Facial Expression, Communication's Second Channel

It is said that we use only 10 percent of our brain at any one time. That is fortunate, because even with only 10 percent active, the brain is using 20 percent of our oxygen, 20 percent of our nutrients, and 20 percent of our blood. The brain is the only organ with four separate arteries bringing blood to it. If we used 100 percent of our brain, out bodies would be like large balloons to breath enough oxygen, and we would eat constantly to get enough nutrients to support a fully active brain. (Image shown here is modified from The Human Brain Atlas at the Michigan State University Brain Biodiversity Banks, Sudheimer DK, Winn BM, Kerndt GM, Shoaps JM, Davis KK, Fobbs AJ, Johnson JI. Radiology Department, Communications Technology Laboratory, and College of Human Medicine, Michigan State University; National Museum of Health and Medicine, Armed Forces Institute of Pathology)


The parts of brain being used turned on, are given more blood, then turned off as information moves and is processed by different parts of the brain, which then are turned on, are given more blood, then turned off. The functional MRI is able to tell the difference between oxygenated hemoglobin and hemoglobin which is not carrying oxygen. Thus, the functional MRI is able to detect which parts of the brain are active at any given instant by detecting which parts of the brain are recieving more blood.  Using the functional MRI, researchers have been able watch the areas of activity skip across sections of the brain after a face is viewed. (Face perception is mediated by a distributed cortical network. Ishai A, Schmidt CF, Boesiger P. Brain Res Bull. 2005 Sep 30;67(1-2):87-93.)

The image of the face is constructed in the visual cortex (VC) from data recieved from the eyes. The facial image is then moved to the superior lateral sulcus (SLS) and the fusiform gyrus (FG). The superior lateral sulcus very quickly extracts the emotional information from the image of the face, and mostly from the area around the eyes. The emotional information is sent to the amygdala (Amyg) where a an initial personal emotional response is generated. The emotions from the face along with the personal emotional response is sent to the prefrontal cortex (PFC) for thinking and decisions about behavior. You can feel this pathway working particularly when you have a sudden emotion reaction to some else rolling their eye. (Affective neural circuitry during facial emotion processing in pediatric bipolar disorder. Pavuluri MN, O'Connor MM, Harral E, Sweeney JA. Biol Psychiatry. 2007 Jul 15;62(2):158-67. Epub 2006 Nov 9.)

Simultaneously, the fusiform gyrus (FG) performs a more detailed topographic analysis, looking separately at the eyes and surrounding area, the mouth, and the remaining face. The topographical information also sent to the frontal lobe, to be considered with the emotional information and the words which were heard. This pathway is used when you study the face, trying to figure out what makes that face look interesting. The fusiform gyrus pathway is also used when you ask, "where do I know him from," trying to recall the name that goes with the face. (Effective connectivity within the distributed cortical network for face perception. Fairhall SL, Ishai A. Cereb Cortex. 2007 Oct;17(10):2400-6. Epub 2006 Dec 26.)

Face-to-face conversation provides a second channel of communication in addition to the spoken words. Observing facial expression gives important information about emphasis and importance in what is being said, as well as how well we are being understood. When face-to-face, we can combine the speaker's words with their emotion, adding our own emotional reaction, and determine our own reaction with words, expressions, and behaviors. Texting or messaging with Facebook or another messenger allows for more frequent communication, but does not give the emotional richness of personal contact.

Personal interaction is important in the transfer of emotions. Interacting with a person who expresses happiness can induce a happy feeling in ourselves. The superior lateral sulcus to amygdala connection allows us to feed off other people's emotions. That is why attitude is so important, why happy people are more attractive, why happy people make a class or workplace more pleasant.

Copyright 2010, Henry Doenlen, M.D. All rights reserved.