The reticular activating system is a part of the brain that can be found just above where the spinal cord is connected to the brain. It is projected anteriorly to the hypothalamus to control behavior and on the posterior of the thalamus to activate awake signals.
The RAS is in charge of attention and sleep-wake cycles in humans, therefore the part of Alex's brain that was most likely activated by the sudden explosion is The reticular activating system (RAS)
The answer to this might be trauma. Such catastrophes like the 9/11 incident would not only have injuries as casualties. In the long run, effects may still show like trauma. This is caused by the psychological stress the patient has undergone on that unfortunate day.
The major major differences between membership in the senate and membership in the house come from the fact that the senate is the "higher" house and congress is the "lower" house with slightly less power.