|A great portion of the mammalian brain is devoted to sampling and processing sensory information generated by the animal's active exploration of its surrounding environment. These complex and vital tasks are accomplished by the cooperative action of large ensembles of neurons distributed across multiple intermediary levels of the parallel sensory pathways that connect peripheral receptors to the cortical mantle. Dr. Nicolelis' laboratory is particularly interested in understanding the general computational principles underlying the dynamic interactions between populations of cortical and subcortical neurons that mediate tactile perception. To pursue this goal, Dr. Nicolelis and his colleagues have developed new electrophysiological techniques for carrying out long-term simultaneous recordings of the extracellular activity of up to 128 single neurons distributed across multiple levels of somatosensory and motor pathways in behaving animals. This experimental paradigm is used in combination with multivariate statistical techniques, computer graphics, and neural network models to analyze the spatiotemporal structure of neuronal ensemble activity and its correlation with different aspects of exploratory tactile behaviors.
Heretofore, this approach has been used to describe the spatiotemporal structure of normal sensory responses and functional plastic rearrangements within the somatosensory thalamus. Currently, the lab is investigating the dynamic interactions between populations of sensory and motor neurons during active tactile exploration of novel objects. The rat whisker system is the main model used in this investigation. Using the same experimental approach, the lab will also study haptic discrimination in behaving non-human primates. The overall goal is to verify whether patterns of neuronal ensemble activity across the sensory system predict object attributes such as shape and texture. Another main project in the lab focuses on the role of early postnatal motor activity in shaping the spatiotemporal structure of sensory responses across the rat somatosensory system.