Introduction

Functional magnetic resonance imaging (fMRI) is a relatively new technique for measuring changes in cerebral blood flow. The first fMRI studies, showing functional activation of the occipital cortex by visual stimulation and activation of the motor cortex by finger movement, were published in the early 1990s (12. and 3). In the few years since then, fMRI has been used to investigate the physiological response to a wide variety of experimental procedures in both normal human subjects and diverse patient groups. By 1997, there were approximately 500 sites worldwide with the capacity to perform functional MRI research. This number can be expected to increase considerably over the next 15 years. Over the same time, fMRI will probably establish a role for itself in radiological and psychiatric practice; currently the clinical role of fMRI is limited to specialized applications such as assessment of hemispheric dominance prior to neurosurgery. (4)

The outstanding advantage of fMRI over alternative methods of imaging cerebral blood flow, such as positron emission tomography ( PET) and single-photon emission computed tomography (SPECT), is that it does not involve exposure to radioactivity. This means that a single subject can safely be examined by fMRI on many occasions, and that the ethical problems of examining patients are minimized. Functional MRI also has superior spatial resolution (of the order of millimetres) and temporal resolution (of the order of seconds) compared with PET and SPECT.

In this chapter, we provide an introduction to technical issues relevant to fMRI data acquisition, study design, and analysis. An introduction to the basic physical principles of magnetization and nuclear magnetic resonance, and the technology, is given in Cb.a.9.t§I,...2,.3.7,.

Break Free From Passive Aggression

Break Free From Passive Aggression

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