Visual processing features in patients with visual spatial neglect recovering from right-hemispheric stroke

Abstract The most common excitatory neurotransmitter in the central nervous system, glutamate, is loaded into synaptic vesicles by vesicular glutamate transporters (VGluTs). The primary isoforms, VGluT1 and 2, are expressed in complementary patterns throughout the brain and correlate with short-term synaptic plasticity. VGluT1 deficiency is observed in certain neurological disorders, and hemizygous (VGluT1+/−) mice display increased anxiety and depression, altered sensorimotor gating, and impairments in learning and memory. The synaptic mechanisms underlying these behavioral deficits are unknown. Here, we show that VGluT1+/− mice had decreased visual processing speeds during a sustained visual-spatial attention task. Furthermore, in vitro recordings of corticothalamic (CT) synapses revealed dramatic reductions in short-term facilitation, increased initial release probability, and earlier synaptic depression in VGluT1+/− mice. Our electron microscopy results show that VGluT1 concentration is reduced at CT synapses of hemizygous mice, but other features (such as vesicle number and active zone size) are unchanged. We conclude that VGluT1-haploinsuficiency decreases the dynamic range of gain modulation provided by CT feedback to the thalamus, and this deficiency contributes to the observed attentional processing deficit. We further hypothesize that VGluT1 concentration regulates release probability by applying a “brake” to an unidentified presynaptic protein that typically acts as a positive regulator of release.

Download Full-text

Development of the Halifax Visual Scanning Test: A New Measure of Visual-Spatial Neglect for Personal, Peripersonal, and Extrapersonal Space

Journal of the International Neuropsychological Society ◽

10.1017/s135561771900002x ◽

2019 ◽

Vol 25 (05) ◽

pp. 490-500

Author(s):

Christiane E. Whitehouse ◽

Janet Green ◽

Sarah M. Giles ◽

Rosanna Rahman ◽

Jamesie Coolican ◽

...

Keyword(s):

Right Hemisphere ◽

Assessment Tool ◽

Spatial Neglect ◽

Visual Scanning ◽

Control Data ◽

Normative Database ◽

Rehabilitation Outcomes ◽

Visual Spatial ◽

Extrapersonal Space ◽

Stroke Group

Objectives: Visual-spatial neglect is a common attentional disorder after right-hemisphere stroke and is associated with poor rehabilitation outcomes. The presence of neglect symptoms has been reported to vary across personal, peripersonal, and extrapersonal space. Currently, no measure is available to assess neglect severity equally across these spatial regions and may be missing subsets of symptoms or patients with neglect entirely. We sought to provide initial construct validity for a novel assessment tool that measures neglect symptoms equally for these spatial regions: the Halifax Visual Scanning Test (HVST). Methods: In Study I, the HVST was compared to conventional measures of neglect and functional outcome scores (wheelchair navigation) in 15 stroke inpatients and 14 healthy controls. In Study II, 19 additional controls were combined with the control data from Study I to establish cutoffs for impairment. Patterns of neglect in the stroke group were examined. Results: In Study I, performance on all HVST subtests were correlated with the majority of conventional subtests and wheelchair navigation outcomes. In Study II, neglect-related deficits in visual scanning showed dissociations across spatial regions. Four inpatients exhibited symptoms of neglect on the HVST that were not detected on conventional measures, one of which showed symptoms in personal and extrapersonal space exclusively. Conclusions: The HVST appears a useful measure of neglect symptoms in different spatial regions that may not be detected with conventional measures and that correlates with functional wheelchair performance. Preliminary control data are presented and further research to add to this normative database appears warranted. (JINS, 2019, 25, 490–500)

Download Full-text

Impact of Visual-Spatial Neglect on Stroke Functional Outcomes, Discharge Destination and Maintenance of Improvement Post-Discharge

British Journal of Occupational Therapy ◽

10.1177/030802260907200508 ◽

2009 ◽

Vol 72 (5) ◽

pp. 219-225 ◽

Cited By ~ 4

Author(s):

Maria Stella Stein ◽

David Maskill ◽

Louise Marston

Keyword(s):

Occupational Therapy ◽

Functional Outcomes ◽

Discharge Planning ◽

Inpatient Rehabilitation ◽

Functional Mobility ◽

Spatial Neglect ◽

Discharge Destination ◽

Post Discharge ◽

Visual Spatial

This study evaluated basic functional mobility in 25 patients with stroke and visual-spatial neglect during inpatient rehabilitation and early follow-up. Seven patients with neglect and 12 patients without neglect were discharged home and the rest to institutions. Patients without neglect achieved higher outcomes in a shorter time (mean 52 and 79 days respectively). All patients discharged home continued to improve at least up to 5 weeks post-discharge. The patients discharged to institutions achieved lower outcomes overall and quickly deteriorated to admission levels post-discharge. The results inform occupational therapy practice in the areas of assessment, discharge planning, destination and expected functional mobility outcomes in the community.

