Distributed activity patterns in right temporo-parietal junction underlie intent representations
During the last few years, so-called decoding approaches have been providing novel information about the neural basis of cognitive functions at a rapidly increasing pace. The strength of such machine-learning algorithms is in that they make it possible to find distributed patterns of brain activity that are associated with specific mental states and cognitive processes. Decoding studies have, for example, disclosed specific distributed replicable “signature” patterns of brain activity that represent perceptual object categories such as chairs, tables, and butterflies within specific visual cortical areas. Studies attempting to decode higher-order cognitive processes such as inferring intentions of other persons represent in many ways the next major step forward in cognitive neuroscience.
In their recent study, Dr. Koster-Hale et al. (2013) conducted four functional magnetic resonance imaging experiments in healthy volunteers and in subjects with high-functioning autism-spectrum disorder to decode brain hemodynamic response patterns that underlie mental state reasoning, i.e., hold representations of others’ beliefs and intentions. In two of the studies, the healthy and autistic subjects were reading short stories of intended vs. non-intended harms vs. neutral stories in second person, and were to indicate with button presses after each story how much blame they ought to get from none to very much. In the other two studies, short stories describing intentional harms vs. accidental harms vs. harmless actions were read in third person, and the subjects were to either make moral judgments (from “forbidden” to “permissible”) or were to provide a true/false answer to a question concerning the stories.
The authors observed that difference between accidental and intentional harmful actions in the short stories was decodable from replicable and specific patterns of hemodynamic activity within the right temporo-parietal junction. These patterns further predicted on the invididual-participant level differences in moral judgments: individuals with more distinct activity patterns between intentional and accidental harm conditions in right temporo-parietal junction exhibited stronger moral judgment of intentional harms as contrast to accidental harms. As the third major finding, the authors report that these findings are absent in their group of subjects suffering from high-functioning type of autism spectrum disorder, and indeed individuals with this diagnosis are known to make moral judgments less on the basis of intent information than neurotypical control subjects. Together, these findings very nicely demonstrate the power of decoding approach in elucidating cerebral processing that supports higher-order cognitive processes such as mental-state inference, and show the pivotal role of right temporo-parietal junction in mental-state inference.
Reference: Koster-Hale J, Saxe R, Dungan J, Young LL. Decoding moral judgments from neural representations of intentions. Proc Natl Acad Sci USA (2013) e-publication ahead of print. http://dx.doi.org/10.1073/pnas.1207992110