Virtual environment training system for rehabilitation of stroke patients with unilateral neglect: crossing the virtual street.

In this paper, we propose a system for training of stroke patients with unilateral neglect by using technology of virtual reality (VR). The proposed system is designed to compensate for unilateral neglect. This system contains the calibration of unilateral neglect and the training of this disease. The calibration procedure is implemented by aligning the virtual object at a subjective middle line. The training procedure is implemented by completing the missions that are used to keep the virtual avatar safe during crossing the street in a virtual environment. The results of this study show that the proposed system is effective to train unilateral neglect. The left to right ratio scores extracted from this system gradually decrease as the sessions of training are repeated. To validate the VR system parameters, the parameters are analyzed by correlation with those of traditional unilateral neglect assessment methods (such as the line bisection test and the cancellation test).     

儿童忽视与同伴接受：消极社会行为的中介作用

运用问卷调查法和同伴提名法,考察小学4、5年级共503名儿童的消极社会行为（攻击行为、退缩行为、受欺负行为）、同伴接受和儿童忽视间的关系。结果发现,儿童忽视与退缩行为、受欺负行为之间存在显著正相关,与攻击行为之间相关不显著;儿童忽视与同伴接受有显著负相关。忽视通过消极社会行为的两组中介变量作用于儿童的同伴接受。     

Different patterns of dissociation in unilateral spatial neglect

The aim of this paper is to discuss the issue of dissociations found in unilateral spatial neglect according to the modality of space exploration and the nature of the task. For this purpose we present a reanalysis of the data from a recent paper of Gentilini et al. (1989) comparing visual and blindfolded exploration of a computer keyboard and discuss the performance of a left-brain-damaged patient with right visuospatial neglect and left-sided neglect dyslexia. We conclude that unilateral spatial neglect cannot be interpreted as a disruption of a single attentional mechanism, but rather it reflects impaired attentional mechanisms at several levels of cognitive processing.     

Spatial probability cuing and right hemisphere damage

In this experiment we studied statistical learning, inter-trial priming, and visual attention. We assessed healthy controls and right brain damaged (RBD) patients with and without neglect, on a simple visual discrimination task designed to measure priming effects and probability learning. All participants showed a preserved priming effect for item color. Contrary to healthy controls and RBD participants without neglect, RBD participants with neglect did not show positional priming and both RBD groups learned the underlying spatial probability distribution of target locations to a lesser degree. To see if the latter deficiency could be improved, we tested a patient with long standing chronic spatial neglect on three separate days and observed improved identification times for left sided, high probability, targets. In summary, we found preservation of priming per se in people with spatial neglect. However, this was only clearly demonstrable for color priming and not for positional priming. Associated with this impairment was a difficulty in learning the overall statistical structure of target locations. In a patient with severe persistent neglect we were able to demonstrate that the deficit in statistical learning was not absolute, as this subject improved his identification times for targets appearing in high probability regions of the test display.     

Spatial probability cuing and right hemisphere damage

In this experiment we studied statistical learning, inter-trial priming, and visual attention. We assessed healthy controls and right brain damaged (RBD) patients with and without neglect, on a simple visual discrimination task designed to measure priming effects and probability learning. All participants showed a preserved priming effect for item color. Contrary to healthy controls and RBD participants without neglect, RBD participants with neglect did not show positional priming and both RBD groups learned the underlying spatial probability distribution of target locations to a lesser degree. To see if the latter deficiency could be improved, we tested a patient with long standing chronic spatial neglect on three separate days and observed improved identification times for left sided, high probability, targets. In summary, we found preservation of priming per se in people with spatial neglect. However, this was only clearly demonstrable for color priming and not for positional priming. Associated with this impairment was a difficulty in learning the overall statistical structure of target locations. In a patient with severe persistent neglect we were able to demonstrate that the deficit in statistical learning was not absolute, as this subject improved his identification times for targets appearing in high probability regions of the test display.     

Base-rate respect: From ecological rationality to dual processes

The phenomenon of base-rate neglect has elicited much debate. One arena of debate concerns how people make judgments under conditions of uncertainty. Another more controversial arena concerns human rationality. In this target article, we attempt to unpack the perspectives in the literature on both kinds of issues and evaluate their ability to explain existing data and their conceptual coherence. From this evaluation we conclude that the best account of the data should be framed in terms of a dual-process model of judgment, which attributes base-rate neglect to associative judgment strategies that fail to adequately represent the set structure of the problem. Base-rate neglect is reduced when problems are presented in a format that affords accurate representation in terms of nested sets of individuals.     

