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Oliver Layton, N. Andrew Browning; Recurrent competition explains temporal effects of attention in MSTd. Journal of Vision 2012;12(9):935. doi: 10.1167/12.9.935.
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© ARVO (1962-2015); The Authors (2016-present)
Forward navigation in a rigid environment along straight paths without eye movements produces radial optic flow fields. A singularity called the focus of expansion (FoE) specifies the direction of travel (heading) of the observer. Cells in primate visual area MSTd are thought to be heading-sensitive, since they respond to radial fields. Humans frequently shift their focus of attention while navigating, for example, depending on the favorable or threatening context of approaching independently moving objects. Dubin & Duffy (2010, Neuroreport) showed that the spatial tuning curves of MSTd neurons change based on the relative position between an attentional prime and the FoE. Moreover, the peak mean population activity in MSTd retreated linearly in time as the distance between the attentional prime and FoE increased. We present a dynamical neural circuit model, based on the ViSTARS model (Browning et al. 2009, Cog Psy), that when given similar inputs demonstrates the linear temporal peak shift observed electrophysiologically when varying the spatial location of attention. The model also qualitatively matches the neuron tuning curves and population activation profiles. After model MT+ dynamically pools short-range motion, model MSTd incorporates recurrent competition between units tuned to different radial optic flow templates, and integrates attentional signals from model area FEF. In the model, population activity peaks indicate when the recurrent competition is most active and uncertainty is greatest about the FoE location. The nature of attention, multiplicative (Martinez-Trujillo & Treue 2004, Current Biology) or non-multiplicative (Womelsdorf et al. 2008, J. Neuroscience), is largely irrelevant, so long as attention has a Gaussian-like profile. Using particular signal functions to modulate the recurrent feedback affords qualitative fits of deflections in the population activity that otherwise appear to be low-frequency noise. We predict that these deflections mark changes in the balance of attention between the priming and FoE locations.
Meeting abstract presented at VSS 2012
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