Now, a team from Carnegie Mellon University (CMU) has developed a way to accurately read more complex concepts from a brain scan, and even piece together entire sentences.

Even the most basic sentence is loaded with more information than you might realize: each word represents a new concept, and their placement and relationship to each other can drastically change the meaning of the whole. The CMU team found that the "building blocks" the mind uses to construct thoughts are made up of concepts, rather than being based on words themselves. That suggests the brain processes concepts in a universal way, regardless of a person's language and culture.

"One of the big advances of the human brain was the ability to combine individual concepts into complex thoughts, to think not just of 'bananas,' but 'I like to eat bananas in evening with my friends'," says Marcel Just, lead researcher on the study. "We have finally developed a way to see thoughts of that complexity in the fMRI signal. The discovery of this correspondence between thoughts and brain activation patterns tells us what the thoughts are built of."