Not only do autistic children often have trouble reading visual and emotional cues in conversation, but the social behaviors of their siblings may also be directly affected by the condition. Using magnetic resonance imaging (MRI), researchers at UCLA's neuroscience division determined that the brains of children with autism display significantly decreased functioning in the prefrontal cortex's mirror neuron system (MNS), a collection of neural pathways largely responsible for reading intent and emotion in the movements, tones and facial expressions of others.
In an experiment involving 16 high-functioning autistic children and 16 unaffected by the condition, faculty had each child view representations of human faces bearing different expressions meant to convey anger, happiness, etc. Half of the faces depicted were focused on the viewers themselves, while the other half gazed off in another direction. The response level of the MNS decreases when confronted by individuals whose attentions are not focused on the viewer because, for example, if the expression of the opposing individual is negative, it is seen as less threatening when not facing the other party. In the study, activity in the MNS decreased across the board when the children involved did not look directly into the eyes of the pictures facing them, but among the autistic children, the MNS was all but dormant throughout the exercise. This expected discovery goes a long way toward explaining the typical difficulties in communication and empathy experienced by so many autistic children. As the study continued, the subjects were asked to imitate the faces they saw, and the autistic children, because they had trouble discerning these expressions in the first place, scored considerably lower in their attempts to reproduce what they'd seen.
A separate study also found that the siblings of autistic children demonstrated reduced capacities for reading and reproducing emotions in third parties. The heredity of autism is well-established, and siblings of autistic children are generally rated high-risk as they run an 8% chance of developing the disorder, where its prevalence among the general population is approximately .5%. In order to measure degrees of "social referencing," or looking for the emotional cues of others to gauge one's appropriate response to a given stimuli, researchers at the University of California San Diego presented two groups of children with "ambiguous" toys, directing their caregivers to reinforce the nature of the toy in question with varied positive/negative facial and vocal signals. They were later shown images of the same toys, their brain activity measured and recorded. Not surprisingly, the group of high-risk children, though they did seek emotional cues from the adults in their presence, did so less often and read the results far less accurately. Their reactions did not correspond to those of the adults, and, again, the related areas of their brains displayed significantly less activity during the entire process.
None of the children involved in the study were diagnosed with autism after its completion, so spending large amounts of time with an autistic sibling may condition a child to these behaviors even if they are not directly affected, but its also very possible that these children have also inherited certain elements of the condition without qualifying for an actual diagnosis. The inability to properly read and apply emotion has significant implications for the development of an individual, and if the statistics observed in these two studies hold true across the population, it could mean that the number of individuals affected by autism is even higher than believed. More importantly, we now have a better idea how the brains of autistic individuals react in different ways to the same stimuli, and this knowledge will almost certainly lead to more effective treatments in the near future. At the very least, it establishes that the communication deficits experienced by autistic children are very real and spring from significant differences in the physical functions of the brain.
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