Feel guilty? That's your frontolimbic network at work! That part of your brain is responsible for the "it's all my fault" feeling:
In the 22 individuals with no family or personal history of depression that made up the control group, statements designed to induce feelings of personal blame caused brain activation in a predictable network of brain regions working together: The regions that make up the frontolimbic network -- a set of primitive structures in the brain that help us process and respond to strong emotions -- worked hand-in-glove with a structure called the anterior temporal lobe.
Melissa Healy of LA Times' Booster Shots has the story that may make you feel guilty if you skipped it: Link
Neurologically speaking, the primary site of difference is likely to be the Orbital-Frontal Cortex (OFC) as this region is implicated in the empathy-producing ability to reflect on one's own behavior relative to normativity. The OFC is listed as part of the Frontolimbic system (Review of Clinical and Functional Neuroscience - Swenson). I'd really like to read the original paper but I don't see it referenced anywhere.
When people with OFC damage perform behaviors that harm others they are typically unaware of the affect their behavior has, but when shown videos of the same behavior they succeed at making accurate moral judgments. Some researchers suggest that seeing the video strengthens the signal propagating through whatever remaining OFC tissue the patient has (most OFC patients retain some OFC tissue).
"When a person begins with a guilt experience ("Oh, look at what a horrible ???????????????????? I have ????????????????") but then magnifies and generalizes the event to the self ("and aren't I a horrible ????????????????????????"), many of the advantages of guilt are lost. Not only is a person faced with tension and remorse over a specific behavior that needs to be fixed, but he or she is also saddled with feelings of contempt and disgust for a bad, defective self. And it is the shame component of this sequence - not the guilt component - that poses the problem."
- The Handbook of Self and Identity