Physics looks at the brain
Functional magnetic resonance imaging (fMRI) combines two physics-based techniques: magnetic resonance imaging (MRI) and positron emission tomography (PET). Conventional MRI offers high spatial resolution while PET shows which regions of the brain are active. fMRI can therefore be used to monitor brain activity during various tasks.
These images, taken during a recognition task, show that most areas of the brain are active after a relatively short delay of 4-6 seconds (top), whereas the anterior prefrontal regions only become active after a delay of about 8-9 seconds (bottom). (B R Rosen et al. 1998 Proc. Natl Acad. Sci. USA 95 773-780)