As Seen on House vs. the Reality of Biological Liars

In the episode Known Unknowns, Foreman explains a young woman's repeated lies. 

“She can’t control it. A bleed in her brain is affecting her thalamus, causing her to lie.”

A better description of her behavior is confabulation, the mixing of reality and fantasy, in this case to fill in gaps in memory. Bruce L. Miller, M.D., professor of neurology at the University of California at San Francisco explains it this way.

“Confabulation is making up things when you don’t know what the right answer is.”

Miller says that some patients with problems that disrupt memory may fill in the gaps with invented stories.

“We see that with a lot of neurologic diseases. We see it with a lot
of memory disorders. Alzheimer’s patients can confabulate. The classic
example where we see it is something called Korsakoff’s syndrome,
which is alcohol-related injury to the thalamus where there is a memory
disorder. These patients make up stories around what they don’t
remember."

Read the full discussion in “House, M.D. vs. Reality”