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2.
Stroke ; 55(9): 2325-2339, 2024 Sep.
Article in English | MEDLINE | ID: mdl-39016005

ABSTRACT

BACKGROUND: Visuospatial neglect is a common consequence of stroke and is characterized by impaired attention to contralesional space. Currently, the extent and time course of recovery from neglect are not clearly established. This systematic review and meta-analysis aimed to determine the recovery trajectory of poststroke neglect with standard treatment. METHODS: PsycInfo, Embase, and MEDLINE were searched for articles reporting recovery rates of neglect after stroke. Time since stroke was categorized into early (0-3 months), mid (3-6 months), and late (>6 months) recovery phases. Random-effects models for pooled prevalence were generated for each phase, and potential sources of heterogeneity were explored with metaregressions. Methodological quality of each study was assessed using the Joanna Briggs Institute checklist, with low-quality studies excluded in sensitivity analyses. RESULTS: The search captured 4130 articles including duplicates, and 111 full-text reviews were undertaken. A total of 27 studies reporting data from 839 stroke survivors with neglect were included for review. Meta-analyses indicated a recovery rate of 42% in the early phase, which increased to 53% in the mid-recovery phase. Additional recovery in the late phase was minimal, with an estimated 56% recovery rate. Heterogeneity of studies was high (I2>75%) in all 3 phases of recovery. Estimates were robust to sensitivity analyses. Metaregressions showed significantly greater recovery in studies that included patients with left-hemisphere lesions (ß=0.275, P<0.05, I2=84%). CONCLUSIONS: Most recovery from neglect occurs in the first 3 months, although additional gains can be expected up to 6 months poststroke. While a large proportion of patients recover from neglect, over 40% show persistent symptoms. Further research is needed on effective rehabilitation interventions, particularly focusing on patients most at risk of chronic visuospatial neglect. REGISTRATION: URL: https://www.crd.york.ac.uk/PROSPERO/; Unique identifier: CRD42023388763.


Subject(s)
Perceptual Disorders , Recovery of Function , Stroke , Humans , Perceptual Disorders/etiology , Perceptual Disorders/rehabilitation , Recovery of Function/physiology , Stroke/complications , Stroke/psychology , Stroke Rehabilitation/methods
3.
Invest Ophthalmol Vis Sci ; 65(8): 46, 2024 Jul 01.
Article in English | MEDLINE | ID: mdl-39078731

ABSTRACT

Purpose: The purpose of this study was to investigate gaze-scanning by pedestrians with homonymous hemianopia (HH) when walking on mid-block sidewalks. Methods: Pedestrians with right homonymous hemianopia (RHH), and left homonymous hemianopia (LHH) without and with left spatial neglect (LHSN) walked on city streets wearing a gaze-tracking system. Gaze points were obtained by combining head movement and eye-in-head movement. Mixed-effects regression models were used to compare horizontal gaze scan magnitudes and rates between the side of the hemi-field loss (BlindSide) and the seeing side (SeeingSide), among the three subject groups, and between mid-block walking and street crossing segments. Results: A total of 7021 gaze scans were obtained from 341 minutes of mid-block walking videos by 19 participants (6 with LHH, 7 with RHH, and 6 with LHSN). The average gaze magnitude and scanning rate in mid-block segments were significantly higher towards the BlindSide than the SeeingSide in LHH (magnitude larger by 1.9° (degrees), P = 0.006; scan rate higher by 4.2 scans/minute, P < 0.001) and RHH subjects (magnitude larger by 3.3°, P < 0.001; scan rate higher by 3.2 scans/minute, P = 0.002), but they were not significantly different in LHSN subjects. The scanning rate, in terms of scans/minute (mean, 95% confidence interval [CI]) was significantly lower in LHSN subjects (mean = 6.9, 95% CI = 5.6-8.7) than LHH (mean = 10.2, 95% CI = 8.0-13.1; P = 0.03) and RHH (mean = 11.1, 95% CI = 9.0-13.7; P = 0.007) subjects. Compared to street-crossings, the scan rate during the mid-block segments was lower by 3.5 scans/minute (P < 0.001) and the gaze magnitude was smaller by 3.8° (P < 0.001) over the 3 groups. Conclusions: Evidence of compensatory scanning suggests a proactive, top-down mechanism driving gaze in HH. The presence of spatial neglect (SN) appeared to negatively impact the top-down process.


