. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 326 NEUROBIOLOGY AND BIOPHYSICS Properties of Medullary Interneurons of the Skate Electrosense Provide Evidence for the Neural Circuitry Mediating Ventilatory Noise Suppression John Montgomery and David Bod-nick (Wesleyan University) Afferent electrosensory fibers in elasmobranchs are strongly driven by electrical potentials produced by the animal's own ventilation (1,2). This reafference generated by movement can be considered a form of noise which ought to be removed at an early stage of sensory processing. The dorsal octa
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 326 NEUROBIOLOGY AND BIOPHYSICS Properties of Medullary Interneurons of the Skate Electrosense Provide Evidence for the Neural Circuitry Mediating Ventilatory Noise Suppression John Montgomery and David Bod-nick (Wesleyan University) Afferent electrosensory fibers in elasmobranchs are strongly driven by electrical potentials produced by the animal's own ventilation (1,2). This reafference generated by movement can be considered a form of noise which ought to be removed at an early stage of sensory processing. The dorsal octavolateralis nu- cleus (DON) is the electrosensory center in the medulla, and the ascending efferent neurons (AENs) from this nucleus do indeed show a significant reduction in ventilatory modulation without sacrificing their response to extrinsic fields. The key to under- standing the suppression of ventilatory noise is the observation that the ventilatory modulation of afferent activity is the same in all afferents, making it a "common mode" signal, which could be reduced by a subtraction of inputs from different parts of the body. Extrinsic signals are differentially represented within the afferent population and would not be suppressed by such a mechanism. The further observation, that an artificial common mode signal (produced by an electrode inserted into the gut) is also suppressed, is good evidence for the existence of a common mode suppression mechanism within the DON (3). Several lines of evidence, but principally the lack of any central neurons responding to ventilation in Platyrhinoidis (1), led to the suggestion that common mode signals could be suppressed by a collateral feedback pathway between AENs (Fig. 1A), and the feasibility of such a mechanism was confirmed by modeling studies (4). Common mode suppression could also be achieved by an alternative and simpler mechanism: inhibitory interneu- rons onto AENs could be activated directly by afferent input
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
