The primate amygdala plays an important role in evaluating the emotional and social significance of stimuli. Our understanding of neural processes that support this role comes primarily from studies focused on vision and hearing. Using visual and auditory stimuli we learned that neurons in the amygdala respond selectively to friendly or aggressive facial expressions, to eye contact, and to social calls. Although touch can convey both positive and negative affect and can be used to build social bonds, the cellular bases of touch processing in amygdala have rarely been addressed. Recently we have identified neurons in the primate amygdala that respond to touch. The studies proposed in this application will expand on this initial finding and provide the first detailed characterization of the role of touch-sensitive neurons in the amygdala of primates.
Our first aim i s to determine the organization of tactile inputs in the amygdala.
The second aim i s to determine how subjective preference for different types of touch shapes the activity of touch-responsive neurons.
The third aim will determine the role of social partners in the subjective evaluation of touch. These studies will take advantage of species-specific value of grooming and explore the role of the primate amygdala in processing the intrinsic valence of natural social stimuli. The three specific aims are bound by a conceptual framework of the amygdala that is informed by anatomical and functional differences between the component nuclei. The simultaneous monitoring of large populations of neurons will allow testing specific hypotheses regarding the transformations that take place in each nucleus. The expected findings will allow us to place touch perception and its cellular implementation in the amygdala into the framework of social neuroscience.
The current proposal is relevant to human health because it investigates the foundations of social and affective touch. Social and affective touch are basic building blocks of human social behavior and are coordinated by a brain circuit in which the amygdala plays an important role. The amygdala is implicated in a large number of mental disorders, including mood disorders, schizophrenia, autism, and social phobia. One component of these disorders is the failure to understand social and emotional signals communicated through touch. The proposed research will determine the causal relationship between neural activity in the amygdala and the perception of basic social signals in non-human primates.