Download Full-text

Visual-spatial neglect in a child following sub-cortical tumor resection

Developmental Medicine & Child Neurology ◽

10.1111/j.1469-8749.2002.tb00785.x ◽

2007 ◽

Vol 44 (3) ◽

pp. 191-200

Author(s):

Rebecca L Billingsley ◽

Frederick F Lang ◽

John M Slopis ◽

Gregory W Schrimsher ◽

Joann L Ater ◽

...

Keyword(s):

Tumor Resection ◽

Spatial Neglect ◽

Visual Spatial

Download Full-text

Family Participation Can Improve Unilateral Spatial Neglect in Patients with Acute Right Hemispheric Stroke

European Neurology ◽

10.1159/000286517 ◽

2010 ◽

Vol 63 (3) ◽

pp. 170-175 ◽

Cited By ~ 10

Author(s):

A. Osawa ◽

S. Maeshima

Keyword(s):

Spatial Neglect ◽

Family Participation ◽

Unilateral Spatial Neglect ◽

Hemispheric Stroke

Download Full-text

The Connectivity of the Human Pulvinar: A Diffusion Tensor Imaging Tractography Study

International Journal of Biomedical Imaging ◽

10.1155/2008/789539 ◽

2008 ◽

Vol 2008 ◽

pp. 1-5 ◽

Cited By ~ 52

Author(s):

Sandra E. Leh ◽

M. Mallar Chakravarty ◽

Alain Ptito

Keyword(s):

Diffusion Tensor Imaging ◽

Visual Processing ◽

Animal Studies ◽

Diffusion Tensor ◽

Human Vision ◽

Subcortical Structures ◽

Fiber Tracts ◽

Visual Spatial ◽

Visual Areas

Previous studies in nonhuman primates and cats have shown that the pulvinar receives input from various cortical and subcortical areas involved in vision. Although the contribution of the pulvinar to human vision remains to be established, anatomical tracer and electrophysiological animal studies on cortico-pulvinar circuits suggest an important role of this structure in visual spatial attention, visual integration, and higher-order visual processing. Because methodological constraints limit investigations of the human pulvinar's function, its role could, up to now, only be inferred from animal studies. In the present study, we used an innovative imaging technique, Diffusion Tensor Imaging (DTI) tractography, to determine cortical and subcortical connections of the human pulvinar. We were able to reconstruct pulvinar fiber tracts and compare variability across subjects in vivo. Here we demonstrate that the human pulvinar is interconnected with subcortical structures (superior colliculus, thalamus, and caudate nucleus) as well as with cortical regions (primary visual areas (area 17), secondary visual areas (area 18, 19), visual inferotemporal areas (area 20), posterior parietal association areas (area 7), frontal eye fields and prefrontal areas). These results are consistent with the connectivity reported in animal anatomical studies.

Download Full-text

Video-Oculography During Free Visual Exploration to Detect Right Spatial Neglect in Left-Hemispheric Stroke Patients With Aphasia: A Feasibility Study

Frontiers in Neuroscience ◽

10.3389/fnins.2021.640049 ◽

2021 ◽

Vol 15 ◽

Author(s):

Brigitte C. Kaufmann ◽

Dario Cazzoli ◽

Monica Koenig-Bruhin ◽

René M. Müri ◽

Tobias Nef ◽

...

Keyword(s):

