Gennaro Ruggiero

Visuospatial Memory in Healthy Elderly, AD and MCI: A Review

In the literature it is commonly reported that several spatial abilities decline with normal aging, even though such a decline is not uniform. So far, it is not yet clear which spatial components present a normal age-related decline, which ones are preserved and at what point the deficit is so severe to represent an index of mild cognitive impairment (MCI) or a symptom of potential degenerative progression as in the early-stage Alzheimers disease (AD). In particular, AD (from early onset) is characterised by impairments in constructive abilities, visuospatial intelligence, spatial short-term memory deficits, and disorders of spatial orientation (topographical disorientation). MCI indicates a condition, generally affecting older individuals, characterized by cognitive deficits including memory and/or non memory impairments and at high risk of progression to dementia. Three MCI subgroups have been distinguished and a very high risk of developing AD is associated to the amnestic MCI subtypes. Further, recent studies have suggested that the allocentric component of spatial memory might be taken as predictor of AD from MCI. Given the frequency of visuospatial deficits in early-stage AD, evaluation of visuospatial processes is a promising approach to find predictive markers of AD. Here we report a review of the literature exploring specific visuospatial components in normal aging, MCI, and AD. In this way we could shed some light on the role of these components in the progression from MCI to AD and pave the way for future studies.

Gender differences in object location memory in a real three-dimensional environment

In this preliminary study we investigate gender differences in object location memory. Our purpose is to extend the results about object location memory obtained in laboratory settings to a real 3-D environment and to further distinguish the specific components involved in this kind of memory by considering the strategies adopted to perform the task. To do this, we join the three-level model of spatial representations (landmark, route, and survey) proposed by Siegel and White (1975) with the three subcomponents of spatial memory (what, where, and what + where) identified by Postma and De Haan (1996). We adopted the object relocation task devised by Postma and De Haan (1996), adapted to a real environment. Seven common objects were placed on the floor of a cylindrical room. Sixty-four males and 64 females were asked to memorize the spatial layout. Next, the experimenter moved the objects to a different position along with seven new objects and the participants had to relocate the original objects to their initial positions. In line with Postma, Izendoorn, and De Haan (1998), we found no gender difference in object recognition, and in recalling absolute distance and categorical spatial relations; however males were better than females in recalling the distance between objects and the size of the layout. Overall, the data show a male advantage in some components of spatial cognition closely linked to the encoding of the metric structure of the spatial relationships at both route and survey level.

Gender differences in remembering and inferring spatial distances

The abilities of males and females to make spatial inferences were compared. Spatial inference is concerned with the ability to work out new spatial information from memory. In two experiments, participants had to study line drawings depicting shapes linked either by straight or meandering lines. Afterwards, they had to remember the straight-line distances or to infer the straight-line distances. Several spatial abilities were also assessed: perceptual discrimination, mental rotation, and visuo-spatial working memory span. The results showed that males outperformed females in spatial inference and mental rotation. Experiment 2 extended the study to old people. The results replicated and clarified those obtained in Experiment 1. Spatial inference and mental rotation showed age-related and gender-related differences; in addition, age reduced the visuo-spatial memory span. Overall, the findings suggest that gender differences favouring males are maximised with tasks requiring active processing and strategic control of metric information.

Age differences in mental scanning of locomotor maps

Purpose. To investigate whether the metric quality of mental spatial representations of the environment changes with aging, by means of mental scanning of locomotor space. Method. Twenty young adults (age 21.1 – 30.8) and 20 old adults (age 60.4 – 76.4) were submitted to a battery of psychometric tests to assess the effects of aging on general cognitive functions and specific visuo-spatial abilities, and to determine which cognitive factors correlated with scanning performance. The mental scanning task followed. Participants firstly had to learn a path comprising six positions by walking and observing these; secondly, they had to use mental imagery to scan from a first to a second position, according to different distances. Results. Aging reduces the validity of the metric information incorporated by mental spatial representations. Attentional and working memory resources, ability to manipulate spatial information and a general factor of abstract visuo-spatial reasoning strongly correlated with scanning performance. Finally, aging seemed to have a selective effect on cognitive functioning. Conclusions. Age differences emerge when demanding storage and processing of information are simultaneously required, as predicted by the Limited Resources view of aged cognition.

