Many neuroscientists found it hard to believe that a single cell could recognize an inanimate object, let alone a human being. Even objects as simple as chairs, trees, or buildings come in an almost infinite variety of forms, and the same object looks different from different perspectives or in different contexts. Neuroscientists were therefore startled in the early 1970s when experiments on monkeys by Charles Gross of Princeton turned up cells that respond selectively to hands and faces--not specific faces but faces in general.
No one had really followed up on Gross’s findings, however, until the late 1990s, when Fried and his colleagues started reporting how epileptic patients reacted to various images. Some neurons were apparently smart enough to comprehend the highly abstract concept "non-human animal." Their neurons fired when the patient was shown a picture of a tiger, eagle, antelope, and rabbit, but not when shown pictures of humans or inanimate objects. Other cells favored images only of food, or of buildings, or of human faces. Some cells responded to all faces, but others were picky, firing for male faces but not female ones, or scowling faces but not smiling ones—or, finally, faces of specific individuals.
One of the first neurons of this type was the so-called Bill Clinton cell, which was buried deep in the amygdala of a female patient. The cell responded to three very different images of the former President: a line drawing of Clinton laughing; a formal painting of him; and a photograph of him mingling with other dignitaries. The cell remained mute when the patient viewed images of other people, including male politicians and celebrities. Fried’s group found cells in other volunteers that responded in this same highly selective way to actors, including Jennifer Anniston, Brad Pitt, and Halle Berry.
One reason celebrities have played a prominent role in Fried’s experiments is that their photographs are often easier to come by than images of a patient’s own relatives. But as part of her dissertation project on biographical memory, the UCLA graduate student Viskontas has for several years been showing patients photographs of family members. Viskontas is reluctant to reveal details about her results, which have not been published yet. But she confirms that she has found neurons that respond to a particular relative: father, mother, brother, sister, grandfather, and, yes, grandmother. The experiments have also found cells that light up when a patient sees an image of himself. Call them narcissism cells.
