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mechanisms of thermo- and Chemosensation and sensory behavioral plasticity

The ability to detect and respond to environmental cues is critical for animal survival. Chemosensation allows animals to find food, identify mates, and avoid predators. Thermosensation allows animals to maintain their body temperature within the physiological range and to avoid noxious heat or cold. Responses to these external cues must be both robust and flexible to allow animals to alter their behaviors as a function of not only their constantly changing environment, but also their own experience. Since defects in sensory transduction and plasticity underlie multiple neurological and behavioral disorders, it is important to understand how animals process environmental information in both development and disease.

The overall goals of this subproject are to identify the neuronal and molecular mechanisms by which C. elegans senses and responds to chemical and thermal stimuli, and to explore how these responses are altered based on experience and context. Given the strong conservation of neuron, synaptic and circuit mechanisms across species, we expect that what we learn from this work will directly influence our thinking about general principles of sensory transduction and behavioral plasticity.

Methods used: genetics, molecular biology, live imaging, in vivo calcium imaging, microfluidics, single neuron transcriptomics, high resolution behavioral assays.

Worms move robustly towards a point source of the volatile attractive odor isoamyl alcohol (video is sped up 60X). Video by Mike O'Donnell.

Levels of intracellular calcium increase in the AFD thermosensory neurons (circled in green) in animals expressing the calcium indicator G-CaMP in response to a rising temperature ramp. Note that changes in calcium dynamics are only observed as the temperature approaches 25°C, the temperature at which these animals were grown. Other fluorescent cells are expressing GFP. Movie is sped up 40X. Movie by Nathan Harris.

Work from our lab has identified molecular chemo- and thermosensors, characterized activity-dependent mechanisms that modulate sensory neuron adaptation, shown that developmental experience, as well as experiences of starvation and specific temperature regimes, modulate chemo- and thermosensory behaviors, and described underlying circuit mechanisms that drive behavioral plasticity.

Some of the questions that interest us:

  • How do chemoreceptors and thermosensors detect and transduce chemical and thermal stimuli, respectively?

  • What additional molecules play a role in maintaining the fidelity of  sensory responses?

  • How do animals retain a 'memory' of early developmental experience to alter adult sensory behaviors?

  • How does an animal's satiety state change its sensory behaviors?

  • What are the activity-dependent transcriptional and post-transcriptional changes that drive sensory behavioral plasticity?

  • How do animals integrate chemo- and thermal stimuli to drive a specific behavioral response?

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