| |
Abstract:
Histopathological and neuroimaging studies suggest that there
are abnormalities in the local circuitry and physiology of the
anterior cingulate cortex (ACC) in schizophrenia. Recent imaging
studies suggest that these disturbances are related to cognitive
disability. This region of the brain has been implicated in
executive processes during cognition. Recent event-related fMRI
studies indicate that the ACC serves an evaluative function,
reflecting task conditions that indicate poor performance is likely
and signaling the need to engage strategic processes such as
attention allocation to maintain performance. We studied 14
schizophrenia patients and 14 normal controls using event-related
fMRI and a degraded stimulus version of the AX-CPT task. Stimulus
degradation was individually titrated so that overall difficulty
was comparable for all subjects and error rates were matched across
the two groups. Error related activity in the ACC, an index of the
evaluative function of this region, was contrasted between the
groups. Controls showed the transient, response-related increase in
ACC activity during errors seen in previous studies, while
schizophrenia patients failed to show this response. These results
suggest that one component of cognitive disability in schizophrenia
is a loss of an on-line mechanism for detecting the need to engage
strategic processes, reflecting a disturbance in the function of
the ACC.
|
