Final answer:
The functional magnetic resonance imaging (fMRI) measures brain activity across all tissues by mapping active areas during tasks, providing a detailed and whole-body perspective of function.
Step-by-step explanation:
To measure activity across all tissues rather than localized information, techniques like the functional magnetic resonance imaging (fMRI) are employed. For instance, during a visual task where subjects discern photographs, multiple brain areas are activated like visual sensory areas, integrating areas, and motor areas for eye movement and button pressing.
The fMRI can map these active areas in three dimensions, tracking increased blood flow associated with neuronal activity, hence providing a detailed overview of brain function during the task.
This method, which is distinct from standard MRI, assesses changes in tissue over time with a particular condition or event, offering a whole-body analysis of function. In medical practice, understanding metabolic products or reactants can also give an indirect measure of live cell activity, important for gaining insights into a person's overall health.