Francesco Ruotolo

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.

The Effects of Vision-Related Aspects on Noise Perception of Wind Turbines in Quiet Areas

Preserving the soundscape and geographic extension of quiet areas is a great challenge against the wide-spreading of environmental noise. The E.U. Environmental Noise Directive underlines the need to preserve quiet areas as a new aim for the management of noise in European countries. At the same time, due to their low population density, rural areas characterized by suitable wind are considered appropriate locations for installing wind farms. However, despite the fact that wind farms are represented as environmentally friendly projects, these plants are often viewed as visual and audible intruders, that spoil the landscape and generate noise. Even though the correlations are still unclear, it is obvious that visual impacts of wind farms could increase due to their size and coherence with respect to the rural/quiet environment. In this paper, by using the Immersive Virtual Reality technique, some visual and acoustical aspects of the impact of a wind farm on a sample of subjects were assessed and analyzed. The subjects were immersed in a virtual scenario that represented a situation of a typical rural outdoor scenario that they experienced at different distances from the wind turbines. The influence of the number and the colour of wind turbines on global, visual and auditory judgment were investigated. The main results showed that, regarding the number of wind turbines, the visual component has a weak effect on individual reactions, while the colour influences both visual and auditory individual reactions, although in a different way.

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

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.

The relationship between allocentric and egocentric frames of reference and categorical and coordinate spatial information processing

We report two experiments on the relationship between allocentric/egocentric frames of reference and categorical/coordinate spatial relations. Jager and Postma (2003) suggest two theoretical possibilities about their relationship: categorical judgements are better when combined with an allocentric reference frame and coordinate judgements with an egocentric reference frame (interaction hypothesis); allocentric/egocentric and categorical/coordinate form independent dimensions (independence hypothesis). Participants saw stimuli comprising two vertical bars (targets), one above and the other below a horizontal bar. They had to judge whether the targets appeared on the same side (categorical) or at the same distance (coordinate) with respect either to their body-midline (egocentric) or to the centre of the horizontal bar (allocentric). The results from Experiment 1 showed a facilitation in the allocentric and categorical conditions. In line with the independence hypothesis, no interaction effect emerged. To see whether the results were affected by the visual salience of the stimuli, in Experiment 2 the luminance of the horizontal bar was reduced. As a consequence, a significant interaction effect emerged indicating that categorical judgements were more accurate than coordinate ones, and especially so in the allocentric condition. Furthermore, egocentric judgements were as accurate as allocentric ones with a specific improvement when combined with coordinate spatial relations. The data from Experiment 2 showed that the visual salience of stimuli affected the relationship between allocentric/egocentric and categorical/coordinate dimensions. This suggests that the emergence of a selective interaction between the two dimensions may be modulated by the characteristics of the task.

The effect of age on egocentric and allocentric spatial frames of reference

IntroductionLittle is known about the developmental course of spatialmemory, although this topic would be of clinical andtheoretical relevance. Spatial memory plays a fundamentalrole in everyday human activities, like way-finding, local-izing places or grasping objects. The assessment of spatialmemory, that is the pre-requisite of independent mobilityin the environment, is therefore crucial to monitor elderlypeople’s well-being.The purpose of this research is to investigate the effectof ageing on the frames of reference necessary to representspatial information in memory. Frames of reference areusually divided into egocentric and allocentric. Egocentricframes define spatial information with respect to the bodyor its parts, while allocentric frames specify spatial infor-mation on the basis of external objects (Kosslyn 1994).So far, age-related changes in basic visuospatial abili-ties, mental imagery and navigational abilities have beeninvestigated (see Ruggiero et al. 2008; Iachini et al. 2005).Laboratory-based psychometric tasks, such as mentalrotation, and more ecological tasks, such as direction-finding and map learning have been used (Barrash 1994;Wilkniss et al. 1997; Kirasic 1991). The results obtainedare still controversial and it is not yet clear which spatialprocesses decline with normal ageing and which ones arepreserved. Furthermore, deficits in spatial cognition, suchas topographical disorientation (Aguirre and D’Esposito1999), may be symptoms of age-related diseases likeAlzheimer’s disease.As regards the egocentric/allocentric distinction, to thebest of our knowledge the literature on ageing and spatialmemory has not directly addressed this issue. Few attemptsto compare directly these two kinds of processing in youngpeople with behavioural data (Iachini and Ruggiero 2006)and fMRI acquisition (Committeri et al. 2004), and withfocal brain-damaged patients (Iachini et al. 2009a) havebeen made. Parkin et al. (1995) used a spatial discrimina-tion task that involved egocentric spatial memory tocompare healthy elderly and young people. They found nosignificant negative effect of age on the spatial perfor-mance, but only a slight decline. Instead, Hort et al. (2007)compared healthy elderly and patients with mild cognitiveimpairment (MCI) and with Alzheimer’s disease (AD) on anavigational task that involved either egocentric or allo-centric components. Interestingly, they found a significantdeficit in the allocentric component in patients but not inhealthy elderly people.In this research healthy participants aged from 20 to89 years were submitted to a spatial task that compareddirectly the capacitytouseegocentric andallocentricframesofreference.Thiswasachievedbymanipulatingtheframeofreference required to give distance judgements. Further, thetask allowed to investigate the performance in far and nearspaces by varying the distance between the viewer and theobjects. In humans, egocentric frames of reference representthe primary interface between the organism and the envi-ronment (e.g. Millar 1994). For this reason, we expected afaster and more accurate egocentric than allocentric perfor-mance. As regards the effect of ageing, two outcomes arepossible: a negative influence on both spatial components ora selective drop in one of them. In the second case, an ego-centric decrease would be more likely (see Hort et al. 2007).

