Our brain accomplished many things including perception and sensation at what level?

it's unconscious

Sensation and perception are accomplished by our brain in the unconscious level. This level describes the mental state that a person presents when they develop it without a warning of its actions, meaning without realizing he is doing it, it doesn't depend on his own voluntary to make it happen. This fits with sensation and perception because they are, respectively, the reaction of a receptor to stimulation while the other is the procedure of interpreting a stimulation.