Tricking moths into revealing the computational underpinnings of sensory integration

UW Today » Science

The hawkmoth, Manduca sexta.Rob Felt/Georgia Institute of Technology

Our nervous systems are remarkable translators, channeling information from many sources and initiating appropriate behavioral responses.
But though we know how a lot about how neurons work, scientists do not fully understand how the nervous system integrates stimuli from different senses. You may smell smoke and feel heat, but how does the brain combining and interpret these different stimuli, signaling you to phone the fire department?
It turns out that insects are attractive models to investigate questions about integrating information from different sensory pathways. The hawkmoth, Manduca sexta, uses a long, trunk-like proboscis to drink up sweet nectar meals from obliging flowers. A research team led by University of Washington biology professor Tom Daniel has teased out how hawkmoths integrate signals from two sensory systems: vision and touch.
Their findings, published Oct. 24 in the Proceedings of the National Academy of Sciences, illustrate the computational basis of this integration, which may serve as a general model for insects, other animals and humans.
“Sensory integration remains one of the more interesting tasks that even simple nervous systems accomplish,” said Daniel. “From tasks like reaching in humans to nectar-feeding in insects, our challenge has been developing experimental ways to reveal the mechanisms and circuitry that underlie combined visual and mechanical sensing.”
The hawkmoth’s proboscis is longer than its body, so it can probe deep within a flower to find nectar while the hawkmoth hovers above. Even as the flower sways and blows with the wind, hawkmoths have been observed adjusting their position to track with the flower’s position.
Scientists can study tracking behavior in the laboratory using specially designed, artificial flowers constructed with their own small nectar pods. Hawkmoths respond to these pre-packaged dinners similarly to real flowers, and — if researchers …

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