3 A block design study presented simultaneous visual and auditory stimuli to first-episode neuroleptic-naïve patients. Reduced activation in parietal lobes and right thalamus and prefrontal
cortex, implicated in the dorsal visual processing pathway, was observed in patients.10 Diminished activation in patients in prefrontal regions implicated in regulating inhibition was reported in a study of the inhibitory P300 for a NoGo condition.11 A three-stimulus auditory oddball task showed diffuse cortical and subcortical hypofunction during target detection and novelty processing in schizophrenia. Individuals with prodromal Inhibitors,research,lifescience,medical symptoms demonstrated smaller differential activation in frontal regions between relevant
and irrelevant stimuli.12 In a visual oddball study, patients and healthy Inhibitors,research,lifescience,medical participants showed activation patterns specific to targets and novels, and activation of both neural systems was associated with faster performance.13 Specifically, reduced activation in regions involved in target and novelty processing in patients was accompanied by increased activation in circuits related to elaborated stimulus processing. For targets, abnormal activation was noted in regions related to ideational and visual association, and for novels Inhibitors,research,lifescience,medical patients overactivated sensory and frontal areas related to visualspatial processing and working memory ( Figure 2.) Thus, the attenuated electrophysiological response to targets seen in event-related potential studies may Inhibitors,research,lifescience,medical relate to insufficient
top-down activation of target circuitry, while the attenuated evoked response to novel distractors reflects over-processing of bottom-up events. Notably, abnormal activation in patients was associated with more severe symptoms. Figure 2. Examples of stimuli used in “oddball” studies of http://www.selleckchem.com/products/nlg919.html attentional processing (top) and contrast images of patients with schizophrenia and Inhibitors,research,lifescience,medical comparison subjects for target and novel stimuli. Greater activation in patients is depicted by the blue … Abnormal activation of frontotemporal regions has been further investigated in relation to more complex downstream processes.5,6 Verbal learning deficits are well established in schizophrenia, and fMRI studies have consistently demonstrated abnormalities during the learning phase in frontotemporal circuits. the Most studies have reported decreased activation of the frontal cortex, especially the inferior prefrontal region, in schizophrenia. The data are less consistent with regard to the temporal lobe. Most studies have observed decreased activation in patients in the hippocampus and parahippocampal gyrus, but other studies have noted increased activation. As emphasized earlier, performance may be a contributing factor as the studies differ in their approach to performance. Event-related fMRI studies have shown deficits in working memory and cognitive control in schizophrenia.