By LIDIA WASOWICZ
SAN FRANCISCO, Jan. 29 (UPI) -- Brain researchers searching for clues to autism have zeroed in on regions associated with recognizing and reading faces.
As early as 1947, scientific findings began hinting at neural regions that specialize in face processing. The evidence came from studies of brain-damaged patients suffering from prosopagnosia, the loss of the ability to recognize a face, and from research with macaque monkeys.
In the late 1980s, numerous studies pointed to certain "face cells" being tuned to specific facial features such as expression, identity, viewpoint or any of the component parts. Subsequent investigations showed distinct regions responding to faces, but not to cars, butterflies or other objects.
Electrical stimulation of these areas can temporarily block the ability to identify famous visages, suggesting the centers are both engaged by as well as necessary for face recognition, researchers reported in the journal Cognitive Neuropsychology.
By 1997, neuroscientists had surmised pictures of faces -- but not of objects -- activate a small patch of the brain by the right ear that, when damaged, can cause prosopagnosia. They called it the fusiform face area, although there has been some question as to whether the region is solely face-sensitive or serves a more general-purpose function.
In studies described in the Archives of General Psychiatry and other journals, researchers said they found this region buzzed with activity in non-autistic subjects -- but not in those with autism -- who were viewing pictures of faces. In the latter case, it was the neighboring regions -- usually reserved for recognizing objects -- that came to life, the scientists said.
Another team concluded people with autism see faces using different neural systems from those typically utilized in the task and that the circuitry involved is unique to each person.
"It is well known that many individuals with autism have face-processing problems," said Dr. Brad Duchaine of the Institute of Cognitive Neuroscience at the University College London.
His latest findings address the long-running debate over whether face recognition is carried out by a process specific to the task or by more generic measures that also are used for object identification.
"The results show that face recognition uses mechanisms in the brain that are different from those used in recognizing anything else," including houses, cars, horses or even people's bodies, Duchaine told United Press International.
He drew the conclusions from a brain analysis of Edward, a 53-year-old married man with a Ph.D. in theology and physics who can't tell one face from another.
"There are many theories out there about how we recognize faces and whether there is a separate social bit of the brain," Duchaine said. "So that we could draw firm conclusions to prove our facial recognition theory, we addressed all the alternatives in a single case study."
In the investigation, Edward performed as well as the test group in distinguishing between all types of objects -- from guns to guitars -- but he was stumped when it came to faces.
"Although Edward is not autistic, his results indicate that face processing is carried out by mechanisms specialized for faces, and so face processing problems in autism are also likely to be caused by problems with these mechanisms," Duchaine theorized.
"This notion is supported by the similarity between (functional magnetic resonance imaging) scans we did with Edward and those done by other labs with autistic individuals," he said.
"Unlike people with normal face recognition, Edward showed no brain areas that responded more strongly to faces than objects. Similarly, people with autism have shown a much weaker response to faces than objects."
That may be because they are not looking directly at the face, another team suggested in a study that stands to shake up the status quo.
When they do, their brains respond similarly to those of non-autistic individuals, the researchers told an annual meeting of the Society for Neuroscience in Washington.
The team reached its conclusions after poring over images of cerebral function captured as the participants viewed pictures of arrows and faces and reported the direction in which each pointed.
When looking at the non-threatening objects, the scientists said, the autistic participants showed appropriate -- though less robust than normal -- activity in portions of the frontal lobes and other brain regions where "executive" functions take place. These may include sifting through complex information, selecting the proper responses or stifling inappropriate ones.
When it came to watching faces, however, their neural networks' performance drooped, the team reported.
"This suggests that individuals with autism may be capable of simple, non-social executive tasks (say, for example, a video game), but when the task has a social component (for example, a cocktail party), it is particularly difficult for them to flexibly and appropriately respond," said lead author Aysenil Belger, associate professor of psychiatry and psychology and director of the Neuroimaging Research Department of Psychiatry at the University of North Carolina at Chapel Hill.
An intriguing question not examined by the study is whether anxiety at the prospect of a social interaction may stifle an autistic person's ability to engage in it, Belger said an interview.
The researchers also examined the activity in the "face area" of the brain.
"Faces are the quintessential social stimulus, and there is documented evidence of impaired face recognition and discrimination in autism: individuals with autism have difficulty making social-emotional judgments about faces and show reduced emotion recognition and perception from faces," Belger said.
But because they are not prosopagnosic like Edward -- that is, they can tell faces apart -- the precise nature of the deficits is unclear, scientists said.
Studies have in fact suggested enough processing occurs for autistic people to be able to distinguish faces from objects, but then they stop short of an appropriate emotional or social response to what they see, Belger said.
In his experiments, when forced to fix their gaze on a face to determine its orientation, groups with and without autism showed remarkably similar activity in the face-processing centers, including the fusiform face area, Belger said.
The finding breaks new ground, countering previous reports of under-activation of this region in people with autism, a deficit long thought to underlie their social impairment, scientists said.
Past studies failed to take into account where participants were fixing their eyes during the brain scans, the study authors said. If they were looking away from faces, as autistic people are wont to do, then, of course, the face area would not have turned on, they said.
The striking discovery suggests specific behavioral treatments may help boost the social skills of people with autism-spectrum disorders, the researchers conjectured.
If the problem lies not in eliciting a normal brain response to a face but in avoiding the face in the first place, perhaps the key is to get people with autism to make eye contact more frequently or more enduringly, scientists speculated.
If what's preventing face-to-face encounters is fear, maybe "desensitization" through increased and repeated exposure to the anxiety-arousing object, beginning early when the brain is still malleable, might do the trick, scientists reasoned.
(Note: In this multi-part installment, based on dozens of reports, conferences and interviews, Ped Med is keeping an eye on autism, taking a backward glance at its history and surrounding controversies, facing facts revealed by research and looking forward to treatment enhancements and expansions. Wasowicz is the author of the new book, "Suffer the Child: How the Healthcare System Is Failing Our Future," published by Capital Books.)
UPI Consumer Health welcomes comments on this column. E-mail: lwasowicz@upi.com
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