The pusher syndrome reverses the orienting bias caused by spatial neglect

Spatial neglect can be accompanied by a pusher syndrome (PS) which is characterized by a postural deviation towards the contralesional side. In this study, the representation of the body orientation in the horizontal plane was evaluated in neglect patients with and without PS. The participants had to align a luminous rod with the straight ahead direction, a method allowing the measure of both horizontal components of subjective straight ahead, i.e. lateral shift and yaw rotation. Eighteen patients with a lesion of the right hemisphere were compared with ten healthy participants. Patients had neglect and PS (P+N+; n=3), neglect only (P-N+; n=10), or neither neglect nor PS (P-N-; n=5). P+N+ patients showed a significant leftward shift contrasting with the rightward shift of P-N+. No shift occurred in patients without neglect and controls. No significant yaw error was recorded in any groups. The original result of this study was an inversion of the sign of the bias in neglect patients with PS. This could be related to the postural disorders characterizing this syndrome, and which are opposite to those usually observed in spatial neglect. Thus, these data suggest a link between disorders of spatial representations and disorders of posture

Influence of spatial neglect, hemianopia and hemispace on the subjective vertical

The perception of the vertical is frequently shifted to the contralesional side in patients with hemispheric lesions, and this is amplified by spatial neglect. However, we do not know the specific influence of hemianopia and space of perception on this phenomenon. Here, we analyzed the respective influences of spatial neglect, hemianopia and hemispace on the subjective vertical in patients with right hemispheric stroke. Twelve neglect patients with and 5 without hemianopia were compared to 3 non-neglect patients with and 13 without hemianopia. They had to match a luminous rod to the vertical, either in the mid-sagittal plane or in the right or the left hemispace. Patients showed a counter-clockwise deviation, and this was exaggerated by both neglect and hemianopia. In patients with neglect, the error was greater in the left hemispace. In conclusion, neglect and hemianopia had additive effects on the contralesional bias of the subjective vertical

Hemianopia and neglect influence on straight-ahead perception

In spatial neglect, the pathological ipsilesional deviation of the subjective straight ahead (SSA) received both 'translational' and 'rotational' interpretations. Furthermore, hemianopia per se could also influence straight-ahead (SA) perception. Here, we aimed at disentangling the relative effects of neglect and hemianopia on the SSA by using a method analyzing translation and rotation in parallel. We included patients with a right hemisphere stroke. Ten had neglect and hemianopia, 6 neglect only, 3 hemianopia only, and 12 neither one nor the other. 15 were controls. Participants had to adjust a bar, movable in translation and rotation, SA of the navel, in darkness. Patients with spatial neglect showed systematic rightward translation, greater when hemianoptic. The rotation component appeared more variable and was influenced by the presence of a visual field defect, as most of the patients with hemianopia showed an anticlockwise rotation and most of the patients without hemianopia a clockwise rotation. Non-neglect patients and control subjects demonstrated a fair performance level. In conclusion, both neglect and hemianopia resulted in a translation error of the SSA to the ipsilesional side. In neglect patients, additional hemianopia resulted in a counterclockwise rotation. Furthermore, rotation and translation errors appeared dissociated, suggesting a different coding of these dimensions by the right posterior hemisphere

Hemianopia and neglect influence on straight-ahead perception

In spatial neglect, the pathological ipsilesional deviation of the subjective straight ahead (SSA) received both 'translational' and 'rotational' interpretations. Furthermore, hemianopia per se could also influence straight-ahead (SA) perception. Here, we aimed at disentangling the relative effects of neglect and hemianopia on the SSA by using a method analyzing translation and rotation in parallel. We included patients with a right hemisphere stroke. Ten had neglect and hemianopia, 6 neglect only, 3 hemianopia only, and 12 neither one nor the other. 15 were controls. Participants had to adjust a bar, movable in translation and rotation, SA of the navel, in darkness. Patients with spatial neglect showed systematic rightward translation, greater when hemianoptic. The rotation component appeared more variable and was influenced by the presence of a visual field defect, as most of the patients with hemianopia showed an anticlockwise rotation and most of the patients without hemianopia a clockwise rotation. Non-neglect patients and control subjects demonstrated a fair performance level. In conclusion, both neglect and hemianopia resulted in a translation error of the SSA to the ipsilesional side. In neglect patients, additional hemianopia resulted in a counterclockwise rotation. Furthermore, rotation and translation errors appeared dissociated, suggesting a different coding of these dimensions by the right posterior hemisphere

