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An overview of Bisiach's theory of mental representations and consciousness is presented. Neuropsychological observations on space disorders led Bisiach to consider analogical representations (and not only symbolic representations) as truly ‘cognitive', insofar as they are necessary for the normal functioning of linguistic processes. Bisiach’s approach to the scientific study of consciousness, conceived...
In the late 1970's Edoardo Bisiach and his coworkers provided definitive evidence that spatial unilateral neglect involves a disorder of the internal representation of extra-personal space. A few years later Bisiach and Berti (1987) revived the so far neglected contribution of an Austrian neurologist, Hermann Zingerle (1913). Ninety years ago Zingerle had described the symptom-complex of two right-brain-damaged...
Healthy, right-handed volunteers (six male, six female) either saw or imagined the hands of a clock set at a particular time. In both conditions, they then judged whether the angle between the clock hands was greater than or less than 90 degrees. Subjects pressed one of two response keys to indicate their decision, and hand of response (left/right) was counterbalanced within and between subjects....
A sound that we hear in a natural setting allows us to identify the sound source and to localise it in space. Several lines of evidence indicate that the two aspects are processed in anatomically distinct cortical networks. Auditory areas that are part of the What or Where processing streams have been identified recently in man and in non-human primates. Comparison between anatomical and activation...
There is a growing body of evidence that the processes mediating the allocation of spatial attention within objects may be separable from those governing attentional distribution between objects. In the neglect literature, a related proposal has been made regarding the perception of (within-object) sizes and (between-object) distances. This proposal follows observations that, in size-matching and...
Visual search tasks have standardly been divided into two categories: those in which the target is detected through a serial, attention-driven search and those in which the target is detected rapidly in parallel and, apparently, without attentional processing. Several studies have examined this distinction in patients with hemispatial neglect with the clear prediction that the former, but not the...
Anosognosia for hemiplegia is the denial of the contralesional motor deficits that may follow brain damage. Although this disturbance has been reported in the neurological literature since the beginning of the last century, only few longitudinal studies have addressed the issue of the anatomical substrate of the disorder. Here we present a comprehensive review of the literature on anosognosia for...
Since the pioneering experimental work of Bisiach et al. (1984) on deficits in sound localisation associated with unilateral brain lesions and visual neglect, a number of systematic investigations have examined auditory processing in visuospatial neglect patients. Evidence from a variety of experimental paradigms has revealed some auditory deficits in detection and identification tasks, during bilateral...
Patients with spatial neglect due to right hemisphere pathology may show ‘revisiting’ behaviour during visual search and cancellation tasks, such that previously encountered targets are treated as if they are new discoveries. Revisiting behaviour is particularly evident when no visible trace is left to inform patients that a particular target has already been detected (Husain et al., 2001; Wojciulik...
Recent cognitive models of numerical abilities have postulated that number processing may in part rely on a representation of quantities where magnitude is organized by spatial proximity, along a “mental number line” extending from left to right. We describe four experiments that examined whether such a spatial representation of number would be affected by the presence of unilateral neglect after...
A complex link exists between vision and unilateral spatial neglect (USN). Firstly, USN is not a perceptual deficit, secondly, USN is not necessarily accompanied by a visual deficit and finally, USN can be observed in non-visual modalities as well as in mental spatial imagery. This apparent supramodality of USN stands in sharp contrast to the fact that neglect signs are often more severe and more...
Three patients with visual neglect were tested on their ability to detect target letters at ipsilesional and contralesional locations on a monitor, and at different locations within large shapes on the monitor. When patients were asked to detect targets within the entire monitor, they showed neglect for all the contralesional hemifield. In contrast when they were asked to detect targets within a particular...
This review focuses on Edoardo Bisiach's particular input into the perceptual/premotor taxonomy within the neglect syndrome and assesses arguments and experimental designs that have been presented both for and against the dichotomy. Bisiach made most crucial contributions to this topic as well as increasing insights into the syndrome of hemispatial neglect more generally. Most importantly, he elucidated...
To explain relative leftward overextension in a line extension task by left unilateral neglect subjects, Bisiach et al. (1998) suggested that the representation of space is distorted – i.e., dilated towards the left side. If perception of the velocity of a moving stimulus is due to a calculation of the distance covered per unit time in representational space, then a stimulus with uniform linear motion...
This paper describes for the first time a detailed study of a child with neglect dyslexia. NT is 10-year-old child, with left word-based neglect dyslexia, without clinical signs of visuo-spatial neglect. Since he is a native speaker of Hebrew, which is read from right to left, his neglect dyslexia manifests in omissions and substitutions of final letters. He is severely impaired in single words, with...
A patient with unilateral neglect had to evoke mentally the map of France in two different conditions. In the first condition, he was asked to build an iconic representation of the map of France and to list all the towns that he could ‘see’ on this mental image within two minutes. In the second condition, he had to remember and name as many French towns as possible within two minutes, without being...
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