China
Africa
Explore chapters and articles related to this topic
Disruptions in physical substrates of vision following traumatic brain injury
Published in Mark J. Ashley, David A. Hovda, Traumatic Brain Injury, 2017
Beyond V5, the next major area is that of the angular gyrus. The angular gyrus is in the heart of the posterior association area where multisensory integration occurs and also is important for spatial perception. In this area, SFLII projects forward, connecting the posterior association areas with the anterior association areas and the limbic association areas. This is a main component of visual spatial attention and plays a role in visual and ocular aspects of spatial awareness. Space is defined as boundless 3-D space in which objects and events have related position and direction. It serves as a background to place and locate visual representations. It has vertical, horizontal, and radial axes. Tasks have been developed that are available to assist at the bedside to differentiate disorders of these spatial axes.29 Our subjective experience strongly suggests that we have direct access to a single, coherent, and overlapping representation of space as it is perceived as an instant, seamless entity. There is, however, no evidence for the existence of a single topographic representation of space available for incorporating each type of sensory input and generating every type of motor output. Space is constituted by a multiple representation of space in a variety of coordinate frames and linked to separate output systems to guide specific motor effectors. Hemispheric control of attention is governed by hemispace.15 Visual hemispace is based on the orientation of head and body coordinates (craniotopic) with visual contributions to the retinotopic coordinates. Space has two components, the contralateral half of the body (personal) and extrapersonal space. Parietal and frontal cortices construct multiple spatial representations in order to carry out attentional and sensory motor goals. Spatial cognition has three progressive stages: a dedicated perceptual attentional stage, a representative stage, and a motor-attention component.30 Visual cognition is involved in the visual perceptual aspects, i.e., the visual representative component, but only contributes to the multisensory nature of the input and output systems. The SFLII provides the visual component for spatial cognition specifically in this area by converting retinotopic to craniotopic coordinates. The right hemisphere extends control predominately over the left hemispace but also partially over the right hemispace whereas the left hemisphere governs only its contralateral hemispace. Thus, the right posterior parietal area is dominant for spatial attention.
Assessing working memory capacity through picture span and feature binding with visual-graphic symbols during a visual search task with typical children and adults
Published in Augmentative and Alternative Communication, 2021
Barry T. Wagner, Lauren A. Shaffer, Olivia A Ivanson, James A. Jones
The current research expands knowledge in spatial cognition. First, this study examines working memory capacity during a picture span task requiring the maintenance of symbol identity, location, and sequence. A picture span procedure was used to assess capacity in spatial memory with typical third grade children and adults during visual search of symbols with verbal labels. Span tasks determine the functional limit of how many representations can be kept active in working memory, and often predict abilities in reading comprehension, following directions, and solving problems (Meier & Kane, 2017). Secondly, this study evaluated feature binding, a spatial construct of working memory that explains how symbols, their locations, and sequences are bound together. Research in feature binding is relevant for understanding performance on visuospatial tasks, particularly in situations where task demands exceed working memory capacity. Lastly, involvement of both children and adults allowed the assessment of feature binding along a developmental continuum in a population of typical participants.
Impairments in spatial navigation during walking in patients 70 years or younger with mild stroke
Published in Topics in Stroke Rehabilitation, 2020
Charlotta Hamre, Brynjar Fure, Jorunn Lægdheim Helbostad, Torgeir Bruun Wyller, Hege Ihle-Hansen, Georgios Vlachos, Marie Helene Ursin, Gro Gujord Tangen
Research on navigational impairments in people after stroke has often focused on brain topography using case studies.43 These studies are important for knowledge about brain structure and function but give little information in a clinical setting with a focus on patients’ participation in an everyday life function. Navigational tests can be carried out in real-world situations, with a virtual reality equipment, or with questionnaires.44 Self-report tools can give important information about a person’s perception of navigation ability but are not necessarily associated with performance-based navigation in real-life situations.44 After a stroke, assessments of cognitive function are routinely carried out, and guidelines emphasize visual neglect as an important cognitive function to assess.45 Other aspects of spatial cognition, such as navigational abilities, have rarely been addressed, neither in the acute or subacute phase nor in the outpatient clinic.16 Potentially, this could lead to underdiagnosing navigation ability impairments, which in turn might hinder persons with even mild stroke from participating in everyday activities.46
The feasibility and effectiveness of using prism adaptation to treat motor and spatial dysfunction in stroke survivors with multiple incidents of stroke
Published in Topics in Stroke Rehabilitation, 2018
Kimberly Hreha, Glen Gillen, Natalia Noce, Dawn Nilsen
Spatial neglect is a disorder of spatial cognition or a dysfunction of the control of spatial attention that affects perception, memory, motor planning, and executive function.5 Spatial neglect is conventionally characterized by a failure or slowness to attend, orient, and/or make movements towards a stimulus that is presented in the space contralateral to the brain lesion.6 For example, a person with spatial neglect may have difficulty reading or completing wheelchair mobility.7, 8 Individuals with spatial neglect who had significantly more weakness in their arms initially showed less improvement over time (52 weeks) when compared to those without neglect.9 It was hypothesized that people with spatial neglect sustain impairments in motor control because their attention is not focused on their motor skills.10 Spatial neglect, at the acute rehabilitation stage, is documented in 68.7% of stroke survivors.11 Spatial neglect is associated with prolonged hospitalizations, increased risk for falls, and decreased community mobility.11, 12 Ultimately, spatial neglect can lead to long-term functional disability for 30% of stroke survivors.13