Yang and Raine et al. (2007) of the University of Southern California found that pathological liars have an increased amount of white matter in their ventral and lateral frontal lobes (this can be as much as a 36% increase in the inferior frontal cortex).
Yang and Raine et al. propose that this increase in white matter either predisposes a person towards pathological lying or is the result of the continued behavior of lying, i.e. the more you lie, the greater the amount of white matter generation in your frontal lobes.
The frontal lobe is known for executive functioning such as forecasting and predicting, and is also believed to be the association area for working memory. As lying no doubt involves a lot of frontal activity, it is not surprising that it neurologically adjusts to become better suited to the task. White matter comprises of myelinated axons that allows increased and efficient communication between brain regions. As lying is an activity that involves a lot of creativity, naturally communication between brain regions needs to be running optimally.