Behavioural and functional changes in neglect after multisensory stimulation.

The present cohort study investigated whether systematic multisensory audio-visual stimulation might improve clinical signs of neglect. To this aim, patients with neglect (n = 7) and patients with neglect associated with hemianopia (n = 12) were exposed to a course of audio-visual stimulation with spatially and temporally coincident audio-visual pairs of stimuli for 10 daily training sessions (4 h of training per day), over two weeks. Performance on neuropsychological tests assessing neglect was measured before training, immediately after the training and months after the training at a follow-up session. The results showed significant post-training improvements in clinical signs of neglect, which were stable at the follow-up. These findings suggest that intensive and prolonged multisensory audio-visual stimulation affects orientation towards the neglected hemifield, therefore inducing long-term improvements in visual exploration and neglect symptoms in both patients with neglect and patients with neglect associated with hemianopia. Previous evidence from hemianopic patients suggests that these post-training effects might be mediated by activity in spared subcortical structures, such as the superior colliculus, which are relevant to multisensory integrative processing and spatial orientation.

Computer-Based Cognitive Rehabilitation in Patients with Visuospatial Neglect or Homonymous Hemianopia after Stroke.

OBJECTIVES: The purpose of this pilot study was to investigate the feasibility and effects of computer-based cognitive rehabilitation (CBCR) in patients with symptoms of visuospatial neglect or homonymous hemianopia in the subacute phase following stroke. METHOD: A randomized, controlled, unblinded cross-over design was completed with early versus late CBCR including 7 patients in the early intervention group (EI) and 7 patients in the late intervention group (LI). EI received CBCR training immediately after inclusion (m = 19 days after stroke onset) for 3 weeks and LI waited for 3 weeks after inclusion before receiving CBCR training for 3 weeks (m = 44 days after stroke onset). RESULTS: CBCR improved visuospatial symptoms after stroke significantly when administered early in the subacute phase after stroke. The same significant effect was not found when CBCR was administered later in the rehabilitation. The difference in the development of the EI and LI groups during the first 3 weeks was not significant, which could be due to a lack of statistical power. CBCR did not impact mental well-being negatively in any of the groups. In the LI group, the anticipation of CBCR seemed to have a positive impact of mental well-being. CONCLUSION: CBCR is feasible and has a positive effect on symptoms in patients with visuospatial symptoms in the subacute phase after stroke. The study was small and confirmation in larger samples with blinded outcome assessors is needed.

Homonymous Hemianopia in Children and Adolescents: An MRI Study.

AIM: Diagnosing homonymous hemianopia (HH) in children can be difficult due to inability to comply with perimetry. Therefore, HH can often only be suspected by magnetic resonance imaging (MRI) showing lesions to the retrochiasmatic visual pathways. The aim of our retrospective observational cross-sectional study was to improve the radiologic detection of HH. METHODS: MRIs of 21 subjects (5-17 years old) with ophthalmologically confirmed HH (14 complete, 7 incomplete hemianopias) were analyzed. In addition, we asked four questions looking at everyday problems possibly related to the HH. The questions asked for (1) problems in avoiding objects/people, (2) bumping into objects/people, (3) difficulties in judging stairs, and (4) difficulties in grasping objects. RESULTS: We found neuroanatomical correlates of the HH in all 21 participants, with the optic radiation being involved in almost all participants (20/21). Everyday problems possibly related to the HH were reported for all nine patients with postneonatally acquired complete hemianopias. In contrast, no such problems were reported for seven patients with incomplete HH (7/7) and for 3/5 patients with complete hemianopias due to pre-, peri- or neonatally acquired brain lesions. INTERPRETATION: A dedicated radiologic analysis of the retrochiasmatic optic pathway should routinely be performed in children with brain lesions to identify children with HH. Early onset and incomplete HH are predictors for successful compensation.

Difficulties in Daily Life Reported by Patients With Homonymous Visual Field Defects.

