T Cosentino | PubMed Health

PubMed2000

TENS modulates spatial reorientation in neglect patients.

The existence of separate systems for processing geometric and non-geometric spatial information was studied. Twelve neglect patients were asked to reorient themselves in a room using only geometric information or to integrate this information with relevant visual cues both in the presence and in the absence of transcutaneous electrical neural stimulation (TENS). In the absence of TENS, all patients were greatly impaired in coding geometric information, and they had difficulty in coding non-geometric information. TENS significantly improved the ability to code shape-based representation, but is ineffective with non-geometric representations (such as color). The data support previous findings on neglect patients suggesting the presence of separate, independent neural systems subserving different types of space representation.

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PubMed1998

Evidence for separate allocentric and egocentric space processing in neglect patients.

Spatial orientation was investigated in two different conditions: (a) when the shape of the enclosure was the only available information; (b) when a clearly perceivable visual cue was added. Three groups of subjects were investigated: normal controls, right brain-damaged patients without and with hemispatial neglect. The performance of the first two groups clearly demonstrated the capacity to use the geometric properties of the environment and to integrate this information with an additional visual cue. Considered as a group, patients with hemispatial neglect were able to use the shape of the environment and, to a lesser extent, the additional visual cue. However, individual differences suggest two opposite performance patterns: two patients responded randomly when the shape of the environment was the only available information, and they improved considerably when the cue was offered; two other patients showed normal competence in dealing with the geometrical properties of the environment, but were unable to take advantage of the cue. The different lesion site in these two types of patients suggests a possible dissociation of processing based upon allocentric or egocentric coding of space in humans as well as in animals.

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