Final answer:
The prefrontal cortex is associated with executive functions and has been correlated with test scores and grey matter density, highlighting its role in cognitive tasks and semantic processing.
Step-by-step explanation:
The area of the brain that was correlated with test scores and grey matter density, which is also involved in executive functions, is the prefrontal cortex. Studies utilizing tools like positron emission tomography (PET) scans have shown that the prefrontal cortex is activated during tasks requiring semantic processing, such as categorizing nouns. This part of the brain is crucial for processes including memory encoding and retrieval, attention, and complex problem-solving. Another important region for memory, specifically, is the hippocampus located in the medial temporal lobe, which, along with the adjacent cortex, has been found to play a key role in the formation of new memories.
In conclusion, the prefrontal cortex is greatly implicated in executive functions necessary for cognitive tasks and higher-order processing—functions that are essential during academic testing and are reflected in test scores through the correlation with grey matter density in the brain.