Subject(s)
Fixation, Ocular , Hemianopsia , Pedestrians , Perceptual Disorders , Visual Fields , Humans , Hemianopsia/physiopathology , Hemianopsia/diagnosis , Male , Female , Aged , Middle Aged , Perceptual Disorders/physiopathology , Perceptual Disorders/etiology , Visual Fields/physiology , Fixation, Ocular/physiology , Walking/physiology , Head Movements/physiology , Eye Movements/physiology , Adult , Aged, 80 and over , Eye-Tracking Technology
4.
Rev Neurol ; 78(12): 327-334, 2024 Jun 16.
Article in Spanish | MEDLINE | ID: mdl-38867681

ABSTRACT

INTRODUCTION: Patients who have suffered a stroke may present with visuospatial neglect (VSN). In clinical practice, different degrees of impairment can be observed among patients with VSN; however, there is no consensus regarding the criteria and tests used to determine them. AIM: This study aims to classify patients with VSH based on their level of impairment and to study their response to computerized cognitive training. PATIENTS AND METHODS: The sample consisted of 34 patients (19 men and 15 women) with a mean age of 47.59 ± 8.39 years. All patients underwent a neuropsychological exploration protocol composed of specific tests that assess visuospatial attention and others to evaluate multiple cognitive domains. All participants underwent computerized cognitive training consisting of 15 one-hour sessions. RESULTS: A cluster analysis was performed that divided the sample into three groups: group 1: mildly affected VSN (n = 17), group 2: moderately affected VSN (n = 11), and group 3: severely affected VSN (n = 6). Statistically significant differences were found in all tests of the visuospatial attention protocol, both in the pre-treatment and post-treatment evaluation. CONCLUSIONS: There are different levels of impairment among patients with VSN, differences that persist after applying computerized cognitive training. These results suggest that the evolution of VSN follows a homogeneous pattern linked to the initial level of impairment. These findings, although preliminary, may be relevant to neurorehabilitation professionals.


TITLE: Variabilidad interindividual en pacientes con heminegligencia visuoespacial: estudio retrospectivo.Introducción. Los pacientes que han sufrido un ictus pueden presentar heminegligencia visuoespacial (HVE). En la práctica clínica es posible observar diferentes grados de afectación entre los pacientes con HVE; sin embargo, no existe consenso respecto a los criterios y pruebas utilizadas para determinarlos. Objetivo. Este estudio tiene como objetivo clasificar a los pacientes que presentan HVE en función de su nivel de afectación y estudiar su respuesta a un entrenamiento cognitivo computarizado. Pacientes y métodos. La muestra estaba formada por 34 pacientes (19 hombres y 15 mujeres) con una edad media de 47,59 ± 8,39 años. A todos los pacientes se les administró un protocolo de exploración neuropsicológico compuesto por pruebas específicas que evalúan la atención visuoespacial y otro para evaluar múltiples dominios cognitivos. Todos los participantes realizaron un entrenamiento cognitivo computarizado consistente en 15 sesiones de una hora de duración. Resultados. Se realizó un análisis de conglomerados que dividió la muestra en tres grupos: grupo 1, HVE con afectación leve (n = 17); grupo 2, HVE con afectación moderada (n = 11); y grupo 3, HVE con afectación grave (n = 6). Se obtuvieron diferencias estadísticamente significativas en todas las pruebas del protocolo de atención visuoespacial, tanto en la evaluación pretratamiento como en la postratamiento. Conclusiones. Existen diferentes niveles de afectación entre los pacientes con HVE, diferencias que se mantienen después de aplicar un entrenamiento cognitivo computarizado. Estos resultados sugieren que la evolución de la HVE sigue un patrón homogéneo vinculado al nivel de afectación inicial. Estos hallazgos, aunque preliminares, pueden ser relevantes para los profesionales de la neurorrehabilitación.


Subject(s)
Perceptual Disorders , Humans , Perceptual Disorders/etiology , Female , Male , Middle Aged , Retrospective Studies , Adult , Neuropsychological Tests , Aged
5.
Neuroscience ; 552: 47-53, 2024 Aug 06.
Article in English | MEDLINE | ID: mdl-38880241

ABSTRACT

Cerebral small vessel disease (CSVD) impairs visuospatial function, and this is one of the most obvious areas of cognitive impairment in CSVD. So, recognizing, monitoring, and treating visuospatial dysfunction are all important to the prognosis of CSVD. This review discussed the anatomical and pathological mechanisms, clinical recognition (scales, imaging, and biomarkers), and treatment of cognitive impairment especially visuospatial dysfunction in CSVD.


