, posterior cingulate and parahippocampal gyri as well as the right hippocampus proper. Gender-specific group analysis revealed distinct activation of the left hippocampus in males, whereas females consistently recruited right parietal and right prefrontal cortex. Thus we demonstrate a neural substrate of well established human gender differences in spatial-cognition performance.

Reference memory, anxiety and estrous cyclicity in C57BL/6NIA mice are affected by age and sex

Age-related changes in learning and memory are common in rodents. However, direct comparisons of the effects of aging on learning and memory in both males and females are lacking. The present study examined whether memory deteriorates with increasing age in C57BL/6NIA mice, and whether age-related changes in learning and memory are similar in both sexes. Male and female mice (five, 17 and 25 months of age) were tested in a battery of behavioral tasks including the Morris water maze (spatial and non-spatial reference memory), simple odor discrimination (olfactory reference memory), plus maze (anxiety/exploration), locomotor activity, and basic reflexes. Five-month-old mice learned the water maze and odor discrimination tasks rapidly. Relative to five-month-old mice, 25-month-old mice exhibited impaired spatial and olfactory reference memory, but intact non-spatial reference memory. The spatial reference memory of 17-month-old mice was also impaired, but less so than 25-month mice. Seventeen-month-old mice exhibited intact non-spatial (visual and olfactory) reference memory. Five and 25-month-old mice had similar levels of plus maze exploration and locomotor activity, whereas 17-month-old mice were more active than both groups and were slightly less exploratory than five-month-old mice. Although sex differences were not observed in the five- and 25-month groups, 17-month-old females exhibited more impaired spatial reference memory and increased anxiety relative to 17-month-old males. Estrous cycling in females deteriorated significantly with increased age; all 25-month-old females had ceased cycling and 80% of 17-month-old females displayed either irregular or absent estrous cycling. This study is the first to directly compare age-related mnemonic decline in male and female mice. The results suggest that: (i) aged mice exhibit significant deficits in spatial and olfactory reference memory relative to young mice, whereas middle-aged mice exhibit only a moderate spatial memory deficit and; (ii) spatial reference memory decline begins at an earlier age in females than in males, a finding that may be related to the cessation of estrous cycling.

Sex differences on the hand mental rotation task for 9-yr.-old children and young adults

The Hand Mental Rotation task is assumed to activate an egocentric spatial reference frame to realize mental rotation. This study presents significant sex differences in hand mental rotation performances between men and women (n = 23 and 25, respectively; age: 20.7 yr.). Differences in hand mental rotation in school girls and boys (ns = 48 and 41, respectively; age: 9 yr.) were not significant. Our results suggest that the change in sex differences in egocentric mental rotation may occur with developmental change. This requires further testing with a larger sample so testing can occur at several ages between 9 and 20.7 years.

Immersive virtual environment technology as a basic research tool in psychology

Immersive virtual environment (IVE) technology has great promise as a tool for basic experimental research in psychology. IVE technology gives participants the experience of being surrounded by the computer-synthesized environment. We begin with a discussion of the various devices needed to implement immersive virtual environments, including object manipulation and social interaction. We review the benefits and drawbacks associated with virtual environment technology, in comparison with more conventional ways of doing basic experimental research. We then consider a variety of examples of research using IVE technology in the areas of perception, spatial cognition, and social interaction.

Human spatial navigation: cognitive maps, sexual dimorphism, and neural substrates

Recent research on navigation has been particularly notable for the increased understanding of the factors affecting human navigation and the neural networks supporting it. The use of virtual reality environments has made it possible to explore the effect of environment layout and content on way-finding performance, and it has shown that these effects may interact with the sex and age of subjects. Functional brain imaging, combined with the use of virtual environments, has revealed strong parallels between humans and other animals in the neural basis of navigation.