A Biophysical Model for Neural ‘Delay-and-Correlate’

Abstract

Event Abstract Back to Event A Biophysical Model for Neural ‘Delay-and-Correlate’ Patrick A. Shoemaker1* 1 Tanner Research, Inc., United States The Hassenstein-Reichardt (1956) model for visual motion detection in insects has been influential for decades, but the identities of the neurons associated with its 'delay-and-correlate' operations have remained elusive − and the associated biophysical mechanisms are also unknown. A neural delay could be implemented any number of ways, but a truly conjunctive 'correlator' is more difficult to explain. The simple convergence of two signal pathways onto a single neuron may be necessary but is not sufficient to account for a multiplication-like interaction. Here I present a notional but biophysically-plausible concept for a neural ‘correlator’. In this model, two input channels interact in a target neuron, with the effectiveness of synaptic input from one channel augmented by the action of the second, which increases the incremental membrane resistance of the neuron. In a stage post-synaptic to the target neuron, the excitation that would be induced by the first input alone is nulled out. In the context of this model, I nominate NMDA receptors (NMDARs), which have been found in the insect brain including the optic lobes of Drosophila (Xia et al., 2005; Xia and Chiang, 2009), as a possible component of a neural ‘delay-and-correlate’. Although mechanisms not involving NMDARs may be conceived for both a delay, and a ‘correlate’ operation consistent with the model framework, I show that: 1) NMDAR kinetics are at least roughly consistent with the delay in an insect elementary motion detector; 2) the nonlinear electrical characteristics of NMDAR channels provide an intrinsic, direct means to modulate membrane resistance in the manner required for ‘correlation’. Furthermore, NMDARs are subject to neuromodulation (see, e.g., Yamakura and Shimoji, 1999), providing a mechanism for behaviorally-dependent modulation of motion detection. While these ideas are speculative, they generate hypotheses amenable to testing with current neuropharmacological and genetic techniques. Acknowledgements This work has been supported by US Air Force Office of Scientific Research Grant FA9550-12-1-0034 References Hassenstein, B., and Reichardt, W. (1956) Systemtheoretische analyse der Zeit-, Reihenfolgen-, und Vorseichenauswertung bei der Berwegungsperzeption des Rüsselkäfers Chlorophanus. Zeitschrift für Naturforschung 11b, 513-524. Xia, S., Miyashita, T., Fu, T.-S., Lin, W.-L., Wu, C.L., Pyzocha, L., Lin, I.R., Saitoe, M., Tully, T., and Chiang, A.-S. (2005) NMDA receptors mediate learning and memory in Drosophila. Current Biology 15, 603-615. Xia, S., and Chiang, A.-S. (2009) NMDA receptors in Drosophila. Ch. 10 in Biology of the NMDA Receptor, ed. A.M. van Dongen (Boca Raton, FL: CRC Press). Yamakura, T., and Shimoji, K. (1999) Subunit- and site-specific pharmacology of the NMDA receptor channel. Progress in Neurobiology 59, 279-98. Keywords: insect vision, elementary motion detector, delay and correlate, biophysical models, NMDA receptors, Neuromodulation Conference: International Conference on Invertebrate Vision, Fjälkinge, Sweden, 1 Aug - 8 Aug, 2013. Presentation Type: Poster presentation preferred Topic: Motion vision Citation: Shoemaker PA (2019). A Biophysical Model for Neural ‘Delay-and-Correlate’. Front. Physiol. Conference Abstract: International Conference on Invertebrate Vision. doi: 10.3389/conf.fphys.2013.25.00087 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 23 Apr 2013; Published Online: 09 Dec 2019. * Correspondence: Dr. Patrick A Shoemaker, Tanner Research, Inc., Monrovia, California, 91016, United States, pshoemaker@sdsu.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Patrick A Shoemaker Google Patrick A Shoemaker Google Scholar Patrick A Shoemaker PubMed Patrick A Shoemaker Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.