Travel Planning Ability in Right Brain-Damaged Patients: Two Case Reports

Planning ability is fundamental for goal-directed spatial navigation. Preliminary findings from patients and healthy individuals suggest that travel planning (TP)—namely, navigational planning—can be considered a distinct process from visuospatial planning (VP) ability. To shed light on this distinction, two right brain-damaged patients without hemineglect were compared with a control group on two tasks aimed at testing VP (i.e., Tower of London-16, ToL-16) and TP (i.e., Minefield Task, MFT). The former requires planning the moves to reach the right configuration of three colored beads on three pegs, whereas the latter was opportunely developed to assess TP in the navigational environment when obstacles are present. Specifically, the MFT requires participants to plan a route on a large carpet avoiding some hidden obstacles previously observed. Patient 1 showed lesions encompassing the temporoparietal region and the insula; she performed poorer than the control group on the ToL-16 but showed no deficit on the MFT. Conversely, Patient 2 showed lesions mainly located in the occipitoparietal network of spatial navigation; she performed worse than the control group on the MFT but not on the ToL-16. In both cases performances satisfied the criteria for a classical dissociation, meeting criteria for a double dissociation. These results support the idea that TP is a distinct ability and that it is dissociated from VP skills

Spatio-Temporal Features of Visual Exploration in Unilaterally Brain-Damaged Subjects with or without Neglect: Results from a Touchscreen Test

Cognitive assessment in a clinical setting is generally made by pencil-and-paper tests, while computer-based tests enable the measurement and the extraction of additional performance indexes. Previous studies have demonstrated that in a research context exploration deficits occur also in patients without evidence of unilateral neglect at pencil-and-paper tests. The objective of this study is to apply a touchscreen-based cancellation test, feasible also in a clinical context, to large groups of control subjects and unilaterally brain-damaged patients, with and without unilateral spatial neglect (USN), in order to assess disturbances of the exploratory skills. A computerized cancellation test on a touchscreen interface was used for assessing the performance of 119 neurologically unimpaired control subjects and 193 patients with unilateral right or left hemispheric brain damage, either with or without USN. A set of performance indexes were defined including Latency, Proximity, Crossings and their spatial lateral gradients, and Preferred Search Direction. Classic outcome scores were computed as well. Results show statistically significant differences among groups (assumed p<0.05). Right-brain-damaged patients with USN were significantly slower (median latency per detected item was 1.18 s) and less efficient (about 13 search-path crossings) in the search than controls (median latency 0.64 s; about 3 crossings). Their preferred search direction (53.6% downward, 36.7% leftward) was different from the one in control patients (88.2% downward, 2.1% leftward). Right-brain-damaged patients without USN showed a significantly abnormal behavior (median latency 0.84 s, about 5 crossings, 83.3% downward and 9.1% leftward direction) situated half way between controls and right-brain-damaged patients with USN. Left-brain-damaged patients without USN were significantly slower and less efficient than controls (latency 1.19 s, about 7 crossings), preserving a normal preferred search direction (93.7% downward). Therefore, the proposed touchscreen-based assessment had evidenced disorders in spatial exploration also in patients without clinically diagnosed USN

Visuospatial neglect after stroke:heterogeneity, diagnosis and treatment.

The general objective of this thesis was to better understand and treat visuospatial neglect, a frequent and disabling disorder in lateralized attention. The first aim was to further unravel visuospatial neglect by focusing on several subtypes. In neglect research, mostly patients with left-sided neglect are included. Knowledge regarding neglect is, therefore, mainly based on a subset of patients. This is unfortunate, however, as our study showed that left- and right-sided neglect are both common after stroke. Furthermore, both patients with left- and right-sided neglect are less independent in mobility and self-care. It is, therefore, of great importance to adequately diagnose and treat both subtypes. Another subtype regards region-specific neglect. We studied neural substrates of peripersonal (i.e. within arm length) and extrapersonal (i.e. beyond arm length) neglect, and found that several right temporal and thalamic regions were related to both peripersonal and extrapersonal neglect, and several additional right temporal, parietal and occipital regions were only related to extrapersonal neglect. None of the brain regions were only related to peripersonal neglect. It seems that mostly shared anatomical regions are related to peripersonal and extrapersonal neglect. Today’s diagnosis of neglect lacks sensitivity, and discrepancies exist between performance on paper-and-pencil tasks and patient functioning in daily life. This is problematic for accurate diagnosis of neglect and for proper evaluation of rehabilitation interventions. We evaluated a dynamic multitask to assess neglect in a sensitive manner: the Mobility Assessment Course. An association existed between performance on the Mobility Assessment Course and performance on standard paper-and-pencil neglect tasks. Especially patients who were ‘recovered’, based on the paper-and-pencil tasks, showed neglect during the Mobility Assessment Course. This fits the hypothesis that this task may detect neglect in patients who do not show neglect during standard paper-and-pencil tasks. Next, we evaluated the potential of digitized neuropsychological testing. Next to the attentional bias, other cognitive processes that may relate to attention can be evaluated in more detail, such as search organization, involved in many daily processes and often disturbed after stroke. We studied search organization in stroke patients and found that, although disorganized search is related to neglect, this is only a weak relation, and it might be a separate cognitive construct. We conclude that analysing measures of search provides useful additional insights into the lower-order visuospatial processes of stroke patients. Finally, we evaluated the long-term effects of early treatment with prism adaptation compared to sham adaptation on neglect behaviour in daily life.Both patient groups (i.e., receiving sham adaptation and prism adaptation) improved on dynamic and static outcome measures of neglect. However, no differences were seen between groups. One of the main reasons for these neutral results could relate to the heterogeneity of the disorder, enhanced by the spontaneous neurobiological recovery in especially the subacute phase post-stroke onset or standard treatment effects (care as usual). They could have overshadowed the potential effects of prism adaptation. To conclude, prism adaptation is not effective for all patients with neglect, and, based on these results, should not be implemented in clinical practice