Illusory hand ownership in a patient with personal neglect for the upper limb,but no somatoparaphenia

The symptoms of patients with left personal neglect are characterized by inattention towards contralesional (left) body parts while at the same time explicitly ascertaining ownership for the neglected hemibody. It is currently unknown if personal neglect is associated with more subtle or implicit disturbances of own body perception and body ownership as measured with the rubber hand illusion. In this study, we report data from a patient with a right hemispheric lesion and personal neglect, without associated somatosensory deficits. We administered to the patient (and to 12 age‐matched controls) the rubber hand illusion paradigm to the right and left hands, to elicit illusory ownership for a fake hand, before and after recovery from personal neglect for the left arm. In a first session, run when the patient showed personal neglect affecting the left arm, he experienced a significantly enhanced subjective illusion of embodiment for the left fake hand as compared to the right hand (as assessed through a standard questionnaire). After recovery from personal neglect for the left arm (second session), the results of the left and right rubber hand illusion experiments were comparable, with no modulation of hand ownership. We argue that personal neglect may consist not only in an inattentional disorder, but also in a deficit of multisensory body representation characterized by a high sensitivity to experimental manipulations of subjective aspects of body ownership.     

Is ‘object-centred neglect’ a homogeneous entity?

The nature of object-centred (allocentric) neglect and the possibility of dissociating it from egocentric (subject-centred) forms of neglect are controversial. Originally, allocentric neglect was described by  and  in patients who reproduced all the elements of a multi-object scene, but left unfinished the left side of one or more of them. More recently, however, Karnath, Mandler, and Clavagnier (2011) have claimed that the severity of allocentric neglect worsens when a complex ‘object’ shifts from an ipsilesional to a contralesional egocentric position. On the basis of these and of other clinical data, showing that allocentric and egocentric neglect are strongly associated, they have questioned the possibility of dissociating these two forms of neglect, suggesting that egocentric and allocentric neglect constitute different manifestations of the same disturbed system. Since these statements were inconsistent with the clinical findings which had prompted the construct of object-centred neglect, we checked in a group of right brain-damaged patients, who had copied the original multi-object scene, if the degree of neglect for the left side of figures varied as a function of their position on the horizontal axis. Furthermore, we reviewed all papers where copies of other multi-object scenes had been reported. Results of both studies failed to confirm the assumption of a relationship between spatial location of the stimulus and severity of object-centred neglect. This discrepancy between our data and those obtained by Karnath et al. (2011) could be due to the characteristics of stimuli and of procedures used to evaluate ‘object-centred’ neglect. If the stimulus is complex and the task requires its thorough exploration, the spatial location of the stimulus will influence the severity of ‘object-centred neglect’. If, on the contrary, the stimulus is simple and can be identified with few eye fixations, the spatial location of the stimulus should not influence the severity of ‘object-centred neglect’. In any case, our data confirm the possibility of dissociating allocentric from egocentric neglect.     

“Where is the sun” for hemi-neglect patients?

Human observers use prior constraints to disambiguate a scene; in particular, light is preferentially seen as coming from above but also slightly from the left. One explanation of this lateral bias could be a cerebral hemispheric difference. The aim of the present study was to determine the preferred light source position for neglect patients. For this purpose, we used the ambiguous shaded “Polo Mint” stimulus, a ring divided into eight equal sectors. All sectors but one were the same shape, convex or concave, as determined by the light source position. Participants had to report the side (left or right) of the odd sector or, in a separate experiment, to report its shape (convex or concave). Eight patients with spatial neglect (left neglect N = 7, right neglect N = 1) after a right or left temporo-parietal or thalamic lesion and 14 control participants ran the experiment. Left neglect patients showed a significantly different light bias from the bias observed for controls and for the right neglect patient (i.e., a reduction of the left bias or a right bias rather than a left bias). We conclude that some disabilities presented by patients with spatial neglect may be due to difficulties processing information that is not present in the visual field or imagined in the representational scene.     

Improving neglect by TMS

Hemispatial neglect refers to the defective ability of patients to explore or act upon the side of space contralateral to the lesion and to attend to stimuli presented in that portion of space. Evidence from animal models suggests that many of the behavioural sequelae associated with visual neglect may result not solely from the size of the lesion, but also from a pathological state of increased inhibition exerted on the damaged hemisphere by the contralesional hemisphere. On the basis of these potential mechanisms underlying neglect, in this review we discuss therapeutic approaches, focusing particularly on recent research using transcranial magnetic stimulation (TMS). This technique, besides representing an ideal tool to investigate visuo-spatial attentive mechanisms in humans, has shown promising beneficial effects that might have an impact on clinical practice.     