BACKGROUND: Homonymous visual field defects (HVFD) are common after postchiasmatic acquired brain injury and may have a significant impact on independent living and participation in society. Vision-related difficulties experienced in daily life are usually assessed using questionnaires. The current study 1) links the content of 3 of these questionnaires to the International Classification of Functioning, Disability and Health (ICF) and 2) provides analyses of vision-related difficulties reported by patients with HVFD and minimal comorbidities. METHODS: Fifty-four patients with homonymous hemianopia or quadrantanopia were asked about difficulties experienced in daily life because of their HVFD. This was performed during a structured interview including 3 standardized questionnaires: National Eye Institute Visual Functioning Questionnaire, Independent Mobility Questionnaire, and Cerebral Visual Disorders Questionnaire. The reported difficulties were linked to the ICF according to the ICF linking rules. Main outcome measures were presence or absence of experienced difficulties. RESULTS: The ICF linking procedure resulted in a classification table that can be used in future studies of vision-related difficulties. Besides well-known difficulties related to reading, orientation, and mobility, a high proportion of patients with HVFD reported problems that previously have not been documented in the literature, such as impaired light sensitivity, color vision, and perception of depth. CONCLUSIONS: A systematic inventory of difficulties experienced in daily life by patients with HVFD was performed using the ICF. These findings have implications for future study, assessment and rehabilitation of patients with HVFD.

Isoluminant coloured stimuli are undetectable in blindsight even when they move.

Moving stimuli are the most effective of all in eliciting blindsight. The detection of static luminance-matched coloured stimuli is negligible or even impossible in blindsight. However, moving coloured stimuli on an achromatic background have not been tested. We therefore tested two blindsighted hemianopes, one of them highly experienced and the other much less so, to determine whether they could perform what should be one of the simplest of all motion tasks: detecting when an array of coloured stimuli moves. On each trial, they were presented in the hemianopic field with an array of spots, all red or green or blue or achromatic, in a circular window and on a white surround. The spots moved coherently in the first or second of two short intervals. The subject had to indicate the interval in which the motion had occurred. The luminance of the spots was varied across different blocks of trials, but the background luminance remained the same throughout. For each colour, there was a ratio of luminance between the spots and the white surround at which performance was not significantly better than chance, although at other ratios, performance was good to excellent, with the exception of blue spots in one subject. We conclude that detecting global coherent motion in blindsight is impossible when it is based on chromatic contrast alone.

Impaired texture segregation but spared contour integration following damage to right posterior parietal cortex.

We examined the relations between texture segregation and contour integration in patients with deficits in spatial attention leading to left or right hemisphere extinction. Patients and control participants were presented with texture and contour stimuli consisting of oriented elements. We induced regularity in the stimuli by manipulating the element orientations resulting in an implicit texture border or explicit contour. Participants had to discriminate curved from straight shapes without making eye movements, while the stimulus presentation time was varied using a QUEST procedure. The results showed that only patients with right hemisphere extinction had a spatial bias, needing a longer presentation time to determine the shape of the border or contour on the contralesional side, especially for borders defined by texture. These results indicate that texture segregation is modulated by attention-related brain areas in the right posterior parietal cortex.

Pathways involved in human conscious vision contribute to obstacle-avoidance behaviour.

Human patients with visual field defects following damage to their primary visual cortex (V1) will often misperceive the midpoint of a horizontal line. They tend to shift the midpoint away from the real position towards their blind field. In patients with unilateral neglect, where midpoint shifts can also be observed, these perceptual errors do not lead to errors in an obstacle-avoidance task, which also requires the ability to find the midpoint between two obstacles. This dissociation in neglect patients was taken as evidence that obstacle-avoidance performance is guided by visual information from the dorsal visual stream. Recently it was shown that a patient with hemianopia could avoid an obstacle presented in his blind field. This suggests that obstacle-avoidance behaviour can be guided by subconscious vision alone involving a direct route from extrageniculate structures in the brain to dorsal stream areas. To investigate whether obstacle avoidance relies only on this subconscious route or also uses information from pathways involved in conscious vision, we examined the effect of the hemianopic shift on obstacle-avoidance behaviour. This shift is found in tasks where a conscious visual judgement is required and presumably arises in pathways underlying conscious vision (V1 and ventral stream areas). We compared the performance of six patients with left hemianopia with the performance of six patients with right hemianopia. We found a clear bias in both groups, which also affected obstacle-avoidance performance. It is thus concluded that obstacle avoidance does not bypass the system for conscious vision completely.