Motor resources in peripersonal space are intrinsic to spatial encoding: Evidence from motor interference

The aim of this study was to explore the role of motor resources in peripersonal space encoding: are they intrinsic to spatial processes or due to action potentiality of objects? To answer this question, we disentangled the effects of motor resources on object manipulability and spatial processing in peripersonal and extrapersonal spaces. Participants had to localize manipulable and non-manipulable 3-D stimuli presented within peripersonal or extrapersonal spaces of an immersive virtual reality scenario. To assess the contribution of motor resources to the spatial task a motor interference paradigm was used. In Experiment 1, localization judgments were provided with the left hand while the right dominant arm could be free or blocked. Results showed that participants were faster and more accurate in localizing both manipulable and non-manipulable stimuli in peripersonal space with their arms free. On the other hand, in extrapersonal space there was no significant effect of motor interference. Experiment 2 replicated these results by using alternatively both hands to give the response and controlling the possible effect of the orientation of object handles. Overall, the pattern of results suggests that the encoding of peripersonal space involves motor processes per se, and not because of the presence of manipulable stimuli. It is argued that this motor grounding reflects the adaptive need of anticipating what may happen near the body and preparing to react in time.

Frames of reference and categorical and coordinate spatial relations: a hierarchical organisation

This research is about the role of categorical and coordinate spatial relations and allocentric and egocentric frames of reference in processing spatial information. To this end, we asked whether spatial information is firstly encoded with respect to a frame of reference or with respect to categorical/coordinate spatial relations. Participants had to judge whether two vertical bars appeared on the same side (categorical) or at the same distance (coordinate) with respect to the centre of a horizontal bar (allocentric) or with respect to their body midline (egocentric). The key manipulation was the timing of the instructions: one instruction (reference frame or spatial relation) was given before stimulus presentation, the other one after. If spatial processing requires egocentric/allocentric encoding before coordinate/categorical encoding, then spatial judgements should be facilitated when the frame of reference is specified in advance. In contrast, if categorical and coordinate dimensions are primary, then a facilitation should appear when the spatial relation is specified in advance. Results showed that participants were more accurate and faster when the reference frame rather than the type of spatial relation was provided before stimulus presentation. Furthermore, a selective facilitation was found for coordinate and categorical judgements after egocentric and allocentric cues, respectively. These results suggest a hierarchical structure of spatial information processing where reference frames play a primary role and selectively interact with subsequent processing of spatial relations.

The influence of anxiety and personality factors on comfort and reachability space: a correlational study

Abstract Although the effects of several personality factors on interpersonal space (i.e. social space within personal comfort area) are well documented, it is not clear whether they also extend to peripersonal space (i.e. reaching space). Indeed, no study has directly compared these spaces in relation to personality and anxiety factors even though such a comparison would help to clarify to what extent they share similar mechanisms and characteristics. The aim of the present paper was to investigate whether personality dimensions and anxiety levels are associated with reaching and comfort distances. Seventy university students (35 females) were administered the Big Five Questionnaire and the State-Trait Anxiety Inventory; afterwards, they had to provide reachability- and comfort-distance judgments towards human confederates while standing still (passive) or walking towards them (active). The correlation analyses showed that both spaces were positively related to anxiety and negatively correlated with the Dynamism in the active condition. Moreover, in the passive condition higher Emotional Stability was related to shorter comfort distance, while higher cognitive Openness was associated with shorter reachability distance. The implications of these results are discussed.

Sequential vs simultaneous encoding of spatial information: a comparison between the blind and the sighted.

The aim of this research is to assess whether the crucial factor in determining the characteristics of blind peoples spatial mental images is concerned with the visual impairment per se or the processing style that the dominant perceptual modalities used to acquire spatial information impose, i.e. simultaneous (vision) vs sequential (kinaesthesis). Participants were asked to learn six positions in a large parking area via movement alone (congenitally blind, adventitiously blind, blindfolded sighted) or with vision plus movement (simultaneous sighted, sequential sighted), and then to mentally scan between positions in the path. The crucial manipulation concerned the sequential sighted group. Their visual exploration was made sequential by putting visual obstacles within the pathway in such a way that they could not see simultaneously the positions along the pathway. The results revealed a significant time/distance linear relation in all tested groups. However, the linear component was lower in sequential sighted and blind participants, especially congenital. Sequential sighted and congenitally blind participants showed an almost overlapping performance. Differences between groups became evident when mentally scanning farther distances (more than 5m). This threshold effect could be revealing of processing limitations due to the need of integrating and updating spatial information. Overall, the results suggest that the characteristics of the processing style rather than the visual impairment per se affect blind peoples spatial mental images.