© 2016 by Gabriella Wolff

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Photo credit: Kiley Riffell Photography

What is the neural basis of host preference in mosquitoes?

Over 3,500 mosquito species have been described in the family Culicidae, inhabiting every continent except Antarctica. Preferred hosts vary widely across mosquito species from humans and other mammals to reptiles, birds and arthropods.  Anthropophilic disease-vector mosquitoes have a significant impact on global ecosystems, epidemiology, and economies by their impact on human health and welfare, yet little is known about why they preferentially feed on humans and certain subpopulations in particular.

In order to understand why mosquitoes seek to bite their preferred hosts, I compare odor-evoked neural activity, chemoreceptivity, learning and memory behavior, and expression patterns of dopamine and serotonin in olfactory brain centers across species. 

How do insects encode olfactory memories?

In insects, olfactory information is encoded in brain structures called antennal lobes that send pathways to higher order centers. Using 2-photon calcium imaging, electrophysiology, and immunohistochemistry, we seek to understand how olfactory information is encoded into memory and how neurotransmitters such as dopamine, GABA, and serotonin modulate this circuit.

Photo credit: Kiley Riffell Photography

Did learning and memory brain structures evolve divergently?

In animals that have brains, primary sensory structures send information to higher-order processing centers in the forebrain.  Pathways from the vertebrate olfactory bulbs, for example, project to hippocampi. In insects and crustaceans, olfactory lobes send projections to higher-order centers called mushroom bodies and hemiellipsoid bodies, respectively. These centers further integrate signals encoded by pathways mediating chemosensation, vision, and mechanosensation. Evidence from insects and mammals demonstrate that these centers play crucial roles in olfactory learning and memory, exploratory behaviors, and in place memory. 

 

My research addresses the question whether these centers evolved independently across phyla or whether they may have been present in the last common ancestor of the Bilateria. Despite superficial differences in their morphology, these centers share the same neural ground pattern of nerve cell arrangements and protein expression across Arthropoda, Annelida, and Mammalia. Our studies suggest an ancestral role of mushroom body circuitry in exploratory foraging and allocentric memory.