Final answer:
The technique that does not provide information about the activity of brain regions is PET (Positron Emission Tomography).
Step-by-step explanation:
PET scans create pictures of the living, active brain by monitoring the movement of a mildly radioactive substance called a tracer in the bloodstream. As a brain area becomes more active, more blood flows to that area. However, PET scans show little detail, are unable to pinpoint events precisely in time, and require exposure to radiation. The fMRI (Functional Magnetic Resonance Imaging) technique has replaced PET as an alternative diagnostic tool.