Brains

'Brains' is a Stat that represents your intelligence and book-smarts. It can help you feint and avoid feints in combat.
Medic, Hack, Repair, Science, Linguist, Chemistry, and Teach are all skills that rely solely on Brains, checking no other stat.
The Brains stat is also used feint in combat. When your Brains stat falls below a certain point you will get a filter which can impair your speech. At 4 and below Brains, you cannot emote, instead doing random things when you try to.

Where to train

Read the wikipedia in cyberspace. Or find a certain computer deep below slagtown.

Skills that depend on Brains

Appraise
Bombs
Chemistry
Craft
Hack
Linguist
Locksmith
Medic
Persuade
Pilot
Repair
Science
Teach