Cognitive and anatomical correlates of neglect for peripersonal and extrapersonal space

Spatial neglect is a neurological disorder where patients typically fail to orient or respond to events on their left side. Moreover, recent studies suggest that the severity of neglect may depend specifically on whether stimuli are presented within or beyond arm's reach. However, the evidence for such a general functional dissociation between near and far space processing in the brain remains conflicting: The majority of research has been focussed on line bisection errors which reflect only one small aspect of neglect behaviour. In addition, some behavioural findings suggest a functional dissociation only if a motor response is required. Finally, to date, the critical areas involved in distance related space processing have not been identified.Thus, it remains not only unclear whether neglect in near and far space is a task- and response independent phenomenon but also which damaged brain areas impair distance related space processing. In order to answer these questions the present study compared line bisection and visual search performance and its anatomical correlates in near and far space by using a combined single case- and group study approach.The results showed that neglect restricted to near or far space can vary not only depending on the type of task but also on the type of response required. Visual search tasks were particularly sensitive in detecting the dissociation between those two space sectors. Anatomically, neglect for near space was mainly associated with occipito-parietal lesions and medio-temporal structures, including the posterior cingulate. Neglect for far space was found to result from focal damage of medial, ventro-temporal structures and the prefrontal cortex. In conclusion, neglect for near and far space does not seem to result from a general impairment in distance related processing but from a combination of factors related to specific task demands as well as the location and extent of the brain damage

Design and Development of ReMoVES Platform for Motion and Cognitive Rehabilitation

Exergames have recently gained popularity and scientific reliability in the field of assistive computing technology for human well-being. The ReMoVES platform, developed by the author, provides motor and cognitive exergames to be performed by elderly or disabled people, in conjunction with traditional rehabilitation. Data acquisition during the exercise takes place through Microsoft Kinect, Leap Motion and touchscreen monitor. The therapist is provided with feedback on patients' activity over time in order to assess their weakness and correct inaccurate movement attitudes. This work describes the technical characteristics of the ReMoVES platform, designed to be used by multiple locations such as rehabilitation centers or the patient's home, while providing a centralized data collection server. The system includes 15 exergames, developed from scratch by the author, with the aim of promoting motor and cognitive activity through patient entertainment. The ReMoVES platform differs from similar solutions for the automatic data processing features in support of the therapist. Three methods are presented: based on classic data analysis, on Support Vector Machine classification, and finally on Recurrent Neural Networks. The results describe how it is possible to discern patient gaming sessions with adequate performance from those with incorrect movements with an accuracy of up to 92%. The system has been used with real patients and a data database is made available to the scientific community. The aim is to encourage the dissemination of such data to lay the foundations for a comparison between similar studies

The Impact of Expertise in Archery on the Attentional Biases of Perceptual and Representational Pseudoneglect

Turnbull & McGeorge (1998) asked a group of participants if they had bumped into anything recently and if so, on what side? Results reflected a trend towards bumping on the right. This tendency to bump into objects on the right has since been observed in a naturalistic setting (Nicholls, Loftus, Meyer, & Mattingley, 2007). But rather than an interesting quirk of statistics these studies, and many others have captured a phenomenon called pseudoneglect (Bowers and Heilman, 1980). It represents a subtle yet consistent bias in our spatial attention towards the left half of space and away from the right which results in the pattern of bumping or other lateralised errors seen in the spatial attention literature (See Jewell & McCourt, 2000). Furthermore, this bias does not just impact the perceptual sphere; it also crosses into the representational, impacting our memory for visual information (Bisiach & Luzatti, 1987). But whether this is consistent in individuals who are trained in an accuracy based sport remains unknown. The current research sought to examine perceptual and representational pseudoneglect effects in a group of expert archers compared to neurologically healthy controls. Results suggest that the attainment of expert level in archery is associated with reduced perceptual pseudoneglect. Archers showed a trend towards reduced representational pseudoneglect but this was non-significant. Results are discussed in line with theoretical frameworks of visual attention, pseudoneglect and expertise