In which of the following is blood flow not increased in REM sleep?

Positron emission tomography (PET) scans of humans in REM sleep show increased activity in the pontine area, amygdala, and anterior cingulate gyrus, but decreased activity in the prefrontal and parietal coex.Activity in visual association areas is increased, but there is a decrease in the primary visual coex. This is consistent with increased emotion and operation of a closed neural system cut off from the areas that relate brain activity to the external world.