Multiplicative changes in area MST neuron's responses of primate visual cortex by spatial attention

Abstract

Event Abstract Back to Event Multiplicative changes in area MST neuron's responses of primate visual cortex by spatial attention Sonia Baloni1, 2*, Daniel Kaping2 and Stefan Treue2 1 Bernstein Center for Computational Neuroscience, Germany 2 German Primate Center, Germany Spatial attention has been shown to create multiplicative enhancements of orientation tuning curves in area V4 and of direction tuning curves of area MT of primate visual cortex. We similarly, aimed to study attentional effects on tuning profiles of MST neurons, which are tuned for spiral motion space (SMS) directions. The SMS, introduced by Graziano et al. (1994), is a circular dimension that considers expansion, clockwise rotation, contraction and counterclockwise rotation as cardinal directions in this space, with a continuum of stimuli in between.We recorded SMS tuning curves from 123 MST neurons of two macaque monkeys. The monkeys were trained to attend to a target stimulus, a SMS random dot pattern (RDP) in the presence of another RDP (distractor). One of the RDP was placed in the receptive field (RF) while the other was placed outside, in the opposite hemifield. In a given trial the two RDPs moved in the same direction, picked randomly from one of twelve SMS directions and either the stimulus inside (attention-in condition) or outside (attention-out condition) the RF was the designated target. The monkeys had to report a speed change of the target stimulus while ignoring all other changes. The tuning profile of individual MST neurons can be well fitted by a Gauss function, allowing a quantitative comparison of neuronal responses to the stimulus inside the RF, when it is behaviorally relevant (attended target stimulus) or irrelevant (unattended distractor).We found that directing spatial attention into the RF enhances the response of MST neurons to optimized SMS multiplicatively (average +30%). The robust responses of MST neurons to SMS stimuli away from the preferred direction can be used to test between two alternative attentional modulation models. In the activity gain model, attention multiplicatively modulates the overall responses of neurons. Because the given activity level evoked by a particular stimulus is modulated independent of the neuron’s baseline firing rate, the given activity is multiplied by a fixed factor. An alternative to the activity gain model is the response gain model in which attention only modulates the additional activity evoked by a given stimulus leaving a neuron’s “baseline” response unmodulated.We modified the Gaussian tuning function by holding all parameters to the values obtained for the attention-out condition while introducing a single attentional multiplication factor, either multiplying the entire function (activity gain) or all parameters but the baseline (response gain). The fits are all well correlated with the data and because the two functions have a similar form they are highly correlated. A partial correlation between the fitted activity and response gain data revealed that many more cells were better fit by the activity gain model.In summary, responses in MST are multiplicatively enhanced when spatial attention is directed into the RF. This effect is best accounted for by activity gain models where the overall response of the neuron is modulated by a constant factor. Conference: Bernstein Conference on Computational Neuroscience, Frankfurt am Main, Germany, 30 Sep - 2 Oct, 2009. Presentation Type: Poster Presentation Topic: Information processing in neurons and networks Citation: Baloni S, Kaping D and Treue S (2009). Multiplicative changes in area MST neuron's responses of primate visual cortex by spatial attention. Front. Comput. Neurosci. Conference Abstract: Bernstein Conference on Computational Neuroscience. doi: 10.3389/conf.neuro.10.2009.14.045 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: 26 Aug 2009; Published Online: 26 Aug 2009. * Correspondence: Sonia Baloni, Bernstein Center for Computational Neuroscience, Göttingen, Germany, sbaloni@gwdg.de 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 Sonia Baloni Daniel Kaping Stefan Treue Google Sonia Baloni Daniel Kaping Stefan Treue Google Scholar Sonia Baloni Daniel Kaping Stefan Treue PubMed Sonia Baloni Daniel Kaping Stefan Treue 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.