Spatial Neglect ◽

Visual Exploration ◽

Healthy Controls ◽

Stroke Patients ◽

Calibration And Validation ◽

Video Oculography ◽

Hemispheric Stroke ◽

The Mean ◽

Highly Correlated ◽

Exploration Area

Spatial neglect has been shown to occur in 17–65% of patients after acute left-hemispheric stroke. One reason for this varying incidence values might be that left-hemispheric stroke is often accompanied by aphasia, which raises difficulties in assessing attention deficits with conventional neuropsychological tests entailing verbal instructions. Video-oculography during free visual exploration (FVE) requires only little understanding of simple non-verbal instruction and has been shown to be a sensitive and reliable tool to detect spatial neglect in patients with right-hemispheric stroke. In the present study, we aimed to investigate the feasibility of FVE to detect neglect in 10 left-hemispheric stroke patients with mild to severe aphasia as assessed by means of the Token Test, Boston Naming Test and Aachener Aphasie Test. The patient’s individual deviation between eye movement calibration and validation was recorded and compared to 20 age-matched healthy controls. Furthermore, typical FVE parameters such as the landing point of the first fixation, the mean gaze position (in ° of visual angle), the number and duration of visual fixations and the mean visual exploration area were compared between groups. In addition, to evaluate for neglect, the Bells cancellation test was performed and neglect severity in daily living was measured by means of the Catherine Bergego Scale (CBS). Our results showed that the deviation between calibration and validation did not differ between aphasia patients and healthy controls highlighting its feasibility. Furthermore, FVE revealed the typical neglect pattern with a significant leftward shift in visual exploration bahaviour, which highly correlated with neglect severity as assessed with CBS. The present study provides evidence that FVE has the potential to be used as a neglect screening tool in left-hemispheric stroke patients with aphasia in which compliance with verbal test instructions may be compromised by language deficits.

Download Full-text

A-249 Evidence for Frontal Lobe Involvement in the Visual Processing Streams

Archives of Clinical Neuropsychology ◽

10.1093/arclin/acaa068.249 ◽

2020 ◽

Vol 35 (6) ◽

pp. 1044-1044

Author(s):

Leonard S ◽

Hall T

Keyword(s):

Frontal Lobe ◽

Visual Processing ◽

Visual Memory ◽

Word Reading ◽

Parietal Lobe ◽

Occipital Lobe ◽

Current Case ◽

Verbal Skills ◽

Orbital Roof ◽

Visual Spatial

Abstract Objective Extant literature supports the “Two-Stream Hypothesis” of visual processing including a ventral stream (connecting the occipital lobe to the temporal lobe) and a dorsal stream (connecting the occipital lobe to the parietal lobe), but is not traditionally believed to involve the frontal lobe. Method “Eddie”, a healthy 14-year-old male, sustained a penetrating brain injury by accidentally lodging a pool cue through his right orbital bones and piercing his right frontal lobe through to the skull. He was ambulatory, awake, and alert on arrival to the ED, with a laceration, swelling, and bleeding of the eyelid. A cranial CT revealed a complex orbital roof fracture, injury to the orbit, and right frontal contusions. Eddie underwent a right supraorbital craniotomy with repair of the orbital roof fracture and debridement of bony fragments. Post-operative MRI revealed right frontal parenchymal edema and patchy areas of contusion. Results Neuropsychological evaluation revealed a robust cognitive reserve including verbal skills, working memory, processing speed, and word reading skills in the high average. Eddie demonstrated significant discrepancies in visually mediated skills including relatively weaker visual–spatial skills (24 standard score (SS) points lower than verbal skills), fluid reasoning with visual problem-solving (30 SS points lower than verbal skills), low average judgment of line orientation, and a discrepancy between verbal and visual memory. He also demonstrated mild difficulties consistent with his right orbito-frontal injury including weaknesses regarding impulsivity, self-monitoring, planning, and task approach. Conclusions The current case demonstrates possible involvement of the frontal lobe in the visual processing pathways.

Download Full-text

Sensory gain control (amplification) as a mechanism of selective attention: electrophysiological and neuroimaging evidence

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.1998.0281 ◽

1998 ◽

Vol 353 (1373) ◽

pp. 1257-1270 ◽

Cited By ~ 621

Author(s):

Steven A. Hillyard ◽

Edward K. Vogel ◽

Steven J. Luck

Keyword(s):

Selective Attention ◽

Visual Processing ◽

Early Stage ◽

Gain Control ◽

Brain Potentials ◽

Sensory Pathways ◽

Visual Spatial Attention ◽

Cortical Areas ◽

Visual Spatial ◽

Behavioral Studies

Both physiological and behavioral studies have suggested that stimulus–driven neural activity in the sensory pathways can be modulated in amplitude during selective attention. Recordings of event–related brain potentials indicate that such sensory gain control or amplification processes play an important role in visual–spatial attention. Combined event–related brain potential and neuroimaging experiments provide strong evidence that attentional gain control operates at an early stage of visual processing in extrastriate cortical areas. These data support early selection theories of attention and provide a basis for distinguishing between separate mechanisms of attentional suppression (of unattended inputs) and attentional facilitation (of attended inputs).

Download Full-text