Are hemianopic monkeys and a human hemianope aware of visual events in the blind field?

In three hemianopic monkeys and one normal monkey who subsequently became hemianopic and in one human hemianope we measured reaction times to touch the remembered position of a brief visual target presented in the normal hemifield or in the blind hemifield, or on the blank trials where no visual target occurred and the correct response was to touch a separate and permanently outlined part of the display. This is the same procedure as first used to demonstrate blindsight in these hemianopic monkeys. In the present experiment physically salient high-contrast (0.95) grating stimuli, which we have previously shown are easily detected and localized in the blind field, were used, and the monkeys' reaction times were also measured. With rare exceptions the monkeys indicated that the visual targets in the blind field were blanks, but their otherwise identical motor responses to targets and blanks had significantly different latencies, which were longer for real targets than for blanks. The results indicate that when the monkeys detect that the stimulus has occurred but do not perceive it as a light, or are just guessing, reaction times are longer. Even when the target in the blind field was moving, it was categorized as a blank. In the human hemianope both high- and low-contrast stimuli were used, and the subject had to indicate whether he had been 'aware' or 'unaware' of the target, after making the reaching response. The latencies when he was correct and aware were significantly shorter than when he was unaware and 'just guessing'. However, he was also significantly faster to respond correctly to the blind-field target when he was unaware and correct than when he was unaware and incorrect, a difference reflected in his percentage correct scores even when totally unaware. Collectively, the results support the notion that the hemianopic monkeys, like the human hemianope, know that something has happened in the blind field as long as the stimuli are physically salient even though the stimuli are categorized as blanks, presumably because, like the human hemianope, there was no phenomenal visual percept.

"Real-time" obstacle avoidance in the absence of primary visual cortex.

When we reach toward objects, we easily avoid potential obstacles located in the workspace. Previous studies suggest that obstacle avoidance relies on mechanisms in the dorsal visual stream in the posterior parietal cortex. One fundamental question that remains unanswered is where the visual inputs to these dorsal-stream mechanisms are coming from. Here, we provide compelling evidence that these mechanisms can operate in "real-time" without direct input from primary visual cortex (V1). In our first experiment, we used a reaching task to demonstrate that an individual with a dense left visual field hemianopia after damage to V1 remained strikingly sensitive to the position of unseen static obstacles placed in his blind field. Importantly, in a second experiment, we showed that his sensitivity to the same obstacles in his blind field was abolished when a short 2-s delay (without vision) was introduced before reach onset. These findings have far-reaching implications, not only for our understanding of the time constraints under which different visual pathways operate, but also in relation to how these seemingly "primitive" subcortical visual pathways can control complex everyday behavior without recourse to conscious vision.

Are vision-specific quality of life questionnaires important in assessing rehabilitation for patients with hemianopia post stroke?

OBJECTIVE: To explore the relationship between disability and functional measures with vision-specific quality of life (QoL) measures for people with hemianopia and stroke. METHOD: The Behavioral Inattention Test (BIT) and the Mayo-Portland Adaptability Inventory (MPAI) were compared with scores on 2 vision-specific QoL measures, the National Eye Institute Visual Function Questionnaire (NEI VFQ-25) and Veteran Low Vision Visual Function Questionnaire (VA LV VFQ-48). SETTING: Rehabilitation hospitals in Adelaide, South Australia. PARTICIPANTS: Stroke patients (n = 24) with homonymous hemianopia. RESULTS: Most of the BIT and MPAI scores were significantly associated with the NEI VFQ-25 and VA LV VFQ-48 scores. Behavioral test scores of the BIT and the MPAI total score correlated with more aspects of the QoL measures than the other components of the BIT and the MPAI. CONCLUSION: BIT and MPAI measure constructs associated with QoL for people with hemianopia following stroke. Vision-specific QoL questionnaires can complement the functional instruments by identifying the domains of difficulty, based on the instrument's subscale, that can guide rehabilitation therapists to address the person's deficit.

