Abnormalities in the thalamus and prefrontal cortex during episodic object recognition in schizophrenia

Background: Many patients with schizophrenia demonstrate memory deficits. We studied patterns of brain activity during episodic recognition of new and previously seen three-dimensional objects. Methods: We used 15O positron emission tomography to study regional cerebral blood flow in eight normal subjects and nine patients with schizophrenia during a visual object recognition task. Results: In comparison with control subjects, patients with schizophrenia showed less regional cerebral blood flow increases in the pulvinar region of the right thalamus and the right prefrontal cortex during the recognition of new objects and significantly greater left prefrontal cortex regional cerebral blood flow increases during the recognition of previously seen objects. Patients with schizophrenia exhibited alarm rates to new objects similar to those of control subjects, but significantly lower recognition rates for previously seen objects. Conclusions: Schizophrenia is associated with attenuated right thalamic and right prefrontal activation during the recognition of novel visual stimuli and with increased left prefrontal cortical activation during impaired episodic recognition of previously seen visual stimuli. This study provides further evidence for abnormal thalamic and prefrontal cortex function in schizophrenia.