Tomorrow night (Friday, February 6, 2015) I will introduce a classic film, Obsession (1976), directed by Brain De Palma, for the Rubin Museum's (@RubinMuseum) Cabaret Cinema event (9:30 pm). Tim McHenry (Rubin’s Director of Public Programs and Performance; @TimMcHenryRubin) asked me to attend the viewing and to give a neuroscientific perspective on what obsession is in the brain. For those of you who cannot come, here are the main points.

First, we don't exactly know what obsession is. One piece of the puzzle is that obsession is related to the brain's reward system, which is thought to be made up of two components controlling how we “want” things and how we “like” things. Wanting is the motivation to seek reward whereas liking is the pleasure derived from getting the reward itself. In this sense, obsession is a malfunction of wanting: unstoppable motivation run amok. An example of a malfunction of liking would be anhedonia: the inability to enjoy pleasure, which can be a component of clinical depression.

The brain regions underlying motivation and pleasure are directly interconnected in a loop that we neurophysiologists refer to as a circuit. Whereas activation of this circuit can feel good in normal function, certain drugs, or diseases (like obsessive compulsive disorder; OCD) leave you wanting for more. Much much more.

Two parts of the brain that are (at least partially) responsible for motivation (identifying and seeking reward). The first is the region directly above your eyes, called the Orbital Pre-Frontal Cortex (OFC). Its connectivity counterpart, the Nucleus Accumbens (NAc), is activated when you feel pleasure.

The movie Obsession is a thriller homage to Alfred Hitchcock’s Vertigo. The plot is well conceived and hard to predict, and worth the time to watch it. Your NAc will thank you appropriately if you do.

Whereas we do not know exactly how OFC-NAc activity relates to day-to-day motivations and run-of-the-mill obsessions (like your stamp collection), or even to the heightened obsessive behavior demonstrated by the characters in De Palma’s film, research has shown that disrupting this circuit improves the symptoms of OCD. This has become the basis of a neurosurgical treatment for OCD called deep-brain-stimulation (DBS), in which electrodes are descended into the bundle of neuronal wiring that connects NAc and OFC to overstimulate it, thereby disrupting any errant and unwanted motivations—for example the pathological motivation to wash your hands 100 times every day.

I don’t think the characters in De Palma’s movie have OCD per se, but they may well be suffering from neurotraumatic sequelae that explain their unhappy behavior. Your job as a viewer will be to become an armchair psychiatrist and join us tomorrow night to diagnose the character(s) that are obsessed. Imagine what is happening in each character’s brain, and the basis for the disease.