Subject(s)
Cerebral Small Vessel Diseases , Humans , Cerebral Small Vessel Diseases/complications , Cerebral Small Vessel Diseases/physiopathology , Cognitive Dysfunction/physiopathology , Cognitive Dysfunction/etiology , Space Perception/physiology , Perceptual Disorders/physiopathology , Perceptual Disorders/etiology , Visual Perception/physiology
6.
Brain Res Bull ; 214: 111003, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38852652

ABSTRACT

An influential model of spatial attention postulates three main attention-orienting mechanisms: disengagement, shifting, and engagement. Early research linked disengagement deficits with superior parietal damage, regardless of hemisphere or presence of spatial neglect. Subsequent studies supported the involvement of more ventral parietal regions, especially in the right hemisphere, and linked spatial neglect to deficient disengagement from ipsilateral cues. However, previous lesion studies faced serious limitations, such as small sample sizes and the lack of brain-injured controls without neglect. Additionally, some studies employed symbolic cues or used long cue-target intervals, which may fail to reveal impaired disengagement. We here used a machine-learning approach to conduct lesion-symptom mapping (LSM) on 89 patients with focal cerebral lesions to the left (LH) or right (RH) cerebral hemisphere. A group of 54 healthy participants served as controls. The paradigm used to uncover disengagement deficits employed non-predictive cues presented in the visual periphery and at short cue-target intervals, targeting exogenous attention. The main factors of interest were group (healthy participants, LH, RH), target position (left, right hemifield) and cue validity (valid, invalid). LSM-analyses were performed on two indices: the validity effect, computed as the absolute difference between reaction times (RTs) following invalid compared to valid cues, and the disengagement deficit, determined by the difference between contralesional and ipsilesional validity effects. While LH patients showed general slowing of RTs to contralesional targets, only RH patients exhibited a disengagement deficit from ipsilesional cues. LSM associated the validity effect with a right lateral frontal cluster, which additionally affected subcortical white matter of the right arcuate fasciculus, the corticothalamic pathway, and the superior longitudinal fasciculus. In contrast, the disengagement deficit was related to damage involving the right temporoparietal junction. Thus, our results support the crucial role of right inferior parietal and posterior temporal regions for attentional disengagement, but also emphasize the importance of lateral frontal regions, for the reorienting of attention.


Subject(s)
Attention , Frontal Lobe , Functional Laterality , Parietal Lobe , Reaction Time , Humans , Male , Female , Middle Aged , Parietal Lobe/physiopathology , Attention/physiology , Aged , Functional Laterality/physiology , Adult , Reaction Time/physiology , Frontal Lobe/physiopathology , Perceptual Disorders/etiology , Perceptual Disorders/physiopathology , Cues , Space Perception/physiology , Brain Injuries/physiopathology
7.
Dev Neuropsychol ; 49(5): 207-224, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38904205

ABSTRACT

In the absence of any complaints in early childhood, preterm children remain more at risk of encountering academic difficulties, but their clinical picture remains not well characterized. We screened visuospatial perception in 70 children born preterm consulting for scholar complaints. Developmental Coordination Disorder (with or without comorbidities) was associated with high prevalence (27%) of impaired perception of spatial relationship. Prematurely born children who obtained no diagnosis of Neuro-Developmental Disorder exhibited a high prevalence (31%) of impaired perception of object magnitude. Regression revealed that low gestational age and fetal growth restriction significantly predicted the magnitude but not the spatial relationship perception.


Subject(s)
Infant, Premature , Space Perception , Humans , Female , Male , Space Perception/physiology , Child , Perceptual Disorders/etiology , Perceptual Disorders/physiopathology , Child, Preschool , Visual Perception/physiology , Infant, Newborn , Cerebral Palsy/physiopathology , Fetal Growth Retardation/physiopathology , Gestational Age
8.
Brain Nerve ; 76(6): 749-754, 2024 Jun.
Article in Japanese | MEDLINE | ID: mdl-38853504

ABSTRACT

Unilateral spatial neglect is the failure of brain-damaged patients to report, respond, or orient to novel or meaningful stimuli presented to the contralateral side of the lesion. This usually involves the right cerebral hemisphere. Neglect presents with no restriction in gaze direction and results in difficulty across various aspects of daily activities, distinguishing it from simple homonymous hemianopia. The basic mechanisms underlying neglect is rightward bias of spatial attention, while non-direction-specific cognitive problems may contribute to clinical expressions of neglect.


