No abrupt change in visual hemineglect from near to far space

Cowey, Alan; Small, Marian; Ellis, Simon J.

doi:10.1016/s0028-3932(98)00071-2

Cited by 80 publications

(39 citation statements)

References 7 publications

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“…They argue that the gradient effect, when observed, may be related to the great number of frontal and parietal cortical visual areas whose neurons are sensitive to the distance of the visual stimuli. As a result, if a lesion affects a region chiefly or exclusively concerned with near or far space, there will be ample opportunities for compensation (Cowey et al, 1999). Therefore, on the basis of these arguments, we may advance the hypothesis that also in our patient a discrete mechanism for far space coding was still working, whereas a separated mechanism of near space coding was damaged by the lesion.…”

Section: Discussionmentioning

confidence: 55%

“…The performance of a task depends not only on where stimuli are presented in space, but also on the specific cognitive system underlying the task that, if intact, may overcome the spatial problem. Moreover, as suggested by Cowey et al (1999) and by Vuilleumier et al (1998), the different motor programs used for performing the tasks may also influence different performances in different tasks. The lesion could affect specific motor programs differently, therefore causing different pattern of results.…”

Section: Discussionmentioning

confidence: 99%

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When Far Becomes Near: Remapping of Space by Tool Use

Berti

Frassinetti

2000

Journal of Cognitive Neuroscience

638

398

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Abstract& Far (extrapersonal) and near (peripersonal) spaces are behaviorally defined as the space outside the hand-reaching distance and the space within the hand-reaching distance. Animal and human studies have confirmed this distinction, showing that space is not homogeneously represented in the brain. In this paper we demonstrate that the coding of space as ''far'' and ''near'' is not only determined by the hand-reaching distance, but it is also dependent on how the brain represents the extension of the body space. We will show that when the cerebral representation of body space is extended to include objects or tools used by the subject, space previously mapped as far can be remapped as near. Patient P.P., after a right hemisphere stroke, showed a dissociation between near and far spaces in the manifestation of neglect. Indeed, in a line bisection task, neglect was apparent in near space, but not in far space when bisection in the far space was performed with a projection lightpen. However, when in the far space bisection was performed with a stick, used by the patient to reach the line, neglect appeared and was as severe as neglect in the near space. An artificial extension of the patient's body (the stick) caused a remapping of far space as near space. &

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Section: Discussionmentioning

confidence: 55%

Section: Discussionmentioning

confidence: 99%

When Far Becomes Near: Remapping of Space by Tool Use

Berti

Frassinetti

2000

Journal of Cognitive Neuroscience

638

398

View full text Add to dashboard Cite

show abstract

“…This finding demonstrated, for the first time in humans, that unawareness for stimuli can be restricted to a specific sector of space. The finding of the opposite dissociation (more severe neglect in far space than in near space) confirmed that, also for humans, far and near space can be separately coded by the brain (Cowey et al, 1994(Cowey et al, , 1999Vuillemieur et al, 1997) Interestingly, a recent PET study has confirmed the anatomical distinction between near and far space coding in humans (Weiss et al, 2000).…”

Section: Coding Of Far and Near Space In Humansmentioning

confidence: 67%

Coding of Far and Near Space in Neglect Patients

Berti

Smania²,

Allport

2001

NeuroImage

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Far (extrapersonal) and near (peripersonal) spaces are behaviorally defined as the space outside armreaching distance and the space within arm-reaching distance. Animal and human studies have shown that this behavioral distinction corresponds in the brain to a composite neural architecture for space representation. In this paper we discuss how the activation of the neural correlates of far and near space can be modulated by the use of tools that change the effective spatial relationship between the agent's body and the target object. When subjects reach for a far object with a tool, it is possible to show that far space is remapped as near. We shall also argue that space remapping may not occur when far space is reached by walking instead of using a tool.

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“…What could explain the phenomenal continuity of space? A partial answer has been provided by Cowey et al (1999), investigating whether the boundary between near and far regions of space is abrupt or progressive. To address this question, they asked neglect patients to perform a series of line bisection tasks, at six increasing distances, from 25 to 400cm.…”

Section: What Is Body Schema?mentioning

confidence: 99%