Brain blood flow changes measured by positron emission tomography during an auditory cognitive task in healthy volunteers and in schizophrenic patients.

Objective: Cognitive deficit is an essential feature of schizophrenia. One of the generally used simple cognitive tasks to characterize specific cognitive dysfunctions is the auditory "oddball" paradigm. During this task, two different tones are presented with different repetition frequencies and the subject is asked to pay attention and to respond to the less frequent tone.

[Cognitive functions in prepsychotic and negative-symptom schizophrenic patients].

Background: Relationship between schizophrenia and cognitive functions has been reported by several studies. Our work group examined the changes of cognitive functions in prepsychotic patients without any relevant psychiatric disorder in their anamnesis, and also in schizophrenic patients with predominantly negative symptoms.

Methods: Measures were carried out by Cambridge Neuropsychological Test Automated Battery (CANTAB), a complex computer-based test battery of 13 tests covering a wide range of cognitive functions.

[Auditory event related potential and PET scan: a possibility for the comprehensive evaluation of cognition].

The authors studied the parallel use of event related potential (ERP) and brain activation PET in nine healthy volunteers. The presence of P300 wave in the EEG recording was accompanied by a parallel increase in the blood perfusion of the anterior cingulate gyrus. Furthermore, the functional connectivity between cortical and subcortical structures was also present during the task.

[Use of positron emission tomography in psychiatry].

For the past years, substantial amount of experimental data has been published on the use of positron emission tomography in different psychiatric disorders. The different PET methods, which evaluate the whole-brain or regional metabolism, tissue perfusion or receptor density may help to identify the disorder specific changes in brain function and also better understand the underlying pathophysiology. In the clinical practice, PET plays an important role in the diagnosis and differential diagnosis of dementias and, presumably, in the near future the PET technique will be also extensively used in the clinical examination of other psychiatric disorders.

[Spatial standardization of [15O]-butanol PET images using T1-weighted MRI data].

Population averaged brain activation studies require the spatial standardization of the individual perfusion PET images. This procedure is usually supported by T1-weighted MRI images. The authors developed a segmentation technique to improve the automatized transformation of the individual MRI images into Talairach space.