Subject(s)
Perceptual Disorders , Humans , Perceptual Disorders/physiopathology , Perceptual Disorders/etiology , Space Perception/physiology , Attention/physiology , Functional Laterality/physiology
9.
Brain Nerve ; 76(6): 755-759, 2024 Jun.
Article in Japanese | MEDLINE | ID: mdl-38853505

ABSTRACT

Unilateral spatial neglect (USN) is a symptom of unilateral brain damage resulting in failure to report sensory phenomena in the contra-lesional space. It is associated with motor impairment as well as sensory deficits. Recent research suggests that USN, may be caused by a disruption in the interhemispheric balance of the visual attention network. Based on this hypothesis, non-invasive brain stimulation (NIBS), such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), is utilized in the rehabilitation of USN patients. Presently, inhibitory stimulation by continuous theta burst stimulation (cTBS) on contra-lesional parietal cortex are believed to be the most promising method. Conversely, compensation by attentional network of the non-lesioned hemisphere plays an important role in the recovery of USN. Recent imaging studies revealed that functional and structural connectivity of attentional networks within a lesioned hemisphere and between lesioned and non-lesioned hemispheres affects spontaneous recovery and effectiveness of rehabilitation approach such as prism adaptation therapy. These findings are useful in elucidating the pathophysiology of USN and predicting functional outcome. Furthermore, we hope that understanding the pathophysiology will enable the development of new rehabilitation strategies and appropriate treatment selection.


Subject(s)
Perceptual Disorders , Transcranial Magnetic Stimulation , Humans , Perceptual Disorders/rehabilitation , Perceptual Disorders/physiopathology , Perceptual Disorders/therapy , Perceptual Disorders/etiology , Transcranial Direct Current Stimulation , Attention/physiology
10.
J Vis ; 24(6): 3, 2024 Jun 03.
Article in English | MEDLINE | ID: mdl-38837169

ABSTRACT

The primary symptom of visual snow syndrome (VSS) is the unremitting perception of small, flickering dots covering the visual field. VSS is a serious but poorly understood condition that can interfere with daily tasks. Several studies have provided qualitative data about the appearance of visual snow, but methods to quantify the symptom are lacking. Here, we developed a task in which participants with VSS adjusted parameters of simulated visual snow on a computer monitor until the simulation matched their internal visual snow. On each trial, participants (n = 31 with VSS) modified the size, density, update speed, and contrast of the simulation. Participants' settings were highly reliable across trials (intraclass correlation coefficients > 0.89), and they reported that the task was effective at stimulating their visual snow. On average, visual snow was very small (less than 2 arcmin in diameter), updated quickly (mean temporal frequency = 18.2 Hz), had low density (mean snow elements vs. background = 2.87%), and had low contrast (average root mean square contrast = 2.56%). Our task provided a quantitative assessment of visual snow percepts, which may help individuals with VSS communicate their experience to others, facilitate assessment of treatment efficacy, and further our understanding of the trajectory of symptoms, as well as the neural origins of VSS.


Subject(s)
Visual Fields , Humans , Adult , Male , Female , Visual Fields/physiology , Young Adult , Photic Stimulation/methods , Middle Aged , Contrast Sensitivity/physiology , Perceptual Disorders/physiopathology , Perceptual Disorders/etiology , Visual Perception/physiology , Computer Simulation , Vision Disorders/physiopathology
11.
Exp Brain Res ; 242(7): 1731-1744, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38819648

ABSTRACT

Dysfunctions in sensory processing are widely described in individuals with autism spectrum disorder (ASD), although little is known about the developmental course and the impact of these difficulties on the learning processes during the preschool and school ages of ASD children. Specifically, as regards the interplay between visual and haptic information in ASD during developmental age, knowledge is very scarce and controversial. In this study, we investigated unimodal (visual and haptic) and cross-modal (visuo-haptic) processing skills aimed at object recognition through a behavioural paradigm already used in children with typical development (TD), with cerebral palsy and with peripheral visual impairments. Thirty-five children with ASD (age range: 5-11 years) and thirty-five age-matched and gender-matched typically developing peers were recruited. The procedure required participants to perform an object-recognition task relying on only the visual modality (black-and-white photographs), only the haptic modality (manipulation of real objects) and visuo-haptic transfer of these two types of information. Results are consistent with the idea that visuo-haptic transfer may be significantly worse in ASD children than in TD peers, leading to significant impairment in multisensory interactions for object recognition facilitation. Furthermore, ASD children tended to show a specific deficit in haptic information processing, while a similar trend of maturation of visual modality between the two groups is reported. This study adds to the current literature by suggesting that ASD differences in multisensory processes also regard visuo-haptic abilities necessary to identify and recognise objects of daily life.