Intelligence and the Frontal Lobe: The Organization of Goal-Directed Behavior

Basic to the study of individual differences is the concept of “general intelligence” or Spearman'sg.In this article we suggest thatgis largely a reflection of the control functions of the frontal lobe. A series of experiments investigates a phenomenon we callgoal neglect:disregard of a task requirement even though it has been understood and remembered. Subjectively it is as though the neglected requirement “slips the subject's mind.” Previously described in frontal patients, we show that goal neglect can also be seen in some members of the normal population. In line with conventional distinctions between controlled and automatic processing, eliciting conditions for goal neglect include novelty, weak error feedback, and multiple concurrent task requirements. Under these conditions neglect is linked closely togand extremely common after frontal lesions. Following many other models, we suggest that behavior in any task is structured by a set of action constraints or requirements, derived in part from verbal instructions and specified at multiple levels of abstraction. A frontal process of constraint or requirement activation is fundamental to Spearman'sg.     

Auditory and multisensory aspects of visuospatial neglect

Spatial neglect is a common neurological syndrome in which awareness of contralesional space is disrupted after unilateral (typically right) stroke. Although most research has focused on visual aspects of neglect, there is increasing evidence that neglect can often be multisensory. Here we focus on auditory disturbances that can co-occur with visual neglect. Patients selected for showing visual neglect often also show deficits in localization of single sounds; and also in the detection or identification of contralesional sounds, particularly in the presence of an ipsilesional competitor. Moreover, auditory and visual aspects of neglect often correlate in their severity across patients. These results are considered in relation to recent neuroimaging findings in the normal brain, showing that the brain regions typically damaged in neglect patients might contain multimodal representations of space.     

Goal neglect and knowledge chunking in the construction of novel behaviour

Task complexity is critical in cognitive efficiency and fluid intelligence. To examine functional limits in task complexity, we examine the phenomenon of goal neglect, where participants with low fluid intelligence fail to follow task rules that they otherwise understand. Though neglect is known to increase with task complexity, here we show that – in contrast to previous accounts – the critical factor is not the total complexity of all task rules. Instead, when the space of task requirements can be divided into separate sub-parts, neglect is controlled by the complexity of each component part. The data also show that neglect develops and stabilizes over the first few performance trials, i.e. as instructions are first used to generate behaviour. In all complex behaviour, a critical process is combination of task events with retrieved task requirements to create focused attentional episodes dealing with each decision in turn. In large part, we suggest, fluid intelligence may reflect this process of converting complex requirements into effective attentional episodes.     

When knowledge is not enough: the phenomenon of goal neglect in preschool children

We argue that the concept of goal neglect can be fruitfully applied to understand children's potential problems in experimental tasks and real-world settings. We describe an assessment of goal neglect developed for administration to preschool children and report data on two measures derived from this task alongside the Dimensional Change Card Sort (DCCS) and an opposite color response inhibition task. The propensity to neglect initial task cues was uniquely linked to response inhibition, whereas neglect of a later cue was uniquely linked to the DCCS. Additional evidence suggests that recovery from neglect can occur and shows that goal neglect varies with the cognitive transparency of the signifying cue. Data demonstrate the importance of, and place constraints on, current theories of information regulation and foreground the notion of graded representations in working memory and executive functioning.     

Extra‐powerful on the visuo‐perceptual space,but variable on the number space: Different effects of optokinetic stimulation in neglect patients

We studied the effects of optokinetic stimulation (OKS; leftward, rightward, control) on the visuo‐perceptual and number space, in the same sample, during line bisection and mental number interval bisection tasks. To this end, we tested six patients with right‐hemisphere damage and neglect, six patients with right‐hemisphere damage but without neglect, and six neurologically healthy participants. In patients with neglect, we found a strong effect of leftward OKS on line bisection, but not on mental number interval bisection. We suggest that OKS influences the number space only under specific conditions.     

