Laboratory Address:
LS 2804 UNITED STATES
Work Address:
Office LSB 2804 UNITED STATES
LS room 2804 612 Charles E. Young Dr. South Los Angeles, CA 90095 UNITED STATES
Work Phone Number:
(310) 206-4467
(310) 825-5360
|
| ACCESS Affinity - Neurobiology |
|
How are flexible and robust animal behaviors orchestrated by the nervous system? Different forms of this general question have occupied neuroscientists for decades. Great strides have been made toward describing the basic mechanisms of nervous system development, structure, and function. Our next challenge is to examine how complex behaviors emerge from the interactions among genetic, cellular, cell-system, and organ-system levels of organization. My laboratory studies these interactions in a powerful model system � the fruit fly Drosophila melanogaster. Whereas research with Drosophila is most often focused within the molecular-genetic spectrum, this animal also shows remarkable behavioral performance; it makes its living flying vast distances through complex visual landscapes in search of the source of an attractive odor. A fly�s sophisticated navigation capabilities emerge from the fusion of visual and olfactory sensory cues and transformation of a motor code to control flight trajectory. By combining the rapidly expanding toolkit of fruit fly molecular genetics with state-of-the-art computational and behavioral analysis systems, we hope to reveal the structural circuits and functional mechanisms with which the fly brain fuses multi-sensory signals into the motor control of complex flight behavior. The results of this cross-disciplinary approach could have broad impact on our understanding of the mechanisms of sensory fusion and sensory-motor integration common among animal taxa.
We focus on three broad questions: (1) How do visual and olfactory cues influence the spatial and temporal control of free-flight trajectory? (2) How are visual and olfactory cues experienced during free flight integrated with motor output? (3) What are the anatomical loci and physiological mechanisms of sensory fusion and sensory-motor integration? To address these questions, we integrate four complimentary experimental techniques: (1) real-time three-dimensional tracking of flies in free-flight, (2) flight simulators for tethered animals operating under naturalistic visual-motor feedback conditions, (3) electrophysiological recordings from the central nervous system and flight muscles, and (4) molecular-genetics to target the expression of reporter and effector genes within the brain. Using this combination of approaches, it is possible to reconstruct the �fly�s-eye-view� during free flight, and then replay those stimuli during tethered flight to map motor responses to systematic variation of visual and olfactory cues. Quantitative analysis of flight performance under these conditions coupled with electrophysiological recordings and genetic manipulations of visual and olfactory pathways will reveal structure-function relationships for specific cell systems in the central nervous system. Through this systems-level approach we hope to overcome many of the experimental hurdles that limit the study of sensory fusion and sensory-motor integration.
Our early analyses have been very fruitful. Cross-modal integration is clearly important to freely flying Drosophila. Individual flies released in a large arena lined with a black and white random visual background faithfully localize the source of an attractive odorant emanating from the featureless floor. However, animals flown in an arena lined with a uniform white surround fail to locate the odor source (Frye et al., 2003). Our central challenge is to identify the mechanisms mediating this visual-olfactory interdependence. Flies tethered within an electronic flight simulator show different patterns of motor-driven wing kinematics in response to olfactory and visual cues. Remarkably, the flight motor output appears to reflect the linear sum of visual and olfactory sensory input, suggesting that the two modalities are, in effect, processed along parallel neural channels (Frye and Dickinson, 2004b). We are incorporating genetic approaches to map the neural circuits responsible for visual and olfactory flight control. For example, a postdoc in the lab has isolated several enhancer trap promoters localized to a poorly understood region of the visual system, the medulla. By expressing a current-shunting potassium channel, we have impaired the ability of these cells to generate action potentials. Transgenic flies were tested for their motor responses to visual motion cues. Whereas the responses to panoramic motion appear to be unaltered by the transgene, responses to object motion are attenuated. The results of these and similar experiments could have impact well beyond the domain of Drosophila neurobiology, and provide new insight into studies of sensory physiology, biomechanics, genetics, as well as the growing engineering field of biomimetics.
|
|
Dr. Frye began his research career at Union College, then received his PhD at the University of Washington. As a postdoctoral fellow at Berkeley and then at Caltech, he began to work on multi-sensory processing and motor control of flight in fruit flies. He is currently a member of the Department of Physiological Science, and teaches courses in integrative and comparative animal physiology. He is the reciepient of a Sloan Foundation Fellowship, and his laboratory examines sensory fuison and sensory-motor integration for the control of walking and flight in fruit flies.
|
Duistermars, B.J.
Reiser, M.B.
Zhu, Y.
Frye, M.A. Dynamic properties of large-field and small-field optomotor flight responses in Drosophila.
Journal of Comparative Physiology A
2007; in press:
.
Reynolds, A.
Frye, M.A. Free-flight odor tracking in Drosophila is consistent with a mathematically optimal intermittent scale-free search.
PLoS ONE
2007; 2(4):
354.
Humbert, J.S.
Frye, M.A. Extracting behaviorally relevant retinal image motion cues via wide-field integration.
Proc. IEEE American Controls Conference
2006;
2724-2729.
Frye, MA Dickinson, MH Fly flight: a model for the neural control of complex behavior..
Neuron. .
2001; 32(3):
385-8.
|
|
|
