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Competitive Dynamics in MSTd: A Mechanism for Robust Heading Perception Based on Optic Flow.

Layton OW, Fajen BR - PLoS Comput. Biol. (2016)

Bottom Line: Simulations of existing heading models that do not contain competitive dynamics yield heading estimates that are far more erratic and unstable than human judgments.Soft winner-take-all dynamics enhance units that code a heading direction consistent with the time history and suppress responses to transient changes to the optic flow field.Our findings support recurrent competitive temporal dynamics as a crucial mechanism underlying the robustness and stability of perception of heading.

View Article: PubMed Central - PubMed

Affiliation: Department of Cognitive Science, Rensselaer Polytechnic Institute, Troy, New York, United States of America.

ABSTRACT
Human heading perception based on optic flow is not only accurate, it is also remarkably robust and stable. These qualities are especially apparent when observers move through environments containing other moving objects, which introduce optic flow that is inconsistent with observer self-motion and therefore uninformative about heading direction. Moving objects may also occupy large portions of the visual field and occlude regions of the background optic flow that are most informative about heading perception. The fact that heading perception is biased by no more than a few degrees under such conditions attests to the robustness of the visual system and warrants further investigation. The aim of the present study was to investigate whether recurrent, competitive dynamics among MSTd neurons that serve to reduce uncertainty about heading over time offer a plausible mechanism for capturing the robustness of human heading perception. Simulations of existing heading models that do not contain competitive dynamics yield heading estimates that are far more erratic and unstable than human judgments. We present a dynamical model of primate visual areas V1, MT, and MSTd based on that of Layton, Mingolla, and Browning that is similar to the other models, except that the model includes recurrent interactions among model MSTd neurons. Competitive dynamics stabilize the model's heading estimate over time, even when a moving object crosses the future path. Soft winner-take-all dynamics enhance units that code a heading direction consistent with the time history and suppress responses to transient changes to the optic flow field. Our findings support recurrent competitive temporal dynamics as a crucial mechanism underlying the robustness and stability of perception of heading.

No MeSH data available.


Related in: MedlinePlus

Simulations of an approaching object that creates a radial-like flow pattern nearby the object’s trailing edge (pseudo FoE).The pseudo FoE sweeps from left to right on the left side of the visual field until it approximately coincides with the heading direction (center of the screen) at the end of the trial. The pseudo FoE dominates heading estimates in the motion pooling and differential motion models, which yield large, rapidly changing heading biases. The competitive dynamics model collects evidence about heading over time and the transient rapid sweeping of the pseudo FoE only weakly affects the heading estimate.
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pcbi.1004942.g006: Simulations of an approaching object that creates a radial-like flow pattern nearby the object’s trailing edge (pseudo FoE).The pseudo FoE sweeps from left to right on the left side of the visual field until it approximately coincides with the heading direction (center of the screen) at the end of the trial. The pseudo FoE dominates heading estimates in the motion pooling and differential motion models, which yield large, rapidly changing heading biases. The competitive dynamics model collects evidence about heading over time and the transient rapid sweeping of the pseudo FoE only weakly affects the heading estimate.

Mentions: Temporal dynamics could play an important role in the robustness and stability of heading perception in other scenarios involving moving objects. The insets at the bottom of Fig 6 depict the optic flow field generated when an approaching object crosses the observer’s path from left to right. Notice that the optical motion near the trailing edge of the object is radial-like—the motion is rightward within the object and leftward behind the trailing edge, and upward and downward above and below the horizon, respectively. Although the motion to the left and right of the trailing edge radiates from different locations (rather than from a single point as it does when there is a true focus of expansion), it may be sufficiently radial to influence neural mechanisms that are sensitive to expanding optic flow. In a previous study, we referred to the point of intersection of the trailing edge and the horizon as the pseudo FoE and found that human heading judgments are biased toward the pseudo FoE when it is present [24].


