Functional neuroimaging studies in humans have established that many visual cortical areas are recruited during tactile tasks. Additional methodological approaches are necessary to characterize the role of such visual cortical activity during non-visual perception and the underlying neural mechanisms. With National Science Foundation funding, this research embodies a collaboration among Drs. Krishnankutty Sathian, John Foxe, and Charles Schroeder that brings different techniques to bear on the issue of multisensory form processing in extrastriate visual cortex. Functional magnetic resonance imaging (fMRI) in humans is being combined with event-related potential (ERP) studies in humans and neurophysiologic studies in macaque monkeys, using experimental designs common to the three methods. The high spatial resolution of fMRI and the high temporal resolution of ERP studies are mutually complementary and allow specification of the temporal profile of neural activity, as well as precise localization. Monkey studies entail a combination of field potential and action potential analyses that allow both direct comparison to human (ERP/fMRI) data and investigation of the cellular bases of ERP and fMRI effects. Specific Aim I investigates the recruitment of visual cortical activity by tactile form discriminations and Specific Aim II explores multisensory interactions between vision and touch, during tactile form perception. The combination of three complementary experimental approaches being brought to bear on a common set of questions, using a common set of tasks, is unique and promises to provide a much more complete picture of the relevant neural processes than any of the approaches in isolation. This tripartite approach allows the acquisition of convergent evidence on the specific brain mechanisms of multisensory interactions, which are increasingly recognized to be ubiquitous and essential for sensory processing as well as other aspects of cognition.
Among its broader impacts, this project exemplifies the value of bringing multiple experimental approaches to bear on a set of issues. The project is anticipated to lead eventually to improvement in assistive technology available to individuals with sensory deprivation of any kind. By establishing a long-term collaboration between the three principal investigators, students and post-doctoral trainees will be able to acquire expertise in more than one of the experimental approaches, interact with more than one mentor, and further, train explicitly in the emerging field of multisensory science, a field with few formal training opportunities.