In the past few years, one of the most significant developments in magnetic resonance imaging (MRI) is the use of MR imaging to non-invasively map human cortical function without the use of exogenous contrast agents . Since its introduction in 1992, functional magnetic resonance imaging (fMRI) has emerged as a powerful tool for studying neuronal function and generated an enormous amount of interest among neuroscientists, NMR scientists, and clinicians. The purpose of this paper is to outline the principle of fMRI and the associated technical issues and illustrate the utility of fMRI with representative applications.The basis of fMRI is the blood oxygenation level dependent (BOLD) contrast which is derived from the fact that deoxyhemoglobin is paramagnetic and changes in the local concentration of deoxyhemoglobin within the brain lead to alterations in the magnetic resonance signal. Neuronal activation within the cerebral cortex causes an increase in blood flow without a commensurate increase in oxygen extraction.
Abnormal Fractional Amplitude of Low-Frequency Fluctuation Changes in Patients with Monocular Blindness: A Functional Magnetic Resonance Imaging (MRI) Study