Vision-related quality of life in first stroke patients with homonymous visual field defects.

BACKGROUND: To evaluate vision-related and health-related quality of life (VRQoL, HRQoL) in first stroke patients with homonymous visual field defects (VFD) with respect to the extent of the lesion. Since VFD occur in approximately 10% of stroke patients the main purpose of the study was to investigate the additional impact of VFD in stroke patients hypothesizing that VFD causes diminished VRQoL. METHODS: In 177 first stroke patients with persisting VFD 2.5 years after posterior-parietal lesions VRQoL was assessed by the National-Eye-Institute-Visual-Functioning-Questionnaire (NEI-VFQ) and HRQoL by the Medical-Outcome-Study Short-Form-36 Health-Survey (SF-36). Questionnaire results of VFD-patients were compared with age- and sex-matched healthy controls and with general non-selected stroke samples as published elsewhere. VFD-type and visual acuity were partially correlated with questionnaire results. RESULTS: Compared to healthy controls VFD-patients had lower NEI-VFQ scores except ocular pain (Z-range -11.34 to -3.35) and lower SF-36 scores except emotional role limitations (Z-range -7.21 to -3.34). VFD-patients were less impaired in SF-36 scores than general stroke patients one month post lesion (6/8 subscales) but had lower SF-36 scores compared to stroke patients six months post lesion (5/8 subscales). Visual acuity significantly correlated with NEI-VFQ scores (r-range 0.27 to 0.48) and VFD-type with SF-36 mental subscales (r-range -0.26 to -0.36). CONCLUSIONS: VFD-patients showed substantial reductions of VRQoL and HRQoL compared to healthy normals, but better HRQoL compared to stroke patients one month post lesion. VFD-patients (although their lesion age was four times higher) had significantly lower HRQoL than a general stroke population at six months post-stroke. This indicates that the stroke-related subjective level of HRQoL impairment is significantly exacerbated by VFD. While VRQoL was primarily influenced by visual acuity, mental components of HRQoL were influenced by VFD-type with larger VFD being associated with more distress.

[Impairments of vision- and health-related quality of life in stroke patients with homonymous visual field defects depend on severity of visual function loss]. / Beeinträchtigung der seh- und gesundheitsbezogenen Lebensqualität bei Schlaganfallpatienten mit homonymen Gesichtsfelddefekten in Abhängigkeit von der Schwere des visuellen Funktionsverlustes.

BACKGROUND AND PURPOSE: Little is known about whether and to what extent health- and vision-related quality of life in stroke patients with visual field defects is influenced by the severity of visual function loss and which quality of life is achieved compared to healthy control persons. PATIENTS/MATERIALS AND METHODS: Results of the National Eye Institute-Visual Functioning Questionnaire (NEI-VFQ) and the Medical Outcome Study Short-Form 36 Health Survey (SF-36) of 177 first stroke patients with visual field defects were compared with scores of age- and sex-matched healthy reference persons. The influence of visual field loss, perimetric data, reduced visual acuity and demographic variables on NEI-VFQ and SF-36 scores were estimated by analyses of variance. RESULTS: First stroke patients showed worse results in 11/12 NEI-VFQ and in 6/8 SF-36 subscales when compared to healthy controls. The factor "intact central visual field" influenced 9/12 NEI-VFQ subscales (F-range 3.16 - 14.11; all p < 0.05), but only one SF-36 scale (F = 3.15; p < 0.05). Patients with larger intact visual fields, shorter reaction times in the visual field test and better visual acuity reached higher NEI-VFQ and SF-36 scores. Male patients reported worse scores for SF-36 subscale General Health Perceptions than female patients (F = 8.61; p = 0.004), but no differences in vision-related quality of life due to the factor gender could be detected. CONCLUSIONS: Patients with visual field defects showed considerable reductions in vision- and health-related quality of life compared to healthy control persons. These were mainly influenced by variables of visual functioning such as size of intact visual field, reaction times or visual acuity. The size of the intact central visual field influenced vision-related quality of life rather than health-related quality of life.

