Research
Neuroethology
Broadly, I am interested in the mechanisms with which sensory information and information about internal physiological state are integrated to make decisions about behavior. My lab works with the nudibranch mollusc Berghia stephanieae, which has a numerically simple nervous system with individually identifiable neurons. Unlike other nudibranchs, Berghia can be raised in the lab in large numbers.
Visually guided behavior in Berghia stephanieae
Little is known about the visual capabilities of nudibranch molluscs such as Berghia stephanieae. I am characterizing visually-guided behaviors in Berghia to better understand how Berghia uses visual information to move through the environment.
Preference for dark
When placed in an arena that is half illuminated, Berghia spends more time in the dark. Behaviors in light and dark are impacted by hunger state and the presence of a food odor. Locomotor properties differ under different levels of illumination.
Approaching a visual target
Berghia reliably approaches a black stripe. This behavior is hunger state and context-dependent. Berghia is less responsive to visual targets when hungry or in the presence of a food odor. Locomotor properties differ depending on the presence of a visual target.
Eye structure
Berghia has a numerically simple eye with only 5 photoreceptors, each of which are individually identifiable. I am examining the structure of Berghia's eye using electron microscopy and the alignment and segmentation software VAST. Berghia's eye is similar to other nudibranchs.
Olfactory guided behavior
To study olfactory-guided behaviors in Berghia, I use a number of behavioral assays that allow Berghia to decide whether to approach an odor source. I use these assays to test hypotheses about the mechanisms underlying decisions to approach an odor source.
ymaze_labeled.mp4I designed a Y-maze in which water can be still or flowing. Berghia can find prey in both still and flowing water, but the mechanisms seem to differ.
In still water, we think Berghia makes comparisons of odor strength between the two rhinophores, its olfactory organs, to find prey. Berghia can no longer find food when one rhinophore is removed. In contrast, Berghia can find prey in flowing water with both rhinophores removed.