Next, Kar evaluated the role of the amygdala. Better models of the brain will come along, “but oftentimes in the clinic, we don’t need to wait for the absolute best product.” If the difference between how closely the network matches neurotypical controls versus autistic adults is greater when judging one set of images versus another set of images, the first set could be used in the clinic to detect autistic behavioral traits. The other function is that the network can be used to select images that might be more efficient in autism diagnoses. Kar’s results implicate the IT cortex in differentiating neurotypical controls from autistic adults. Previous work has shown that this layer in some ways mimics the IT cortex, which sits near the end of the primate brain’s ventral visual processing pipeline. This difference was greatest when the output was based on the last network layer. He stripped off layers and retested its performance, measuring the difference between how well it matched controls and how well it matched autistic adults. The network also served two more interesting functions. Kar found that the network’s behavior more closely matched the neurotypical controls than it did the autistic adults. These layers process information as it passes from an input image to a final judgment indicating the probability that the face is happy.
The network contained layers of units that roughly resemble biological neurons that process visual information. Kar, who is also a member of the Center for Brains, Minds and Machines, trained an artificial neural network, a complex mathematical function inspired by the brain’s architecture, to perform the same task. Compared with controls, autistic adults required higher levels of happiness in the faces to report them as happy.
FACE OUTLINE SOFTWARE
The images had been generated by software to vary on a spectrum from fearful to happy, and the participants judged, quickly, whether the faces depicted happiness. In one experiment, they showed images of faces to autistic adults and to neurotypical controls. Kar began by looking at data provided by two other researchers: Shuo Wang at Washington University in St. (DiCarlo, the Peter de Florez Professor in the Department of Brain and Cognitive Sciences, is a member of the McGovern Institute for Brain Research and director of MIT's Quest for Intelligence.) Kohitij Kar, a research scientist in the lab of MIT Professor James DiCarlo, hoped to zero in on the answer. Meanwhile, a deeper region called the amygdala receives input from the IT cortex and other sources and helps process emotions. A region on the side of the primate (including human) brain called the inferior temporal (IT) cortex contributes to facial recognition. Researchers have primarily suggested two brain areas where the differences might lie. And it does so using a tool that opens new pathways to modeling the computation in our heads: artificial intelligence. But new research, published June 15 in The Journal of Neuroscience, sheds light on the inner workings of the brain to suggest an answer. Autistic people often have a more difficult time with this task. A smile may mean happiness, while a frown may indicate anger. Many of us easily recognize emotions expressed in others’ faces.
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