Subject(s)
Autism Spectrum Disorder , Recognition, Psychology , Touch Perception , Humans , Autism Spectrum Disorder/physiopathology , Male , Female , Child , Child, Preschool , Touch Perception/physiology , Recognition, Psychology/physiology , Visual Perception/physiology , Photic Stimulation/methods , Perceptual Disorders/physiopathology , Perceptual Disorders/etiology
12.
Neurocase ; 30(2): 73-76, 2024 04.
Article in English | MEDLINE | ID: mdl-38771586

ABSTRACT

Feeling of body ownership is a complex process with different brain mechanisms involved in integrating the varied and multiple representations of the body . The ability to discriminate between one's own and others' body parts can be lost after brain damage. We report a unique case study of a patient with head injury who experienced a phenomenon where he felt that his head was positioned with another person standing next to him. We describe this as a form of pathological embodiment and call it the "head mislocalization" phenomenon. We report his clinical findings and using the methods of lesion mapping and lesion network mapping postulate the neural mechanisms for this symptom.


Subject(s)
Brain Injuries, Traumatic , Humans , Male , Brain Injuries, Traumatic/complications , Brain Injuries, Traumatic/pathology , Body Image , Perceptual Disorders/etiology , Perceptual Disorders/physiopathology , Adult
13.
Arch Phys Med Rehabil ; 105(8): 1449-1457, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38750715

ABSTRACT

OBJECTIVE: To investigate the effects of a stimulus response task using virtual reality (VR) for unilateral spatial neglect (USN). DESIGN: Double-blind randomized controlled trial. SETTING: Acute phase hospital where stroke patients are hospitalized. PARTICIPANTS: The participants were 42 patients (N=42) with right-hemisphere cerebral damage who had been experiencing USN in their daily lives. They were randomly assigned to 3 groups: a stimulus response task with a background shift (SR+BS group), a stimulus response task without a background shift (SR group), and an object gazing task (control group). INTERVENTIONS: The stimulus response task was to search for balloons that suddenly appeared on the VR screen. A background shift was added to highlight the search in the neglected space. The control task was to maintain a controlled gaze on a balloon that appeared on the VR screen. The intervention period was 5 days. MAIN OUTCOME MEASURES: The primary outcome was the participants' scores on a stimulus-driven attention test (SAT) using the reaction time. The stimuli of the SAT were divided into 6 blocks of 3 lines on each side (-3 to +3). The secondary outcomes were their scores on the Behavioral Intention Test conventional, Catherine Bergego Scale, and straight ahead pointing tests. RESULTS: In the SAT, there were significant interaction effects of reaction time between time and group factors in left-2, right+2, and right+3. The SR+BS and SR groups showed significant improvements in the reaction time of left-2 and right+3 compared with the control group. Moreover, the SR+BS group showed a significant improvement in the reaction time of left-2, which was the neglected space, compared with the SR group. However, there were no significant interaction effects of Behavioral Intention Test conventional, Catherine Bergego Scale, and straight ahead pointing. CONCLUSIONS: Our results suggest that the use of stimulus response tasks using VR combined with background shifts may improve left-sided USN.


Subject(s)
Perceptual Disorders , Reaction Time , Virtual Reality , Humans , Male , Female , Double-Blind Method , Aged , Middle Aged , Perceptual Disorders/rehabilitation , Perceptual Disorders/physiopathology , Perceptual Disorders/etiology , Attention/physiology , Stroke Rehabilitation/methods , Stroke/complications
14.
Neuropsychologia ; 201: 108901, 2024 Aug 13.
Article in English | MEDLINE | ID: mdl-38704116

