Functional MRI findings in schizophrenia

Abstract

Rather than a detailed point-by-point, article-by-article review of the existing functional MRI literature as it pertains to schizophrenia, this chapter offers a more critical perspective on assumptions made by investigators, the theoretical context in which their observations are grounded, whether the resulting conclusions stand up to criticism and the main questions that remain to be addressed by the field. These latter constitute a series of difficult but essential issues that are usually not well-articulated either in individual functional MRI reports or in reviews of the subject. For example, when functional abnormalities are documented in patients with schizophrenia, how reproducible are they from study to study? Is there any connection between brain differences that are reported in resting state studies and those that emerge from task-related paradigms? To what extent are the differences from healthy controls specific to schizophrenia patients as opposed to their unaffected relatives, or to patients with other disorders such as psychotic bipolar, schizo-affective or autism spectrum? Are they uniform in all schizophrenia patients? Are they related to symptoms? Do they occur in drug-naïve patients or are they artifacts of medication treatment? Are the abnormalities circuit-specific, or are reported findings local manifestations of a more general brain-wide process; and if so what is that process? Can it be explained physiologically, and if so at what level-the neuron, neurotransmitters, synaptic efficiency? And what are the ultimate predisposing causes such as genetically-determined neurodevelopmental anomalies? This chapter tries to cover some of these broader aspects to enable the reader to re-examine the existing literature with a more critical attitude and hopefully to think more about at what levels of inquiry the field might focus most appropriately.