Neuropsychology of acute stroke.

Neuropsychology includes both the psychiatric manifestations of neurological illness (primary brain-based disorders) and neurobiology of "idiopathic" psychiatric disorders. Neurological primary brain disorders provoke broad spectrum of brain pathophysiology that cause deficit sin human behaviour, and the magnitude of neurobehavioral-related problems is a world wide health concern. Speech disorders of aphasic type, unilateral neglect, anosognosia (deficit disorders), delirium and mood disorders (productive disorders) in urgent neurology, first of all in acute phase of stroke are more frequent disorders then it verified in routine exam, not only in the developed and large neurological departments. Aphasia is common consequence of left hemispheric lesion and most common neuropsychological consequence of stroke, with prevalence of one third of all stroke patients in acute phase although exist reports on greater frequency. Unilateral neglect is a disorder that mostly effects the patient after the lesion of the right hemisphere, mostly caused by a cerebrovascular insult (infarct or haemorrhage affecting a large area - up to two thirds of the right hemisphere), and in general the left-side neglect is the most widespread neuropsychological deficit after the lesion of the right cerebral hemisphere. Reports on the incidence of visual neglect vary and they range from 13 to 85%. Anosognosia is on the second place as neuropsychological syndrome of stroke in right hemisphere, characterized by the denial of the motor, visual or cognitive deficit. This syndrome, defined as denial of hemiparesis or hemianopsia, is a common disorder verified in 17-28% of all patents with acute brain stoke. There are different reports on frequency of delirium in acute stroke, from 24 to 48%, and it is more frequent in hemorrhagic then ischemic stoke. Post stroke depression (PSD) is one of the more frequent consequences on the stroke, and the prevalence of PSD has ranged from 5 to 63% of patients in several cross-sectional studies, peaking three to six months after a stroke.

Dissociations between perception and awareness in hemianopia.

The most common visual defect to follow a lesion of the retrochiasmal pathways is homonymous hemianopia (HH), whereby patients are blind to the contralesional visual field of each eye. Homonymous hemianopia has been studied in terms of its deleterious consequences on perceptual, cognitive and motor tasks as well as because it represents an interesting model of vision loss after a unilateral lesion of the occipital lobe. From a behavioral perspective, in addition to exhibiting a severe deficit in their contralesional visual field, HH patients can also exhibit dissociations between perception and awareness. Firstly, HH patients suffering from anosognosia may be unaware of their visual field defect. Secondly, HH patients can present with unconscious visual abilities in the blind hemifield, a phenomenon referred to as blindsight. Thirdly, recent reports demonstrate that HH patients can suffer from a subtle deficit in their ipsilesional visual field that they are unaware of, a condition called sightblindness (i.e. the reverse case of 'blindsight'). Finally, HH patients may also exhibit visual hallucinations in their blind field; however, such patients are not systematically aware that their perceptions are unreal. In this review, we provide an overview of the visual-field losses in HH patients after a left or right unilateral occipital lesion. Furthermore, we explore the implications of these four phenomena for models of visual processing and rehabilitation of visual field defects in HH patients. Finally, in contrast to the traditional view that HH is solely a visual-field defect, we discuss why this deficit is an interesting model for studying the dissociation between perception and awareness.

Audio-visual stimulation improves oculomotor patterns in patients with hemianopia.

