Escéptico™

My mentor Norman Geschwind, the Harvard neurologist whose work bridged the classical and modern eras of brain and mind research in humans, was fond of pointing out that the reason we have difficulty smiling naturally for photographers (the “say cheese” situation) is that they ask us to control our facial muscles willfully, using the motor cortex and its pyramidal tract. (The pyramidal tract is the massive set of axons that arises in the primary motor cortex, area 4 of Brodmann, and descends to innervate the nuclei in the brain stem and spinal cord that control voluntary motion through peripheral nerves.) We thus produce, as Geschwind liked to call it, a “pyramidal smile.” We cannot mimic easily what the anterior cingulate can achieve effortlessly; we have no easy neural route to exert volitional control over the anterior cingulate. In order to smile “naturally,” you have only a few options: learn to act, or get somebody to tickle you or tell you a good joke. The career of actors and politicians hinges on this simple, annoying disposition of neurophysiology.