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Abstract:
Schizophrenia is characterized by a range of sensory and
cognitive symptoms, but is typically attributed to higher-order
impairment. ERP recordings (64-channel) were used to examine
integrity of processing in sensory object recognition areas in
schizophrenia patients and age-matched controls. Prior work in
normals revealed a bilateral component (Ncl-290msec) that tracks
perceptual closure processes as versions of an object are presented
from most to least fragmented. Ncl was largest when recognition was
achieved and was incrementally reduced in amplitude at the more
fragmented levels prior to recognition (Doniger et al., 2000).
Scalp current density maps of Ncl localized it over
lateral-occipital object recognition areas. This study used the
same task to examine object recognition in schizophrenia patients.
Patients required more visual information before object recognition
could be achieved. This behavioral impairment was accompanied by a
reduced Ncl that lacked the characteristic build in activity. An
early P1 decrement was evident over parietal scalp whose topography
reflected greater impairment in dorsal versus ventral generators.
While P1 and Ncl were reduced, the intervening ventral N1 component
was intact, suggesting that processing dysfunction is only evident
in ventral areas following aberrant dorsal activity.
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