Yi Wang

Biography

2000: PhD, University of Osaka, Japan; 2000-2004: Post-doctor, University of Texas-Houston Medical School, USA; 2004-Present: Principal Investigator, Institute of Biophysics, Chinese Academy of Sciences, China. 2000: PhD, University of Osaka, Japan; 2000-2004: Post-doctor, University of Texas-Houston Medical School, USA; 2004-Present: Principal Investigator, Institute of Biophysics, Chinese Academy of Sciences, China.

Research Interest

The research in this laboratory is directed to understand the neural mechanisms underlying visual perception and recognition for objects. We are particularly interested in investigating the cortical representation of object features. The ongoing projects are on the neural coding for luminance, contrast, form, and motion, and also on the functional organization in the visual cortex. In the most situations of the natural vision, the contrast and luminance of images received by neurons in the brain are rapidly varying. How does the brain encode the transient changes in the contrast and luminance remains unclear. By presenting rapidly-varying contrast and luminance stimuli that simulated the transient changes, we explored the response properties of neurons in the primary visual cortex. In the time course of the responses, a neuron increased its activity relative to the mean excitatory level as the stimulus contrast was larger than the averaged contrast in the set of contrasts, whereas decreased its activity as the contrast was smaller than the averaged contrast, that is, the positive signal relative to the mean activity level in the neuronal responses corresponded to the increment intensity in stimulus contrast and the negative one corresponded to the decrement intensity. Generally neuronal response went up to the peak or down to the valley at 30 to 60 ms after stimulus onset. The relative rising or falling magnitudes of the responses at the peak or valley were proportionally correlated to the change magnitudes of stimulus contrast increment or decrement relative to the averaged contrast. The cortical neurons thus represent both the signs and magnitudes of the transient contrast changes relative to the prevailing contrast in the current visual environment by activity- dependent mechanisms. We also compared the responses of neurons to the transient luminance changes with those to contrast changes, suggesting that the mechanisms to process the contrast and luminance are independent. These results show insight into the underlying neural processes responsible for the ability to detect and discriminate contrast and luminance that define the perceptual objects in the natural vision.