cerebration

from WordNet (r) 3.0 (2006)

cerebration
    n 1: the process of using your mind to consider something
         carefully; "thinking always made him frown"; "she paused
         for thought" [syn: {thinking}, {thought}, {thought
         process}, {cerebration}, {intellection}, {mentation}]

from The Collaborative International Dictionary of English v.0.48

Cerebration \Cer`e*bra"tion\, n.
   Action of the brain, whether conscious or unconscious.
   [1913 Webster]