Neuronal circuits for auditory-olfactory integration

Abstract

The central nervous system receives information from all five senses, each of which conveys a qualitatively unique snapshot of the environment that sets it apart from the other senses. There are strong ecological benefits to such a strategy, such as when the sun sets, the visual system takes second stage to the auditory and olfactory systems, which remain fully tuned to the sounds and smells of the environment, despite the lack of visual inputs. However, in spite of this essential complementarity among the senses, the history of neuroscience research is overwhelmingly focused on understanding the mechanisms of individual sensory systems in isolation. To date, the research literature on multisensory processing pales in comparison to unimodal processing, and in the domain spanning auditory and olfactory integration, the number of original research studies on the topic are in the single digits. In our proposed project, we have designed an innovative set of experiments that will bring significant mechanistic insights to understanding how the brain synthesizes sounds and smells into cross-modal representations that can inform and enhance behavior. Across three specific aims, we will decipher the neuroanatomical circuits that support audio-olfactory integration, highlight the causal role of pivotal cross-modal brain areas in enhancing sensory thresholds and sensory acuity, and test the necessity of auditory-olfactory convergence on behavior. The work proposed here will take advantage of cutting-edge methodological tools, including the use of awake behaving mice to assess behavior; an integrated, computer controlled sound-and-smell delivery system; and optogenetic inactivation procedures to establish the mechanistic foundations by which sounds and smells can enhance stimulus processing at both the neural and behavioral levels. This work will establish the basis for a new collaboration between the Geffen and Gottfried laboratories, setting the stage for an in-depth research program that will signal a paradigm shift in how to study mechanisms of multisensory integration, not only for sounds and smells, but for combinations between all of the senses. 

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