ABSTRACT

Whether attentional deficits are accompanied by visuomotor impairments following posterior parietal lesions has been debated for quite some time. This single-case study investigated reaching in a stroke survivor (E.B.) with left visual neglect and visual extinction following right temporo-parietal-frontal strokes. Unlike most neglect patients, E.B. did not present left hemiparesis, homonymous hemianopia nor show evidence of motor neglect or extinction allowing us to examine, for the first time, if lateralised attentional deficits co-occur with deficits in peripheral and bimanual reaching. First, we found a classic optic ataxia field effect: E.B.'s accuracy was impaired when reaching to peripheral targets in her neglected left visual field (regardless of the hand used). Second, we found a larger bimanual cost for movement time in E.B. than controls when both hands reached to incongruent locations. E.B.'s visuomotor profile is similar to the one of patients with optic ataxia showing that attentional deficits are accompanied by visuomotor deficits in the affected field.


Subject(s)
Functional Laterality , Perceptual Disorders , Psychomotor Performance , Stroke , Humans , Female , Perceptual Disorders/etiology , Perceptual Disorders/physiopathology , Stroke/complications , Stroke/physiopathology , Psychomotor Performance/physiology , Functional Laterality/physiology , Middle Aged , Extinction, Psychological/physiology , Visual Fields/physiology , Aged , Visual Perception/physiology
15.
Schizophr Res ; 269: 1-8, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38703518

ABSTRACT

One of the main tasks of the human visual system is to organize the temporal flow of visual events into meaningful patterns. It has been suggested that segregation/integration of continuous visual stimuli relies on temporal windows that are phase-locked to brain oscillations in the alpha frequency range (~10 Hz). From a behavioral point of view, the balance between integration and segregation is reflected in visual temporal acuity: the ability to perceive a small temporal gap between two identical stimuli. Disruption of this balance may lead to impairment of perceptual organization processes. Notably, schizophrenia, a condition characterized by unusual perceptual experiences, has been associated with abnormal temporal processing of sensory stimuli and aberrant oscillations. We asked a large cohort of healthy participants to complete an online version of the two-flash fusion task and two questionnaires for schizotypal personality traits to investigate individual differences in the temporal resolution of perception, particularly its relationship with anomalous perceptual experiences. We found that two-flash discrimination acuity declines with age and that schizotypal traits are associated with better performances. Although this association was strong for perceptual and cognitive subscales, we found that this result could not be attributed to response biases (e.g., hallucination of two flashes). While these results appear to contrast with findings of slower alpha rhythms and sensory processing in schizotypy, we propose that a faster visual rate could be the consequence of an oscillopathy or a disconnection between different sensory modalities and their physiological pacemaker.


Subject(s)
Schizotypal Personality Disorder , Humans , Male , Female , Adult , Schizotypal Personality Disorder/physiopathology , Young Adult , Adolescent , Middle Aged , Photic Stimulation , Visual Acuity/physiology , Visual Perception/physiology , Surveys and Questionnaires , Aged , Perceptual Disorders/physiopathology , Perceptual Disorders/etiology , Discrimination, Psychological/physiology
16.
J Neurosurg ; 141(3): 624-633, 2024 Sep 01.
Article in English | MEDLINE | ID: mdl-38608308

ABSTRACT

OBJECTIVE: Spatial neglect is a debilitating condition observed in patients with right-sided brain injuries in whom there is defective awareness of the contralesional space. Although classically considered a right parietal lobe deficit, there has been increasing interest in the specific white matter (WM) architecture subserving spatial neglect. Patients who have lesions associated with chronic disruptions in visuospatial networks are of significant relevance in elucidating the WM tracts associated with spatial attention. In this study, the authors used two independent analytical methods to examine the relationship between WM connectivity changes and spatial attention. METHODS: Thirty patients with right-sided glioma underwent diffusion tensor imaging (DTI) tractography and neuropsychological testing prior to tumor resection. Spatial neglect was assessed using the Bells Test. Diffusion connectometry analysis was performed to calculate the probability of injury to 55 WM tracts. Next, quantitative DTI tractography was used to reconstruct 9 major WM tracts and obtain fractional anisotropy (FA) and streamline number values as indices of connectivity. Differences in connectivity were assessed between patients with neglect and controls. RESULTS: Of the WM tracts analyzed by diffusion connectometry, only the right posterior segment of the arcuate fasciculus (psAF) showed a higher probability of disconnection in patients with evidence of hemispatial neglect compared to tract reconstructions of previously published healthy controls (hemineglect: 42% ± 12.5%, vs control: 6.3% ± 4.8% [mean ± SEM]; p < 0.05). Of the WM tracts reconstructed by DTI tractography, only the right psAF demonstrated consistently lower indices of connectivity based on the mean streamline number (hemineglect: 550.35 ± 183.41, vs control: 1407.01 ± 319.93; p < 0.05) and FA value (hemineglect: 0.40 ± 0.013, vs control: 0.44 ± 0.0063; p < 0.05) in patients who demonstrated neglect compared to controls. The right long segment of the arcuate fasciculus, inferior frontooccipital fasciculus, and inferior longitudinal fasciculus also demonstrated a lower streamline number, but not a lower FA value, in patients with evidence of hemineglect. CONCLUSIONS: These findings suggest that parietotemporal networks mediated by the right psAF may play a critical role in visuospatial attention. This analysis may help to disentangle the organization of the visuospatial attention networks, predict deficits in patients with glioma, and optimize surgical planning.


