DeFOREST MELLON, JR       

Education

• B.S. Yale University, 1957
• Ph.D. Johns Hopkins University, 1961
• Postdoctoral: Stanford University, 1961-1963

Contact Information

Research Interests

Integration of Dissimilar Senses within the Brain

The major thrust of research in my laboratory is the investigation of sensory processing in the brain, especially the integration of olfactory and hydrodynamic inputs to specialized brain regions. Animals that live within a fluid environment are exposed to odors that are dispersed both by large scale fluid movements (transvection) and by turbulent eddy currents. Fluid dynamic forces and odorants are thus inextricably combined in both the aquatic and gaseous environments. How does the brain detect, integrate and utilize these conjoined but dissimilar sensory inputs? I use the freshwater crayfish Procambarus clarkii, an animal with an excellent sense of smell, to examine the electrical and circuit properties of neurons in the olfactory lobe of the brain. These studies are revealing how flicking the antennules can enhance not only the detection of odors by sensory neurons directly exposed to the environment but how the inputs to odors and hydrodynamic stimulation co-operate within neurons of the central olfactory pathway to amplify weak odorant signals.

Figure Legend: Stacked confocal images through an olfactory lobe of the crayfish Procambarus clarkii, vibratome sections of which were challenged with an antibody against the inhibitory neurotransmitter γ-amino butyric acid (GABA) and which fluoresce in the red. A brain interneuron that responded to both odorant and hydrodynamic stimuli was injected with neurobiotin and stains with a green-fluorescing probe. The dendrites of the neuron are widely distributed within the glomeruli of the olfactory lobe, as well as in other brain regions (not shown) that receive axon terminals carrying hydrodynamic inputs. (DeF. Mellon and Barbara S. Beltz, unpublished).

Representative Publications

1. Mellon, DeF., Christison-Lagay, K.L. 2008. A mechanism for neuronal coincidence revealed in the crayfish antennule. Proc. Natl. Acad. Sci. (In press).
2. Mellon, DeF. 2007. Combining dissimilar senses: Central processing of hydrodynamic and chemosensory inputs in aquatic crustaceans. Biol. Bull. 213:1-11 (2007).
3. Mellon, DeF. and Humphrey, J.A. C. 2007. Directional asymmetry in responses of local interneurons in the crayfish deutocerebrum to hydrodynamic stimulation of the lateral antennular flagellum. J. Exp. Biol. 210:2961-2968.
4. Humphrey, J. A. C. and Mellon, DeF. 2007. Analytical and numerical investigations of the flow past the lateral antennular flagellum of the crayfish Procambarus clarkii. J. Exp. Biol. 210: 2969-2978 .
5. Mellon, DeF. 2005 Integration of hydrodynamic and odorant inputs by local interneurons of the crayfish deutocerebrum. J. Exp. Biol. 208:3711-3720.
6. Mellon, DeF. 2003. Active dendritic properties constrain input-output relationships in neurons of the central olfactory pathway in the crayfish forebrain. Micros. Res. Tech. 60:278-290.
7. Mellon, DeF. 2003. Dendritic initiation and propagation of spikes and spike bursts in a multimodal sensory interneuron: the crayfish parasol cell. J. Neurophysiol. 90:2465-2477.
8. McKinzie, M.E., Benton J.L., Beltz B.S., Mellon, DeF. 2003. Parasol cells of the hemiellipsoid body in the crayfish Procambarus clarkii: Dendritic branching patterns and functional implications. J. Comp. Neurol.
   462:168-179.

Archived Publications