I'm looking in the geck now and want to change something concerning body parts and I need to get a condition that only applies to the head.

As a function I chose getvatsvalue

Now I'm seeing two options that may mean the Head condition: Brain and Perception. Obviously I think it's brain, but I'm not sure. What is the difference?

PerceptionCondition applies to the head. Brain is only used by a couple of creatures. See the GECK entry (Perception and Brain are near the middle of the page)

http://geck.gamesas.com/index.php/Stats_List

Thank you very much for the reply, I can't believe I couldn't find it myself