Mislocalization of tactile stimuli applied to the trunk in spatial neglect

In patients with spatial neglect, body perception and representation are impaired - especially the projection of the anterior body midline in anterior space (the subjective "straight ahead"). However, data on more lateral body parts and the posterior body surface are scarce. We explored deviations of the perception of different body points located to the left or right of the midline and on the anterior and posterior body surfaces, and their lesion correlates in right hemisphere stroke patients

Time since stroke influences the impact of hemianopia and spatial neglect on visual-spatial tasks

Spatial neglect results in an ipsilesional misorientation of attention in visual-spatial tasks. Hemianopia impairs visual perception but its influence on visual-spatial tasks is subject to debate. Here, we investigated the influence of the time since stroke on the respective impacts of hemianopia and spatial neglect

Reducing rightward bias of subjective straight ahead in neglect patients by changes in body orientation

The subjective straight ahead (SSA), a measure of the representation of body orientation, has been shown to be shifted to the lesion side in neglect patients, and to be influenced by stimulation of sensory systems involved in postural control

Incidence, Risk Factors and Anatomy of Peripersonal Visuospatial Neglect in Acute Stroke

The study aims to describe the epidemiology and the neural correlates of peripersonal visuospatial neglect (PVN)in patients admitted to the Geneva Stroke Unit for an acute stroke or a transient ischemic attack (TI

An immersive virtual reality tool for assessing left and right unilateral spatial neglect

The reported rate of the occurrence of unilateral spatial neglect (USN) is highly variable likely due to the lack of validity and low sensitivity of classical tools used to assess it. Virtual reality (VR) assessments try to overcome these limitations by proposing immersive and complex environments. Nevertheless, existing VR‐based tasks are mostly focused only on near space and lack analysis of psychometric properties and/or clinical validation. The present study evaluates the clinical validity and sensitivity of a new immersive VR‐based task to assess USN in the extra‐personal space and examines the neuronal correlates of deficits of far space exploration. The task was administrated to two groups of patients with right ( N = 28) or left ( N = 11) hemispheric brain lesions, also undergoing classical paper‐and‐pencil assessment, as well as a group of healthy participants. Our VR‐based task detected 44% of neglect cases compared to 31% by paper‐and‐pencil tests in the total sample. Importantly, 30% of the patients (with right or left brain lesions) with no clear sign of USN on the paper‐and‐pencil tests performed outside the normal range in the VR‐based task. Voxel lesion‐symptom mapping revealed that deficits detected in VR were associated with lesions in insular and temporal cortex, part of the neural network involved in spatial processing. These results show that our immersive VR‐based task is efficient and sensitive in detecting mild to strong manifestations of USN affecting the extra‐personal space, which may be undetected using standard tools

Real-time fMRI and EEG neurofeedback: A perspective on applications for the rehabilitation of spatial neglect

Spatial neglect is a neuropsychological syndrome characterized by a failure to orient, perceive, and act toward the contralesional side of the space after brain injury. Neglect is one of the most frequent and disabling neuropsychological syndromes following right-hemisphere damage, often persisting in the chronic phase and responsible for a poor functional outcome at hospital discharge. Different rehabilitation approaches have been proposed over the past 60 years, with a variable degree of effectiveness. In this point-of-view article, we describe a new rehabilitation technique for spatial neglect that directly targets brain activity and pathological physiological processes: namely, neurofeedback (NFB) with real-time brain imaging methodologies. In recent proof-of-principle studies, we have demonstrated the potential of this rehabilitation technique. Using real-time functional MRI (rt-fMRI) NFB in chronic neglect, we demonstrated that patients are able to upregulate their right visual cortex activity, a response that is otherwise reduced due to losses in top-down attentional signals. Using real-time electroencephalography NFB in patients with acute or chronic condition, we showed successful regulation with partial restoration of brain rhythm dynamics over the damaged hemisphere. Both approaches were followed by mild, but encouraging, improvement in neglect symptoms. NFB techniques, by training endogenous top-down modulation of attentional control on sensory processing, might induce sustained changes at both the neural and behavioral levels, while being non-invasive and safe. However, more properly powered clinical studies with control groups and longer follow-up are needed to fully establish the effectiveness of the techniques, identify the most suitable candidates, and determine how the techniques can be optimized or combined in the context of rehabilitation