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Pathological embodiment (E+) is a specific contralesional delusion of body ownership, observed following brain damage, in which patients embody someone else’s arm and its movements within their own body schema whenever the contralesional ‘alien’ arm is presented in a body-congruent position (i.e., 1st person perspective and aligned with the patient’s shoulder). This disorder is often associated with spatial neglect, a neurological syndrome in which patients are unaware of stimuli presented in the contralesional (often the left) space. Capitalizing on previous evidence demonstrating that prismatic adaptation of the ipsilesional arm to right-deviating prisms is effective in ameliorating neglect symptoms, here we investigated whether such amelioration also occurs in E+ patients with neglect when prismatic training is performed by the ‘alien’ embodied arm. Four left neglect patients (one with and three without pathological embodiment) underwent visuomotor prismatic training performed by an ‘alien’ arm. Specifically, while patients were wearing prismatic goggles shifting the visual field rightward, a co-experimenter’s left arm presented in a body-congruent perspective was repeatedly moved toward visual targets by another examiner. In a control condition, the co-experimenter’s arm was moved toward the targets from a body-incongruent position (i.e., 3rd person perspective). Neglect symptoms were assessed before and after training through paper-and-pencil tasks. In the E+ patient, neglect improved significantly more in 1st than in 3rd person perspective training, suggesting that prismatic adaptation of the ‘alien’ embodied arm is effective in modulating spatial representation. Conversely, for control E- patients (not embodying the ‘alien’ arm), we observed more limited improvements following training. These findings indicate that the ‘alien’ embodied arm is so deeply embedded in the patient body and motor schema that adaptation to prismatic lenses can affect multiple processing stages, from low level sensory-motor correspondences, to higher level body, motor and spatial maps, similarly as it occurs in normal subjects and neglect patients without pathological embodiment.

Pathological embodiment (E+) is a specific contralesional delusion of body ownership, observed following brain damage, in which patients embody someone else's arm and its movements within their own body schema whenever the contralesional 'alien' arm is presented in a body-congruent position (i.e., 1st person perspective and aligned with the patient's shoulder). This disorder is often associated with spatial neglect, a neurological syndrome in which patients are unaware of stimuli presented in the contralesional (often the left) space. Capitalizing on previous evidence demonstrating that prismatic adaptation of the ipsilesional arm to right-deviating prisms is effective in ameliorating neglect symptoms, here we investigated whether such amelioration also occurs in E+ patients with neglect when prismatic training is performed by the 'alien' embodied arm. Four left neglect patients (one with and three without pathological embodiment) underwent visuomotor prismatic training performed by an 'alien' arm. Specifically, while patients were wearing prismatic goggles shifting the visual field rightward, a co-experimenter's left arm presented in a body-congruent perspective was repeatedly moved toward visual targets by another examiner. In a control condition, the co-experimenter's arm was moved toward the targets from a body-incongruent position (i.e., 3rd person perspective). Neglect symptoms were assessed before and after training through paper-and-pencil tasks. In the E+ patient, neglect improved significantly more in 1st than in 3rd person perspective training, suggesting that prismatic adaptation of the 'alien' embodied arm is effective in modulating spatial representation. Conversely, for control E- patients (not embodying the 'alien' arm), we observed more limited improvements following training. These findings indicate that the 'alien' embodied arm is so deeply embedded in the patient body and motor schema that adaptation to prismatic lenses can affect multiple processing stages, from low level sensory-motor correspondences, to higher level body, motor and spatial maps, similarly as it occurs in normal subjects and neglect patients without pathological embodiment. [ABSTRACT FROM AUTHOR]

We developed a functional semi-structured scale to observe Hemineglect symptoms in Activities of Daily Living (H-ADL). The scale could assist clinicians in assessing rehabilitation priorities aimed at correcting any persisting errors or omissions. In addition, the scale could also be used by caregivers to observe patients’ progress and improve their participation. Two groups of right brain-damaged patients (25 with hemineglect; 27 without hemineglect) were tested twice: at admission and before discharge from hospital. A control group of healthy individuals matched to patients for age and education and patients’ caregivers also participated. Two raters (A; B), experts in neuropsychology, observed patients and healthy individuals using the H-ADL. We found that the H-ADL final scores correlated with the standard hemineglect tests. The three groups differed in performance and differences also emerged between the first and the second assessment, suggesting an improvement due to the remission of hemineglect as a consequence of the treatment. Raters A and B did not differ in their observations, but there were some discrepancies with caregivers’ observations. Therefore, although caregivers could help clinicians in detecting persistent hemineglect behaviour, the assessment should be performed by experts in neuropsychology. [ABSTRACT FROM PUBLISHER]

