Jamie Carroll Theobald, PhD
December 2010: Theobald Lab
Department of Biological Sciences
Florida International University
Current: Research Associate, Frye Lab
Howard Hughes Medical Institute
Department of Integrative Biology and Physiology
University of California, Los Angeles
I'm especially interested in invertebrate vision, a system which offers several advantages to a researcher. Because they are small, invertebrate nervous systems are tightly constrained and highly attuned to particular behaviors. However, they are such a massively diverse group that for almost any imaginable behavior, an invertebrate can be found that performs it to perfection. Vision is a nicely tractable sensory system because the physical properties of light, such as transmission, energy, and noise level, are well-described, and the initial stages of signal processing, light capture and focus, are purely physical processes. I continue to build on my previous work studying information processing in animals. My research projects include: comparative physiology of related insects as they perform visual tasks; investigating neural circuits involved in vision in the dark; and tethered-flight behavior and free-flight path analysis during difficult visual tasks.
Comparative Visual Physiology
Nocturnal hawkmoths undertake visually demanding flights in extreme darkness. Death's head hawkmoths, (Acherontia atropos), find bee hives at night and drink honey from inside, while Elephant (Deilephila elpenor) and Tobacco hornworm (Manduca sexta) hawkmoths find flowers at night and drink nectar while hovering. How do these contrasting foraging strategies affect visual neurophysiology in these animals?
Theobald, J. C., Warrant, E. J., and O'Carroll, D. C. Wide-field motion tuning in nocturnal hawkmoths. Proceedings of the Royal Society B: Biological Sciences, 277(1683):853–860 (2010), doi:10.1098/rspb.2009.1677.
Quantitative visual psychophysics
The tethered flight arena is an extremely useful tool for visual scientists. Computer controlled Light Emitting Diode (LED) panels can display complicated visual stimuli at refresh rates relevant even to the fastest visual systems (those of flies for example). I am currently testing the fly's ability to respond to (and therefore discriminate) second-order motion as well as using white noise analysis to explore the linearity of responses to perspective corrected optic flow. (See Movies)
(Methods figure from Theobald et al., Curr Biol, 2008)
Ethology: Flight Behavior in Nature
In the field I have used perpendicular cameras, equipped with infrared (IR) light sources and sensors, to reconstruct 3-D flight paths of a bee returning to her nest after a foraging trip. (Methods figure from Theobald et al., J Exp Biol, 2007) (See Movies)
all photos © Jamie C. Theobald