Modelling basal ganglia and superior colliculus in the antisaccade task

Abstract

Event Abstract Back to Event Modelling basal ganglia and superior colliculus in the antisaccade task Thomas Trappenberg1*, Masayuki Watanabe2 and Douglas Munoz2 1 Dalhousie University, Canada 2 Queen's University , Canada A major challenge for agents in a natural environment is responding to a multitude of stimuli with often conflicting demands on a response system. Many recent studies have addressed such decision processes with competitive integrator models that accumulate evidence to aid appropriate responses [M. Usher and J.L. McClelland. Psychological Review, 108, 550-592, 2001]. A good example is visual orienting. Since we can only look at a specific direction at any moment in time, a decision system must be able to make sensible choices. An important component of this decision system is the superior colliculus (SC). We have previously modelled this area with a dynamic version of a winner-takes-all (WTA) mechanism based on physiological evidence, and we have shown that this model can explain common decision patterns in a variety of behavioral paradigms [Trappenberg et al, 2001]. This included the antisaccade task that requires subjects to orient away from a visual stimulus. This simple requirement dissociates the following two theoretical saccade commands: an automatic saccade command toward the stimulus and a volitional saccade command away from the stimulus. The automatic and volitional saccade commands stimulate SC neurons encoding opposite saccade directions, which causes a response conflict. Here we analyze the consequences of such decision processes on the frequency of trials with erroneous saccades toward the stimulus . We propose a new model of the SC based on our previous model. While this model simplifies the dynamic of the SC, it captures the competition between automatic and volitional saccades in a saccade likelihood map. We investigate how the percentage of error trials varies when modulating the relative strength of inputs encoding automatic and volitional saccade commands. We then incorporate a recent model of the basal ganglia (BG) based on our single neuron recordings in monkey caudate nucleus, the input stage of the oculomotor BG [M. Watanabe and D.P. Munoz, European Journal of Neuroscience, in press, 2009]. We have identified the following three types of caudate neurons; (1) automatic neurons (ANs) encoding contralateral automatic saccade commands, (2) volitional neurons (VNs) encoding contralateral voluntary saccade commands, and (3) ipsi neurons (INs) encoding ipsilateral volitional saccade commands, which could be ideal to suppress erroneous automatic saccade commands. We hypothesized that ANs and VNs give rise to the direct pathway facilitating saccade initiation while INs give rise to the indirect pathway suppressing saccade initiation. Here we implement this BG model and integrate it with the basic SC model. We found that the BG model can facilitate the necessary modulations of the SC to produce less error saccades, in agreement with our behavioral findings. We also found that the aid of the BG can produce behavioural ranges of error saccades when the volitional signals are weaker than automatic signals, in agreement with physiological evidence [S. Everling and D.P. Munoz, The Journal of Neuroscience, January 1, 2000, 20(1):387-400]. We are currently studying how the necessary pathways in the BG can be learned through reinforcement learning. Conference: Computational and Systems Neuroscience 2010, Salt Lake City, UT, United States, 25 Feb - 2 Mar, 2010. Presentation Type: Poster Presentation Topic: Poster session I Citation: Trappenberg T, Watanabe M and Munoz D (2010). Modelling basal ganglia and superior colliculus in the antisaccade task. Front. Neurosci. Conference Abstract: Computational and Systems Neuroscience 2010. doi: 10.3389/conf.fnins.2010.03.00092 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: 20 Feb 2010; Published Online: 20 Feb 2010. * Correspondence: Thomas Trappenberg, Dalhousie University, Halifax, Canada, trappenberg@gmail.com 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 Thomas Trappenberg Masayuki Watanabe Douglas Munoz Google Thomas Trappenberg Masayuki Watanabe Douglas Munoz Google Scholar Thomas Trappenberg Masayuki Watanabe Douglas Munoz PubMed Thomas Trappenberg Masayuki Watanabe Douglas Munoz 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.