Receptive Field Dynamics Underlying MST Neuronal Optic Flow Selectivity

Abstract

Yu CP, Page WK, Gaborski R, Duffy CJ. Receptive field dynamics underlying MST neuronal optic flow selectivity. J Neurophysiol 103: 2794 -2807, 2010. First published March 24, 2010 doi:10.1152/jn.01085.2009. Optic flow informs moving observers about their heading direction. Neurons in monkey medial superior temporal (MST) cortex show heading selective responses to optic flow and planar direction selective responses to patches of local motion. We recorded MST neuronal responses to a 90 ϫ 90°optic flow display and to a 3 ϫ 3 array of local motion patches covering the same area. Our goal was to test the hypothesis that the optic flow responses reflect the sum of the local motion responses. The local motion responses of each neuron were modeled as mixtures of Gaussians, combining the effects of two Gaussian response functions derived using a genetic algorithm, and then used to predict that neuron's optic flow responses. Some neurons showed good correspondence between local motion models and optic flow responses, others showed substantial differences. We used the genetic algorithm to modulate the relative strength of each local motion segment's responses to accommodate interactions between segments that might modulate their relative efficacy during co-activation by global patterns of optic flow. These gain modulated models showed uniformly better fits to the optic flow responses, suggesting that coactivation of receptive field segments alters neuronal response properties. We tested this hypothesis by simultaneously presenting local motion stimuli at two different sites. These two-segment stimuli revealed that interactions between response segments have direction and location specific effects that can account for aspects of optic flow selectivity. We conclude that MST's optic flow selectivity reflects dynamic interactions between spatially distributed local planar motion response mechanisms.

Hierarchical processing of complex motion along the primate dorsal visual pathway

“…Previous MST models include those that are linear in the velocity domain (25,26) and those that derive their selectivity primarily from the spatial arrangement of MT-like inputs (11,13,14,28), as well as other more informal proposals (7,9,16). Each of these models is capable of reproducing certain qualitative aspects of the MST data, but to date there has been no statistical comparison of different model classes.…”

“…The direction, speed, and spatial response of the subunits were combined to form the response of the subunit: f ðρ; θ; pÞ ¼ p g h ∑ xy R ρðx; yÞ; p ρ · Dðθðx; yÞ; p θ Þ · G x; y; p x ; p y ; p σ : [7] Here p g denotes the gain of the subunit, and the function h(x) = max(x, 0) returns the positive part of the response (half-wave rectification). Hierarchical model with nonlinear integration.…”

“…Indeed previous studies have concluded that MST responses to complex stimuli often cannot be predicted, even qualitatively, from their responses to simple ones (7)(8)(9)16). For example, a recent paper by Yu et al (7) found that MST receptive field substructure failed to account for the response patterns of MST neurons to combinations of motions. This result led the authors to speculate that highly complex interactions must occur among MST inputs, perhaps involving specific wiring of dendritic compartments.…”

“…However, for neurons farther along the visual pathways, the relationship between stimulus input and neuronal output is often far from obvious, particularly in areas that respond to complex stimuli such as faces, objects, or optic flow patterns (4)(5)(6)(7). Uncovering this relationship is crucial for understanding the computations that underlie important behavioral functions such as object recognition and navigation.…”

Visual selectivity for heading in the macaque ventral intraparietal area

“…Two areas of the primate extrastriate and parietal cortex proved to be of specific importance in this context, i.e., the medial superior temporal area (area MST) and the ventral intraparietal area (area VIP). Neurons in area MST respond to visual and vestibular self-motion signals, and their causal role in heading perception has been confirmed Duffy 1998;Duffy andWurtz 1991a, 1991b;Gu et al 2007Gu et al , 2008Gu et al , 2010Gu et al , 2012Lappe et al 1996;Morgan et al 2008;Page and Duffy 2003;Yu et al 2010). Neurons in area VIP respond not only to visual and vestibular but also to tactile and auditory stimulation (Avillac et al 2005(Avillac et al , 2007Ben Hamed et al 2002;Bremmer et al 2002aBremmer et al , 2002bChen et al 2011b;Duhamel et al 1998;Schlack et al 2002).…”