Patients with visual field disorders often exhibit impairments in visual exploration and a typical defective oculomotor scanning behaviour. Recent evidence [Bolognini, N., Rasi, F., Coccia, M., & Làdavas, E. (2005b). Visual search improvement in hemianopic patients after audio-visual stimulation. Brain, 128, 2830-2842] suggests that systematic audio-visual stimulation of the blind hemifield can improve accuracy and search times in visual exploration, probably due to the stimulation of Superior Colliculus (SC), an important multisensory structure involved in both the initiation and execution of saccades. The aim of the present study is to verify this hypothesis by studying the effects of multisensory training on oculomotor scanning behaviour. Oculomotor responses during a visual search task and a reading task were studied before and after visual (control) or audio-visual (experimental) training, in a group of 12 patients with chronic visual field defects and 12 controls subjects. Eye movements were recorded using an infra-red technique which measured a range of spatial and temporal variables. Prior to treatment, patients' performance was significantly different from that of controls in relation to fixations and saccade parameters; after Audio-Visual Training, all patients reported an improvement in ocular exploration characterized by fewer fixations and refixations, quicker and larger saccades, and reduced scanpath length. Overall, these improvements led to a reduction of total exploration time. Similarly, reading parameters were significantly affected by the training, with respect to specific impairments observed in both left- and right-hemianopia readers. Our findings provide evidence that Audio-Visual Training, by stimulating the SC, may induce a more organized pattern of visual exploration due to an implementation of efficient oculomotor strategies. Interestingly, the improvement was found to be stable at a 1 year follow-up control session, indicating a long-term persistence of treatment effects on the oculomotor system.

Impairments of Gestalt perception in the intact hemifield of hemianopic patients are reflected in gamma-band EEG activity.

Gamma-band responses (GBRs) are associated with Gestalt perception processes. In the present EEG study, we investigated the effects of perceptual grouping on the visual GBR in the perimetrically intact visual field of patients with homonymous hemianopia and compared them to healthy participants. All observers were presented either random arrays of Gabor elements or arrays with an embedded circular arrangement. For the hemianopic patients, the circle was presented in their intact hemifield only. For controls, the hemifield for the circle presentation was counterbalanced across subjects. The participants were instructed to detect the circle by pressing a corresponding button. A wavelet transform based on Morlet wavelets was employed for the calculation of oscillatory GBRs. The early evoked GBR exhibited a larger amplitude and shorter latency for the healthy group compared to hemianopic patients and was associated with behavioral measures. The late total GBR between 200 and 400ms after stimulus onset was significantly increased for Gestalt-like patterns in healthy participants. This effect was not manifested in patients. The present findings indicate deficits in the early and late visual processing of Gestalt patterns even in the intact hemifield of hemianopic patients compared to healthy participants.

Neural correlates of hemianopic completion across the vertical meridian.

Hemianopic completion refers to the perceptual completion of figures located across the vertical meridian in the context of hemianopia, such that one half of the figure falls within the blind hemifield. It can occur whether the figure is itself complete (veridical completion) or incomplete (paracompletion). Psychophysical evidence suggests that this phenomenon may be a constructive one, and may share features with completion phenomena in normal vision. The neural structures mediating hemianopic completion are unknown. Here we studied the neural activity evoked by hemianopic completion using event-related fMRI in an individual (POV) with a large right visual field homonymous hemianopic scotoma due to left occipital damage. Either a large achromatic circular contour straddling the vertical meridian or a semicircular contour within the left hemifield just crossing the vertical meridian was presented to POV on each trial. POV indicated by button press whether he perceived a semicircular contour, a patchy circular contour or a complete circular contour. On trials where he reported perceiving a complete circular contour despite being presented with a semicircular contour (paracompletion), activity was increased in a region of ipsilateral extrastriate cortex (contralateral to the lesion, ipsilateral to the illusory edge of the circle). These results are discussed in the context of illusory contour completion in healthy subjects and more generally in the recovery of function after brain damage.

Cross-modal localization in hemianopia: new insights on multisensory integration.

