Don't I Know You From Somewhere?

Imagine you suffer a mild seizure. You take a trip to the hospital, and luckily you’re fine. Or are you? A few days later, you leave your home to walk to the local café. You see someone walking towards you that looks oddly familiar; you stop and ask them if you know them from somewhere. You don’t. Another person, looking very familiar to you, turns a corner. Suddenly you realize that everyone around you seems to be someone you know, but you can’t remember their names or where you’ve seen them before. You have a condition called Hyperfamiliarity for Faces, or HFF.

HFF is uncommon, and typically occurs following an epileptic seizure. In most cases, there are no concurrent effects, and patients seem perfectly healthy. It is not a permanent condition, but has been shown to last anywhere from a few seconds to several years. A review by Devinsky and colleagues in 2010 pooled all available information on HFF, including case studies and data from imaging research. They point to a miscommunication between the fusiform face area and the structures involved in autobiographical and episodic memory. Lesions are typically within the left hemisphere and temporal lobe. Devinsky and colleagues also explored research on déjà vu. They view déjà vu as another form of Hyperfamiliarity, but for experiences instead of faces. Seizures stimulating the amygdala, hippocampus, and perirhinal cortex have been implicated in the déjà vu experience. There is also evidence for hyperexcitability in the right hemisphere. Perhaps, in individuals with HFF, damage to the left hemisphere requires the right hemisphere to become overactive in an attempt to restore complete functionality. Devinsky et al. summarize that “HFF may be produced by impaired left hemisphere identification of unique facial features and excessive right hemisphere processes that link individual faces with emotional and personal meaning, leading to spurious familiarity feelings. Left temporal lobe dysfunction may impair novelty signaling and detection of specific facial features while disinhibiting right temporal regions that falsely signal familiarity.”

Pretty interesting stuff! It’s hard to imagine living with HFF. What about watching a movie, or your favorite TV show? Would you get an overwhelming feeling that Angelina Jolie and Johnny Depp were pals from your past? Would the people that you actually know stand out in a sea of familiar faces? Could this be an unknown cause for uncomfortably friendly personality types (Mr. Rogers)? Thoughts to ponder!

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2848104/?tool=pmcentrez#__sec7