The chapter deals with the neural mechanisms of praxis, that is, purposeful motor actions. Three typical praxis tasks were used: copy geometrical figures, find exit routes in mazes, and construct objects from component parts. These tasks are commonly used in clinical neurology to determine the presence, and evaluate the severity, of constructional apraxia. Brain mechanisms were investigated using various methods and in different species, including experimental psychology (in human subjects and monkeys), Functional Magnetic Resonance ImagingFunctional Magnetic Resonance Imaging (fMRI)A functional neuroimaging procedure using MRI technology that measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases.[citation needed] The primary form of fMRI uses the blood-oxygen-level dependent (BOLD) contrast, discovered by Seiji Ogawa. This is a type of specialized brain and body scan used to map neural activity in the brain or spinal cord of humans or other animals by imaging the change in blood flow (hemodynamic response) related to energy use by brain cells. Since the early 1990s, fMRI has come to dominate brain mapping research because it does not require people to undergo shots, surgery, or to ingest substances, or be exposed to ionising radiation, etc. (in human subjects), and single cell recordings from multiple sites (in monkeys). The results obtained provided new insights into how the brain deals with dynamic visuomotor processes and carries out purposeful eupractic motor actions.