Prefrontal cortex: is the most anterior part of the frontal lobe in the human brain. The prefrontal cortex is critical for executive functions in humans, which includes decision making, planning, short-term memory retention, and speech production. The prefrontal cortex is thought to have developed and expanded more recently, in terms of evolution, and is larger in humans than it is in non-human primates. As such, the prefrontal cortex is thought to play a major role in the unique characteristics that make humans different from our primate ancestors.