Activation of brain reasoning areas during dreaming I would say that dreaming is like any conscious experience, except that objective reasoning is turned off. Do fMRI imaging studies indicate that the reasoning centers of the brain are inactive during REM sleep? Are other sensory sections, like the visual cortex active?

By reasoning centers of the brain, I am referring to area(s) specifically associated with logic.
I cannot answer from fMRI's, but this theory conflicts with other anecdotal evidence from medicine.

In sensory deprivation, or under psychotomimetic substances, you can be awake and unimpaired logically, and still have reality make as little sense as it does in a dream.  (People on LSD are not less logical, in an abstract sense.  If you can get them to care about an IQ test long enough to take it, they can do just as well.) 

To the extent those effects are comparable, I would doubt it is reason that is impaired.  It is more likely that reasoning is fine, but the ability to check predictions against perception is lacking.

Antonio Damasio's observations on brain lesions that limit emotion, explained in his popularizing book, seems to indicate that abstract reason needs physical grounding (from the environment or from internal sensations like emotional reactions) or it goes off the rails and does not result in what we ordinarily consider logic, even if the reasoning skills themselves are in order.

Much perceptual feedback and even internal feeback loops are disabled or attenuated by the physiological paralysis in sleep.