Functional magnetic resonance imaging: factors modulating the cortical activation pattern of the motor system.

The use of functional MR imaging (fMRI), especially in a clinical setting, requires knowledge and control of the physiologic factors that can affect the hemodynamic response of the brain. In this article, the authors review the influence of elementary parameters of the motor system such as hemispheric dominance, rate, and force of action, and complexity of a paradigm in determining the cortical fMRI signal change.