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Abstract:
We tested the capability of brain damaged patients with
unimodal (visual, tactile or auditory) extinction (E+) or without
extinction (E-) to process multimodal stimuli. The experimental,
computer-controlled stimuli consisted of series of single (left, L
or right, R) or trimodal stimuli delivered simultaneously within a
single hemispace (3 L or 3 R) or across-hemispaces (2L/1R or
2R/1L). Visual and auditory stimuli were presented close to the
hands (near condition) or 60 cm away from the hands (far
condition). Patients were requested to report verbally on the
modality and side of the stimuli. Correct number and modality
detections of single and triple stimuli in the near and far
conditions were compared in the two groups. Detection of single
stimuli was very high in the two groups and comparable in the
different conditions. Detection of trimodal stimuli in E- was
significantly more accurate in the near than the far conditions. An
opposite trend was observed in E+. Since detection of single
stimuli was not different in the near and far space, the
space-related performance for trimodal stimuli can be attributed to
higher-order factors subserving multisensory integration of stimuli
in the peripersonal space, a process which appears impaired in E+
patients.
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