Neocortex

The neocortex (also known as isocortex) is a part of the brain that is responsible for higher brain functions like language and thought.

When Deanna Troi was tormented by music planted into her mind by Kevin Uxbridge, Doctor Beverly Crusher inhibited almost all the activity in her neocortex, yet the counselor continued to hear the music. 

When Captain Jean-Luc Picard was under the influence of a nucleogenic beam sent by the Kataan probe and it was attempted to interrupt the transmission, synaptic responses in his isocortex failed and the Captain nearly died before all attempts to abort the transmission were stopped. 

According to the Borg, Vulcans possess an enlarged neocortex, granting them superior analytical skills.