BCS-Cognitive Neuroscience Initiat

With National Science Foundation support, Dr. Josephs and colleagues will conduct a three-year investigation into whether humans have a specialized brain region for letter recognition, or whether letter recognition is accomplished with the same brain regions used for recognizing other categories, like everyday objects. To test this, the researchers will use fMRI to examine brain activation patterns in human adults as they process letters or pictures of everyday objects. We hypothesize that humans recognize individual letters using the same brain regions used for object recognition, rather than using a specialized brain region dedicated solely to letter recognition. The capacity for language is often thought to set humans apart from other primates, and some scientists have suggested that the human brain has special adaptations to support language. The second goal of this project is to ask the same question about rhesus monkeys' brains. Because letters are meaningless and unfamiliar to untrained monkeys, special adaptations for letter recognition should not be detected in monkeys' brains. However, if letter-specialized regions are detected in monkeys' brains, this specialization is not likely driven by language capacity, but may instead reflect the novelty of letters to monkeys. The present proposal looks in more depth at this controversial idea of brain specialization for language by using functional magnetic resonance imaging (fMRI) to compare brain activation patterns in humans and rhesus monkeys. One challenge of this research is to determine whether monkeys are paying attention to and processing letters or objects. Like human infants, monkeys cannot express themselves through language or follow spoken or written instructions. However, both infants and monkeys will look longer at stimuli that are new, and looking time will decrease as a stimulus becomes more familiar. Therefore, by recording looking times in rhesus monkeys during fMRI scanning, Dr. Josephs and colleagues can monitor whether rhesus monkeys are paying attention to the stimuli and can distinguish different letters or objects from each other. This novel application of the looking time procedure to an fMRI environment makes comparative studies of humans and other species more feasible than currently available techniques that require months of monkey training. In addition, recording looking time minimizes the need for spoken communication or motor responses while in the MRI scanner. Therefore, this approach may be more widely applied to other special populations that cannot speak or move due to brain damage or developmental disability. The findings from this research are expected to provide important new understanding into evolution and functional organization of the human brain. In addition, several junior researchers will receive outstanding training in research experience.