Cortical correlates of human motion perception biases
Human sensory perception is not a faithful reproduction of the sensory environment. For example, at low contrast, objects appear to move slower and flicker faster than veridical. While these biases have been robustly observed, their neural underpinning are unknown, thus suggesting a possible disconnect of the well established link between motion perception and cortical responses. We used functional imaging to examine the encoding of speed in the human cortex at the scale of neuronal populations and asked where and how these biases are encoded. Decoding, voxel population and forward- encoding analyses revealed biases towards slow speeds and high temporal frequencies at low contrast in the earliest visual cortical regions, matching perception. These findings thus offer a resolution to the disconnect between cortical responses and motion perception in humans. Moreover, biases in speed perception are considered a leading example of Bayesian inference as they can be interpreted as a prior for slow speeds. Our data therefore suggest that perceptual priors of this sort can be encoded by neural populations in the same early cortical areas that provide sensory evidence
Vintch, B. and Gardner, J. L. (2014) Cortical correlates of human motion perception biases. The Journal of Neuroscience 34: 2592–2604. DOI pdf