Interesting Facts About Brain

• Structural and functional imaging
There are several methods for detecting brain activity changes using three-dimensional imaging of local changes in blood flow. The older methods are SPECT and PET, which depend on injection of radioactive tracers into the bloodstream. A newer method, functional magnetic resonance imaging (fMRI), has considerably better spatial resolution and involves no radioactivity. Using the most powerful magnets currently available, fMRI can localize brain activity changes to regions as small as one cubic millimeter. The downside is that the temporal resolution is poor: when brain activity increases, the blood flow response is delayed by 1–5 seconds and lasts for at least 10 seconds. Thus, fMRI is a very useful tool for learning which brain regions are involved in a given behavior, but gives little information about the temporal dynamics of their responses. A major advantage for fMRI is that, because it is non-invasive, it can readily be used on human subjects.
Another new non-invasive functional imaging method is functional near-infrared spectroscopy.