The striatum is a structure of the brain that influences decision-making. Bending around itself like a pair of clip-on headphones, its lobe is easier to see as a rotating animation; without an animated GIF, it's hard to visualize its full shape. Damage to the striatum is linked to addiction, stereotypical behavior in animals, and other kinds of involuntary motion. Sometimes I wonder if that's what I'm reminded of when I watch The Exorcist or see fighters get knocked out in Mixed Martial Arts. When the striatum is damaged, humans seem mechanical, like they're controlled by invisible forces, like they have no say in their actions. But you probably don't feel that horror and pity when it's happening to you.
Instinct governs most of our behavior, but the so-called "executive function" is called up in certain situations to manage the brain's resources and take conscious control. According to Norman and Shallice (1980), these situations include:
- Those that involve planning or decision making.
- Those that involve error correction or troubleshooting.
- Situations where responses are not well-learned or contain novel sequences of actions.
- Dangerous or technically difficult situations.
- Situations that require the overcoming of a strong habitual response or resisting temptation.
Sometimes I think I demand too much of that little pair of headphones. It's hard to know if I'd act differently if I thought all the time about the symptoms of striatum damage. These, according to Burgess and Shallice (1996b), are:
- Inability to suppress ‘strange hypothesis’.
- Perseveration, which results in the repetition of behaviors after they have ceased to be of use.
- Inability to inhibit actions triggered by the environment.
For the third symptom, the authors give the example of a patient who is unable to pass a door without trying to open it. When I first read that paragraph, I smiled an idle smile because it reminded me of feeling compelled to open new tabs on Wikipedia.