Pain insensitive structure in brain is?

Pain insensitive structure in brain is ?

Choroid plexus

Brain parenchyma

Parenchyma ,ependyma, piamatter,archanoid matter,choroid plexus

Remember with mnemonic BEDPAC
B brain parenchyma
E ependyma
D dura
P pia
A arachnoid
C choroid plexus