Abstract: Right hemisphere damage often provokes signs of visual neglect, characterized by a prominent left–right imbalance in information processing. Neglect patients are biased towards right-sided objects and ignore left-sided events. Left–right imbalance may not only result from left neglect but also from right attraction, which have been considered as, respectively, defective and productive phenomena in neglect patients. However, the relative contributions of these two mechanisms to the final left–right imbalance remain uncertain. Using a novel experimental paradigm, we were able to separately test the contribution of left neglect and right attraction to neglect behavior. We used horizontal and vertical lines implemented in L shapes in a line extension task. The use of L shapes oriented either to the left or to the right made it possible to measure the left bias by comparing the length of a left-sided horizontal line to that of a centered vertical line, and to measure the right bias by comparing a centered vertical to a rightwards horizontal line. Our results showed that, in this experimental set, the left–right discrepancy is supported more by left neglect than by right attraction, with important implications about the role of left–right competition on the deployment of left neglect and right attraction. [ABSTRACT FROM AUTHOR]

Abstract: Left visuo-spatial neglect is a well-recognized predictor of poor functional outcome following right hemisphere stroke. Over the past 60 years, 18 different methods have been described and evaluated aimed at reducing the effects of this impairment. Although there are some grounds for optimism particularly in terms of short-term impairment-based effects, the range and degree of disability borne by many patients remain high and the clinical effectiveness of the different methods viewed in terms of long-lasting functional improvement (i.e. improvement of disabilities or handicap) is not clear. A systematic review of the available clinically relevant literature, using comparative and stringent levels of evidence, indicates that visual scanning training (VST), trunk rotation (TR) or repeated neck muscle vibrations (NMV) when associated with an extensive training program, mental imagery training, video feedback training and prism adaptation (PA) can be recommended for the rehabilitation of patients with left neglect. More studies however are needed to determine the optimal paradigm of limb activation (LA) eliciting a sustained functional improvement. Sensory stimulations alone and Fresnel prisms do not appear to be functionally relevant. For the other methods, the actual literature is not sufficient to conclude whether or not a long-term functional improvement can be achieved. [Copyright &y& Elsevier]

Purpose: The current paper was designed to provide a critical overview on the different methods proposed for the rehabilitation of left spatial neglect. Methods: On the basis of a previous systematic review of the literature, we analyzed all articles available aiming at reducing left spatial neglect which included a long term functional assessment. Results: The aim of most early rehabilitation approaches, such as visuo-scanning training, was to re-orient visual scanning toward the neglected side. This review confirmed the utility of this method for rehabilitation purposes. More recent – theory driven – procedures, also based on a training approach, include limb activation, mental imagery training and video-feedback training. Although there is ground for optimism, the functional effectiveness of these methods still relies on few single-case studies. Newer methods have tried to stimulate automatic orientation of gaze or attention towards neglected space in a bottom-up fashion. Sensory stimulations can remove most of the classical signs of left neglect but their effects are short-lived. Such stimulations are not functionally relevant for rehabilitation except for trunk rotation or repeated neck muscle vibrations if they are associated with an extensive training program. A more promising intervention is prism adaptation given the growing evidence of relatively long-term functional gains from comparatively short term usage. Conclusion: Overall, there is now evidence for several clinically relevant long-term benefits in the case of visual scanning training, mental imagery training, video feedback training, neck muscle vibration and trunk rotation if associated with visual scanning training and prism adaptation. However, the amount of evidence is still limited to a small number of relevant published articles and it is mandatory to continue the research in this field. In this review, the possible routes for new rehabilitation procedures are discussed on the basis of the actual knowledge regarding the neuro-cognitive mechanisms underlying the therapeutic effect of prism adaptation. [ABSTRACT FROM AUTHOR]

Although the role of frontoparietal cortex in spatial egocentric processing is well established, recent animal-lesion and human functional imaging studies have suggested that the neostriatum may also be a critical modulator in the processing of body-centred spatial orientation. We describe here a patient with right putamen-centred hemorrhage who exhibited a consistent counterclockwise rotation of approximately 90° when drawing and writing from memory. A more detailed assessment with a series of representational clock tests demonstrated that the rotation was present only in tasks requiring the use of egocentric cues. In the absence of external cues the patient would adopt and maintain a stable but incorrectly-oriented egocentric representation of the imagined or recollected object. By contrast, performance could be rectified by presentation of correctly-oriented stimuli. These findings suggest that the putamen is part of a circuit underlying egocentric, as opposed to allocentric, representation of space in humans. [Copyright &y& Elsevier]

Three unilateral parietal patients were tested on their perception of biological motion, a special case of form-from-motion. Two patients had the lesion in the right, and one in the left parietal area. All patients could easily perform a classical form-from-motion task [Neuron 32 (2001) 985], but they were severely impaired in a visual search task using biological motion sequences. In particular, the left parietal patient showed a more severe loss. He was unable to identify even a single item. Overall our patients seemed to perform differently from the classical motion-blind patients described in the literature [Visual Cognition 3 (1996) 363; Eur. J. Neurol. 9 (2002) 463; Visual Neurosci. 5 (1990) 353] whose lesions included the visual cortical area V5. Since our patients’ low-level motion mechanisms are preserved, we suggest that the perception of biological motion relies on a high-level description of dynamic patterns [Cognition 80 (2001) 47], a mechanism that is impaired in parietal lobe patients. We discuss our results at the light of the recent theories suggesting that biological motion is performed by visual associative areas outside the classical motion pathways and that it is an active process dependent on attentional resources [Cognition 80 (2001) 47]. [Copyright &y& Elsevier]