Faculty Directory

John G. Hildebrand

Neuroscience Regents Professor
Degrees and Appointments: 
A.B. 1964, Harvard University
PhD 1969, Rockefeller University
Research Summary: 

Functional organization and physiology of the insect olfactory system. We study the olfactory system of the giant sphinx moth Manduca sexta. Using intracellular recording and staining methods, extracellular and multi-unit recording techniques, and pharmacological manipulations, we explore the neuronal circuitry and synaptic interactions in the antennal lobe (AL), the primary olfactory center in the moth's brain. We also use histological and neuronal tracing methods to learn about the anatomical organization of the AL and its sensory inputs. Manduca sexta MothOur goal is to understand cellular mechanisms of information processing in the olfactory pathways in the CNS. Much of our work has focused on the sexually dimorphic olfactory subsystem in the male moth that is specialized to detect and process information about the female's sex pheromone. We also conduct multi-level studies of the detection and central processing of information about volatile compounds emitted by living plants. In addition to our primary focus on the AL, we are very interested in the higher-order olfactory pathways in the protocerebrum that are involved in processing of the outputs of the ALs and their integration with information of other modalities.

Behavior and chemical ecology. In parallel with our studies of the olfactory system of Manduca, we are investigating the chemical composition of the volatiles emitted by living host- and nonhost plants and using a variety of chemical, physiological and behavioral methods to identify behaviorally significant compounds in those complex mixtures. In addition, we conduct detailed studies of the effects of odors on the behavior of flying Manduca in the field and in laboratory wind tunnels.

Postembryonic, metamorphic development of the olfactory system. We have long been interested in neural development and plasticity in the ALs during the postembryonic development of Manduca. We have shown that certain, sexually dimorphic glomeruli characteristic of male and female ALs develop only if the AL is innervated, respectively, by axons of genetically male or female olfactory receptor cells. In a continuing collaboration among members of my group and faculty colleagues Leslie Tolbert, Lynne Oland, Alan Nighorn and their coworkers, a multidisciplinary quest for the cellular and molecular mechanisms underlying these and other aspects of AL development is in progress.

Organization and functions of neurosecretory systems. We have a long-standing interest in the identification, metabolism, and cellular localization of neuroeffectors (e.g. neurotransmitters, neuromodulators, neurohormones) in insects. Our current efforts focus on the functional organization of neurosecretory cells in the CNS that express neuropeptides and polypeptide neurohormones and on the roles of such cells in the control of organ function and behavior of the insect.

Publications: 

Lei H, Chiu H-Y, Hildebrand JG 2013. Responses of protocerebral neurons in male Manduca sexta to sex-pheromone mixtures. J Comp Physiol A 199:997-1014.

Martin JP, Lei H, Riffell JA, Hildebrand JG 2013. Synchronous firing of antennal-lobe projection neurons encodes the behaviorally effective ratio of sex-pheromone components in male Manduca sexta. J Comp Physiol A 199:963-979.

Riffell JA, Lei H, Abrell L, Hildebrand JG 2013. Neural basis of a pollinator's buffet: olfactory specialization and learning in the Manduca sexta moth. Science 339:200-204 Published online 6 December 2012 [DOI:10.1126/science.1225483].

Reisenman CE. Gregory T, Guerenstein PG, Hildebrand JG 2011. Feeding and defecation behavior of Triatoma rubida and its potential role as a vector of Chagas Disease in Arizona, USA. Am J Trop Med Hygiene 85:648-656.

Lei H, Reisenman CE, Wilson C, Gabbur P, Hildebrand JG 2011. Spiking patterns and their functional implications in the antennal lobe of the Tobacco Hornworm Manduca sexta. PloS One 6(8): e23382.

Martin JP, Beyerlein A, Dacks AM, Reisenman CE, Riffell JA, Lei H, Hildebrand JG 2011. The neurobiology of insect olfaction: sensory processing in a comparative context. Prog Neurobiol 95:427-447.

Tsang WM, Stone AL, Otten D, Aldworth ZN, Daniel TL, Hildebrand JG, Levine RB, Voldman J 2011. Insect-machine interface: a carbon nanotube-enhanced flexible neural probe. J Neurosci Meth 204:355-365.