Dynamics of neuronal adaptation in macaque MT

Abstract

Event Abstract Back to Event Dynamics of neuronal adaptation in macaque MT Pascal Wallisch1* and J. Anthony Movshon1 1 University of New York , Center for Neural Science, United States Adaptation alters the sensitivity and selectivity of neuronal responses in visual thalamus and cortex, and is commonly used to probe perceptual and neuronal mechanisms. There is, however, little consistency across laboratories in the details of the design of adaptation experiments. In particular, the literature contains adaptation experiments with adapting periods as brief as 0.25 s and as long as 60 s or more, and we wondered whether the adaptation effects revealed by these designs was the same. At a more fundamental level, the process that transduces visually evoked activity into changes in neuronal function is poorly understood, and more information about its temporal dynamics should help to uncover the underlying mechanisms. We studied adaptation in recordings from single neurons in area MT of anesthetized, paralyzed macaques by presenting drifting sinusoidal gratings of varying contrast and duration and then measuring the resulting modification of neuronal responses. We analyzed two well-known effects of adaptation: the reduction in responsiveness and the alteration of tuning properties. To determine response reduction, we measured responses to varying contrast of otherwise optimal test gratings; to determine tuning shifts, we measured direction tuning for high contrast test gratings after adapting to gratings whose direction was 30 deg displaced from the preferred direction. We confirmed previous findings that prolonged adaptation (40 s with 4 s top-ups) to high contrast targets profoundly reduced neuronal responses to contrast, and shifted neuronal tuning curves about halfway toward the direction of the adapting grating. Brief adaptation (0.25 s) to high contrast targets produced qualitatively similar but quantitatively weaker effects, on average less than one third of those of prolonged adaptation. To probe the mechanisms of short-term adaptation, we varied both the duration and the contrast of the adapting stimuli so that the product of duration and contrast was constant - i.e. we adapted at 0.5 contrast for 0.5 s, 0.25 contrast for 1 s, and so forth. Up to durations of 4 s - the longest we tested - conditions whose time-contrast product was 0.25 produced similar effects on both responsiveness and selectivity. On the other hand, adapting stimuli arranged to evoke roughly the same number of spikes produced less adaptation. We conclude that the mechanisms underlying short- and long-term adaptation are similar in their effect on neuronal properties. The changes in neuronal function are not simply due to the total spiking activity during adaptation, but instead seem to reflect the integrated visual stimulation, as captured by the time-contrast product. Conference: Bernstein Symposium 2008, Munich, Germany, 8 Oct - 10 Oct, 2008. Presentation Type: Poster Presentation Topic: All Abstracts Citation: Wallisch P and Movshon J (2008). Dynamics of neuronal adaptation in macaque MT. Front. Comput. Neurosci. Conference Abstract: Bernstein Symposium 2008. doi: 10.3389/conf.neuro.10.2008.01.093 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: 17 Nov 2008; Published Online: 17 Nov 2008. * Correspondence: Pascal Wallisch, University of New York, Center for Neural Science, New York, United States, pascal.wallisch@nyu.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 Pascal Wallisch J. Anthony Movshon Google Pascal Wallisch J. Anthony Movshon Google Scholar Pascal Wallisch J. Anthony Movshon PubMed Pascal Wallisch J. Anthony Movshon 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.