Judges’ Queries and Presenter’s Replies

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Presentation Discussion

  • Icon for: Geoffrey Benn

    Geoffrey Benn

    Trainee
    May 23, 2012 | 11:36 p.m.

    Richard,
    Nice video – I found it quite interesting and easy to follow. Is fin proprioception is the sole means of proprioception in this type of fish? Is it possible to generate mutants deficient in fin proprioception to address this question?
    Geoff

  • May 25, 2012 | 10:35 a.m.

    Hi Geoff,

    Thank you for your question. It is unlikely that fin proprioception is the only form of proprioception that the bluegill is capable of. Other areas of the body likely provide proprioceptive feedback to optimize behaviors. Critical behaviors such as jaw opening and closing, and bending of the body wall during axial swimming at high speeds, would likely require proprioceptive sensory feedback.

    Were it possible to generate a mutant deficient in proprioceptive mechanoreceptors, it would be unlikely that one could target proprioceptors in the fin only. Mechanoreceptive mechanisms are rarely limb-specific and occur widely. A mutation which caused a lack of proprioception would be highly deleterious, making a larval preparation the most viable option for experimentation.

    Best,
    Richard

  • Icon for: Robert Full

    Robert Full

    Faculty
    May 24, 2012 | 10:39 a.m.

    Wonderful work! What approach did you use for spike analysis?

  • May 25, 2012 | 10:49 a.m.

    Hi Robert,

    Thank you very much. I am using the Wave_clus software (Rodrigo Q. Qurioga 2004; http://www.vis.caltech.edu/~rodri/Wave_clus/Wav...) for spike detection and sorting.

    Best,
    Richard

  • Further posting is closed as the competition has ended.

Icon for: Richard Williams IV

RICHARD WILLIAMS IV

University of Chicago
Years in Grad School: 5

Sensory innervation and proprioception of fish fins

While the role of pectoral fins in fish swimming has been studied in depth, little is known of how these fins receive proprioceptive feedback (sensory feedback corresponding to body position and movement). We selected the bluegill (Lepomis macrochirus), a species that uses its pectoral fins extensively during swimming, as a model organism for exploring fin proprioception. In this study we examine the responses of these nerves to sinusoidal and step-and-hold bending of the fin rays. We demonstrate that the sensory nerves innervating the pectoral fins of bluegills are capable of conveying proprioceptive feedback in response to fin bending, using extracellular physiological recordings in a fictive fin preparation. Activity recorded in response to these stimuli show that sensory nerve fibers respond to the magnitude and the velocity of the bending movement in biologically relevant ranges of actuation. Additionally, we used spike-sorting analyses to examine the responses of individual afferents to aspects of fin ray bending. These computational approaches suggest that there are multiple types of mechanosensory neurons responsive to fin ray bending and that these populations of neurons may communicate different properties of the bending stimulus. The feedback provided by these neurons may allow the pectoral fins to act as mechanical sensors as well as propulsors indicating more diverse roles for the fins than previously recognized.