| |
Abstract:
Abstract: Working memory (WM) disturbances have been
hypothesized to underlie the broad range of cognitive impairments
observed in patients with schizophrenia. WM studies generally
assume intact information processing (IP). However, there is
increasing evidence of early visual IP impairments in
schizophrenia. Therefore, we decided to examine whether: 1)
patients exhibit visual spatial and object IP impairments; and 2)
patients exhibit spatial and object WM impairments when initial IP
performance is controlled. In the visual IP experiment, two
abstract targets were presented on a computer screen for a preset
duration. After a 250-msec delay, the subject judged whether a
third stimulus matched the targets in either shape or location.
There were 8 40-trial blocks and the stimulus duration ranged from
15 to 2500 msec. Patients performed significantly more poorly on
both the spatial and object IP tasks, regradless of stimulus
duration. In the WM experiment, the same spatial and object target
stimuli were used, except the target presentation duration varied
individually to achieve an 80-90% correct IP performance level, and
there was a 3-sec delay between the target and test stimuli.
Patients performed significantly worse on the spatial but not
object WM condition. These results suggest that when the level of
IP impairments is controlled, then patients with schizophrenia
exhibit specific visuospatial WM impairments.
|