Competitive Dynamics in MSTd: A Mechanism for Robust Heading Perception Based on Optic Flow.

Layton OW, Fajen BR - PLoS Comput. Biol. (2016)

Simulations of an approaching object that creates a radial-like flow pattern nearby the object’s trailing edge (pseudo FoE).The pseudo FoE sweeps from left to right on the left side of the visual field until it approximately coincides with the heading direction (center of the screen) at the end of the trial. The pseudo FoE dominates heading estimates in the motion pooling and differential motion models, which yield large, rapidly changing heading biases. The competitive dynamics model collects evidence about heading over time and the transient rapid sweeping of the pseudo FoE only weakly affects the heading estimate.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4920404&req=5

pcbi.1004942.g006: Simulations of an approaching object that creates a radial-like flow pattern nearby the object’s trailing edge (pseudo FoE).The pseudo FoE sweeps from left to right on the left side of the visual field until it approximately coincides with the heading direction (center of the screen) at the end of the trial. The pseudo FoE dominates heading estimates in the motion pooling and differential motion models, which yield large, rapidly changing heading biases. The competitive dynamics model collects evidence about heading over time and the transient rapid sweeping of the pseudo FoE only weakly affects the heading estimate.
Mentions: Temporal dynamics could play an important role in the robustness and stability of heading perception in other scenarios involving moving objects. The insets at the bottom of Fig 6 depict the optic flow field generated when an approaching object crosses the observer’s path from left to right. Notice that the optical motion near the trailing edge of the object is radial-like—the motion is rightward within the object and leftward behind the trailing edge, and upward and downward above and below the horizon, respectively. Although the motion to the left and right of the trailing edge radiates from different locations (rather than from a single point as it does when there is a true focus of expansion), it may be sufficiently radial to influence neural mechanisms that are sensitive to expanding optic flow. In a previous study, we referred to the point of intersection of the trailing edge and the horizon as the pseudo FoE and found that human heading judgments are biased toward the pseudo FoE when it is present [24].

Bottom Line: Simulations of existing heading models that do not contain competitive dynamics yield heading estimates that are far more erratic and unstable than human judgments.Soft winner-take-all dynamics enhance units that code a heading direction consistent with the time history and suppress responses to transient changes to the optic flow field.Our findings support recurrent competitive temporal dynamics as a crucial mechanism underlying the robustness and stability of perception of heading.

View Article: PubMed Central - PubMed

Affiliation: Department of Cognitive Science, Rensselaer Polytechnic Institute, Troy, New York, United States of America.

ABSTRACT
Human heading perception based on optic flow is not only accurate, it is also remarkably robust and stable. These qualities are especially apparent when observers move through environments containing other moving objects, which introduce optic flow that is inconsistent with observer self-motion and therefore uninformative about heading direction. Moving objects may also occupy large portions of the visual field and occlude regions of the background optic flow that are most informative about heading perception. The fact that heading perception is biased by no more than a few degrees under such conditions attests to the robustness of the visual system and warrants further investigation. The aim of the present study was to investigate whether recurrent, competitive dynamics among MSTd neurons that serve to reduce uncertainty about heading over time offer a plausible mechanism for capturing the robustness of human heading perception. Simulations of existing heading models that do not contain competitive dynamics yield heading estimates that are far more erratic and unstable than human judgments. We present a dynamical model of primate visual areas V1, MT, and MSTd based on that of Layton, Mingolla, and Browning that is similar to the other models, except that the model includes recurrent interactions among model MSTd neurons. Competitive dynamics stabilize the model's heading estimate over time, even when a moving object crosses the future path. Soft winner-take-all dynamics enhance units that code a heading direction consistent with the time history and suppress responses to transient changes to the optic flow field. Our findings support recurrent competitive temporal dynamics as a crucial mechanism underlying the robustness and stability of perception of heading.

No MeSH data available.


Related in: MedlinePlus