About Our Research

■ Auditory System of Fruit Flies and Mosquitoes
- Genes, Neural Circuits, and Behaviors -

[Recent findings]

Even flies like a familiar song:
How auditory learning shapes
fly behavior.

We develop fruit fly model to explore how learned auditory cues alter mating behavior and sexual preference.

GABAergic interneurons regulate the fly response to the song.
We suggest that feed-forward inhibitory pathways in the fly brain adjust the behavioral response to courtship songs in female flies.
___________________________________________________________

■ Neuroanatomy-Based Systems Neurobiology in Fruit Flies

Hearing is an important sensory modality for most animals to detect sound as they mate, look for food, or fend off prey. We believe that the fruit fly, Drosophila melanogaster, is an ideal model organism for dissecting mechanisms underlying sound perception and evaluation in the brain, because of its small brain and a large variety of molecular and genetic tools available to visualize and manipulate neurons in a behaving animal. During courtship, fruit-fly males produce an acoustic signal, so-called the “love song”, which has a species-specific temporal pattern. This means that flies can discriminate sound patterns in the brain. We are trying to understand the neural mechanism how flies discriminate these acoustic signals, by establishing the comprehensive anatomical and functional map of the auditory neural circuit in the brain. So far, we have identified the primary auditory neurons and their downstream neural circuits in the brain. We have started to image the activity of these neurons and also to manipulate their activity to find a causal relationship between neurons and behaviors. We believe that our studies together are an essential path to understand the logic how the brain translates a given acoustic signal into meaningful information in a species-specific manner.

 

In the fruit fly, anatomic identification of a novel neural circuit provides a direct avenue for its functional analysis, e.g., activity imaging by expressing calcium indicator proteins, loss-of-function analysis by expressing neural toxins, and gain-of-function analysis using optogenetics or temperature-activated cation channels. Given such genetic and experimental accessibility, the antennal ear of fruit flies and its downstream neural circuits clearly constitute attractive model systems to study the fundamental aspects of sensory processing and the multimodal integration related to these mechanical signals sensed by the ear. To discover general principles underlying how the species-specific sounds are represented and evaluated within the fly brain, we are exploring the structural and functional organization of the higher-order auditory neural circuits.

 

 

■ Hearing and acoustic communication in Aedes mosquito species

Hearing is also an important sensory modality for mosquitoes. Male mosquitoes exhibit positive phonotaxis when presented with acoustic stimuli mimicking the flight tone of conspecific females. It is not yet clear exactly how sound influences female behaviour, but many researchers have suggested that females use hearing to identify suitable males during mate selection. Many mosquito species mate within male-dominated, highly circadian groups known as swarms, which offer an innovative target for control measures. We use two closely related species, the Asian tiger mosquito Aedes albopictus and the yellow fever mosquito Aedes aegypti, to investigate how acoustic stimuli influence Aedes mosquito behaviour. Both species are vectors of dengue and Zika viruses, with over half the world’s population currently at risk of infection. Improving our understanding of sound-mediated behaviours could therefore facilitate the development of new mosquito control tools, such as acoustic lures or repellents, which interfere with mosquito reproduction and thus disease transmission. Finally, recent advancements in genome editing, such as the development of CRISPR-Cas9 methodologies, have greatly facilitated the generation of mosquito mutant lines. Using these techniques, we are able investigate the underlying mechanisms of mosquito hearing by creating and testing the auditory function of hearing gene mutants. Identification of genes crucial to audition could highlight novel targets for next generation insecticides.