Cerebral Hemispheres Last

NEUROSCIENTIFICALLY CHALLENGED

NEUROSCIENCE MADE SIMPLER

In the Eye of the Beholder

January 24, 2008


Imagine you are at work one morning, sitting at your desk (or wherever you may sit at work), and someone begins walking toward you. You look up and their face is a blur, a completely featureless void that gives you no indication who they might be. You examine their gait, their clothing, and their body shape. This tells you they are a man, but everything else is so nondescript you don’t know if he’s your boss, a visitor, or a co-worker from down the hall. You anxiously look down, hoping the person won’t notice your confusion, as it would seem quite strange since you’ve worked there for years. Only when you hear his voice do you realize he is a friend, simply interested in what you are doing for lunch.

Welcome to the world of a prosopagnosiac. People who suffer from prosopagnosia have an inability to recognize faces. The cause of the disorder, also known as face blindness, is most often some sort of brain damage, such as a tumor or lesion, but there are also congenital cases. A 2006 survey suggested that up to 2% of the population may suffer from prosopagnosia. The severity of the disorder can vary from a subtle blurring of features to the complete inability to recognize faces (even one’s own face) as described in the paragraph above. Prosopagnosiacs often learn to cope with their affliction by focusing on other features of a person that make them recognizable, such as body size, voice, or style of dress. Thus, the account above is slightly dramatized, as an inured prosopagnosiac probably would have been able to recognize a friend based on some of these other qualities before hearing his voice.

Prosopagnosia is a fascinating disorder for many reasons, but perhaps what makes it most amazing to neuroscientists is its specificity. For a long time scientists didn’t know if there were areas of the brain—or individual neurons—so specialized that, when damaged, they could impair only one distinct skill. As prosopagnosia is an example of such a case, it has contributed to our modern understanding of the brain.

Prosopagnosia appears to result from damage to an area in the temporal and occipital lobes called the fusiform gyrus. Neuroimaging studies have identified a specific region of the fusiform gyrus that is activated when a subject views a person’s face. It resultantly came to be named the fusiform face area (FFA). There has been some dispute over whether the FFA is activated only in facial recognition, but its role in seeing faces is well documented. A recent study conducted with prosopagnosiacs demonstrated that the FFA is also used when recognizing beauty in a face. While the brain is amazing for its complex interactions between its various parts, it is also interesting (and sometimes frightening) to realize just how functionally specific some of those parts are.

YOUR BRAIN, EXPLAINED

Sleep. Memory. Pleasure. Fear. Language. We experience these things every day, but how do our brains create them? Your Brain, Explained is a personal tour around your gray matter. Building on neuroscientist Marc Dingman’s popular YouTube series, 2-Minute Neuroscience, this is a friendly, engaging introduction to the human brain and its quirks using real-life examples and Dingman’s own, hand-drawn illustrations.

  • Dingman weaves classic studies with modern research into easily digestible sections, to provide an excellent primer on the rapidly advancing field of neuroscience. - Moheb Costandi, author, Neuroplasticity and 50 Human Brain Ideas You Really Need to Know

  • Reading like a collection of detective stories, Your Brain, Explained combines classic cases in the history of neurology with findings stemming from the latest techniques used to probe the brain’s secrets. - Stanley Finger, PhD, Professor Emeritus of Psychological & Brain Sciences, Washington University (St. Louis), author, Origins of Neuroscience

  • ...a highly readable and accessible introduction to the operation of the brain and current issues in neuroscience... a wonderful introduction to the field. - Frank Amthor, PhD, Professor of Psychology, The University of Alabama at Birmingham, author, Neuroscience for Dummies

  • An informative, accessible and engaging book for anyone who has even the slightest interest in how the brain works, but doesn’t know where to begin. - Dean Burnett, PhD, author, Happy Brain and Idiot Brain