The Collaborative International Dictionary of English v.0.48:

Sensorium \Sen*so"ri*um\, n.; pl. E. Sensoriums, L.
   Sensoria. [L., fr. sentire, sensum, to discern or perceive
   by the senses.] (Physiol.)
   The seat of sensation; the nervous center or centers to which
   impressions from the external world must be conveyed before
   they can be perceived; the place where external impressions
   are localized, and transformed into sensations, prior to
   being reflected to other parts of the organism; hence, the
   whole nervous system, when animated, so far as it is
   susceptible of common or special sensations.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sensorium
    n 1: the areas of the brain that process and register incoming
         sensory information and make possible the conscious
         awareness of the world