Enacting Space in Virtual Reality: A Comparison Between Money's Road Map Test and Its Virtual Version

In the field of spatial cognition research the mutual relationship between perception and action that brings out spatial orientation was lately investigated. Besides, the sameness between creating a cognitive map from the exploration of a not simulated environment, from the use of an allocentric (survey-like) sketched map, and from the interaction with egocentric (route-like) 3D virtual environments, is generally contrived. To understand if different embodied affordances could provide different knowledge organization during wayfinding through the use of distinct spatial simulations, the same group of 61 healthy subjects experienced both the classical version of the Money's Road Map test (M-RMT) and a virtual reality version of the Road Map test (VR-RMT). The M-RMT requires a allocentric to egocentric right/left reasoning to explore a stylized city provided in a survey perspective. The VR-RMT is a 3D version of the same environment through which participants can actively navigate by choosing egocentric-based right/left directions in a route perspective. The results showed that the different embodiments afforded by the two environments and the increasing complexity in turn types provides different spatial outcomes. Results were discussed according to the sensorimotor coupling theory provided from the enactive cognition approach and significances for spatial cognition research were provided.

Hippocampal neurogenesis: Learning to remember

Alzheimer's disease, the most prevalent form of dementia in the elderly, is characterized by progressive memory loss and cognitive dysfunction. It has become increasingly clear that while neuronal cell loss in the entorhinal cortex and hippocampus occurs in Alzheimer's disease, it is preceded by a long period of deficits in the connectivity of the hippocampal formation that contributes to the vulnerability of these circuits. Hippocampal neurogenesis plays a role in the maintenance and function of the dentate gyrus and hippocampal circuitry. This review will examine the evidence suggesting that hippocampal neurogenesis plays a role in cognitive function that is affected in Alzheimer's disease, will discuss the cognitive assessments used for the detection of Alzheimer's disease in humans and rodent models of familial Alzheimer's disease, and their value for unraveling the mechanism underlying the development of cognitive impairments and dementia.

Sensitivity to object impossibility in the human visual cortex: evidence from functional connectivity

Processing spatial configuration is a fundamental requirement for object recognition. Using fMRI, the neural basis underlying this ability was examined while human participants viewed possible and visually similar, but spatially impossible, objects presented for either long or short exposure duration. Response profiles in object-selective cortical regions exhibited sensitivity to object possibility, but only for the long exposure duration. Contrary, functional connectivity, indexed by the pairwise correlations between activation profiles across ROIs, revealed sensitivity to possibility, evident in enhanced correlations for impossible compared with possible objects. Such sensitivity was found even following a brief exposure duration, which allowed only minimal awareness of possibility. Importantly, this sensitivity was correlated with participants' general spatial ability as assessed by an independent neuropsychological test. These results suggest that the visual system is highly susceptible to objects' 3-D structural information even with minimal perceptual awareness. Such sensitivity is captured at the level of functional connectivity between object-selective regions, rather than the absolute level of within-region activity, implicating the role of interregional synchronization in the representation of objects' 3-D structure.

The impact of map orientation and generalisation on congestion decisions: a comparison of schematic-egocentric and topographic-allocentric maps

Map information for drivers is usually presented in an allocentric-topographic form (as with printed maps) or in an egocentric-schematic form (as with road signs). The advent of new variable message boards on UK motorways raises the possibility of presenting road maps to reflect congestion ahead. Should these maps be allocentric-topographic or egocentric-schematic? This was assessed in an eye tracking study, with participants viewing maps of a motorway network in order to identify whether any congestion was relevant to their intended route. The schematic-egocentric maps were responded to most accurately with shorter fixation durations suggesting easier processing. In particular, the driver's entrance and intended exit from the map were attended to more in the allocentric maps. Individual differences in mental rotation ability also seem to contribute to poor performance on allocentric maps. The results favour schematic-egocentric maps for roadside congestion information, but also provide theoretical insights into map-rotation and individual differences. Statement of Relevance: This study informs designers and policy makers about optimum representations of traffic congestion on roadside variable message signs and, furthermore, demonstrates that individual differences contribute to problems with processing certain sign types. Schematic-egocentric representations of a motorway network produced the best results, as noted in behavioural and eye movement measures.

TMS over the left angular gyrus impairs the ability to discriminate left from right

The underlying cognitive and neural mechanisms of the ability to discriminate left from right are hardly explored. Clinical studies from patients with impairments of left-right discrimination (LRD) and neuroimaging data suggest that the left angular gyrus is particularly involved in LRD. Moreover, it is argued that the often reported sex difference in LRD, with women being more susceptible to left-right errors than men, is the result of a stronger lateralization in men than women. Offline repetitive transcranial magnetic stimulation (rTMS) was used to test whether the left angular gyrus is involved in LRD and whether men have a stronger lateralization in LRD than women. Twenty-four participants (12 men, 12 women) completed a behavioral LRD task in three different conditions: after rTMS of the left and right angular gyrus and after 'sham' rTMS (control). The results revealed that after rTMS of the left angular gyrus, LRD accuracy rates were significantly reduced compared to the control condition. After rTMS of the right angular gyrus no difference to the control condition was observed. In addition, there was no overall sex difference in the LRD task and men and women were similarly affected by stimulation over the left and right angular gyrus, suggesting that the functional cerebral organization of LRD does not differ in men and women with similar LRD skills. Taken together, the findings suggest that the left angular gyrus is critically involved in LRD. It is argued that the left angular gyrus integrates spatial information with the meaning of the words 'left' and 'right', thereby assigning the labels 'left' and 'right' to a certain state or direction, etc.

