Abnormal hemodynamics in schizophrenia during an auditory oddball task

Abstract

Background: Schizophrenia is a heterogeneous disorder characterized by diffuse brain abnormalities that affect many facets of cognitive function. One replicated finding in schizophrenia is abnormalities in the neural systems associated with processing salient stimuli in the context of oddball tasks. This deficit in the processing of salience stimuli might be related to abnormalities in orienting, attention, and memory processes.

Methods: Behavioral responses and functional magnetic resonance imaging data were collected while 18 patients with schizophrenia and 18 matched healthy control subjects performed a three-stimulus auditory oddball task.

Results: Target detection by healthy participants was associated with significant activation in all 38 regions of interest embracing distributed cortical and subcortical systems. Similar reproducibility was observed in healthy participants for processing novel stimuli. Schizophrenia patients, relative to control subjects, showed diffuse cortical and subcortical hypofunctioning during target detection and novelty processing, including bilateral frontal, temporal, and parietal cortices and amygdala, thalamus, and cerebellum.

Conclusions: These data replicate and extend imaging studies of target detection in schizophrenia and present new insights regarding novelty processing in the disorder. The results are consistent with the hypothesis that schizophrenia is characterized by a widespread pathologic process affecting many cerebral areas, including cortical, subcortical, and cerebellar circuits.

Figure 1

Hemodynamic activity elicited by auditory target stimuli in 18 schizophrenia patients and 18 matched healthy control subjects. The panels illustrate the areas of activation for target processing relative to standard stimulus baseline for healthy control subjects (far left) and schizophrenia patients (middle left). Areas where schizophrenia patients exhibit diminished activity relative to control subjects are illustrated in blue color maps (middle right); regions where patients exhibit excessive activity relative to control subjects are shown in the far right panel. The threshold for the far left panel is p < .000001; left middle, p < .001; right middle, p < .001; far right, p < .05. Complete statistical results are presented in Table 1.

Figure 2

Hemodynamic activity elicited by auditory novel stimuli in 18 schizophrenia patients and 18 matched healthy control subjects. The panels illustrate of the areas of activation for target processing relative to standard stimulus baseline for healthy control subjects (far left) and schizophrenia patients (middle left). Areas where schizophrenia patients exhibit diminished activity relative to control subjects are illustrated in blue color maps (middle right); regions where patients exhibit excessive activity relative to control subjects are shown in the far right panel. The threshold for the far left panel is p < .001; left middle, p < .001; right middle, p < .001; far right, p < .05. Complete statistical results are presented in Table 2.