Mnemic neglect: Selective amnesia of one’s faults

The mnemic neglect model predicts and accounts for selective memory for social feedback as a function of various feedback properties. At the heart of the model is the mnemic neglect effect (MNE), defined as inferior recall for self-threatening feedback compared to other kinds of feedback. The effect emerges both in mundane realism and minimal feedback settings. The effect is presumed to occur in the service of self-protection motivation. Mnemic neglect is pronounced when the feedback poses high levels of self-threat (i.e., can detect accurately one’s weakness), but is lost when self-threat is averted via a self-affirmation manipulation. Mnemic neglect is caused by self-threatening feedback being processed shallowly and in ways that separate it from stored (positive) self-knowledge. The emergence of mnemic neglect is qualified by situational moderators (extent to which one considers their self-conceptions modifiable, receives feedback from a close source, or is primed with improvement-related constructs) and individual differences moderators (anxiety, dysphoria, or defensive pessimism). Finally, the MNE is present in recall, but absent in recognition. Output interference cannot explain this disparity in results, but an inhibitory repression account (e.g., experiential avoidance) can: Repressors show enhanced mnemic neglect. The findings advance research on memory, motivation, and the self.     

Representational neglect for words as revealed by bisection tasks

In the present study, we showed that a representational disorder for words can dissociate from both representational neglect for objects and neglect dyslexia. This study involved 14 brain-damaged patients with left unilateral spatial neglect and a group of normal subjects. Patients were divided into four groups based on presence of left neglect dyslexia and representational neglect for non-verbal material, as evaluated by the Clock Drawing test. The patients were presented with bisection tasks for words and lines. The word bisection tasks (with words of five and seven letters) comprised the following: (1) representational bisection: the experimenter pronounced a word and then asked the patient to name the letter in the middle position; (2) visual bisection: same as (1) with stimuli presented visually; and (3) motor bisection: the patient was asked to cross out the letter in the middle position. The standard line bisection task was presented using lines of different length. Consistent with the literature, long lines were bisected to the right and short lines, rendered comparable in length to the words of the word bisection test, deviated to the left (crossover effect). Both patients and controls showed the same leftward bias on words in the visual and motor bisection conditions. A significant difference emerged between the groups only in the case of the representational bisection task, whereas the group exhibiting neglect dyslexia associated with representational neglect for objects showed a significant rightward bias, while the other three patient groups and the controls showed a leftward bisection bias. Neither the presence of neglect alone nor the presence of visual neglect dyslexia was sufficient to produce a specific disorder in mental imagery. These results demonstrate a specific representational neglect for words independent of both representational neglect and neglect dyslexia.     

Non-lateralised deficits of drawing production in hemispatial neglect

Spatially lateralised deficits that typically define the hemispatial neglect syndrome have been shown to co-occur with other non-lateralised deficits of attention, memory, and drawing. However even a simple graphic task involves multiple planning components, including the specification of drawing start position and drawing direction. In order to investigate the influence of these factors in neglect we presented patients with a circle-copying task, and specified the drawing start point. The ability to draw from the instructed location was strongly related to tests that measure constructional abilities, but not related to start point laterality. In contrast, the direction in which patients drew the circle was affected by start point laterality: patients with neglect were less likely to draw in a typical direction when the cue was on the affected side of space and this was strongly related to severity of the neglect. Patients with neglect consistently produced circles that were smaller than the model; however, the scaling was not affected by the laterality of the start point, nor was the proportion of drawings correctly started at the cue. These findings demonstrate the complex relationship between neglect and even the simplest test for the syndrome.     

Crossover by Line Length and Spatial Location

It is well known that line length has a systematic influence on line bisection error in neglect. Most patients with neglect misbisect long lines on the same side of true center as their brain lesion but then cross over on short lines, misbisecting them on the opposite side (i.e., crossover by line length). What is less recognized is that the spatial location of lines relative to the viewer can similarly induce a crossover effect when one considers line bisection error scores that have been averaged across individual line lengths. Patients with right hemisphere injury and neglect classically make averaged line bisection errors that fall right of true center on lines located either at midline or to the left of the viewer; however, we observed that the averaged line bisection error can fall left of true center when lines are located to the right of the viewer (i.e., crossover by spatial location). We hypothesized that crossover by both line length and spatial location stem from systematic errors in magnitude estimation, i.e., perceived line length. We tested predictions based on this hypothesis by examining how the crossover effect by line length is altered by the spatial location of lines along a horizontal axis relative to the viewer. Participants included patients with unilateral lesions of the right and left cerebral hemispheres and age-appropriate normal subjects. All groups demonstrated a crossover effect by line length at the midline location but the effect was altered by placing lines to the right and left of the viewer. In particular, patients with right hemisphere injury and neglect crossed-over across a broader range of line lengths when the lines were located to the right of the viewer rather than at either midline or left of the viewer. It is proposed that mental representations of stimulus magnitude are altered in neglect, in addition to mental representations of space, and that traditional accounts of neglect can be enhanced by including the psychophysical concept of magnitude estimation.