KQED’s science programme Quest has put some completely fascinating audio and video segments online on the science of emotion and how neurological disorders can lead to almost instant laughing and crying that are not always accompanied by the strong emotions we normally associate with them.
The condition is called ‘pseudobulbar affect‘ by neurologists although virtually the same behaviour in the context of mental illness is usually called ‘labile affect’ by psychiatrists.
If you’re not familiar with the term ‘affect‘ used in this context it refers to anything to do with mood or emotion. Pseudobulbar refers to the fact that the damage can impair the control of ‘bulbar’ cranial nerves VII – XII (although the damage is not to the nerves themselves – hence the pseudo prefix) and labile simply means changeable.
One of the most difficult aspects of pseudobulbar affect is the fact that it can appear inappropriately potentially causing some awkward social situations. For example, the person in the programme, who is affected by the degenerative brain disorder ALS, describes laughing at a funeral and one video shows how easily these reactions can be triggered.
Out of place emotional reactions are not uncommon in neurological disorders. In fact, there is a type of seizure which causes laughter and has the wonderfully evocative name of gelastic epilepsy.
The other video segment is a fantastic introduction to functional neuroimaging studies of emotion. Look out for the explanation of MRI physics using Whirling Dervishes as an example of proton spin!
There’s also a fantastic audio segment specifically on researching emotion in pseudobulbar affect and how the findings might help us understand emotions in depression, obsessive compulsive disorder and PTSD.
It’s a wonderfully made piece that shows how affected people experience this rapid form of emotional weather and does a great job of communicating the scientific research. Good job KQED.
Link to video segment ‘Emotions from the Inside and Out’ (thanks Jennifer!).
Link to video segment ‘Watching the Brain at Work’.
Link to audio segment ‘Decoding the Emotional Brain’.
Link to additional online notes.
Mind Hacks 
Now that I’ve stopped crying from sharing those moments with Matt, thanks for the post, Vaughan. This is the most consistently non-boring neuro site, and the standards are high.
Personalizing images or other input as a trigger for the pseudobulbar affect is key. Doesn’t this implicate the autobiographical memory bank in the hippocampus? Convenient proximity to the amygdala in the good old medial temporal lobe.
The Quest segment centered on ALS, but let’s not overlook temporal lobe tumors, with a right or left side focus of damage – and how does the affect differ for each side? Does gender factor in here on the neuro research end? What is socially acceptable for expression of emotion in women is more strictly, and unfairly, judged inappropriate in men.
Laughing at the doctor’s office is OK: neurologists have senses of humor too.
These studies on pseudobulbar affect can give us many clues on the management of emotions in social interactions, humour, neuroculture (or the study of social norms of when and with whom we express or repress emotions), moral appropriateness or correctness (i have to confess that i feel a little bit of embarrasment because of the contagiousnes of laughs knowing that the individual who is laughing has a neurological condition that impede him to control emotions) and many other issues.
Great post! really.