Lateralization of egocentric and allocentric spatial processing after parietal brain lesions

The purpose of this paper was to verify whether left and right parietal brain lesions may selectively impair egocentric and allocentric processing of spatial information in near/far spaces. Two Right-Brain-Damaged (RBD), 2 Left-Brain-Damaged (LBD) patients (not affected by neglect or language disturbances) and eight normal controls were submitted to the Ego-Allo Task requiring distance judgments computed according to egocentric or allocentric frames of reference in near/far spaces. Subjects also completed a general neuropsychological assessment and the following visuospatial tasks: reproduction of the Rey-Osterreith figure, line length judgement, point position identification, mental rotation, mental construction, line length memory, line length inference, Corsi block-tapping task. LBD patients presented difficulties in both egocentric and allocentric processing, whereas RBD patients dropped in egocentric but not in allocentric judgements, and in near but not far space. Further, RBD patients dropped in perceptually comparing linear distances, whereas LBD patients failed in memory for distances. The overall pattern of results suggests that the right hemisphere is specialized in processing metric information according to egocentric frames of reference. The data are interpreted according to a theoretical model that highlights the close link between egocentric processing and perceptual control of action.

Body Space in Social Interactions: A Comparison of Reaching and Comfort Distance in Immersive Virtual Reality

Background Do peripersonal space for acting on objects and interpersonal space for interacting with con-specifics share common mechanisms and reflect the social valence of stimuli? To answer this question, we investigated whether these spaces refer to a similar or different physical distance. Methodology Participants provided reachability-distance (for potential action) and comfort-distance (for social processing) judgments towards human and non-human virtual stimuli while standing still (passive) or walking toward stimuli (active). Principal Findings Comfort-distance was larger than other conditions when participants were passive, but reachability and comfort distances were similar when participants were active. Both spaces were modulated by the social valence of stimuli (reduction with virtual females vs males, expansion with cylinder vs robot) and the gender of participants. Conclusions These findings reveal that peripersonal reaching and interpersonal comfort spaces share a common motor nature and are sensitive, at different degrees, to social modulation. Therefore, social processing seems embodied and grounded in the body acting in space.

The role of vision in egocentric and allocentric spatial frames of reference

Spatial frames of reference are necessary to encode and to represent the position of objects in space. Egocentric frames define spatial information in relation to the body, while allocentric ones use external landmarks (e.g. Paillard 1991). The processing of spatial frames of reference is functional to several purposes, from acting to recognizing scenes and objects. Given the important role of vision in action and spatial memory (see Milner and Goodale 1995), the question arises of how egocentric and allocentric relations are processed in the absence of vision. It is not yet clear what is the role of vision in the spatial domain. Some data showed that blind people do not differ from controls in memory for haptically explored spatial layouts, but others revealed specific limitations (ThinusBlanc and Gaunet 1997). Few studies have directly addressed the issue of egocentric/allocentric processing. Overall, they have shown that the blind relied mainly on egocentric frames and found it difficult to deal with allocentric frames (for reviews Cattaneo et al. 2008; Thinus-Blanc and Gaunet 1997). For example, blind participants performed worse than sighted participants in spatial judgements starting from an allocentric rather than egocentric representation (Byrne and Salter 1983). Rieser et al. (1992) found that blind participants performed similarly to blindfolded sighted participants in pointing to previously learned objects from the same egocentric position, but met difficulties from a different allocentric position. Similar results were reported by Coluccia et al. (2009) in an object relocation task. Some studies are based on the idea that a small delay allows for a shift from an egocentric to an allocentric frame. Rossetti et al. (1996) reported that a delayed pointing task facilitated the use of allocentric frames of reference in blindfolded sighted but not congenital blind participants. Postma et al. (2006) found facilitation in a delayed haptic rotation task for sighted and adventitious, but not congenital participants. It should be noticed, however, that few studies showed that the blind may rely efficiently on allocentric frames of reference (Gaunet et al. 2007; Ittyerah et al. 2007). Nevertheless, it looks quite convincing that blind people, especially if congenital, should reveal limitations in processing allocentric but not egocentric information. In this research, the impact of visual experience on the capacity to use egocentric and allocentric spatial frames of reference was studied. Persons with different degrees of visual experience were compared: early (congenital) and late (adventitious) onset of blindness, short-term deprivation (blindfolded) and full vision (sighted). Participants were submitted to a spatial task that required either egocentric or allocentric processing of metric relations (see Iachini and Ruggiero 2006; Iachini et al. 2009). They had to memorize three-dimensional objects laid on the floor through haptic and locomotor exploration. After a delay, they had to provide spatial judgments of relative distance in relation to either the subject or another object. We expected a worse performance of congenital participants than all other groups in allocentric judgements, but no significant differences between groups in egocentric judgements. Finally, performance of adventitious participants should be in between that of congenital and sighted controls. G. Ruggiero (&) F. Ruotolo T. Iachini Department of Psychology, Second University of Naples, Via Vivaldi 43, 81100 Caserta, Italy e-mail: gennaro.ruggiero@unina2.it

