Neuroplasticity and Maladaptation of Sensory Systems

The theme of this GRC meeting series is "Neuroplasticity of Sensory Systems" and is focused on neuroplasticity in the auditory, visual and somatosensory systems. In this meeting series, we will endeavor to foster exchange and collaboration between scientists working at different levels, including in-vivo systems, molecular, cognitive, computational, and clinical neuroscience. By fostering exchange between investigators using different approaches, we will provide much needed opportunities for collaborations between colleagues working on related problems, and to draw inspiration, more generally, for interdisciplinary and intermodal interactions.

Over the past decades, we have gained a great deal of understanding of neuroplasticity of the brain. Sensory induced organization and re-organization happens at every level in the processing hierarchy, from subcortical pathways to primary and associative cortices. It is mediated by both ascending and descending (top-down) pathways. And it manifests in modifications at molecular, synaptic, circuit, and behavioral/cognitive levels. We shall discuss neuroplasticity in terms of homeostatic to experience-dependent mechanisms and from unimodal to cross-modal interactions.

The field has progressed sufficiently that avenues to translational applications are emerging, which we also intend to showcase by highlighting the role of neuroplasticity in of disorders of the nervous system, either in terms of pathological causes or as a potential pathway for treatment. Neuroplasticity plays an important role in shaping sensory systems, during ongoing neural processing, development, and response to injury. Understanding these processes will be important for investigations of adaptation to sensory environments, development of sensory prostheses, as well as maladaptive plasticity in disorders such as tinnitus, chronic/phantom pain, or amblyopia.

Tinnitus in the auditory domain will form one of the topics. Chronic tinnitus affects about 10-15% of the population, and is often triggered by hearing loss. There are no effective medications, nor scientifically-validated cures for most types of tinnitus. Analogous to tinnitus, phantom pain is an unpleasant phantom sensation which occurs in the absence of external stimuli in the somatosensory domain. Phantom pain has also been compared to other forms of chronic pain. There is evidence that tinnitus and phantom pain are the result of maladaptive neuroplastic changes, and both have been linked to activation of the limbic system. In both these pathologies, plastic changes of the thalamocortical projection pathway are also thought to play a role, which is why we propose to schedule sessions focusing on fundamental neuroplasticity research in both limbic and thalamocortical circuits, which may help shed light on the common underpinnings of these conditions. We aim to contrast these two plasticity disorders against another in the visual system: amblyopia, or "lazy eye". In amblyopia, a perfectly healthy eye fails to develop normal connections to visual cortex during an early sensitive period of brain development. To restore functional vision in an amblyopic eye, it is therefore necessary to facilitate and enhance plasticity of the adult visual system. The final topic will be sensory prostheses and their links to neuroplasticity. Sensory prostheses provide solutions to a number of diseases and conditions related to neuroplasticity. Cochlear implants are an established success story in the auditory system, but still need further improvement for the perception of speech and music. Crossmodal plasticity has been exploited for sensory substitution devices in the blind, as other sensory systems take over functions of the deprived visual cortex. It is widely recognized that the area needs a better understanding of neuroplasticity, and the usefulness of these devices often depends largely on the brain's ability to adapt and learn how to make the most of these technologies.