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John Miller |
Contact Information
2C Lewis Hall
jpm@cns.montana.edu
(406) 994-7332
Director, Center for Computational Biology
Letters and Science Distinguished Professor
Neurophysiology
My recent experimental and theoretical studies have been focused on an analysis of the "codes" with which nerve cells in sensory systems represent information about external stimuli, the neural mechanisms through which that information is processed within subsequent stages of the nervous system, and the extent to which the nervous system may have become optimized through evolution.
On the left is an adult female cricket, with the cerci visible on the posterior of the abdomen on either side of the ovipositor, scale = 1cm. On the right is a higher magnification of the cricket’s cerci, with ovipositor removed, showing the filiform mechanosensory hairs, scale = 5mm.
My recent experimental and theoretical studies have been focused on an analysis of neural coding in the cricket cercal sensory system. The general problem has been broken down into several distinct questions related to aspects of the observed stimulus/response characteristics of the neurons: 1) What parameters of sensory stimuli are encoded in the spike trains of the receptors and first order sensory interneurons in this system? 2) What is the theoretical limiting accuracy with which those parameters could be decoded from the neuronal spike trains? 3) How is the information encoded within different aspects of the spike train patterns? 4) What are the structural and biophysical mechanisms through which the observed coding scheme is implemented within this neural network?
On the left is a computer-reconstructed image of two identified interneurons from the cricket cercal sensory system, embedded within a colored cloud that represents the density of the synaptic inputs into the system from the filiform hair mechanosensory receptor neurons on the cerci. The image on the right is a thick section through the center of the image on the left, showing the un-obscured details of some of the dendrites. A movie of a rotating reconstruction of these two interneurons in the terminal abdominal ganglion is shown below. Data for the images and movie were collected in collaboration with Dr. Gwen Jacobs.
In collaboration with Dr. Tomas Gedeon in the Department of Mathematical Sciences and Jeff Heys in the Dept. of Chemical and Biological Engineering, I am also studying the extent to which the structure and function of the cricket cercal sensory system may have been optimized, through evolution, to be more efficient from the standpoints of neural computation and sensitivity.
My general approach is to integrate electrophysiological experimental recording techniques with advanced mathematical analysis techniques toward a rigorous characterization of the neural encoding schemes. Electrophysiological approaches techniques include intracellular microelectrode recording and multi-unit extracellular recording. The major analytical techniques I have used include compartmental modeling of single identified nerve cells and a branch of multivariate statistics called "information theory."
This is a graphical summary of the major results of a functional anatomy study of the cricket cerci by Dr. Miller and his colleagues Susan Krueger, Jeff Heys and Tomas Gedeon. The two slanted panels of vectors show the combined data sets for characteristics of the filiform hairs on the three cricket cerci specimens, with all vectors color coded by the optimal stimulus direction for hair movement. The panels are rotated into the natural orientations of the cerci with respect to the cricket’s body, as if the cricket were facing upward (as indicated by the line drawing of a cricket at top center). The vector colors represent the optimal direction of air currents that would move the corresponding hair, referenced to the body axis of the cricket as defined by the circular reference legend at bottom center. The circular reference legend for vector color assignment contains an inset that presents the estimate of the entire distribution of hairs on the basal 50% of both cerci.
Selected Publications
Aldworth Z, Bender J, and Miller JP (2012). Information Transmission in Cercal Giant Interneurons is Unaffected by Axonal Conduction Noise. PLoS ONE 7(1): e30115. doi:10.1371/journal.pone.0030115
Miller JP, Krueger S, Heys J, and Gedeon T (2011). Quantitative Characterization of the Filiform Mechanosensory Hair Array on the Cricket Cercus. PLoS ONE 6(11): e27873. doi:10.1371/journal.pone.0027873
Aldworth Z, Dimitrov AG, Cummins GI, Gedeon T, and Miller JP (2011). Temporal Coding in a Nervous System. PLoS Comput Biol 7(5): e1002041. doi:10.1371/journal.pcbi.1002041
Cummins B, T.Gedeon T, Cummins G, and Miller JP (2011) Assessing the mechanical response of groups of arthropod filiform flow sensors. In Frontiers In Sensing - From Biology to Engineering, FG Barth, JAC Humphrey, MV Srinivasan (Eds.), Springer, Wien, New York.
Mulder-Rosi J, Cummins GI and Miller JP (2010) The Cricket Cercal System Implements Delay Line Processing. J. Neurophysiol. 103: 1823-1832.
Jacobs GA, Miller JP and Aldworth ZA (2008) Computational mechanisms of mechanosensory processing in the cricket. J. Exp. Biol. 211: 1819-1828.
Ogawa H, Cummins GI, Jacobs GA and Miller JP (2006) Visualization of Ensemble Activity Patterns of Mechanosensory Afferents in the Cricket Cercal Sensory System with Calcium Imaging. J. Neurobiol. 66: 293-307.
Aldworth Z, Miller JP, Gedeon T, Cummins GI & Dimitrov AG (2005). Dejittered Spike-conditioned Stimulus Waveforms Yield Improved Estimates of Neuronal Feature Selectivity and Spike-Timing Precision of Sensory Interneurons. J. Neuroscience 25(22): 5323-5332.
Huang Y and Miller JP (2004) Phased array processing for Spike Discrimination. J. Neurophysiol 92: 1944-1957.
Cummins GI, Crook SM, Dimitrov AG, Ganje T, Jacobs GA and Miller JP (2003) Structural and biophysical mechanisms underlying dynamic sensitivity of primary sensory interneurons in the cricket cercal sensory system. Neurocomputing 52: 45-52.
Dimitrov AG, Miller JP, Aldworth Z and Gedeon T (2001) Non-uniform Quantization of Neural Spike Trains through an Information Distortion Measure. Neurocomputing 38-40: 175-181.
Roddey JC, Girish B, Miller JP (2000) Assessing the performance of Neural Encoding Models in the Presence of Noise. J. Computational Neuroscience 8: 95-112.
Clague H, Theunissen FE, Miller JP (1997) The Effects of Adaptation on Neural Coding by Primary Sensory Interneurons in the Cricket cercal system. J. Neurophysiol. 77: 207-220.
Theunissen F, Roddey JC, Stufflebeam S, Clague H, Miller JP (1996) Information Theoretic analysis of dynamical encoding by four primary sensory interneurons in the cricket cercal system. J. Neurophysiol. 75: 1345-1359.
Levin J, Miller JP (1996) Stochastic resonance enhances neural encoding of broadband stimiuli in the cricket cercal sensory system. Nature 380: 165-168.
Landolfa MA, Miller JP (1995) Stimulus/response properties of cricket cercal filiform hair receptors. J. Comp. Physiol. A 177: 749-757.
Education
B.A. in Physics, University of California, Berkeley, 1972.
Ph.D. in Biology, University of Ca., San Diego, 1980. Thesis Topic: Mechanisms Underlying Pattern Generation in the Lobster Stomatogastric Ganglion. Advisor: Allen I. Selverston.
Post-Doctoral Fellowship, National Institutes of Health, Bethesda, MD, 1981, Sponsors: Wilfrid Rall and John Rinzel, Research Topic: Computational Neuroscience
Activities
Director, Center for Computational Biology
Member, Advisory Board, The Bradshaw Foundation (http://www.bradshawfoundation.com)
One of 6 founding editors, and current Action Editor, Journal of Computational Neuroscience, Kluwer, 1994-present
