gyrus (a ridge or fold on the cerebral cortex)

intracerebral; intracranial; the inside of the head / (figuratively) the inside of one's mind; within one's mind; mental (of imagined things, etc.)

(neuroanatomy) rhinencephalon

brain damage

(Internet slang) person who inflames public anxiety and/or fear with groundless information about radioactivity.

(slang) meathead; dumb muscle; someone that often uses physical strength without thinking

a cerebral lobe

(slang) endorphin or adrenaline

abovementioned item, something written at the top of a document

beheading (an instance of beheading, as punishment)