Huk Lab: Research

Research in our lab focuses on how the visual system processes motion. We rely on visual motion as a model system to understand how neurons transform simple sensory signals into representations used during perception, cognition, and action. We employ a variety of psychophysical and physiological techniques to address these issues. Specifically, we focus on (1) how motion and depth information is combined to represent the 3D direction of motion, (2) how visual motion signals are accumulated and remembered to inform perceptual decisions, and (3) how visual imagery and expectations about motion interact with low-level sensory processing.

Neural Basis of the Perception of 3D Motion

The world has three spatial dimensions, not two ... and objects move through all three of these dimensions. However, the vast majority of what we know about motion processing comes from experiments in which patterns move on flat (2D) computer screens; Surprisingly little is known about how the brain combines motion and depth information to encode realistic motions through 3D space. We are performing human psychophysical and brain imaging experiments to identify how the brain combines the two-dimensional motion signals extracted from each retina to process 3D motion.

Papers on motion perception:

Rokers, B., Cormack, L.K., & Huk, A.C. (2009). Disparity- and velocity- based signals for 3D motion perception in human MT+. Nature Neuroscience, 12(8), 1050-1055. [PDF] [supplementary]

Rokers, B., Cormack, L.K., & Huk, A.C. (2008). Strong percepts of motion through depth without strong percepts of position in depth. Journal of Vision, 8(6):4, 1-10. [PDF] [online]

Huk, A.C., Dougherty, R.F., & Heeger, D.J. (2002). Retinotopy and functional subdivision of human areas MT and MST. Journal of Neuroscience, 22, 7195-7205. [PDF]

Huk, A.C., & Heeger, D.J. (2002). Pattern-motion responses in human visual cortex. Nature Neuroscience, 5, 72-75. [PDF]

Huk, A.C., Ress, D., & Heeger, D.J. (2001). Neuronal basis of the motion aftereffect reconsidered. Neuron, 32, 161-172. [PDF]

Assorted demos and software site: visualstimul.us.

Working Memory and Decision Making in a Motion Perception Task

Sensory signals are fleeting, but our experiences, decisions, and memories are often dissociated in time from events in the world. We are performing experiments that allow us to test how several parts of the brain accumulate and remember visual motion evidence, building build off a core direction-discrimination task that has been used extensively.

Relevant papers on perceptual decision-making:

Wong, K-F., & Huk, A.C. (2008). Temporal dynamics underlying perceptual decision-making: Insights from the interplay between an attractor model and parietal neurophysiology. Frontiers in Neuroscience, 2(2), 245-254. [PDF]

Wong, K-F., Huk, A.C., Shadlen, M.N., & Wang, X-J. (2007). Neural circuit dynamics underlying accumulation of time-varying evidence during perceptual decision-making. Frontiers in Computational Neuroscience, 1:6. [PDF]

Huk, A.C. & Shadlen, M.N. (2005). Neural activity in parietal cortex reflects temporal integration of visual motion signals during perceptual decision making. Journal of Neuroscience, 25, 10420-10436. [PDF]

Palmer, J., Huk, A.C., & Shadlen, M.N. (2005). The effect of stimulus strength on the speed and accuracy of a perceptual decision. Journal of Vision, 5, 376-404. [PDF]

Motion Signals Underlying Visual Imagery of Motion and Implied Motion

In addition to direct viewing of real motion, we can "perceive" motion by simply imagining it, or by inferring it from a still image. Although we know a lot about how the visual system encodes real motion, the neural computations underlying imagery and inference are less well understood. We are characterizing visual imagery of motion and the processing of implied motion by testing how these processes can produce motion aftereffects, and how they affect activity in motion-responsive parts of the brain.

Winawer, J., Huk, A.C., & Boroditsky, L. (in press). A motion aftereffect from visual imagery of motion. Cognition. [PDF]

Winawer, J., Huk, A.C., & Boroditsky, L. (2008). A motion aftereffect from still photographs depicting motion. Psychological Science, 19, 276-283. [PDF]