Subject(s)
Brain Neoplasms , Diffusion Tensor Imaging , Glioma , Perceptual Disorders , White Matter , Humans , Perceptual Disorders/diagnostic imaging , Perceptual Disorders/etiology , Male , Female , Middle Aged , Adult , White Matter/diagnostic imaging , White Matter/pathology , Brain Neoplasms/diagnostic imaging , Brain Neoplasms/surgery , Brain Neoplasms/pathology , Aged , Glioma/diagnostic imaging , Glioma/pathology , Glioma/surgery , Glioma/complications , Neuropsychological Tests , Neural Pathways/diagnostic imaging
17.
Cogn Behav Neurol ; 37(2): 82-95, 2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38682873

ABSTRACT

Individuals with acquired brain injury have reported subjective complaints of depth perception deficits, but few have undergone objective assessments to confirm these deficits. As a result, the literature currently lacks reports detailing the correlation between subjective depth perception deficits and objective stereoscopic vision deficits in individuals with acquired brain injury, particularly those cases that are characterized by a clearly defined lesion. To investigate this relationship, we recruited three individuals with acquired brain injury who experienced depth perception deficits and related difficulties in their daily lives. We had them take neurologic, ophthalmological, and neuropsychological examinations. We also had them take two types of stereoscopic vision tests: a Howard-Dolman-type stereoscopic vision test and the Topcon New Objective Stereo Test. Then, we compared the results with those of two control groups: a group with damage to the right hemisphere of the brain and a group of healthy controls. Performance on the two stereoscopic vision tests was severely impaired in the three patients. One of the patients also presented with cerebral diplopia. We identified the potential neural basis of these deficits in the cuneus and the posterior section of the superior parietal lobule, which play a role in vergence fusion and are located in the caudal region of the dorso-dorsal visual pathway, which is known to be crucial not only for visual spatial perception, but also for reaching, grasping, and making hand postures in the further course of that pathway.


Subject(s)
Brain Injuries , Depth Perception , Perceptual Disorders , Humans , Brain Injuries/complications , Brain Injuries/psychology , Brain Injuries/physiopathology , Depth Perception/physiology , Neuropsychological Tests/statistics & numerical data , Perceptual Disorders/etiology , Perceptual Disorders/physiopathology , Vision Disorders/psychology , Vision Disorders/etiology
18.
Neuropsychologia ; 199: 108883, 2024 07 04.
Article in English | MEDLINE | ID: mdl-38599567

ABSTRACT

Left smooth pursuit eye movement training in response to large-field visual motion (optokinetic stimulation) has become a promising rehabilitation method in left spatial inattention or neglect. The mechanisms underlying the therapeutic effect, however, remain unknown. During optokinetic stimulation, there is an error in visual localisation ahead of the line of sight. This could indicate a change in the brain's estimate of one's own direction of gaze. We hypothesized that optokinetic stimulation changes the brain's estimate of gaze. Because this estimate is critical for coding the locus of attention in the visual space relative to the body and across sensory modalities, its change might underlie the change in spatial attention. Here, we report that in healthy participants optokinetic stimulation causes not only a directional bias in the proprioceptive signal from the extraocular muscles, but also a corresponding shift of the locus of attention. Both changes outlasted the period of stimulation. This result forms a step in investigating a causal link between the adaptation in the sensorimotor gaze signals and the recovery in spatial neglect.


