People who have suffered damage to their frontal cortex can sometimes literally be unable to tell the truth. This symptom is known as confabulation and differs from ordinary lying in being inherently implausible and in not being done either to secure an advantage or prevent harm. Confabulation has traditionally been thought of as a problem with memory retrieval - a mixing up of real memories with imagined facts. Researchers from the Fondazione Santa Lucia in Italy studied a 55-year-old woman who frequently confabulates following an aneurysm in the front of her brain. The women gave bizarre, innacurate answers when asked about her past experience but also made up strange answers to factual questions, invented new features when asked to copy simple line drawings and gave the origins of words when asked about their definition suggesting that her problems with confabulation were more complex than just being a memory problem.
Zannino, Gian Daniele ... [et al] - Do confabulators really try to confabulate? A case report Cognitive Neuropsychology 2008, 25(6), 831-852