Impact of vision on the development of topographical orientation abilities

The current experiment examined the importance of visual input on the construction of inner spatial representations. Early and late-onset blind and paired control participants performed a tactile spatial orientation task. No significant group differences were observed, indicating that the blind can represent space. More errors, however, were committed by the early blind than by the late blind and sighted individuals in portions of the task that involved mental rotation skills, suggesting a potential facilitating role for vision in the proper development of spatial constructs.

Performances of patients with a dementia of the Alzheimer type in the Standardized Road-Map test of Direction Sense

The Standardised Road-Map test of Direction Sense of money (A Standardised Road-Map Test of Direction Sense, Baltimore: Johns Hopkins University Press, 1976) was applied to a group of 14 patients diagnosed with dementia of the Alzheimer type (DAT) and to a group of 14 healthy controls matched in terms of age and education. Subjects were tested with two forms of the Money test. In the first form, the standard procedure was used. It requires patients to perform mental rotations and right or left discrimination. In the second form, the examiner turned the test sheet at each intersection to align the route with the subject. In contrast to the first condition, no mental rotation was necessary to distinguish right from left turns. This procedure has been introduced to investigate the impact of the graphic material in the map display on performance. The subjects were also given a right-left discrimination test. The results show a significant difference between DAT patients and the control group in the original form of the Money test. DAT patients also showed a deficit compared to the control subjects in the modified form of the test. The right-left discrimination test revealed no dysfunction in either group tested on problems referring to their own body parts. The designation of the body parts of somebody facing them was deficient with DAT patients. The capacity of right-left discrimination, at least with respect to parts of their own body, does not play a central role in the poor test performance of the Money test. We conclude that the Money test has a clinical value, but not specifically in the evaluation of right-left discrimination. This test should rather be viewed in terms of mental rotations and limited attention resources in DAT patients.

Block design as a measure of everyday spatial ability: a study of ecological validity

This study investigated the effectiveness of the WAIS-R Block Design subtest to predict everyday spatial ability for 65 university undergraduates (15 men, 50 women) who were administered Block Design, the Standardized Road Map Test of Direction Sense, and the Everyday Spatial Activities Test. In addition, the verbally loaded National Adult Reading Test was administered to assess whether the more visuospatial Block Design subtest was a better predictor of spatial ability. Moderate support was found. When age and sex were accounted for, Block Design accounted for 36% of the variance in performance (r = -.62) on the Road Map Test and 19% of the variance on the performance of the Everyday Spatial Activities Test (r = .42). In contrast, the scores on the National Adult Reading Test did not predict performance on the Road Map Test or Everyday Spatial Abilities Test. This suggests that, with appropriate caution, Block Design could be used as a measure of everyday spatial abilities.

Lateralization of cerebral blood flow velocity changes during cognitive tasks. A simultaneous bilateral transcranial Doppler study

BACKGROUND AND PURPOSE

Transcranial Doppler ultrasonography (TCD) permits the assessment of cognitively induced cerebral blood flow velocity (BFV) changes. We sought to investigate the lateralization of BFV acceleration induced by a variety of cognitive tasks and to determine the influence of age, gender, IQ, and quality of the performance on the relative BFV changes.

METHODS

Simultaneous bilateral TCD monitoring of BFV in the middle cerebral arteries (MCAs) was performed in 90 normal right-handed volunteers during 13 verbal and visuospatial tasks and their preceding rest periods.

RESULTS

All tasks induced a significant bilateral BFV increase in the MCAs compared with the preceding rest periods. Five verbal tasks showed a significant left-hemispheric BFV acceleration. Linguistic tasks that required active or creative processing of the verbal stimuli, such as sentence construction or word fluency, elicited the most asymmetric response. Five visuospatial tasks revealed a significant right-hemispheric BFV shift. Paradigms that combined visuospatial attention and visuomotor manipulation showed the most lateralized acceleration. Older volunteers (aged >50 years) showed higher relative BFV changes, but lateralization was not influenced by age. Gender, IQ, and performance quality did not reveal significant effects on BFV change.

CONCLUSIONS

Bilateral TCD is a noninvasive technique that has the potential to connect the particular change in flow pattern of the MCA distribution with selective cognitive activity and thus offers specific functional information of scientific and clinical value.