The Lost Ability to Find the Way: Topographical Disorientation After a Left Brain Lesion

OBJECTIVE We report the case of a patient (M.S.) who, after a left brain damage in posteromedial areas, showed a deficit in determining the direction of any destination with respect to his current position or to external frames (heading disorientation). Given that spatial cognition includes a wide range of cooperating abilities, we deemed that M.S.s spatial disorientation could be ascribed to specific alterations within this multicomponent system where landmarks and spatial frames of reference contribute to organize information for different purposes. METHOD M.S. and 12 healthy elderly people (NCs) were submitted to an extensive neuropsychological assessment and to 2 ad hoc spatial tasks: (a) Object-Location Memory Task (what, where, and their binding); and (b) spatial memory task combining categorical (nonmetric)/coordinate (metric) relations with egocentric/allocentric frames of reference (in verbal and visuomotor conditions). RESULTS M.S.s performance was compared with that of NCs by means of a modified t test to small control sample size. M.S. met difficulty in positional processing and binding but not in object recognition. M.S. showed a selective deficit in the coordinate component in verbal (combined with both egocentric and allocentric frames) and visuomotor (only with the egocentric frame) spatial judgment tasks. In contrast, the categorical component looked always preserved in both frames of reference. CONCLUSIONS The left posteromedial brain areas contribute in combining and translating metric relations according to frames of reference and in using these representations to guide actions according to an egocentric perspective.

Does blindness affect egocentric and allocentric frames of reference in small and large scale spaces

There is evidence that early deprivation of vision prompts the use of body-based, egocentric spatial representations in congenitally blind individuals, whereas previous visual experience favors the use of object-based, allocentric representations (e.g. Pasqualotto A, Spiller MJ, Jansari AS, Proulx MJ. Visual experience facilitates allocentric spatial representation. Behav Brain Res 2013;236:175-79). Here we investigated whether the influence of the visual status on the capacity to represent egocentric and allocentric spatial relations is mediated by the scale of space explored: large-scale (where a haptic+locomotor exploration is required) and small-scale space (where haptic exploration is needed). Our results showed that congenitally blind people had more difficulty in representing spatial information allocentrically with respect to late blind and sighted individuals, but this difficulty was stronger with large-scale than small-scale space. Instead, egocentric performance was better than the allocentric one for all groups, particularly in the small scale condition. These results suggest that visual experience is necessary to develop accurate allocentric representations especially of large-scale spaces. This is probably due to its capacity to convey a large amount of spatial information simultaneously and to its role on the setting up of multisensory brain areas underlying spatial cognition. In the absence of any kind of visual experience, egocentric spatial representations are favored, especially in small-scale space, when the body offers a stable anchor point.

Near or far? It depends on my impression: Moral information and spatial behavior in virtual interactions

Near body distance is a key component of action and social interaction. Recent research has shown that peripersonal space (reachability-distance for acting with objects) and interpersonal space (comfort-distance for interacting with people) share common mechanisms and reflect the social valence of stimuli. The social psychological literature has demonstrated that information about morality is crucial because it affects impression formation and the intention to approach-avoid others. Here we explore whether peripersonal/interpersonal spaces are modulated by moral information. Thirty-six participants interacted with male/female virtual confederates described by moral/immoral/neutral sentences. The modulation of body space was measured by reachability-distance and comfort-distance while participants stood still or walked toward virtual confederates. Results showed that distance expanded with immorally described confederates and contracted with morally described confederates. This pattern was present in both spaces, although it was stronger in comfort-distance. Consistent with an embodied cognition approach, the findings suggest that high-level socio-cognitive processes are linked to sensorimotor-spatial processes.