The superior colliculus (SC) has been implicated in the mediation of residual visual function in hemianopic patients, and has been shown to be capable of using multiple sensory cues to facilitate its localization functions. The aim of the present study was to examine the possibility that the SC could effect covert visual processes, via multisensory integration of auditory and visual stimuli in patients with visual field loss. To this aim hard-to-localize auditory targets were presented alone (unimodal condition) or with a visual stimulus (cross-modal condition) in either hemifield and at various spatial (0 degree, 16 degrees, 32 degrees) and temporal (0 ms, 500 ms) disparities. The results showed substantial field-specific differences. As expected, a visual stimulus in the intact hemifield induced a strong visual bias in auditory localization independent of the spatial disparities, and did so even when the two stimuli were temporally offset. In these spatially disparate conditions, the localization accuracy was markedly reduced. In the blind hemifield, however, the visual stimulus affected auditory localization only when it was coincident with that target in both space and time. In this circumstance auditory localization performance was markedly enhanced. This result strongly suggests that covert visual processes remain active in hemianopia, though they differ from those in the normal hemifield. A likely explanation of these differences is that enhancement and visual bias depend on different neural pathways: with the former dependent on circuits involving the superior colliculus, a structure involved in the integration of cues from multiple senses to facilitate orientation/localization; and the latter dependent on geniculo-striate circuits that facilitate more detailed analyses of the visual scene. Overall the present results not only enhance our understanding of the impact of covert visual processes in hemianopic patients, but also enhance our knowledge of how different brain regions areas contribute to processing cross-modal information.

Impaired visual processing of contralesional stimuli in neglect patients: a visual-evoked potential study.

Transient visual-evoked potentials (VEPs) were recorded in 11 patients with right brain damage and spatial neglect. High-resolution EEG was recorded using focal stimuli located in the four visual quadrants. VEPs to left stimuli, i.e. located in the neglected side, were compared to VEPs to right stimuli. Results showed that bottom-up processing of a visual stimulus located in the neglected hemifield was intact up to approximately 130 ms from stimulus onset. Hemispheric differences were not significant for either C1 or P1 components representing the activity of striate and extrastriate areas, respectively. In contrast, visual processing in more dorsal areas adjacent to the superior parietal lobe was changed from normal. We failed to record the N1a component for left visual field stimuli expected in the 130-160 ms time range. Furthermore, the N1p (140-180 ms) and P2 (180-220) components were delayed and/or reduced in amplitude for stimuli located on the neglected side. The source of the N1a was previously localized in the intraparietal sulcus in the dorsal occipital cortex; N1p may represent a reactivation of area V3A and P2 reactivation of occipital visual areas including V1 due to top-down feedbacks. Six patients with left brain damage (LBD) and no neglect and 21 healthy subjects were also tested in the same experimental conditions used for patients with neglect. In LBD patients, all components evoked by contralesional stimuli were comparable to ipsilesional components. Overall, data allow localizing in time and space the processing deficit specific for patients with neglect. The first takes place around 130 ms in the bottom-up processing at the level of the anatomically intact dorsal parietal areas; the second is located at the level of the reactivation of the striate and extrastriate areas via feedback connections from higher visual areas. The two functional impairments were limited to left-field stimuli.

Vision-related quality of life in patients with complete homonymous hemianopia post stroke.

PURPOSE: The aim is to determine the characteristics of vision-specific quality of life restriction using the National Eye Institute Visual Function Questionnaire (NEI VFQ-25) and Veterans Affairs Low Vision Visual Function Questionnaire (VA LV VFQ-48) in patients with complete homonymous hemianopia (HH) post stroke. METHOD: Prospective cohort study of patients with complete HH compared to age- and gender-matched subjects with normal visual fields. RESULTS: In the NEI VFQ-25, scores on five subscales were significantly reduced after multiple logistic regression accounting for vision and comorbidities. The five subscales are vision-specific social functioning, vision-specific mental health, vision-specific dependency, driving, and peripheral vision. In the VA LV VFQ-48 postregression analysis, mobility is the only domain that is significantly affected in the people with HH. CONCLUSION: Identification of the significant areas of visual difficulties and their effects on quality of life is important as it can help better address the patients' rehabilitation needs. The current study identifies the need for orientation and mobility training as well as independent living rehabilitation in patients with HH to help address the difficulties in their vision-specific quality of life and maximize their residual vision.