Subject(s)
Attention , Fixation, Ocular , Perceptual Disorders , Humans , Attention/physiology , Male , Perceptual Disorders/rehabilitation , Perceptual Disorders/physiopathology , Perceptual Disorders/etiology , Female , Adult , Fixation, Ocular/physiology , Photic Stimulation , Space Perception/physiology , Young Adult , Motion Perception/physiology , Proprioception/physiology , Pursuit, Smooth/physiology
19.
J Neurosci ; 44(21)2024 May 22.
Article in English | MEDLINE | ID: mdl-38565290

ABSTRACT

Left-sided spatial neglect is a very common and challenging issue after right-hemispheric stroke, which strongly and negatively affects daily living behavior and recovery of stroke survivors. The mechanisms underlying recovery of spatial neglect remain controversial, particularly regarding the involvement of the intact, contralesional hemisphere, with potential contributions ranging from maladaptive to compensatory. In the present prospective, observational study, we assessed neglect severity in 54 right-hemispheric stroke patients (32 male; 22 female) at admission to and discharge from inpatient neurorehabilitation. We demonstrate that the interaction of initial neglect severity and spared white matter (dis)connectivity resulting from individual lesions (as assessed by diffusion tensor imaging, DTI) explains a significant portion of the variability of poststroke neglect recovery. In mildly impaired patients, spared structural connectivity within the lesioned hemisphere is sufficient to attain good recovery. Conversely, in patients with severe impairment, successful recovery critically depends on structural connectivity within the intact hemisphere and between hemispheres. These distinct patterns, mediated by their respective white matter connections, may help to reconcile the dichotomous perspectives regarding the role of the contralesional hemisphere as exclusively compensatory or not. Instead, they suggest a unified viewpoint wherein the contralesional hemisphere can - but must not necessarily - assume a compensatory role. This would depend on initial impairment severity and on the available, spared structural connectivity. In the future, our findings could serve as a prognostic biomarker for neglect recovery and guide patient-tailored therapeutic approaches.


Subject(s)
Diffusion Tensor Imaging , Perceptual Disorders , Recovery of Function , Stroke , White Matter , Humans , Male , Female , Perceptual Disorders/etiology , Perceptual Disorders/physiopathology , Perceptual Disorders/rehabilitation , Stroke/complications , Stroke/diagnostic imaging , Stroke/physiopathology , Aged , White Matter/diagnostic imaging , White Matter/pathology , Middle Aged , Recovery of Function/physiology , Functional Laterality/physiology , Prospective Studies , Severity of Illness Index , Neural Pathways/physiopathology , Neural Pathways/diagnostic imaging , Neural Pathways/pathology , Aged, 80 and over
20.
Brain Behav ; 14(5): e3496, 2024 May.
Article in English | MEDLINE | ID: mdl-38688878

ABSTRACT

INTRODUCTION: The internal representation of verticality could be disturbed when a lesion in the central nervous system (CNS) affects the centers where information from the vestibular, visual, and/or somatosensory systems, increasing the risk of falling. OBJECTIVE: The aim was to evaluate the vestibular and somatosensory contribution to the verticality pattern in patients with stroke and other neurological disorders. METHODS: A literature search was performed in PubMed, Scopus, Web of Science, and CINAHL databases. Cross-sectional, case-control, and cohort studies comparing body verticality in patients with stroke or CNS diseases (CNSD) versus healthy controls were selected. Subjective postural vertical (SPV) in roll and pitch planes was used as the primary variable. RESULTS: Ten studies reporting data from 390 subjects were included. The overall effect for CNSD patients showed a misperception of body verticality in roll (standardized mean difference [SMD] = 1.05; 95% confidence interval [CI] .84-1.25) and pitch planes (SMD = 1.03; 95% CI .51-1.55). In subgroup analyses, a high effect was observed in the perception of SPV both in roll and pitch planes in stroke (p = .002) and other CNSD (p < .001). CONCLUSION: These findings suggest a potential misperception of SPV in patients with stroke and other neurological disturbances. Patients with CNSD could present an alteration of vestibular and somatosensory contribution to verticality construction, particularly stroke patients with pusher syndrome (PS), followed by those with PS combined with hemineglect.


Subject(s)
Perceptual Disorders , Humans , Nervous System Diseases/physiopathology , Perceptual Disorders/physiopathology , Perceptual Disorders/etiology , Proprioception/physiology , Space Perception/physiology , Stroke/physiopathology , Stroke/psychology
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