RUI: Computational Modeling of High Level Cortical Motion Processing

Wellesley College, Wellesley Hills MA

Investigators

Abstract

A person moving through the world must judge his or her own path of motion and the three dimensional layout of the scene and identify moving objects in the scene. For example, to reach a desired destination and avoid collisions, a driver on a busy street must be able to keep the car in its lane, judge the motion of other cars and pedestrians and judge where other objects in the scene are located. All of these judgments can be made based on the motion of the visual images that are focused on the retina. Experiments show that people are remarkably adept at accomplishing these tasks, which implies that there must be neural mechanisms that compute observer motion, scene layout and the presence of moving objects. In this set of studies a computational model of this neural processing will be developed in order to investigate the underlying neural processes that compute these motion properties. The model will be based on current knowledge of how individual neurons in the Middle Temporal area (MT) of the visual cortex respond to visual motion. The MT area is known to have many neurons that respond well to motion. The purpose of building such a computational model is two-fold. First, it will show how neurons in visual cortex may calculate the direction of observer motion and the relative depth of surfaces and how they identify and locate moving objects in the scene during observer motion. In addition, the model should generate clear, testable predictions about the expected behavior of neurons that use motion in the image to compute information about the scene. These predictions will lead to additional experiments that will further extend our knowledge of these neurons. The computational model will be evaluated by running simulations that examine its ability to compute the direction of observer motion, the scene layout and the location of moving objects. The results of the simulations will show whether the model performs as well as human observers and whether the output of the model replicates the behavior of human observers during experimental testing. Further tests will examine whether the computational units in the model behave in the same way as cells in the motion processing areas of the visual cortex, such as MT and the Medial Superior Temporal area, the part of visual cortex thought to be involved in computing the direction of observer motion. The implementation and testing of this model of neural processing of visual motion will lead to increased understanding of how the brain analyzes the visual world.