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IMAGING Brain Takes Similar Approach to Bodily, Facial Expressions When faced with the age-old conundrum, what makes us human? scientists might instinctively choose terms like rationality and logic rather than emotion. After all, those are the very qualities that science selects and nurtures. Charles Darwin, one of its most illustrious practitioners, was less biased. So acutely aware was he of the power of emotions in humans and other species that he devoted a whole book to the subject, The Expression of the Emotions in Man and Animals (1872). Neuroscientists have been rediscovering this classic text and have been imaging the human brain to see how it perceives emotional expressions. Yet these imaging studies have tended to focus exclusively on human faces. Subjects were shown pictures of actors assuming fearful (above, A) and neutral (B) body postures. Note that the faces in the images have been blurred. Fearful body images activated the same areas of the brain (below, A) as did fearful facial images (B). (Images courtesy of Nouchine Hadjikhani) "What is striking is that in everyday situations you never see a face alone unless you are watching TV," said Nouchine Hadjikhani, HMS assistant professor of radiology at Massachusetts General Hospital. "Most of the time you see people as a whole. It is kind of odd that so far people have only focused on faces because we obviously react very quickly and strongly to the bodily expression of emotion." To address this bias, Hadjikhani and her colleague Beatrice de Gelder conducted an imaging experiment to see how the brain responds to bodily expressions of fear. As they report in the Dec. 16 Current Biology, the brain reacts as quickly and with the same pair of neural structures, the amygdala and fusiform cortex, as it does in the case of facial expressions. A Brain-Body Connection On the surface, the findings might not seem surprising. After all, nature tends to be economical, using the same structures to perform related functions. Still the discovery could create a stir in the world of neuroscience. The amygdala and fusiform cortex have been so closely associated with processing facial expressions that some might argue their activation by bodily expressions of fear is really a consequence of the brain filling in an image of the face that is correspondingly fearful. Once that mental image is generated, the amygdala and fusiform cortex are activated. Yet generating a mental image takes time. In another experiment, using electrodes to record brain activity, de Gelder found that activation of the fusiform cortex in response to fearful body poses occurred too quickly to be a consequence of mental images. Resurrecting the Body Hadjikhani had more reason than most to focus on the face. As an MD, she had worked with prosopagnosia patients who, owing to brain damage or congenital defects, cannot recognize faces. But something nagged at her. "I thought, why do we always focus on faces? There is dance, there is theater, there are lots of things where people focus on bodies alone," she said. One of the big hurdles for Hadjikhani and de Gelder, who is at Tilburg University in the Netherlands, was to compile a set of body images. Facial expressions of emotion have been dissected and catalogued in minute detail by such pioneers as Paul Ekman, of the University of California, San Francisco, Medical School, and others. "There is no database of images of bodily expressions of emotion. We had to create that," Hadjikhani said. Discoveries about how the brain processes bodily expressions of fear could lead to new insights and, possibly, therapies for disorders such as autism, Williams syndrome, and Huntington's disease, said Nouchine Hadjikhani. (Photo by Graham Ramsay) De Gelder asked actors in the Netherlands to take part in a series of emotion-laden scenarios, such as being surprised by a burglar. They also performed emotionally neutral scenarios, such as pouring water into a glass. The actors were filmed and freeze frames taken. Their facial expressions were blurred so that subjects would focus only on the bodies. Hadjikhani showed the images--a block of fearful images followed by a block of neutral images--to seven subjects as they lay in a magnet at MGH. Having identified the brain's normal response to bodily emotion, the researchers plan to expand their study. "Now that we know what is happening in normals, let us study disease," said Hadjikhani. People with autism, Williams syndrome, Huntington's disease, or Parkinson's disease often have trouble recognizing or interpreting facial expressions. She would like to see whether that extends to their body expressions as well. "We are looking at this work as a potential opening to treatments and behavioral therapies," she said. --Misia Landau